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1.
Turbot fry (10–20 mm) and juveniles (85–110 mm) were transferred directly from 16.0–16.5 C to 1.0 C, 2.5 C, 5.5 C or 8.0 C seawater. The fry were more sensitive to cold water than juveniles. The fry survived for 1 week at 8.0 C but not at 5.5 C, whereas juveniles survived at 5.5 C but not at 2.5 C. Transfer of juveniles to 1.0 C and 2.5 C seawater caused a high mortality, a marked increase in plasma Cl- concentration, decrease in muscle water content, and hyperglycaemia. Acclimation to 5.5 C (juveniles) or 8.0 C (fry and juveniles) markedly reduced the sensitivity to 1.0 C exposure.  相似文献   

2.
This study deals with the influence of temperature on the hatching of eggs of Diplectanum aequans, a branchial ectoparasite of sea bass (Dicentrarchus labrax). At temperatures of 20 °C, 25 C and 30 °C hatching takes place within a few days of laying, whereas at 15 C and 10 C it occurs respectively between the 7th and the 12th day and between the 11th and the 19th day. No hatching has been observed at 5 C. Development is not completely inhibited at 5 C as the eggs can, at least partially, go on maturing and will subsequently hatch as soon as higher temperatures are encountered.  相似文献   

3.
Bighead carp (Aristichthys nobilis Oshima) fry of various ages (11, 18, and 35 days post-hatch) were exposed to the low salinities encountered during the annual intrusion of seawater in Laguna Lake, Philippines. Practical indices of salinity tolerance assessed the effect of a 96 h direct exposure to low salinities (0–16). Mean (MST) and median survival times (MST50) of fry decreased as salinity of rearing medium increased. Younger fry were less able to tolerate exposure to these salinities than their older cohorts. Median lethal salinity after 96 h (MLS) revealed higher tolerance among 35–day old fry (7.6) than 11 (2.3) and 18–day old fry (6.0), demonstrating that survival in saline water depends on their age at initial exposure to low salinities. Mean body weight of 18–day old fry reared in 0 and 2 for 3 and 4 weeks was higher than for those reared in 4 and 6 for the same period. Growth over these periods was inversely related with the range of salinities tested. These results demonstrate that, despite their known stenohalinity, bighead carp fry possess some degree of osmoregulatory capability, allowing them to survive and grow in lakes subjected periodically to saltwater inflow.  相似文献   

4.
Salinity influence on the early stages of the African catfish   总被引：1，自引：0，他引：1  
Experiments were conducted to determine the effect of various incubation salinities on the hatching and survival of eggs and hatched fry respectively of the African catfish (Clarias gariepinus). The optimal salinity for the hatching of the eggs ranged from 0–5. Above 5, hatching was significantly low and no hatching occurred at 8 incubation salinity. Median lethal times (LT50) for fry hatched in 0, 2 and 4 incubation salinities, when abruptly transferred to 10 were 59, 49.5 and 50 h respectively. Similarly, LT50 for fry hatched in 0, 2 and 4 incubation salinities, and abruptly transferred to 12 salinity were 17, 22 and 12.50 h respectively. Increase in incubation salinity of the eggs did not seem to enhance the salinity tolerance of the hatched fry.The gradual (stepwise) increase in salinity of 1 per day of the catfish fry hatched in various incubation salinities (0, 1, 2, 3, 4, 5 and 6) had median lethal salinity values of 8, 8, 8, 10, 10, 11 and 11 respectively. © Rapid Science Ltd. 1998  相似文献   

5.
In order to assess the possibilities of utilizing drainage effluents (salinity range 5.0–12.5), fish culture experiments were carried out. Experiments on polyculture using cow dung (24 000 kg ha–1 y–1) as pond fertilizer were conducted at five different salinity levels (0.3–8.5). Studies have revealed that carp perform well in salinities up to 7.5 and reasonably high fish production has been obtained. Even though the ponds had a high trophic status, higher salinities ( > 7.5) appear to repress fish growth probably due to low dissolved oxygen (DO), high BOD and high NH4-N. Experiments on monoculture of common carp (Cyprinus carpio) conducted at two different salinity levels (0.3–0.9 and 6.0–7.0) using four different organic fertilizers (cow dung at 24 000 kg and 20 000 kg, poultry at 1500 kg, duck at 6000 kg and sheep/goat at 1500 kg ha–1 y–1) have revealed the highest fish growth to be in poultry-treated ponds, followed in decreasing order by duck and sheep/goat wastes. Similar trends in fish production were observed both in fresh- and salt-water ponds. However, fish production was lower in ponds having higher salinities ( > 7.5). Nevertheless, these studies indicated that inland saline waters can be utilized for fish culture. With minor modifications in the existing technology of fish culture in stagnant freshwater fish ponds, animal wastes could be used to fertilize brackishwater fish ponds.  相似文献   

6.
Atlantic salmon (Salmo salar L) postsmolts weighing 150 ± 53 g were exposed to 14–15 mg l–1 TA-N (total ammonia-N) in sea water in 1 m3 tanks for 24h. Blood samples were then taken A) immediately after the fish were netted from the exposure tanks and stunned by a blow to the head; B) 2–20 min after the fish were transferred to 15 l of an anaesthetic solution of metomidate in ammonia-free sea water; or C) 2–20 min after the fish were transferred to 15 l of ammonia-free sea water. Plasma TA-N level was 18% lower in the anaesthetised fish compared to in the fish sampled directly from the exposure tanks (p 0.05), and accordingly 16% lower in the fish transferred to pure sea water although this difference was not significant (p = 0.07). Plasma glucose level was higher in the fish transferred to pure sea water than in the fish receiving the two other treatments (p 0.05), but plasma urea, osmolality, Na+, Cl–, Ca2+ or Mg2+ levels did not vary significantly between the different treatments. Plasma TA-N level increased with time in the fish in the metomidate solution (p 0.02).  相似文献   

7.
Thein vitro secretion of 17,20-dihydroxy-4-pregnen-3-one 20-sulphate (17,20-P-sulphate) and the free steroid 17,20-dihydroxy-4-pregnen-3-one (17,20-P), by rainbow trout (Oncorhynchus mykiss) gonads, in response to gonadotropin (GTH) I and GTH II, were studied during the final stages of sexual maturation. Substantial amounts of 17,20-P-sulphate were produced, by both mature ovaries and testes, indicating considerable 20-hydroxysteroid sulphotransferase (20-HST) activity within these tissues. In the post-ovulatory ovary the level of 17,20-P-sulphate (36.6 ng ml–1) greatly exceeded that of 17,20-P (8.59 ng ml–1). The amount of 17,20-P-sulphate produced in incubations of both mature ovary and testes was unaffected by either GTH I or GTH II treatment at physiological concentrations up to 100 ng ml–1. Similarly, incubations of maturing ovary and testes, treated with GTH I or GTH II, in the presence of added 17,20-P at 100 ng ml–1 of medium, produced levels of 17,20-P-sulphate that were similar to those of the controls. In incubations of mature ovarian follicles at the stages of germinal vesicle breakdown and preovulation, both GTHs significantly stimulated secretion of 17,20-P, although GTH II was always more potent than GTH I. GTH II significantly elevated the levels of 17,20-P in testicular incubations from mature males more than 4-fold relative to GTH I and controls, which did not differ from one another.In conclusion, 20-HST, the enzyme responsible for the sulphate conjugation of 17,20-P, was found to be active in the ovaries and testes of rainbow troutin vitro. However, the levels of this enzyme do not appear to be regulated by either GTH I or GTH II.  相似文献   

8.
Although the mechanism of sex-differentiation in crustaceans has yet to be defined, the androgenic gland (AG) is thought to be the exclusive organ that produces the androgenic hormone (AH) which induces male sexual development. This paper presents results of light and transmission electron microscopy and total protein analysis of androgenic glands from three male morphotypes (orange-claw, orange-blue-claw and blue-claw) of the freshwater prawn, Macrobrachium rosenbergii. Highest protein content (76 µg//AG) was found in the blue-claw morphotype as compared to the orange-blue-claw (45 µg/AG) and the orange-claw morphotype (19 µg/AG). Sodiumdodecyl sulfate polyacrylamide gel electrophoresis (SDS-page) analysis of the cell free extract of the AG from the three morphotypes revealed four polypeptides (16, 18, 23 and 26 Kd) which quantitatively increase from the sexually immature orange-claw to the sexually mature blue-claw morphotype. The 16 and 18 Kd polypeptides could be the AHs.  相似文献   

9.
As part of a series of experiments concerning a possible pheromonal function of steroids and steroid glucuronides excreted by the sex organs of the African catfish,Clarias gariepinus, qualitative and quantitative studies, using GCMS, were carried out to examine the presence of the steroids, that can be synthesized by the ovary during oocyte maturation and ovulation, and of the corresponding steroid glucuronides, in the fluid surrounding the eggs in the ovarian cavity shortly after ovulation.Full mass spectra were obtained of 5-pregnane-3,17-diol-20-one, 5-pregnane-3,17,20-triol, 5-pregnane-3,6,17-triol-20-one, 5-pregnane-3,6,17,20-tetrol, 5-androstane-3,17-diol and 5-androstane-3,17-diol-11-one. After selected ion monitoring the following steroids could be detected by the presence of at least two characteristic ions at the expected retention time: 5-pregnane-3, 17,20-triol, etiocholanolone, 5-dihydrotestosterone, 5-androstane-3,11-diol-17-one, testosterone and estradiol. After treatment with -glucuronidase the following steroids could be determined in a similar way: 5-pregnane-3,17-diol-20-one, 5-pregnane-3,17,20-triol, 5-pregnane-3,17,20-triol, 5-pregnane-3,6,17-triol-20-one, 5-pregnane,3,6,17,20-tetrol, 5-androstane-3,17-diol, etiocholanolone, 5-dihydrotestosterone, testosterone and estradiol.The free steroids 5-pregnane-3,6,17,20-tetrol and 5-pregnane-3,6,17-triol-20-one and the steroid glucuronides of testosterone, 5-dihydrotestosterone and estradiol appeared to be the most abundant of these compounds. The results indicate that very polar steroids and steroid glucuronides, synthesized in the ovary, can be excreted via the ovarian fluid shortly before and during oviposition, and possibly function as sex attractants, inducing reproductive behaviour in male conspecifics.  相似文献   

10.
Two sizes of rainbow trout [170 (4), 91 (3) g] were progressively transferred to seawater in January 1995 using three steps of 9, 20 and 28. Na+-K+-ATPase activity in gills, intestine and kidney, and plasma sodium and magnesium levels were assessed in response to changed external salinity. Gradual transfer to seawater had a stimulatory effect on gill and intestinal Na+-K+-ATPase activities after the transfer to 28, while its activity remained unchanged in the kidney. Plasma sodium content was not modified, while magnesium levels increased in response to increased external salinity. The size-dependent response to seawater transfer described by other authors was not detected in our experiments. The results are discussed in terms of long-term adaptation to seawater.  相似文献   

11.
Rainbow trout ovarian follicles were incubated in vitro with tritiated 17,20-dihydroxy-4-pregnen-3-one (17,20-P; maturation-inducing steroid). Within 18–24 h, 56–66% had been converted to tritiated 17,20-dihydroxy-4-pregnen-3-one 20-sulfate (identification confirmed by HPLC) and 27% had been taken up (absorbed) by the follicles. Addition of 125 ng of cold (non-tritiated) 17,20-P to the incubations caused a decrease in the percentage of [3H]-17,20-P which was sulfated (56% 10%) and an increase in the percentage that was taken up (27% 57%). Seven steroids were tested for their effectiveness in decreasing the sulfation and increasing the uptake of tritiated [3H]-17,20-P. The order of effectiveness was in both cases the same: 17,20-P > cortisol > 11-deoxycortisol > 17,20,21-trihydroxy-4-pregnen-3-one > 17-hydroxy-4-pregnene-3,20-dione > 17-estradiol > testosterone. This indicated that the processes of sulfation and uptake of [3H]-17,20-P were related to each other and led to the hypothesis that, when cold 17,20-P is added to the medium, it reduces the proportion of [3H]-17,20-P which is sulfated and thus allows more free [3H]-17,20-P to enter the ovarian follicles. This hypothesis was supported by the finding that each ovarian follicle had the capacity in vitro to sulfate only ca. 2 ng of [3H]-17,20-P per 18h but a capacity to take up > 500 ng per 18h.Gonadotropin I, Gonadotropin II, forskolin and phorbol-12-myristate-13-acetate (which all have an affect on steroid biosynthesis) did not affect the amount of 17,20-P which was sulfated. Sulfating activity was localized in the thecal cell layer of the follicle. The yolk fraction was shown to be responsible for absorbing the [3H]-17,20-P.  相似文献   

12.
Annual plasma insulin and glucose cycles were studied inDicentrarchus labrax maintained in either seawater (37.8) or brackish water (3.5). In both media, the highest insulin levels were found during the prespawning period (August–November) coincident to increases in weight and a decrease in plasma glucose. During spawning (December–April) and postspawning (May–July) periods, the decrease in insulin occurred at the same time as a reduction in growth and an increase of plasma glucose. Temperature and salinity conditions impeded spawning in the brackish water group, in which a minor weight loss was regained more quickly than in the sea water group; insulin levels were also higher.  相似文献   

13.
The mRNA expression of the LH- and FSH- subunits were measured in nesting and post-breeding male three-spined sticklebacks, Gasterosteus aculetaus, as well as in castrated and sham-operated nesting males. Furthermore, expression of an androgen induced kidney protein, spiggin, and 11-ketotestosterone (11KT) levels, were measured in the castrated and sham-operated males. Nesting males had significantly higher levels of both LH- and FSH- mRNA expression compared to post-breeding males. Furthermore, sham-operated males had significantly higher levels of LH- mRNA and spiggin mRNA expression than the castrated fish. Expression of FSH-, on the other hand, did not differ between castrated and sham-operated males. There were strong positive individual correlations between circulating levels of 11KT on the one hand and expressions of LH- and spiggin mRNA, whereas the correlation between 11KT levels and FSH- mRNA was weak. The negative effect of castration on -LH mRNA indicates that gonadal hormones stimulate this expression, whereas this was not the case for -FSH. The observed decline in -LH expression after the end of the breeding season may be the result of cessation of the gonadal stimulation of the pituitary. On the other hand, it is not likely that this can explain the decline in FSH- expression.  相似文献   

14.
Groups of Arctic charr, Salvelinus alpinus (L.), originating from an anadromous stock, were transferred directly from freshwater to seawater (35 S), from freshwater to brackish water (20 S), or were gradually adapted to seawater over a period of 10 days. A control group was kept in freshwater. Feed intake and growth were then monitored during the following 59 days. Two experiments were carried out, one during winter (December–January) and the other during summer (June–July). Water temperature was maintained at 8 C. All fish had been held under natural photoperiod and temperature conditions from the end of the first feeding period (mid-April) until the experiments were carried out. Rates of growth did not differ between the groups of charr held in fresh- and brackish water, but growth of these groups was better than that of fish reared in seawater. Relationships between individual feed intake (FI) and individual specific growth rates (SGR), within groups were expressed as: ln (SGR+1) = a + ln (FI+1), and regression lines were compared using analysis of covariance. In winter, the regression line for fish transferred directly to seawater had a significantly steeper slope, and a lower elevation, than the lines for fish transferred to brackish water or held in freshwater. Fish transferred gradually to seawater had an intermediate position. In summer, the regressions for all groups were parallel with intercepts in the seawater groups being significantly lower than in the freshwater group. This indicates that the gross feed conversion efficiency (FCE) in Arctic charr was lower in seawater than in freshwater. The results are discussed in relation to digestion, gut function and osmoregulation. yc]Keywords xc]Arctic charr (Salvelinus alpinus (L.)) xc]Feed utilization xc]Salinity xc]Season  相似文献   

15.
Three commercially available fatty acid enrichment emulsions (DC Selco, DC DHA Selco and DC Super Selco) were used to enrich Artemia nauplii fed to seahorse, Hippocampus sp. fry. The emulsions varied in their n-3 highly unsaturated fatty acid (HUFA) composition. Total n-3 HUFA content ranged from 200 to 450mgg-1 between the three emulsions while levels of eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) ranged between 47–220 and 80–190mgg-1, respectively. Survival and growth of seahorses at the end of the 30 day growth trial were greater in treatments receiving enriched Artemia. Seahorses receiving Artemia enriched with DC DHA Selco and DC Super Selco showed significantly (p < 0.05) greater mean survival (71.6 ± 6.0% and 78.3 ± 6.0%, respectively) than those receiving unenriched Artemia (48.3 ± 6.0%). Mean standard length was also significantly greater (p < 0.05) in fry fed DC DHA Selco and DC Super Selco enriched Artemia (20.2 ± 0.3 and 19.7 ± 0.3mm, respectively) compared to those fed unenriched Artemia (18.1 ± 0.3mm). The results show that dietary n-3 HUFA are essential for optimal growth and survival of Hippocampus sp. and, based on the fatty acid compositions of the enriched Artemia used in this study, indicate that the level of dietary DHA supporting optimal growth and survival is greater than 9.3mgDHAg-1 dry weight.  相似文献   

16.
The in vitro effects of several steroids on the maturation of intact white sturgeon (Acipenser transmontanus) ovarian follicles were investigated. At the highest concentration (1024 ng ml–1 for the C21 steroids and 1139 ng ml–1 for the C19 steroids), all of the C21 steroids tested, progesterone (P4), 17-hydroxyprogesterone (17OHP), 17,20-dihydroxy-4-pregnen-3-one (17,20-P), 17,(20,21-trihydroxy-4-pregnen-3-one 20-S), 11-deoxycortisol (S) and cortisol (F), as well as testosterone (T) induced germinal vesicle breakdown (GVBD) at 14 and 22 h. At 6 h, only P4 and 17,20-P induced maturation at the highest concentration (1024 ng ml–1). At 14 and 22 h, 11-deoxycortisol was the most potent steroid inducer of GVBD followed by P4, 17OHP, 17,20-P, and 20-S. The steroid 11-hydroxytestosterone (11OHT) was completely ineffective at all concentrations and exposure times. The C21 steroids induced oocyte maturation at concentrations ranging from 4 to 1024 ng ml–1, whereas T induced GVBD at 225 to 1139 ng ml–1. Calculation of the mean effective concentration that induced 50% GVBD (EC50) from the 22 h incubations revealed the following order of potencies: S > P4 > 17OHP > 17,20-P > 20-S >> F > T. These bioassay results, together with previous findings on the endogenous production of steroids by ovarian follicles from gonadotropin-primed females, indicate that more than one steroid has a biological role in the resumption of meiosis in sturgeon oocytes and provides empirical evidence for P4, 17OHP, S, 20-S, and 17,20-P as maturation-inducing steroids in white sturgeon.  相似文献   

17.
Testosterone, 3,17-dihydroxy-5-pregnen-20-one, 17,20-dihydroxy-4-pregnen-3-one (17,20P) and 5-pregnane-3,17,20-triol were identified as the major metabolites of [3H] 17-hydroxyprogesterone in ovarian incubations of the European catfish Silurus glanis. 17,20P and the reduced triol were present only in ovaries from fish primed with carp hypophysial homogenate (chh) while testosterone yields were significantly higher in controls than in treated fish. 11-Ketotestosterone, 11-hydroxytestosterone and 17,20-dihydroxy-4-pregnen-3-one (17,20P) were identified as the major metabolites of [3H]17-hydroxyprogesterone in in vitro incubations of testes of a spermiating catfish. There was no significant production of conjugates or other water soluble metabolites by either sex. The stimulation of plasma 17,20P, 17,20P and 11-hydroxytestosterone by chh in primed but not control males suggests that the role of these steroids in spermiation should be further examined.  相似文献   

18.
The oxygen solubility coefficient (O2) of several different physiological saline solutions was measured over a broad range of temperatures (0 to 25C). Distilled water had a higher value than a physiological salt solution (similar to Cortland's saline). Plasma expanders (polyvinylpyrrolidone, dextran, albumin) lowered the O2 value of the physiological salt solution. A salt solution with a 4% (w/v) mixture of protein substitute had a lower O2 value than the corresponding 1% mixture. The solubility of oxygen was inversely related to temperature.  相似文献   

19.
In fish, oocyte maturation (resumption of meiosis after completion of vitellogenesis and before ovulation) is triggered by maturation inducing steroids (MIS) which generally appear to be secreted in the ovary in response to stimulation by a pituitary maturational gonadotropin. Converging data from different laboratories show that 17-hydroxy, 20-dihydroprogesterone (17, 20-OH-P) is the principal MIS in salmonoids; but clear identification remains to be done in other taxonomic groups.The experiments reported here in the rainbow troutSalmo gairdneri examine the possible involvement of oocyte cAMP on the mechanism of MIS action. The action of 17, 20-OH-P, on germinal vesicle breakdown (GVBD) in oocytes incubatedin vitro within the follicle, was inhibited by various substances expected to elevate the intraoocyte concentrations of cAMP: cAMP ( 1 mM) or dibutyril cAMP ( 2 mM), phosphodiesterase inhibitors such as theophylline ( 0.2 mM) or 3-isobutyl-1 methylxanthine (IBMX 0.1 mM), adenylate cyclase activators such as cholera toxin (> 100 nM) or forskolin ( 0.03 mM). In fact, the combined action of IBMX (1 mM) and forskolin (0.01 or 0.05 mM)in vitro was to promote accumulation of intraoocyte cAMP within 1 to 5 hours. Oocyte cAMP concentrations exhibited a large variability between different females, depending on the stage of oocyte development; a significant positive correlation between oocyte cAMP concentration and the follicular weight, and a significant negative correlation between oocyte cAMP concentration and the median efficient dose of 17, 20-OH-P for induction of GVBD, were observed. Finally, when intrafollicular oocytes were incubatedin vitro, the addition of a maturation-inducing concentration of 17, 20-OH-P (3×10–6M) induced a significant decrease of oocyte cAMP within the first 10 hours of incubation. These results show that cAMP appears to play a central role in the regulation of oocyte sensitivity to 17, 20-OH-P and in the intraoocyte mechanisms leading to GVBD in trout.These data are discussed together with the few indications available in fish concerning the mechanism of MIS action which can be compared to some extent with the amphibian model.  相似文献   

20.
Roach ovaries converted 17-hydroxyprogesterone to 17,20-dihydroxy-4-pregnen-3-one (17,20P) and to glucuronides of testosterone and 17,20P. Small amounts of 5-pregnane-3- and -3, 17, 20-triols, 7-hydroxy-5-reduced metabolites and 17,20-dihydroxy-4-pregnen-3-one (17,20P) were also formed. Rudd ovaries converted this substrate mainly to 17,20P, 5-pregnane-3- and -3,17,20-triols, 17,20-dihydroxy-5-pregnan-3-one and testosterone glucuronide. The main metabolites of progesterone with both species were 17,20P, 5-pregnane-3,17,20-triol and 7-hydroxy-5-reduced steroids. Rudd ovaries formed, in addition, 17,20-dihydroxy-5-pregnan-3-one from progesterone. The pattern of metabolites was markedly altered when the concentration of substrate was increased from 42ng to 1 µg or 100 µg. At the highest concentration, glucuronides and polar steroids were not detectable, while at low concentrations they accounted for over 50% of the metabolites. 20-Hydroxysteroid dehydrogenase was shown to have a very high capacity, producing 21–47 µg 17,20P from 100 µg 17-hydroxyprogesterone substrate with 200 mg ovarian tissue in 5h.  相似文献   

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