Motility activation and metabolism characteristics of spermatozoa of the black-lip-pearl oyster Pinctada margaritifera var: cumingii (Jameson, 1901)

Abstract

Motility of Pinctada margaritifera (Linnaeus, 1758); var: cumingii (Jameson, 1901) (P. margaritifera) spermatozoa collected from gonads are not immediately activated at spawning in seawater (SW) but motility occurs when spermatozoa are transferred into alkaline seawater (pH ranging from 9.0 to 11.4). This motility-activating effect of alkaline pH is reversed when pH is shifted back to more acidic values. In both cases, activity of sperm (% motile cells) increases gradually after alkaline pH activation then lasts for several minutes. The characteristics of these fully motile spermatozoa are described in details at the level of flagella: the wave amplitude and wave-length range 5 to 6 μm and 15 μm respectively, while the flagellar beat frequency is approximately 49 Hz. The velocity of sperm displacement is from 220 to 230 μm/sec. The general swimming pattern is almost circular: the head trajectories describe portions of circles intercalated with small linear segments. Spermatozoa saved in natural seawater at 4°C retain potent motility for several days and can be subsequently activated by alkaline seawater. Respiration and ATP concentration were measured in 3 conditions: regular seawater (pH 7.8), artificial diluent (pH 8.2), and alkaline Tris-buffered seawater (pH 10.5). Results show that sperm respiration rates are higher whereas ATP levels are lower in the latter two media.

Effect of sampling location, release technique and time after activation on the movement characteristics of scallop (Pecten maximus) sperm

“…The mean intracellular ATP content of scallop sperm is high compared to that measured in different mollusk species (from 4 to 45 nmol × 10 −9 spermatozoa; Suquet et al 2010). However, an even higher ATP content was assessed in black-lip-pearl oysters: 700 nmol × 10 −9 spermatozoa (Demoy-Schneider et al 2012).…”

“…Compared to scallop, lower values of VAP were reported in blue mussels (Mytilus edulis): 103 ± 2 µm s −1 (Jha et al 2007) or Pacific oyster: 72 ± 14 µm s −1 (Faure 1996). On the other hand, a higher swimming speed was assessed in black-lip-pearl oysters: 221 ± 12 µm s −1 (Demoy-Schneider et al 2012). The mean intracellular ATP content of scallop sperm is high compared to that measured in different mollusk species (from 4 to 45 nmol × 10 −9 spermatozoa; Suquet et al 2010).…”

“…This phenomenon was also reported in aquatic species such as rainbow trout (Oncorhynchuss mykiss; Morisawa and Morisawa 1986) and turbot (Psetta maxima; Dreanno 1998): in both species, spermatozoa acquire their potential for motility in the genital tract. In mollusk bivalves, spermatozoa collected from the testis of pearl oysters (Pinctada fucata martensii) cannot be activated after dilution in seawater while sperm motility was activated in alkaline a Corresponding author: marc.suquet@ifremer.fr seawater buffered at pH 9.4, suggesting an in vitro maturation of testicular spermatozoa (Ohta et al 2007;Demoy-Schneider et al 2012). The flagellar beat frequency was lower for Pacific oyster (Crassostrea gigas) sperm collected by testicular stripping compared to values recorded for sperm released after transfer through the genital ducts, following serotonin (5-hydroxytryptamine) injection or thermal shock (Cosson et al 2008a).…”

Roles of extracellular ions and pH in 5-HT-induced sperm motility in marine bivalve

“…However, [pH] e is not a key determinant to maintain sperm in the quiescent state in the testis because i) the [pH] e at which sperm motility was suppressed is much lower than the pH of testicular fluid (Faure et al 1994, Demoy-Schneider et al 2012 and ii) 5-HT induced sperm motility in Manila clam and Pacific oyster under acidic conditions, which is consistent with stimulation of germinal vesicle breakdown (GVBD) in the oocytes by 5-HT at similar pH ( Osanai 1985). In 5-HT containing NH 3 , sperm motility was triggered immediately (Fig.…”

“…Until now, inhibitory factors for sperm motility have been identified in mammals, fish, and invertebrates including sea urchins, ascidians, and starfish (Tosti 1994, Verma 2001. Despite the inhibitory effects of acidic pH on sperm motility in marine bivalve mollusks (Faure et al 1994, Dong et al 2002, Ohta et al 2007, Demoy-Schneider et al 2012, there is a significant lack of information to clarify the contribution of different ions. Sperm signaling in the initiation of motility mediated by pH, certain ions, or osmolality has been extensively studied in invertebrates and mammals (Darszon et al 1999, Inaba 2003, Yoshida et al 2008 and in fish (Alavi & Cosson 2005, Morisawa 2008.…”