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In JoVE (1)
Other Publications (1)
Articles by Nathan Tholl in JoVE
Two Types of Assays for Detecting Frog Sperm Chemoattraction
Lindsey A. Burnett1, Nathan Tholl2, Douglas E. Chandler2
1Department of Animal Sciences, University of Illinois, Urbana-Champaign, 2School of Life Sciences, Arizona State University
Eggs and the extracellular coatings around eggs frequently release peptides, proteins and small molecules that communicate with sperm to guide them to the egg thereby promoting fertilization. Using frog sperm we describe and compare two classes of assays used to detect sperm chemoattraction – sperm accumulation assays and sperm tracking assays.
Other articles by Nathan Tholl on PubMed
Swimming of Xenopus Laevis Sperm Exhibits Multiple Gears and Its Duration is Extended by Egg Jelly Constituents
The Biological Bulletin. Jun, 2011 | Pubmed ID: 21712226
The motility of Xenopus sperm is initiated by the osmotic shock experienced when these cells are ejaculated into low-salinity pond water. Motility is brief and is required for the sperm to penetrate the jelly layers and fertilize the egg. In this study we demonstrate that extracts of egg jelly contain factors that extend the period of sperm motility as well as providing a chemoattractant activity as previously reported. Both activities are partially dependent on extracellular calcium. Time-lapse and video microscopy show that after activation of motility the number of motile sperm decreases rapidly, with a half-time of about 2 min. Addition of 10% v/v egg jelly extract ("egg water") increased the number of motile sperm 2-fold over controls at 20 s and about 4- to 10-fold over controls at 10 min after initiation of motility. Extension of motility lifetime was not mediated by a nonspecific protein or by allurin, the egg-water protein that has chemoattractant activity. The helical path of Xenopus sperm exhibited tight coupling between rotational and forward velocities in egg jelly, but coupling changed rapidly from moment to moment in low-salinity buffer. Our observations suggest that jelly-derived factors regulate both the longevity and directionality of sperm propulsion.