STUDIES ON SALT ACTION : X. THE INFLUENCE OF ELECTROLYTES UPON THE VIABILITY AND ELECTROPHORETIC MIGRATION OF BACTERIUM COLI.

1. The strain of Bacterium coli used in these experiments multiplies in distilled water at pH 6.0 and pH 8.0 and in Ringer-Locke solution at pH 6.0. Under all the other conditions studied the numbers decrease with the passage of time. 2. The electrophoretic charge of the cells is highest in distilled water at pH 6.0 and pH 8.0. Under all other conditions studied the velocity of migration is decreased, but the decrease is immediate and is not affected by more prolonged exposure. 3. A strongly acid solution (pH 2.0) causes a rapid death of the cells and a sharp decrease in electrophoretic charge, sometimes leading to complete reversal. 4. A strongly alkaline solution (pH 11.0) is almost as toxic as a strongly acid one, although in distilled water the organisms survive fairly well at this reaction. Electrophoretic charge, on the other hand, is only slightly reduced in such an alkaline medium. 5. In distilled water, reactions near the neutral point are about equally favorable to both viability and electrophoretic charge, pH 8.0 showing slightly greater multiplication and a slightly higher charge than pH 11.0. In the presence of salts, however, pH 8.0 is much less favorable to viability and somewhat more favorable to electrophoretic charge than is pH 6.0. 6. Sodium chloride solutions, in the concentrations studied, all proved somewhat toxic and all tended to depress electrophoretic charge. Very marked toxicity was, however, exhibited only in a concentration of .725 M strength or over and at pH 8.0, while electrophoretic migration velocity was only slightly decreased at a concentration of .0145 M strength. 7. Calcium chloride was more toxic than NaCl, showing very marked effects in .145 M strength at pH 8.0 and in 1.45 M strength at pH 6.0. It greatly depressed electrophoretic charge even in .0145 M concentration. 8. Ringer-Locke solution proved markedly stimulating to the growth of the bacteria at pH 6.0 while at pH 8.0 it was somewhat toxic, though less so than the solutions of pure salts. It depressed migration velocity at all pH values, being more effective than NaCl in this respect, but less effective than CaCl₂. 9. It would appear from these experiments that a balanced salt solution (Ringer-Locke''s) may be distinctly favorable to bacterial viability in water at an optimum reaction while distinctly unfavorable in a slightly more alkaline solution. 10. Finally, while there is a certain parallelism between the influence of electrolytes upon viability and upon electrophoretic charge, the parallelism is not a close one and the two effects seem on the whole to follow entirely different laws.     

Transient behavior of T-cell hybridomas in response to changes in metabolite concentrations in continuous culture.

Effects of pulse and step changes in major metabolite concentrations such as glucose, glutamine, lactic acid, and ammonium on behavior of T-cell hybridomas in continuous culture were investigated in order to develop a strategy to maximize specific rate of lymphokine formation. Step increases in glucose, lactic acid, and ammonium concentrations decreased, and a step increase in glutamine concentration increased, the specific rate of lymphokine formation. Effects of step and pulse changes on specific rates of glucose and glutamine consumption and viability of cells were also investigated.     

Growth and product inhibition kinetics of T-cell hybridomas producing lymphokines in batch and continuous culture.

The kinetics of growth and lymphokine formation by T-cell hybridomas were investigated in batch and continuous culture. Product inhibitions by ammonia and lactic acid were considered in the proposed model and experimental data were used to determine the kinetic and inhibition constants. The effect of dilution rate on specific substrate consumption and product formation rates was investigated.     

What's inside a sauropod limb? First three-dimensional investigation of the limb long bone microanatomy of a sauropod dinosaur,Nigersaurus taqueti (Neosauropoda,Rebbachisauridae), and implications for the weight-bearing function

Various terrestrial tetrapods convergently evolved to gigantism (large body sizes and masses), the most extreme case being sauropod dinosaurs. Heavy weight-bearing taxa often show external morphological features related to this condition, but also adequacy in their limb bone inner structure: a spongiosa filling the medullary area and a rather thick cortex varying greatly in thickness along the shaft. However, the microanatomical variation in such taxa remains poorly known, especially between different limb elements. We highlight for the first time the three-dimensional microstructure of the six limb long bone types of a sauropod dinosaur, Nigersaurus taqueti. Sampling several specimens of different sizes, we explored within-bone, between-bones, and size-related variations. If a spongiosa fills the medullary area of all bones, the cortex is rather thin and varies only slightly in thickness along the shaft. Zeugopod bones appear more compact than stylopod ones, whereas no particular differences between serially homologous bones are found. Nigersaurus' pattern appears much less extreme than that in heavy terrestrial taxa such as rhinoceroses, but is partly similar to observations in elephants and in two-dimensional sauropod data. Thus, microanatomy may have not been the predominant feature for weight-bearing in sauropods. External features, such as columnarity (shared with elephants) and postcranial pneumaticity, may have played a major role for this function, thus relaxing pressures on microanatomy. Also, sauropods may have been lighter than expected for a given size. Our study calls for further three-dimensional investigations, eventually yielding a framework characterizing more precisely how sauropod gigantism may have been possible.     

Grooming-at-a-distance by exchanging calls in non-human primates

The ‘social bonding hypothesis'' predicts that, in large social groups, functions of gestural grooming should be partially transferred to vocal interactions. Hence, vocal exchanges would have evolved in primates to play the role of grooming-at-a-distance in order to facilitate the maintenance of social cohesion. However, there are few empirical studies testing this hypothesis. To address this point, we compared the rate of contact call exchanges between females in two captive groups of Japanese macaques as a function of female age, dominance rank, genetic relatedness and social affinity measured by spatial proximity and grooming interactions. We found a significant positive relationship between the time spent on grooming by two females and the frequency with which they exchanged calls. Our results conform to the predictions of the social bonding hypothesis, i.e. vocal exchanges can be interpreted as grooming-at-a-distance.     

Microsatellite markers for <Emphasis Type="Italic">Caesalpinia echinata</Emphasis> Lam. (Brazilwood), a tree that named a country

Caesalpinia echinata, commonly known as Pau-brasil (Brazilwood), the famous tree that named Brazil is native to the Atlantic forest. Men extensively exploited it ever since discovery and colonial times due to its value as a source of red dye. As a consequence, Brazilwood is a threatened species with populations reduced to small forest fragments. Ten polymorphic microsatellite loci were developed from an enriched genomic library. Using fluorescently-labeled primers, a total of 83 alleles were found after analyzing a sample of 44 trees. These high genetic information content markers should allow detailed investigations of mating systems, gene flow, population structure and paternity in natural populations.     

Quantifying structural changes and stoichiometry of protein interactions using size and density profiling

Summary The use of Dual Polarisation Interferometry, and emerging analytical biophysical technique, is described for the determination of the optogeometrical properties (thickness and density) at high resolution of adsorbed protein layers at the solid-liquid interface. The technique has been used to quantify, in real time and at subatomic resolution, the structural changes occurring in two well-characterised protein interaction systems, an antibody-antigen interaction and the biotin-streptavidin interaction. The realtime data obtained on structural changes during the interactions is in excellent agreement with previously reported X-ray crystallography and neutron reflection data. The precision of the measurements taken was of the order of 0.01 nm with respect to protein size. The dual-parameter approach also allowed the stoichiometry of both of these interactions to be calculated, giving values that confirm the current understanding of the interactions. This approach provides detailed insights into the inherent and subtle link between structural change and function in proteins, to a degree not previously possible through mass change measurements alone. The technique is expected to find utility in the increasingly important study of protein structure and function.