Secrets of the Deep Sky
Organisms are normally subjected to daily alternations of light and darkness and often exhibit rhythmic behaviour in association with these changes. Many of the rhythmic responses to day and night continue even in a constant light or dark environment, at least for a period of time. An example of such rhythms is seen in the daily 'sleep' movements of leaves. In many plants, leaves are held more or less horizontally during the day and assume an upward or downward position at night. However, in 1729, the astronomer De Mairam observed that the movements persisted (at least for a time)
Perhaps the first observation of a circadian rhythm associated with a plant was made by Androsthenes, scribe to Alexander the Great, who noticed that the leaves of certain trees were elevated by day and drooped at night. More recently, an eighteenth century French astronomer, Jean de Mairan, observed that the leaves of certain sensitive plants, probably mimosa, continued to open and close even during long periods of darkness. In the first half of the twentieth century the German plant physiologist Erwin Bunning made detailed observations of the movement of bean leaves. He confirmed that the leaves continued to move up and down in constant darkness, and established that the period was 25.4 hours.
Pollen physiology has attracted the attention of plant breeders and horticulturists for plant improvement programmes ever since the discovery of the pollen tube by Giovanni Batista Amici (1924), an Italian astronomer and mathematician, while examining the papillate stigma of Portulaca oleracea. Physiological studies have mainly centred round pollen germination, storage, and on the artificial induction of pollen sterility in cultivated plants, to be of benefit in large-scale hybridization programmes. Very scanty information is available in pollen germination of Indian trees. An interesting development in the pollen studies is the study of the influence of pollen physiology on the mode of pollination and breeding systems of plants. In pollen physiology, the various aspects normally studied are pollen chemistry, pollen storage, pollen viability, pollen germination in vitro and in vivo.
Proteomics as a Toolbox to Study the Metabolic Adjustment of Trees During Exposure to Metal Trace Elements
Although often regarded as a recent, industry-related problem, environmental pollution with heavy metals and its link with human activity predate the industrial age (Cooke et al. 2009). Nonetheless, the increasing pressure contributed by the growing world population makes environmental pollution, which results in the deterioration of available natural resources and or threatening the natural habitat of organisms, a major concern for current and future generations. Although everyone has their own clear personal idea of what constitutes pollution, it is particularly difficult to define. While a streetlight for most of us is an aid in helping to get home safely, the amateur astronomer will consider it as light pollution. Therefore, thresholds, i.e., values above which the concentration of a specific component becomes a problem in specific conditions, have been established by national or supranational legislation. Some metal trace elements, such as Zn, Fe, Cu, Mn, Mb and Co, are essential...
Through this ebook, you are going to learn what you will need to know all about the telescopes that can provide a fun and rewarding hobby for you and your family!