Plant & Animal Genomes XI Conference Plant & Animal Genomes XI ConferenceJanuary 11-15, 2003
Town & Country Convention Center
San Diego, CA
Workshop: Aquaculture
Two proteins and their respective cDNAs have been identified and sequenced so far from the marine shrimp (Penaeus semisulcatus) ovary. These are the vitellogenin/vitellin (VTG/VT), the main protein component of the egg yolk, and the shrimp ovarian peritrophin (SOP), a component of the cortical rods and the jelly layer, surrounding eggs immediately after spawning. Differences were found in the temporal pattern of VTG and SOP mRNA expression in the ovary and hepatopancreas, during the ovarian developmental cycle. While SOP mRNA was detected at all stages of oocyte development, with relatively higher abundance during previtellogenic stages, the expression of VTG/VT was very low during post-molt previtellogenic stages and increased during vitellogenesis. Eyestalk ablation is commonly used for triggering ovarian development. Therefore, studies were initiated to reveal the mode of regulation of protein synthesis and gene expression of VTG and SOP. Crude sinus gland extracts (SGE) and CHH (crustacean hyperglycaemic hormones) peptides contained in the eyestalks were found to reduce protein (including VT and SOP) and mRNA synthesis in in vitro incubated ovarian explants. SGE, however, did not affect the steady state levels of SOP transcripts at any stage of ovarian development, suggesting that regulation of SOP synthesis is at the posttranscriptional level. The effect of SGE and CHH peptides on expression of VTG mRNA, is under investigation. Future studies should reveal the identity of ovarian mRNAs affected by SGE and CHH peptides. These studies are of additional interest, as higher CHH plasma levels were reported to be associated with an infection or disease.