In vitro effect of juvenoids and steroids on the ovarian growth of Cherax quadricarinatus (Decapoda, Parastacidae).

MEDESANI, D.A.; GRODZIELSKI, M.; RODRÍGUEZ, E.M.

Veracruz

Congreso; World Aquaculture 2009; 2009

World Aquaculture Society

The Australian freshwater crayfish, Cherax quadricarinatus, has been intensively cultured in Argentine farmers during the last two decades. However, since Argentina has a marginal climate for the growth-out of this tropical species, several procedures of reproductive management are under research in our laboratory, mainly aimed at shifting the normal reproductive season of the species (spring and summer) to autumn and summer, in order to transfer the juveniles to the external ponds for growth-out at the beginning of the spring (i.e., growing of juveniles would occur during the more favorable months of the year). We have previously assayed in several crustacean species (including C. quadricarinatus) the effects of some neuroregulators and hormones on the ovarian growth, by means of both in vivo and in vitro assays. In the current study, we have assayed the in vitro effect on the ovary of a very well known juvenile hormone of crustaceans, methyl farnesoate, as well as the effect of the steroid hormone estradiol (as 17¥â-estradiol). The assays were made using crayfish females out of their normal reproductive season (July). The in vitro procedure comprised a short (24 h) incubation of small ovarian pieces (5 mm long) with several doses of methyl farnesoate or estradiol (0,15; 1,5; 15 ¥ìM for both hormones). A suitable incubation medium was used (M199 Sigma) in 2-mL vials, added with an aliquot of tritiated leucine (3 uCi). A temperature of 28¨¬C and a controlled atmosphere of CO2 (5%) were maintained throughout. At the end of the incubation period, each ovarian piece was weighed and homogenized in 10% cold trichloroacetic acid, filtered, and the radioactivity content in the acid-precipitable fraction was determined by means of a scintillation counter. The Figures show the obtained results. No significant differences (p>0.05) were observed in the incorporation of the aminoacid leucine to proteins, by effect of estradiol. As for methyl farnesoate, the highest dose employed caused a significant (p<0.05) increased in the leucine incorporation to proteins (mainly vitelins). This result was similar to those we have previously obtained with Procambarus clarkii, stressing the relevance of methyl farnesoate to induce ovarian activity even out of the reproductive season.