title: Electroejaculation and semen buffer evaluation in the microbat Carollia perspicillata.
abstract: Scientific interests and conservation needs currently stress the necessity to better understanding bat reproductive biology. In this study, we present the first, safe, inexpensive, and reliable method to obtain sperm from a microbat species (Carollia perspicillata) by electroejaculation. This method revealed to be highly efficient (100% success rate). We obtained ejaculates composed of two characteristically different fractions. We compared three buffers and recommend using an Earle's balanced salt solution as a semen extender. Earle's balanced salt solution provided significant repeatable measure of swimming ability (intraclass correlation coefficient: 0.74, P < 0.01) and proportion of motile sperms (intraclass correlation coefficient: 0.08, P = 0.01) and allowed sperm to maintain optimal swimming capacity over time. None of the buffers could dissolve all the coagulated sperm. Although the trypsin buffer freed a larger fraction of spermatozoa in the ejaculate, it impaired swimming ability without improving motility, viability, and stamina. We thus argue that the sperm population analyzed with Earle's balanced salt solution is a representative of the ejaculate. Finally, we found that the mean sperm velocity of C perspicillata (78.8 μm/s) is lower than that predicted by regressing sperm velocity on relative testes mass, a proxy of sperm competition. The question as to whether C perspicillata is an outsider for sperm velocity, or whether bats evolved yet another unique mechanism to cope with sperm competition deserves more investigations.
authors.affiliation: Evolutionary Ecology Division, Institute of Ecology and Evolution, University of Bern, Bern, Switzerland. Electronic address: nicolas.fasel@iee.unibe.ch.
authors.forename: Nicolas Jean
authors.initials: NJ
authors.lastname: Fasel
authors.affiliation: Evolutionary Ecophysiology Lab, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Helfenstein
authors.affiliation: Université de Lyon, VetAgro Sup, UPSP 2011-03-101 ICE/CRB-ANIM ANR-11-INBS-0003, Marcy-l'Étoile, France.
authors.forename: Samuel
authors.initials: S
authors.lastname: Buff
authors.affiliation: Evolutionary Ecology Division, Institute of Ecology and Evolution, University of Bern, Bern, Switzerland.
authors.forename: Heinz
authors.initials: H
authors.lastname: Richner
mesh_terms: D000818:Animals; D002685:Chiroptera / Q000502:physiology*; D004542:Ejaculation / Q000502:physiology*; D004558:Electric Stimulation / Q000379:methods*; D008297:Male; D012661:Semen / Q000502:physiology*; D012662:Semen Preservation / Q000662:veterinary*; D013048:Specimen Handling / Q000379:methods; D013081:Sperm Motility / Q000502:physiology
keywords: Electroejaculation; Microchiroptera; Semen extender; Sperm competition; Sperm mobility