Effect of temperature, food availability, and estradiol injection on gametogenesis and gender in the pearl oyster Pinctada margaritifera.
The black-lip pearl oyster Pinctada margaritifera is a protandrous hermaphrodite species. Its economic value has led to the development of controlled hatchery reproduction techniques, although many aspects remain to be optimized. In order to understand reproductive mechanisms and their controlling factors, two independent experiments were designed to test hypotheses of gametogenesis and sex ratio control by environmental and hormonal factors. In one, pearl oysters were exposed under controlled conditions at different combinations of temperature (24 and 28°C) and food level (10,000 and 40,000 cells mL(-1) ); whereas in the other, pearl oysters were conditioned under natural conditions into the lagoon and subjected to successive 17β-estradiol injections (100 μg per injection). Gametogenesis and sex ratio were assessed by histology for each treatment. In parallel, mRNA expressions of nine marker genes of the sexual pathway (pmarg-foxl2, pmarg-c43476, pmarg-c45042, pmarg-c19309, pmarg-c54338, pmarg-vit6, pmarg-zglp1, pmarg-dmrt, and pmarg-fem1-like) were investigated. Maximum maturation was observed in the treatment combining the highest temperature (28°C) and the highest microalgae concentration (40,000 cells mL(-1) ), where the female sex tended to be maintained. Injection of 17β-estradiol induced a significant increase of undetermined stage proportion 2 weeks after the final injection. These results suggest that gametogenesis and gender in adult pearl oysters can be controlled by environmental factors and estrogens. While there were no significant effects on relative gene expression, the 3-gene-pair expression ratio model of the sexual pathway of P. margaritifera, suggest a probable dominance of genetic sex determinism without excluding a mixed sex determination mode (genetic + environmental). J. Exp. Zool. 325A:13-24, 2016. © 2015 Wiley Periodicals, Inc.
Ifremer, UMR 241 Ecosystèmes Insulaires Océaniens (EIO), Labex CORAIL, Centre du Pacifique, Taravao, Tahiti, French Polynesia.
Vaihiti
V
Teaniniuraitemoana
Ifremer, UMR 241 Ecosystèmes Insulaires Océaniens (EIO), Labex CORAIL, Centre du Pacifique, Taravao, Tahiti, French Polynesia.
Maxime
M
Leprêtre
Ifremer, UMR 241 Ecosystèmes Insulaires Océaniens (EIO), Labex CORAIL, Centre du Pacifique, Taravao, Tahiti, French Polynesia.
Peva
P
Levy
Ifremer, UMR 241 Ecosystèmes Insulaires Océaniens (EIO), Labex CORAIL, Centre du Pacifique, Taravao, Tahiti, French Polynesia.
Vincent
V
Vanaa
Ifremer, UMR 241 Ecosystèmes Insulaires Océaniens (EIO), Labex CORAIL, Centre du Pacifique, Taravao, Tahiti, French Polynesia.
Sophie
S
Parrad
Université de la Polynésie Française, UMR 241 Ecosystèmes Insulaires Océaniens (EIO), Labex CORAIL, Faa'a, Tahiti, French Polynesia.
Nabila
N
Gaertner-Mazouni
Ifremer, UMR 5244 Interactions Hôtes-Pathogènes-Environnement (IHPE), Université de Montpellier, Montpellier Cedex 5, France.
Yannick
Y
Gueguen
Ifremer, UMR 6539 Laboratoire des sciences de l'Environnement Marin (LEMAR), ZI de la Pointe du Diable, Plouzané, France.
Arnaud
A
Huvet
Ifremer, UMR 241 Ecosystèmes Insulaires Océaniens (EIO), Labex CORAIL, Centre du Pacifique, Taravao, Tahiti, French Polynesia.
Gilles
G
Le Moullac
D000818:Animals; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D005502:Food; D005718:Gametogenesis / Q000235:genetics / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D008297:Male; D049911:Pinctada / Q000235:genetics / Q000502:physiology*; D012333:RNA, Messenger / Q000096:biosynthesis; D019849:Sex Determination Processes / Q000235:genetics*; D012744:Sex Ratio; D013696:Temperature
D012333:RNA, Messenger; D004958:Estradiol