title: Sperm chemotaxis promotes individual fertilization success in sea urchins.
abstract: Reproductive success fundamentally shapes an organism's ecology and evolution, and gamete traits mediate fertilization, which is a critical juncture in reproduction. Individual male fertilization success is dependent on the ability of sperm from one male to outcompete the sperm of other males when searching for a conspecific egg. Sperm chemotaxis, the ability of sperm to navigate towards eggs using chemical signals, has been studied for over a century, but such studies have long assumed that this phenomenon improves individual male fitness without explicit evidence to support this claim. Here, we assessed fertilization changes in the presence of a chemoattractant-digesting peptidase and used a microfluidic device coupled with a fertilization assay to determine the effect of sperm chemotaxis on individual male fertilization success in the sea urchin Lytechinus pictus We show that removing chemoattractant from the gametic environment decreases fertilization success. We further found that individual male differences in chemotaxis to a well-defined gradient of attractant correlate with individual male differences in fertilization success. These results demonstrate that sperm chemotaxis is an important contributor to individual reproductive success.
authors.affiliation: University of Washington, Department of Biology, Seattle, WA 98195, USA.
authors.forename: Yasmeen H
authors.initials: YH
authors.lastname: Hussain
authors.affiliation: Tufts University, Department of Mechanical Engineering, Medford, MA 02155, USA.
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Guasto
authors.affiliation: University of California Los Angeles, Department of Ecology and Evolutionary Biology, Los Angeles, CA 90095, USA.
authors.forename: Richard K
authors.initials: RK
authors.lastname: Zimmer
authors.affiliation: ETH Zurich, Department of Civil, Environmental and Geomatic Engineering, Zurich 8093, Switzerland.
authors.forename: Roman
authors.initials: R
authors.lastname: Stocker
authors.affiliation: University of Washington, Department of Biology, Seattle, WA 98195, USA jriffell@uw.edu.
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Riffell
mesh_terms: D000818:Animals; D054443:Cell Migration Assays; D002630:Chemotactic Factors / Q000494:pharmacology; D002633:Chemotaxis / Q000187:drug effects; D002851:Chromatography, High Pressure Liquid; D004527:Egg Proteins / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000187:drug effects / Q000378:metabolism; D047108:Embryonic Development / Q000187:drug effects; D005260:Female; D005306:Fertilization / Q000187:drug effects / Q000502:physiology*; D006162:Guanylate Cyclase / Q000378:metabolism; D021621:Imaging, Three-Dimensional; D008297:Male; D013058:Mass Spectrometry; D044085:Microfluidics; D010196:Pancreatic Elastase / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism; D012015:Reference Standards; D012617:Sea Urchins / Q000187:drug effects / Q000196:embryology / Q000502:physiology*; D013081:Sperm Motility / Q000187:drug effects / Q000502:physiology*; D013094:Spermatozoa / Q000166:cytology* / Q000187:drug effects
chemical_list: D002630:Chemotactic Factors; D004527:Egg Proteins; D011956:Receptors, Cell Surface; D010196:Pancreatic Elastase; D006162:Guanylate Cyclase; C048639:resact protein, sea urchin
keywords: Fertilization ecology; Gamete interactions; Microfluidics; Sperm competition