Email Print Share

News Release 95-51

Early Events Revealed in the Fertilization of an Egg by a Sperm


August 10, 1995

This material is available primarily for archival purposes. Telephone numbers or other contact information may be out of date; please see current contact information at media contacts.

For the first time, a detailed picture is emerging of the molecular events that occur during fertilization of an egg by a sperm. David Stout, a National Science Foundationsupported researcher at the Scripps Research Institute in La Jolla, California, and Victor Vacquier, a scientist at the University of California, San Diego, present results of their work on this process in the cover article of the September issue of the Journal of Cell Biology.

The organism they have studied is the California red abalone, Haliotis rufescens. In order for a sperm to fuse with an egg, it must first penetrate the egg's extracellular membrane. The abalone sperm uses a protein called lysin to create a hole in this membrane, through which the sperm passes.

Abalone are marine mollusks, with eight species inhabiting the west coast of North America. The species have overlapping breeding seasons and habitats, yet maintain themselves as distinct. The specific structure of lysin is responsible for the species-selective recognition. Stout and Vacquier have determined the three- dimensional molecular structure of lysin. They have shown that two molecules of lysin associate to form a dimer (a protein made up of two polypeptide chains paired together), and have also determined the structure of this dimer. Addition of egg extracellular membrane causes the lysin dimer to dissociate into two monomers. The lysin monomer then penetrates the membrane and creates a hole through which sperm passes. Specific functions can now be assigned to specific features of the lysin molecule that stabilize the dimer and allow the monomer to interact with the extracellular membrane. "These experiments," says Stout, "will allow cell biologists to visualize and understand the fundamentally important biological process of fertilization." The research is funded by NSF's division of molecular and cellular biosciences.

-NSF-

Media Contacts
Cheryl L. Dybas, NSF, (703) 292-8070, email: cdybas@nsf.gov

The U.S. National Science Foundation propels the nation forward by advancing fundamental research in all fields of science and engineering. NSF supports research and people by providing facilities, instruments and funding to support their ingenuity and sustain the U.S. as a global leader in research and innovation. With a fiscal year 2023 budget of $9.5 billion, NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and institutions. Each year, NSF receives more than 40,000 competitive proposals and makes about 11,000 new awards. Those awards include support for cooperative research with industry, Arctic and Antarctic research and operations, and U.S. participation in international scientific efforts.

mail icon Get News Updates by Email 

Connect with us online
NSF website: nsf.gov
NSF News: nsf.gov/news
For News Media: nsf.gov/news/newsroom
Statistics: nsf.gov/statistics/
Awards database: nsf.gov/awardsearch/

Follow us on social
Twitter: twitter.com/NSF
Facebook: facebook.com/US.NSF
Instagram: instagram.com/nsfgov