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Though bivalve mollusks are keystone species and major species groups in aquaculture production worldwide, gamete biology is still largely unknown. This review aims to provide a synthesis of current knowledge in the field of sperm biology, including spermatozoa motility, flagellar beating, and energy metabolism; and to illustrate cellular signaling controlling spermatozoa motility initiation in bivalves. Serotonin (5-HT) induces hyper-motility in spermatozoa via a 5-HT receptor, suggesting a serotoninergic system in the male reproductive tract that might regulate sperm physiology. Acidic pH and high concentration of K+ are inhibitory factors of spermatozoa motility in the testis. Motility is initiated at spawning by a Na+-dependent alkalization of intracellular pH mediated by a Na+/H+ exchanger. Increase of 5-HT in the testis and decrease of extracellular K+ when sperm is released in seawater induce hyperpolarization of spermatozoa membrane potential mediated by K+ efflux and associated with an increase in intracellular Ca2+ via opening of voltage-dependent Ca2+ channels under alkaline conditions. These events activate dynein ATPases and Ca2+/calmodulin-dependent proteins resulting in flagellar beating. It may be possible that 5-HT is also involved in intracellular cAMP rise controlling cAMP-dependent protein kinase phosphorylation in the flagellum. Once motility is triggered, flagellum beats in asymmetric wave pattern leading to circular trajectories of spermatozoa. Three different flagellar wave characteristics are reported, including “full”, “twitching”, and “declining” propagation of wave, which are described and illustrated in the present review. Mitochondrial respiration, ATP content, and metabolic pathways producing ATP in bivalve spermatozoa are discussed. Energy metabolism of Pacific oyster spermatozoa differs from previously studied marine species since oxidative phosphorylation synthetizes a stable level of ATP throughout 24-h motility period and the end

Though bivalve mollusks are keystone species and major species groups in aquaculture production worldwide, gamete biology is still largely unknown. This review aims to provide a synthesis of current knowledge in the field of sperm biology, including spermatozoa motility, flagellar beating, and energy metabolism; and to illustrate cellular signaling controlling spermatozoa motility initiation in bivalves. Serotonin (5-HT) induces hyper-motility in spermatozoa via a 5-HT receptor, suggesting a serotoninergic system in the male reproductive tract that might regulate sperm physiology. Acidic pH and high concentration of K+ are inhibitory factors of spermatozoa motility in the testis. Motility is initiated at spawning by a Na+-dependent alkalization of intracellular pH mediated by a Na+/H+ exchanger. Increase of 5-HT in the testis and decrease of extracellular K+ when sperm is released in seawater induce hyperpolarization of spermatozoa membrane potential mediated by K+ efflux and associated with an increase in intracellular Ca2+ via opening of voltage-dependent Ca2+ channels under alkaline conditions. These events activate dynein ATPases and Ca2+/calmodulin-dependent proteins resulting in flagellar beating. It may be possible that 5-HT is also involved in intracellular cAMP rise controlling cAMP-dependent protein kinase phosphorylation in the flagellum. Once motility is triggered, flagellum beats in asymmetric wave pattern leading to circular trajectories of spermatozoa. Three different flagellar wave characteristics are reported, including “full”, “twitching”, and “declining” propagation of wave, which are described and illustrated in the present review. Mitochondrial respiration, ATP content, and metabolic pathways producing ATP in bivalve spermatozoa are discussed. Energy metabolism of Pacific oyster spermatozoa differs from previously studied marine species since oxidative phosphorylation synthetizes a stable level of ATP throughout 24-h motility period and the end

Though bivalve mollusks are keystone species and major species groups in aquaculture production worldwide, gamete biology is still largely unknown. This review aims to provide a synthesis of current knowledge in the field of sperm biology, including spermatozoa motility, flagellar beating, and energy metabolism; and to illustrate cellular signaling controlling spermatozoa motility initiation in bivalves. Serotonin (5-HT) induces hyper-motility in spermatozoa via a 5-HT receptor, suggesting a serotoninergic system in the male reproductive tract that might regulate sperm physiology. Acidic pH and high concentration of K+ are inhibitory factors of spermatozoa motility in the testis. Motility is initiated at spawning by a Na+-dependent alkalization of intracellular pH mediated by a Na+/H+ exchanger. Increase of 5-HT in the testis and decrease of extracellular K+ when sperm is released in seawater induce hyperpolarization of spermatozoa membrane potential mediated by K+ efflux and associated with an increase in intracellular Ca2+ via opening of voltage-dependent Ca2+ channels under alkaline conditions. These events activate dynein ATPases and Ca2+/calmodulin-dependent proteins resulting in flagellar beating. It may be possible that 5-HT is also involved in intracellular cAMP rise controlling cAMP-dependent protein kinase phosphorylation in the flagellum. Once motility is triggered, flagellum beats in asymmetric wave pattern leading to circular trajectories of spermatozoa. Three different flagellar wave characteristics are reported, including “full”, “twitching”, and “declining” propagation of wave, which are described and illustrated in the present review. Mitochondrial respiration, ATP content, and metabolic pathways producing ATP in bivalve spermatozoa are discussed. Energy metabolism of Pacific oyster spermatozoa differs from previously studied marine species since oxidative phosphorylation synthetizes a stable level of ATP throughout 24-h motility period and the end

Current rates of biodiversity loss pose an unprecedented challenge to the conservation community, particularly with amphibians and freshwater fish as the most threatened vertebrates. An increasing number of environmental challenges, including habitat loss, pathogens, and global warming, demand a global response toward the sustainable management of ecosystems and their biodiversity. Conservation Breeding Programs (CBPs) are needed for the sustainable management of amphibian species threatened with extinction. CBPs support species survival while increasing public awareness and political influence. Current CBPs only cater for 10% of the almost 500 amphibian species in need. However, the use of sperm storage to increase efficiency and reliability, along with an increased number of CBPs, offer the potential to significantly reduce species loss. The establishment and refinement of techniques over the last two decades, for the collection and storage of amphibian spermatozoa, gives confidence for their use in CBPs and other biotechnical applications. Cryopreserved spermatozoa has produced breeding pairs of frogs and salamanders and the stage is set for Lifecycle Proof of Concept Programs that use cryopreserved sperm in CBPs along with repopulation, supplementation, and translocation programs. The application of cryopreserved sperm in CBPs, is complimentary to but separate from archival gene banking and general cell and tissue storage. However, where appropriate amphibian sperm banking should be integrated into other global biobanking projects, especially those for fish, and those that include the use of cryopreserved material for genomics and other research. Research over a broader range of amphibian species, and more uniformity in experimental methodology, is needed to inform both theory and application. Genomics is revolutionising our understanding of biological processes and increasingly guiding species conservation through the identification of evolutionary significant

High quality of sperm is essential to a high fertilization rate, especially post- cryopreservation. Assessment of sperm integrity, motility and energy reserves before cryopreservation is necessary for selection of milt with optimal fertilizing potential. We describe the effect of cryopreservation on the quality of black-lip pearl oyster, Pinctada margaritifera var. cumingii sperm. Evaluated quality indices of fresh and frozen/thawed P. margaritifera spermatozoa, included morphology, ultrastructure and motility characteristics relative to the energy content (ATP) and its capacity to be sustained by mitochondrial respiration. Morphology and ultrastructure were quantitatively evaluated using images obtained by optical microscopy assisted by the Image J software and TEM, respectively. Sperm motility was assessed using Image J software combined with a computer assisted sperm analysis plugin adapted for assessing P. margaritifera spermatozoa. Other sperm quality parameters evaluated included O2 consumption, ATP content, and creatine kinase activity. Frozen/thawed spermatozoa exhibited damage to the head but retained a compact spherical shape. Sperm motility indicators showed a significant decrease in quality resulting from the freeze/thaw process. The percent of motile cells was 54% compared to 84% in fresh sperm, O2 consumption was 4.8 compared to 44 nanomol min−1, ATP content was 0.72 nmol/109 spermatozoa in the activating medium compared to 4.54 nmol/109 spermatozoa, and creatine kinase activity was 9.06 × 10−5 IU mg−1 protein compared to 12.5 × 10−5 IU mg−1 protein. The cryopreservation protocol allowed obtaining an acceptable motility rate after thawing, confirming the predictive value of sperm motility measurements before cryopreservation in terms of their ability to withstand freezing process.

Investigating the roles of chemical factors stimulating and inhibiting sperm motility is required to understand the mechanisms of spermatozoa movement. In this study, we described the composition of the seminal fluid (osmotic pressure, pH, and ions) and investigated the roles of these factors and salinity in initiating spermatozoa movement in the Pacific oyster. The acidic pH of the gonad (5.82 ± 0.22) maintained sperm in the quiescent stage and initiation of flagellar movement was triggered by a sudden increase of spermatozoa external pH (pHe) when released in seawater (SW). At pH 6.4, percentage of motile spermatozoa was three times higher when they were activated in SW containing 30 mM NH4Cl, which alkalinizes internal pH (pHi) of spermatozoa, compared to NH4Cl-free SW, revealing the role of pHi in triggering sperm movement. Percentage of motile spermatozoa activated in Na+-free artificial seawater (ASW) was highly reduced compared to ASW, suggesting that change of pHi triggering sperm motility was mediated by a Na+/H+ exchanger. Motility and swimming speed were highest in salinities between 33.8 and 42.7‰ (within a range of 0 to 50 ‰), and pH values above 7.5 (within a range of 4.5 to 9.5).

High quality of sperm is essential to a high fertilization rate, especially post- cryopreservation. Assessment of sperm integrity, motility and energy reserves before cryopreservation is necessary for selection of milt with optimal fertilizing potential. We describe the effect of cryopreservation on the quality of black-lip pearl oyster, Pinctada margaritifera var. cumingii sperm. Evaluated quality indices of fresh and frozen/thawed P. margaritifera spermatozoa, included morphology, ultrastructure and motility characteristics relative to the energy content (ATP) and its capacity to be sustained by mitochondrial respiration. Morphology and ultrastructure were quantitatively evaluated using images obtained by optical microscopy assisted by the Image J software and TEM, respectively. Sperm motility was assessed using Image J software combined with a computer assisted sperm analysis plugin adapted for assessing P. margaritifera spermatozoa. Other sperm quality parameters evaluated included O2 consumption, ATP content, and creatine kinase activity. Frozen/thawed spermatozoa exhibited damage to the head but retained a compact spherical shape. Sperm motility indicators showed a significant decrease in quality resulting from the freeze/thaw process. The percent of motile cells was 54% compared to 84% in fresh sperm, O2 consumption was 4.8 compared to 44 nanomol min−1, ATP content was 0.72 nmol/109 spermatozoa in the activating medium compared to 4.54 nmol/109 spermatozoa, and creatine kinase activity was 9.06 × 10−5 IU mg−1 protein compared to 12.5 × 10−5 IU mg−1 protein. The cryopreservation protocol allowed obtaining an acceptable motility rate after thawing, confirming the predictive value of sperm motility measurements before cryopreservation in terms of their ability to withstand freezing process.

Investigating the roles of chemical factors stimulating and inhibiting sperm motility is required to understand the mechanisms of spermatozoa movement. In this study, we described the composition of the seminal fluid (osmotic pressure, pH, and ions) and investigated the roles of these factors and salinity in initiating spermatozoa movement in the Pacific oyster. The acidic pH of the gonad (5.82 ± 0.22) maintained sperm in the quiescent stage and initiation of flagellar movement was triggered by a sudden increase of spermatozoa external pH (pHe) when released in seawater (SW). At pH 6.4, percentage of motile spermatozoa was three times higher when they were activated in SW containing 30 mM NH4Cl, which alkalinizes internal pH (pHi) of spermatozoa, compared to NH4Cl-free SW, revealing the role of pHi in triggering sperm movement. Percentage of motile spermatozoa activated in Na+-free artificial seawater (ASW) was highly reduced compared to ASW, suggesting that change of pHi triggering sperm motility was mediated by a Na+/H+ exchanger. Motility and swimming speed were highest in salinities between 33.8 and 42.7‰ (within a range of 0 to 50 ‰), and pH values above 7.5 (within a range of 4.5 to 9.5).

High quality of sperm is essential to a high fertilization rate, especially post- cryopreservation. Assessment of sperm integrity, motility and energy reserves before cryopreservation is necessary for selection of milt with optimal fertilizing potential. We describe the effect of cryopreservation on the quality of black-lip pearl oyster, Pinctada margaritifera var. cumingii sperm. Evaluated quality indices of fresh and frozen/thawed P. margaritifera spermatozoa, included morphology, ultrastructure and motility characteristics relative to the energy content (ATP) and its capacity to be sustained by mitochondrial respiration. Morphology and ultrastructure were quantitatively evaluated using images obtained by optical microscopy assisted by the Image J software and TEM, respectively. Sperm motility was assessed using Image J software combined with a computer assisted sperm analysis plugin adapted for assessing P. margaritifera spermatozoa. Other sperm quality parameters evaluated included O2 consumption, ATP content, and creatine kinase activity. Frozen/thawed spermatozoa exhibited damage to the head but retained a compact spherical shape. Sperm motility indicators showed a significant decrease in quality resulting from the freeze/thaw process. The percent of motile cells was 54% compared to 84% in fresh sperm, O2 consumption was 4.8 compared to 44 nanomol min−1, ATP content was 0.72 nmol/109 spermatozoa in the activating medium compared to 4.54 nmol/109 spermatozoa, and creatine kinase activity was 9.06 × 10−5 IU mg−1 protein compared to 12.5 × 10−5 IU mg−1 protein. The cryopreservation protocol allowed obtaining an acceptable motility rate after thawing, confirming the predictive value of sperm motility measurements before cryopreservation in terms of their ability to withstand freezing process.

Investigating the roles of chemical factors stimulating and inhibiting sperm motility is required to understand the mechanisms of spermatozoa movement. In this study, we described the composition of the seminal fluid (osmotic pressure, pH, and ions) and investigated the roles of these factors and salinity in initiating spermatozoa movement in the Pacific oyster. The acidic pH of the gonad (5.82 ± 0.22) maintained sperm in the quiescent stage and initiation of flagellar movement was triggered by a sudden increase of spermatozoa external pH (pHe) when released in seawater (SW). At pH 6.4, percentage of motile spermatozoa was three times higher when they were activated in SW containing 30 mM NH4Cl, which alkalinizes internal pH (pHi) of spermatozoa, compared to NH4Cl-free SW, revealing the role of pHi in triggering sperm movement. Percentage of motile spermatozoa activated in Na+-free artificial seawater (ASW) was highly reduced compared to ASW, suggesting that change of pHi triggering sperm motility was mediated by a Na+/H+ exchanger. Motility and swimming speed were highest in salinities between 33.8 and 42.7‰ (within a range of 0 to 50 ‰), and pH values above 7.5 (within a range of 4.5 to 9.5).

Sperm characteristics of scallops have not been well described in the scientific literature. The effects of sperm release technique (thermal shock versus serotonin injection), of sperm collection technique (testis sampling versus serotonin injection), of sperm sampling location along the genital tract, of in vitro sperm maturation, and of time post activation on scallop sperm characteristics were assessed in the present work. Whatever sperm release technique used, no significant differences were observed regarding the percentage of motile spermatozoa and the velocity of the average path (YAP). Compared to testicular sperm, a higher percentage of motile spermatozoa, YAP and intracellular adenosine triphosphate (ATP) content were observed for sperm shed after serotonin injection. From the distal part of testes up to the gonopore, an increase of the percentage of motile spermatozoa and YAP was assessed, suggesting a sperm 'maturation process' along the genital ducts. A higher increase in the percentage of motile sperm was recorded during a 5 mm incubation of testicular sperm in seawater containing 2 mM serotonin and seawater containing 10 mM caffein compared to seawater (control). In addition, a higher YAP was assessed, incubating testicular sperm in caffein, compared to control or serotonin. Then, the percentage of motile spermatozoa, YAP and intracellular ATP content exhibited a progressive reduction during the 10 h swimming period. Mean values of the percentage of motile spermatozoa, YAP, sperm track linearity (LIN) and intracellular ATP content recorded at the beginning of the movement period for sperm samples collected after intragonadal serotonin injection, were 82 +/- 7%, 162 +/- 15 mu m s(-1), 0.33 +/- 0.12 and 212 +/- 133 nmol x 10(-9) spermatozoa (n = 9 males), respectively. The present study confirms the existence of a sperm "maturation process" along scallop genital ducts. In addition, the cessation of scallop sperm movement can be explained by the exhausti

Sperm characteristics of scallops have not been well described in the scientific literature. The effects of sperm release technique (thermal shock versus serotonin injection), of sperm collection technique (testis sampling versus serotonin injection), of sperm sampling location along the genital tract, of in vitro sperm maturation, and of time post activation on scallop sperm characteristics were assessed in the present work. Whatever sperm release technique used, no significant differences were observed regarding the percentage of motile spermatozoa and the velocity of the average path (YAP). Compared to testicular sperm, a higher percentage of motile spermatozoa, YAP and intracellular adenosine triphosphate (ATP) content were observed for sperm shed after serotonin injection. From the distal part of testes up to the gonopore, an increase of the percentage of motile spermatozoa and YAP was assessed, suggesting a sperm 'maturation process' along the genital ducts. A higher increase in the percentage of motile sperm was recorded during a 5 mm incubation of testicular sperm in seawater containing 2 mM serotonin and seawater containing 10 mM caffein compared to seawater (control). In addition, a higher YAP was assessed, incubating testicular sperm in caffein, compared to control or serotonin. Then, the percentage of motile spermatozoa, YAP and intracellular ATP content exhibited a progressive reduction during the 10 h swimming period. Mean values of the percentage of motile spermatozoa, YAP, sperm track linearity (LIN) and intracellular ATP content recorded at the beginning of the movement period for sperm samples collected after intragonadal serotonin injection, were 82 +/- 7%, 162 +/- 15 mu m s(-1), 0.33 +/- 0.12 and 212 +/- 133 nmol x 10(-9) spermatozoa (n = 9 males), respectively. The present study confirms the existence of a sperm "maturation process" along scallop genital ducts. In addition, the cessation of scallop sperm movement can be explained by the exhausti

Sperm characteristics of scallops have not been well described in the scientific literature. The effects of sperm release technique (thermal shock versus serotonin injection), of sperm collection technique (testis sampling versus serotonin injection), of sperm sampling location along the genital tract, of in vitro sperm maturation, and of time post activation on scallop sperm characteristics were assessed in the present work. Whatever sperm release technique used, no significant differences were observed regarding the percentage of motile spermatozoa and the velocity of the average path (YAP). Compared to testicular sperm, a higher percentage of motile spermatozoa, YAP and intracellular adenosine triphosphate (ATP) content were observed for sperm shed after serotonin injection. From the distal part of testes up to the gonopore, an increase of the percentage of motile spermatozoa and YAP was assessed, suggesting a sperm 'maturation process' along the genital ducts. A higher increase in the percentage of motile sperm was recorded during a 5 mm incubation of testicular sperm in seawater containing 2 mM serotonin and seawater containing 10 mM caffein compared to seawater (control). In addition, a higher YAP was assessed, incubating testicular sperm in caffein, compared to control or serotonin. Then, the percentage of motile spermatozoa, YAP and intracellular ATP content exhibited a progressive reduction during the 10 h swimming period. Mean values of the percentage of motile spermatozoa, YAP, sperm track linearity (LIN) and intracellular ATP content recorded at the beginning of the movement period for sperm samples collected after intragonadal serotonin injection, were 82 +/- 7%, 162 +/- 15 mu m s(-1), 0.33 +/- 0.12 and 212 +/- 133 nmol x 10(-9) spermatozoa (n = 9 males), respectively. The present study confirms the existence of a sperm "maturation process" along scallop genital ducts. In addition, the cessation of scallop sperm movement can be explained by the exhausti

Due to stock declines there is a growing interest in farming of European hake Merluccius merluccius. Thus, knowledge of its sperm biology is of importance not only for purposes of broodstock management, but also for the development of sperm preservation techniques. Hake sperm were collected from mature males caught during the summer-early autumn waters off western Norway and during the winter-early spring in the Bay of Biscay (France). Sperm quality characteristics were assessed after storage at 4 degrees C for 25 +/- 14 h. Average (+/- SD) values for Norwegian and French samples respectively were (i) sperm volume: 3.9 +/- 4.0 and 2.6 +/- 4.0 ml; (ii) spermatozoa concentration: 6.6 +/- 3.2 and 13.9 +/- 5.1 x 10(9) spermatozoa/ml; (iii) spermatocrit: 80.2 +/- 3.3 and 81.8 +/- 10.7%; and (iv) total number of spermatozoa: 23.5 +/- 30.0 and 35.1 +/- 36.2 x 10(9). Average osmolality and pH (+/- SD) of French samples were 349 +/- 28 mOsmol/kg and 7.6 +/- 0.1, respectively. Activation by transfer into full sea water (100 SW) or 10% ovarian fluid in sea water (10 OF) occurred synchronously for virtually all spermatozoa and the percent sperm motile decreased with post activation time. When transferred into 50% sea water diluted with distilled water (50 SW) only a few spermatozoa were activated initially but subsequently reached a maximum percentage of motility followed by a decline. Hake sperm motility declined rapidly to 50% of motility 70 s after activation with 100 SW. Sperm were motile for longer when activated with 50 SW (1570 +/- 295 s) or 10 OF (718 +/- 71 s) compared to 100 SW (317 +/- 121 s). Undiluted hake sperm stored at 4 degrees C up to 10 days retained 10% motility when activated with 100 SW. When cryopreserved, the motility recovery index of the cells at thawing ranged from 0 to 76.4%. These results describe for the first time the sperm traits of European hake following successful cryopreservation, and also show the importance of activation medium on sperm mot

Due to stock declines there is a growing interest in farming of European hake Merluccius merluccius. Thus, knowledge of its sperm biology is of importance not only for purposes of broodstock management, but also for the development of sperm preservation techniques. Hake sperm were collected from mature males caught during the summer-early autumn waters off western Norway and during the winter-early spring in the Bay of Biscay (France). Sperm quality characteristics were assessed after storage at 4 degrees C for 25 +/- 14 h. Average (+/- SD) values for Norwegian and French samples respectively were (i) sperm volume: 3.9 +/- 4.0 and 2.6 +/- 4.0 ml; (ii) spermatozoa concentration: 6.6 +/- 3.2 and 13.9 +/- 5.1 x 10(9) spermatozoa/ml; (iii) spermatocrit: 80.2 +/- 3.3 and 81.8 +/- 10.7%; and (iv) total number of spermatozoa: 23.5 +/- 30.0 and 35.1 +/- 36.2 x 10(9). Average osmolality and pH (+/- SD) of French samples were 349 +/- 28 mOsmol/kg and 7.6 +/- 0.1, respectively. Activation by transfer into full sea water (100 SW) or 10% ovarian fluid in sea water (10 OF) occurred synchronously for virtually all spermatozoa and the percent sperm motile decreased with post activation time. When transferred into 50% sea water diluted with distilled water (50 SW) only a few spermatozoa were activated initially but subsequently reached a maximum percentage of motility followed by a decline. Hake sperm motility declined rapidly to 50% of motility 70 s after activation with 100 SW. Sperm were motile for longer when activated with 50 SW (1570 +/- 295 s) or 10 OF (718 +/- 71 s) compared to 100 SW (317 +/- 121 s). Undiluted hake sperm stored at 4 degrees C up to 10 days retained 10% motility when activated with 100 SW. When cryopreserved, the motility recovery index of the cells at thawing ranged from 0 to 76.4%. These results describe for the first time the sperm traits of European hake following successful cryopreservation, and also show the importance of activation medium on sperm mot

Due to stock declines there is a growing interest in farming of European hake Merluccius merluccius. Thus, knowledge of its sperm biology is of importance not only for purposes of broodstock management, but also for the development of sperm preservation techniques. Hake sperm were collected from mature males caught during the summer-early autumn waters off western Norway and during the winter-early spring in the Bay of Biscay (France). Sperm quality characteristics were assessed after storage at 4 degrees C for 25 +/- 14 h. Average (+/- SD) values for Norwegian and French samples respectively were (i) sperm volume: 3.9 +/- 4.0 and 2.6 +/- 4.0 ml; (ii) spermatozoa concentration: 6.6 +/- 3.2 and 13.9 +/- 5.1 x 10(9) spermatozoa/ml; (iii) spermatocrit: 80.2 +/- 3.3 and 81.8 +/- 10.7%; and (iv) total number of spermatozoa: 23.5 +/- 30.0 and 35.1 +/- 36.2 x 10(9). Average osmolality and pH (+/- SD) of French samples were 349 +/- 28 mOsmol/kg and 7.6 +/- 0.1, respectively. Activation by transfer into full sea water (100 SW) or 10% ovarian fluid in sea water (10 OF) occurred synchronously for virtually all spermatozoa and the percent sperm motile decreased with post activation time. When transferred into 50% sea water diluted with distilled water (50 SW) only a few spermatozoa were activated initially but subsequently reached a maximum percentage of motility followed by a decline. Hake sperm motility declined rapidly to 50% of motility 70 s after activation with 100 SW. Sperm were motile for longer when activated with 50 SW (1570 +/- 295 s) or 10 OF (718 +/- 71 s) compared to 100 SW (317 +/- 121 s). Undiluted hake sperm stored at 4 degrees C up to 10 days retained 10% motility when activated with 100 SW. When cryopreserved, the motility recovery index of the cells at thawing ranged from 0 to 76.4%. These results describe for the first time the sperm traits of European hake following successful cryopreservation, and also show the importance of activation medium on sperm mot

As in many marine fish, motility is triggered by osmotic pressure (OP) in cod and hake spermatozoa and motility ranges several minutes with a high velocity (above 50 mu m/s) period restricted to 100 s. A decrease in the flagellar beat frequency (BF) is partly responsible of this briefness. Detailed observations of the flagella during the motility period showed: 1) sea water provokes OP damages (blebs) which impair the correct wave propagation 2) waves become restricted to the proximal flagellum and tip becomes devoid of wave 3) the wave amplitude decreases. The combination of these factors drastically limits to the earliest period of motility the ability for spermatozoa to efficiently progress towards egg for fertilization.

Very little is known on European hake's reproductive biology and especially on biological characteristics of its sperm despite a growing interest in its aquaculture potential. This study reports, for the first time some hake sperm characteristics. After activation, the swimming phase lasts 3 min (8 min when activated with 50% sea water (SW) but lower initial velocity). The initial flagellar beat frequency (BF), velocity and percentage of motile cells decreased after 100 s. After 2 days at 4 degrees C, the mean Adenylate Energy Charge (AEC) level was 0.71. Sperm stored at 4 degrees C still showed motility after 9 days for 2 individuals. When cryopreserved, the motility recovery index of thawed spermatozoa ranged from 11.8% to 29.6%.

Very little is known on European hake's reproductive biology and especially on biological characteristics of its sperm despite a growing interest in its aquaculture potential. This study reports, for the first time some hake sperm characteristics. After activation, the swimming phase lasts 3 min (8 min when activated with 50% sea water (SW) but lower initial velocity). The initial flagellar beat frequency (BF), velocity and percentage of motile cells decreased after 100 s. After 2 days at 4 degrees C, the mean Adenylate Energy Charge (AEC) level was 0.71. Sperm stored at 4 degrees C still showed motility after 9 days for 2 individuals. When cryopreserved, the motility recovery index of thawed spermatozoa ranged from 11.8% to 29.6%.

As in many marine fish, motility is triggered by osmotic pressure (OP) in cod and hake spermatozoa and motility ranges several minutes with a high velocity (above 50 mu m/s) period restricted to 100 s. A decrease in the flagellar beat frequency (BF) is partly responsible of this briefness. Detailed observations of the flagella during the motility period showed: 1) sea water provokes OP damages (blebs) which impair the correct wave propagation 2) waves become restricted to the proximal flagellum and tip becomes devoid of wave 3) the wave amplitude decreases. The combination of these factors drastically limits to the earliest period of motility the ability for spermatozoa to efficiently progress towards egg for fertilization.

Very little is known on European hake's reproductive biology and especially on biological characteristics of its sperm despite a growing interest in its aquaculture potential. This study reports, for the first time some hake sperm characteristics. After activation, the swimming phase lasts 3 min (8 min when activated with 50% sea water (SW) but lower initial velocity). The initial flagellar beat frequency (BF), velocity and percentage of motile cells decreased after 100 s. After 2 days at 4 degrees C, the mean Adenylate Energy Charge (AEC) level was 0.71. Sperm stored at 4 degrees C still showed motility after 9 days for 2 individuals. When cryopreserved, the motility recovery index of thawed spermatozoa ranged from 11.8% to 29.6%.

As in many marine fish, motility is triggered by osmotic pressure (OP) in cod and hake spermatozoa and motility ranges several minutes with a high velocity (above 50 mu m/s) period restricted to 100 s. A decrease in the flagellar beat frequency (BF) is partly responsible of this briefness. Detailed observations of the flagella during the motility period showed: 1) sea water provokes OP damages (blebs) which impair the correct wave propagation 2) waves become restricted to the proximal flagellum and tip becomes devoid of wave 3) the wave amplitude decreases. The combination of these factors drastically limits to the earliest period of motility the ability for spermatozoa to efficiently progress towards egg for fertilization.

Very little is known on European hake's reproductive biology and especially on biological characteristics of its sperm despite a growing interest in its aquaculture potential. This study reports, for the first time some hake sperm characteristics. After activation, the swimming phase lasts 3 min (8 min when activated with 50% sea water (SW) but lower initial velocity). The initial flagellar beat frequency (BF), velocity and percentage of motile cells decreased after 100 s. After 2 days at 4 degrees C, the mean Adenylate Energy Charge (AEC) level was 0.71. Sperm stored at 4 degrees C still showed motility after 9 days for 2 individuals. When cryopreserved, the motility recovery index of thawed spermatozoa ranged from 11.8% to 29.6%.

As in many marine fish, motility is triggered by osmotic pressure (OP) in cod and hake spermatozoa and motility ranges several minutes with a high velocity (above 50 mu m/s) period restricted to 100 s. A decrease in the flagellar beat frequency (BF) is partly responsible of this briefness. Detailed observations of the flagella during the motility period showed: 1) sea water provokes OP damages (blebs) which impair the correct wave propagation 2) waves become restricted to the proximal flagellum and tip becomes devoid of wave 3) the wave amplitude decreases. The combination of these factors drastically limits to the earliest period of motility the ability for spermatozoa to efficiently progress towards egg for fertilization.

This paper presents some features of turbot sperm and compares them with data reported in the literature on other freshwater and marine fish. In captivity, turbot spermiation period lasts 6 months. When compared to other fish species, turbot males are characterized by low values of maximum gonadosomatic index (0.6-0.8%) and are poor sperm producers in terms of volume (0.2-2.2 ml), concentration (0.7-11.0 x 10(9) spermatozoa/ml) and total sperm number released per stripping (0.2-12.0 x 10(9) spermatozoa). Compared to most freshwater species, the duration of cell movement is long (1-17 min). The spermatozoon of turbot can be considered to be of a primitive type. A very high protein content (8.8 mg/ml) is found in the seminal fluid of turbot. Increasing collection frequency of turbot males, from monthly to fortnightly and weekly stripping, results in the release of successive samples presenting decreasing semen volume and spermatozoa concentration. Similar spermatozoa concentration and total volume of semen produced per turbot, during a 2-month experimental period, are released from males submitted to an annual light and temperature cycle, compared to those receiving a 6 month contracted light and temperature schedule., Les caractéristiques du sperme de turbot sont comparées aux données existantes de la littérature chez quelques poissons marins ou d'eau douce. En captivité, la période de spermiation dure 6 mois. Comparé à d'autres espèces de poisson, le turbot mâle présente des valeurs maximales peu élevées du rapport gonado-somatique (0,6-0,8%) et produit de faibles volumes de sperme (0,2-2,2 ml), concentration (0,7-11,0 x IO9 spermatozoïdes/ml) et nombre total de spermatozoïdes récoltés par prélèvement (0,2- 12.0 x I09 spermatozoïdes). Comparé à la plupart des poissons d'eau douce, la durée du mouvement des spermatozoïdes est élevée (1-17 min). Le spermatozoïde de turbot peut être considéré comme appartenant au type primitif. Une concentration élevée en protéines (8,8 mg/ml) est mesurée dans le liquide séminal de turbot. L'augmentation de la fréquence de prélèvement du sperme, d'une fois par mois à une fois tous les 15 jours ou une fois par semaine, affecte la concentration en spermatozoïdes et le volume de sperme récolté par prélbvement. La concentration en spermatozoïdes et le volume total de sperme récolté par turbot, durant une période expérimentale de 2 mois, ne sont pas modifiés, lorsque le cycle annuel de photopériode et température est contracté sur une période de 6 mois.

This paper presents some features of turbot sperm and compares them with data reported in the literature on other freshwater and marine fish. In captivity, turbot spermiation period lasts 6 months. When compared to other fish species, turbot males are characterized by low values of maximum gonadosomatic index (0.6-0.8%) and are poor sperm producers in terms of volume (0.2-2.2 ml), concentration (0.7-11.0 x 10(9) spermatozoa/ml) and total sperm number released per stripping (0.2-12.0 x 10(9) spermatozoa). Compared to most freshwater species, the duration of cell movement is long (1-17 min). The spermatozoon of turbot can be considered to be of a primitive type. A very high protein content (8.8 mg/ml) is found in the seminal fluid of turbot. Increasing collection frequency of turbot males, from monthly to fortnightly and weekly stripping, results in the release of successive samples presenting decreasing semen volume and spermatozoa concentration. Similar spermatozoa concentration and total volume of semen produced per turbot, during a 2-month experimental period, are released from males submitted to an annual light and temperature cycle, compared to those receiving a 6 month contracted light and temperature schedule., Les caractéristiques du sperme de turbot sont comparées aux données existantes de la littérature chez quelques poissons marins ou d'eau douce. En captivité, la période de spermiation dure 6 mois. Comparé à d'autres espèces de poisson, le turbot mâle présente des valeurs maximales peu élevées du rapport gonado-somatique (0,6-0,8%) et produit de faibles volumes de sperme (0,2-2,2 ml), concentration (0,7-11,0 x IO9 spermatozoïdes/ml) et nombre total de spermatozoïdes récoltés par prélèvement (0,2- 12.0 x I09 spermatozoïdes). Comparé à la plupart des poissons d'eau douce, la durée du mouvement des spermatozoïdes est élevée (1-17 min). Le spermatozoïde de turbot peut être considéré comme appartenant au type primitif. Une concentration élevée en protéines (8,8 mg/ml) est mesurée dans le liquide séminal de turbot. L'augmentation de la fréquence de prélèvement du sperme, d'une fois par mois à une fois tous les 15 jours ou une fois par semaine, affecte la concentration en spermatozoïdes et le volume de sperme récolté par prélbvement. La concentration en spermatozoïdes et le volume total de sperme récolté par turbot, durant une période expérimentale de 2 mois, ne sont pas modifiés, lorsque le cycle annuel de photopériode et température est contracté sur une période de 6 mois.

This paper presents some features of turbot sperm and compares them with data reported in the literature on other freshwater and marine fish. In captivity, turbot spermiation period lasts 6 months. When compared to other fish species, turbot males are characterized by low values of maximum gonadosomatic index (0.6-0.8%) and are poor sperm producers in terms of volume (0.2-2.2 ml), concentration (0.7-11.0 x 10(9) spermatozoa/ml) and total sperm number released per stripping (0.2-12.0 x 10(9) spermatozoa). Compared to most freshwater species, the duration of cell movement is long (1-17 min). The spermatozoon of turbot can be considered to be of a primitive type. A very high protein content (8.8 mg/ml) is found in the seminal fluid of turbot. Increasing collection frequency of turbot males, from monthly to fortnightly and weekly stripping, results in the release of successive samples presenting decreasing semen volume and spermatozoa concentration. Similar spermatozoa concentration and total volume of semen produced per turbot, during a 2-month experimental period, are released from males submitted to an annual light and temperature cycle, compared to those receiving a 6 month contracted light and temperature schedule., Les caractéristiques du sperme de turbot sont comparées aux données existantes de la littérature chez quelques poissons marins ou d'eau douce. En captivité, la période de spermiation dure 6 mois. Comparé à d'autres espèces de poisson, le turbot mâle présente des valeurs maximales peu élevées du rapport gonado-somatique (0,6-0,8%) et produit de faibles volumes de sperme (0,2-2,2 ml), concentration (0,7-11,0 x IO9 spermatozoïdes/ml) et nombre total de spermatozoïdes récoltés par prélèvement (0,2- 12.0 x I09 spermatozoïdes). Comparé à la plupart des poissons d'eau douce, la durée du mouvement des spermatozoïdes est élevée (1-17 min). Le spermatozoïde de turbot peut être considéré comme appartenant au type primitif. Une concentration élevée en protéines (8,8 mg/ml) est mesurée dans le liquide séminal de turbot. L'augmentation de la fréquence de prélèvement du sperme, d'une fois par mois à une fois tous les 15 jours ou une fois par semaine, affecte la concentration en spermatozoïdes et le volume de sperme récolté par prélbvement. La concentration en spermatozoïdes et le volume total de sperme récolté par turbot, durant une période expérimentale de 2 mois, ne sont pas modifiés, lorsque le cycle annuel de photopériode et température est contracté sur une période de 6 mois.