Annales des Sciences Naturelles - Zoologie et Biologie Animale最新文献

The biometrical study of length, height and width of the successive vertebrae constituting the vertebral axis of the rainbow trout (Oncorhynchus mykiss) allows characteristic-looking vertebral profiles to be drawn. This study shows that the classical anatomical division of the vertebral column into two regions (truncal and caudal) is morphologically unrealistic; it is better represented by a zonation in three parts: a postcephalic region (or antero-truncal region) composed of 8 to 10 vertebrae the first two of which make a peculiar “couple”; a middle region integrating the following truncal vertebrae and the 18 to 20 first caudal ones; and finally a ural region (or postero-caudal region). This morphological zonation of the rachis is probably the functional result of the major role played by the vertebrae in transmitting the propulsive forces of the trunco-caudal muscles to the snout tip during the subcarangiform swimming in the rainbow trout.

We reevaluate a recent suggestion that the extra-embryonic membranes of the amniotic egg do not constitute an adaptation to reproduction on land, but rather appeared in an embryo-retaining ancestor, in which they facilitated interactions between the embryo and the mother. On the basis of a revised data set on the distribution of extended embryo retention in sarcopterygians, we suggest that stem-amniotes probably did not retain their eggs in utero for a great proportion of the embryonic development. Therefore, we tentatively reject the hypothesis that the initial function of the extra-embryonic membranes was to facilitate embryo-mother interactions. However, current controversies on amniote phylogeny render our conclusions tentative.

In a first approach to studying the effects of air pollutants, we describe some experimental results obtained after ingestion of polyaromatic hydrocarbons (HAP)^* by three species of locusts (Gomphocerus sibiricus, Gomphocerus rufus and Euchorthippus pulvinatus). We wanted to evaluate their toxicity, then to locate them in the organism. Two HAP, carcinogenic for mammals, were used. They are highly toxic for our locusts. Ingestion of 0.015 or 0.06 mg of 3 methylcholanthrene kills respectively 25 % and 50 % of them. Moreover, benzo-a-pyrene seems to have a greater toxicity, and E. pulvinatus is the most resistant species. Strongly fluorescent in UV light, 3 MC and BaP can be easily detected in the organism after dissection, and with more detail using frozen material. The microscope shows absorption activity of midgut; most of the organs are consequently invaded by intact hydrocarbon or its various derivatives. Muscles and reproductive organs show a bright fluorescence, which reaches its maximum in the nervous system. Tubes of Malpighi seem to be the principal route of elimination of these products. The remarkable susceptibility of some organs is encouraging for the progress of our study.

Sulfur concentration measurements in calcareous invertebrate hard-parts covering a wide range of taxa are compared, using relevant statistical tools, to mineralogical and microstructural features of skeletons. In parallel with recent data concerning sulfur characterization in mineralizing matrices, this allows the current concepts regarding early stages and further development of calcareous biominerals to be discussed.

An analysis of the growth patterns of two close relatives of the genus Accipiter (the European sparrowhawk A. nisus and the European goshawk A. gentilis) was conducted, in order to elucidate a possible mechanism for the evolution of the ontogeny of the goshawk from that of its presumed smaller ancestor. After allowing for isometric scaling, the ontogeny of the goshawk is shown to be clearly accelerated in relation to that of their presumed smaller ancestral relative.

The postembryonic development of the cartilaginous cephalic skeleton in Solea solea (Linné) was observed from hatching to the juvenile stage or postmetamorphic larva. Fry were trypsin-cleared and alcian-blue-stained. At hatching, Solea solea displays no cartilaginous structure. On day 3, the fry exhibit trabecular bars, Meckel's cartilages, palatoquadrates, hyosymplectics, hyoid bars, the first two ceratobranchials, and basibranchials 1–3. On day 4, ceratobranchials 3 and 4 form. On day 12, short taeniae marginales are formed on the well-developed otic capsules and the branchial basket is nearly complete. On day 14, a first cartilage reduction begins as the posterior part of the trabecula communis separates from the otic capsules. On day 18, metamorphosis begins. The tectum posterius completes posteriorly the braincase dome. On day 20, the left eye moves to the median crest of the head and the right eye shifts downwards slightly. Consequently, displacement of the right eye induces a deformation extending to the right pterygoid process. On day 23, both eyes are located on the same side. On day 29, cartilage reduction affects the hyosymplectics; it continues with the first two ceratobranchials on day 32 and with the otic capsules on day 40. On day 50, cartilage reduction has reached the lamina precerebralis. Only a few small lumps remain at the level of the neurocranium and the splanchnocranium.

Eight species of mesopsammic marine ciliates, collected on the mediterranean beaches of Sète or in the Thau pond, have been studied in order to specify their morphology and morphometry. Using new techniques of fixation and protargol impregnation acquired in recent years, the infraciliature of Karyorelictea ciliates of Trachelocercia sub. class were studied : Trachelolophos binucleatus nov. sp., Trachelolophos schulzei nov. comb., Trachelolophos setensis, Trachelolophos gigas, Tracheloraphis grisea, Tracheloraphis flexuosa, Tracheloraphis longicollis and Kovalevaia sulcata. For some of these species, several populations have been compared in order to know the intraspecific variation. A critical analysis attempts to establish the taxonomic value of the infraciliature structures and of the morphometric data. The problem of the morphogenesis and the feeding behaviour of theses ciliates have been called to mind.