title: Differences in the fatty-acid composition of rodent spermatozoa are associated to levels of sperm competition.
abstract: Sperm competition is a prevalent phenomenon that drives the evolution of sperm function. High levels of sperm competition lead to increased metabolism to fuel higher sperm velocities. This enhanced metabolism can result in oxidative damage (including lipid peroxidation) and damage to the membrane. We hypothesized that in those species experiencing high levels of sperm competition there are changes in the fatty-acid composition of the sperm membrane that makes the membrane more resistant to oxidative damage. Given that polyunsaturated fatty acids (PUFAs) are the most prone to lipid peroxidation, we predicted that higher sperm competition leads to a reduction in the proportion of sperm PUFAs. In contrast, we predicted that levels of sperm competition should not affect the proportion of PUFAs in somatic cells. To test these predictions, we quantified the fatty-acid composition of sperm, testis and liver cells in four mouse species (genus Mus) that differ in their levels of sperm competition. Fatty-acid composition in testis and liver cells was not associated to sperm competition levels. However, in sperm cells, as predicted, an increase in sperm competition levels was associated with an increase in the proportion of saturated fatty-acids (the most resistant to lipid peroxidation) and by a concomitant decrease in the proportion of PUFAs. Two particular fatty acids were most responsible for this pattern (arachidonic acid and palmitic acid). Our findings thus indicate that sperm competition has a pervasive influence in the composition of sperm cells that ultimately may have important effects in sperm function.
authors: Reproductive Ecology and Biology Group, Museo Nacional de Ciencias Naturales, CSIC, 28006 Madrid, Spain Present address: School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool L3 5UA, UK. delbarcotrillo@gmail.com.
authors: Javier
authors: J
authors: delBarco-Trillo
authors: Wildlife Toxicology Group, Instituto de Investigación en Recursos Cinegéticos, CSIC-UCLM-JCCM, 13071 Ciudad Real, Spain.
authors: Rafael
authors: R
authors: Mateo
authors: Reproductive Ecology and Biology Group, Museo Nacional de Ciencias Naturales, CSIC, 28006 Madrid, Spain.
authors: Eduardo R S
authors: ER
authors: Roldan
keywords: Arachidonic acid; Lipid peroxidation; PUFA; Polyunsaturated fatty acids; Sperm competition; Sperm membrane