Abstract
Secretion of ecdysteroid molting hormones by crustacean Y-organs is suppressed by molt-inhibiting hormone (MIH). The suppressive effect of MIH on ecdysteroidogenesis is mediated by one or more cyclic nucleotide second messengers. In addition, existing data indicate that ecdysteroidogenesis is positively regulated (stimulated) by intracellular Ca++. Despite the apparent critical role of calcium in regulating ecdysteroidogenesis, the level of Ca++ in Y-organ cells has not been previously measured during a natural molting cycle for any crustacean species. In studies reported here, a fluorescent calcium indicator (Fluo-4) was used to measure Ca++ levels in Y-organs during a molting cycle of the blue crab, Callinectes sapidus. Mean calcium fluorescence increased 5.8-fold between intermolt (C4) and stage D3 of premolt, and then dropped abruptly, reaching a level in postmolt (A) that was not significantly different from that in intermolt (P>0.05). The level of ecdysteroids in hemolymph of Y-organ donor crabs (measured by radioimmunoassay) showed an overall pattern similar to that observed for calcium fluorescence, rising from 2.9ng/mL in intermolt to 357.1ng/mL in D3 (P<0.05), and then dropping to 55.3ng/mL in D4 (P<0.05). The combined results are consistent with the hypothesis that ecdysteroidogenesis is stimulated by an increase in intracellular Ca++.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
More From: Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.