Composition of ovarian fluid in endangered Caspian brown trout, Salmo trutta caspius, and its effects on spermatozoa motility and fertilizing ability compared to freshwater and a saline medium

Abstract

In this study, ovarian fluid composition and its effects on the motility and fertilizing ability of sperm were studied in endangered Caspian brown trout, Salmo trutta caspius, and were compared with a saline activation medium (125 mM NaCl, 30 mM Glycine, 20 mM Tris-HCl, pH = 9.0) and freshwater as the control. The ovarian fluid was composed of sodium 164.4 +/- 4.4 mM l(-1), potassium 1.8 +/- 0.1 mM l(-1), calcium 0.6 +/- 0.1 mM l(-1), magnesium 0.4 +/- 0.02 mM l(-1), chloride 127.4 +/- 5.9 mM l(-1), total protein 389.5 +/- 89.6 mg 100 ml(-1), cholesterol 9.3 +/- 1.2 mg dl(-1), and glucose 3.3 +/- 0.2 mM l(-1). The percentage of motile spermatozoa and the duration of sperm motility were significantly higher in ovarian fluid (62 +/- 3%, 74.6 +/- 0.8 s) than freshwater (35 +/- 4%, 44 +/- 1 s), but they did not differ significantly from saline medium (56 +/- 3%, 74.3 +/- 0.7 s) (P > 0.05). Higher eyeing rates were observed after the activation of sperm in ovarian fluid and saline solution than freshwater when 35,000 or 350,000 spermatozoa per egg were added into the activation media. However, no significant differences were observed at higher concentrations of spermatozoa per egg (730,000) (P > 0.05). Also, this study showed that the ovarian fluid composition can be considered as a species-specific character among salmonid fishes. As a conclusion, the results of this study recommend the use of ovarian fluid or the saline solution as an activation medium in the artificial reproduction of Caspian brown trout.

Wild Atlantic cod sperm motility is negatively affected by ovarian fluid of farmed females

“…Nevertheless, we observed that the sperm fertilization capacity was negatively affected by the farmed females' ovarian fluid but not by the replacement of a saline solution (Cortland solution). Similar results were observed in S. trutta caspius (Hatef et al 2009) and in G. aculeatus (Elofsson et al 2006), where beneficial effects on sperm motility and fertilizing capacity occurred in the presence of both the ovarian fluid and a specific saline solution mimicking its ionic composition. These results provide some evidence that the ionic composition of the ovarian fluid is, at least partly, responsible for its effects on sperm fertilization capacity.…”

“…According to Wojtczak et al (2007), the pH of the ovarian fluid is a determinant of sperm motility in Oncorhynchus mykiss. The ion composition of ovarian fluid is also believed to influence sperm motility (Lahnsteiner 2002, Elofsson et al 2006, Hatef et al 2009, Rosengrave et al 2009b, Kanuga et al 2012, which in our cod was comparatively closer to that of marine G. aculeatus (Elofsson et al 2006) than to salmonids (Lahnsteiner et al 1995, Hatef et al 2009, Rosengrave et al 2009b. This is likely related to the higher ionic concentration of the marine environment.…”

Ovarian fluid impacts flagellar beating and biomechanical metrics of sperm between alternative reproductive tactics

“…Our calculation of hydrodynamic output also clearly shows that when ovarian fluid is incorporated into the swimming medium, the sperm require further power output for movement, which can probably be attributed to increased viscosity (Turner and Montgomerie, 2002) and/or alterations in biochemical composition (i.e. ions, proteins as discussed below) of the activation media (see Wojtczak et al, 2007;Hatef et al, 2009;Rosengrave et al, 2009b, among others). The main protein composition of salmon ovarian fluid was investigated by Johnson et al (2014): their proteomic analysis led to identification of 174 proteins of interest, among which 26 are either involved in the hypoxia pathway or are chemical stimuli, some of the latter probably being related to control of sperm function near the egg.…”

Proteomic Analysis of Chinook Salmon (Oncorhynchus tshawytscha) Ovarian Fluid

“…Studies in a variety of species indicate that ovarian fluid is likely to have several important biological functions, most notably in reproduction [1], [10], [12]–[16]. For instance, when rainbow trout ( Oncorhynchus mykiss ) ovulated eggs were stored in ovarian fluid for three days, they maintained fertility and developmental competence in contrast to those stored in trout artificial medium [10], [17].…”

“…Ovarian fluid in Arctic charr ( Salvelinus alpinus ), chinook salmon, rainbow trout, lake trout ( Salvelinus namaycush ) and brown trout ( Salmo trutta ) is known to have an activating effect on sperm swimming speed, percent motility, and duration of sperm motility [12]–[16], [20]–[24] compared to activation in fresh water [2], [7], [11], [12], [25] or to very dilute ovarian fluid [26], [27]. Though even 10% ovarian fluid has been shown to result in a 70% increase in sperm motility in lake trout [22].…”