Comparative study of reproductive biology in single and multiple‐spawner cyprinid fish. II. Sex steroid and plasma protein phosphorus concentrations

Abstract

The dynamics and regulation of oogenesis in single and multiple-spawner cyprinid fish showing group-synchronous oocyte development, was investigated in three species from the River Meuse (Belgium): the roach Rutilus rutilus as a single spawner, and the bleak Alburnus alburnus and the white bream Blicca bjoerkna as multiple spawners. This paper compares the seasonal profiles of sex steroids (oestradiol-17 , testosterone and 17,20 -dihydroxy-4-pregnen-3-one) and plasma alkali-labile protein phosphorus. Different patterns of plasma oestradiol-17 (E2) and plasma protein phosphorus (PPP) have been observed not only between the single and the multiple spawner fish, but also among the two multiple spawners. In roach, two increases of E2 levels were observed. The first occurred in September after a short gonadal quiescent period, and coincided with the increase of the PPP at the onset of exogenous vitellogenesis. The second took place in spring before the spawning season. The low PPP recorded during that period probably reflected its rapid incorporation by the oocytes. In both multiple spawners, highest values of PPP were recorded just before the spawning season. In white bream, the PPP declined progressively once the differentiation of exogenous vitellogenic oocytes was completed before the onset of the spawning season. In bleak, PPP levels remained high throughout the spawning season and corresponded to a sustained oocyte recruitment during the whole of this period. Regardless of the pattern of oocyte growth recruitment, the E2 concentrations were high in both multiple spawner species during the breeding season. In the three species, testosterone levels remained low regardless of the maturation stage (ranging from 0·6 to 13·4 ng ml 1 ). Except for relatively high concentrations of 17,20 P in roach during final maturation and postspawning stages (20 and 28 ng ml 1 , respectively), low levels of this steroid were measured in these cyprinids, and especially in the multiple spawner fish. The role of this progestogen as the maturation inducing steroid is discussed. 1997 The Fisheries Society of the British Isles

The three-spined stickleback as an environmental sentinel: effects of stressors on whole-body physiological indices

“…Therefore measurement of protein-associated phosphorous in the blood of vitellogenic vertebrates (or invertebrates) provides an indirect measure of vitellogenin in the blood (Rinchard et al, 1997). The measurement of plasma alkali-labile phosphorous (ALP; phosphoprotein phosphorous) levels has been employed as a surrogate for direct assay of vitellogenin (VTG) in several species of fish both in vivo (deVlaming et al, 1984;Pereira et al, 1992;Kramer et al, 1998;Ko et al, 1999) and in vitro (Gagné & Blaise, 1998) and it is well-established that there is a direct relationship between plasma levels of ALP and circulating vitellogenin concentrations (Bjoernsson & Haux, 1985;Nagler et al, 1987;T.…”

Croissance ovocytaire et régulation stéroïdienne chez les poissons à pontes unique et multiples : une revue

“…Chez de nombreux poissons, la vitellogenèse exogène s'accompagne d'un accroissement du niveau de la 17P-oestradiol (E2) (Tableau 2). De nombreux auteurs établissent une bonne corrélation entre l'indice gonadosomatique (exprimé comme le rapport entre le poids des gonades et le poids total du poisson) et le taux d'E2 au cours de la vitellogenèse exogène, preuve indirecte que cette hormone est bien impliquée dans le contrôle de la synthèse de la vitellogénine par le foie (Ng & Idler 1983, Galas & Bieniarz 1989, Carragher & Pankhurst 1993, Rinchard et al 1993et 1997. En plus de cette participation à la synthèse de vitellogénine, les oestrogènes stimulent la synthèse, par le foie, de protéines membranaires (choriogénines) de l'oeuf (Hamazaki et al 1987, Hyllner & Haux 1995, LaFleur et al 1995.…”

“…Les faibles taux de PPP enregistrés à cette période (Fig. 3) reflètent probablement l'incorporation rapide du PPP dans les ovocytes (Rinchard 1996, Rinchard et al 1997). Ce type de profil bimodal de l'E2 est également observé chez d'autres espèces, comme chez le poisson-chat, Ictalurus nebulosus LeSueur (Burke et al 1984), la dorade royale, Spams aurata L. (Kadmon et al 1985), le Morone americana Gmelin.…”

“…3) Prat et al 1990, Rinchard et al 1993). Toutefois, chez certaines espèces, comme le poissonchat Ictalarus punctatus (Burke et al 1984), le doré jaune (Malison et al 1994), le bar commun (Prat et al 1990), le gardon (Rinchard et al 1997), deux pics distincts de T ont pu être observés au cours du cycle reproducteur annuel. Le premier pic correspond généra-lement à la reprise de la vitellogenèse et l'augmentation rapide de la concentration d'E2.…”

“…Enfin, signalons que, chez de nombreuses espèces, des niveaux élevés de stéroïdes sont observés lorsque les ovaires sont en postponte , Rinchard et al 1993et 1997. A ce stade, les ovaires ne contiennent plus que des ovocytes prévitellogéniques, des follicules atrétiques postovulatoires, mais également des ovocytes vitellogéniques non ovules en régression.…”