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1.
The effects of the Na+/K+ and Mg2+/Ca2+ ratios in saline groundwaters on Na+-K+-ATPase activity, survival and growth of Marsupenaeus japonicus postlarvae were investigated. The results indicate that the Na+-K+-ATPase activity, survival rate and weight gain of postlarvae were significantly affected by the Na+/K+ and Mg2+/Ca2+ ratios (P < 0.05). The Na+-K+-ATPase activity of postlarvae, in every treatment, changed corresponding to Na+/K+ and Mg2+/Ca2+ ratios, and came to a stable level after 24 h. There was a negative relation between Na+-K+-ATPase activity and Na+/K+ ratio, while there was a positive relation between Na+-K+-ATPase activity and Mg2+/Ca2+ ratio. Compared with seawater (the Na+/K+ and Mg2+/Ca2+ ratios are 27.8 and 4.64 respectively), the Na+-K+-ATPase activity of the Na+/K+ ratio 30 treatment showed no significant difference, while the Mg2+/Ca2+ ratio 4.5 treatment showed distinct difference. The survival rates and weight gain of postlarvae increased markedly when the suitable amount of K+ and Ca2+ was added to test water, and arrived at their maximum in the Na+/K+ ratio 20-30 or Mg2+/Ca2+ ratio 4.5 treatment, having no significant difference compared with normal seawater. Therefore, considering the Na+/K+, Mg2+/Ca2+ ratios and the absolute concentration of Mg2+, Ca2+ in the experimental saline groundwaters applied to Marsupenaeus japonicus farming, it should be modulated to around 30, 4.5 and 1312 mg/l, 291 mg/l, respectively.  相似文献   

2.
为探讨高盐条件下凡纳滨对虾仔虾的耐盐性和免疫响应,进行了为期30 d的生长实验。实验设置4个盐度梯度(40、50、60、65),以盐度30为对照,称量实验起始和结束时仔虾的体质量,计算平均日增重,实验结束时检测体内总ATPase、Na~+-K~+-ATPase、酸性磷酸酶(ACP)、碱性磷酸酶(AKP)、总超氧化物歧化酶(T-SOD)、过氧化氢酶(CAT)活性和溶菌酶(LZM)、丙二醛(MDA)含量。结果显示,高盐能显著抑制凡纳滨对虾仔虾的日增重,盐度40、50、60、65平均日增重分别为对照组的84.53%、60.99%、46.19%、27.71%;存活率随盐度升高而显著降低。随着盐度的升高,仔虾体内Na~+-K~+-ATPase活性缓慢升高,盐度60后趋于稳定。总ATPase活性表现出先小幅下降后稳定的趋势,最终维持在1.4 U/mg prot左右。T-SOD和CAT活性随盐度升高均呈现出先升高后降低的趋势,盐度50时达到峰值;ACP和AKP活性随盐度升高呈上升趋势,不同盐度间差异显著。此外,盐度显著影响凡纳滨对虾仔虾的MDA含量,对LZM含量无显著影响。研究表明,盐度越高,仔虾生长越缓慢,用于渗透调节的能量增加。在一定的盐度范围内,高盐能激发仔虾机体部分非特异性免疫酶活性以适应高盐胁迫。  相似文献   

3.
The Australian freshwater fish, silver and golden perch, are increasingly being used for aquaculture. Addition of salt to water is commonly used in commercial aquaculture to reduce stress attributed to high ammonia concentrations. The activities in gill homogenates of ouabain-sensitive Na+/K+-ATPase and NEM-sensitive ATPases (as a measure of H+-ATPases) of silver and golden perch were measured after maintaining the fish in water containing different salt and ammonia concentrations. Six treatments were applied in a 2 × 3 factorial design: two salt treatments, low salt (LS) of 2.5 g l− 1 and high salt (HS) 5 g l− 1, and three ammonia treatments, no added ammonia (NA), low ammonia (LA), 3 mg total ammonia nitrogen (TAN) l− 1 and high ammonia (HA), 5 mg TAN l− 1. In both species, activity of Na+/K+-ATPase was lowest in fish kept in the LSNA treatment (7.4 ± 0.4 μmol Pi mg protein− 1 h− 1 for silver perch and 3.1 ± 0.6 for golden perch) and highest in the HSHA treatment (15.2 ± 1.0 μmol Pi mg− 1 protein h− 1 for silver and 8.4 ± 1.2 for golden perch). In both species there was a significant increase (P < 0.001) in Na+/K+-ATPase activity with increase in salt concentration and with an increase in ammonia concentrations. A significant interaction (P < 0.036) between salt and ammonia on Na+/K+-ATPase activity was observed in silver but not in golden perch. In contrast, the lowest activity for NEM-sensitive ATPase was observed in the HSNA treatment (1.0 ± 0.2 μmol Pi mg− 1 protein h− 1 for silver and 1.5 ± 0.4 for golden perch) and highest in LSHA treatment (2.9 ± 0.4 μmol Pi mg− 1 protein h− 1 for silver and 3.6 ± 1.2 for golden perch). In both species there was a significant decrease in NEM-sensitive ATPase activity with increase in salt concentration and an increase in activity with increase in ammonia (P < 0.003). In silver perch, a significant interaction between the treatments was observed (P < 0.02). The results suggest that in these species of freshwater fish the Na+/K+-ATPase has a role in salt and ammonia homeostasis and that the NEM-sensitive ATPases are more active in fish kept in water with a lower salt content. It is possible that the increase in ammonia resistance when salt is added to the environmental water in commercial aquaculture systems may be due to the effects of salt on gill Na+/K+-ATPase activity rather than the NEM-sensitive ATPases.  相似文献   

4.
The osmoregulation capabilities of juvenile Siberian sturgeon exposed to three experimental osmolalities (22, 250 and 387 mOsmol kg−1) were studied over a 45-day period. Growth performance, haematological parameters, ion concentrations, gill and spiral valve Na+-K+-ATPase activities, as well as gill and spiral valve histology, were measured. At the end of the period, the plasma osmolality of fish kept in 250 and 387 mOsmol kg−1 was higher than that of fish kept in 22 mOsmol kg−1. Similar trends were observed in electrolyte concentrations. Spiral valve and gill Na+-K+-ATPase activity varied with exposure time and environmental salinity. Shortly after being transferred to hyperosmotic media, spiral valve Na+-K+-ATPase activity fell, while gill Na+-K+-ATPase activity remained constant. At the end of the experiment, gill Na+-K+-ATPase activities in fish kept in isosmotic and hyperosmotic media had increased in comparison to those of the control fish. Moreover, spiral valve Na+-K+-ATPase activities recovered and were similar to those recorded in fish kept in hyposmotic environments. Although some of the morpho-physiological mechanisms were operational in juvenile Siberian sturgeon in their adaptation to hyperosmotic media, fish cannot be considered hyperosmotic regulators as they were unable to maintain their plasma osmolality and electrolyte equilibrium in salinities higher than 250 mOsmol kg−1. This suggests that the culture of juvenile Siberian sturgeon in brackish environments is unlikely to be successful. However, our data indicate that in natural environments, juvenile Siberian sturgeon in migratory populations (Ob and Lena Rivers) would be able to migrate successfully into estuarine brackish grounds with a salinity of up to 9%. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

5.
Boleophthalmus boddaerti submerged in 10%, 50% and 80% seawater (sw) for 7 days, had whole body transepithelial potentials (TEP) of 3.3, 18.3 and 22.9 mV, respectively. Hypophysectomy significantly decreased the TEP ofB. boddaerti and reversed the polarity of the TEP of the fish exposed to 10% sw.Hypophysectomy also significantly decreased the branchial Na+-K+ activated adenosine triphosphatase (Na+,K+-ATPase) activity but increased the activity of branchial HCO3 -Cl stimulated adenosine triphosphatase (HCO3 ,Cl-ATPase) inB. boddaerti exposed to 10% sw. However, survival in 10% sw was not significantly impaired by hypophysectomy and no significant change in plasma osmolality and plasma Na+ and Cl concentrations was observed.Various doses of ovine-prolactin or salmon-prolactin were unable to restore the TEP of hypophysectomizedB. boddaerti in 10% sw to that of the sham-operated fish. However, cortisol increased TEP to a positive value in hypophysectomizedB. boddaerti, though it was still lower than the sham-operated control. Cortisol treatment also affected the plasma osmolality, plasma Na+ and Cl contents and branchial Na+,K+-ATPase and HCO3 ,Cl-ATPase activities. Overall, the hormonal control of osmoregulation inB. boddaerti appeared to differ from that of other teleosts.  相似文献   

6.
Growth and energy budget of juvenile cobia (initial body weight ∼ 22 g) at various temperatures (23, 27, 31 and 35 °C) were investigated in this study. Maximal ration level (RLmax, %/day) increased as temperature (T, °C) increased from 23 °C to 31 °C but decreased at 35 °C, described as a quadratic equation: RLmax = −0.023T2 + 1.495T − 17.52. Faecal production (f, mg g− 1 day− 1) increased with increased temperature (T, °C), described as a power function: lnf = 0.738lnT − 0.806. As temperature increased, feed absorption efficiency in dry weight (FAEd, %), protein (FAEp, %) and energy (FAEe, %) all increased first and then decreased, but the variation of feed absorption efficiency was small, with ranges of 89.59-91.08%, 92.91-94.71%, 93.92-95.32%, respectively. Specific growth rate in wet weight (SGRw, %/day), dry weight (SGRd, %/day), protein (SGRp, %/day) and energy (SGRe, %/day) showed a domed curve relative to temperature (T, °C), described as quadratic equations: SGRw = − 0.068T2 + 3.878T − 50.53, SGRd = − 0.079T2 + 4.536T −59.64, SGRp = − 0.084T2 + 4.783T − 63.08 and SGRe = − 0.082T2 + 4.654T − 60.99, and SGRw, SGRd, SGRp and SGRe maximized at 28.5 °C, 28.6 °C, 28.4 °C, 28.5 °C, respectively, as calculated from the regression equations. The relationships between feed conversion efficiency in wet weight (FCEw, %), dry weight (FCEd, %), protein (FCEp, %), energy (FCEe, %) and temperature (T, °C) also took on a domed curve described as quadratic equations: FCEw = − 0.726T2 + 39.71T − 473.8, FCEd = − 0.276T2 + 15.31T − 190.6, FCEp = − 0.397T2 + 22.05T − 277.9 and FCEe = − 0.350T2 + 19.39T − 239.9, and FCEw, FCEd, FCEp and FCEe maximized at 27.4 °C, 27.8 °C, 27.7 °C and 27.7 °C, respectively, as calculated from the regression equations. Energy budget of juvenile cobia fed satiation was 100C = 5F + 67(U + R) + 28G at water temperature 27 °C and 100C = 5F + 70(U + R) + 25G at water temperature 31 °C, where C is food energy, F is faeces energy, (U + R) is excretion energy and metabolism energy, and G is growth energy.  相似文献   

7.
An increase in salinity of freshwater can affect the physiology and metal uptake in fish. In the present study, Nile tilapia Oreochromis niloticus were exposed to copper (1.0 mg/l) in increased salinities (2, 4, and 8 ppt) for 0, 1, 3, 7, and 14 days. Following the exposures, the activities of Na+/K+-ATPase, Mg2+-ATPase, and Ca2+-ATPase were measured in the gill, kidney, and intestine to evaluate the changes in osmoregulation of fish. Results showed that increases in salinity and Cu exposure of fish significantly altered the ATPase activities depending on the tissue type, salinity increase, and exposure durations. Salinity-alone exposures increased Na+/K+-ATPase activity and decreased Ca2+-ATPase activity. Na+/K+-ATPase activity decreased following Cu exposure in 2 and 4 ppt salinities, though the activity increased in 8 ppt salinity. Ca2+-ATPase activity decreased in the gill and intestine in all salinities, while the activity mostly increased in the kidney. However, there were great variations in Mg2+-ATPase activity following exposure to salinity alone and salinity+Cu combination. Cu accumulated in the gill and intestine following 14 days exposure and accumulation was negatively correlated with salinity increase. Data indicated that ATPases were highly sensitive to increases in salinity and Cu and might be a useful biomarker in ecotoxicological studies. However, data from salinity increased freshwaters should carefully be handled to see a clear picture on the effects of metals, as salinity affects both metal speciation and fish osmoregulation.  相似文献   

8.
The mudskipperB. boddaerti, was able to survive in waters of intermediate salinities (4–27). Fish submerged in dechlorinated tap water suffered 60% mortality by the fifth day while 60% of those in 100% sea-water (sw) died after the third day of exposure. After being submerged in 50% or 80% sw for 7 days, the plasma osmolality, plasma Na+ and Cl concentrations and the branchial Na+ and K+ activated adenosine triphosphatase (Na+,K+-ATPase) activity were significantly higher than those of fish submerged in 10% sw for the same period. However, the activities of the branchial HCO3 and Cl stimulated adenosine triphosphatase (HCO3 ,Cl-ATPase) and carbonic anhydrase of the latter fish were significantly greater than those of the former. Such correlation suggests that Na+,K+-ATPase is important for hyperosmotic adaptation in this fish while HCO3 -Cl-ATPase and carbonic anhydrase may be involved in hypoosmotic survival.  相似文献   

9.
A study was performed on the effects of bilateral eyestalk ablation on signal transduction pathways of ion regulation of Litopenaeus vannamei. The study included three treatments (starvation group, bilateral eyestalk ablation, and starvation and bilateral eyestalk ablation) in addition to a control group. The shrimp were sampled at 0, 12, 24, and 48 h. Results showed that the ablation of bilateral eyestalk had significant effects on the contents of three kinds of biogenic amines (BAs), cyclic guanosine monophosphate (cGMP), and the activities of three kinds of ion‐transport enzymes (P < 0.05). According to these results, bilateral eyestalk ablation had significant effects on the ion signal pathway of L. vannamei. The same changes were observed in 5‐hydroxytryptamine (5‐HT) contents, Na+‐K+‐ATPase, and HCO3?‐ATPase activities, suggesting that crustacean hyperglycemic hormone (CHH) regulated the changes in ion‐transport enzymes, mediated by BAs and cGMP. The specific pathways may be 5‐HT → cGMP → Na+‐K+‐ATPase, HCO3?‐ATPase, and BAs → cGMP → V‐ATPase. 5‐HT contents, Na+‐K+‐ATPase, and HCO3?‐ATPase activities in the starvation group were ultimately higher than those in the bilateral eyestalk ablation group, while the cyclic adenosine monophosphate (cAMP) contents increased slightly. Study results suggested that under the situation of bilateral eyestalk ablation, the shrimp could also use feed or its metabolites to increase 5‐HT or cAMP contents to regulate the Na+‐K+‐ATPase and HCO3?‐ATPase activities in gills.  相似文献   

10.
The effect of seawater acclimation and adaptation to various salinities on the energetics of gill and kidney of Atlantic salmon (Salmo salar) was examined. Smolts and non-smolts previously reared in fresh water were exposed to a rapid increase in salinity to 30 ppt. Plasma osmolarity, [Na+], [Cl], [K+] and [Mg++] increased in both groups but were significantly lower in smolts than non-smolts. Gill Na+, K+-ATPase specific activity, initially higher in smolts, increased in both groups after 18 days in seawater. Kidney Na+, K+-ATPase specific activity was not affected by salinity in either group. Gill and kidney citrate synthase specific activity was not affected by seawater exposure in smolts but decreased in non-smolts. In a second experiment, Atlantic salmon smolts reared in fresh water were acclimated to 0, 10 or 30 ppt seawater for 3 months at a temperature of 13–14°C. Gill Na+, K+-ATPase was positively correlated with salinity, displaying 2.5- and 5-fold higher specific activity at 10 and 30 ppt, respectively, than at 0 ppt. Kidney Na+, K+-ATPase specific activity was not significantly affected by environmental salinity. Citrate synthase and cytochrome c oxidase specific activities in gill were slightly (6–13%) lower at 10 ppt than at 0 and 30 ppt, whereas kidney activities were lowest at 30 ppt. Oxygen consumption of isolated gill filaments was significantly higher when incubated in isosmotic saline and at 30 ppt than at 0 ppt, but was not affected by the prior acclimation salinity. The results indicate that although high salinity induces increased gill Na+, K+-ATPase activity, it does not induce substantial increases in metabolic capacity of gill or kidney.  相似文献   

11.
12.
Gill Na+-K+ ATPase and carbonic anhydrase activities were measured, on a fortnightly basis, from February to July, in 0+ age Atlantic salmon (Salmo solar), hatched and reared in a freshwater experimental station in Covas, northern Portugal. Plasma osmolarity and ionic composition were also measured. Gill Na+-K+ ATPase activity increased slowly until April (15–19 moles Pi mg prot–1 h–1). From April to late May there was a great increase in activity (19–32 moles Pi mg prot–1 h–1) followed by a sharp decline in June (15 moles Pi mg prot–1 h–1). In contrast, carbonic anhydrase activity decreased significantly from early April to early June (170-70 moles p-nitrophenol mg prot–1 h–1) and increased in late June, suggesting the existence of a compensatory mechanism for the changes in Na+-K+ ATPase activity. Plasma osmolarity and sodium concentration showed lower levels during the period of high ATPase activity. On the other hand, plasma calcium concentrations showed an increase during the same period (3.47–5.98 mm1–1 of plasma). A transitory decrease in osmolarity and plasma sodium and chlorine concentrations occurred in March, prior to the surge in Na+-K+ ATPase activity, suggesting that the physiological changes, characteristic of parr-smolt transformation can be a consequence of this loss of freshwater osmoregulatory capacity.  相似文献   

13.
The capacity of cortisol, ovine growth hormone (oGH), recombinant bovine insulin-like growth factor I (rbIGF-I) and 3,3,5-triiodo-l-thyronine (T3) to increase hypoosmoregulatory capacity in the euryhaline teleost Fundulus heteroclitus was examined. Fish acclimated to brackish water (BW, 10 ppt salinity) were injected with a single dose of hormone suspended in oil and transferred to seawater (SW, 35 ppt salinity) 10 days post-injection. Fish were sampled 24 h after transfer and plasma osmolality and gill Na+, K+-ATPase activity were examined. Transfer from BW to SW induced significantly increased plasma osmolality but not gill Na+, K+-ATPase activity. Cortisol (50 g g–1 body weight) improved the ability to maintain plasma osmolality and to increase gill Na+, K+-ATPase activity. oGH (5 g g–1 body weight) also increased hypoosmoregulatory ability and gill Na+, K+-ATPase activity. A cooperation between oGH and cortisol was observed in increasing hypoosmoregulatory ability but not in increasing gill Na+, K+-ATPase activity. rbIGF-I (0.5 g g–1 body weight) alone was without effect in increasing salinity tolerance or gill Na+, K+-ATPase activity. rbIGF-I and oGH showed a positive interaction in increasing salinity tolerance, but not gill Na+, K+-ATPase activity. Treatment with T3 (5 g g–1 body weight) alone did not increase salinity tolerance or gill Na+, K+-ATPase activity, and there was no consistent significant interaction between cortisol and T3 or between GH and T3. The results confirm the classical role of cortisol as a seawater-adapting hormone and indicate an interaction between cortisol and the GH/IGF-I axis during seawater acclimation of Fundulus heteroclitus.  相似文献   

14.
盐度胁迫对三疣梭子蟹鳃Na+/K+-ATPase酶活的影响   总被引:2,自引:2,他引:0  
江山  许强华 《水产学报》2011,35(10):1475-1480
通过钼蓝法测定三疣梭子蟹在3组实验盐度的胁迫过程中第2对和第6对鳃Na+/K+-ATPase酶活的变化,比较了3组实验盐度胁迫1 d时,鳃Na+/K+-ATPase的酶活大小。结果表明,在盐度胁迫初期,3组实验盐度下第2对和第6对鳃Na+/K+-ATPase的酶活下降;之后,各组实验盐度下第2对和第6对鳃Na+/K+-ATPase的酶活开始随胁迫时间增长而上升;最后,各组实验盐度下第2和第6对鳃Na+/K+-ATPase的酶活下降并趋于稳定。另外,胁迫1 d时,各组实验盐度下三疣梭子蟹前5对鳃Na+/K+-ATPase的酶活显著低于后3对鳃Na+/K+-ATPase的酶活。三疣梭子蟹对盐度变化的调节可分为被动应激期(酶活力下降)、主动调节期(酶活力逐渐上升)和适应期(酶活力稳定);三疣梭子蟹后3对鳃是离子转运、渗透压调节的主要部位。  相似文献   

15.
Giant freshwater prawns, Macrobrachium rosenbergii (17.9 ± 2.7 g), exposed to different concentrations of saponin at 0, 0.3, 0.6, 0.9 and 1.2 mg l− 1 for 168 h were examined for osmolality, electrolyte levels, oxyhemocyanin, protein levels, acid-base balance status, total hemocyte count (THC), phenoloxidase activity, and respiratory bursts. Hemolymph oxyhemocyanin, protein, and pO2 were inversely related to the saponin concentration. Hemolymph oxyhemocyanin, protein, pO2, pCO2, and pH of prawns exposed to 1.2 mg l− 1 saponin were significantly lower than those of prawns exposed to 0.3 mg l− 1 and control solutions. However, no significant difference was observed in osmolality or electrolyte levels of prawns exposed to different concentrations of saponin for 168 h. The THC of prawns following 168 h of exposure to 0.9 and 1.2 mg l− 1 saponin increased, but the phenoloxidase activity decreased suggesting that the decrease in phenoloxidase activity under saponin stress was not a consequence of the increase in THC. We concluded that saponin at as low as 0.9 mg l− 1 decreases the respiratory protein level and acid-base balance, and modulates the immune system of M. rosenbergii.  相似文献   

16.
The spider crab Maja brachydactyla is overexploited on the NW coast of Spain. Aquaculture of this species can be the solution to the problem, and consequently, several attempts of intensive larval rearing have been conducted. However, most of the studies already published do not provide enough zoo technical data, especially in terms of larval and prey densities or the nutritional quality of diets used for rearing.Three experiments were carried out to evaluate the conditions for intensive larval rearing of M. brachydactyla. Larval stocking density (10, 50 and 100 larvae L− 1), prey:larva ratio (15, 30 and 60 enriched Artemia larva− 1) and diet (enriched Artemia, non-enriched Artemia and polychaete supplement) effects on growth and survival of this species were studied. For larval culture nine, 35 L, 150 μm mesh-bottomed PVC cylinders (triplicates for each treatment and larval stage) connected to a recirculation unit, were used. Temperature and salinity were kept constant at 18 °C and 36‰ respectively. A 12 to 18 day trial was conducted for each experiment and samples of larvae were collected at each larval stage (zoea I, zoea II, megalopa) in the inter-molt phase and at first juvenile. Survival, carapace length and width, dry weight (DW), and proximate biochemical content (protein, carbohydrates and total lipid) as well as lipid class composition were determined.Stocking densities of 100 larvae L− 1 resulted in higher growth in DW and higher content in lipids and protein for zoea I (ZI) and zoea II (ZII) than 10 larvae L− 1. However, survival decreased with increasing stocking density.The use of 60 preys larva− 1 produced larvae with significantly higher DW and protein content, especially at ZII stage, than lower prey densities. Survival rate obtained feeding 60 preys larva− 1 up to the megalopa stage was almost two-fold (42.2%) the rate obtained using 15 preys larva− 1 (24.8%).Larvae fed on enriched Artemia (EA) showed an increase in weight up to megalopa (518.9 ± 26.5 μg) in contrast to larvae fed on non-enriched prey (A) (467.9 ± 6.9 μg). Variation in DW correlated with the total lipid content (L) of the larvae (LEA = 70.1 ± 37.5 μg ind− 1; L= 28.9 ± 3.2 μg ind− 1) especially in terms of neutral lipids. The use of an initial density of at least 50 larvae L− 1 and 60 enriched Artemia larva− 1 can be considered the most adequate rearing parameters in order to obtain good results in growth and survival of M. brachydactyla.  相似文献   

17.
Several experiments were performed to investigate the physiology of seawater acclimation in the striped bass, Morone saxatilis. Transfer of fish from fresh water (FW) to seawater (SW; 31–32 ppt) induced only a minimal disturbance of osmotic homeostasis. Ambient salinity did not affect plasma thyroxine, but plasma cortisol remained elevated for 24h after SW transfer. Gill and opercular membrane chloride cell density and Na+,K+-ATPase activity were relatively high and unaffected by salinity. Average chloride cell size, however, was slightly increased (16%) in SW-acclimated fish. Gill succinate dehydrogenase activity was higher in SW-acclimated fish than in FW fish. Kidney Na+, K+-ATPase activity was slightly lower (16%) in SW fish than in FW fish. Posterior intestinal Na+,K+-ATPase activity and water transport capacity (Jv) did not change upon SW transfer, whereas middle intestinal Na+,K+-ATPase activity increased 35% after transfer and was correlated with an increase in Jv (110%). As salinity induced only minor changes in the osmoregulatory organs examined, it is proposed that the intrinsic euryhalinity of the striped bass may be related to a high degree of “preparedness” for hypoosmoregulation that is uncommon among teleosts studied to data.  相似文献   

18.
The current study investigated acute toxicity to ammonia of the South African abalone, Haliotis midae, from three size classes relevant to mariculture operations, and the chronic impact of sub-lethal ammonia levels on growth of juvenile abalone.Results showed that tolerance to ammonia (at pH 7.8 and Ta = 15 °C) increases with body size (i.e. age) as indicated by 36 h LC50 values: juvenile abalone (1-2.5 cm shell length) had the lowest LC50 of 9.8 μg l− 1 FAN, whereas LC50 was 12.9 μg l− 1 FAN in “cocktail”-size abalone (5-8 cm shell length). The highest LC50 of 16.4 μg l− 1 FAN was observed in “brood stock”-size animals (10-15 cm). When “cocktail”-size abalone were allowed to acclimatize to sub-lethal ammonia levels for 48 h, their ammonia tolerance increased compared with non-acclimatized abalone of the same size: LC50 was 2.0 μg l− 1 FAN higher at 14.8 μg l− 1 FAN.Growth of juvenile abalone (1-2.5 cm shell length) during chronic exposure to sub-lethal FAN levels is inhibited: specific growth rate (SGR) is significantly reduced by 58.7% to 0.10 ± 0.03% d− 1 (weight) compared with 0.24 ± 0.06% d− 1 of abalone of a control group (no ammonia).The results demonstrate the negative effects of ammonia not only on survival but also on growth of farmed abalone, both impair profitability of the farming operation. The information from the present study will be helpful in determining water quality requirements in South African abalone farms.  相似文献   

19.
In three separate experiments, harpaticoid copepods Tisbe monozota (alive and dead) and a microparticulate microbound diet were evaluated as alternatives to live Artemia nauplii as food, beginning at either stage PZ2 or M1, in the larval culture of Litopenaeus vannamei. Larvae were cultured in 2 L round bottom flasks at a density of 150 L− 1 (Experiment 1) and 100 L− 1 ( 3.2 and 3.3) at 28 °C, 35‰ salinity and 12:12 LD photoperiod, and fed 4×/day- 1. Larvae were initially fed a mixture of phytoplankton to stages PZ2 or M1 and then fed either live Artemia, live or dead copepods, or a microparticulate microbound diet. The experiments were terminated and all larvae were harvested when more than 80% of larvae had molted to postlarvae 1 (PL1) within any flask representing any of the treatments. The comparative value of the different diets and feeding regimes was determined by mean survival, mean dry weight and total length of individual larva, and percentage of surviving larvae that were PL1. Trypsin activity of samples of larvae from each treatment was also determined. The microparticulate microbound diet effectively served as a complete substitute for Artemia nauplii when fed beginning at stage M1. When fed at the beginning of the PZ2 stage, survival was comparable to that of larvae fed Artemia, but mean dry weight, mean total length, and percent of surviving larvae that were PL1 generally were significantly less. Responses to the feeding of copepods, whether fed dead or live, as a substitute were generally significantly less than those of larvae fed either the Artemia nauplii or the microparticulate diet. Values of trypsin activity (10− 5 IU/μg- 1 dry weight) corresponded to the relative proportions of the different larval stages within a treatment, with higher activity being characteristic of early stages. Previously demonstrated successful results with another species of crustacean suggest that the microparticulate microbound diet has characteristics that should be effective in the culture of the carnivorous stages of other crustacean and fish larvae that are currently fed live Artemia nauplii.  相似文献   

20.
陶易凡  强俊  王辉  徐跑  马昕羽  赵文强 《水产学报》2016,40(11):1694-1704
研究了高pH胁迫对克氏原螯虾鳃、肝胰腺中酶活性的变化,以及对鳃、肝胰腺组织结构的影响。在得出96 h L C_(50)的基础上,设置对照(pH7.6)和实验(pH10.2)2个pH处理组,进行96 h高pH胁迫,于胁迫后0、2、8、24和96 h测定鳃Na~+-K~+-ATP酶、乳酸脱氢酶(lactate dehydrogenase,LDH)、延胡索酸还原酶(fumarate reductase,FRD)、肝胰腺超氧化物歧化酶(superoxide dismutase,SOD)、过氧化氢酶(catalase,CAT)的活性以及丙二醛(malondialdehyde,MDA)的含量,并采集完整的鳃、肝胰腺做组织切片观察。结果发现,96 h LC50 pH值为10.194。高pH应激后,实验组鳃Na+-K+-ATP酶、LDH和FRD的活性呈上升趋势,pH胁迫8 h后与对照组差异显著(P0.05);随胁迫时间的延长,实验组肝胰腺MDA含量的变化趋势与LDH和FRD相似,CAT活性呈先上升后下降趋势,SOD活性起初变化不大,pH胁迫24 h后出现明显下降(P0.05)。鳃和肝胰腺的组织观察表明,随着pH胁迫时间的延长,鳃呼吸上皮细胞逐渐脱落,角质层受损、破裂,鳃叶受损程度逐渐加剧;肝胰腺小管基膜破损,小管内空泡增多、体积增大,肝细胞细胞数量减少。研究表明,高pH胁迫对克氏原螯虾代谢会产生影响,同时导致氧化应激,并会对鳃和肝胰腺的组织结构造成损伤,影响其生物学功能。  相似文献   

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