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Comp Biochem Physiol A Mol Integr Physiol. 2018 Apr;218:35-45. doi: 10.1016/j.cbpa.2018.01.006. Epub 2018 Jan 31.

Activation of free sperm and dissociation of sperm bundles (spermatozeugmata) of an endangered viviparous fish, Xenotoca eiseni.

Author information

1
Aquatic Germplasm and Genetic Resources Center, School of Renewable Natural Resources, Louisiana State University Agricultural Center, Baton Rouge, LA, USA.
2
School of Forest Resources and Conservation, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL, USA.
3
Aquatic Germplasm and Genetic Resources Center, School of Renewable Natural Resources, Louisiana State University Agricultural Center, Baton Rouge, LA, USA. Electronic address: ttiersch@agcenter.lsu.edu.

Abstract

Knowledge of sperm motility activation for viviparous fishes has been limited to study of several species in Poeciliidae, and the dissociation of sperm bundles is even less understood. The goal of this study was to use the endangered Redtail Splitfin (Xenotoca eiseni) as a model to investigate the activation of sperm from viviparous fishes by study of free sperm and spermatozeugmata (unencapsulated sperm bundles). The specific objectives were to evaluate the effects of: (1) osmotic pressure and refrigerated storage (4 °C) on activation of free sperm, (2) osmotic pressure, ions, and pH on dissociation of spermatozeugmata, and (3) CaCl2 concentration and pH on sperm membrane integrity. Free sperm were activated in Ca2+-free Hanks' balanced salt solution at 81-516 mOsmol/kg. The highest motility (19 ± 6%) was at 305 mOsmol/kg and swim remained for 84 h. Glucose (300-700 mOsmol/kg), NaCl (50-600 mOsmol/kg), and KCl, MgCl2, and MnCl2 at 5-160 mM activated sperm within spermatozeugmata, but did not dissociate spermatozeugmata. CaCl2 at 5-160 mM dissociated spermatozeugmata within 10 min. Solutions of NaCl-NaOH at pH 11.6 to 12.4 dissociated spermatozeugmata within 1 min. The percentage of viable cells had no significant differences (P = 0.2033) among different concentrations of CaCl2, but it was lower (P < 0.0001) at pH 12.5 than at pH between 7.0 and 12.0. Overall, this study provided a foundation for quality evaluation of sperm and spermatozeugmata from livebearing fishes, and for development of germplasm repositories for imperiled goodeids.

KEYWORDS:

Ca(2+); Endangered species; Fish conservation; Goodeids; Sperm activation; Sperm bundles; Sperm cryopreservation; Viviparous fish; Xenotoca eiseni; pH

PMID:
29371117
PMCID:
PMC5834398
DOI:
10.1016/j.cbpa.2018.01.006
[Indexed for MEDLINE]
Free PMC Article

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