The effect of eyestalk homogenate on haemolymph vitellogenin levels in the black tiger prawn penaeus monodon

Abstract

Competitive ELISA using a combination of monoclonal antibodies specific to vitellin subunits was used to monitor the fluctuation of haemolymph vitellogenin levels in Penaeus monodon during ovarian development induced by bilateral eyestalk-ablation and to monitor the effect of eyestalk homogenate injection in prawns with developing ovaries. The haemolymph vitellogenin levels were undetectable in the prawn with ovary at the resting stage but elevated sharply when the ovary began to develop, remained high during the ovary developing into the ripe stage, then fell to low levels before spawning and spent stages. The result from injection of eyestalk homogenate into prawns with developing ovaries revealed that haemolymph vitellogenin levels elevated sharply within 2 h, reached the maximal levels and remained high during 4–10 h, then declined slightly at 24 h. This response directly depended on the amount of injected eyestalk homogenate and the response was species specific. The application of eyestalk homogenate from Metapenaeus affinis demonstrated the same stimulatory effect but was less potent, whereas the eyestalk homogenate from Macrobrachium rosenbergii did not cause any changes in haemolymph vitellogenin levels. Therefore, the assay is specific and provides an indicator to monitor the activity of the putative gonad inhibiting hormone by assaying the alteration of vitellogenin levels. © 2004 Taylor & Francis Group, LLC.