Post-ovulatory ageing and egg quality: A proteomic analysis of rainbow trout coelomic fluid

BACKGROUND: In fish, oocyte post-ovulatory ageing is associated with egg quality decrease. During this period, eggs are held in the body cavity where they bath in a semi-viscous liquid known as coelomic fluid (CF). CF components are suspected to play a role in maintaining oocyte fertility and developmental competence (egg quality). However, CF proteic composition remains poorly studied. Thus rainbow trout CF proteome was studied during the egg quality decrease associated with oocyte post-ovulatory ageing. METHODS: High resolution two-dimensional gel electrophoresis was used to analyze the proteome of rainbow trout (Oncorhynchus mykiss) CF in relationship with the egg quality decrease associated with oocyte post-ovulatory ageing. A first experiment was performed using CF pools originating from 17 females sampled at ovulation as well as 7, 14 and 21 days later. These observations were verified using a second set of CF pools originating from 22 females sampled 5 and 16 days following ovulation. RESULTS: Approximately 200 protein spots of 10–105 kDa molecular mass and 3–10 pI were detected in CF samples. Several protein spots, while undetected at the time of ovulation, exhibited a progressive and strong accumulation in CF during post-ovulatory ageing. After silver-staining and Matrix-Assisted Laser Desorption Time Of Flight (MALDI-TOF) mass spectrometer analysis, some of these protein spots were identified as lipovitellin II fragments. CONCLUSIONS: These observations suggest that egg protein fragments accumulate in the CF during the post-ovulatory period and could therefore be used to detect egg quality defects associated with oocyte post-ovulatory ageing

Histoire et anthropologie de la parenté

Gérard Delille, Françoise Héritier, directeurs d’étudesLaurent Barry, maître de conférencesAnita Guerreau-Jalabert, directrice de recherche au CNRSBernard Derouet, chargé de recherche au CNRS Compte rendu non communiqu

Processing of functional fine scale ceramic structures by ink-jet printing

International audienceThis review illustrates the potentiality of ink-jet printing for the fabrication of functional fine scale ceramic structures corresponding to two different kinds of micro-pillar arrays i.e. (i) PZT skeletons, etc..

Contrôle de la reproduction par les facteurs externes chez les poissons

Contrôle de la reproduction par les facteurs externes chez les poisson

An overview of 30 years of international research in some selected fields of the reproductive physiology of fish

Présentation oraleNational audienceThe main scientific fields involved in the 8th International Symposium on the Reproductive Physiology of Fish (ISRPF) are defined and placed within the context of the socio-economic evolution since the first ISRPF, 30 years ago. Some important scientific advances during that period are mentioned in selected fields: gonadotropins and gonadotropin releasing hormones (GnRH) as key regulators of reproductive function; and puberty as an example of a reproductive trait dependant on specific reproductive strategies, exhibiting various reproductive tactics and regulated by a cascade of endocrine, paracrine and autocrine factors. Some examples of economically relevant applications of RPF knowledge are recalled

Particularities of reproduction and oogenesis in teleost fish compared to mammals

Compared to mammals, teleost reproduction presents many original features. Reproductive strategies of species are diversified into numerous adaptations to a large variety of aquatic environments. This diversity may concern sexuality, spawning and parental behaviour, sensitivity to environmental factors, and specific features of gametogenesis such as the duration of vitellogenesis, and egg morphology. Sexuality presents a variety of natural modalities, from gonochorism to hermaphrodism. The absence of definitive arrest of body growth in the adult of most species gives a particular interest to the practical control of growth-reproduction interactions. Vitellogenesis, which represents an important metabolic effort for the maternal organism, involves the synthesis of vitellogenin, a specific glycolipo-phosphoprotein produced in the liver under estradiol stimulation, and its incorporation into oocytes by a receptor mediated process. Both estradiol synthesis in follicle cells and vtg uptake by vitellogenic follicles appear to be mainly controlled by FSH. Oocyte maturation is directly triggered by a progestin, or MIS (maturation inducing steroid) synthesised in follicle cells mainly under LH control, and acting through the non-genomic activation of a membrane receptor. Practical applications of some of these particularities result mainly from the external character of the fertilisation process and of embryonic development, which allows manipulating respectively egg chromosome stocks and sex differentiation. Moreover, the sensitivity of sex differentiation to exogenous factors favours the development of practical methods to control the sex of farmed populations. Finally, the sensitivity of reproductive mechanisms to xenobiotics has led to various kinds of bioassays for putative pollutants

In vitro oocyte maturation and ovulation in rainbow trout (salmo gairdneri), Northern Pike (Esox lucius), and goldfish (Carassius auratus)

The endocrine processes which control oocyte maturation (resumption of meiosis) and ovulation have been studied in vitro in the trout Salmo gairdneri. Follicular maturation is ultimately under the control of a pituitary gonadotropin which induces the follicle to synthesize specific steroids; these steroids act in turn directly on the oocyte to promote maturation. The systematic study of the in vitro efficiency of various steroids have shown that 17alpha-hydroxy- 20beta-dihydroprogesterone plays a preferential role in initiating maturation; this steroid has a high affinity for a plasma protein system. The efficiency of this steroid, similarly to the efficiency of the gonadotropin, can be modulated by other circulating steroids. The precise chronology of some events of follicle maturation have been defined using inhibitors of protein and RNA synthesis. The ovulatory process (sensu stricto: expulsion of matured oocyte from the follicular envelopes) has been experimentally dissociated from oocyte maturation, and some mediators likely to act on ovulation have been identified. These data permit the consideration of novel means of intervention at the ovarian level to synchronize maturation and ovulation in fish, in order to give new tools for progress in aquaculture.Nous avons étudié in vitro les processus endocrines qui contrôlent la maturation des ovocytes (reprise de la meiose) et l'ovulation chez la truite arc-en-ciel, Salmo gairdneri. La maturation folliculaire est en dernier lieu sous le contrôle d'une gonadotropine hypophysaire qui déclenche dans le follicule la synthèse de stéroides spécifiques; ces stéroides, à leur tour, agissent directement sur l'ovocyte et activent la maturation. L'étude systématique de l'efficacité in vitro de divers stéroides démontre que la 17alpha hydroxy-20beta dihydroprogesterone joue un rôle préférentiel dans l'amorcage de la maturation; ce stéroide à une haute affinité pour un système de protéines plasmiques. L'efficacité de ce stéroide, tout comme celle de la gonadotropine, peut être modulée par d'autres stéroïdes en circulation. Nous avons défini, à l'aide d'inhibiteurs de protéines et synthèse de la RNA, la chronologie précise de certaines étapes de maturation des follicules. Le processus d'ovulation (sensu stricto: expulsion de l'ovocyte mûr des enveloppes folliculaires) a été dissocié expérimentalement de la maturation de l'ovocyte, et certains médiateurs susceptibles d'activer l'ovulation ont été identifiées. Grâce à ces données, on peut considérer de nouveaux moyens d'intervenir au niveau ovarien pour synchroniser la maturation et l'ovulation chez les poissons, fournissant ainsi de nouveaux outils pour le progrès de l'aquaculture