Inhibitory effect of osmotic concentration, potassium and pH on motility of the sperm of the North American burbot Lota lota maculosa

Abstract

Seminal plasma factors maintaining North American (NA) burbot Lota lota maculosa sperm quiescent were examined. Sperm were diluted into buffered saline solutions of various compositions and motility assessed. After 1 h in these solutions at 10°C, aliquots of the suspension were diluted with tap water and motility again assessed. Dilution of sperm in an incubation solution containing Ca 2þ in the absence of K þ initiated sperm motility resulting in low motility when sperm were subsequently diluted in tap water. Incubation solutions with osmolalities >200 mOsm kg ÿ1 and containing 12Á5 mM K þ prevented the onset of sperm motility and were associated with maximal sperm motility upon dilution in tap water. Sperm maintained at lower osmolalities exhibited limited motility upon dilution in tap water indicating interdependence between K þ and osmolality in maintaining sperm quiescent in the presence of Ca 2þ . Sperm kept in incubation solution at pH values < c. 7Á5 for 1 h demonstrated reduced motility when subsequently diluted in tap water. That motility of sperm was pH sensitive was further indicated by CO 2 inhibition of motility. Therefore, NA burbot sperm are probably maintained in an immotile state, yet with potential for motility, by combination of high K þ , osmolality and possibly pH. The results from this study differ from published information on sperm quiescence in the temporally and geographically distinct Eurasian burbot Lota lota lota.

Effects of temperature on sperm motility of burbot Lota lota: spontaneous activation and calcium dependency

“…In the present study, composition of L. lota seminal fluid was approximately similar to that reported in previous studies on L. lota (Lahnsteiner et al ., ; Dziewulska & Pilarska, ) and slightly differ from the composition of L. l. maculosa seminal fluid (Zuccarelli et al ., ). Based on our results, spontaneous activation of motility appeared at 20°C and maximum motility was recorded at 30°C (Table ), which was outside the temperature range (>5°C) reported by Lahnsteiner et al .…”

“…Zuccarelli et al . () demonstrated that a combination of high K + level, high osmolality and, probably, high pH is involved in keeping sperm in the quiescent state in seminal fluid in the L. l. maculosa . It has also been suggested that Ca 2+ plays a key role in the initiation of motility with a dose dependent response in L. l. maculosa sperm (Zuccarelli et al ., ).…”

“…Potassium (K + ) has been considered as the main inhibiting factor controlling spermatozoa activation of European L. lota and North American burbot Lota. L. maculosa LeSueur 1817 (Dziewulska & Pilarska, 2018;Zuccarelli et al, 2007). However, in L. lota the the inhibitory effect of K + on spermatozoa motility has not been proved by Lahnsteiner et al (1997).…”

Calcium‐induced quiescence of sperm motility in the bluegill (Lepomis macrochirus)

“…Motility of sperm was assessed within 5 sec of dilution of semen (41:1000; Woolsey et al, 2006) or following 60 min incubation (1:100) at 201C with subsequent dilution in tap water (1:10) following modified methods of Zuccarelli et al (2007). Fraction of total sperm demonstrating motility was assessed from sequential images captured 1 sec apart using the software Motic Images 2000 1.3 (Motic Incorporation Ltd., Hong Kong, China) in conjunction with a National DC3-163 microscope with digital camera (National Optical & Scientific Instruments Inc., San Antonio, TX).…”

“…tap water), the range of specific factors that maintain sperm quiescent in seminal plasma, before spawning, are not well established (Morisawa and Suzuki,'80;Morisawa et al,'83b,'91;Morisawa and Morisawa,'90;Lahnsteiner et al,'97). For example, in the Salmonidae, sperm are maintained immotile within seminal plasma by high K '91; Toth et al, '97;Alavi et al, 2004a,b;Lahnsteiner et al, 2004) as well as a freshwater gadid (Zuccarelli et al, 2007) are maintained immotile predominately by K 1 and osmolality and sperm of the Cyprinidae are maintained immotile solely by osmolality (Morisawa et al, '83c;Marian et al, '93;Krasznai et al, 2000Krasznai et al, , 2003aLinhart et al, 2003). Although carp and salmonid sperm are maintained in seminal plasma, cytoplasmic Ca 21 is maintained at low levels (Okuno and Morisawa, '89;Krasznai et al, 2000).…”