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511.
It is indicated here that organic macro molecules in the soil are aggregated due to bonds, presumably hydrogen bonds, formed
in the presence of water. When the soil is dried, this structure is broken and the stability of the organic matter decreases.
This process is not an instantaneous process and apparently some relaxation period is needed for a complete dispersion of
the organic matrix. An appreciable fraction of the organic molecules is hindered, even from contact with the solution in the
aggregated structure, as indicated by the lower acidity in the wet soil. This steric hinderence seems to be one of the important
factors contributing to the stability of humic compounds. 相似文献
512.
Summary Antibodies with specificity towards abscisic acid (ABA) were produced in rabbits. These antibodies were used for assaying ABA by the inhibition of inactivation of modified bacteriophage. For this assay conjugates of ABA with bacteriophage T4 were prepared and characterized. Such chemically modified bacteriophages were completely inactivated by the specific anti-ABA serum and this inactivation was inhibited by free ABA. The identification and quantitative determination of ABA in plant extracts by this method are demonstrated and the method is compared with a common bioassay. 相似文献
513.
Yoram Shechter Dana Elias Ruth Maron Irun R. Cohen 《Journal of cellular biochemistry》1983,21(2):179-185
We immunized mice with insulin and found that those strains that develop insulin antibodies subsequently produce insulin-like activity in amount equivalent to 300–400 ng insulin per ml serum. The activity was due exclusively to IgG2 antibodies. Bioactivity could be blocked efficiently by insulin antibodies from guinea pigs and from mice. The active IgG2 also displaced labeled insulin from fat cells. Preliminary in vivo studies have indicated that the appearance of insulin-like antibodies in the mouse resulted in abnormal glucose homeostasis and “down regulation” of insulin receptors. These results indicate that immunization to insulin can initiate an idiotype-anti-idiotype network resulting in antibodies to the hormone receptor. 相似文献
514.
Gilad Liberman Jennifer I.C. Benichou Yaakov Maman Jacob Glanville Idan Alter Yoram Louzoun 《Nucleic acids research》2016,44(5):e46
Incremental selection within a population, defined as limited fitness changes following mutation, is an important aspect of many evolutionary processes. Strongly advantageous or deleterious mutations are detected using the synonymous to non-synonymous mutations ratio. However, there are currently no precise methods to estimate incremental selection. We here provide for the first time such a detailed method and show its precision in multiple cases of micro-evolution. The proposed method is a novel mixed lineage tree/sequence based method to detect within population selection as defined by the effect of mutations on the average number of offspring. Specifically, we propose to measure the log of the ratio between the number of leaves in lineage trees branches following synonymous and non-synonymous mutations. The method requires a high enough number of sequences, and a large enough number of independent mutations. It assumes that all mutations are independent events. It does not require of a baseline model and is practically not affected by sampling biases. We show the method''s wide applicability by testing it on multiple cases of micro-evolution. We show that it can detect genes and inter-genic regions using the selection rate and detect selection pressures in viral proteins and in the immune response to pathogens. 相似文献
515.
Eran Amichai Eran Levin Noga Kronfeld-Schor Uri Roll Yoram Yom-Tov 《Mammalian Biology》2013,78(2):94-103
We used radio-telemetry, observations and physiological measurements to study the basic biology and energetic strategies of Asellia tridens in northern Israel from 2009 to 2010. Between late May and early November, the bats occupied abandoned man-made structures in this area. Parturition occurred between late June and mid-July, and juveniles were independent by late August. A. tridens foraged near the roost in a vegetation-rich, cluttered background environment, catching insects flying close to vegetation. Its diet was diverse, with Coleoptera, Heteroptera, Diptera and Lepidoptera being the main diet components. During summer, males and females differed in their foraging patterns and energetic strategies: Lactating females departed for more frequent foraging bouts than males, and maintained euthermy throughout the day, while males became torpid on a daily basis. 相似文献
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The synthesis of carrier-free β-32P-ribonucleosides triphosphate in almost quantitative yields is described. The procedures are based on a polynucleotide phosphorylase-catalyzed phosphorolysis of either poly- or oligoribonucleotides with carrier-free 32P-inorganic phosphate, coupled with a pyruvate kinase-catalyzed phosphorylation of the resulting β-32P-nucleoside diphosphate. 相似文献
518.
Yoram Yom‐Tov Eli Geffen 《Biological reviews of the Cambridge Philosophical Society》2011,86(2):531-541
Geographical and temporal variations in body size are common phenomena among organisms and may evolve within a few years. We argue that body size acts much like a barometer, fluctuating in parallel with changes in the relevant key predictor(s), and that geographical and temporal changes in body size are actually manifestations of the same drivers. Frequently, the principal predictors of body size are food availability during the period of growth and ambient temperature, which often affects food availability. Food availability depends on net primary productivity that, in turn, is determined by climate and weather (mainly temperature and precipitation), and these depend mainly on solar radiation and other solar activities. When the above predictors are related to latitude the changes have often been interpreted as conforming to Bergmann's rule, but in many cases such interpretations should be viewed with caution due to the interrelationships among various environmental predictors. Recent temporal changes in body size have often been related to global warming. However, in many cases the above key predictors are not related to either latitude and/or year, and it is the task of the researcher to determine which particular environmental predictor is the one that determines food availability and, in turn, body size. The chance of discerning a significant change in body size depends to a large extent on sample size (specimens/year). The most recent changes in body size are probably phenotypic, but there are some cases in which they are partly genetic. 相似文献
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