Guangpeng Feng

The bioaccumulation of fluoride ion (F(-)) in Siberian sturgeon (Acipenser baerii) under laboratory conditions.

A 90-d growth trial was conducted to determine the accumulation of fluoride ions (F(-)) in juvenile Siberian sturgeon (Acipenser baerii). Fish were exposed to nominal F(-) concentrations of 4, 10, 25, 62.5 mg L(-1) (added as NaF), along with a control group. Fish growth was determined and F(-) concentrations in bone, cartilage, skin, gill, muscle, liver, gut and pylorus were analyzed by fluoride specific electrode method. Fish growth was inhibited for groups exposed to 10, 25, and 62.5 mg F(-) L(-1) compared to the control group. Significant increases in F(-) concentrations were observed in bone, cartilage, skin and gill of Siberian sturgeon exposed to 4 mg F(-) L(-1). The highest F(-) concentration was in bone (3204.4 mg kg(-1), dry weight), followed by cartilage (1401.2 mg kg(-1)), gill (389.4 mg kg(-1)), skin (100.1 mg kg(-1)). Muscle, liver, gut and pylorus did not show increasing accumulation with increasing F(-) levels in the water, but liver, gut, pylorus accumulated higher F(-) concentration compared to muscle. It is summarized that F(-) accumulates mainly in bone and cartilage in Siberian sturgeon, with 10 mg F(-) L(-1) in water harmful to growth. Even 4 mg F(-) L(-1) may be harmful to Siberian sturgeon growth during a long-term waterborne exposure.

Osmotic and ionic regulation and Na+/K+-ATPase, carbonic anhydrase activities in mature Chinese mitten crab, Eriocheir sinensis H. Milne Edwards, 1853 (Decapoda, Brachyura) exposed to different salinities

Mature Chinese mitten crabs, Eriocheir sinensis H. Milne Edwards, 1853, are exposed to brackish water or seawater as an obligatory part of their reproductive migration. We investigated the changes in haemolymph osmolality, haemolymph Na+, Cl−, Ca2+ and K+ concentrations, as well as gill Na+/K+-ATPase and carbonic anhydrase activity in both mature females and males, when in freshwater (0.3‰ salinity, 8 mOsm (kg H2O)−1) and after step-wise acclimation to salinities ranging from 7 to 35‰ (175-1044 mOsm (kg H2O)−1). Both females and males strongly hyper-regulated their haemolymph osmolality over a salinity range of 0.3-21‰, the isosmotic point approaching 28‰ salinity, and slightly hypo-regulated at 35‰ salinity. Haemolymph Na+ and Cl− levels correlated positively with haemolymph osmolality. Ca2+ and K+ levels, however, were maintained at a relatively narrow range and showed a contrary trend in their response to salinity. This indicated that Na+ and Cl− are the main contributors to increasing haemolymph osmolality. Reduced Na+/K+-ATPase and carbonic anhydrase activity in the posterior gills at elevated salinity suggests a direct physiological response to a decrease of Na+ intake. No sexual differences existed for all parameters except for significantly higher haemolymph Ca2+ and K+ levels and CA activity in females than in males at some salinity levels. It is suggested that mature Eriocheir sinensis is a strong hyper-osmoregulator but a weak hypo-osmoregulator. No sexual differences appeared to exist in osmotic and ionic regulation of mature Eriocheir sinensis exposed to different salinities.

Effects of different vitrificant solutions on the embryos of the Chinese mitten crab Eriocheir sinensis (Decapoda, Brachyura)

Vitrification could provide a promising tool for the cryopreservation of embryos. However, in order to achieve a vitrifiable medium, a high concentration of permeable cryoprotectants must be used, and the incorporation of high-molecular-weight compounds should also be considered. In the present study, the toxicity of six vitrificant solutions was determined in Eriocheir sinensis H. Milne Edwards, 1853 embryos at five developmental stages (cleavage, blastula, gastrula, eyed stage and heart beating stage). Six vitrifying solutions were prepared with seawater of salinity 15 and the cryoprotectants propylene glycol (PG), methanol (MeOH), dimethyl sulfoxide (DMSO) and dimethylformamide (DMF) in different proportions (A: 30% PG + 20% DMF; B: 30% MeOH + 20% DMF; C: 30% PG + 20% MeOH; D: 30% PG + 10% MeOH + 10% DMF; E: 20% DMSO + 30% PG; F: 20% DMSO + 30% MeOH). The impact of each of these solutions on E. sinensis embryos was then assessed and compared. Vitrifying solution “A” produced the highest survival rate, albeit lower than that of the control. A five-step equilibration of embryos in all six vitrifying solutions resulted in higher survival rates than equilibration in 3 or 2 steps. The tolerance of E. sinensis embryos to the vitrifying solutions increased with embryonic maturity, cleavage and blastula stage embryos being very sensitive to vitrifying solutions, and a two-step equilibration of embryos in the six vitrifying solutions resulted in no survival at all. Embryos in the eyed stage and heart beating stage showed a higher tolerance to vitrifying solutions as compared to the other stages, with the survival rates achieved over 50% and 60%, respectively. Cleavage stage and gastrula stage embryos did not survive after cryopreservation, although we acquired a percentage of transparent embryos (generally an indication of successful cryopreservation). Fifteen viable embryos were eventually recovered from 361 freeze-thawed embryos, all from eyed stage and heart beating stage embryos. One larva with apparently normal morphology hatched successfully from those 15 embryos.

Substrate color preference and feeding by juvenile Chinese sturgeon Acipenser sinensis: exploration of a behavioral adaptation

Experiments were conducted in artificial stream tanks with juvenile Chinese sturgeon, Acipenser sinensis, captured in the Yangtze Estuary to test two null hypotheses (1) juveniles have no preference for white or black substrates, and (2) white or black substrate color has no effect on juvenile feeding efficiency on the barcheek goby,Rhinogobius giurinus, a dark-colored prey of wild juveniles. Juveniles strongly preferred white substrate. However, in feeding tests, feeding efficiency by juveniles was similar on white or black substrates. Thus, substrate color had no effect on feeding efficiency. Results suggest the innate preference for white substrate is not a visual adaptation for capturing prey on a contrasting background, but is an adaptation predisposing juveniles to seek light-colored sandy substrate where forage abundance is greatest.

The relationship between hemolymph biochemical parameters and salinity in female parent Chinese mitten crab(Eriocheir sinensis)

Two salinity concentrations(salinity 12,salinity 25)and a control group of fresh water were set up in the experiment.The samples were respectively taken at 0,3,6,12,24,48,72,96,and 144 h to study the effects of salinity changes on the hemolymph biochemical parameters of the female parent Chinese mitten crab(Eriocheir sinensis).The results showed that the values of total protein(TP)in salinity concentrations were significantly higher than that of the control group during the first 6 hours(P0.05)while the values of TP in two salinity concentrations reached the same level and kept a little higher than that of the control group after 96 hours.The values of glucose(GLU)increased with the increasing of salinity concentration,and the values of GLU both increased first and then declined in the salinity concentrations.The values of GLU in salinity 25 reached the maximum level at 72 h and were significantly higher than that of the other two groups(P0.05).The values of triglycerides(TG)in salinity 12 declined gradually,and were significantly lower than that of control group during 6-144 h(P0.05),yet were significantly lower than that of salinity 25 after 72 h(P0.05).The values of TG in salinity 25 declined first and then increased,and reached the same level as control group after 72 h.The values of alkaline phosphatase(ALP)both increased first and then declined in the two salinity concentrations.The values of lactate dehydrogenase(LDH)in the two salinity concentrations both reached the maximum values at 3 h and reached the minimum at 12 h.The result showed hemolymph TP,GLU,and TG all changed significantly during travelling from fresh water to saline water in parent Chinese mitten crab.It could be concluded that(1) the parent Chinese mitten crab enhanced the process of energy metabolism to deal with the sudden change of salinity and increased the use of lipids and carbohydrates as energy source.(2) the parent Chinese mitten crab first regulated protein metabolism in response to the changes of external osmotic pressure and finally adapted to the high-salinity water.

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.

Distribution of Larval Crabs (Eriocheir sinensis) and Relationship With Oceanographic Features in the Yangtze Estuary

ABSTRACT Eriocheir sinensis, the Chinese mitten crab, has decreased dramatically in the Yangtze Estuary in recent years. Distribution of mitten crab larvae in the Yangtze Estuary and the influence of oceanographic features on their densities were analyzed based the samples collected from 27 stations in March, April and May 2013–2015. Results showed zoeae I and II began to appear in March, zoeae III and IV in April, and zoeae V and megalopae in May. The spatial patterns of zoeae II, III and IV were identified as having a highly clustered distribution. Habitats located near the mouth of the North Branch were mainly hotspots of each stage larvae. Both biotic (zooplankton biomass) and abiotic variables (water temperature and depth) had significant impacts on the larval densities. Compared with 1986–1988, the original nursery habitats have moved approximately 20–50′E towards the shore, and have locally lost the nursery function after the Three Gorges Dam (TGD) construction.

Copper and Zinc Toxicity Estimates for Juvenile Chinese Sturgeon Acipenser sinensis in the Yangtze River Estuary

Acute toxicity estimates of copper (Cu) and zinc (Zn) in juvenile Chinese sturgeon were studied in the Yangtze River estuary and using the static test method to assess Cu and Zn toxicity. The results showed that Cu was more severely toxic to Chinese sturgeon than Zn. The Cu LC50 after 24-, 48-, 72and 96-h exposures to Chinese sturgeon were 0.0606, 0.0414, 0.0289 and 0.0217 mg·L, respectively, whereas these values were 3.590, 2.514, 1.759 and 1.200 mg·L for Zn, respectively. Estimated safe concentrations of Cu and Zn were 0.00217 and 0.1200 mg·L, respectively. However, the Cu and Zn standards for fisheries water quality in China are 0.01 and 0.10 mg·L, respectively. The liver was the major accumulation site for Cu. Cu content in the liver of juveniles in the control group (no Cu) was the highest, followed by the gills, whereas the lowest content was detected in cartilage. The fastest accumulator of Cu was the liver, followed by the stomach, and cartilage and skin had the lowest contents. Superoxide dismutase (SOD) and catalase (CAT) activities in the liver tissues of juveniles were relatively low for the first 24 h, but the activities recovered gradually from 24 to 48 h and decreased after 48 h to levels lower than the contro1 group. These changes in SOD and CAT activities indicate that juvenile Chinese sturgeon were severely affected by Cu. These data show that Chinese sturgeon juveniles face the threat of Cu contamination and this alerts officials to the dangerous situation.

Changes in non-specific immune parameters of mature Chinese mitten crab(Eriocheir sinensis) in response to elevated salinities

Mature Chinese mitten crabs,Eriocheir sinensis,are exposed to brackish water or coastal waters as an obligatory part during adult reproductive migration.In this study,we investigated the changes in serum total protein and oxyhemocyanin contents,alkaline phosphatase(AKP),superoxide dismutase(SOD) and phenoloxidase(PO) activities in both mature male and female E.when in freshwater and after step-wise acclimation to the following salinities: 7,14,21,28,35.Increasing salinities caused a gradual decrease in serum total protein and oxyhemocyanin contents.Serum AKP activity was elevated slightly at 7,thereafter it dropped slowly by the end of experiment.Serum SOD activity showed a slight decrease after increase of salinity until 21,it was activated above 21.Serum PO activity decreased gradually with the increase of salinity in males;however,it maintained a stable level above 21 in females.All tested parameters in serum except for SOD were significantly higher in females than those in males.It is suggested that elevated salinity induced a decrease in serum total protein and oxyhemocyanin contents.Serum immune enzyme activities in mature E.sinensis will be affected when the salinity was near to or above 28,which could exert a negative effect on reproduction.Further studies are needed to understand the biochemical adaptation of mature E.sinensis,during their reproductive migration acclimation to elevated salinities.Sex differences should not be ignored.

Effects of cryopreservation on exterior shape and interior structure of Chinese mitten crab (Eriocheir sinensis) embryos

In order to deeply understand the effects of cryopreservation on the configuration of embryos,we chose the Eriocheir sinensis as the object,and observed the exterior shapes and interior structure of different developmental stages embryos after treatment with cryoprotectants and cryopreservation by means of microscope,slice and electron microscopy.Results showed that:(1) Cleavage embryos swelled clearly after treatment with vitrifying solutions by two-step methods,exterior shape of the embryos had no significant difference compared to the control group by three-step equilibration methods,some yolk overflowed from the inner cells and cells were damaged seriously after cryopreservation.(2) Exterior shape of gastrula stage embryos was similar to the control group after treatment with two-step equilibration methods,surface of gastrula stage embryo treated with cryoprotectants crinkled and shaped reticulation structure by scanning electron microscopy(SEM),white gobbet appeared in cells of embryos and fringe of cell was coarse and protuberant by transmission electron microscopy(TEM).After cryopreservation,color of embryos was pink,cell became opaque,the brim of cell membrane was blurry and shaped floss,segmental yolk was disintegrated into granule,the surface of embryos was sunken and wrinkled.(3) Cell membrane of embryos broke off,ice holes of different size appeared inside embryos,visible vacuoles appeared inside cells by slice observation.Ice holes in cells were very clear and some vacuoles appeared,about 80% mitochondria dissolved,breach of cells was very obvious by TEM.Exterior shape of the original zoea stage embryos had no difference compared to that of the control group after treatment with cryoprotectants by microscope and SEM.After cryopreservation,above 95% tissues shaped dispersion,partial yolk was disintegrated into granule,cell membrane of embryos broke off,ice holes appeared inside embryos.Surface of 90% embryos was sunken and wrinkled,but the cuticle of 10% embryos retained slick and intact by SEM.The results implied that the original zoea stage of embryos was the appropriate stage for cryopreservation.