Results from several studies suggest that somatolactin (SL), prolactin (PRL), and growth hormone (GH), structurally related proteins, are involved in some aspects of sexual maturation in fishes. To investigate the physiological roles of SL, a model fish species is needed which has been extensively studied and can provide numerous animals and eggs for study. The mummichog, Fundulus heteroclitus, is such a species, and Dr. Safford's preliminary research is designed to begin to develop it as a model for comparing the actions of SL, PRL, and GH. The objectives of the preliminary project are (1) to determine if proteins of the appropriate molecular weights from F. heteroclitus pituitary extracts bind to antibodies against SL, PRL, and GH; (2) to determine if these immunoreactive proteins are found in the appropriate areas within the F. heteroclitus pituitary, and (3) to determine if the F. heteroclitus genome has gene sequences corresponding to conserved regions of fish SL. The experiments for the follow-up project will focus on comparative actions of SL, PRL, and GH on reproductive function in F. heteroclitus, as more studies on SL focus on reproduction than on other processes and there is evidence from the literature that PRL and GH also have reproductive functions. If these three hormones are shown to have some functions in F. heteroclitus, then SL, PRL, and GH will be cloned so that recombinant F. heteroclitus hormones.will be available for more detailed studies in a homologous system.
