Expression profiling of rainbow trout testis development identifies evolutionary conserved genes involved in spermatogenesis.

Chantier qualité GAInternational audienceBACKGROUND: Spermatogenesis is a late developmental process that involves a coordinated expression program in germ cells and a permanent communication between the testicular somatic cells and the germ-line. Current knowledge regarding molecular factors driving male germ cell proliferation and differentiation in vertebrates is still limited and mainly based on existing data from rodents and human. Fish with a marked reproductive cycle and a germ cell development in synchronous cysts have proven to be choice models to study precise stages of the spermatogenetic development and the germ cell-somatic cell communication network. In this study we used 9K cDNA microarrays to investigate the expression profiles underlying testis maturation during the male reproductive cycle of the trout, Oncorhynchus mykiss. RESULTS: Using total testis samples at various developmental stages and isolated spermatogonia, spermatocytes and spermatids, 3379 differentially expressed trout cDNAs were identified and their gene activation or repression patterns throughout the reproductive cycle were reported. We also performed a tissue-profiling analysis and highlighted many genes for which expression signals were restricted to the testes or gonads from both sexes. The search for orthologous genes in genome-sequenced fish species and the use of their mammalian orthologs allowed us to provide accurate annotations for trout cDNAs. The analysis of the GeneOntology terms therefore validated and broadened our interpretation of expression clusters by highlighting enriched functions that are consistent with known sequential events during male gametogenesis. Furthermore, we compared expression profiles of trout and mouse orthologs and identified a complement of genes for which expression during spermatogenesis was maintained throughout evolution. CONCLUSION: A comprehensive study of gene expression and associated functions during testis maturation and germ cell differentiation in the rainbow trout is presented. The study identifies new pathways involved during spermatogonia self-renewal or rapid proliferation, meiosis and gamete differentiation, in fish and potentially in all vertebrates. It also provides the necessary basis to further investigate the hormonal and molecular networks that trigger puberty and annual testicular recrudescence in seasonally breeding species

Modifications des conditions d'extraction du lait sous l'effet d'un β-mimétique (Isoprénaline) administré par voie intrajugulaire pendant la traite mécanique de la vache

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Effets de l'adrénaline et de la phényléphrine sur l'extraction du lait au cours de la traite mécanique de la vache

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Effets de l'adrénaline et de la phényléphrine sur l'extraction du lait au cours de la traite mécanique de la vache

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Effets de l'adrénaline et de la phényléphrine sur l'extraction du lait au cours de la traite mécanique de la vache

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Involvement of estrogens in the process of sex differentiation in rainbow trout <em>(Oncorhynchus mykiss)</em>: <em>In vivo</em> treatments, aromatase activity, and aromatase gene expression

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Involvement of estrogens in the process of sex differentiation in rainbow trout <em>(Oncorhynchus mykiss)</em>: <em>In vivo</em> treatments, aromatase activity, and aromatase gene expression

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Application of a recombinant cichlid growth hormone radioimmunoassay to measure native GH in tilapia

This work describes the application of a homologous radioimmunoassay (RIA) in the measurement of plasma and pituitary growth hormone levels of tilapia maintained at 20 and 26 °C, using recombinant tilapia growth hormone (rtiGH). RIA sensitivity (ED90) was 0.08 ng/ml and ED50 was 0.62 ± 0.02 ng/ml. Intra- and inter-assay coefficients of variation were 3.3 and 10.6% respectively, for a plasma sample of 1 ng/ml of tiGH. Mammalian or salmonids growth hormones, thyrotropins or tilapia prolactins did not show cross-reactivity with rtiGH antiserum. Plasma and pituitary extract of Oreochromis niloticus gave inhibition curves parallel to the rtiGH standard curve without interaction with serial dilutions either of tissue extracts or plasma from hypophysectomized tilapia. Pituitary extracts from other cichlid fish showed parallel competitive binding curves. Pituitary extracts of perciform fish exhibited a lower affinity to anti- rtiGH serum, while extracts of species from more distant families showed only negligible cross-reactivity or none at all. The effects of water temperature on plasma concentrations and pituitary contents of GH were investigated in tilapia acclimatized to 26 and to 20 °C. Measurements have been performed at the beginning and at the end of a two-week experiment. Whereas in fish from colder water plasma GH mean values were decreased, only a similar tendency was observed in pituitary GH contents. These results emphasize the hypothesis wich reports that the increase of growth with temperature is, at least in part, controlled by GH

Growth hormone retrocontrol in rainbow trout (Oncorhynchus mykiss): effect of starvation

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