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Bertrand S.,CNRS Integrative Biology of Marine Organisms | Iwema T.,University of Reunion Island | Escriva H.,CNRS Integrative Biology of Marine Organisms
Molecular Biology and Evolution | Year: 2014

Complex metazoan bodies require cell-to-cell communication for development, a process often mediated by signaling molecules binding to specific receptors. Relatively few signaling pathways have been recruited during evolution to build multicellular animals from unicellular zygotes. Of these few signaling pathways, one of particular importance is the receptor tyrosine kinase (RTK) pathway. In metazoans, fibroblast growth factors (FGFs) bind to receptors in the RTK family, but the origin of the FGF gene family has so far remained a mystery. Here we show that extant bona fide FGFs most likely originated from proteins bearing an FGF-like domain that arose in a choanoflagellate/metazoan ancestor. We found orthologous genes closely related to FGF in choanoflagellates as well as in many metazoans such as sponges, acoels, protostomes, or nonvertebrate deuterostomes. We also show that these genes have a common evolutionary history with Retinitis Pigmentosa 1 (RP1). Even if some metazoan signaling pathways emerged long before multicellularity, we show that FGFs, like their receptors, originated in a eumetazoan ancestor. © 2013 The Author.

Mendlova M.,Masaryk University | Desdevises Y.,CNRS Integrative Biology of Marine Organisms | Civanova K.,Masaryk University | Pariselle A.,Montpellier University | Simkova A.,Masaryk University
PLoS ONE | Year: 2012

The goals of this paper were to investigate phylogenetic and evolutionary patterns of cichlid fish from West Africa and their Cichlidogyrus and Scutogyrus monogenean parasites, to uncover the presence of host-parasite cospeciation and to assess the level of morphological adaptation in parasites. This required the following steps, each one representing specific objectives of this paper: (1) to build phylogenetic trees for Cichlidogyrus and Scutogyrus species based on ribosomal DNA sequences, (2) to investigate phylogenetic relationships within West African cichlid fish based on the analysis of mitochondrial cytochrome b DNA sequences, (3) to investigate host-parasite cophylogenetic history to gain clues on parasite speciation process, and (4) to investigate the link between the morphology of the attachment apparatus and parasite phylogeny. Phylogenetic analyses supported the monophyletic origin of the Cichlidogyrus/Scutogyrus group, and suggested that Cichlidogyrus is polyphyletic and that Scutogyrus is monophyletic. The phylogeny of Cichlidae supported the separation of mouthbrooders and substrate-brooders and is consistent with the hypothesis that the mouthbrooding behavior of Oreochromis and Sarotherodon evolved from substrate-brooding behavior. The mapping of morphological characters of the haptor onto the parasite phylogenetic tree suggests that the attachment organ has evolved from a very simple form to a more complex one. The cophylogenetic analyses indicated a significant fit between trees using distance-based tests, but no significant cospeciation signal using tree-based tests, suggesting the presence of parasite duplications and host switches on related host species. This shed some light on the diversification process of Cichlidogyrus species parasitizing West African cichlids. © 2012 Mendlova et al.

Sarabeev V.,Zaporizhzhia National University | Desdevises Y.,CNRS Integrative Biology of Marine Organisms
Parasitology International | Year: 2014

Within ectoparasitic fish monogeneans, the genus Ligophorus contains a high number of species from which several were recently described. The precise determination of their taxonomic status requires robust diagnostic morphologic features that rely predominantly on a restricted set of sclerotized structures. In the present study, these morphological characters were used for the reconstruction of a phylogenetic tree, which was compared with a tree built from molecular data (28S and ITS1 DNA sequences). Thirty-eight morphological characters were used in 29 species of Ligophorus from the Atlantic and Pacific regions and 5 species within close genera of Dactylogyridae. The morphological and molecular phylogenetic trees are congruent and suggest that the genus Ligophorus is monophyletic, and that species parasitizing Liza spp. and Chelon labrosus occupy basal positions. The present study suggests that host switching is a common event in this host-parasite association, because about half of the species infecting the same host species are not close relatives. Following host switching, dispersal with vicariance is probably an important force shaping the present distribution and diversity of Ligophorus. The pattern of occurrence of Ligophorus spp. on Mugil cephalus supports that reproductive isolation and therefore parallel speciation are taking place among these parasitic organisms. © 2013 Elsevier Ireland Ltd.

James J.E.,University of Sussex | Piganeau G.,CNRS Integrative Biology of Marine Organisms | Eyre-Walker A.,University of Sussex
Molecular Ecology | Year: 2016

We have investigated whether there is adaptive evolution in mitochondrial DNA, using an extensive data set containing over 500 animal species from a wide range of taxonomic groups. We apply a variety of McDonald-Kreitman style methods to the data. We find that the evolution of mitochondrial DNA is dominated by slightly deleterious mutations, a finding which is supported by a number of previous studies. However, when we control for the presence of deleterious mutations using a new method, we find that mitochondria undergo a significant amount of adaptive evolution, with an estimated 26% (95% confidence intervals: 5.7-45%) of nonsynonymous substitutions fixed by adaptive evolution. We further find some weak evidence that the rate of adaptive evolution is correlated to synonymous diversity. We interpret this as evidence that at least some adaptive evolution is limited by the supply of mutations. © 2015 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd.

Roure A.,CNRS Integrative Biology of Marine Organisms | Darras S.,CNRS Integrative Biology of Marine Organisms
Developmental Biology | Year: 2015

The tail ascidian larval peripheral nervous system is made up of epidermal sensory neurons distributed more or less regularly in ventral and dorsal midlines. Their formation occurs in two-steps: the ventral and dorsal midlines are induced as neurogenic territories by Fgf9/16/20 and Admp respectively. The Delta2/Notch interaction then controls the number of neurons that form. The genetic machinery acting between the inductive processes taking place before gastrulation and neuron specification at tailbud stages are largely unknown. The analysis of seven transcription factors expressed in the forming midlines revealed an unexpected complexity and dynamic of gene expression. Their systematic overexpression confirmed that these genes do not interact following a linear cascade of activation. However, the integration of our data revealed the distinct key roles of the two upstream factors Msxb and Nkx-C that are the earliest expressed genes and the only ones able to induce neurogenic midline and ESN formation. Our data suggest that Msxb would be the primary midline gene integrating inputs from the ventral and dorsal inducers and launching a pan-midline transcriptional program. Nkx-C would be involved in tail tip specification, in maintenance of the pan-midline network and in a posterior to anterior wave controlling differentiation. © 2015.

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