A Cost for High Levels of Sperm Competition in Rodents: Increased Sperm DNA Fragmentation

Document Type

Article

Publication Title

Proceedings of the Royal Society B

Publication Date

3-16-2016

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.

Funding Source

This work was supported by a Ramón y Cajal fellowship from the Spanish Ministry of Economy and Competitiveness (RYC-2011-07943) and a Marie Curie Career Integration Grant (PCIG11-GA-2012-321888) to J.d.-T., a fellowship from Campus Científico y Tecnológico de la Energía y el Medioambiente—Universidad de Castilla-La Mancha (CYTEMA-UCLM) to O.G.-Á., a Juan de la Cierva fellowship from the Spanish Ministry of Economy and Competitiveness to M.T (JCI-2011-10381) and grants from the Spanish Ministry of Economy and Competitiveness (CGL2011-26341 to E.R.S.R., CGL2012-37423 to J.d.-T. and AGL2013-48421-R to A.J.S.).

Comments

This article was originally published as delBarco-Trillo Javier, García-Álvarez Olga, Soler Ana Josefa, Tourmente Maximiliano, Garde José Julián and Roldan Eduardo R.S.. (2016) A cost for high levels of sperm competition in rodents: increased sperm DNA fragmentation. Proc. R. Soc. B., (283): 1826. http://doi.org/10.1098/rspb.2015.2708

DOI

https://doi.org/10.1098/rspb.2015.2708

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