Grant: Discovery Grants Program - Individual

My research on molluscan reproduction, which combines serial ultrathin sectioning with transmission electron microscopy (TEM), is revealing new details of cellular events, such as those occuring at fertilization or during the secretion of substances from cells. Furthermore, Laser Confocal light microscopes, used in conjunction with fluorescent antibodies, are enabling examination of microscopic events in cells, living or dead, with unparalleled clarity. Recent studies in my lab have revealed new information about how animal cells secrete substances from their surfaces. In most snails, waste sperm received by the female are digested by the bursa copulatrix. In littorinids this organ secretes digestive enzymes by an unusual process of macroapocrine secretion. This mechanism was observed for the first time in human males about a decade ago, in the prostate gland and epididymis, where it has been linked to the longevity and egg-binding properties of sperm. I am also interested in microapocrine secretion, which we have found to be responsible for egg hull formation in chitons. This method of secretion, which bi-passes the endomembrane system completely in some cases, is little known and was discovered by us in molluscs. We plan to do 3D reconstruction of apocrine secretion in action for the first time, by using computers to superimpose digital images of serial ultrathin sections taken during this process. Some snails are unusual among animals in that they produce both fertile eusperm and sterile parasperm. The parasperm are not 'mistakes' but rather make up 50% of the ejaculate in some species. Parasperm eliminate the nucleus by programmed nuclear death and yet the cells continue to live and produce complex secretions using stored molecules in the cytoplasm. By losing their nuclei like this, lens cells of the human eye become more transparent and red blood cells improve their oxygen carrying capacity. But what is the function of snail parasperm? We plan to investigate this by isolating unique proteins with electrophoresis, followed by deployment of custom-made antibodies to track their fate in the female and begin to understand their purpose.