Optimisation of sodium and potassium concentrations and pH in the artificial seminal plasma of common carp Cyprinus carpio L.

Beata Irena Cejko,Zoran Marinović,Radosław Kajetan Kowalski,Jelena Lujić,Timea Kollár,Ákos Horváth,Eszter Kása,Béla Urbányi

doi:10.1007/s10695-018-0491-3

Abstract

The effect of sodium and potassium concentrations as well as optimal pH on the motility of common carp Cyprinus carpio L. sperm during short-term storage in artificial seminal plasma (ASP) was investigated. Sperm was collected from individual males (n = 5) and each sample diluted tenfold (1:9) in ASP (sperm:extender) containing 2 mM CaCl2, 1 mM Mg2SO4 and 20 mM Tris at pH 8.0 and supplemented by the following concentrations of sodium and potassium (mM/mM): 0/150, 20/130, 40/110, 75/75, 110/40, 130/20 and 150/0. The osmolality of all ASP variants was set at 310 mOsm kg−1. Sperm motility was measured using a CASA system during 72 h of storage. Immediately after dilution, sperm motility was high (90%) both in each variant and in the control group (fresh sperm). After 72-h storage, the highest sperm motility was noted in ASP containing 110 mM NaCl and 40 mM KCl. No differences were found in the motility of samples preserved within the pH range of 7.0–9.0. Our data suggest that for the short-term storage of common carp sperm, whereas the pH of the solution does not play a crucial role, a specific potassium concentration of around 40 mM is required.

Highlights

The most important sperm parameter affecting fertilisation capacity in fish is sperm motility
After 72-h storage, the highest motility was observed in sperm samples stored in artificial seminal plasma (ASP) diluted at × 10 (75%), this value differed significantly only from those recorded in the sample diluted × 2 and in the control (Fig. 1)
The highest values of amplitude of lateral head displacement (ALH) were found in fresh sperm at time zero (2.63 μm); these values were significantly different from those recorded for any combination of Na and K in ASP (Table 1; P < 0.05)

Summary

Introduction

The most important sperm parameter affecting fertilisation capacity in fish is sperm motility. It has been postulated that the pH of SP has a significant influence on motility potential in some fish species (Lahnsteiner et al 1996). Cations such as K+ and Na+ play a physical role in maintaining osmotic balance and are important components of a number of enzymes. Cyprinid sperm motility is inhibited by the high osmolality of the seminal plasma, with potassium ions not essential to this process (Perchec-Poupard et al 1997; Cosson 2004). Despite the fact that potassium ions are not essential for the immobilisation of common carp sperm, their concentration in seminal plasma is very high. Márián et al (1997) more recently reported that the pH of common carp seminal plasma is around 8.28

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Conclusion