Inhibition of NOminusb3 Uptake by Various Phloem-Translocated Amino Acids in Soybean Seedlings

We have examined the effect of different amino acids on NO     

Polydomy in ants: what we know, what we think we know, and what remains to be done

The correct identification of colony boundaries is an essential prerequisite for empirical studies of ant behaviour and evolution. Ant colonies function at various organizational levels, and these boundaries may be difficult to assess. Moreover, new complexity can be generated through the presence of spatially discrete subgroups within a more or less genetically homogeneous colony, a situation called polydomy. A colony is polydomous only if individuals (workers and brood) of its constituent nests function as a social and cooperative unit and are regularly interchanged among nests. This condition was previously called polycalic, and the term polydomy was used in a broader sense for a group of daughter nests of the same mother colony (implying limited female dispersal), without regard to whether these different nests continued to exchange individuals. We think that this distinction between ‘polycaly’ and ‘polydomy’ concerns two disparate concepts. We thus prefer the narrower definition of polydomy, which groups individuals that interact socially. Does this new level of organization affect the way in which natural selection acts on social traits? Here, after examining the history of terms, we review all ant species that have been described as expressing polydomous structures. We show that there is no particular syndrome of traits predictably associated with polydomy. We detail the existing theoretical predictions and empirical results on the ecology of polydomy, and the impact of polydomy on social evolution and investment strategies, while carefully distinguishing monogynous from polygynous species. Finally, we propose a methodology for future studies and offer ideas about what remains to be done. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 90 , 319–348.     

Various Aspects of the Biology of Agelena consociata Denis when Bred in the Laboratory

SYNOPSIS. Agelena consociata Denis, which Chauvin discoveredin Gabon, when put in a laboratory, weaves nests which are 2m² and consist of three different parts: shelters, a web, andvertical threads used as a snare. The snare stops insects intheir flight and causes them to fall into the web which thespiders use as their hunting field. These spiders have a nocturnalactivity which can be divided into two successive periods: afirst stage during which the spiders weave vertical threads,and a second stage of general activity. Hunting and eating are done in common. These activities andthe relations between the individuals which they involve, showin a definite way the social characteristics of these spiders. Eating favors an exchange of chemical substance between theindividuals, but we have not been able to determine the exactpart played by such an exchange. As study proceeds, we shall try to make clear the relationshipsbetween the individuals inside the society. We shall analyzegroup effects on physiology and behavior, comparing them tothose found for Agelena labyrinthica.     

COMPARISON OF THE EFFECT OF DIFFERENT SHORT CHAIN FATTY ACIDS ON THE GROWTH AND DIFFERENTIATION OF HUMAN COLONIC CARCINOMA CELL LINESIN VITRO

The aim of this study was to compare the effects of acetate, propionate, butyrate, iso-butyrate, valerate, iso-valerate and caproate on cell growth and on the activities of alkaline phosphatase (AP) and dipeptidyl aminopeptidase IV (DPP IV) by three human colonic adenocarcinoma cell lines. In addition to butyrate, propionate and valerate inhibited cell proliferation of the three cell lines. The other SCFAs did not influence cell proliferation. AP and DPP IV activities were strongly stimulated by butyrate on two of the three cell lines. On HT-29, AP was strongly stimulated, however DPPIV expression remained undetectable. Propionate and valerate exhibited a weaker stimulation, the other SCFAs being ineffective. The effect of SCFAs on cell proliferation and differentiation clearly depends on the number of carbons and on the configuration of the basic structure of the molecule.