Productivity, organism size, and the trophic structure of the major terrestrial biomes

I present a hypothesis suggesting that terrestrial biomes' productivity determines the size of the major organisms and plant physiognomy in them and consequently determines their trophic structure. I suggest a more comprehensive set of patterns over current hypotheses, which consider productivity alone. Based on my hypothesis, I predict that the number of trophic levels decreases with increasing productivity from four in hot deserts to two in productive grasslands and that there are three to four trophic levels in all types of forested biomes. I also suggest that productivity is the limiting factor for the number of trophic levels at the lower end of the terrestrial productivity gradient, herbivore size is the limiting factor at intermediate productivities, and plant physiognomy is the limiting factor in the high productivity range. This contradicts existing hypotheses that predict either an increase (Am Nat 118:240–261, 1981; Am Nat 155:703–723, 2000) or no change (Am Nat 142:379–411, 1993) in the number of trophic levels with the increase in biome productivity.     

Insoluble antibody column for isolation and quantitative determination of gibberellins

A column that specifically binds gibberellins was prepared bycovalent binding of anti-GA antibodies to Sepharose. By usingsuch an immunoadsorbent column, radio-immunoassay for quantitativedetermination of gibberellins was developed. Using this method,diffusible GA from apices of etiolated pea seedlings was isolatedin one step and determined quantitatively. (Received March 29, 1974; )     

A Quantitative Study of the Ca2+/Calmodulin Sensitivity of Adenylyl Cyclase in Aplysia, Drosophila, and Rat

Studies in Aplysia and Drosophila have suggested that Ca2+/calmodulin-sensitive adenylyl cyclase may act as a site of convergence for the cellular representations of the conditioned stimulus (Ca2+ influx) and unconditioned stimulus (facilitatory transmitter) during elementary associative learning. This hypothesis predicts that the rise in intracellular free Ca2+ concentration produced by spike activity during the conditioned stimulus will cause an increase in the activity of adenylyl cyclase. However, published values for the Ca2+ sensitivity of Ca2+/calmodulin-sensitive adenylyl cyclase in mammals and in Drosophila vary widely. The difficulty in evaluating whether adenylyl cyclase would be activated by physiological elevations in intracellular Ca2+ levels is in part a consequence of the use of Ca2+/EGTA buffers, which are prone to several types of errors. Using a procedure that minimizes these errors, we have quantified the Ca2+ sensitivity of adenylyl cyclase in membranes from Aplysia, Drosophila, and rat brain with purified species-specific calmodulins. In all three species, adenylyl cyclase was activated by an increase in free Ca2+ concentration in the range caused by spike activity. Ca2+ sensitivity was dependent on both calmodulin concentration and Mg2+ concentration. Mg2+ raised the threshold for adenylyl cyclase activation by Ca2+ but also acted synergistically with Ca2+ to activate maximally adenylyl cyclase.     

Climatological correlates for body size of five species of Australian mammals

Size variation of body and skull of five species of Australian mammals (echidna, Tachyglossus aculeatus ; brush-tail possum, Trichosurus vulpecula ; eastern grey kangaroo, Macropus giganteus ; western grey kangaroo, M. fuliginosus ; red kangaroo, M. rufus ), is related to climatic factors. All five species show trends in body size that conform with Bergmann's rule, individuals from colder environments being larger than those from warmer areas. The western and eastern grey kangaroos also conform with Allen's rule, the relative size of their extremities being large in warmer areas. In four of the five species (not the red kangaroo) body size is also correlated with indices of biomass productivity. However, since biomass productivity and ambient temperature are related to some extent, it is difficult to separate the effects of these factors.     

On the limited recognition of inorganic surfaces by short peptides compared with antibodies

The vast potential applications of biomolecules that bind inorganic surfaces led mostly to the isolation of short peptides that target selectively specific materials. The demonstrated differential affinity toward certain surfaces created the impression that the recognition capacity of short peptides may match that of rigid biomolecules. In the following, we challenge this view by comparing the capacity of antibody molecules to discriminate between the (100) and (111A) facets of a gallium arsenide semiconductor crystal with the capacity of short peptides to do the same. Applying selection from several peptide and single chain phage display libraries, we find a number of antibody molecules that bind preferentially a given crystal facet but fail to isolate, in dozens of attempts, a single peptide capable of such recognition. The experiments underscore the importance of rigidity to the recognition of inorganic flat targets and therefore set limitations on potential applications of short peptides in biomimetics. Copyright © 2014 European Peptide Society and John Wiley & Sons, Ltd.     

Weather conditions and visits to the medical wing of emergency rooms in a metropolitan area during the warm season in Israel: a predictive model

Global climate changes affect health and present new challenges to healthcare systems. The aim of the present study was to analyze the pattern of visits to the medical wing of emergency rooms (ERs) in public hospitals during warm seasons, and to develop a predictive model that will forecast the number of visits to ERs 2 days ahead. Data on daily visits to the ERs of the four largest medical centers in the Tel-Aviv metropolitan area during the warm months of the year (April–October, 2001–2004), the corresponding daily meteorological data, daily electrical power consumption (a surrogate marker for air-conditioning), air-pollution parameters, and calendar information were obtained and used in the analyses. The predictive model employed a time series analysis with transitional Poisson regression. The concise multivariable model was highly accurate (r ² = 0.819). The contribution of mean daily temperature was small but significant: an increase of 1°C in ambient temperature was associated with a 1.47% increase in the number of ER visits (P < 0.001). An increase in electrical power consumption significantly attenuated the effect of weather conditions on ER visits by 4% per 1,000 MWh (P < 0.001). Higher daily mean SO₂ concentrations were associated with a greater number of ER visits (1% per 1 ppb increment; P = 0.017). Calendar data were the main predictors of ER visits (r ² = 0.794). The predictive model was highly accurate in forecasting the number of visits to ERs 2 days ahead. The marginal effect of temperature on the number of ER visits can be attributed to behavioral adaptations, including the use of air-conditioning.     

Free Sulfhydryl Groups in Ripening Tomato fruits

The content of free sulfhydryl (SH) groups in tomato (Lycopersiconesculentum Mill.) fruits was determined. The levels of thesegroups in different cultivars increased as the fruit ripened,either on the vine or in storage. The compounds containing theseSH groups were dialyzable and were ascribed to be cysteine andglutathione. The possible significance of these findings isdiscussed. (Received January 5, 1981; Accepted March 20, 1981)