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61.
Steroid profiles of cultured and captive red drum (Sciaenops ocellatus L.) were investigated to evaluate the potential use of circulating sex steroid levels as a tool for gender identification in this species. Cultured 18‐month‐old fish were maintained on a 120‐day shortened photothermal cycle to induce precocious maturation. Additionally, wild‐caught fish were maintained in captivity under simulated natural photothermal conditions from late spring to early fall. Circulating 11‐ketotestosterone (11‐KT) levels were significantly higher in males compared with females during the early stages of gonadal growth in both cultured and captive fish. Plasma testosterone (T) levels showed a similar trend; however, the differences were significant only when males were already producing sperm. 17β‐estradiol (E2) concentrations were low in males and females before gonadal recrudescence but increased significantly with the progression of vitellogenesis in females. These results show that a test using a minimum concentration of circulating 11‐KT could be developed to differentiate between sexes in the early stages of gonadal maturation in red drum. Moreover, plasma E2 concentrations could be used to identify vitellogenic females. The two steroids considered together could help avoid possible error in gender identification due to unusually high levels of certain steroids encountered in some individuals. 相似文献
62.
N. B. Martin D. F. Houlihan C. Talbot R. M. Palmer 《Fish physiology and biochemistry》1993,12(2):131-141
Body composition and fractional rates of protein synthesis (percentage of the protein mass synthesized per day) were determined
in female Atlantic salmon returning to the River Tay, Scotland in July and in October after a 95 day period without food,
during which time the animals became sexually mature. During the 95 day period of starvation/sexual maturation the ventricle
and red muscle remained as a constant proportion of fresh weight whereas the liver, gill and ovary increased and the stomach
and white muscle decreased. Fractional rates of protein synthesis increased markedly in the liver, stomach and ovary during
the period of starvation/sexual maturation. In the gill, ventricle and white muscle fractional protein synthesis rates increased
slightly or remained constant. From the estimated rates of protein loss or gain in the various tissues it is concluded that
there is considerable protein turnover and repartitioning of amino acids during the period of starvation and sexual maturation.
The absolute rate of protein synthesis rates in the ovary indicates that this tissue made the largest contribution to the
energy and amino acid demands of the fish, whilst most of the amino acids required for maturation of the ovary were derived
from white muscle, principally as the result of increased muscle protein degradation. 相似文献
63.
Ovarian steroidogenesis during final oocyte maturation (FOM) in the spotted seatrout (Cynoscion nebulosus) was investigated by incubating ovarian fragments with tritiated pregnenolone, followed by chromatographic separation of
the radioactive products. The major tritiated steroid produced during FOM comigrated with 17α,20β,21-trihydroxy-4-pregnen-3-one
(20β-dihydro-11-deoxycortisol, 20β-S) on HPLC and TLC. Only minor amounts of radioactive material coeluted with 17α,20β-dihydroxy-4-pregnen-3-one
(17α,20β-P), 11-deoxycorticosterone (DOC), estradiol-17β and testosterone standards in the HPLC system. Additional chromatography
by TLC confirmed the presence of radioactive estradiol-17β and testosterone but not 17α,20β-P and DOC.
All the ovarian steroids producedin vitro during FOM were assayed for their ability to induce germinal vesicle breakdown (GVBD) of spotted seatrout oocytes. Twenty
grams of ovarian tissue were incubated with human chorionic gonadotropin and exogenous pregnenolone. The steroidal products
were purified by HPLC and TLC. Most of the maturation-inducing activity was confined to steroidal material which comigrated
in these systems with 20β-S. This material was active at a concentration of 1 ng steroid/ml medium in the GVBD assay. Smaller
amounts of material which coeluted with 11-deoxycortisol, DOC, 17α,20β-P and several minor unidentified fractions induced
GVBD at concentrations of 10 ng steroid(s)/ml.
The structure-activity relationships of authentic steroids in inducing GVBD of spotted seatrout oocytes was investigated.
Hydroxylation at the 17α, 20β or 21 positions increased potency to induce GVBD. Steroids with multiple hydroxyl groups at
the 17α and 20β positions (17α, 20β-P) and at the 17α, 20β, and 21 positions (20β-S) had maximum biological activity in the
GVBD bioassay. The results suggest that 20β-S is a major maturation-inducing steroid in spotted seatrout. 相似文献
64.
Sea bass (Dicentrarchus labrax) larvae were fed microparticulated compound diet containing 0 (FP0), 0.10 (FP10) and 0.33% (FP33) of a polyamine, spermine, from day 20 to day 38. LP group was fed live prey. This group exhibited the highest growth and survival. The addition of spermine did not lead to growth enhancement. A 33% survival improvement was obtained in FP33 group compared to FP0 group. The spermine addition affected the activity of pancreatic enzymes, trypsin, chymotrypsin and amylase, during larvae development. This non specific effect suggested that the action of spermine would be mediated by hormones. In the intestine, the FP33 group exhibited from day 31 higher activities of brush border membrane enzymes (leucine aminopeptidase and alkaline phosphatase) and lower level in a cytosolic enzyme (leucine-alanine peptidase) compared to FP10 and FP0 group. The diet containing the highest spermine level induced an enzymatic profile similar to that obtained in LP group and characteristic of a mature enterocyte. The initiation of enterocyte maturation at a proper development stage was associated to the survival improvement observed in FP33 group. 相似文献
65.
Sílvio Peixoto Greg Coman Stuart Arnold Peter Crocos & Nigel Preston 《Aquaculture Research》2005,36(7):666-673
Oocyte maturation and gonadosomatic index (GSI) of eyestalk ablated Penaeus monodon females collected from the wild and from two first‐generation domesticated lines were assessed. Frequency and diameter of the different oocytes, and the intensity of oocyte atresia, were compared among groups through histological assessments of the sections of the middle ovarian lobe. Digitized images from ovary sections were used to record the frequency and diameter of different oocyte types. Spawning performance of the three groups were expressed in terms of the percentage of females that spawned at least once (productive females), time from eyestalk ablation to first spawning (latency period) and the number of spawnings per female stocked. Final ovarian maturation was attained in all groups, as indicated by the presence of mature oocytes with cortical rods (cortical oocytes), dark‐green ovarian colour and high GSI values (5.83–6.86%). However, domesticated groups presented significant larger immature oocyte types (previtellogenic and yolky oocytes) and smaller cortical oocytes compared with wild females, indicating a reduced vitellogenic activity during final oocyte maturation. Additionally, the frequency of atresia was comparatively higher for both domesticated groups, which could be related to their inferior spawning performance. The implications of these results on the reproductive potential and development of domesticated P. monodon are discussed. 相似文献
66.
Commercially farmed Atlantic halibut (Hippoglossus hippoglossus) were reared at the Aga Marin's facility located on Dønna (Norway) under ambient environmental conditions in duplicate 15 × 15 × 8 m netpens (May 2004 to May 2005). Twenty fish were sampled five times over a twelve month production period during which time the average body weight increased from 1.26 to 2.08 kg (n = 100 fish). Body mass, fork length (LF), and the number and size distributions of fast muscle fibres were determined in male and female fish. All males matured during the autumn whereas no maturation was observed in females. From the point of maturation females had superior growth performance to males and body mass and the total cross-sectional area of muscle were 1.4-fold (P < 0.05) and 1.3-fold higher (P < 0.01) respectively by May 2005. The total number of fast muscle fibres per trunk cross-section at 0.55 LF was 24.5% higher in females (7.58 × 105) than males (5.80 × 105) prior to sexual maturation. In females, muscle fibre recruitment slowed with short days and low water temperatures (< 6.5 °C), but had increased to 1.01 × 106 by May 2005 (P < 0.001). In contrast, there was no growth and no increase in muscle fibre number in males following the onset of maturation. The distribution of muscle fibre diameters prior to maturation in males was also significantly different between male and female fish matched for LF. The results illustrate a sexual dimorphism of muscle fibre recruitment patterns in Atlantic halibut and highlight the adverse affects of sexual maturation in males on muscle growth. 相似文献
67.
Three-spined stickleback Gasterosteus aculeatus, males were implanted with Silastic capsules filled with different aromatase
inhibitors; 1,4,6-androstatriene-3,17-dione or the non-steroidal CGS16949 A, 4-(5,6,7,8-tetrahydrimidazol [1,5-a]pyridin-5-yl)
benzonitrile monohydrochloride or empty capsules. The fish were then exposed to long or short photoperiod. Under the long
photoperiod most fish in all treatments displayed a hypertrophied kidney (a secondary sexual character in sticklebacks) and
completed, quiescent spermatogenesis, similar as in the natural spawning period. Under the short photoperiod the controls
had unstimulated kidneys and an active spermatogenesis, whereas the males implanted with both aromatase inhibitors had stimulated
kidneys, though not to the extent as in the long photoperiod, and completed, quiescent spermatogenesis. These findings suggest
that aromatization is of importance for the inhibitory effects of short photoperiod on reproduction in the stickleback.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
68.
B. Lal 《Fish physiology and biochemistry》2007,33(4):455-462
Numerous studies are available reporting the effects of pesticides on reproductive activity in Indian fishes. The majority
of these reports deals with histopathological changes in gonads and endocrine glands involved in the regulation of reproduction
following treatment with different pesticides. Pesticides are reported to cause degenerative changes in gonads and arrest
gametogenic processes either by acting directly on the gonads or by interfering with the secretory activity of the hypothalamo-hypophyseal-gonadal/thyroid
axis that regulates various reproductive events. Secretion of hormones such as gonadotropin-releasing hormone (GnRH), gonadotropin,
growth hormone, adrenocorticotropic hormone (ACTH), testosterone, estrogens, 17,20β-dihydroxyprogesterone and thyroid hormones
are in general lowered, leading to cessation of gametogenesis, vitellogenesis, oocyte maturation, ovulation, spermiation,
etc. Adverse effects of pesticides have also been demonstrated on fecundity, fertilization, hatching, and postembryonic development.
The effects are highly variable and depend on the nature, dose, and mode of application of the pesticides. 相似文献
69.
Predicting the suitability and reliability of traits associated with juvenile growth as indirect selection criteria for choosing future broodstock requires accurate and repeatable estimates of genetic (co)variation for growth traits at different ages. We compared juvenile wet weight of black bream Acanthopagrus butcheri (Munro) at 6 months of age with wet weight, dressed weight, fillet yield and gonad weight in tagged individuals at 18 months of age, following 12 months of farm grow‐out. Fish survival and tag retention was high, and there was significant among‐family variation for all traits. The phenotypic correlations among wet weight, dressed weight and fillet yield at 18 months of age were very high (0.93–0.97) and similar to their genetic correlations (0.96). Importantly, the phenotypic correlations between wet weight at 6 months and wet weight, dressed weight and fillet yield at 18 months were high (0.63–0.65), and so too were their genetic correlations (0.66–0.73), indicating the potential for using wet weight in the hatchery as a selection criterion for improved weight and meat yield of fish at harvest. Gonad weight shared little or no phenotypic or genetic correlation with these other traits, suggesting that selection for faster growing fish will not affect fecundity or sexual maturation rate. It appears, however, that cultured black bream do become sexually mature more rapidly than wild fish, as 78% of all fish harvested in this study had developing or mature gonads, whereas less than 50% of fish in wild populations are reproductively mature by the same age. Precocious sexual development may lead to uncontrolled spawning in grow‐out ponds and a potential loss of selection gains. 相似文献
70.
Antnio Fernando Gervsio Leonardo Elizabeth Romagosa Maria Inês Borella Sergio Ricardo Batlouni 《Aquaculture (Amsterdam, Netherlands)》2004,240(1-4):451-461
In the months of January 2001 and 2002, female cachara Pseudoplatystoma fasciatum were selected during their first and second gonadal maturation (2 years and 7 months old and 3 years and 7 months old, respectively) with an of oocyte diameter of 937.5 μm (82.5% with central nuclei and 17.5% with peripheral nuclei). Nine females in first maturation received two doses of carp pituitary extract (CPE), 0.5 mg/kg and 5.0 mg/kg; seven received two doses of human chorionic gonadotropin (hCG), 5 and 10 IU/g; five received doses of 0.5 CPE mg/kg and 5 hCG IU/g (CPE+hCG); and four received 0.9% saline (saline). Nine females from CPE and seven from hCG presented oocytes with the same diameter at the moment of oocyte release (100% with germinal vesicle breakdown and fertilization rate of 53.44±18.3 and 54.81±11.8%; larvae number of 165,330±94.1 and 158,570±20.6, respectively). The five females from CPE+hCG did not respond to the hormonal treatment. The four females from the saline group did not ovulate. In January 2002, 6 of 15 selected females that were going through the second reproductive cycle received CPE (five received hCG and four received saline), showing oocyte diameters similar to the ones in the first maturation. At stripping, CPE females had an oocyte diameter of 1062.5 μm (the hCG females had oocyte diameters ranging from 937.5 to 1125.0 μm; fertilization rates of 56.08±30.9 and 81.90±17.3%; 364,547±244 and 633,129±190, larvae, respectively). The fertilization rates and larvae number were higher in the second gonad maturation, both for CPE and hCG. 相似文献