Expression of the crustacean hyperglycaemic hormones and the gonad-inhibiting hormone during the reproductive cycle of the female American lobster Homarus americanus

Abstract

Crustacean reproduction is regulated by a complex chain of hormonal interactions in which the crustacean hyperglycaemic hormones A and B (CHH-A and CHH-B) and the gonad-inhibiting hormone (GIH) play a primary role. These neurohormones are produced in the same neuroendocrine cells of the X-organ sinus gland complex, situated in the eyestalks of the American lobster, Homarus americanus. In order to obtain more information on the synthesis, storage, release and function of these three neuropeptides during the reproductive cycle, we studied the levels of their mRNAs in the X-organ, their peptide storage in the sinus gland and their concentration in the haemolymph at different stages of the female reproductive cycle. A high CHH-A mRNA level was found only in the previtellogenic stage, while elevated mRNA levels were determined for CHH-B in the mature as well as the previtellogenic stage. High CHH storage levels in the sinus gland were found during previtellogenesis. The total amount of CHH (CHH-A plus -B) in the haemolymph was significantly higher during maturation. A low level of GIH mRNA in the X-organ and a low amount of the GIH I isoform in the sinus gland were found only in the immature stage. In contrast, GIH haemolymph levels were high during the immature and previtellogenic stages. We conclude that CHH-A and -B are involved in triggering the onset of vitellogenesis and that CHH-B in particular is responsible for stimulating oocyte maturation before spawning, while GIH prevents the start of vitellogenesis in the ovary. Moreover, our results show that the balance between the haemolymph levels of the CHHs and GIH may tune the synchronization of reproduction and molting during the biannual reproductive cycle of the American lobster.

Crustacean Molting: Regulation and Effects of Environmental Toxicants

“…Thus similarity between GIH and MIH support the hypothesis phenomena of involvement of VIH in molting. GIH might have a molt-inhibiting function because female lobsters molt only after hatching of their larvae when the CHH and GIH hemolymph levels are low in H. americanus [41].…”

Cloning of Two Crustacean Hyperglycemic Hormone Isoforms in Freshwater Giant Prawn ( Macrobrachium rosenbergii ): Evidence of Alternative Splicing

“…Two CHH isoforms of the American lobster Homarus americanus, CHH A and CHH B, were markedly elevated in hemolymph soon after molting and upon the onset of vitellogenesis (de Kleijn et al, 1998). CHH-B was noted especially for its potency to stimulate oocyte growth (Tensen et al, 1989).…”

New insights into evolution of crustacean hyperglycaemic hormone in decapods – first characterization in Anomura

“…MIHs have been described in all decapod groups investigated, except the Homarida, in which a CHH isoform has a moult-inhibiting function [15]. In this taxon, another type II peptide has been described: the VIH, which controls ovarian development by inhibiting vitellogenesis in female lobsters [10]. This function seems to be performed by CHH in other decapods, as mentioned above.…”

“…However, a number of experimental studies have since demonstrated that CHH is a pleiotropic hormone, but its precise physiological roles are far from clear and vary greatly according to species. For example, CHH is involved in the control of female reproduction, either positively in the lobster Homarus americanus [10] or negatively in the green tiger prawn Penaeus semisulcatus [11]. CHH inhibits the synthesis of methyl farnesoate -a juvenile hormone-like compound that mainly acts on gonad growth -in the spider crab Libinia emarginata, acts on lipid metabolism and is implicated in osmoregulation in several decapod species [12].…”