Cyclical Ketogenic Diets Review

The 3-Week Ketogenic Diet

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The 3Week Ketogenic Diet Summary

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Polysaccharides are storage and transport forms of carbohydrates produced by photosynthesis

In higher plants, photosynthesis in the leaves provides substrates, such as carbohydrates, for the various heterotrophic plant tissues (e.g., the roots). Substrates delivered from the leaves are oxidized in the root cells by the large number of mitochondria present. The ATP thus generated is required for driving the ion pumps of the roots by which mineral nutrients are taken up from the surrounding soil. Therefore respiratory metabolism of the roots, supported by photosynthesis of the leaves, is essential for plants. The plant dies when the roots are not sufficiently aerated since not enough oxygen is available for their respiration. The various plant parts are supplied with carbohydrates via the sieve tubes (Chapter 13). A major transport form is the disaccharide sucrose, but in some plants also tri- and tetrasaccharides or sugar alcohols. Since the synthesis of carbohydrates by photosynthesis occurs only during the day, these carbohydrates have to be stored in the leaves to ensure...

The glycolysis pathway plays a central role in the utilization of carbohydrates

The carbohydrates delivered by phloem transport to the sink cells are fuel for the energy metabolism and also a carbon source for the synthesis of the cell matter. The glycolysis pathway, which is present at least in part in almost all living organisms, has a fundamental role in the utilization of carbohydrates. The enzymes of this pathway not only occur in sink tissues but are also present in all plant cells. Each cell has two sets of glycolytic enzymes, one in the cytosol and one in the plastids. Some of the plastidic enzymes participate in the Calvin cycle, as discussed in Chapter 6. In the plastids of some plants, the glycolysis pathway is incomplete because one or two enzymes are lacking. The corresponding glycolytic enzymes in the cytosol and in the plastids are isoenzymes encoded by different genes.

Storage and reserve carbohydrates

In addition to carbon allocation into structural components some of the photosynthate is also allocated to a pool of mobile non-structural carbon compounds. This pool represents either storage or reserves and is composed of several compound classes (Chapin et al. 1990 Gower et al 1995). In trees within the timberline ecotone of the central European Alps, the two most important mobile carbon compounds are non-structural carbohydrates (starch, low molecular weight sugars) and lipids (acylglycerols) (cf. Hoch and K rner 2003 Hoch et al. 2003). Depending on the source-sink balance (net canopy photosynthesis versus carbon use for maintenance and growth) non-structural carbon compounds may either accumulate or decrease. Potential periods of carbon shortage in trees at the alpine timberline are the period of winter dormancy and the period of bud break and shoot elongation in spring when carbon demand exceeds carbon supply by photosynthesis (see Fig. 6.16). The largest fraction within the...

Carbohydrates In Leaves

Starch and sucrose are the dominating non-structural carbohydrates in tree leaves and generally function as storage and transport metabolites. Other soluble sugars like hexoses (glucose and fructose), members of the raffinose family (raffinose, stachyose), as well as sugar alcohols are synthesised to considerable amounts under certain metabolic situations and are involved in carbon transport, cell elongation and cryoprotection (1-3). As end-products of photosynthesis starch and sucrose can be converted into each other. Pool sizes of both carbohydrates are determined by their relative rates of synthesis and degradation as well as transport activities (import and export). After the initiation of frost adaptation, all levels of soluble sugars (sucrose, glucose, fructose, raffinose and stachyose) decreased, while starch contents increased dramatically during a period of a few weeks reaching up to 13 of the dry matter (8, 15). Inspite of the accumulation of carbohydrates in one-year-old...

Carbohydrates In Wood

In all living perennial organs of a woody plant carbohydrates serve different purposes such as organic osmolyte, carbon transport, and most importantly, for carbon storage. In angiosperm and gymnosperm trees, bark and living wood parts of the trunk are the dominating storage compartments. These storage tissues are filled during favourable periods and cleared at times of demand such as leaf growth, formation of new roots and twigs, and cambial growth of trunks and roots in early spring and during summer. According to the predominant carbon storage compounds, starch or fat, trees are classified, as starch trees like most ring-porous angiosperms and some conifers like species of Abies and Picea or fat trees like most diffuse-porous angiosperms and species of Pinus (61-62). In the following, storage carbohydrates of trunk tissues, their nature, localization within the organs as well as their synthesis and cleavage will be summarized. The radial and seasonal distribution will be discussed...

Carbohydrates In Roots

The roots of most trees are invaded by mycorrhizal fungi. These interact specifically with the fine root system (less than 1 mm diameter) and, due to their high carbon demand, affect the carbon status of the whole root system. Carbon metabolism of roots of trees has thus to be seen as the consequence of organismic interaction in which bacteria of the rhizosphere are also involved. With regard to mycorrhiza, the most common of these symbiotic associations in trees of temperate forests are ectotrophic. Tropical trees and many terrestrial flowering plants develop vesicular-arbuscular (VA) mycorrhizas. Estimates are that up to 90 of angiosperms establish this kind of symbiosis (91). The development of these symbiotic structures is a complex process which depends on a variety of internal and external factors of which mineral nutrition and the supply of carbohydrates by the host plant are most important (for a recent overview on types of mycorrhiza and function see reference 92). 4.2....

Production of Novel Carbohydrates in Transgenic Plants

In addition to attempts aiming at manipulating the contents and properties of endogenous carbohydrates, there have been several successful approaches for the production of novel carbohydrates in transgenic plants. By expressing enzymes that act on sucrose or sucrose biosynthetic intermediates, novel compounds can theoretically accumulate to high levels. Fructans, or polyfructosylsucroses, are alternative storage carbohydrates that are highly soluble and are stored within the vacuole as opposed to the plastid they are present in approximately 15 of all flowering plants (Hellwege et al., 2000). Fructan synthesis is initiated by sucrose sucrose 1-fructosyltransferase (SST) which catalyses the fructosyltransfer from one sucrose molecule to another, resulting in the trisaccharide 1-kestose. In subsequent steps fructosyltransferase (FFT) catalyses the reversible transfer of fructosyl residues from one fructan to another, producing a mixture of fructans with different chain lengths (Ritsema...

Carbohydrates And Related Compounds

Carbohydrates are the most abundant class of organic compounds found in living organisms. They originate as products of photosynthesis, an endothermic reductive condensation of carbon dioxide requiring light energy and the pigment chlorophyll. Carbohydrates are a major source of metabolic energy, both for plants and for animals that depend on plants for food. Apart from the simple sugars, they provide a means of storing energy (starch) that meets this vital nutritional role and transport of energy (as sucrose). Carbohydrates also serve as a structural material (hemicellulose, cellulose), as a component of the energy transport compound ATP, recognition sites on cell surfaces, one of three essential components of DNA and RNA and plant glycosides. They also play a number of ecological roles, in plant-animal interactions (flower nectar is mainly sugars), in protection from wounds and infections, and in the detoxification of foreign substances. The major simple sugars present in plants are...

Carbohydrates

Carbohydrates are a diverse group of compounds composed of the elements carbon (C), hydrogen (H), and oxygen (O) with the empirical formula CH2O n, where n represents the number of CH2O units in the compound. The ultimate source of all carbohydrates is photosynthesis, in which the energy of sunlight is used to chemically fix atmospheric CO2 into carbohydrate. Carbohydrates constitute as much as 80 percent of the dry weight of a plant. This is largely due to the presence of cell walls made of complex carbohydrates surrounding each plant cell. Sugars, also called saccharides, are carbohydrates. Common sugars occurring in nature have from three (glyceraldehyde) to seven (sedoheptu- Carbohydrates are important in human nutrition, often constituting the major source of calories in the diet. Glucose, fructose, sucrose, and starch are readily digested by humans. Cellulose and the other complex carbohydrates of the plant cell wall are not readily digested, but constitute useful dietary fiber.

Vacuoles have multiple functions

Vacuoles have an important function in recycling those cellular constituents that are defective or no longer required. Vacuoles contain hydrolytic enzymes for degrading various macromolecules such as proteins, nucleic acids, and many polysaccharides. Structures, such as mitochondria, can be transferred by endocytosis to the vacuole and are digested there. For this reason one speaks of lytic vacuoles. The resulting degradation products, such as amino acids and carbohydrates, are made available to the cell. This is especially important during senescence (see section 19.5) when prior to abscission, part of the constituents of the leaves are mobilized to support the propagation and growth of seeds. In addition, vacuoles also have a storage function. Many plants use the vacuole to store reserves of nitrate and phosphate. Some plants store malic acid temporarily in the vacuoles in a diurnal cycle (see section 8.5). Vacuoles of storage tissues contain carbohydrates (section 13.3) and storage...

Peroxisomes are the site of reactions in which toxic intermediates are formed

Peroxisomes, also termed microbodies, are small, spherical organelles with a diameter of 0.5 to 1.5 im (Fig. 1.14), which, in contrast to plastids and mitochondria, are enclosed by only a single membrane. The peroxisomal matrix represents a specialized compartment for reactions in which toxic intermediates are formed. Thus peroxisomes contain enzymes catalyzing the oxidation of substances accompanied by the formation of H2O2, and also contain catalase, which immediately degrades H2O2 (section 7.4). Peroxisomes are a common constituent of eukaryotic cells. In plants perox-isomes occur in two important differentiated organelle types the leaf per-oxisomes (Fig. 1.14A), which participate in photorespiration (Chapter 7) and the glyoxysomes (Fig. 1.14B), which are present in seeds containing oils (triacylglycerols) and play a role in the conversion of triacylglycerols to carbohydrates (section 15.6). They contain all the enzymes for fatty acid P-oxidation. Peroxisomes multiply by division,...

Mycorrhiza and growth of the host

Increases of the rate of growth of mycorrhizal plants measured in these ways are usually observable when the potential for active photosynthesis is high (e.g. adequate light) and when there is a deficit or rather no excess of one or more essential nutrient such as phosphate or nitrogen source. Where increases are not observable they are often associated with very ready availability of nutrients or a low light supply. In addition, there are variations in the efficiency of the fungi which can form mycorrhiza, and a strain may be ineffective or inefficient in some environmental conditions. In some cases there may be little effect of mycorrhizal formation, or perhaps an actual decrease in growth rate of the host may be observed. In some cases, where growth experiments have been performed on a range of phosphate concentration in soil, a depression of growth in mycorrhizal plants may occur at a high nutrient level. The causes of this are discussed by Harley and Smith, S. E. (1983) with many...

Sugars and Sugar Alcohols

Several studies have been attempted to relate the magnitude of changes in soluble carbohydrates to salinity tolerance. Parida and Das (2005) found out that carbohydrates such as sugars (glucose, fructose, sucrose, and fructans) and starch are accumulated under salt stress. Furthermore, Megdiche et al. (2007) and Geissler et al. (2009a) proved that Cakile maritima and Aster tripolium plants accumulate high amounts of total soluble carbohydrates and Pro at high salinity (400 and 500 mM NaCl, respectively). The major functions of sugars and sugar alcohols are osmoprotection, osmotic adjustment, carbon storage, and radical scavenging (Adams et al. 2005 Ashraf et al. 2006 Messedi et al. 2006 Lee et al. 2008 Ahmad and Sharma 2008). Furthermore, there is a discussion about that they serve as molecular chaper-ones (Hasegawa et al. 2000 Liu et al. 2006).

Problems in Determining Reproductive Allocation

Antonovics, 1980 Jurik, 1983 Jolls, 1984). In these studies, energy content of various plant compartments were then compared at one point in time. However, evidence was accumulating from the 1960s that reproductive structures may have a considerable photosynthesis of their own. This was first investigated for the carbon contribution from ear photosynthesis for grain filling in cereals (Watson et al., 1963 Thorne, 1963, 1965 Carr and Wardlaw, 1965 Evans and Rawson, 1970). Later also other species were found also to show similar patterns (Maun, 1974 Ong et al, 1978, Bazzaz and Carlsson, 1979 Bazzaz et al, 1979). Furthermore, it was found that nectar production can consume significant amounts of carbon (Southwick, 1984), and the presence of reproductive structures may enhance leaf photosyn-thetic capacity (Reekie and Bazzaz, 1987a Laporte and Delph, 1996). However, in some cases, reproduction has no (Houle, 2001) or a reverse effect (Karlsson, 1994 Obeso et al, 1998) on leaf...

The use of energy from sunlight by photosynthesis is the basis of life on earth

Plants and cyanobacteria capture the light of the sun and utilize its energy to synthesize organic compounds from inorganic substances such as CO2, nitrate, and sulfate to synthesize their cellular material they are photoau-totrophic. In photosynthesis photon energy splits water into oxygen and hydrogen, the latter bound as NADPH. This process, termed the light reaction, takes place in the photosynthetic reaction centers embedded in membranes. It involves the transport of electrons, which is coupled to the synthesis of ATP. NADPH and ATP are consumed in a so-called dark reaction to synthesize carbohydrates from CO2 (Fig. 2.1). The photosynthesis of plants and cyanobacteria created the biomass on earth, including the deposits of fossil fuels and atmospheric oxygen. Animals are dependent on the supply of carbohydrates and other organic compounds as food they are heterotrophic. They generate the energy required for their life processes by oxidizing the biomass, which has first been...

Carbon physiology of mycorrhizal symbioses

A graphic experimental demonstration of this behaviour was provided by Lewis and Harley (1965), using excised mycorrhiza. They showed that if 14C sucrose was applied to the cut axis, 14C carbohydrate was translocated to the tip and accumulated particularly in the fungal sheath in the form of the fungal carbohydrates trehalose, mannitol and glycogen, carbohydrates not readily used by the host tissues. These examples emphasize a similar pattern to rust fungi and have indeed been accepted widely as the most likely behaviour in all mycorrhiza. However, caution is necessary, because it does not seem so easily applicable to vesicular-arbuscular mycorrhiza (see Smith, S.E. and Gianinazzi-Pearson, 1988), although lipids, glycogen granules, polyols and trehalose have at times and to some extent been found in their hyphae. It is clear that more investigation is needed, especially into the substances which become labelled in vesicular-arbuscular fungi and into the actual carbonaceous substances...

Carbohydrate Partitioning and Plant Growth

Plants convert sunshine radiant energy into chemical energy by the process of photosynthesis, and the first stable compounds formed are carbohydrates. As sugars, carbohydrates are transported within a plant and used both as building blocks of structure and for energy for respiration to fuel growth. Some sugars are synthesized into cellulose and related compounds that make up the great majority of the structure of plants. Energy is also stored in the form of sugars that can be used quickly by respiration or in polysaccharides such as starch that provide reserve stores of energy. For these reasons, carbohydrates are the most critical and ubiquitous compounds in plants. Carbohydrate partitioning (i.e., distribution) determines amounts and patterns of plant growth and yields of crops. Consequently, much research has been done to document and understand these patterns and regulation of the production and partitioning of carbohydrates in plants.

Seasonal Patterns Of Carbohydrate Production

Before considering the partitioning of carbohydrates, seasonal production of carbohydrates must be understood. Temperate tree fruit are perennial plants with permanent structures that provide physical frameworks of canopies and root systems that do not need to be reproduced each season, as in annuals. Additionally, these structures contain reserves of carbohydrates and mineral nutrients that can immediately be used for early growth. Temperate tree fruit can develop full canopies and intercept sunlight to produce carbohydrates very early in the season compared to annual crops because they have thousands of preformed buds. Indeed, orchards may almost reach full light interception at the time many annual crops are planted. This leads to a rapid increase in total carbohydrate production early in the season. Photosynthesis produces carbohydrates for growth and energy. The energy needed to drive growth and maintenance of a tree is generated by using carbohydrates. The percentage of fixed...

Recognition between the symbionts

The very fact that in the soil a root is surrounded by many species of fungi and only certain of these form composite mycorrhizal organs with it, demonstrates that there must be some method of recognition between potential symbionts. This method of recognition cannot solely involve the production of common substances like simple carbohydrates, an earlier suggestion for this process, for such common substances can be utilized by many soil organisms.

The mechanisms regulating NO3 uptake

Experimentally, NO3- uptake can be increased in parallel with the growth rate by increasing light intensity (e.g. Gastal and Saugier 1989). The diurnal regulation of NO3- uptake (higher rate during the light period, lower rate during the dark period) has been considered as a specific example of its regulation by light (Delhon et al. 1995). The stimulation of NO3- uptake by light is attributed to photosynthesis, since it could be prevented by decreasing the atmospheric CO2 concentration (Delhon et al. 1996). Moreover, the addition of carbohydrates to the nutrient solution is known to increase NO3- uptake (Hanisch Ten Cate and Breteler 1981). Blocking phloem translocation in soybean plants by means of stem girdling led to a decline in the rate of NO3- uptake, which is partially restored by adding glucose to the nutrient solution (Delhon et al. 1996). No consensus exists that an energetic shortage might occur in roots, even at night, and an increased energisation of the plasma membrane...

Partitioning To Tree Organs

To grow and produce a crop, all the critical organs of a fruit tree must receive carbohydrates for growth and maintenance. A unique feature inherent to perennial crops is that flower buds for the next year's crop are developing on a tree during the growth of the current year's crop. So although growers and consumers are interested in the fruit component, the perennial nature requires that vegetative organs (shoots, roots, and structure) and developing flower buds receive an adequate share of carbohydrates to sustain cropping in following years. There have been many studies of the actual partitioning of dry matter (not precisely carbohydrates, but a close approximation) in temperate tree fruit. The individual organs on a fruit tree have genetically programmed growth patterns and carbohydrate requirements. However, it appears that overall partitioning of carbohydrates within a tree is not a genetically programmed process, but a result of the unique combination of competing organs and...

Similar Secondary Metabolism of the Large Solanales Families

Of course, classes groups of metabolites which occur (almost) ubiquitously or at least frequently in the plant kingdom (general secondary metabolites) are also constituents of both large Solanales families (i) phenolics such as simple cinnamic acid derivatives (Sect. 6.4), hydroxycoumarins (Sect. 6.6), hydroxycinnamate conjugates (Sect. 6.7), flavonoids (Sect. 6.8), lignans (Sect. 6.9), (ii) sterols (Sect. 7.6), (iii) carotenoids (Sect. 7.12), (iv) fats oils and fatty acids (Sect. 8.1), (v) carbohydrates (Sect. 8.2) etc.

Conclusion and Future Perspective

Experience drought and 19.5 of the irrigated land are affected by salinity. These problems will be further catalyzed by global climate change. Prolonged environmental stresses are responsible for the production of ROS in different cell compartments like chloroplasts, mitochondria, per-oxisomes, etc. ROS attack biomolecules, viz., DNA, lipids, proteins, carbohydrates, and disturb the normal functioning of the cell. Under severe stress conditions, ROS ultimately lead to cell death. In order to withstand oxidative stress, plants are equipped with enzymatic and nonenzy-matic antioxidants. Many workers have reported the positive effects of SOD, CAT, APX, GR, MDHAR, AsA, glutathione, etc., in combating oxidative damage to the cell. To overcome the deleterious effects of abiotic stresses, plants also accumulate osmolytes and osmoprotectants such as proline and glycine betaine. These compounds are thought to play a role in osmotic adjustment and protect subcellular structures. Elevated...

Genetic Control of Growth

Clair, 1994a,b). The variability in biomass partitioning and wood density indicated that genetic gains may be expected from selection and breeding of desirable genotypes. Some of the crown structure traits showed promise as potential ideotype traits. Large trees that grew vigorously in their growing space had tall, narrow crowns, large leaf areas, and preferential partitioning of carbohydrates to leaves over branches.

Environmental Factors Affecting Partitioning Light Availability

With fruiting trees, the effects can be complex. If fruit set has already occurred, low light reduces fruit growth and especially vegetative growth, as the fruit compete strongly for carbohydrates. If, however, low light occurs early in the season before fruit are set, growing shoots tend to be stronger competitors and fruit set may be reduced, even leading to complete defruiting. Then, partitioning develops as just described for nonfruiting trees.

Malespecific Health Considerations

No single nutrient is more important than zinc for maintaining a man's overall reproductive and sexual functioning. In fact, the prostate is the richest reservoir of zinc within the body. Zinc helps to ensure overall virility, including erectile function and sperm quality.6,7 Diet also can play a critical role in prostate health. Eating a diet high in protein can inhibit the enzyme, 5-alpha reductase. This enzyme converts testosterone into the more potent hormone dihy-drotestosterone (DHT), which when levels are elevated, causes the increased growth of the prostate, leading to pelvic congestion and an obstructed flow of urine. In contrast, a diet that is high in carbohydrates can actually contribute to a buildup of DHT. Recommendations for maintaining a healthy prostate call for a dietary balance of protein, 44 complex carbohydrates, 35 and mostly unsaturated fats, 21 .8

Carnivorous PlantsAn Introduction

Green plants can derive a large part of their chemical requirements for sustaining growth and reproduction from some very basic but essential elements. These include energy from sunlight, oxygen and carbon dioxide from the air, and water and certain minerals from the earth or water in which the plants grow. Through photosynthesis, in which green chlorophyl plays so large a part by transforming sunlight into chemical energy, carbohydrates are built up from water and carbon dioxide. These various carbohydrates themselves are used as energy sources and building blocks for synthesizing myriad other chemical materials needed by the plant products such as amino acids and proteins, vitamins and hormones, and even small quantities of fats.

The photosynthetic machinery is constructed from modules

Purple bacteria have only one reaction center (Fig. 3.1). In this reaction center the energy of the absorbed photon excites an electron, which will be elevated to a negative redox state. The excited electron is transferred back to the ground state by an electron transport chain, called the cyto-chrome- ci complex, and the released energy is transformed to a chemical compound (NADH), which is then used for the synthesis of biomass (e.g., proteins and carbohydrates). Generation of energy is based on coupling the electron transport with the transport of protons across the membrane. In this way the energy of the excited electron is conserved as an electrochemical H+-potential across the membrane. The photosynthetic reaction centers and the main components of the electron transport chain are always located in a membrane. Via ATP-synthase the energy of the H+ -potential is used to synthesize ATP from ADP and phosphate. Since the excited electrons in purple bacteria return to the ground...

Concepts And Definitions

Ideally, photoautotrophic micropropagation should be segregated from sugar-free micropropagation. However, in this chapter, while we will define photoautotrophy as the plant nutritional type where only endogenous carbohydrate is used as the energy source, for all practical purposes photoautotrophic micropropagation refers to micropropagation with no sugar added to the medium. Sugars and other carbohydrates may be significant components of agar and other gelling agents, but perhaps it is reasonable not to consider it as an exogenous carbohydrate source in the practical definition of photoautotrophic micropropagation.

Out By Fungi 141 Making Nutrients Available

As with other micro-organisms, fungi obtain their energy and nutrients by the secretion of extracellular enzymes into the environment. Degradation products, containing carbohydrates and or mineral nutrients, are then absorbed by the hyphae and distributed within the organism by translocation. This process is termed saprotrophy and has important consequences outside the mere nutrition of the fungus. The process of extracellular degradation of resources is less efficient than ingestion of food into a gut, resulting in a fraction of the useful resources being released into the environment around the fungus. This inefficiency results in one of the key functions of saprotrophic soil fungi, the mineralization of nutrients into the soil nutrient pool (Dighton, 1997). This attribute will be discussed in more detail as it pertains to the supply of nutrients for primary productivity. In addition to the usage of organic components of the soil, leaf litter, woody debris, and animal remains, there...

Life histories reproductive strategies and allocation

It has been suggested that, to some extent, plants can escape the seed size--number trade-off by modifying the chemical composition of their seeds (Lokesha et al., 1992). There is some evidence that light wind-dispersed seeds are better dispersed than heavier seeds of similar morphology (e.g. Meyer & Carlson, 2001), although this may not apply to all dispersal modes (Hughes et al., 1994a). Since fats yield about twice the energy of carbohydrates per unit mass, a plant could make seeds half as heavy by replacing stored carbohydrate with fats. In fact, the majority of plant species mostly store fats in their seeds, although there are costs lipid synthesis is more energetically demanding than either protein or carbohydrate production. If lighter seeds are dispersed more effectively by wind, then we might expect fat storage to be more prevalent in

Results and Discussion

Feeding myo-inositol up to 50 mM increased free myo-inositol slightly (d-pinitol and d-chiro-inositol even less) with a doubling of galactinol after feeding 25-50 mM myo-inositol, but had little effect on other soluble carbohydrates (Fig. 6.1A-C). Elevated myo-inositol concentrations decreased as galactinol increased transiently during days 2 and 3 and then galactinol decreased as raffinose and stachyose accumulated (Fig. 6.1D-F). Total myo-inositol decreased, indicating metabolism to other products (phytic acid, cell wall pectins). After feeding sucrose with myo-inositol, sucrose concentration decreased and raffinose and stachyose concentrations increased during slow drying (Fig. 6.1F). Fig. 6.1. (A-C) Accumulated soluble carbohydrates in cotyledon tissues after precocious maturation of immature soybean embryos as a function of m o-inositol concentration after feeding m o-inositol (0-100 mM) plus sucrose (100-0 mM) (100 mM total concentration) for 24 h at 25 C followed by 14 days...

Fungal Effects on Populations and Communities

Fungi may be selective in their source of a food base or may be restricted in terms of resource exploitation by competition with other fungal species. Providing the resource contains carbohydrates for energy and nutrients for growth, however, this resource can come from living or dead plant or animal tissue or merely from chemicals in the atmosphere (Wainwright et al., 1997). This leads to another property of fungi, their pathogenicity to both plants and animals, whereby the fungi eat living organisms. The role of fungal pathogens in agriculture has been

Physiological Basis For Dormancy

Just as the forms of dormancy are complex and diverse, the explanations for dormancy are varied. Simple models attribute ecodormancy to balances of water, carbohydrates, and energy within the growing meristem. As environmental conditions become less favorable, metabolic functions slow or change. For instance, as temperatures go below or above those that are optimal for metabolism, the reactions slow and

Endocytic Internalization of Cell Wall Molecules

JIM5-reactive pectins accumulate in BFA compartments and within cell plates together with boron and calcium crossed-linked RGII pectins (Baluska et al. 2002, 2005 Samaj et al. 2004). In addition, they were reported to localize also to plasma membrane invaginations and adjacent multivesicular bodies in stylar transmitting tissue of Datura (Hudak et al. 1993). In contrast, Golgi-derived JIM7-reactive pectins did not show this endocytic localization. Hudak et al. (1993) showed that plasma membrane invaginations as well as multivesicular bodies contain carbohydrates and are filled with fib-rillar material resembling cell wall components. Similar fibrillar material of cell wall origin, identified as arabinogalactan-type pectins, was reported in multilamellar compartments invaginating into vacuoles of bean root cells and accumulating within cell plates (Northcote et al. 1989). Besides cross-linked cell wall pectins, arabinogalactan proteins (AGPs) were also reported to be

Trace Element Solubility In The Rhizosphere

Although the exact composition of dissolved organic matter is variable and complex, a large portion of this mobile material is composed of fulvic and humic acids. Minor components can also include macromolecular hydrophilic acids, carbohydrates, and carboxylic and amino acids 4 . Dissolved organic matter has been demonstrated to promote heavy-metal solubility 5 and mobility,

Mitochondria are the power station of the cell

In the process of biological oxidation, substrates such as carbohydrates are oxidized to form water and CO2. Biological oxidation can be seen as a reversal of the photosynthesis process. It evolved only after oxygen accumulated in the atmosphere during photosynthesis. Both biological oxidation and photosynthesis serve the purpose of generating energy in the form of ATP. Biological oxidation involves a transport of electrons through a mitochondrial electron transport chain, which is in part similar to the pho-tosynthetic electron transport discussed in Chapter 3. The present chapter will show that the machinery of mitochondrial electron transport is also assembled of three modules. The second complex has the same basic structure as the cytochrome- complex of the chloroplasts. As in photosynthesis, the mitochondrial oxidative electron transport and ATP synthesis are coupled to each other via a proton gradient. The synthesis of ATP proceeds by an F-ATP synthase, which was described in...

Metabolites and Enzymes for Chemical Defense

Plant chemicals that play a role in direct defense impair herbivore performance by one of two general mechanisms these chemicals may reduce the nutritional value of plant food, or they may act as feeding deterrents or toxins. There has been considerable debate as to which of these two strategies is more important for host plant selection and insect resistance. An important part of this debate concerns the extent to which variation in the levels of primary and secondary metabolites has evolved as a plant defense (Berenbaum, 1995). Plant primary metabolism, which is shared with insects and other living organisms, provides carbohydrates, amino acids, and lipids as essential nutrients for the insect. Food quality is largely determined by the availability of these nutrients, and its importance for longevity, size, fecundity, and death rates in herbivorous insects has been recognized early on by Painter (1936). In addition, more than 100,000 plant compounds (i.e., secondary metabolites)...

Dietary Interventions

Dietary whole grains have also been associated with decreased cardiovascular risk. Whole-grain foods provide complex carbohydrates, dietary fiber, minerals, vitamins, and antioxidants. Research indicated that whole grain dietary intake decreases the risk of hypertension, myocardial infarction, and heart failure.87 In one study to evaluate the role of whole grains and atherosclerosis, whole-grain intake was evaluated and carotid intimal medial thickness was measured. Whole-grain intake was shown to be inversely associated with common carotid artery intimal medial thickness and intimal medial thickness progression.88 A 12-week, randomized, controlled trial compared two whole-grain oat-based cereals with two refined grain wheat-based cereals to evaluate their effects on the need for antihypertensive medications in patients with hypertension. At the end of 12 weeks, 73 of participants in the oats group versus

Overview of Aleurone Ontogeny

The final stage in the life of an aleurone cell occurs after seed imbibition when the embryo sends a GA signal that induces the germination function of the aleurone. Hydrolase genes such as a-amylase are induced and their products secreted into the starchy endosperm for the remobilization of stored carbohydrates and amino acids to supply the growing seedling. This is a terminal process in that the aleurone cells expend all their resources and undergo non-apoptotic programmed cell death (Bethke et al. 1999 chapter by Nguyen et al., in this volume).

Conclusions And Future Lines Of Research

Iron deficiency in trees develops progressively over the years unless some kind of Fe fertilization is used. This deficiency is assumed to deplete progressively the pools of Fe, carbohydrates and other nutrients in the tree. There are no studies, however, on the effects of the chlorosis evolution over

Nitrogen Use Efficiency Nue Interactions between photosynthesis and nitrogen

Since the eighties of the last century it is well known that growth conditions leading to higher levels of endogenous NH4+and or relatively low levels of carbohydrates result in relatively high levels of GDH. At that time the regulation of nitrate reductase appeared to be fairly straight forward, but regulation of NH4+ assimilation appeared to be complex (Oaks 1986). That photosynthesis supplies

Genetic manipulation for the improvement of NUE

Amenziane et al. (2000) introduced the gdhA gene from Escherichia coli encoding a NADPH-GDH into tobacco plants and expressed under the control of 35S promoter. The introduced NADPH-GDH was apparently able to assimilate some of the excess NH4+, resulting from the increase in free amino acids, carbohydrates, and biomass production in the transgenic plants grown under controlled conditions or in the field. Transgenic wheat plants expressing the a-isoform of the Chlorella NADPH-GDH gene (aminating GDH) showed an increase in grain yield (Schmidt R., personal communication). Since the gene product contains a chloroplast-targeting transit peptide, the translated a-isoform GDH is localised in chloroplasts in the transgenic wheat. It has been shown that NH3 emission from barley leaves (Mattsson and Schjoerring 1996) and oil seed rape (Mattsson et al. 1997) occurs in plants grown hydroponically with 2 mM NH+ in the light, but not with NO3-. An inhibitor of GS increased the emission, while an...

Heterogeneity of Light Use Across the Leaf Lamina

In full grown leaves, Fv Fm was higher in intercostal tissue than in vein tissue. This indicates that in early phases of post-emergent leaf development, an increased amount of photosynthates might be required for energy-consuming growth processes within the leaf vein tissue, while differentiation of the pho-tosynthetic machinery can proceed more slowly in intercostal tissue. There, carbohydrates can be supplied in sufficient amount via phloem import.

The Carbohydrate Metabolism Mediates Between the Gain of Light Energy and the Production of Biomass

A close investigation of the connection between carbohydrate metabolism and growth dynamics is necessary to move towards a mechanistic understanding of the spatial and temporal relations between energy gain in photosynthesis and biomass production during growth processes. Carbohydrates are the transportable currency unit that is produced in photosynthesis. The majority of plant dry matter consists of carbohydrates, mainly cellulose, hemicellulose and starch. Carbohydrate metabolism is governed by diel or circadian rhythms and concentrations of carbohydrates in leaves typically reach maxima at day (Kemp and Blacklow 1980 Matt et al. 1998 Geiger et al. 2000 Chia et al. 2004 Walter and Schurr 2005). The circadian clock not only governs carbohydrate metabolism but a large number of metabolic, physiological or ontogenetic processes in plants (Somers 1999 McClung 2001 Staiger 2002 Schultz and Kay 2003 Luttge 2003). The performance of a plant is clearly increased by optimized temporal...

Variation of Diel Leaf Growth Cycles

For extreme situations it has been shown that alterations of the diel variation of carbohydrate metabolism can induce changes of the diel leaf growth pattern. In leaves of Populus deltoides that were exposed to a three-times elevated CO2-content, a strong, transient decay of growth rate was observed during the afternoon, which temporally coincided with a transient decrease of glucose content (Walter et al. 2005). An amplification of nocturnal growth activity was found in leaves of transgenic potato plants that showed an increased starch content at the end of the day (Kehr et al. 1998), indicating that the pool of transitory starch is of utmost relevance for nocturnal growth activity. A clear indication how carbohydrate metabolism affects diel leaf growth cycles was recently observed in Arabidopsis thaliana Starch-free-mutant plants (stfl, Kofler et al. 2000) that do not possess a relevant pool of transitory starch showed much lower growth rates than wild-type plants at night, but were...

Formation of Humic Substances and Organomineral Complexes

Humic substances are formed through biotic and abiotic processes (Stevenson, 1994 Huang, 2004). A variety of biomolecules, such as carbohydrates, phenolic compounds, and amino acids, can participate as raw materials. Soil mineral surface chemistry plays a vital role in the catalysis of abiotic formation of humic substances. The Maillard reaction (Maillard, 1913) is perceived to be a major pathway in humification because of significant similarities between humic substances and melanoidins formed through this pathway involving sugar-amino acid condensations (Ikan et al., 1996). The presence of characteristic products of the Maillard reaction (alkyl pyrazines) was detected in archaeological plant remains up to 1500 years in age (Evershed et al., 1997). The great appeal of the Maillard reaction in humification processes lies in the two types of precursors, sugars and amino acids, which are among the most abundant constituents of

Small Scale Variation of Leaf Growth

Carbohydrate production of the growing leaf itself might affect the homogeneity of growth distribution within the lamina (Walter et al. 2005) When comparing leaves of Populus deltoides that were exposed to the sun with leaves that were completely shaded, but growing on sunlit trees, it was observed that relative growth rate distribution across the lamina was more patchy and temporal fluctuation of average relative leaf growth rate was much stronger in leaves that grew in the shade. At night, leaves of both populations showed comparable temporal fluctuations of relative growth rate. This leads to the speculation that in shaded leaves the fluctuating but strong import of carbohydrates from source leaves led to spatial and temporal heterogeneities of growth that were dampened in the case of sunlit growing leaves by the stabilizing effect of carbohydrates produced on-site.

Nutritional Strategies for Prevention

The fiber from wheat bran, for example, is deserving of special attention, as it may be able to decrease the risk of colon cancer via various mechanisms. One of the principal ways in which a high cereal fiber diet may be beneficial is by decreasing the amounts of secondary bile acids that are irritating to the colonic mucosa. In fact, at least one of these secondary bile acids, deoxycholic acid, increases the proliferation of colonic epithelial cells.12 Research has shown that these bile acids, including deoxycholic acid, were significantly reduced when subjects consumed 10 g per day of wheat bran, but not oat bran, as an addition to their typical Western diet.13 Also, intake of dietary carbohydrates, particularly from degradation-resistant starches and dietary fiber, are fermented in the colon and form short chain fatty acids (SCFA), primarily acetate, propionate, and butyrate. These SCFAs have been shown to decrease proliferation and migration in experimentally induced cancer cell...

The Mode Of Action Of Allelochemicals

Shikimate pathways, by natural elicitors such as fish protein hydrolysates (FPH), lactoferrin (LF) and oregano extract (OE). Elicitation significantly improved the phenolic, antioxidant and antimicrobial properties of mung bean sprouts. The optimal elicitor concentrations were 1 ml l FPH, 250 ppm LF and 1 ml l OE for the highest phenolic content that was approximately 20, 35 and 18 higher than control, respectively, on day 1 of dark germination. The antioxidant activity estimated by P-carotene assay in mung bean sprouts was highest on day 1 of germination for all treatments and control. in general, higher antioxidant activity was observed in the elicited sprouts compared with control. In the case of 1,1-diphenyl-2-picrythydrazyl (DPPH) assay the antioxidant activity for all treatments and control was highest on day 2. Among the different elicitor treatments, OE elicited mung bean sprouts showed the highest antioxidant activity of 49 DPPH inhibition on day 2. This increased activity...

Mode of action studies

Be predicted for herbicides because of the wide variety of organic phases within a plant, such as hydrocarbon waxes, triglycerides, proteins, lignins or even carbohydrates. However, Briggs and colleagues (Bromilow et al., 1986I have found that the partition coefficient can give a good prediction of systemicity. For acids and bases the dissociation constant of the chemical and the natural pH of the various plant compartments will also determine the proportion of ionised and non-ionised forms present. Ionisation decreases log Kow and so can have a dramatic effect on the movement of a compound in a plant. Most phloem-mobile, systemic compounds are therefore weak acids with log Kow in the range of -1 to 3, but the immobile soil-applied herbicide diflufenican has a log Kow value of 4.9 (Table 2.9).

Specialized Staining Techniques

The PAS reaction is useful for looking at cell walls, especially in meris-tematic tissues (Baum and Rost 1996). Total carbohydrates of insoluble polysaccharides (e.g., starch and cellulose) stain magenta to purplish red. Aldehyde-fixed tissue reacts with SchifPs bases to yield a false positive background, but this is not a problem in most situations. If problems are experienced, the reaction can be blocked (see Ruzin 1999).

13CNMR studies of carbon metabolism

Carbon-14 has been used to enable measurements of flux through metabolic pathways for decades. Significant information is provided by purification and chemical degradation of metabolic intermediates and measurement of the specific activity of each carbon of a metabolite. Due to a practical limit on the number of measurements that can be made, the metabolic analysis provided by most 14C investigations is limited. NMR offers several advantages for metabolic studies, including identification and quantitation of multiple metabolites (e.g. amino acids, carbohydrates, organic acids, etc.) from a single spectrum (Fig. 4). Carbon-13 has a natural abundance of only 1.1 therefore most 13C-NMR studies require the preparation to be enriched with 13C, or are restriced to investigations of highly concentrated metabolites such as fatty acids, glycogen and storage carbohydrates (Fig. 4). For many experiments this is an advantage, as specifically labelled compounds can be added to cell preparations...

General Anatomical Characteristics Of In Vitro Plants

Most of the researches pointed out that under these conditions the anatomical features of the plants are at least to some extend different (abnormal) than the normal in vivo plants, they have a significantly higher content of carbohydrates, mostly in the leaves (Kozai and Zobayed, 2001). Thus the leaves have a poorly developed internal structure and become physiologically abnormal and simply act as a storage organ. It has also been concluded that the poor ventilation or restricted air exchange in the conventional culture vessel can lead to the development of abnormal anatomical features which could prevent or reduce the plant's ability to acclimatize ex vitro (Zobayed et al., 2001a).

Dietary Interventions In Diabetes Mellitus

One form of fiber that may be particularly useful for treating patients once they are diagnosed with either type 1or type 2 diabetes is the fiber from legumes. In one study of 9 patients with type 1 diabetes and 18 with type 2 diabetes, subjects were placed for six weeks on a high carbohydrate diet that was rich in legumes and then also a low-carbohydrate diet for six weeks.63 In subjects with diabetes of either type, the mean preprandial and two-hour postprandial blood glucose levels were significantly lower when the subjects were on the diet that was rich in legumes. The amount of glucose passed in the subjects' urine was also significantly less when they were on the high legume diet.

Carbohydrate biosynthesis

Mannitol is the main soluble carbon storage compound in several fungi, including those that are ectomycorrhizal (Martin et al., 1987), and it has been suggested that it plays an important role in the carbon transfer between the mycorrhizal symbionts. However, its metabolism is poorly known. A problem that is suitable for NMR analysis is the determination of its pathways of synthesis and degradation. When C. geophilum, Sphaerosporella brunnea and Piloderma croceum were fed with l-13C glucose, this polyol contained the highest proportion of carbon from assimilated glucose (Martin et al., 1985a, 1988) (Fig. 5), indicating that it is an important component of carbohydrate conversion and biosynthesis. More than 70 of the 13C label accumulated in mannitol. Mannitol has been proposed to be metabolized in a cyclic pathway in certain Fungi Imperfecti (Hult and Gatenbeck, 1978) and in ectomycorrhizal fungi (Ramstedt et al., 1987). The enzymes mannitol 1-P dehydrogenase (NADH-dependent),...

Importance Of Maintaining Fruit Growth

Fruit growth can be limited by several factors. First, most fruit crops produce many more flowers than the plants can support to maturity. There is natural drop of many fruit, but without grower intervention, tree fruit will still produce an overly large crop of very small fruit. The numerous fruit compete for limited resources from the tree (probably carbohydrates or nitrogen), and consequently fruit growth is inhibited. This is especially critical during the early cell division period. If competition can be limited by reducing the number of fruit at this time, final fruit size will be improved. Because of this response, considerable research is devoted to developing procedures for thinning fruit (reduction of fruit numbers to increase size). Thinning is a common and critical practice in production of most temperate tree fruit crops. temperature. Fruit growth in the early season during cell division appears to be quite sensitive to temperature, similar to many growth processes....

Pore Forming Toxins Mediated Infections

C. elegans is sensitive to Bt toxin CRY5B has been elucidated with the isolation of five C. elegans bre mutants (Bacillus toxin resistant), bre-1-bre-5. While bre-2-bre-5 encode four glycosyltransferases that appear to function in a single pathway required for the intestinal uptake of Cry5B, bre-1 encodes a protein with significant homology to a GDP-mannose 4,6-dehydratase, which catalyzes the first step in the biosynthesis of GDP-fucose from GDP-mannose (Barrows et al. 2007 Griffitts et al. 2001, 2003). Further analysis showed that the genetic mechanism for Bt toxin resistance in C. elegans entails the loss of certain glycolipid carbohydrates in the intestine (Griffitts et al. 2005).

The Pathway From Sucrose To Starch

The synthesis of rice starch has been studied in leaf chloroplast and endosperm amyloplast. The synthetic pathways were elucidated mostly by analyzing the levels of carbohydrates and enzyme activities among different tissues or organs at different physiological states. As described earlier, the enzymes ADPG-PPase, soluble and GBSS, BE and DE have been recognized as the enzymes involved in starch synthesis. Besides, we provided evidence to show that SuS was also a good provider of ADPG as described above. Among these enzymes, the genetic, biochemical and molecular biological studies were made most intensively on ADPG-PPase, SuS, GBSS and BE.

Evolution of Chloroplasts and the Import Machinery

More than a billion years ago, an ancestral free-living cyanobacterium was taken up by a eukaryotic cell (Olson 2006) . The resulting symbiosis gave the host cell access to valuable resources produced by photosynthesis (e.g., carbohydrates), and in return the cyanobacterium received a stable environmental milieu. Disadvantages of this arrangement included the tendency for oxidative damage to the organellar DNA and the absence of sexual recombination, rendering the plastome vulnerable to the accumulation of serious mutations (Lynch and Blanchard 1998 Martin and Herrman 1998) . To avoid this scenario, many genes were transferred from the

The Microtubule Associated Cellulose Synthase Compartment

The plasma membrane is the interface between the cytosol symplast and cell wall apoplast. The proteins on the PM are among the regulators of the components that enter and exit the cell. The cell wall is comprised of carbohydrates (e.g., cellulose, hemicelluloses, pectins), polyphenols (e.g., ligins), minerals (e.g., boron, silica), and sometimes waxes (e.g., suberin, cutin) that are secreted into the extracellular space. Once in the apoplast, these cell wall components often undergo modification due to developmental programs (e.g., cell enlargement, cell loosening in maternal tissues for pollen tube extension) or in response to biotic or abiotic stressors. These changes can be achieved by secretion of cell wall remodeling proteins, which may function enzymatically (cellulases, pectinase) or nonenzymatically (expansions) (reviewed in Lebeda et al. 2001 Sampedro and Cosgrove 2005).

Carbon nutrition of mycorrhizal fungi A External organic carbon sources

The very limited in vitro growth of hyphae from germinated spores of arbuscular mycorrhizal fungi may be somewhat stimulated by addition of nutrients to the medium. Although some early work indicated that sugars are inhibitory or non-stimulatory (see Hepper, 1987), it now appears that sucrose and glucose can be stimulatory at low concentrations (Siqueira et al., 1982 Carr et al., 1985 Siqueira and Hubbell, 1985). The optimum levels for stimulation of around 2 gkg ' fresh wt are similar to the concentrations of ethanol-soluble carbohydrates recorded in mycorrhizal leek roots (Amijee et al., 1990).

Carbon transfer from the host

The utilization of host carbon by the mycobiont can be demonstrated by exposing the shoots of the host plant to an atmosphere containing 14C02. Radioactivity is subsequently detected in the fungal tissue. This was first done for ectomycorrhiza by Melin and Nilsson (1957), for arbuscular mycorrhiza by Ho and Trappe (1973) and Bevege et al. (1975), and for ericoid mycorrhiza by Stribley and Read (1974). None of these studies provided information on the quantities of carbon transferred (see Section III). The dependency of the mycobiont on host photosynthate may be indirectly demonstrated by studying effects of treatments which reduce the production of photosynthates. Reduced root colonization by arbuscular fungi has thus been observed after defoliation (Daft and El-Giahmi, 1978 Same et al., 1983), lowered light intensity (Hayman, 1974 Johnson, 1976 Diederichs, 1982, 1983a Bethlenfalvay and Pacovsky, 1983 Tester et al., 1986), shortened photoperiod (Ferguson and Menge, 1982 Johnson et...

Low Nutritive Quality Of Douglasfir Foliage

Budworm (Clancy, 1991a, 1992a, 1992b, 2001 Clancy & King, 1993 Clancy et al., 1993). This is somewhat surprising given the tremendous variation in foliar concentrations of primary metabolites (i.e., nitrogen, carbohydrates, and minerals) in trees that is associated with the age of the tree and the leaves or needles, the genotype of the tree, and the environment the tree is growing in (Clancy et al., 1995). Nitrogen (N), or protein, is considered to be the most important nutrient for insect growth and survival (Mattson, 1980 Mattson & Scriber, 1987). However, the importance of N as a key nutrient is probably not strictly cause and effect, but is related to the strong link between N and many other important nutritional factors in plants (Clancy et al., 1995). The western spruce budworm's response to increased N in artificial diets was neither positively linear nor convex, and it was dependent on levels of minerals in the diets (Clancy, 1992a). Host plant N appears to determine the...

Seed Filling Phase III

Seeds cannot grow without a supply of assimilate so the photosynthetic productivity of the plant community during phase III is important. The total seed growth rate (g per m2 day-1) is directly affected by the assimilate supply (Table 6.2) (Egli, 1999) through effects on seed number and individual seed growth rate (Egli and Bruening, 2001). There are two sources of assimilate current photosynthesis and remobilization of stored carbohydrates. The potential contribution from stored carbohydrates (starch) is apparently relatively small in soybean (< 15 of total seed mass without adjusting for respiration losses in one series of experiments) (Egli, 1997) much less than that reported for wheat (model estimates suggest a contribution of 20-50 ) (Gent, 1994) and sunflower (Helianthus annuus L., 22-27 ) (Hall et al., 1989).

Engineering Soluble Sugars

For several crop species, soluble sugar content is much more important than that of starch. This is either because soluble sugars such as sucrose are major reserve carbohydrates (e.g. in sugar cane and sugar beet), or, as in fruit-bearing species, because sugar is an important component of taste. An increase in sugar content in strawberry has been achieved through fruit-specific antisense repression of AGPase. Transgenic strawberry fruits showed a decrease in starch content of approximately 50 and an increase in total soluble solids of up to 37 (Park et al., 2006). In general, relatively little is known at the biochemical or genetic level about the factors that control the rate of sucrose storage in sugar beet taproots or sugar cane nodes. This reflects the intractability of both crops using genetics and the difficulties in assessing storage metabolism at the biochemical level. Factors controlling sucrose accumulation in storage tissues are photoassimilate partitioning on the whole...

Proteomics Of Model Legume Medicago Truncatula

Analyzed soy proteins from seeds used in most clinical studies of hypercholesterolemia. Multiple samples used in Europe and the United States were analyzed by 2-DGE and MS 41 . The authors reported on the difference in soy proteins used in different clinical studies and discussed the implications of these results on the outcome of clinical studies. In another study, 422 proteins were identified in developing soybean seeds by 2-DGE and MS 42 . This research addressed the use of near-infrared reflectance spectroscopy in combination with chemical analysis for predicting protein and carbohydrate composition. Also, they reported a negative correlation between the seed storage protein G1 glycinin precursor and carbohydrates such as nonstarch polysac-charides and raffinose. As the first of its kind, recent research has applied comparative proteomics to analyze storage proteins in wild and cultivated soybean seeds 43 . The authors reported a higher degree of electrophoretic heterogeneity in...

Photoprotection and Photoinhibition in Winter

In evergreen species that downregulate photosynthesis during the winter, there is a strong correlation between the capacity for photosynthesis and predawn PS II efficiency within a species both during the winter and during the period of transition from winter through spring (closed circles in Fig. 4). On the other hand, there is no correlation between the two parameters under favorable conditions during the summer. Different needles or leaves can have very different capacities for photosynthesis while all have a high PS II efficiency (open circles in Fig. 4). This is true among sun-exposed needles and leaves, between sun (high capacity) and shade (low capacity) needles leaves of the same species, and among different species in which the capacity for photosynthesis varies greatly with differences in sink activity (utilization of the carbohydrates produced through photosynthesis for growth, storage, and respiration) but where PS II efficiency is equally high.

Shootroot distribution of carbon

Supply of labelled carbohydrates Carbon-14 labelled substrates may be fed directly to the plants by foliar application (L'Annunziata, 1979). This approach was used by Schumacher and Smucker (1985) to study effects of localized anoxia on carbon partitioning in Phaseolus vulgaris L. They applied U-14C sucrose directly to abraded areas of the leaves and the uptake of 14 C was quantified by removal of the source leaf and determination of the radiolabel in and on that leaf. Obviously these foliar applications of labelled compounds have a limited potential for the study of carbon balance as the pattern of translocation of photosynthates will be different from the normal phloem loading-unloading pattern. The methods may be of some use for studying the below-ground carbon balance but they find their main use when specifically labelled carbohydrates are used for analysis of metabolic pathways.

Particulate Organic Matter in Seagrass Sediments

The sources of POM in seagrass sediments are seston, macroalgae, epibionts, and seagrass detritus. The relative importance of one or another source depends on different processes including meadow production, export, and decomposition rates (see Chapter 7 for extensive explanations), eutrophication, coastal erosion, and overall water flow in the area. Studies of the contributions of different sources of organic matter in seagrass sediments indicate that a significant fraction of the organic matter is refractory (i.e. 56-84 in a P. oceanica meadow Danovaro, 1996), while only a minor proportion (18 ) is recovered in the biopolymeric fraction (lipids, carbohydrates, and proteins). Danovaro (1996) traced the origin of the labile fraction of particulate organic matter and found that 25 of this fraction derived from ben-thic microphytoplankton. Other studies, however, revealed the importance of seston as organic matter source in seagrass sediments. Gacia et al. (2002) estimated that 43 of...

Diversity of Habitats

All of the aquatic plants are primary producers. Their ability to fix carbon dioxide into carbohydrates by their light-driven photosynthetic reactions makes them the basis of the aquatic food chain. They are grazed upon and eaten, and, when they die, their structures are degraded by a huge variety of dependent organisms in the food web. These freshwater and ma-

Does Photoinhibition Limit the Carbon Available to the Plant

Continues to siphon off absorbed energy upon a return to non-excessive light conditions (e.g. Ball et al., 1991 Long et al., 1994 Melis, 1999 Werner et al., 2001 Zhu et al., 2004). This view has persisted for many years due primarily to the perspective that damage to D1 is suffered during photoinhibition (see Adir et al., 2003 for an historical review Hader, Huner et al., Nishiyama et al., Yokthongwattana and Melis, this volume) and that this lesion of the photosynthetic apparatus, or impairment of photosynthesis, must limit the supply of carbohydrates to the rest of the plant. Thus, there is considerable support for the view that photoinhibition is something that should be protected against (e.g. Endo and Asada, this volume), when in reality photoinhibition may be a means by which plants sustain photoprotection.

Role ofPlastids in Communication in AM

Plastids represent a plant cell compartment which plays a crucial role in plants because most of the cellular anabolic reactions take place there, both under normal conditions and in the case of stress. Apart from their capacity to produce carbohydrates through photosynthesis, plastids are involved in many biochemical pathways that are used to synthesize other elementary molecules and in the production of compounds somehow involved in cell-cell and or plant-plant communications (Bick and Lange 2003 Walter et al. 2002 Dudareva et al. 2005 Okada et al. 2007) (Fig. 1). There is an increasing amount of recent data in favor of the involvement of plastids in plant-fungal communication in the AM symbiosis. The possible involvement ofjasmonic acid (JA) in the process of mycorrhization was first inferred from leaf application experiments (Regvar et al. 1996 Ludwig-Muller et al. 2002). The amount of JA and its conjugates increases concomitantly in cells containing arbuscules through a...

An Integrated View of Photoprotection

Downregulation (or repression) of photosynthesis is a well-characterized response to conditions in which the supply of carbohydrates by source leaves exceeds the export and utilization of those sugars (Krapp and Stitt, 1995 Koch, 1996 Paul and Foyer, 2001). No one has ever suggested that rubisco or any of the other enzymes involved in the fixation and reduction of CO2 to sugars are damaged when their levels decrease under sink-limiting conditions. In addition, some components of photosynthetic electron transport and ATP synthesis are downregulated in response to sugar repression or sink-limiting conditions (Krapp and Stitt, 1995 Dijkwel et al., 1996). Furthermore, levels of the D1 protein decrease dramatically under low light when spinach leaves are fed glucose (Kilb et al., 1996). It seems only logical that, in a situation where carbohydrates are in abundance and the biochemistry of photosynthesis is downregulated, primary photochemistry and photosynthetic electron transport should...

The pathway of male gametophyte development

Despite the absence of symplastic connections between the sporophytic tissues of the anther and the developing microspores there is considerable evidence that interactions between the sporophytic and gametophytic generations are fundamentally important for the completion of pollen development. For example, the tapetum actively secretes and controls the deposition of proteins, lipids, carbohydrates and secondary metabolites, which are required for membrane synthesis, energy requirements and the elaboration of the unique pollen wall (for review see Pacini, 1990). The tapetum and anther loculus thus provide essential metabolites and a suitable environment in which differentiation of the microspores can occur. However, at later stages of both microspore and pollen development apparently normal differentiation can be completed in in vitro

CO2 fixed during the night is stored as malic acid

Nocturnal fixation of CO2 is catalyzed by phosphoenolpyruvate carboxylase, in the same way as in the metabolism of C4 plants and guard cells (Fig. 8.4). In many CAM plants the phosphoenolpyruvate required is generated from the degradation of starch, but in other plants soluble carbohydrates, such as sucrose (section 9.2) and fructanes (section 9.5), may also serve as carbon stores. Figure 8.17 shows a scheme of the CAM metabolism using starch as a carbon reservoir. The starch located in the chloroplasts is degraded to triose phosphate (section 9.1), which is then exported via the triose

Recognition Centers on Membrane Differences

Other researchers hypothesized that the induction of lamellocyte proliferation during sterile wounding may arise following recognition of damage to cell membranes at the wound site (Markus et al. 2005). Recent research in self-recognition has focused on the shielding of self membranes from encapsulation by membrane-bound carbohydrates and sialic acid. In other insects, host cells are more likely to be encapsulated when they lose these groups (Lackie 1980 Karacali et al. 2000). Binding requires recognition, making it more difficult to differentiate between mechanisms for each. General studies of encapsulation of beads with different attached functional groups have been performed in the moth Pseudoplusia inclu-dens, and have identified chemical properties and functional groups that make foreign matter more readily encapsulated. Specifically, foreign matter is readily encapsulated when it is cationic, or linked to sulfonic groups or some amino groups. Matter with attached carbohydrate...

Tree Growth and Symbiotic Associations

A. mangium can grow well on infertile soils, including those under grasslands, in part because of its association with symbiotic soil organisms, including mycorrhiza and Rhizobium (dela Cruz and Garcia 1991) (Plate 6.1). The tree roots provide these organisms with excess carbohydrates and

Deposition Of Protein

The developing endosperm is supplied with both carbohydrates and nitrogen by the maternal tissues. The nitrogen supplied by the maternal tissue is mobilized not only from nutrients taken up from the soil, but also from proteins that are hydrolyzed in senescing leaves and in the degrading parts of the ovule (95). Changes in the proteinase complement during leaf senescence may be related to the regulation of nitrogen mobilization in barley (96) cysteine proteinases have been shown to be involved in leaf senescence in both monocotyledonous and dicotyledonous plants (97, 98). Two proteinases, nucellin (99) and nucellain (100), have been identified to be also present during autolysis of the nucellus in barley. Nucellin is an aspartic proteinase, whereas nucellain, localized in the cell wall, shows homology to an vacuolar-processing enzyme of castor bean (Ricinus communis). The exact hydrolytic roles of these proteases, in leaves or nucella, have however not yet been determined. Therefore...

Starch and sucrose are the main products of CO2 assimilation in many plants

In most crop plants (e.g., cereals, potato, sugar beet, and rapeseed), carbohydrates are stored in the leaves as starch and exported as sucrose to other parts of the plants such as the roots or growing seeds. CO2 assimilation in the chloroplasts yields triose phosphate, which is transported by the triose phosphate-phosphate translocator (section 1.9) in counter-exchange for phosphate into the cytosol, where it is converted to sucrose, accompanied by the release of inorganic phosphate (Fig. 9.1). It is essential that this phosphate is returned, since phosphate deficiency in the chloroplasts would cause photosynthesis to die down. Part of the triose phosphate generated by photosynthesis is converted in the chloroplasts to starch, serving primarily as a reserve for the following night period.

Sourcesink Relationships

There is strong competition between the different parts of the vine, and the bunches are weak sinks until ripening commences (Hale and Weaver 1962). Post-veraison, carbohydrates are imported into the berry at a higher rate and clusters become very competitive sinks. However, shoot growth during ripening may slow sugar accumulation in the berry. At any stage, berry growth and development are affected by modification of the carbohydrate supply to the berry. These modifications are brought about by adjusting the number of bunches in relation to the leaf area in order to achieve the required grape maturation. With regard to leaf removal, a large decrease in leaf area just after fruit set can induce a reduction in berry growth. In this situation, Kaps and Cahoon (1992) showed that berry weight at maturity is related to the ratio leaf area fruit weight. Noteworthy in our dataset for fresh weight and berry water content (Fig. 2a,c), val

Plant Mechanisms to Cope with Cadmium

At root level, plants have developed extracellular strategies to avoid Cd toxicity and especially interesting is the relationship with mycorrhizal fungus (Jentschke et al. 1999 Courbot et al. 2004 Janouskova et al. 2006) or with some bacterial strains from the rhizosphere which can reduce Cd concentration in the shoot of the hyperaccumulators A. halleri, and which highlights the importance of plant-microbe interactions in Cd toxicity (Farinati et al. 2011). Additionally, the evaluation of interactions between heavy metal contamination and beneficial rhizosphere microbes adapted to the contaminated soils and their effects on plant development has shown that the microbes are not only able to grow but also to improve plant development under polluted conditions (Azcon et al. 2010). Interestingly, it seems that toxicity of heavy metal to microorganisms is due, in part, to oxidative stress, and it has been hypothesised that the metal resistance of microorganisms and their beneficial effect...

Berry Growth And Development

Water availability to the plant is an important factor in organ enlargement, but it also interacts closely with photosynthesis and berry carbohydrates supply (Ollat et al. 2002). Berry size is affected by water deficit from anthesis to maturity however, final berry size is more influenced by water deficits between flowering and veraison (Becker and Zimmermann 1984, Poni et al. 1994, Ojeda et al. 2001). Ojeda et al. (2001) observed that water limitation during the first growth phase of the berry (before veraison) does not affect cell division but decreases cell volume. The results show that vine water status is a more important factor than leaf area with regards to determining final berry size (Fig. 2).

Propagation of systemic RNA silencing 3341 Longdistance movement of RNA silencing

Long-distance transport occurs in the phloem. Long-distance movement of molecules in plants can occur through the xylem and the phloem conduits, both of which are restored upon graft junctions. However, only the phloem distributes the photoassimilates throughout the plant, following a specific pattern whereby mature, photosynthetically autonomous organs export - but do not import - carbohydrates. These tissues are said to be 'source' of phloem. Conversely, import of carbohydrates occurs in the new growth (meristems, primordia, young leaves), which has not yet reached photosynthetic autonomy and is therefore a 'sink' of phloem. The intermediate situation is the sink-to-source transition, which typically occurs in leaves in a basipetal direction down the leaf axis towards the petiole.

Nitrate assimilation also takes place in the roots

As mentioned, nitrate assimilation occurs in part, and in some species even mainly, in the roots. NH4+ taken up from the soil is normally fixed in the roots. The reduction of nitrate and nitrite as well as the fixation of NH4+ proceeds in the root cells analogously to that of the mesophyll cells. However, in the root cells the necessary reducing equivalents are supplied exclusively by oxidation of carbohydrates. In roots the reduction of nitrite and the subsequent fixation of NH4+ (Fig. 10.8) occur in the leucoplasts, a differentiated form of plastids (section 1.3).

Other Carbon Fates Translocation and Seagrass Exudates

Retranslocation of carbon resources from senescent to young leaves, between above- and below-ground organs (e.g. Alcoverro et al., 2001) or between adjacent shoots (Marba et al., 2002), are mechanisms apparently used by seagrasses for an efficient use of their resources. A maximum of 11 of the carbon gain by the P. oceanica leaves can be accumulated as non-structural carbohydrates in the whole plant (above- and below-ground organs, Alcoverro et al., 2001). The fraction of this amount that is actually stored in roots and rhizomes cannot be easily determined at this time due to different criteria by different authors concerning the size of the living below-ground compartment. The relevance of this possible fate for leaf carbon is also difficult to ascertain since the carbon accumulated during periods of positive plant carbon balance can be later mobilized to support the growth of new leaves during periods of negative plant carbon balance (Alcoverro et al., 2001). It has been shown that...

Necessity Of Photoautotrophic Micropropagation In Woody Transplant Production

Photoautotrophic micropropagation requires the growth of chlorophyllous explants on a sugar-free medium under pathogen-free and favorable in vitro environmental conditions, which enable plants in vitro to photosynthesize and produce their own carbohydrates for growth. A photoautotrophic micropropagation system with the improvement of in vitro aerial and root zone environments has significantly enhanced the growth of plants in vitro, increased the multiplication rate and thus, shortened the multiplication period of plants in vitro (Kozai et al., 1988).

Uptake and loss of carbon dioxide

Photosynthesis is the process by which plants absorb light energy and convert atmospheric CO2 to carbohydrates that are available for further biochemical processes. In parallel, during daylight hours leaves also release CO2 - through mitochondrial respiration as well as photorespiration, the latter linked to the oxygenase activity of the enzyme ribulose-bisphosphate carboxylase-oxygease (Rubisco) - so that there is a net CO2 uptake, termed as apparent net photosynthesis. Net photosynthesis is regulated simultaneously by many factors.

Thinlayer chromatography TLC

TLC on silica gel gives similar resolution to PC but on a smaller area (typically 20 x 20cm as opposed to 46 x 57cm) (Fry 2000). TLC is more useful for large oligosaccharides, including those that bind paper (MLG-, cello- and manno-oligosaccharides). Suitable solvents include butan-1-ol acetic acid water (2 1 1) and propan-1-ol nitromethane water (5 2 3). A useful stain for carbohydrates on silica gel is freshly prepared 0.5 (w v) thymol in 96 ethanol H2SO4 (20 1 v v) - the plate is quickly dipped in this solution, dried, and then heated in an oven at 105 C for 3-6 min.

The end product of nitrate assimilation is a whole spectrum of amino acids

As described in Chapter 13, the carbohydrates formed as the product of CO2 assimilation are transported from the leaves via the sieve tubes to various parts of the plants. The transport forms of the carbohydrates are sucrose, sugar alcohols (e.g., sorbitol), or raffinoses, depending on the species. There are no such special transport forms for the products of nitrate assimilation. All amino acids present in the mesophyll cells are exported via the sieve tubes. Therefore the sum of amino acids can be regarded as the final product of nitrate assimilation. Synthesis of these amino acids takes place mainly in the chloroplasts. The pattern of the amino acids synthesized varies largely, depending on the species and the metabolic conditions. In most cases glutamate and glutamine represent the major portion of the synthesized amino acids. Glutamate is exported from the chloroplasts in exchange for malate and glutamine in exchange with glutamate (Fig. 10.6). Also, serine and glycine, which are...

Paper e lectrophoresis PE

High-voltage PE (Fry 2000) is a surprisingly little-used technique that can, however, give excellent resolution of charged carbohydrates e.g. amino sugars, uronic acids, aldonic acids, aldaric acids, sugar phosphates and NDP sugars (e.g. Green & Fry 2005- Sharples & Fry 2007- Takeda et al. 2008 see also Even neutral sugars can be analysed by PE if a borate buffer is used, with which the sugar revers-ibly forms an anionic borate ester (e.g. O'Looney & Fry 2005). Electrophoretic

Immobilization and Movement of Nutrients by Fungi

During the course of decomposition, mineral nutrients are sequestered by decomposer soil organisms by being incorporated into the organism's biomass. The residence time of these elements is usually equivalent to the turnover time (lifespan) of that organism. During this period, the element is not in a soluble form in the soil solution, but is immobilized in microbial tissue. The amount of accumulation within the fungal component varies among ecosystems, depending on the chemical composition of the plant parts available for decomposition and the main fungal groups involved in the process. Shorter-lived, ephemeral molds, utilizing simple carbohydrates, thus have lower investment in biomass than longer-lived basidiomycetes growing on woody resource the potential accumulation in basidiomycetes is therefore greater. Unlike bacteria, fungi are larger organisms and their rate of turnover is lower, particularly in the long-lived Basidiomycotina. A discussion of the role of basidiomycetes in...

Sugar Calories and Energy

In addition to its flavor, which was the original reason for its popularity, sugar supplies an important nutritional factor in the form of energy. Sugar contains four calories per gram and one teaspoon of white table sugar (sucrose) weighs about 3.5 grams. The basic calorie requirement for maintaining life (respiration, circulation, muscle tone) varies between 750 and 1,630 per day in a state of complete rest. Intense muscular effort may require upwards of 7,000 calories during the day. Carbohydrates are an essential component of the human diet, and Recommended Dietary Allowances (RDAs) for nutrients in the American diet have been established by the National Academy of Sciences. The RDAs suggest that the average dietary energy intake (in calories) should consist of 10 to 15 percent protein, 35 to 40 percent fat, and 45 to 50 percent carbohydrates. Carbohydrates, therefore, contribute the major part of the available energy in the human diet. In less-developed areas, it is not unusual...

The Plasma Membrane and the Cell Wall

Abstract Plant cell walls are among the features that distinguish plants from animals. The cell wall contributes to internal cellular turgor pressure while offering protection to the cell from external threats. The cell wall is also flexible, and its content and structures are modulated according to growth and tropisms. A typical plant cell wall is primarily composed of carbohydrates synthesized either at the plasma membrane (PM) or in the trans-Golgi network cellulose and callose are produced at the PM, whereas the matrix polysaccharides, i.e., pectins and hemi-celluloses, are synthesized in the Golgi apparatus and are subsequently transported across the PM via exocytosis. The wall also contains enzymes and structural glycoproteins. The cell wall is formed by independent and coordinated mechanisms based on physical properties and self-assembly, as well as the action of cell wall-modifying enzymes. Thus, the plant cell wall physiology is dynamic and includes coordinated sugar...

The cell wall as a potential source of chemical signals

Initial interest in the potential signalling function of AGPs was aroused by the finding that epitopes of specific AGP-associated carbohydrates occurred in tissue-specific patterns. For example, Roberts and colleagues demonstrated that an AGP recognised by the antibody JIM13 is initially expressed exclusively in metaxylem

The arbuscular mycorrhiza is widespread

The arbuscular mycorrhiza has been detected in more than 80 of all terrestrial plant species. In this symbiosis the fungus penetrates the cortex of plant roots by a plant controlled process and forms a network of hyphae, which protrude into cortical cells and form treelike invaginations, termed arbuscules (Fig. 11.9), or form hyphal coils. The boundary membranes of fungus and host remain intact. The arbuscules form a large surface, enabling an efficient exchange of compounds between the fungus and the host. The fungus delivers phosphate, nitrate, K+ ions, and water, and the host delivers carbohydrates. The arbuscules have a lifetime of less than two weeks, but the subsequent degeneration

Integration Of Processes In The Whole Plant Bottomup

Similar models, but of slightly greater complexity, are also able to explain observations of preferential root growth into nutrient-rich soil patches. Van Oijen et al. (1986) implemented the following mechanism in their model The root system was divided into two parts, one in N-rich medium, and the other in N-poor medium. Growth rate of each root part, and of the shoot, depended on the concentrations of N and C substrate in that plant part, and transport between root parts was only possible via the shoot. N uptake of the root in poor medium was obviously hampered, so growth of this root depended fully on organic N received from the shoot in the phloem. This allowed some growth, but at low rate, leading to accumulation of unused carbohydrates and subsequent inhibition of the Munch-type phloem inflow. High rates of phloem import, and growth, were maintained in the root part growing in rich medium. This model was able to account with great accuracy for observations on maize roots in...

Chun Hu David D Kitts and Jerzy Zawistowski

Living organisms are exposed to 20.93 oxygen in air, which contributes to a dependency on biological oxidation reactions as a source of energy required for natural growth and metabolism. Under normal conditions, 2 of the oxygen consumed by mitochondria is incompletely reduced, thus resulting in the production of oxygen radicals (Boveris and Chance, 1973). If mitochondria electron transport is compromised, the percentage of oxygen incompletely reduced will increase. There is a potential, therefore, for a relatively small percentage of oxygen derived from systemic respiration to be transformed to bioactive agents, which in turn can ultimately lead to peroxidation reactions of cellular constituents that are composed of nucleic acids, lipids, proteins, and carbohydrates. In addition to endogenously derived reactive oxygen species (ROS), living organisms can also be exposed to ROS derived from exogenous sources such as environmental exposure to ultraviolet light, smoking, and pollution....

Phytochemical 1deoxynojirimycin of Morus alba L mulberry

A human study conducted in Japan reported that food grade extract of mulberry is a potent inhibitor of enzyme glucosidase. The enzyme regulates the digestion of carbohydrates. The activity is due to the presence of 1-deoxynojirimycin (DNJ), an antibiotic compound present in mulberry leaves. The study indicated that the single oral administration of 0.8 and

Obligate Hemiparasite to Holoparasite Loss ofAutotrophic Functions

The increasing use of and dependence on host carbohydrates allows a relaxation in parasite photosynthesis. This is accompanied in many cases by rearrangements and deletions to the parasite chloroplast genome (Morden et al. 1991 Bommer et al. 1993 Delavault et al. 1996). Of course, once the chloroplast genome has undergone extensive deletions, the parasite is fixed as a heterotrophic holoparasite.

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