REPRODUCTIVE BIOLOGY AND CELL BIOLOGY
The production of eggs by the adult involves a long and complex sequence of interactions between the somatic tissues of the adult and the growing oocyte. One aspect of our work is directed towards understanding the hormonal signals, cellular interactions, and nutritional requirements that impact on oocytes as they pass from one stage of growth to another. Fish species in particular display a wide variety of adaptive modes of reproduction. Therefore, we are primarily identifying and using such animals as a rich experimental resource to study stage-specific events of oocyte growth within the animal.
At the same time, oocytes are removed from the animal (amphibians, fish) and cultured to study the capacity of the oocyte to grow in the absence or presence of external cues. Stage-specific events, such as packaging of secretion granules, endocytosis of external protein, proteolytic processing within the oocyte, and oocyte hydration as a response to added steroids, are also being examined in detail, since the oocyte in culture serves as a large, single-cell model for each of these cellular processes that are also important to most other somatic cells.
Finally, the most prominent feature of nonmammalian eggs is the presence of enormous quantities of yolk. We have been engaged in a long-term project to define the macromolecular characteristic and comparative biochemistry of the lipoproteins and phosphoproteins present in vertebrate yolk. Microheterogeneity related both to multi-gene families and to heterogenous processing is one interest; proteolytic conversion of yolk proteins during various stages of oocyte growth is another.
Lin, Y-W.P., B. A. Rupnow, D. A. Price, R. M. Greenberg, and R. A. Wallace. 1992. Fundulus heteroclitus gonadotropins 3. Cloning and sequencing of gonadotropic hormone (GTH) I and II -subunits using the polymerase chain reaction. Mol. Cell. Endocrinol. 85:127-139.
Petrino, T. R., Y-W. P. Lin, and R. A. Wallace. 1992. Steroidogenesis in Fundulus heteroclitus IV. Dichotomous effects of a phorbol ester on ovarian steroid production and oocyte maturation. J. Exp. Zool. 263:254-264.
Wallace, R. A., M. S. Greeley, Jr., and R. McPherson. 1992. Analytical and experimental studies on the relationship between Na+, K+, and water uptake during volume increases associated with Fundulus oocyte maturation in vitro. J. Comp. Physiol. B 162:241-248.