A cost for high levels of sperm competition in rodents: increased sperm DNA fragmentation |
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Authors: | Javier delBarco-Trillo Olga García-álvarez Ana Josefa Soler Maximiliano Tourmente José Julián Garde Eduardo R. S. Roldan |
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Affiliation: | 1.Reproductive Ecology and Biology Group, Museo Nacional de Ciencias Naturales (CSIC), Madrid 28006, Spain;2.SaBio IREC (CSIC-UCLM-JCCM), Albacete 02071, Spain;3.School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool L3 3AF, UK |
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Abstract: | Sperm competition, a prevalent evolutionary process in which the spermatozoa of two or more males compete for the fertilization of the same ovum, leads to morphological and physiological adaptations, including increases in energetic metabolism that may serve to propel sperm faster but that may have negative effects on DNA integrity. Sperm DNA damage is associated with reduced rates of fertilization, embryo and fetal loss, offspring mortality, and mutations leading to genetic disease. We tested whether high levels of sperm competition affect sperm DNA integrity. We evaluated sperm DNA integrity in 18 species of rodents that differ in their levels of sperm competition using the sperm chromatin structure assay. DNA integrity was assessed upon sperm collection, in response to incubation under capacitating or non-capacitating conditions, and after exposure to physical and chemical stressors. Sperm DNA was very resistant to physical and chemical stressors, whereas incubation in non-capacitating and capacitating conditions resulted in only a small increase in sperm DNA damage. Importantly, levels of sperm competition were positively associated with sperm DNA fragmentation across rodent species. This is the first evidence showing that high levels of sperm competition lead to an important cost in the form of increased sperm DNA damage. |
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Keywords: | sperm competition rodents sperm DNA fragmentation capacitation oxidative stress sperm chromatin structure assay |
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