Biomedical subjects
J Bouvet
Publications and source records attributed to J Bouvet.
Unusual mitochondrial DNA polymorphism in two local populations of blue tit Parus caeruleus.
Mitochondrial DNA (mtDNA) from 25 blue tits Parus caeruleus sampled from two populations of the Grenoble region (France) was assayed for polymorphism with 17 restriction endonucleases. Nine genotypes were found. Several mtDNA genotypes were also analysed by amplification via the polymerase chain reaction (PCR) and direct sequencing of 903 bp of the cytochrome b gene. The mtDNA polymorphism is greater in P. caeruleus than in other comparable bird species and results from the presence of two clearly differentiated mitochondrial lineages. Using the data of restriction polymorphism, the mean sequence divergence between individuals of the two lineages is 1.23%. Therefore, P. caeruleus should fall into the category II of phylogeographic pattern sensu Avise et al. (1987): discontinuous mtDNA genotypes which co-occur in the same region. P. caeruleus, like humans and other mobile species with high gene flow, seems to have lost its geographic structure in terms of mtDNA phylogeny. This unusual mitochondrial polymorphism can be explained by the recent admixture of two long-term isolated populations. This could be accounted for by two different scenarios. One assumes a simultaneous post-glacial colonization of the Grenoble region by two isolated European populations of P. caeruleus. Alternatively, hybridization between P. caeruleus and P. cyanus could have caused the observed pattern of mtDNA variation.
Universal primers for amplification of three non-coding regions of chloroplast DNA.
Six primers for the amplification of three non-coding regions of chloroplast DNA via the polymerase chain reaction (PCR) have been designed. In order to find out whether these primers were universal, we used them in an attempt to amplify DNA from various plant species. The primers worked for most species tested including algae, bryophytes, pteridophytes, gymnosperms and angiosperms. The fact that they amplify chloroplast DNA non-coding regions over a wide taxonomic range means that these primers may be used to study the population biology (in supplying markers) and evolution (inter- and probably intraspecific phylogenies) of plants.
Morphometric analysis of the cerebellar Purkinje cell in the developing normal and hypothyroid chick.
A morphometric analysis of Purkinje cells in the developing cerebellar cortex of the chick was performed in normal animals and embryos made hypothyroid by one or two spaced injections of tetramethylthiourea. Profiles of 162 Purkinje cells, from Golgi-Cox treated sections were analysed. Soma area, perimeter and circularity index, cumulative length of the dendrites and number of dendritic bifurcations were studied. The results showed significant differences between control and hypothyroid animals. There were no important differences between birds rendered transiently hypothyroid with a single injection and those made chronically hypothyroid with dual injections. This confirms that the Purkinje cell is very dependent on thyroid hormone especially during the early phases of its morphogenesis. The development of the Purkinje cell was the most affected process of cerebellar cortex maturation in the thyroid-deficient chick. The dendritic arborization was particularly hypoplastic. Moreover, a dynamic balance appeared to exist between the development of the dendritic arborization and that of the perikaryon.
Enveloping layer and periderm of the trout embryo (Salmo trutta fario L.)20U.
The origin of pericarderm and epidermis has been studied in trout embryos from stage 20(2 days after fertilization at 10degrees c) to hatching (stage 410). Between stages 20 and 50, the blastodisc consists of an inner mass of blastomeres covered by a superficial layer of closely packed blastomeres, the peripheral layer. This layer gives rise to both peripheral cells and to cells joining the inner mass of blastomeres. Between stages 50 and 110, junctions differentiate between peripheral cells. This newly formed superficial epithelium the enveloping layer, no longer gives rise to inward migrating cells. From stage 110 on, a basement membrane differentiates beneath a one-cell thick subperipheral layer, which thus becomes the ectodermal basal layer, the prospective epidermal basal layer. From these and ultrastructural observations, it is concluded that 1)the epidermis apparently originates, at least in part from the peripheral cells, between stages 20 and 50; 2) the periderm assumes a protective function over the body of the embryo and also a secretory function over the yolk sac (probably producing the hatching enzymes); 3)the periderm, which is a temporary structure, appears to play the role of an embryonic membrane in teleosts.