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1.
Reproduction related immunoglobulin changes in rainbow trout   总被引：4，自引：1，他引：4  
Annual changes in plasma immunoglobulin (IgM) levels were investigated in three strains of rainbow trout Oncorhynchus mykiss which have different spawning periods, i.e., September–October, November–December, and January, reared under constant water temperature and natural day length. Plasma IgM levels decreased during the spawning season in all strains tested. The IgM changes became reversed in response to significant increases in plasma testosterone (T) and estradiol-17 in females and T and 11-ketotestosterone in males. Though the IgM decline showed a connection with suppressed immunocompetence, since many mature fish caught fungal diseases, no clear differences were observed in the plasma IgM levels between infected and noninfected fish during the spawning season. Incidentally, plasma IgM levels in infection prone fish were higher than in noninfection prone fish prior to the spawning season, whereas coincident differences in the plasma steroid levels were observed. Immature fish reared under lower water temperatures showed lower IgM levels. The effect of water temperature may have to be considered when analyzing the defense mechanism during the spawning season in rainbow trout.  相似文献   

2.
Thyroid stimulating hormone (TSH) is a vertebrate pituitary heterodimeric hormone that stimulates the thyroid gland to produce the thyroid hormones, T3 and T4. We report here the cloning, by PCR on reverse-transcribed pituitary RNAs, of a 180 bp fragment of the cDNA encoding TSH subunit in the turbot (Psetta maxima). The deduced amino acid sequence displayed 66 and 75% identity with the corresponding sequence from the European eel (Anguilla anguilla) and the rainbow trout (Oncorchyncus mykiss), respectively. This cDNA was then used as a probe for densitometric analysis of individual pituitary Northern blots. TSH mRNA levels were quantified in turbot where circulating thyroid hormones were modified by dietary treatments or hormone supplementation. Recombinant rainbow trout growth hormone had no effect on circulating thyroid hormone levels or on pituitary TSH mRNA level. In turbot fed heat-treated rapeseed meal, plasma T4 levels were lowered and TSH mRNA increased more than two fold. In contrast, when turbot were fed a standard fish-meal supplemented with T3, circulating T3 levels were elevated and there was a dramatic decrease in TSH mRNA level. It is concluded that both thyroid hormones are able to down-regulate TSH mRNA level in vivo in the turbot. These results are discussed in the context of the evolution of the TH feed-back on TSH production.  相似文献   

3.
Two year old black porgy (Acanthopagrus schlegeli) fed a diet containing 4.0 mg kg–1 of estradiol-17 (E2) for 5 months had significantly lower GSI than the control group during the spawning season. E2 suppressed testicular development, spermiation and plasma testosterone (T) and 11-ketotestosterone (11-KT) and stimulated ovarian development, vitellogenesis and sex reversal. Spermiation in the control group occurred in January and February with the concentrations of 1.08–1.36 × 1010 sperm ml–1 of milt. Higher plasma T and 11-KT, but lower E2 levels were detected in the spermiating fish (control group). Higher plasma E2 levels were detected in the sex reversing black porgy during the pre-spawning season. A sharp rise in plasma 11-KT and a drop in T levels were detected in spermiating fish (control group) from January to February. Plasma 11-KT levels correlated with the testicular development and spermiation. The data suggest that E2 plays an important role in controlling the sex reversal of black porgy.to whom correspondence should be addressed.  相似文献   

4.
11-Ketotestosterone (11-KT) is an important plasma androgen in male African catfish. The quantitatively predominating androgen produced by the testis, however, is 11-hydroxyandrostenedione (OHA). Our working hypothesis to explain this mismatch assumed that OHA is converted to 11-KT at extratesticular sites. First, we examined the in vivo metabolism of [3H]-OHA in mature males after sham-operation or removal of either the testes (TC), the seminal vesicles (SVC), or both (TSVC) by analysing the pattern of circulating [3H]-androgens two hours after intravenous injection of [3H]-OHA. [3H]-OHA was converted to [3H]-11-KT to the same extent in all groups, indicating that neither ablation of testes nor of seminal vesicles, or both attenuates this conversion. We then examined the in vitro metabolism of [3H]-OHA by several types of tissues. Liver and seminal vesicle tissue were found to produce significant amounts of [3H]-11-KT. The conversion capacity in vivo was assessed by injecting TSVC-castrated males with increasing doses of radioinert OHA, followed by the quantification of OHA and 11-KT plasma levels. Saturation of the conversion capacity was not reached but the 11-KT production capacity is at least 80 ng per ml of plasma per hour. Moreover, liver fragments were tested for their OHA to 11-KT conversion capacity in vitro using increasing concentrations of radioinert OHA. The 11-KT producing increased with time and OHA concentration. The production rate was 90 pg 11-KT mg-1 liver h-1. Considering the results of the surgical experiments and the fact that the total hepatic mass by far exceeds that of the seminal vesicles, we conclude that the hepatic conversion is of primary relevance in vivo.  相似文献   

5.
In addition to catalytical assays, immunochemical techniques have recently been employed to measure induction of the cytochrome P-450 (P450) monooxygenase system in fish with polyaromatic hydrocarbons (PAH). In the present study, polyclonal antibodies were raised against rainbow trout P450IA1. Levels of rainbow trout P450IA1 determined using protein blotting- and ELISA procedures were compared with levels of 7-ethoxyresorufin-O-deethylase (7-EROD) activity in liver microsomes from rainbow trout. These comparisons showed that values of P450A1 were positively correlated (r=0.99 and r=0.97) with 7-EROD activities. In addition, the effects of isosafrol (ISF) or -naphthoflavone (NF) treatments on P450 levels in rainbow trout liver were investigated using immunochemical and catalytical methods. ISF treatment induced 7-EROD activity as well as 7-methoxycoumarin-O-demethylase-, 7-ethoxycoumarin-O-deethylase-, 7-propoxy-coumarin-O-depropylase and 7-butoxycoumarin-O-debutylase activities, although to a lesser extent, compared with the NF treatment. In contrast, immunochemical quantification of rainbow trout P450IA1 protein revealed a slightly different pattern. ISF appeared to be a weak inducer of P450IA1 in rainbow trout compared with NF. In addition, the degree of inhibition of 7-alkoxycoumarin-O-dealkylase activities in ISF microsomes differed from that measured in control- and NF microsomes. The discrepancies between catalytic and immunochemical estimates of rainbow trout P450IA1 in ISF treated fish in addition to differencs between specific inhibitory pattern by specific polyclonal antibodies raised against rainbow trout P450IA1, indicate that important differences exists between the responses induced by NF- and ISF treatments in the rainbow trout liver.Part of this work was presented at the 6th International Conference on Biochemistry and Biophysics of Cytochrome P-450, Vienna, Austria, July 3–8, 1988.  相似文献   

6.
Ovarian follicles taken from sexually maturing rainbow trout at the mid-vitellogenic stage of ovarian development were incubated in vitro in the presence or absence of melatonin or somatostatin-14 (SRIF-14) to determine whether there is evidence of a direct action of these factors on gonadal steroidogenesis in fishes. The steroidogenic capacity of the ovarian follicles was assessed by measuring testosterone (T) and 17-estradiol (E2) release into the incubation medium, and by examining the steroid metabolites produced following incubation of follicles with radiolabelled steroid precursors.Melatonin appears to elicit a biphasic effect on steroidogenesis by in vitro rainbow trout ovarian follicles; at a concentration of 1 × 10–3 M, melatonin stimulated basal T and E2 production, but at a concentration of 1 × 10–2 M there was an inhibition of basal and sGtH-stimulated T and E2 Melatonin may act to reduce the activity of specific steroidogenic enzymes, since there was evidence of melatonin at 1 × 10–2 M enhancing the accumulation of [3H]17-hydroxyprogesterone in the medium following incubation with [3H]pregnenolone, possibly suggesting the inhibition of C17,20-lyase activity. In contrast, SRIF-14, used at concentrations of 1 × 10–8 M and 1 × 10–6 M, had no effect on basal or sGtH-stimulated E2 or T production by ovarian follicles, incubated in vitro.  相似文献   

7.
Thein vitro hepatic monodeiodination of L-thyroxine (T4) to triiodo-L-thyronine (T3) in rainbow trout (Salmo gairdneri) was found to be pH- and temperature-dependent, and was related to the amount of homogenate in the reaction vessel, suggestive of an enzyme-regulated event. Dithiothreitol (DTT) introduced into the reaction medium stimulated T3 production in a dose-related manner, whilst 6n-propyl-2-thiouracil (PTU) inhibited T3 production, also in a dose-related manner. The conversion was stimulated in the presence of light and depressed at buffer concentrations of less than 0.1 M.Prior treatment of fish with an intraperitoneal slow-release implant containing 17-estradiol (E2), at doses which are known to induce chronic mild elevations in plasma E2 levels, elicited a biphasic response to E2 as regards hepatic T3 production from T4 with a depression of T4 to T3 conversion evident within 1–2 days after implantation, and a subsequent stimulation of T3 production evident 56 days after, implantation. This increased hepatic deiodinase activity after chronic exposure to E2 at physiological doses was accompanied by a 3.5 fold increase in Vmax without a significant change in Km, suggesting the presence of an increased amount of the enzyme.  相似文献   

8.
Efficacy of mineral oil-based experimental injection vaccines against Flavobacterium psychrophilum were tested in rainbow trout, Oncorhynchus mykiss (Walbaum), under laboratory and field conditions. The vaccines consisted of formalin- or heat-inactivated whole bacterium cell preparations of two different serotypes (Fd and Th) or a combination of serologically different F. psychrophilum (Fd and/or Th and/or Fp(T);Th). Specific antibody responses against the bacterium in plasma and skin mucus were evaluated post-vaccination with enzyme-linked immunosorbent assay. Efficacy of the vaccinations was determined by challenge trials to F. psychrophilum with the vaccinated rainbow trout. Significantly higher antibody levels in plasma were detected in vaccinated fish compared with mock-vaccinated fish. Injection vaccination did not trigger specific antibody production in the skin mucus. Significantly higher survival of i.p. vaccinated fish compared with non-vaccinated fish was observed during the challenge. The results suggest that mineral oil-based injectable vaccines containing formalin- or heat-inactivated virulent cells of F. psychrophilum effectively triggered specific antibody production and protected the fish against bacterial cold water disease.  相似文献   

9.
Mediators and mechanisms responsible for the inhibitory modulation of trout intestinal smooth muscle were examined using a series of putative mediators and substances known to modulate neurotransmission in mammalian systems. Frequency response relationships to transmural stimulation and concentration response relationships to 5-hydroxytryptamine, carbachol, and substance P were established on paired segments of rainbow trout intestinein vitro in the presence and absence of putative modulatory agents. Modulation of neurally-mediated contractions of trout intestine was achieved with dibutyryl cyclic AMP and forskolin, agents that increase intracellular levels of cyclic AMP. The effect appears to be at the level of the smooth muscle, since the adenylate cyclase activator, forskolin, inhibited muscarinic and serotoninergic contractions as well as transmurally stimulated contractions. Substance P-induced contractions were unaffected by forskolin. The endogenous agonists/neurotransmitters which would increase cyclic AMP levels in rainbow trout intestinal smooth muscle are as yet unknown. The effects do not appear to be modulated by vasoactive intestinal peptide (VIP), calcitonin, calcitonin gene-related peptide (CGRP), or agents that activate -adrenoceptors. Prostaglandin E2 (PGE2) and 2-adrenergenic agonists are possible agents which will decrease contractility of the smooth muscle. They were only active in the proximal intestine and on transmurally stimulated contractions. The effects of both PGE2 and 2-agonists appear to be prejunctional, decreasing release of contractile neurotransmitters in the enteric nervous system.  相似文献   

10.
The objective of this study was to investigate the effects of sex steroids on spermiation in protandrous male black porgy, Acanthopagrus schlegeli. Experiments on common carp (Cyprinus carpio) were also conducted for comparison. Fifty male black porgy were divided into 5 groups and injected with a superactive analogue of mammalian luteinizing hormone releasing hormone (LHRH-A), 17,20,21-trihydroxy-4-pregnen-3-one (20-S), 17,20-dihydroxy-4-pregnen-3-one (17,20-DHP), 11-ketotestosterone (11-KT) or saline. The dosage of the sex steroids given on days 0, 2, 4 and 6 was 330, 330, 990 and 1980 µg kg-1 body weight, respectively. Milt volume and sperm concentrations were measured on days 0, 2, 4, 6, 8 and 10. Similar treatments were also conducted in 45 male common carp. Milt volume was significantly increased in black porgy after treatment with 20-S and 17,20-DHP; 17,20-DHP had stimulatory effects on spermiation at a lower dose (900 µg kg-1 body weight, p < 0.05) as compared to 20-S (1980 µg kg-1 body weight, p < 0.01). In the common carp, milt volume was also increased after treatment with LHRH-A and 17,20-DHP but not with 20-S. 17,20-DHP stimulated spermiation at a lower dose in common carp (330 µg kg-1 body weight) than in black porgy (990 µg kg-1 body weight). However, 11-KT did not stimulate spermiation in black porgy or common carp. The concentrations of plasma 11-KT could immediately reflect to the administration of exogenous 11-KT in black porgy.  相似文献   

11.
The -adrenergic response of teleost red blood cells (RBCs) enables the fish to maintain or even enhance the oxygen affinity of haemoglobin during various stress situations. The role of CAMP in the pronounced -adrenergic response of hypoxic rainbow trout RBCs was studied. Rainbow trout RBCs were incubated with three different -agonists (noradrenaline, adrenaline and isoproterenol, 10–9 - 10–4 M) at two oxygen tensions (PO 2, 155 and 8 mmHg), and thereafter cAMP accumulation and cellular water content were measured.The cAMP concentration of non-stimulated trout RBCs was ca. 1200 nmol/kg dw. Of the three -agonists used, isoproterenol was the most effective in formation of cAMP, followed by noradrenaline and adrenaline. Oxygen tension affected the accumulation of cAMP in two ways. At physiological catecholamine levels (1–100 nM) there was either no difference between normoxic and hypoxic cells or a slight increase in the normoxic ones. At high catecholamine concentrations the accumulation of cAMP was greater in the hypoxic than in the normoxic cells. Oxygen tension also affected the magnitude of cell swelling but had no effect on the catecholamine concentrations causing half-maximal swelling (EC50-values). The results indicate that, at physiological catecholamine levels, the -adrenergic response of rainbow trout RBCs is mainly regulated on the level of the Na+/H+ exchange.  相似文献   

12.
Immature brook trout (Salvelinus fontinalis) were randomly divided into a pH control, a pH and food control and an acid-stressed group. Fish in the first two groups were held at neutral pH and those in the last group were maintained at pH 4.2 for up to two months. The food supply to the pH and food control group was restricted to simulate the reduction in food intake demonstrated for acid-stressed trout. Plasma insulin levels were significantly decreased from 5–20 ng/ml to 1–2 ng/ml and plasma cortisol levels were significantly increased from 5–10 ng/ml to as high as 70 ng/ml in the acid-stressed brook trout. Concomitantly, a significant decrease of 21–39% in the proportion (volume density) of insulin immunoreactive -cells was observed within the principal pancreatic islets. Somatic growth was stunted and ultrastructural morphometry revealed the suppression of somatotrope secretory activity in the acid-stressed fish. Restriction of food supply induced a smaller but still significant decrease in circulating levels of insulin which was however not accompanied by a reduction in insulin immunoreactive -cells. The rise in plasma cortisol levels was not significant, and the plasma levels of glucose and protein were unaffected. Nevertheless, somatotrope secretory activity was suppressed and somatic growth was stunted. This study demonstrates for the first time the complexity of the endocrine response to acid stress and that some of the response to acid stress can be attributed to the lowering of food intake.  相似文献   

13.
Maturing male and female Atlantic salmon (Salmo salar L.) were held under three temperature regimes for 10 weeks between September and December: warm (constant 14–16 °C), ambient (decreasing from 11 to 5 °C), and cold (decreasing from 7 to 3 °C). Blood samples were analyzed for plasma steroid levels, and the fish were inspected for the presence of expressible milt (total volume and spermatocrit) and ovulation weekly. Samples of eggs were dry-fertilized with milt stripped from three males held at the same temperatures and incubated until the eyed stage. In females, levels of plasma testosterone (T) and 17β-oestradiol (E2) dropped as ovulation approached, concurrent with a rapid increase in levels of plasma 17α,20β-dihydroxy-4-pregnen-3-one (17,20β-P). In males, levels of T and 11-ketotestosterone (11-KT) peaked 2–3 weeks after the first appearance of expressible milt, while levels of 17,20β-P increased steadily and did not exhibit a definite peak. Exposure of females to cold water amplified and advanced the profiles of all three steroids compared with the ambient group, and increased the survival rates to the eyed egg stage. Cold water had no immediate effect on the male steroid profiles, but later, higher levels of 17,20β-P were evident compared with both the ambient controls and the warm water group, while the effects on 11-KT and T were more variable. Exposure to warm water completely inhibited both milt production and ovulation. Moreover, warm water modulated the steroid profiles of the males with lower 11-KT levels compared with ambient controls and lower 17,20β-P level compared with cold-water-treated males. In females, warm water resulted in total inhibition of the peri-ovulatory peak in 17,20β-P and prevented the normal decline of T and E2 levels associated with ovulation. The findings of the present study are highly relevant for broodstock management in aquaculture, as well in understanding the impact of climate change/temperature variability on wild salmon spawning.  相似文献   

14.
Changes in 17-estradiol (E2), estrone (E1), testosterone (T), 11-ketotestosterone (11KT), and 17,20-dihydroxy-4-pregnen-3-one (17,20-P) levels were correlated to changes in gonadosomatic index (GSI), vitellogenin concentration (Vg), ovarian and testicular histology during the annual reproductive cycle of the red porgy, Pagrus pagrus. The production of E2, E1, T and 17,20-P was confirmed by analysis of the steroidogenic activity of ovaries. In females, the average concentration of E2 was lower than 2 ng ml–1. E2 values first increased significantly at the stage of endogenous vitellogenesis and remained high during exogenous vitellogenesis. E1 levels were lower values than E2 (less than 300 pg ml–1), but they increased at the beginning of exogenous vitellogenesis. Estrogens concentrations followed similar pattern to Vg and were significantly correlated. Mean levels of T were mostly lower than 1 ng ml–1. They followed a pattern similar to that of E2 except for a further increase observed at the stage of final maturation. T and E2 levels were significantly correlated. The concentration of 11KT did not change significantly. The levels of 17,20-P ranged between 0.22 and 1.22 ng ml–1 but changes were not related to gametogenesis. In males, the concentrations of T and 11KT fluctuated significantly during the sexual maturity stages, showing a similar pattern and were significantly correlated to GSI changes. T levels increased during spermiogenesis and spermiation stages to reach about 3 ng ml–1. 11KT levels stayed about half those of T. The levels of estrogens showed no significant changes. Level of 17,20-P showed no significant variation related to male maturity. Results are discussed in relation to changes in plasma steroid levels during gametogenesis of other multiple spawner species.  相似文献   

15.
Diel cyclic hypoxia occurs with varying frequency and duration in freshwater habitats, yet little is known about its effects on reproduction of freshwater fishes. The present study shows that long-term exposure of goldfish (Carassius auratus) to cyclic hypoxia (0.8 ± 0.2 mg/l dissolved oxygen) for 9 h or more, per day, altered plasma lipid and sex steroid profiles, which in turn directly or indirectly suppressed ovarian growth and viable spermatozoa production. Hypoxia decreased total cholesterol and high density lipoprotein (HDL p < 0.05) and elevated triglycerides (TG; p < 0.05) in both sexes. Plasma steroid concentrations particularly of 17α-hydroxyprogesterone (17-HP), estradiol (E2), testosterone (T) in females, and T and 11-ketotestosterone (11-KT) in males were attenuated under diel hypoxic conditions. Intriguingly, both diel and continuous hypoxia elevated plasma E2 and vitellogenin levels in males. However, neither lipid nor steroid profiles recorded any variation in a dose-dependent manner in response to diel hypoxia. The reduced GSI, decreased number of tertiary oocytes, and motile spermatozoa in hypoxic fish clearly indicate suppression of gametogenesis. Thereby, prolonged diel cyclic hypoxia may affect valuable fishery resources and fish population structure by impairing reproductive performances and inducing estrogenic effects in males.  相似文献   

16.
Evidence has recently been presented for variation in the inducibility of various 7-alkoxycoumarin-O-dealkylase activities in liver microsomes from a number of mammalian species by -naphthoflavone (NF). In the present study we have investigated the inducibility of hepatic microsomal 7-methoxycoumarin-O-demethylase, 7-ethoxycoumarin-O-deethylase, 7-propoxycoumarin-O-depropylase and 7-butoxycoumarin-O-debutylase activities in rainbow trout by NF. O-demethylase activity was increased approximately 17-fold, O-deethylase and O-depropylase activities approximately 9-fold and O-debutylase activity approximately 25-fold. The kinetics of the various hepatic microsomal 7-alkoxycoumarin-O-dealkylase activities were investigated in control and NF-treated rainbow trout. The O-demethylase-, O-depropylase- and O-debutylase activities exhibited monophasic Michaelis-Menten kinetics in liver microsomes from both control and NF-treated rainbow trout, whereas the O-deethylase activity exhibited biphasic Michaelis-Menten kinetics in control liver microsomes and monophasic Michaelis-Menten kinetics in liver microsomes from NF-treated rainbow trout.  相似文献   

17.
ABSTRACT: The filamentous fungi Rhizopus , like many fungal species, possesses physiologically active substances. Rhizopus extract (RU) is reported to be effective for various aspects of growth and reproduction in many vertebrates. The effects of RU administration on body growth and plasma levels of steroid hormones were investigated in lacustrine sockeye salmon Oncorhynchus nerka . One-year-old fish were fed daily with RU (20 mg/kg feed) from July 1999 to October 2000 for 15 months. Fish were sampled every month and plasma levels of testosterone (T), 11-ketotestosterone (11-KT), estradiol-17β (E2) and 17α,20β-dihydroxy-4-pregnen-3-one (DHP) were measured by time-resolved fluoroimmunoassay. Body growth of RU-fed fish of both sexes increased significantly in 1+ and 2+ October, and 2+ January–March and July. All RU-fed males and one female matured in 2+ October. RU-fed 1+ precociously mature males showed increased plasma levels of T, 11-KT and DHP in 1+ October. In 2+ males, RU significantly elevated plasma levels of T from May to June, 11-KT from June to July, and DHP in October. In sockeye salmon, administration of RU accelerated body growth of both sexes and sexual maturation in males, suggesting physiologically active substances present in RU enhance somatic growth and sexual maturation by sex-specific mechanisms.  相似文献   

18.
Triploid fish have under-developed gonads due to altered reproductive endocrinology. Triploids of Indian catfish (H. fossilis) showed significantly reduced plasma levels of gonadotropin (GtH-II), testosterone (T) and estradiol-17 (E2) than that of diploids throughout the year, except for the resting phase, irrespective of sex. Plasma levels of GtH-II were significantly different (p<0.001) between diploid and triploid fish during preparatory, prespawning and spawning phase. The plasma testosterone contents in triploids were significantly less (p<0.001) than that of diploids, except during the resting phase. Triploid females showed very low titres of estradiol-17 (<1 ng ml–1) throughout the annual reproductive cycle in contrast to highly fluctuating levels in diploid females. Thus, this study for the first time provides information on reduced levels of GtH-II and sex steroids in plasma of male triploid fish and additional information on species-specific alteration of sex hormones in female triploids.  相似文献   

19.
This study investigated the effects of human chorionic gonadotropin (hCG), 17-hydroxyprogesterone (17P) and testosterone (T) on the in vitro production of 17-estradiol (E2) by isolated ovarian follicles of the rainbow trout (Oncorhynchus mykiss). 17P at 100 ng ml-1, and hCG at 100 IU ml-1 stimulated E2 production relative to controls, whereas lower doses were ineffective. T was the most effective in stimulating E2 production, followed by 17P and hCG respectively. The timecourse of E2 production was investigated for both static culture, and incubations with media replacement, with follicles being exposed to hormone treatment for 30 min, 1 or 3 h, or constantly. E2 production was observed after 30 min, 3 and 3-6 h in response to T, 17P and hCG respectively. Under static culture, E2 levels reached maximal levels in 6 h. Longer incubations resulted in further metabolism of E2 to E2-glucuronide, which resulted in the blurring of treatment effects after 18 h. Incubations with media replacement resulted in higher E2 production than in static culture. The results indicate that a 6 h incubation period is sufficient to produce significant increases in E2 production in response to hCG, 17P and T, and that incubations longer than 12 h result in losses E2 from the incubation media. These findings have implications for the validity of using static cultures to examine the effects of hormone treatment on the activity of steroid converting enzymes in vitro.  相似文献   

20.
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