Éditeur(s) : Université des Antilles AREBio Groupe de recherche BIOSPHERES : BIOlogie, Sciences Physiques & Humaines pour les énergies Renouvelables, l
Extrait de : 1er colloque international BIOSPHERES, du 18 au 20 juin 2019. Université des Antilles
Description : Drosophila often offers many advantages as an experimental organism. The dead ringer (dri) gene of drosophila melanogaster is a member of the recently discovered ARID-box family of eukaryotic genes that encodes proteins with a conserved DNA-binding domain. dri itself is highly well conserved with specific orthologs from human to yeast genomes. This family include ARID3A, 3B and 3C with have role in embryonic pattening, cell lineage gene regulation, cell cycle control, transcriptional regulation and chromatin structure modification. We first showed that the gene encoding ARID3A also known as Bright (B cell regulator of immunoglobulin heavy chain transcription) play critical roles in B-cell development and SATB1 in T-cell transcription regulation. In this international workshops we will expose a comprehensive understanding of these molecules and better knowledge of their specific targets and function-interactions in controlling cell fate decisions and development. In addition, dri have homology with the Aedes aegypti mosquitoes which had ability to carry and spread disease to human. More than half of the world?s population live in areas where this mosquito species is present, including Martinique. Sustained mosquito control efforts are important to prevent outbreaks from Dengue, Chikungunya, malaria, zika diseases. Discovering the functions of AT-rich genes in preventing illness from mosquito is the central goal for raising working progress hypothesis.

Droits : CC-BY-NC-ND - Attribution - Pas d'utilisation commerciale - Pas de modification
Permalien : http://www.manioc.org/fichiers/V19077
V19077

Éditeur(s) : HAL CCSD American Physiological Society
Résumé : Full text: http://jn.physiology.org/content/88/3/1475
International audience
The contribution of voltage-gated calcium channels (VGCC) to the development of cultured embryonic cockroach brain neurons was assessed using pharmacological agents. VGCC currents were recorded using the patch-clamp technique and were found to be blocked dose-dependently by micromolar concentrations of mibefradil. The activation and inactivation properties of the calcium channels enable a sizeable calcium current to flow at rest (about -30 and -20 mV in high-potassium culture media). As expected, the cytoplasmic-free calcium concentration was found to rise when the extracellular potassium concentration was raised from 3 to 15 and 30 mM. The effects of VGCC blockers and calcium chelators were different in fresh and in mature cultures in which the neurons were connected to each other to form a defined network. In fresh cultures, the two non-selective VGCC blockers (verapamil and mibefradil) induced a dose-dependent cell death that was proportional to their blocking effect on I(Ba). This effect could not be prevented by addition of fetal calf serum to the culture medium. A similar effect was obtained using intra- or extracellular calcium chelating agents (10 microM BAPTA-AM or 10 mM EGTA). Quite unexpectedly, blockade of the P/Q-like (omega-Aga WA-sensitive) component of the calcium current by 500 nM of omega-AgaTx IVA had no lethal effect, suggesting that the corresponding channels are not involved in the survival mechanism. As expected from their lack of effect on I(Ba), isradipine, nifedipine, and omega-CgTx GVIA did not induce cell death. When the neurons started growing neurites, their sensitivity to calcium channel blockade by mibefradil decreased, indicating a correlation between neurite outgrowth and resistance to calcium depletion. In mature cultures, the neurons became resistant to mibefradil, verapamil, and BAPTA-AM. However, these agents, as well as omega-AgaTx IVA, had a significant inhibitory effect on the increase in diameter of the connectives that linked adjacent clusters of neurons. This effect has been shown to result, in the case of mibefradil, from an inhibition of neurite outgrowth characterized by a significant reduction of the number of primary neurites and secondary branchings but not to a significant modification of the diameter of individual neurites. These results support the view that, as in vertebrates, calcium influx through VGCC plays an important role in survival and neurite outgrowth of cultured embryonic insect neurons. The differential contribution of the P/Q-like and R-like (omega-Aga WA-sensitive) calcium channels in these processes is discussed.
ISSN: 0022-3077

hal-00982287
https://hal.archives-ouvertes.fr/hal-00982287
DOI : 10.1152/jn.00749.2001
PUBMED : 12205168

Éditeur(s) : HAL CCSD Nature Publishing Group
Résumé : International audience
The widely-used herbicide atrazine (ATZ) is detected in ground and surface water in many countries. Several studies in animals have demonstrated that ATZ has endocrine-disrupting effects on male and female reproduction in many vertebrate species. In this study, we investigated the effects of ATZ exposure on meiosis, a key step in gametogenesis in mammals. The treatment was initiated before oocyte entry into meiosis, which occurs during the embryonic period in females. We found that embryonic exposure to ATZ increases the level of 8-oxo-guanine in the nucleus of meiotic cells, reflecting oxidative stress and affecting meiotic double-strand break repair, chromosome synapsis and crossover numbers. Finally, embryonic exposure to ATZ reduces the number of primordial follicles and increases the incidence of multi-oocyte follicles in adult mice. Our data demonstrate that embryonic exposure to ATZ disrupts prophase I of meiosis and affects normal follicle formation in female mice.
ISSN: 2045-2322

hal-01560149
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01560149
DOI : 10.1038/s41598-017-03738-1
PUBMED : 28615648

Éditeur(s) : HAL CCSD Elsevier Masson
Résumé : International audience
The premature loss of ovarian function may have physical and psychological consequences. A better understanding of its mechanism is therefore needed. Because they are affecting the oocyte quality, the decline of the ovarian reserve and high maternal age are implicated in many defects leading to chromosomal defects, modifications of gene expression or alterations of the mitochondrial pattern of the oocyte. However, cellular therapies such as ovarian follicle activation or isolation of ovarian stem cells are promising treatments of ovarian failure
Le diagnostic d’insuffisance ovarienne chez une femme ayant un projet d’enfanter aura des conséquences non seulement physiques mais également psychologiques. L’optimisation des stratégies de prise en charge thérapeutique nécessite une meilleure compréhension des mécanismes de survenue de cette défaillance. Les mécanismes responsables de la constitution et du maintien de la réserve ovarienne commencent à être élucidés. Avec le déclin de la réserve ovarienne, la qualité ovocytaire diminue, accentuant la baisse de la fertilité associée à l’âge maternel. Les ovocytes et les embryons résultant de patientes âgées présentent des taux d’aneuploïdies élevés, liés à des défauts de cohésion chromosomique et d’instabilité du fuseau méiotique, diminution de la capacité de réparation de l’ADN, altération de l’expression des gènes ou à une altération du fonctionnement mitochondrial. Avec la possibilité d’activer in vitro la folliculogenèse et l’isolement de cellules souches ovariennes, plusieurs pistes de thérapie cellulaire commencent à se développer et semblent très prometteuses.
ISSN: 1297-9589

hal-01231432
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01231432
DOI : 10.1016/j.gyobfe.2015.10.008
PUBMED : 26597936

Éditeur(s) : HAL CCSD Elsevier Masson
Résumé : National audience
Sperm and embryos cryopreservation is a commonly applied technique for several years. Recently authorized in France, vitrification tends to replace gradually the conventional technique of slow freezing, so upsetting the practices in the management of patients. It allows from now on the cryopreservation of oocytes and opens new perspectives in egg donation either still in fertility preservation. This review thus attempted to examine the contribution of vitrification in the freezing of oocytes and human embryos at various stages of development. If obviously vitrification appears as the current method of choice for the cryopreservation of oocytes as well as blastocysts, the results are less cut as regards embryos to early stages. No increase in adverse obstetric and perinatal outcomes in children conceived from vitrified oocytes or embryos is noted in the literature
ISSN: 0368-2315

hal-01282445
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01282445
DOI : 10.1016/j.jgyn.2015.02.015
PUBMED : 25869444

Éditeur(s) : Université de la Polynésie Française
Résumé : The ontogeny of osmoregulation was studied in the blue shrimp Litopenaeus stylirostris in New Caledonia. The implication of branchial organs in ionic regulation was first demonstrated in juveniles by immunolocalization of three ion transporting proteins ( namely NKA, co-transporter NKCC1 and CFTR ) and ionocyte detection was done by means of electron microscopy. The role of the main ion transporting enzyme, NKA, was subsequently investigated during post-embryonic development using an integrative approach associating physiological, histological, immunological and biomolecular studies. Results obtained allowed us to propose a model of the osmoregulatory pattern in L. stylirostris based on weak regulation in the early stages, then progressively this species acquires the adult pattern of hyper-hypo-regulation after metamorphosis with the concurrent development of epipodites and gills. Strong NKA immunofluorescence and abundance of NKA transcripts in these two tissues compared to others organs suggest their functional implication in osmoregulatory processes. The results of this study allow us to increase our knowledge of the penaeid shrimp osmoregulation and to propose zootechnical measures to improve the animal physiological comfort. These propositions have been already tested during larval rearing trials, leading a two-fold-growth in 19 days-old postlarvae.
L’étude de l’ontogenèse de l’osmorégulation a été entreprise chez la crevette bleue Litopenaeus stylirostris en Nouvelle-Calédonie. L’implication des tissus de la cavité branchiale dans la régulation ionique a été déterminée au préalable chez des juvéniles par immunolocalisation de trois transporteurs protéiques d’ions, ( la NKA, le co-transporteur NKCC1 et le CFTR ) et par la détection de ionocytes en microscopie électronique. Le rôle de la NKA a été particulièrement étudié et son implication a été examinée au cours du développement post-embryonnaire par une approche intégrative associant des études physiologiques, histologiques, immunologiques et moléculaires. Cette démarche nous a permis de proposer un modèle d’osmorégulation chez L. stylirostris: de faible régulatrice dans les premiers jours de sa vie, cette espèce évolue vers l’hyper-hypo-régulation après la métamorphose avec le développement progressif des épipodites et des branchies. L’immunofluorescence prononcée de la NKA ainsi que l’abondance des transcrits du gène codant la NKA dans les tissus de ces deux organes suggèrent leur implication fonctionnelle dans l’ionorégulation. Les résultats de ce travail nous ont permis d’accroître nos connaissances sur l’osmorégulation chez les pénéidés et de proposer des améliorations zootechniques visant à augmenter leur confort physiologique. Ces préconisations ont fait l’objet de premiers essais en conditions d’élevage et se sont traduites par un doublement de la croissance des post-larves de 19 jours.

Droits : 2011 The author, Univ. Polynésie Française
http://archimer.ifremer.fr/doc/00052/16314/13816.pdf
http://archimer.ifremer.fr/doc/00052/16314/

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
BACKGROUND: Mammalian spermatogenesis is a process that involves a complex expression program in both somatic and germ cells present in the male gonad. A number of studies have attempted to define the transcriptome of male meiosis and gametogenesis in rodents and primates. Few human transcripts, however, have been associated with testicular somatic cells and germ cells at different post-natal developmental stages and little is known about their level of germline-specificity compared with non-testicular tissues. METHODS: We quantified human transcripts using GeneChips and a total of 47 biopsies from prepubertal children diagnosed with undescended testis, infertile adult patients whose spermatogenesis is arrested at consecutive stages and fertile control individuals. These results were integrated with data from enriched normal germ cells, non-testicular expression data, phenotype information, predicted regulatory DNA-binding motifs and interactome data. RESULTS: Among 3580 genes for which we found differential transcript concentrations in somatic and germ cells present in human testis, 933 were undetectable in 45 embryonic and adult non-testicular tissues, including many that were corroborated at protein level by published gene annotation data and histological high-throughput protein immunodetection assays. Using motif enrichment analyses, we identified regulatory promoter elements likely involved in germline development. Finally, we constructed a regulatory disease network for human fertility by integrating expression signals, interactome information, phenotypes and functional annotation data. CONCLUSIONS: Our results provide broad insight into the post-natal human testicular transcriptome at the level of cell populations and in a global somatic tissular context. Furthermore, they yield clues for genetic causes of male infertility and will facilitate the identification of novel cancer/testis genes as targets for cancer immunotherapies.
ISSN: 0268-1161

hal-00877243
https://hal.archives-ouvertes.fr/hal-00877243
DOI : 10.1093/humrep/des301
PUBMED : 22926843

Éditeur(s) : HAL CCSD
Résumé : International audience
Studies report that foetal exposure to paracetamol by maternal consumption can interfere with male reproductive development. Moreover, recent biomonitoring data report widespread presence of paracetamol in German and Danish populations, suggesting exposure via secondary (non-pharmaceutical) sources such as metabolic conversion from the ubiquitous industrial compound aniline. In this study we investigated the extent to which paracetamol and aniline can interfere with female reproductive development. Intrauterine exposure to paracetamol by gavage of pregnant dams resulted in shortening of the anogenital distance in adult offspring, suggesting that foetal hormone signalling had been disturbed. Female offspring of paracetamol-exposed mothers had ovaries with diminished follicle reserve and reduced fertility. Foetal gonads of exposed animals had also reduced gonocyte numbers, suggesting that the reduced follicle count in adults could be due to early disruption of germ cell development. However, ex vivo cultures of ovaries from 12.5 days post coitum foetuses showed no decrease in proliferation or expression following exposure to paracetamol. This suggests that the effect of paracetamol occurs prior to this developmental stage. Accordingly, using embryonic stem cells as a proxy for primordial germ cells we show that paracetamol is an inhibitor of cellular proliferation, but without cytotoxic effects. Collectively, our data show that intrauterine exposure to paracetamol at levels commonly observed in pregnant women, as well as its precursor aniline, may block primordial germ cell proliferation, ultimately leading to reduced follicle reserves and compromised reproductive capacity later in life
Toxicological Sciences

hal-01259211
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01259211
DOI : 10.1093/toxsci/kfv332
PUBMED : 26732887

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
The Hedgehog (Hh) family of secreted proteins act as morphogens to control embryonic patterning and development in a variety of organ systems. Post-translational covalent attachment of cholesterol and palmitate to Hh proteins are critical for multimerization and long range signaling potency. However, the biological impact of lipid modifications on Hh ligand distribution and signal reception in humans remains unclear. In the present study, we report a unique case of autosomal recessive syndromic 46,XY Disorder of Sex Development (DSD) with testicular dysgenesis and chondrodysplasia resulting from a homozygous G287V missense mutation in the hedgehog acyl-transferase (HHAT) gene. This mutation occurred in the conserved membrane bound O-acyltransferase (MBOAT) domain and experimentally disrupted the ability of HHAT to palmitoylate Hh proteins such as DHH and SHH. Consistent with the patient phenotype, HHAT was found to be expressed in the somatic cells of both XX and XY gonads at the time of sex determination, and Hhat loss of function in mice recapitulates most of the testicular, skeletal, neuronal and growth defects observed in humans. In the developing testis, HHAT is not required for Sertoli cell commitment but plays a role in proper testis cord formation and the differentiation of fetal Leydig cells. Altogether, these results shed new light on the mechanisms of action of Hh proteins. Furthermore, they provide the first clinical evidence of the essential role played by lipid modification of Hh proteins in human testicular organogenesis and embryonic development.
ISSN: 1553-7390

hal-01063929
https://hal.archives-ouvertes.fr/hal-01063929
DOI : 10.1371/journal.pgen.1004340
PUBMED : 24784881

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
In contrast to mammals that have limited proliferation and neurogenesis capacities, the Xenopus frog exhibit a great potential regarding proliferation and production of new cells in the adult brain. This ability makes Xenopus a useful model for understanding the molecular programs required for adult neurogenesis. Transcriptional factors that control adult neurogenesis in vertebrate species undergoing widespread neurogenesis are unknown. NeuroD1 is a member of the family of proneural genes, which function during embryonic neurogenesis as a potent neuronal differentiation factor. Here, we study in detail the expression of NeuroD1 gene in the juvenile and adult Xenopus brains by in situ hybridization combined with immunodetections for proliferation markers (PCNA, BrdU) or in situ hybridizations for cell type markers (Vimentin, Sox2). We found NeuroD1 gene activity in many brain regions, including olfactory bulbs, pallial regions of cerebral hemispheres, preoptic area, habenula, hypothalamus, cerebellum and medulla oblongata. We also demonstrated by double staining NeuroD1/BrdU experiments, after long post-BrdU administration survival times, that NeuroD1 gene activity was turned on in new born neurons during post-metamorphic neurogenesis. Importantly, we provided evidence that NeuroD1-expressing cells at this brain developmental stage were post-mitotic (PCNA-) cells and not radial glial (Vimentin+) or progenitors (Sox2+) cells.
ISSN: 1932-6203

hal-00877023
https://hal-univ-rennes1.archives-ouvertes.fr/hal-00877023
https://hal-univ-rennes1.archives-ouvertes.fr/hal-00877023/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-00877023/file/The_Neurogenic_Factor-accepted.pdf
DOI : 10.1371/journal.pone.0066487

Éditeur(s) : HAL CCSD Nature Publishing Group
Résumé : International audience
Evolution involves interplay between natural selection and developmental constraints(1-3). This is seen, for example, when digits are lost from the limbs during evolution(1,3,4). Extant archosaurs (crocodiles and birds) show several instances of digit loss(3,5,6) under different selective regimes, and show limbs with one, two, three, four or the ancestral number of five digits. The `lost' digits sometimes persist for millions of years as developmental vestiges(7-10). Here we examine digit loss in the Nile crocodile and five birds, using markers of three successive stages of digit development. In two independent lineages under different selection, wing digit I and all its markers disappear. In contrast, hindlimb digit V persists in all species sampled, both as cartilage, and as Sox9-expressing precartilage domains, 250 million years after the adult digit disappeared. There is therefore a mismatch between evolution of the embryonic and adult phenotypes. All limbs, regardless of digit number, showed similar expression of sonic hedgehog (Shh). Even in the one-fingered emu wing, expression of posterior genes Hoxd11 and Hoxd12 was conserved, whereas expression of anterior genes Gli3 and Alx4 was not. We suggest that the persistence of digit V in the embryo may reflect constraints, particularly the conserved posterior gene networks associated with the zone of polarizing activity (ZPA(11)). The more rapid and complete disappearance of digit I may reflect its ZPA-independent specification, and hence, weaker developmental constraints. Interacting with these constraints are selection pressures for limb functions such as flying and perching. This model may help to explain the diverse patterns of digit loss in tetrapods. Our study may also help to understand how selection on adults leads to changes in development.
ISSN: 0028-0836

hal-01545485
https://hal.archives-ouvertes.fr/hal-01545485
DOI : 10.1038/nature12336

Éditeur(s) : HAL CCSD University of South Bohemia in Ceske Budejovice ; Faculty of Fisheries and Protection of Waters
Résumé : CRISPR/Cas9 disturbance of the multiple vitellogenin (vtg) system: essential functions of different vtg types during zebrafish egg, embryo and larval development. 6. International Workshop on the Biology of Fish Gametes
6. International Workshop on the Biology of Fish Gametes
Vodnany, Czech Republic

hal-01595005
https://hal.archives-ouvertes.fr/hal-01595005
PRODINRA : 405326

Éditeur(s) : HAL CCSD De Gruyter
Résumé : International audience
Coral reefs have undergone profound ecological changes over recent decades. Areas formerly covered by scleractinian coral species are now often overgrown by macroalgae. In Martinique (West Indies), this phenomenon has lead to the colonisation of numerous coral reefs by algae, amongst which Sargassum is one of the most prominent. This study focuses on potential defence molecules produced by Sargassum polyceratium. The hexane dipping method was employed to extract surface molecules on fresh material, and their bioactivities were assessed against bacteria (marine and estuarine), and marine tropical invertebrates wan annelid (Pseudonereis sp.), a bivalve (Codakia orbicularis) and a sea urchin (Diadema antillarum)x. Extracts were active against all microorganisms tested (MICs150 or 300 mg ml-1), early stages of development in Pseudonereis sp. (MICs100 mg ml-1) and embryos of C. orbicularis and D. antillarum (MICs5 mg ml-1), suggesting the production of defence compounds by S. polyceratium.
ISSN: 0006-8055

hal-00746082
https://hal.univ-antilles.fr/hal-00746082
https://hal.univ-antilles.fr/hal-00746082/document
https://hal.univ-antilles.fr/hal-00746082/file/Publication_Sargassum_bortanica_marina.pdf
DOI : 10.1515/BOT.2011.014

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Signalling through the Wnt family of secreted proteins originated in a common metazoan ancestor and greatly influenced the evolution of animal body plans. In bilaterians, Wnt signalling plays multiple fundamental roles during embryonic development and in adult tissues, notably in axial patterning, neural development and stem cell regulation. Studies in various cnidarian species have particularly highlighted the evolutionarily conserved role of the Wnt/b-catenin pathway in specification and patterning of the primary embryonic axis. However in another key non-bilaterian phylum, Ctenophora, Wnts are not involved in early establishment of the body axis during embryogenesis. We analysed the expression in the adult of the ctenophore Pleurobrachia pileus of 11 orthologues of Wnt signalling genes including all ctenophore Wnt ligands and Fz receptors and several members of the intracellular b-catenin pathway machinery. All genes are strongly expressed around the mouth margin at the oral pole, evoking the Wnt oral centre of cnidarians. This observation is consistent with primary axis polarisation by the Wnts being a universal metazoan feature, secondarily lost in ctenophores during early development but retained in the adult. In addition, local expression of Wnt signalling genes was seen in various anatomical structures of the body including in the locomotory comb rows, where their complex deployment suggests control by the Wnts of local comb polarity. Other important contexts of Wnt involvement which probably evolved before the ctenophore/ cnidarian/bilaterian split include proliferating stem cells and progenitors irrespective of cell types, and developing as well as differentiated neuro-sensory structures.
ISSN: 1932-6203

hal-01544483
https://hal.archives-ouvertes.fr/hal-01544483
DOI : 10.1371/journal.pone.0084363

Éditeur(s) : Station Biologique de Roscoff
Résumé : The first record of interstitial polychaetous annelids dates no more than forty years. Presently, the total number of interstitial species described is about one hundred. Up to the present, the large group of Aphroditoidea includes no interstitial representative. A few samples made by Pr Swedmark and M. Lasserre in Bermudas enable the discovery of an undescribed species of an interstitial Sigalionidae, Pholoe swedmarki Sp. n., together with two other interstitial species of Pisionidae and Syllidae, new to the western tropical atlantic. From a morphological point of view, the comparison of P. swedmarki sp. n. with the other species of the genus reveals some adaptations to the interstitial life: reduction of the body size, reduction or, at the contrary, enlargement of some appendages of the anterior part, lack of pigmentation. From the biological point of view, P. swedmarki sp. n. displays a remarkable group of characteristics : extreme reduction of the eggs numbers, extension of the reproductive period, pregnancy of the embryos and juveniles up to a very late ontogenetical stage. The hypothesis of an intra-elytral pregnancy, involving an internal fertilization, is discussed. By its morphology and biology, P. swedmarki sp. n. forms the first undeniable example of adaptation to the interstitial life among the Aphroditoidea. [NOT CONTROLLED OCR]
La découverte des premières Annélides Polychètes interstitielles remonte à peine à une quarantaine d'années. A l'heure actuelle, le nombre total d'espèces interstitielles décrites est de l'ordre d'une centaine. Jusqu'à présent, le vaste groupe des Aphroditoidea ne comprenait aucun représentant interstitiel. Quelques récoltes effectuées aux Bermudes par le Pr Swedmark et M. Lasserre ont permis de découvrir une espèce inédite de Sigalionidae interstitiel, Pholoe swedmarki sp. n., en compagnie de deux autres espèces de Pisionidae et de Syllidae interstitielles encore inconnues dans l'Atlantique tropical Ouest. Sur le plan morphologique, la comparaison de P. swedmarki sp. n. avec les autres espèces du genre met en évidence un certain nombre d'adaptations à la vie interstitielle : réduction de la taille du corps, réduction ou, au contraire, développement de certains appendices de la région antérieure, absence de pigmentation. Du point de vue biologique, P. swedmarki sp. n. présente un ensemble d'adaptations remarquables : réduction extrême du nombre d'oeufs, allongement de la période de reproduction, gestation des embryons et des jeunes vers jusqu'à un stade ontogénétique très avancé. L'hypothèse d'une gestation intra-élytrale, impliquant une fécondation interne, est avancée. Par sa morphologie et sa biologie, P. swedmarki sp. n. constitue le premier exemple incontestable d'adaptation à la vie interstitielle chez un Aphroditoidea. [OCR NON CONTRÔLE]
Cahiers de Biologie Marine (Station Biologique de Roscoff), 1974 , Vol. 16 , N. 5 , P. 671-683

Droits : Station Biologique de Roscoff
http://archimer.ifremer.fr/doc/1974/publication-5462.pdf
http://archimer.ifremer.fr/doc/00000/5462/

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
Neurogenesis initiates during early development and it continues through later developmental stages and in adult animals to enable expansion, remodeling, and homeostasis of the nervous system. The generation of nerve cells has been analyzed in detail in few bilaterian model organisms, leaving open many questions about the evolution of this process. As the sister group to bilaterians, cnidarians occupy an informative phylogenetic position to address the early evolution of cellular and molecular aspects of neurogenesis and to understand common principles of neural development. Here we review studies in several cnidarian model systems that have revealed significant similarities and interesting differences compared to neurogenesis in bilaterian species, and between different cnidarian taxa. Cnidarian neurogenesis is currently best understood in the sea anemone Nematostella vectensis, where it includes epithelial neural progenitor cells that express transcription factors of the soxB and atonal families. Notch signaling regulates the number of these neural progenitor cells, achaete-scute and dmrt genes are required for their further development and Wnt and BMP signaling appear to be involved in the patterning of the nervous system. In contrast to many vertebrates and Drosophila, cnidarians have a high capacity to generate neurons throughout their lifetime and during regeneration. Utilizing this feature of cnidarian biology will likely allow gaining new insights into the similarities and differences of embryonic and regenerative neurogenesis. The use of different cnidarian model systems and their expanding experimental toolkits will thus continue to provide a better understanding of evolutionary and developmental aspects of nervous system formation.
ISSN: 1759-7692

Droits : http://creativecommons.org/licenses/by-nc/
hal-01405097
http://hal.upmc.fr/hal-01405097
http://hal.upmc.fr/hal-01405097/document
http://hal.upmc.fr/hal-01405097/file/Rentzsch_et_al-2016-Wiley_Interdisciplinary_Reviews__Developmental_Biology.pdf
DOI : 10.1002/wdev.257

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
The embryonic development in Chione cancellata, from fertilization to straighthinge D-stage veliger larva, occurs in 24 h at 251C. Transmission (TEM) and scanning (SEM) electron microscopy show that morphogenetic processes result in a gastrula with two depressions, 4 h after fertilization (T014 h). Two hours later, one depression, located at the animal pole, develops into an open cave, the floor of which becomes the shell field, characterized by scarce microvilli, located below the lower face of the prototrochal pad. The invagination located at the vegetal pole is characterized by regular microvilli and constitutes the digestive tract. At T018 h, the late gastrula differentiates into a typical motile trochophore, possessing a well-developed prototroch delimiting anterior and posterior embryonic regions. At T019h, the shell field, located between the prototroch and the telotroch, appears as a saddle-shaped region with a wrinkled surface extending on both sides of the embryo, establishing bilateral symmetry. From TEM observations, the apical surface of the underlying cells possesses a modified glycocalyx featuring a dense pellicle overlapping the cells of the shell field. At T0112 h, the prototroch is displaced toward the anterior region by outgrowth of the shell material. TEM views show that the wrinkled surface observed with SEM corresponds to the periostracum, attached dorsally to the hinge and ventrally to the cells of the future mantle edge. At T0115 h, an alveolar matrix of proteinaceous material, which could contain calcite crystals, appears between the periostracum and the mantle. At T0124 h, prodissoconch I formation is completed and the D-stage larvae possess a calcified shell. At this stage of development, only one mantle fold is present, representing the outer fold. The periostracumsecreting cells are in contact with the marginal cells of the velum. This functional velum is composed of four bands of cilia. Our TEMobservations confirm previous descriptions of the velum ciliary bands obtained only from SEM analyses, such as described in other bivalves. The apical sense organ and the digestive tract are poorly developed. From observations at the ultrastructural level of shell differentiation in C. cancellata, we propose a new interpretation of shell differentiation, including hinge and ligament for bivalves as opposed to that described for gastropods.
ISSN: 1077-8306

hal-00755283
https://hal.univ-antilles.fr/hal-00755283
DOI : 10.1111/j.1744-7410.2006.00036.x

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
Cytochrome P450 aromatase (P450arom; aromatase) is a microsomal enzyme involved in the production of endogeneous sex steroids by converting testosterone into oestradiol. Aromatase is the product of the cyp19a1 gene and plays a crucial role in the sexual differentiation of the brain and in the regulation of reproductive functions. In the brain of mammals and birds, expression of cyp19a1 has been demonstrated in neuronal populations of the telencephalon and diencephalon. By contrast, a wealth of evidence established that, in teleost fishes, aromatase expression in the brain is restricted to radial glial cells. The present study investigated the precise neuroanatomical distribution of cyp19a1 mRNA during brain development in Xenopus laevis (late embryonic to juvenile stages). For this purpose, we used in situ hybridisation alone or combined with the detection of a proliferative (proliferating cell nuclear antigen), glial (brain lipid binding protein, Vimentin) or neuronal (acetylated tubulin; HuC/D; NeuroβTubulin) markers. We provide evidence that cyp19a1 expression in the brain is initiated from the very early larval stage and remains strongly detected until the juvenile and adult stages. At all stages analysed, we found the highest expression of cyp19a1 in the preoptic area and the hypothalamus compared to the rest of the brain. In these two brain regions, cyp19a1-positive cells were never detected in the ventricular layers. Indeed, no co-labelling could be observed with radial glial (brain lipid binding protein, Vimentin) or dividing progenitors (proliferating cell nuclear antigen) markers. By contrast, cyp19a1-positive cells perfectly matched with the distribution of post-mitotic neurones as shown by the use of specific markers (HuC/D, acetylated tubulin and NeuroβTubulin). These data suggest that, similar to that found in other tetrapods, aromatase in the brain of amphibians is found in post-mitotic neurones and not in radial glia as reported in teleosts.
ISSN: 0953-8194

hal-00994513
https://hal-univ-rennes1.archives-ouvertes.fr/hal-00994513
DOI : 10.1111/jne.12142
PUBMED : 24612124

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
The implication of oxidative stress as primary mechanism inducing doxorubicin (DOX) cardiotoxicity is still questionable as many in vitro studies implied supra-clinical drug doses or unreliable methodologies for reactive oxygen species (ROS) detection. The aim of this study was to clarify whether oxidative stress is involved in compliance with the conditions of clinical use of DOX, and using reliable tools for ROS detection. We examined the cytotoxic mechanisms of 2 μM DOX 1 day after the beginning of the treatment in differentiated H9c2 rat embryonic cardiac cells. Cells were exposed for 2 or 24 h with DOX to mimic a single chronic dosage or to favor accumulation, respectively. We found that apoptosis was prevalent in cells exposed for a short period with DOX: cells showed typical hallmarks as loss of anchorage ability, mitochondrial hyperpolarization followed by the collapse of mitochondrial activity, and nuclear condensation. Increasing the exposure period favored a shift to necrosis as the cells preferentially exhibited early DNA impairment and nuclear swelling. In either case, measuring the fluorescence lifetime of 1-pyrenebutyric acid or the intensities of dihydroethidium or amplex red showed a consistent pattern in ROS production which was a slight increased level far from representative of an oxidative stress. Moreover, pre-treatment with dexrazoxane provided a cytoprotective effect although it failed to detoxify ROS. Our data support that oxidative stress is unlikely to be the primary mechanism of DOX cardiac toxicity in vitro.
ISSN: 0300-8177

hal-01285736
https://hal-univ-perp.archives-ouvertes.fr/hal-01285736
DOI : 10.1007/s11010-016-2653-x

Éditeur(s) : HAL CCSD
Résumé : International audience
Estrogens affect brain development of vertebrates, not only by impacting activity and morphology of existing circuits, but also by modulating embryonic and adult neurogenesis. The issue is complex as estrogens can not only originate from peripheral tissues, but also be locally produced within the brain itself due to local aromatization of androgens. In this respect, teleost fishes are quite unique because aromatase is expressed exclusively in radial glial cells, which represent pluripotent cells in the brain of all vertebrates. Expression of aromatase in the brain of fish is also strongly stimulated by estrogens and some androgens. This creates a very intriguing positive auto-regulatory loop leading to dramatic aromatase expression in sexually mature fish with elevated levels of circulating steroids. Looking at the effects of estrogens or anti-estrogens in the brain of adult zebrafish showed that estrogens inhibit rather than stimulate cell proliferation and newborn cell migration. The functional meaning of these observations is still unclear, but these data suggest that the brain of fish is experiencing constant remodeling under the influence of circulating steroids and brain-derived neurosteroids, possibly permitting a diversification of sexual strategies, notably hermaphroditism. Recent data in frogs indicate that aromatase expression is limited to neurons and do not concern radial glial cells. Thus, until now, there is no other example of vertebrates in which radial progenitors express aromatase. This raises the question of when and why these new features were gained and what are their adaptive benefits. This article is part of a Special Issue entitled: Nuclear receptors in animal development.
Biochimica et Biophysica Acta (BBA) - Gene Regulatory Mechanisms

Droits : info:eu-repo/semantics/OpenAccess
hal-01102449
https://hal.archives-ouvertes.fr/hal-01102449
https://hal.archives-ouvertes.fr/hal-01102449/document
https://hal.archives-ouvertes.fr/hal-01102449/file/Coumailleau%20et%20al%20final%20manuscript.pdf
DOI : 10.1016/j.bbagrm.2014.07.002