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1.
Studies have shown that in both in vitro and in vivo tests, β‐hydroxy‐β‐methylbutyrate (HMB) increases the nonspecific cellular and humoral immune response and protection against diseases in animals. The present study examines the influence of HMB on nonspecific humoral defense mechanisms and protection against furunculosis in pikeperch (Sander lucioperca). β‐hydroxy‐β‐methylbutyrate was fed in a pelleted ration of 50 mg kg?1 feed day?1 for 4 weeks. Blood was drawn from 12 HMB‐fed and control‐fed pikeperch. The lysozyme and ceruloplasmin activities in the plasma, total immunoglobulin (Ig) levels, and total serum protein were analysed prior to and then after 2 and 4 weeks of HMB ingestion. After 4 weeks of HMB ingestion, a challenge test was performed by injecting the fish with live pathogenic Aeromonas salmonicida bacteria. β‐hydroxy‐β‐methylbutyrate at a dose of 50 mg kg?1 feed resulted in a statistically significant (P<0.05) increase in the lysozyme activity of the plasma, total Ig, and serum protein levels. Additionally, reduced mortality (40%) after the in vivo challenge with pathogenic A. salmonicida suggested that HMB‐activated nonspecific protection against furunculosis in pikeperch.  相似文献   

2.
The present study examined the influence of leucine metabolite β‐hydroxy‐β‐methylbutyrate (HMB), a natural product HMB, on nonspecific cell‐mediated defence mechanisms and protection against enteric redmouth disease (ERM) in pikeperch (Sander lucioperca). β‐hydroxy‐β‐methylbutyrate was fed in a pelletted ration at 50 mg kg?1 of the feed for 8 weeks. The phagocytic ability and potential killing activity of blood and pronephric phagocytes were examined in HMB‐ and control‐fed fish before and after 8 weeks of feeding HMB. Simultaneously, the proliferative response of blood and pronephric lymphocytes stimulated by mitogens concanavaline A and lipopolisaccharide were examined in experimental and control groups. Following 8 weeks of HMB feeding, a challenge test was performed by injecting the fish with live pathogenic bacteria Yersinia ruckeri. β‐hydroxy‐β‐methylbutyrate applied in the diet for 8 weeks prompted a statistically significant (P<0.05) increase in phagocytic ability and potential killing activity of the blood and pronephric phagocytes and the proliferative response of blood and pronephric lymphocytes. The changes in these mechanisms correlated with protection against Y. ruckeri, the ERM pathogen. The results showed that feeding HMB increased the nonspecific cell‐mediated defence mechanisms and protection against ERM by reducing cumulative mortality (30%) following the challenge with pathogenic bacteria. Future studies will include determination of optimal doses and protocols of oral application of HMB to maximize the immunomodulatory effects and protection against viral diseases in intensive pikeperch culture.  相似文献   

3.
ABSTRACT: The red seabream Pagrus major is a useful experimental fish for studying the endocrine control of oogenesis in teleosts. This study investigated the steroidogenic pathway for estradiol-17β (E2) biosynthesis in the ovarian follicles of red seabream. Intact follicles were isolated during vitellogenesis and incubated in vitro with different radiolabeled steroid precursors. When 17-hydroxyprogesterone (17-P), dehydroepiandrosterone (DHEA), or androstenedione (AD) were used as precursors, both testosterone (T) and estrone (E1) were synthesized by follicles, leading to estradiol-17β (E2) production. Serum steroid levels measured by enzyme-linked immunosorbent assay showed that T, E1, and E2 were present in the circulation at levels ranging from 1 ng/mL to 2 ng/mL throughout the day during the spawning season. In vitro conversion of E1 into E2, however, was 15.8-fold greater than T conversion into E2, suggesting that E2 is synthesized mainly via E1 rather than T. The results showed that E2 was synthesized from pregnenolone via 17-hydroxypregnenolone, DHEA, AD, and E1. Thus, the study demonstrated the complete steroidogenic E2 synthesis pathway in the ovarian follicles of red seabream, and revealed that E1 is the major precursor of E2.  相似文献   

4.
SUMMARY: We attempt to assess the impact of different levels of dietary β-carotene on immune function in rainbow trout. Semi-purified diets containing 0, 40, 200, and 400 mg β-carotene/kg dry diet were fed for 12 weeks to fish with average weight of 45 g. In addition to the humoral and cellular immune parameters, growth and feed utilization were examined. There were no marked differences in growth and feed utilization showing that β-carotene was not particularly efficient in enhancing growth of rainbow trout. Of the immune parameters measured, total immunoglobulin was significantly highest for the 200 mg β-carotene fed group. Serum complement activity (alternate pathway) at 200 and 400 mg β-carotene supplementation was significantly higher than that of the unsupplemented group. An increasing trend in lysozyme activity was observed, however, the differences among the groups were not significant. Phagocytic activity was similar among diet groups except at the highest level of supplementation where it was the maximum. Oxygen radical production by peripheral blood leukocytes appeared to be lower at higher levels of carotenoid supplementation. Overall, dietary β-carotene clearly enhanced immune response parameters in rainbow trout such as serum complement activity and total plasma immunoglobulin but did not show a definite influence for the other factors examined in the present study.  相似文献   

5.
There is an increasing problem with bacterial disease associated with stress in farmed frogs. In general, little is known about the immune system in farmed tropical ranid species and, in particular, about its functional ability. As part of a study on the non-specific immune system, immunostimulation by β-glucan was evaluated in preventing bacterial disease in cultured ranid frogs. Fifty frogs were grown to a mean weight of 40 g and separated into three experimental groups. These were exposed to a motile aeromonad bacterial challenge alone (Au), bacterial challenge with β-glucan (Au + glucan) or saline only (controls) to serve as controls. There were four replicate tanks containing five frogs per tank in each experimental group. After bacterial challenge, all the animals were observed twice daily, and the number of mortalities per tank was recorded. The liver was sampled in order to recover bacteria, and any colonies grown were identified. The survival of the β-glucan-treated frogs was significantly higher than that of the bacterial challenge group alone.  相似文献   

6.
The effects of intracerebroventricular (ICV) and intraperitoneal (IP) administration of galanin and β-endorphin on food intake have been studied in satiated tench held at 21 ± 2 °C. Food intake was evaluated at 0–2 h and 2–8 h after injection. The same treatments were carried out in tench and goldfish acclimated to 10 ± 1 °C. Central administration of either galanin or β-endorphin significantly increased food intake at 2 h and 8 h after injection in tench acclimated to 21 ± 2 °C, but no change in feeding was observed after IP treatments. Low temperature (10 °C) significantly reduced food intake in both tench and goldfish, and neither central nor peripheral administration of galanin or β-endorphin was found to modify feeding. The results indicate that galanin and opioids play a role in the central regulation of feeding in tench, but the stimulatory effect of these neuropeptides did not reverse the feeding inhibition produced by exposure to low temperature.  相似文献   

7.
In order to investigate the capacities of different tissues to oxidize fatty acids, total β-oxidation (mitochondrial and peroxisomal) of [1–14C]palmitoyl-CoA was determined in liver and red- and white muscle from adult and juvenile Atlantic salmon Salmo salar. By including potassium cyanide (KCN) in the assay medium, it was possible to differentiate between mitochondrial and peroxisomal β-oxidation capacities. Mitochondrial β-oxidation dominated in all tissues except in livers from juvenile fish where the peroxisomal β-oxidation dominated. In general, the red muscle possesses the highest fatty acid oxidation capacity, however, by taking into consideration the fact that white muscle occupies approximately 60% of the total body weight, this study demonstrates that the white muscle is an important tissue in the overall fatty acid catabolism.  相似文献   

8.
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9.
Oral administration of 11 β-hydroxyandrostenedione was used to sex inverse juvenile Stizostedion lucioperca (L.) reared under intensive culture conditions. Androgen was mixed into the commercial trout food in the following doses: 0, 30, 60 and 90 mg kg?1 diet. Administration (for 21 days) of 60 mg 11 β-hydroxyandrostenedione kg?1 of the diet produced 93% males and 7% bisexual fish. In hormone-treated groups, no morphological changes were observed in the liver. No significant differences were observed in growth or in the hepatosomatic index between the androgen-treated groups and the control group.  相似文献   

10.
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11.
ABSTRACT:   β-galactosidase of the intestine of Tilapia nilotica was purified by ammonium sulfate precipitation, followed by PAPTG-Sepharose 4B affinity chromatography, ethylenediamineetetraacetic acid ion-exchange chromatography, polyexchanger PBE 94 chromatofocusing, and Sephadex G-100 gel filtration. β-galactosidase was found to be a single band when examined by poly-acrylamide gel electrophoresis. The purifications of β-galactosidase were 27-fold from the crude extract. β-galactosidase showed optimum activity at pH 5.0 at 40°C, and was specifically found to be able to hydrolyze p -nitrophenyl β-galactopyranoside. It degrades galactan and agarose, and produces galactose. β-galactosidase was strongly inhibited by Hg2+ and PCMB. β-galactosidase is considered to be secreted by the upper and middle parts of the intestine and most of the activity was detected in the intestinal juice.  相似文献   

12.
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13.
Abstract.— The present study was conducted to investigate the effects of dietary supplementation of β‐1,3 glucan and a laboratory developed feed stimulant, BAISM, as feed additives for juvenile olive flounder, Paralichthys olivaceus. Eight experimental diets were formulated to be isonitrogenous and isocaloric and to contain 50.0% crude protein and 16.4 kJ of available energy/g with or without dietary β‐1,3 glucan and BAISM supplementation. β‐1,3 glucan (G) and BAISM (B) were provided at 0% in the control diet (G0B0) and at 0.05% G + 0.45% B (G0.05B0.45), 0.05% G + 0.95% B (G0.05B0.95), 0.1% G + 0.90% B (G0.1B0.9), 0.10% G + 1.90% B (G0.1B1.9), 0.15% G + 1.35% B (G0.15B1.35), 0.15% G + 2.85% B (G0.15B2.85), and 0.30% G + 2.70% B (G0.3B2.7) in experimental diets. After the feeding trial, fish fed G0.1B0.9, G0.1B1.9, and G0.15B1.35 diets had higher percent weight gain (WG), feed efficiency ratio (FER), specific growth rate (SGR), protein efficiency ratio (PER), and condition factor (CF) than those fed G0B0, G0.05B0.45, G0.05B0.95, G0.15B2.85, and G0.3B2.7 diets (P < 0.05); however, there was no significant differences among fish fed G0.1B0.9, G0.1B1.9, and G0.15B1.35 diets. Fish fed G0.1B0.9 and G0.1B1.9 diets had higher chemiluminescent responses (CL) than those fed the other diets (P < 0.05). Lysozyme activity of fish fed G0.1B0.9 diet was significantly higher than that of fish fed the other diets (P < 0.05). These results indicated that the optimum dietary supplementation level of β‐1,3 glucan and BAISM could be approximately 0.10% β‐1,3 glucan + 0.90% BAISM (G0.1B0.9) of diet based on WG, FER, SGR, PER, CF, CL, and lysozyme activity in juvenile olive flounder, P. olivaceus.  相似文献   

14.
Under aquaculture conditions, European eels (Anguilla anguilla) produce a high percentage of males (80–95%) that normally stop growing at 100–200 g. Females continue to grow to 500–750 g and obtain higher market value. Therefore, increasing the percentage of females in a population would be beneficial to the culture of eels. The present study was carried out in order to examine the effect of oestradiol and phytooestrogens on sex differentiation and growth rate of eels. Juvenile European eels with undifferentiated gonads were fed pellets containing oestradiol‐17β (E2) or phytooestrogens for 100–150 days. Feeding E2 resulted in 50–61% increase in body weight compared with the control. Oestradiol‐17β and phytooestrogens both elevated significantly the percentage of females in the population. Feeding E2 at 20 mg kg?1 feed resulted in 70% females, while lower concentration of E2 (2 mg kg?1) resulted in only 30% after 100 days (Experiment 1). The same dose given for 150 days (Experiment 2) resulted in 88% females, indicating that both, the concentration and duration of E2 treatments had a significant effect on sex differentiation. Fish fed genistein at 2 mg kg?1 for 100 days, resulted in 55% of females, but at a higher dose of 20 mg kg?1 there were only 15% females. These results demonstrate that phytooestrogens can be used as alternatives to gonadal steroids for sex manipulation in eels, but the optimal concentrations and duration are still to be determined.  相似文献   

15.
The effects of giving oral estradiol-17β (E2) and 17α-methyltestosterone (MT) on gonadal sex differentiation in the F2 hybrid sturgeon, the bester ( Huso huso female ×  Acipenser ruthenus male), are investigated. Giving E2 at 10 μg/g diet to fish from 14 months until 31 months of age induced incomplete feminization and resulted in approximately 40% abnormal ovary development in which oocytes were observed without ovarian lamellar structures and gonadal shape was similar to normal testis. Giving MT at 25 μg/g diet for the same duration failed to induce masculinization, and resulted in approximately 30% undeveloped gonads even at 30–37 months of age. In contrast, E2 and MT at only 1 μg/g diet given from 3 to 18 months of age was sufficient to induce feminization and masculinization, respectively. In these fish, feminization and masculinization were observed at 9 months, when most putative ovaries and testes were histologically distinguishable by the shape of the gonadal surface. These results indicate that sex reversal can be induced in these fish by hormone treatment that is started at 3 months age, before morphological differentiation occurs on the stroma of the gonads.  相似文献   

16.
ABSTRACT:   Estrogen receptor (ER) cDNA was cloned from the liver of common Japanese conger Conger myriaster . Common Japanese conger ER cDNA contains 2543 nucleotides including an open reading frame that encodes 596 amino acids, with a molecular weight of 66.1 kDa. The deduced amino-acid sequence of the common Japanese conger ER shares 85% identity with that of eel Anguilla japonica ER-β, and 39–46% and 53–59% identity with the deduced sequences of ER-α and ER-β of other species, respectively. In a phylogenetic analysis, the common Japanese conger ER was found to cluster with the ER-β of other species. The common Japanese conger ER-β also has six domains (A–F), which are conserved in the nuclear receptor superfamily. The amino-acid sequences in the C and E domains were highly conserved between common Japanese conger ER-β and other ER. However, the other domains showed low homology. In the female common Japanese conger, ER-β mRNA was highly expressed in the liver and pituitary gland. The expression levels of the ER-β gene increased from the oil droplet stage to the primary yolk globule stage and were maintained until the migratory nucleus stage.  相似文献   

17.
ABSTRACT:   Three diets supplemented with taurine, β-alanine andGABA and a control diet were fed to juvenile and fingerling Japaneseflounder to investigate the effects of the diets on growth and metabolicchanges of free amino acids in whole body and tissues. In experimentI, three diets supplemented with 1% each of taurine, β-alanineand GABA and a control diet were fed to juvenile Japanese flounderwith an initial mean body weight of 0.4 g for 4 weeks at20°C. In experiment II, the taurine-supplemented diet anda control diet were fed to fingerling Japanese flounder with an initialmean body weight of 15 g for 4 weeks at 20°C.Only supplementation of taurine in the diet of juvenile flounderimproved their growth performance in experiment I, but fingerlinggrowth performance of experiment II was not significantly relatedto taurine supplementation in the experimental diet. These resultssuggest that there is a greater requirement for taurine for thegrowth of juvenile Japanese flounder than fingerling Japanese flounder.  相似文献   

18.
Ractopamine is a synthetic catecholamine analogue which is known to improve feed efficiency, reduce carcass fat and increase lean muscle growth in terrestrial livestock (e.g. sheep, pigs, cattle and chickens), and therefore, may be useful in aquaculture production if similar effects can be elicited in fish. In the present study, rainbow trout, Oncorhynchus mykiss (Walbaum), (mean initial weight of 196 g) were fed the β-agonist ractopamine at 0, 5, 10, 20 or 40 parts per million (p.p.m.) of the diet for 12 weeks in a complete, randomized experimental design. Growth and feed intake were monitored throughout the experiment. Carcasses were analysed for protein, fat, energy and ash prior to the initiation of the trial, and subsequently, every 4 weeks. The growth rate, expressed as thermal-unit growth coefficient (TGC) was higher (P ≤ 0.05) in the 10 p.p.m. groups during weeks 1-4 and when averaged over all treatment weeks. Feed efficiency was significantly higher (P ≤ 0.05) in fish fed 10 and 5 p.p.m. ractopamine compared with controls during weeks 1-4 and 4-8, respectively, and was significantly higher (P ≤ 0.05) in all treated groups when averaged over the 12-week treatment period. Compared with controls, carcass protein was elevated in fish fed 5 p.p.m. ractopamine for 4 weeks, and in those offered 10 and 20 p.p.m. for 8 weeks. Carcass fat was significantly lower (P ≤ 0.05) in fish fed 10 p.p.m. ractopamine for 8 weeks, although the 40 p.p.m. group exhibited elevated fat levels in comparison with control fish. The data suggest that rapidly growing rainbow trout demonstrate age-related growth and carcass compositional trends similar to those of mammals, in that feed efficiency and carcass protein decrease while carcass fat increases with age. Oral administration of ractopamine to rainbow trout only modestly altered growth performance, and the trends were not as dramatic nor as consistent as those observed in homeothermic vertebrates fed ractopamine. Out of the concentrations tested, feed incorporation of ractopamine at 10 p.p.m. elicited the most pronounced effect on growth performance.  相似文献   

19.
Mud loach, Misgurnus mizolepis (Günther), were sex reversed using the immersion technique. Fry were raised in water containing 50, 100 or 200 μg oestradiol-17β I?1 for 1, 2 or 3 weeks. Survival rates decreased as dose and duration of treatment increased: in most instances they were significantly (P < 0.05) lower than those of the controls. Growth rates were unaffected except for fish in the 200 μg I?1 treatments. The 200 μg T?1 treatments for 2 and 3 weeks produced monosex female populations. The 100 μg I?1 treatment for 3 weeks produced 99% females and 1% intersex individuals. Histologically, ovaries of sex-reversed fish were similar to those of normal females. Morphologically, however, they were different in that the ovaries of sex-reversed fish were not connected to the genital pore. The hormone treatments affected the size and morphology of the pectoral fins, which exhibit sexual dimorphism in mud loach.  相似文献   

20.
Monosex populations can be a valuable management tool in culture of larger size largemouth bass (>400 g). In this study, we investigated the effective mode and duration of oestrogen and androgen administrations to produce monosex largemouth bass populations. The experiment consisted of nine treatments. In oral administration groups, we fed 40-day-old fry either 200 mg of an oestradiol-17β (E2) kg−1 diet or 60 mg of a 17α-methyltestosterone (MT) kg−1 diet for 30, 45 or 60 days. In bath treatments, we immersed fry in a 1 mg MT L−1 solution for 5 h a day on three or six occasions. For control treatment, we fed fry an ethanol-treated diet for 45 days. The frequency of females in the control group was 53.1%. Oral administration of E2 at all durations resulted in slight increases in the frequency of females (59.8–70.5%). Both modes of androgen administration at all durations were ineffective in altering phenotypic sex. The experimental results of our study indicated that male differentiation passed the point of being completely and functionally influenced by exogenous oestrogens, while female differentiation had already taken place and was no longer responsive to exogenous androgens in 40-day-old (33.5 mm) largemouth bass fry.  相似文献   

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