Thyroid hormone receptors are required for the melatonin-dependent control of Rfrp gene expression in mice.

Mammals adapt to seasons using a neuroendocrine calendar defined by the photoperiodic change in the nighttime melatonin production. Under short photoperiod, melatonin inhibits the pars tuberalis production of TSHβ, which, in turn, acts on tanycytes to regulate the deiodinase 2/3 balance resulting in a finely tuned seasonal control of the intra-hypothalamic thyroid hormone T3. Despite the pivotal role of this T3 signaling for synchronizing reproduction with the seasons, T3 cellular targets remain unknown. One candidate is a population of hypothalamic neurons expressing Rfrp, the gene encoding the RFRP-3 peptide, thought to be integral for modulating rodent's seasonal reproduction. Here we show that nighttime melatonin supplementation in the drinking water of melatonin-deficient C57BL/6J mice mimics photoperiodic variations in the expression of the genes Tshb, Dio2, Dio3, and Rfrp, as observed in melatonin-proficient mammals. Notably, we report that this melatonin regulation of Rfrp expression is no longer observed in mice carrying a global mutation of the T3 receptor, TRα, but is conserved in mice with a selective neuronal mutation of TRα. In line with this observation, we find that TRα is widely expressed in the tanycytes. Altogether, our data demonstrate that the melatonin-driven T3 signal regulates RFRP-3 neurons through non-neuronal, possibly tanycytic, TRα.journal article2020 Aug 102020 08 10importe

DeepIso - A global open database of stable isotope ratios and elemental contents for deep-sea ecosystems.

Stable isotopes have been instrumental to many key-findings about deep-sea ecosystem functioning, particularly in chemosynthesis-based habitats (hydrothermal vents, cold seeps). However, constraining sampling logistics commonly limit the scope, extent, and therefore insights drawn from isotope-based deep-sea studies. Overall, much is left to discover about factors globally influencing food web structure in deep-sea ecosystems. In this context, it is crucial that all generated data are easily discoverable, available and reusable. DeepIso is a collaborative effort to produce a global compilation of stable isotope ratios and elemental contents in organisms from deep-sea ecosystems. In doing so, it aims to provide the deep-sea community with an open data analysis tool that can be used in the context of future ecological research, and to help deep-sea researchers to use stable isotope markers at their full efficiency. The database, accessible under CC-BY licence at https://doi.org/10.17882/76595, currently contains 18677 fully documented measurements. Archived parameters include δ13C (n = 4587), δ15N (n = 4388), δ34S (n = 951), %C (n = 2740), %N (n = 2741), %S (n = 752) and C/N ratio (n = 2518). Those measurements pertain to 4378 distinct samples belonging to 493 taxa, plus sediments, suspended particulate organic matter, plankton and detritus. Samples were taken between 1989 and 2018 in multiple environments (hydrothermal vents, cold seeps, cold water coral reefs, and other benthic or pelagic environments) and at depths ranging up to 5209 meters. To maximise the scope of the project, we are looking to integrate more data, either underlying published articles, from grey literature, or even unpublished. We’ll be happy to assist in data formatting and publication. If you are willing to contribute, or simply if you have feedback about the database, please get in touch via [email protected]

Building up DeepIso - A global open database of stable isotope ratios and elemental contents for deep-sea ecosystems.

Stable isotopes have been instrumental to many key-findings about deep-sea ecosystem functioning, particularly in chemosynthesis-based habitats (hydrothermal vents, cold seeps). However, constraining sampling logistics commonly limit the scope, extent, and therefore insights drawn from isotope-based deep-sea studies. Overall, much is left to discover about factors globally influencing food web structure in deep-sea ecosystems. In this context, it is crucial that all generated data are easily discoverable, available, and reusable. DeepIso is a collaborative effort to produce a global compilation of stable isotope ratios and elemental contents in organisms from deep-sea ecosystems. In doing so, it aims to provide the deep-sea community with an open data analysis tool that can be used in the context of future ecological research, and to help deep-sea researchers to use stable isotope markers at their full efficiency. The database, accessible under CC-BY licence at https://doi.org/10.17882/76595, currently contains 18677 fully documented measurements. Archived parameters include δ13C (n = 4587), δ15N (n = 4388), δ34S (n = 951), %C (n = 2740), %N (n = 2741), %S (n = 752) and C/N ratio (n = 2518). Those measurements pertain to 4378 distinct samples belonging to 493 taxa, plus sediments, suspended particulate organic matter, plankton and detritus. Samples were taken between 1989 and 2018 in multiple environments (hydrothermal vents, cold seeps, cold water coral reefs, and other benthic or pelagic environments) and at depths ranging up to 5209 meters. To maximise the scope of the project, we are looking to integrate more data, either underlying published articles, from grey literature, or even unpublished. We’ll be happy to assist in data formatting and publication. If you are willing to contribute, or simply if you have feedback about the database, please get in touch via [email protected]

Thyroid hormone receptor alpha modulates fibrogenesis in hepatic stellate cells

Objective: Progressive hepatic fibrosis can be considered the final stage of chronic liver disease. Hepatic stellate cells (HSC) play a central role in liver fibrogenesis. Thyroid hormones (TH, e.g. thyroxine; T4 and triiodothyronine; T3) significantly affect development, growth, cell differentiation and metabolism through activation of TH receptor α and/or β (TRα/β). Here, we evaluated the influence of TH in hepatic fibrogenesis. Design: Human liver tissue was obtained from explanted livers following transplantation. TRα-deficient (TRα-KO) and wild-type (WT) mice were fed a control or a profibrogenic methionine-choline deficient (MCD) diet. Liver tissue was assessed by qRT-PCR for fibrogenic gene expression. In vitro, HSC were treated with TGFβ in the presence or absence of T3. HSC with stable TRα knockdown and TRα deficient mouse embryonic fibroblasts (MEF) were used to determine receptor-specific function. Activation of HSC and MEF was assessed using the wound healing assay, Western blotting, and qRT-PCR. Results: TRα and TRβ expression is downregulated in the liver during hepatic fibrogenesis in humans and mice. TRα represents the dominant isoform in HSC. In vitro, T3 blunted TGFβ-induced expression of fibrogenic genes in HSC and abrogated wound healing by modulating TGFβ signalling, which depended on TRα presence. In vivo, TRα-KO enhanced MCD diet-induced liver fibrogenesis. Conclusion: These observations indicate that TH action in non-parenchymal cells is highly relevant. The interaction of TRα with TH regulates the phenotype of HSC via the TGFβ signalling pathway. Thus, the TH–TR axis may be a valuable target for future therapy of liver fibrosis.</p

Increased sensitivity to thyroid hormone in mice with complete deficiency of thyroid hormone receptor alpha.

International audienc

Recurrent domestication by Lepidoptera of genes from their parasites mediated by Bracoviruses

This study received financial support from the Spanish Ministry for Science and Technology (AGL2011-30352-C02-02 and AGL2014-57752-C02-2R) and in France recurrent funding from CNRS and University Francois Rabelais (Tours).Bracoviruses are symbiotic viruses associated with tens of thousands of species of parasitic wasps that develop within the body of lepidopteran hosts and that collectively parasitize caterpillars of virtually every lepidopteran species. Viral particles are produced in the wasp ovaries and injected into host larvae with the wasp eggs. Once in the host body, the viral DNA circles enclosed in the particles integrate into lepidopteran host cell DNA. Here we show that bracovirus DNA sequences have been inserted repeatedly into lepidopteran genomes, indicating this viral DNA can also enter germline cells. The original mode of Horizontal Gene Transfer (HGT) unveiled here is based on the integrative properties of an endogenous virus that has evolved as a gene transfer agent within parasitic wasp genomes for approximate to 100 million years. Among the bracovirus genes thus transferred, a phylogenetic analysis indicated that those encoding C-type-lectins most likely originated from the wasp gene set, showing that a bracovirus-mediated gene flux exists between the 2 insect orders Hymenoptera and Lepidoptera. Furthermore, the acquisition of bracovirus sequences that can be expressed by Lepidoptera has resulted in the domestication of several genes that could result in adaptive advantages for the host. Indeed, functional analyses suggest that two of the acquired genes could have a protective role against a common pathogen in the field, baculovirus. From these results, we hypothesize that bracovirus-mediated HGT has played an important role in the evolutionary arms race between Lepidoptera and their pathogens

Phylogeography of the Guinea multimammate mouse (Mastomys erythroleucus) : a case study for Sahelian species in West Africa

Aim To investigate the phylogeographical structure of the Guinea multimammate mouse, Mastomys erythroleucus (Temminck, 1853), a widespread murid rodent in sub-Saharan (Sahel and Sudan) savannas, for a better understanding of the impacts of geographical and historical factors on the evolutionary history of this species, in the context of the growing database of phylogeographical studies of African savanna mammal species. Location Sahel and Sudan savannas, Africa. Methods We sequenced the whole cytochrome b gene in 211 individuals from 59 localities distributed from Senegal to Ethiopia. Sequence data were analysed using both phylogenetic (several rooted tree-construction methods, median-joining networks) and population genetic methods (spatial analyses of molecular variance, mismatch distributions). Results Haplotypes were distributed into four major monophyletic groups corresponding to distinct geographical regions across a west-east axis. Diversification events were estimated to have occurred between 1.16 and 0.18 Ma. Main conclusions Vicariance events related to the fragmentation of savanna habitats during the Pleistocene era may explain the phylogeographical patterns observed. Genetic structure was consistent with a role of major Sahelian rivers as significant barriers to west-east dispersal. Recent demographic expansions probably occurred during arid phases of the Holocene with the southward expansion of savannas

Cellular localization of BV2-5 and its effect on actin distribution.

<p>Sf21 cells were infected with different recombinant viruses. The upper horizontal panel represents non-infected cells and the rest represent cells infected with AcMNPV-GFP, AcMNPV-BV2-5GFP and AcMNPV-GFP treated by latrunculin A, respectively. The fluorescence was visualized by confocal microscopy. Nuclei are visualized by DAPI and actin is visualized by phalloidin-TRITC staining.</p

Measure of selection operating on <i>Ben4</i> and <i>Ben9</i> genes in <i>D</i>. <i>plexippus</i> and 4 related species.

<p>a) Phylogenetic tree based on the nucleotide sequence alignment of the region shared between <i>Ben4</i> and <i>Ben9</i> in <i>Danaus</i> species samples and CcBV. The values in brackets indicate the number of lepidopteran individuals used in the analysis. b) Plot of the dN/dS value of each codon along the <i>Ben</i> genes based on the alignment of the butterfly sequences. The red bars represent values that are significantly under positive or negative selection (HyPhy, p-value ≤ 0.1). The asterisks identify the sites also under positive selection with the PAML approach. The yellow blocks under the dN/dS graphs represent the <i>Ben</i> gene structure composed of three exons. The first exon corresponds to a PHA02737 domain and the BEN domain (represented in purple) is encoded by the end of the third exon. Note that the truncated <i>Ben4</i> gene conserved in <i>D</i>. <i>plexippus</i> corresponds to the third exon of CcBV <i>Ben4</i> gene, which contains the BEN domain.</p

Analysis of BEN 9 encoding insertions in the <i>Danaina</i> subtribe.

<p>A) Analysis of BEN9 encoding insertions in genomic DNA of individuals from different species of the <i>Danaina</i> subtribe by <i>ben9</i> gene PCR amplification from Lepidoptera of the species <i>Danaus chrysippus chrysippus</i> (Oman), <i>Danaus genutia</i> (Thailand), <i>Danaus plexippus</i> (Q, caterpillar sampled in Québec, A, adults from Australia), <i>Tirumala septentrionis septentrionis</i> (Malaysia). C1, C2, C3: control PCR (without DNA) performed with primer pairs used respectively for <i>D</i>. <i>plexippus</i>, <i>D</i>. <i>chrysippus</i>/<i>D</i>. <i>genutia</i> and <i>T</i>. <i>septentrionis</i> PCRs B) RT-PCR analysis of <i>Ben9</i> expression in <i>D</i>. <i>plexippus</i> caterpillars from Québec. <i>Ben9</i> expression was detected in three individuals. No PCR amplification of <i>Ben9</i> was observed on RNA samples that were not subjected to RT (No RT). C) PCR fragments obtained from <i>D</i>. <i>plexippus</i> genomic DNA and cDNA and schematic represention of <i>Ben9</i> gene and <i>D</i>. <i>plexippus Ben9</i> cDNA organization. The black bar indicates that exon 3 is not to scale. Note that in the amplified fragment corresponding to <i>D</i>. <i>plexippus</i> cDNA, the two <i>Ben9</i> intron sequences have been excised as observed in <i>Ben9</i> cDNA obtained from <i>Manduca sexta</i> parasitized by <i>Cotesia congregata</i> [<a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1005470#pgen.1005470.ref033" target="_blank">33</a>]. The phylogenetic tree is adapted from [<a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1005470#pgen.1005470.ref034" target="_blank">34</a>]. Dating of the common ancestor is reported from [<a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1005470#pgen.1005470.ref035" target="_blank">35</a>].</p