Before an egg can be fertilized, it must mature. But the process that triggers oocyte maturation is, thus far, only poorly understood. Insulin-like growth factor (IGF-1), a peptide hormone that is critical during embryogenesis and after, probably plays an important role in mammalian systems in stimulating this process, which is fundamentally the same in all species. Dr. Xingquan Liu concentrates his efforts on determining the mechanism by which IGF-1 transmits signals from outside a cell to inside, causing cellular response.

The effects that IGF-1 asserts on a developing organism have been well established. Dr. Liu's investigation is focussed more specifically on the process by which these effects are asserted. He intends to find out exactly what follows the binding of IGF-1 to a cell's membrane. Knowing what the cascade of response is to this event--which almost certainly involves multiple steps--will, among other things, illuminate our understanding of how IGF-1 controls normal cell growth and development.

Dr. Liu has undertaken to answer this question using frog eggs. These are enormous oocytes, perhaps a thousand times larger than human eggs. That makes it relatively easy to inject them with specific substances, to observe the biological effects following the introduction of those substances, and thereafter, to analyze them biochemically. Thus, the positive or negative effects that result when the normal cascade mediating the reaction of an oocyte to IGF-1 is artificially interrupted or activated can be observed.

The implications of Dr. Liu's line of research are twofold. Establishing precisely what sequence of events follows the bonding of IGF-1 to the frog oocyte's membrane will allow Dr. Liu to take a more directed approach in investigating the stimulation of human oocyte maturation. With the IVF program and ongoing reproductive biology research at the Loeb, Dr. Liu is in a perfect position to pursue this avenue in the future. This will certainly add to the understanding and management of infertility.