Biomedical subjects

Yves Desdevises

Publications and source records attributed to Yves Desdevises.

5 recordsLinked to original sources

PubMed2006

Retinal, pineal and diencephalic expression of frog arylalkylamine N-acetyltransferase-1.

The arylalkylamine N-acetyltransferase (AANAT) is a key enzyme in the rhythmic production of melatonin. Two Aanats are expressed in Teleost fish (Aanat1 in the retina and Aanat2 in the pineal organ) but only Aanat1 is found in tetrapods. This study reports the cloning of Aanat1 from R. perezi. Transcripts were mainly expressed in the retina, diencephalon, intestine and testis. In the retina and pineal organ, Aanat1 expression was in the photoreceptor cells. Expression was also seen in ependymal cells of the 3rd ventricle and discrete cells of the suprachiasmatic area. The expression of Aanat1 in both the retina and pineal organ, and the absence of Aanat2 suggests that green frog resembles more to birds and mammals than to Teleost fish, as far as Aanat is concerned. The significance of Aanat1 in extra-pineal and extra-retinal tissues remains to be elucidated; in the diencephalon, it might be associated to the so-called deep brain photoreceptor cells.

Amino Acid Sequence↗

PubMed2003

Quantifying phylogenetically structured environmental variation.

Comparative analysis methods control for the variation linked to phylogeny before attempting to correlate the remaining variation of a trait to present-day conditions (i.e., ecology and/or environment). A portion of the phylogenetic variation of the trait may be related to ecology, however; this portion is called "phylogenetic niche conservatism." We propose a method of variation partitioning that allows users to quantify this portion of the variation, called the "phylogenetically structured environmental variation." The new method is applied to published data to study, in a phylogenetic framework, the link between body mass and population density in 79 species of mammals. The results suggest that an important part of the variation of mammal body mass is related to the common influence of phylogeny and population density.

Analysis of Variance↗

PubMed2002

Investigating patterns may reveal processes: evolutionary ecology of ectoparasitic monogeneans.

We reviewed several published and ongoing studies concerning monogenean communities. Patterns of species richness, host specificity, community structure and host--parasite coevolutionary interaction were carefully analysed, and hypotheses of evolutionary processes are proposed. The structuring of monogenean communities seems to be related to both ecological and historical constraints. The database supports an absence of intra- and interspecific competition in monogeneans. Species richness seems to be more due to host characteristics than to parasite interactions. Monogeneans seem to specialise on large hosts, leading to greater species richness on those hosts. The morphometric evolution of attachment and copulatory organs support the hypothesis of a reproductive segregation among conspecifics parasitising the same host(s). It also suggests the existence of concurrent adaptive and non-adaptive processes. The general absence of a coevolutionary pattern between host and parasites also suggests the constraints of history without dismissing the influences of ecological factors in the structuring of the communities. More generally, we strengthen the need to study the structure of communities in a phylogenetic context.

Animals↗

PubMed2002

A statistical test for host-parasite coevolution.

A new method, ParaFit, has been developed to test the significance of a global hypothesis of coevolution between parasites and their hosts. Individual host-parasite association links can also be tested. The test statistics are functions of the host and parasite phylogenetic trees and of the set of host-parasite association links. Numerical simulations are used to show that the method has correct rate of type I error and good power except under extreme error conditions. An application to real data (pocket gophers and chewing lice) is presented.

Animals↗

PubMed2002

Coevolution between Lamellodiscus (Monogenea: Diplectanidae) and Sparidae (Teleostei): the study of a complex host-parasite system.

Host-parasite coevolution was studied between Sparidae (Teleostei) fishes and their parasites of the genus Lamellodiscus (Monogenea, Diplectanidae) in the northwestern Mediterranean Sea. Molecular phylogenies were reconstructed for both groups. The phylogenctic tree of the Sparidae was obtained from previously published 16S mitochondrial DNA (mtDNA) sequences associated with new cytochrome-b mtDNA sequences via a "total evidence" procedure. The phylogeny of Lamellodiscus species was reconstructed from 18S rDNA sequences that we obtained. Host-parasite coevolution was studied through different methods: TreeFitter, TreeMap, and a new method, ParaFit. If the cost of a host switch is not assumed to be high for parasites, all methods agree on the absence of widespread cospeciation processes in this host-parasite system. Host-parasite associations were interpreted to be due more to ecological factors than to coevolutionary processes. Host specificity appeared not to be related to host-parasite cospeciation.

Animals↗