Dr. Victor D Vacquier
I will not list all the new facts we discovered about fertilization in marine invertebrates. I believe that one major conceptual contribution my lab made was the realization that most genes coding for proteins involved in sexual reproduction evolve very rapidly, in fact, as rapidly as immunological genes. This is true for invertebrates and vertebrates (Moy, Springer, Adams, Swanson, & Vacquier, 2008; Swanson & Vacquier, 2002; Vacquier, 1998). We first discovered this when we found that species comparisons showed strong “positive selection” in abalone sperm lysin (Lee, Tatsuya, & Vacquier, 1995). With abalone, the two sperm acrosomal genes (bindin and 18 K) are evolving many times faster than the mitochondrial genomes (Metz, Robles-Sikisaki, & Vacquier, 1998). The selective pressure could be to attempt to ensure monospermic fertilization. Sperm competition is always selecting for the fastest sperm to fuse with the egg. The hypothesis posits that those eggs that slow sperm-egg fusion have altered sperm receptors and have a better chance to be monospermic and become embryos and later adults. Sperm are selected for on the basis of how well they match the changing egg receptor. Thus, there is a continuous race between the gametes, egg receptors for sperm changing to attempt to ensure monospermy and sperm always trying to match the ever-changing receptor. We know that when a favorable abalone lysin sequence is attained it sweeps the entire population of the species, whereas an intron of a G-protein shows ~ 5% nucleotide variation among individuals of that same species (Metz et al., 1998).
Lab MembershipsHamdoun (Principal Investigator/Director)