An abalone egg also uses tryptophan for constructing an embryonic nervous system and building neurotransmitters, as well as for other purposes, Zimmer said.
But the success of the egg's plume in attracting sperm, as well as sperm motility and other elements of the fertilization process, are greatly influenced by ocean flow conditions. Therefore, the biologists analyzed the physics of fluid motion in mediating spermegg interactions.
"The effect is huge, and was previously unsuspected," said Zimmer, who is a member of UCLA's neuroscience program. "The physics of fluid motion has a profound consequence on the ability of sperm to navigate and find an egg, and therefore on fertilization. We have identified the principal mechanisms by which eggs and sperm communicate and interact within an environment that has fluid motion. The method by which sperm in humans search for and find an egg seems to be the same process as in abalone. Similar fluid dynamics operate whether in the turbulent ocean environment or within a mammalian reproductive tract.
"It appears the forces imposed by fluid motion have acted as selective forces in the evolution of the communication system between sperm and egg within abalone. I expect that we will be able to describe the specific environmental conditions within the human reproductive system that will maximize the likelihood of contact between sperm and egg. The physical and chemical environments are actually quite similar."
Zimmer and Riffell, who was formerly a graduate student in Zimmer's lab, conducted fieldwork at San Diego's Point Loma. They employed tiny sensors in a novel way, using Dop
|Contact: Stuart Wolpert|
University of California - Los Angeles