Induced reproduction of cultured species helps to produce quantity and quality seed an important component for upright yield in crustacean aquaculture.The present study was aimed to investigate the role of arachidonic acid in the regulation of ovarian development in the freshwater crab, Oziothelphusa senex senex.Injection of AA significantly (p<0.001)increased the ovarian index, oocyte diameter and ovarian vitellogenin levels.Injection of COX inhibitors such as indomethacin and aspirin alone, and in combination with AA resulted in significant (p<0.001)reduction in ovarian index, oocyte diameter and ovarian vitellogenin levels in crabs.The results of the present study provide evidence that arachidonic acid and COX inhibitors involved in the regulation of female reproduction in the freshwater crab, Oziothelphusa senex senex.
AbstractAdministration of eyestalk extracts of fresh water crab and marine prawn caused an increase in haemolymph sugar level and tissue phosphorylase activity in the slug. Tissue glycogen and total carbohydrates registered a significant decrease which indicated the source of hyperglycemia was the tissue carbohydrates. The results prove that crustacean hyperglycemic hormone exerts influence on non-crustacean species.
Various methods for the quantification of stress in crustaceans have been developed in our laboratory. An ELISA was developed for the crustacean hyperglycemic hormone (CHH) from the lobster, Homarus americanus. It is sensitive to as little as 0.2 fmol of peptide. Increases in hemolymph CHH were observed following emersion. Significant levels of hemolymph CHH were also measured in lobsters that had been eyestalk-ablated. It was observed that these animals continued to produce CHH, even though the heretofore only known source of CHH had been removed. Portions of the central nervous system, from both intact and eyestalk-ablated lobsters were observed to contain significant amounts of CHH. A cDNA library was constructed from eyestalk neural tissue of H. americanus. With the use of PCR, a 171 bp probe was isolated and purified. This probe was labeled and used to examine levels of CHH expression in the central nervous system (CNS) and in eyestalk neural tissue at different periods of the lobster molt cycle. CHH mRNA is present throughout the CNS. In the eyestalk, it is undetectable in postmolt, low in intermolt, and high in premolt. Stress proteins, also known as heat shock proteins (HSPs), are a highly conserved class of proteins which show elevated transcription during periods of stress in organisms as phylogenetically divergent as bacteria and humans. Using RT-PCR, we have partially cloned the lobster HSP90 gene. A 380 bp probe was 32P-labeled and hybridized with northern blots of midgut gland total RNA from heat-shocked lobsters. A 2 hr acute heat shock from 15%C (ambient water temperature) to 28%C resulted in a 6.0-fold induction of HSP90 after 6 hr of recovery at 15%C. A northern analysis of RNA isolated from the midgut glands of lobsters injected with 10 μg of the molting hormone 20-hydroxyecdysone displayed a 2.1-fold induction of HSP90 RNA 48 hr postinjection.
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