P. Zhuang

Isosmotic points and their ecological significance for juvenile Chinese sturgeon Acipenser sinensis.

Serum osmolality and ion concentrations were measured in juvenile Chinese sturgeon Acipenser sinensis at different salinities to determine the isosmotic point. Isosmotic and isoionic concentrations were calculated from the regressions for serum and ambient osmolality, with Na(+) , Cl(-) and K(+) as salinities 9·19, 8·17, 7·89 and 9·70, respectively. These values were consistent with the salinity of the habitat where juvenile A. sinensis occur in the Yangtze Estuary, suggesting that an isosmotic salinity is an important factor driving their habitat choice.

Effects of Cryoprotectant Toxicity on Embryos of the Chinese Mitten Crab, Eriocheir Sinensis (Decapoda, Brachyura)

[The response of embryos of the Chinese mitten crab ( Eriocheir sinensis ) in terms of survival to cryoprotectants was investigated for basic knowledge to enhance cryopreservation success of E. sinensis embryos. Five stages of embryonic development (cleavage, blastula, gastrula, eyed stage, and heart-beating stage embryos corresponding to 7, 14, 20, 26, and 31 days post-spawning) were chosen and exposed to various cryoprotectants, namely methanol (MeOH), propylene glycol (PG), dimethyl sulfoxide (DMSO), and dimethylformamide (DMF), at three concentrations (10, 15, 20%) for an experimental period of 30 min. at culture temperature (16°C). The toxicity tolerance of E. sinensis embryos varied with developmental stage and cryoprotectant concentration. Cleavage and blastula embryos were very sensitive to cryoprotectant concentrations above 10%. Gastrula, eyed stage, and heart-beating stage embryos tolerated cryoprotectants to 20%, although a higher survival percentage was observed in heart beating stage embryos than in gastrula and eyed stage embryos. The survival percentage declined with an increase in cryoprotectant concentration. PG and DMF were relatively less toxic as compared to DMSO and MeOH. Based on the sensitivity to cryoprotectant exposure, heart beating stage embryos of E. sinensis are an appropriate stage for further cryopreservation. La reponse des embryons du crabe chinois ( Eriocheir sinensis ) en terme de survie aux cryoprotecteurs a ete etudiee de facon a acquerir les connaissances de base afin daugmenter le succes de la cryopreservation des embryons de E. sinensis. Cinq stades du developpement embryonnaire (segmentation, blastula, gastrula, apparition de lœil et debut des battements cardiaques correspondant a 7, 14, 20, 26 et 31 jours apres la ponte) ont ete selectionnes et exposes a differents cryoprotecteurs, dont le methanol (MeOH), propylene glycol (PG), dimethyl sulfoxide (DMSO), et dimethylformamide (DMF), a trois concentrations (10, 15, 20%) pour une periode experimentale de 30 min a la temperature de culture (16°C). La tolerance des embryons de E. sinensis a varie avec le stade de developpement et la concentration du cryoprotecteur. Les embryons en segmentation et blastula ont ete tres sensibles aux concentrations de cryoprotecteur au dessus de 10%. Les stades gastrula, apparition de lœil et debut des battements cardiaques ont tolere des cryoprotecteurs jusqua 20%, bien quun pourcentage de survie plus eleve ait ete observe chez le stade debut des battements cardiaques par rapport aux embryons en gastrula ou apparition de lœil. Le pourcentage de survie diminue lors dune augmentation de la concentration de cryoprotecteur. PG et DMF ont ete relativement moins toxiques par rapport au DMSO et MeOH. Sur la base de leur sensibilite a lexposition de cryoprotecteurs les embryons au stade debut des battements cardiaques sont un stade approprie pour une aller plus loin dans la cryopreservation. , The response of embryos of the Chinese mitten crab ( Eriocheir sinensis ) in terms of survival to cryoprotectants was investigated for basic knowledge to enhance cryopreservation success of E. sinensis embryos. Five stages of embryonic development (cleavage, blastula, gastrula, eyed stage, and heart-beating stage embryos corresponding to 7, 14, 20, 26, and 31 days post-spawning) were chosen and exposed to various cryoprotectants, namely methanol (MeOH), propylene glycol (PG), dimethyl sulfoxide (DMSO), and dimethylformamide (DMF), at three concentrations (10, 15, 20%) for an experimental period of 30 min. at culture temperature (16°C). The toxicity tolerance of E. sinensis embryos varied with developmental stage and cryoprotectant concentration. Cleavage and blastula embryos were very sensitive to cryoprotectant concentrations above 10%. Gastrula, eyed stage, and heart-beating stage embryos tolerated cryoprotectants to 20%, although a higher survival percentage was observed in heart beating stage embryos than in gastrula and eyed stage embryos. The survival percentage declined with an increase in cryoprotectant concentration. PG and DMF were relatively less toxic as compared to DMSO and MeOH. Based on the sensitivity to cryoprotectant exposure, heart beating stage embryos of E. sinensis are an appropriate stage for further cryopreservation. La reponse des embryons du crabe chinois ( Eriocheir sinensis ) en terme de survie aux cryoprotecteurs a ete etudiee de facon a acquerir les connaissances de base afin daugmenter le succes de la cryopreservation des embryons de E. sinensis. Cinq stades du developpement embryonnaire (segmentation, blastula, gastrula, apparition de lœil et debut des battements cardiaques correspondant a 7, 14, 20, 26 et 31 jours apres la ponte) ont ete selectionnes et exposes a differents cryoprotecteurs, dont le methanol (MeOH), propylene glycol (PG), dimethyl sulfoxide (DMSO), et dimethylformamide (DMF), a trois concentrations (10, 15, 20%) pour une periode experimentale de 30 min a la temperature de culture (16°C). La tolerance des embryons de E. sinensis a varie avec le stade de developpement et la concentration du cryoprotecteur. Les embryons en segmentation et blastula ont ete tres sensibles aux concentrations de cryoprotecteur au dessus de 10%. Les stades gastrula, apparition de lœil et debut des battements cardiaques ont tolere des cryoprotecteurs jusqua 20%, bien quun pourcentage de survie plus eleve ait ete observe chez le stade debut des battements cardiaques par rapport aux embryons en gastrula ou apparition de lœil. Le pourcentage de survie diminue lors dune augmentation de la concentration de cryoprotecteur. PG et DMF ont ete relativement moins toxiques par rapport au DMSO et MeOH. Sur la base de leur sensibilite a lexposition de cryoprotecteurs les embryons au stade debut des battements cardiaques sont un stade approprie pour une aller plus loin dans la cryopreservation. ]

Effects of Temperature on Oxidative Stress Biomarkers in Juvenile Chinese Sturgeon (Acipenser Sinensis) under Laboratory Conditions

Temperature is known to affect both the structural and functional properties of proteins in ectothermic animals like fish. Habitat temperature can lead to oxidative stress and influence the metabolic rates of enzymes in fish. In the current study, juvenile Chinese sturgeon (Acipenser sinensis), an anadromous and threatened species that lives only in the Yangtze River, were cultured under laboratory conditions for 66 days at 15, 20, 25, and 30 °C. We then studied the effects of temperature on the oxidative stress biomarkers in juvenile Chinese sturgeon. We found the activity of lysozyme (LSZ) reached its maximum at 25 °C (30.1 ± 1.2 μg/mL), while it reached its minimum at 15 °C (13.1 ± 3.3 μg/mL). In addition, the activity of xanthine oxidase (XOD) reached its maximum at 30 °C (15.20 ± 3.50), while it reached its minimum at 25 °C (12.01 ± 1.66 U/L). Furthermore, both the ability of inhibiting hydroxyl radicals (AIHR) and total antioxidative capacity (T-AOC) were increased at first and subsequently decreased with increasing temperatures, and both reached their maximum at 20 °C (1344.9 ± 349.2 U/mL and 9.54 ± 0.36 U/mL, respectively). Both AIHR and T-AOC were significantly higher at 20 °C than their corresponding levels at 25 °C and 30 °C. These results indicate that the temperature stress was higher at 15 °C and 30 °C for juvenile Chinese sturgeon. Based on the exhibited levels of LSZ, XOD, AIHR, and T-AOC in fish, we conclude the temperature range of 20−25 °C caused the least stress on the fish, and should be considered as the appropriate growth temperature for juvenile Chinese sturgeon.

Effects of extracellular environment factors on the motility in Japanese eel spermatozoa.

We have examined the effects in vitro of the ionic composition, pH and temperature on the motility by the spermatozoa of the Japanese eel (Anguilla japonica). Milt was obtained from 10 males that had been artificially matured by repeated injections of hCG. Sperm motility was monitored with a VHS video recorder and a video camera connected to a microscope. The results showed that most of the sperm were highly motile in 250–700 mM NaCl, 250–650 mM KCl and 350–550 mM CaCl2 solution. The longest duration of sperm motility recorded in 500 mM NaCl, 250 mM KCl and 350 mM CaCl2 solution. Sperm was not motile when suspended at pH 2, sperm motility was observed at pH 3, there was a relatively higher percentage of motile sperm in solutions at pH 4–12 (above 80%). The motility and duration increased within 18–24°C and decreased at the range of 24–30°C. Appropriate K+ ion concentration in the active medium could enhance the percent motility and duration of eel spermatozoa.