Cloning and sequencing of FSH-β and LH-β subunits and changes in their expression during the reproductive cycle in the three-spined stickleback, Gasterosteus aculeatus

Abstract

To achieve a better understanding of the role of gonadotropins (GTHs) in the stickleback we have cloned the full-length cDNAs of the β-subunits of follicle stimulating hormone (FSH) and luteinizing hormone (LH), and analysed the expression during the seasonal cycle. In females, LH-β levels were low during winter and early spring, increased to a peak in late May and declined to low levels again in July. FSH-β expression peaked earlier, in January and declined spring. In males, LH-β expression peaked in May. During June–September, when spermatogenesis occurs, LH-β levels were very low. FSH-β expression peaked earlier, in January, and reached the lowest levels in July. Thus, when spermatogenesis starts, the expression of both GTH-β mRNAs display their lowest levels.