Effects of extracellular environment on the osmotic signal transduction involved in activation of motility of carp spermatozoa

Abstract

The mechanism by which a hypo-osmotic shock activates motility of carp spermatozoa was studied. The direct role of osmolality at the axoneme was investigated after demembranation of spermatozoa with Triton X-100 and reactivation in various ionic or anionic solutions containing Mg-ATP: demembranated spermatozoa remain motile in solutions of osmolality up to 550 mOsm kg-1 while non-demembranated spermatozoa are immotile when osmolality rises above 250 mOsm kg-1 with the same salt solutions as well as in non-ionic solutions. Suspension in hypo-osmotic saline solutions triggered the swelling of native carp spermatozoa. No motility or swelling occurred above 200-300 mOsm kg-1 and this osmolality is probably that of the cytosol. The swelling of carp spermatozoa is the result of an entrance of water but this was not affected by pCMBS, an inhibitor of the aquaporin CHIP28, or by various inhibitors of the co-transport of water with ions. Various pharmacological agents that affect the motility of different sperm species had no effect on carp sperm motility when used under similar conditions. However, prolonged exposure to a solution devoid of K+ or Cl- affects the activation of motility in a reversible manner, suggesting that these ions have a role in the perception or transduction of the osmotic signal. Altering the concentration of intracellular second messengers such as Ca2+ and cAMP, and the pH did not affect the motility of carp spermatozoa. However, DMSO at 1-20% (400-3200 mOsm kg-1) affects the motility of carp spermatozoa 3-4 min after mixing. These results show that the activation signal of carp sperm motility differs from that known for spermatozoa of other species of fish such as trout. Our results indicate that the activation mechanism may involve a co-transport of ions or specific 'stretch-activated channels' that are sensitive to osmotic pressure.

Oxidative stress and motility in tench Tinca tinca spermatozoa

“…Such dependence has been shown in the studies of other species (Morisawa et al 1983;Perchec Poupard et al 1997;Alavi et al 2009). Common carp spermatozoa velocity significantly increased in AM from 60 to 140 mOsm/kg AM osmolality, with a progressive decrease when osmolality was increased to 300 mOsm/kg (Perchec Poupard et al 1997). Motility duration of goldfish Carassius auratus spermatozoa at 100 mOsm/kg was significantly higher than at 0 mOsm/kg (Morisawa et al 1983).…”

Biophysics of Fish Sperm Flagellar Movement: Present Knowledge and Original Directions

“…In cyprinids, it was shown that extracellular and intracellular pH, as well as the ionic composition of the swimming media, influences the initiation and duration of sperm motility [59]. As stated above, motility duration of fish spermatozoa is frequently limited by flagellar damages appearing during the motility period, mostly in relation to osmotic stress imposed at motility initiation [60].…”

“…Therefore, unrelated variables were designed to describe specifically the flagellar beating through their wave properties [89]. Initial studies developed on invertebrate's sperm flagella [90] were applied to flagella of marine fish spermatozoa [14,91,92] such as turbot [70], sea bass [69], cod and hake [64], as well as to freshwater species such as trout [78], salmon [93], carp [60], sturgeon [3] and pike [11]. Some of the flagellar wave parameters play a critical role for the displacement efficiency of the whole sperm cell and control the forward velocity of translation, for example, the amplitude and the length of each flagellar wave, the number of bends, the curvature of the bend pattern, the wave velocity and the flagellar beat frequency.…”

“…-induced asymmetry also occurs in freshwater species, such as trout [115] and carp [60], where due to increased Ca 2+ concentration spermatozoa describe circular trajectories, which become tighter with time elapsed after activation. Nevertheless, it was shown that asymmetry of the flagellar waveform can appear in the absence of any cell signaling change or flagellar heterogeneity.…”

Inhibitory effect of K+ and Ca2+ concentrations, pH, and osmolality of activation solution on motility of shabut (Barbus grypus Heckel 1843) spermatozoa

“…The external pH probably influences the intracellular proton concentration, which subsequently affects membrane potential as well as motility behavior (6). In contrast, pH has relatively little impact on carp spermatozoa motility (7), except at an extreme pH via a Na + /H + exchanger (5). Moreover, carp spermatozoa motility can be initiated in a medium with a pH between 6.0 and 9.0 (8).…”