Localization of messenger RNAs encoding crustacean hyperglycemic hormone and gonad inhibiting hormone in the X-organ sinus gland complex of the lobster Homarus americanus.

ABSTRACT

The localization of messenger RNAs encoding the crustacean hyperglycemic hormone, involved in regulation of carbohydrate metabolism and the gonad inhibiting hormone, which inhibits vitellogenesis, was studied in the eyestalk of the lobster Homarus americanus using complementary RNA probes for in situ hybridization. For the detection of gonad inhibiting hormone messenger RNA, we cloned and sequenced a partial complementary DNA encoding lobster gonad inhibiting hormone and for crustacean hyperglycemic hormone messenger RNA detection an available complementary DNA was used. This approach reveals that there is a frequent but inconsistent cellular co-localization of the two neurohormones. Furthermore, our data show that male lobsters contain an equal number of neuroendocrine gonad inhibiting hormone cells as female lobsters. An additional study, involving the use of in situ hybridization in combination with immunocytochemistry, shows that the synthetic activity of the crustacean hyperglycemic hormone- and gonad inhibiting hormone-producing cells can be followed at the messenger RNA as well as the protein level. This reveals that when strong immunostaining is present, the messenger RNA staining is usually weak or absent and vice versa. In conclusion, the presence of cells, containing only gonad inhibiting hormone messenger RNA or only crustacean hyperglycemic hormone messenger RNA, indicates that lobster crustacean hyperglycemic hormone and gonad inhibiting hormone originate from two different precursors. Co-localization of the two neurohormone messenger RNAs confirms the co-localization at the peptidergic level found by immunocytochemistry and thus these findings were not due to cross-reactions between the two antisera.(ABSTRACT TRUNCATED AT 250 WORDS)