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.     

Is Phillyrea angustifolia L. (Oleaceae) an androdioecious species?

LEPART, J. & DOMMEE B., 1992. Is Phillyrea angustifolia L. (Oleaceae) an androdioecious species? Observations during two or three years on three natural populations of Phillyrea angustifolia growing in contrasting environments in southern France show that two distinct phenotypes occur in approximately equal proportions: hermaphrodites, which produce pollen and seeds, and males, which produce pollen only. The populations studied are thus morphologically androdioecious. Biometric investigation of the two morphs shows that they are clearly distinguished by (1) the shape of the stigma and (2) the ovary which is well developed in hermaphrodites and aborted in males. Neither size of anthers and corolla, nor pollen germination, differ between the two sexes. In the Camargue, where P. angustifolia is presently an invader, controlled crosses between hermaphrodites (selfing and inter-individual) are partially successful. In contrast, such crosses are sterile in the well-established population of the La Gardiole. Hence the Camargue population appears to be functionally androdioecious and La Gardiole functionally dioecious. This breeding system is particularly puzzling, since the occurrence of anemogamy and possible selfing do not fit classical explanations of androdioecy. The ability of hermaphrodites to be functionally male and female could be particularly adaptive in founding populations. Since functional hermaphroditism occurs in expanding populations of the Camargue population, we consider that the androdioecy of P. angustifolia could be a kind of leaky dioecism.     

Sex-specific transgenerational effects of early developmental conditions in a passerine

Most studies dealing with the trade-off between offspring number and quality have overlooked the long-term consequences for the progeny. High investment in offspring number usually results in an increased competition among nest mates. The deterioration of the early developmental conditions, due to this increased competition, can impair individual quality over the long term, and subsequently affect survival and lifetime fecundity. Moreover, the consequences of the allocation rule to offspring number vs. quality can extend across generations and give raise to grandparental effects. These transgenerational trade-offs have been explored rarely. In the present study, we manipulated the breeding effort of captive zebra finches ( Taeniopygia guttata ) by offering them enlarged or reduced broods. Offspring reared under these conditions were allowed to breed freely in an outdoor aviary, during their entire lifespan. Second-generation fledglings whose mother was raised in enlarged broods were in lower body condition than offspring whose mother was raised in reduced broods. However, second-generation fledglings were not affected by the brood size experienced by the father. These results show that the solution of parental dilemma, whether producing a small number of high quality offspring or a large number of poor quality descendants, must take into account the long-term transgenerational effects acting on grandchildren.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 91 , 469–474.