Vitellogenin levels in the freshwater crayfish Cherax quadricarinatus: preliminary results

FERRÉ, L.E.; MEDESANI, D.A.; GARCÍA, C.F.; RODRÍGUEZ, E.M.

Veracruz

Congreso; World Aquaculture 2009; 2009

World Aquaculture Society

Crustacean vitellogenin (Vg) is a complex lipoprotein taken up by oocytes from the hemolymph during the secondary vitellogenesis. Vg is the precursor of vitellins, essential proteins for developing of embryos after hatching.  Levels of Vg have been measured in several crustacean species and in several tissues, including those suspected to produce Vg (as the hepatopancreas), hemolymph and ovaries. To this respect, however, little is known in crayfish species, particularly in the Australian species  Cherax quadricarinatus  (Decapoda, Parastacidae), widely cultured in several countries around the world. The culture of this species in Argentine has been greatly increased during the last two decades.   The current study was aimed at developing an ELISA assay for detecting Vg in several tissues of   C. quadricarinatus females, to further study the dynamic of its synthesis and uptake during the entire reproductive cycle. After purifying and cleaning-up the Vg from recently eggs hatched by  C. quadricarinatus  females, a primary antibody was obtained from inoculated rabbits. The ELISA was tuned up after assaying different combinations of both Vg and antibody concentrations. After that, five adult females undergoing active vitellogenesis during the pre-reproductive season (June) were used to take samples of hepatopancreas, ovary and hemolymph. These tissues were homogenized in phosphate buffer in a 1:3 proportion (w/v) and then their Vg content was determined by ELISA. No correlation between hepatopancreatic or ovarian Vg levels and hemolymphatic Vg. levels was seen. However, a good correlation in Vg levels between hepatopancreas and ovary was seen, as shown by the Figure. This result is suggesting that at higher Vg synthesis in the hepatopancreas, a higher uptaking of  Vg by the ovaries would take place. This kind of correlation has been observed in several other species of decapod crustaceans, as well as the absent of correlation with circulating levels, since hemomolymph is merely a transit zone for Vg. The effects on Vg levels of several factors (diet, hormones, neuroregulators) are currently under investigation in our laboratory, in order to improve reproduction in captivity and therefore optimizing the production of this relevant species for aquaculture.