HAL Id: hal-02778210
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Involvement of 11-beta oxygenated androgens in
testicular differentiation ; temperature effect on
11-beta-hydroxylase activity in the mechanisms of
temperature sensitivity of gonadal sex differentiation in
Oreochromis niloticus
Jean-François Baroiller, Alexis Fostier, Bernard Jalabert
To cite this version:
Jean-François Baroiller, Alexis Fostier, Bernard Jalabert. Involvement of 11-beta oxygenated andro-gens in testicular differentiation ; temperature effect on 11-beta-hydroxylase activity in the mechanisms of temperature sensitivity of gonadal sex differentiation in Oreochromis niloticus. 2. International Symposium on Fish Endocrinology, Jun 1992, Saint-Malo, France. 116 p., 1992. �hal-02778210�
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MINISTERE DE LA RECHERCHE ET DE LA TECHNOLOGIE VIL l E DE SAINT-MALO lmp. Université RenneINVOLVEMENT OF llB-OXYGENATED ANDROGENS IN TESTICULAR DIFFERENTIATION; TEMPERATURE EFFECTS ON llB-HYDROXYLASE ACTIVITY IN THE MECHANISMS OF TEMPERATURE SENSITIVITY OF
GONADAL SEX DIFFERENTIATION IN-OREOCHROMIS NILOTICUS
J.F. BAROILLER1
• 2 • 3 1 A. FOSTIER
2 and B. JALABERT2
1Laboratoire de Physiologie des Poissons, INRA, Campus de
Beaulieu, 35042 RENNES Cédex, FRANCE.
2 Département Piscicole, IDESSA, BP 621, BOUAKE 01, COTE
D'IVOIRE.
3 IEMVT/CIRAD, 10 Rue P. Curie, 94704 MAISONS-ALFORT Cédex,
FRANCE.
In Oreochromis niloticus, enzyme-histochemical and biochemical studies have detected steroidogenic potentialities of histologically indifferent gonads. During early gonadal ontogenesis, two llB-oxygenated androstenedione derivatives have been specifically identified in testes. The administration, via the alimentation, of these both steroids, adrenosterone and llB-hydroxyandrostenedione, results in high percentages of males. All-male populations are obtained after 21 days treatments with 45-10 µg of 116-hydroxyandrostenedione per gramme of food.
The great lability of early gonadal sex differentiation indicates important regulation potentialities in the production of the natural sex inducers. Temperature is known to play an important part in natural sex inversion for hermaphroditic species, or in the sex determinism of various turtle and crocodile species. More recently, temperature dependent sex determination has been demonstrated in a gonochoric species, Menidia menidia (Conover and Kynard, 1981; Conover, 1984; Conover and Fleisher, 1986; Conover and Heins,
1987a, b).
A very similar thermo-sensitive differentiation has been also revealed in
o.
niloticus: above a critical range of 32-34°C, rearing temperatures produce significantly higher proportions of males than do lower temperatures (27-32°C). The period of thermo-sensitivity is similar in timing and duration to that of the hormone-sensitivity as defined by a 100% efficiency of llB-hydroxyandrostenedione inversion treatment. In the turtle, Emys orbicularis, where sexual differentiation is temperature dependent, temperature influence the steroidogenesis (Desvages et Pieau, 1991); the level of oestrogens could then be involved in gonad differentiation(Dorizzi et al., 1991).
In order to detect a similar mechanism in o.niloticus, differentiating gonads from fry reared at control (27°C) and masculinizing temperatures (36°C) have been incubated with 3
H-Androstenedione as a substrate to investigate the llB-hydroxylase activity.
