This study aims at immunochemical characterization of plasma vitellogenin (VTG), development of an heterlogous VTG ELISA and to relate seasonal variation in plasma VTG and estradiol-17β (E2) levels with ovarian growth (gonadosomatic index, GSI) in
(McClelland, 1842), a rare hill-stream catfish endemic to North East India... [details of abstract omitted here]... Congruent with gradual increase in plasma E2, ovarian weight and appearance of vitellogenic and yolky oocytes, VTG level in circulation increased sharply in May–June, reaching the peak value in July, dropped sharply during August–September and was undetected or negligible in amount during December allowing identification of the ripening, the pre-spawning, the spawning and the quiescent phases respectively.
From the authors' discussion:
Although in the Indian subcontinent, a vast majority of the fresh water fishes breed during the monsoon season when rainfall is heaviest, reproductive parameters of O. longicaudata have not been studied before... Accumulating evidences have established that kinetics of ovarian growth correlates with oocyte morphology, profile of plasma sex steroids and plasma VTG in reproductively active female teleosts... Interestingly, sharp decrease in GSI, plasma VTG and E2 levels, sign of oocytes undergoing maturation and hydration... and elevated fecundity during August–September indicate the end of vitellogenesis and onset of spawning season.
