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1.
Gene transfer has offered a new tool for the development of improved fish strains for aquaculture. Monosex fish populations could minimize the impact of genetically modified organisms in the environment. In Oreochromis aureus, the use of pseudofemale spawners (sex-reversed male with a female phenotype) is an alternative technique for producing genetically male tilapia offspring. O. aureus fry were treated with 17β-estradiol at 100 mg/kg of food for 45 days. We obtained 77.1% females and 45.9% in the control group. Females randomly taken from the treated group were crossed with normal males. Fry from pseudofemales producing more than 90% male progenies were submitted to 17 β-estradiol treatment to obtain F2 pseudofemales. The results of the sex-reversal were low and variable ranging between 66.0 and 84.3% females. F2 pseudofemales were crossed with transgenic males from the F70 line (O. aureus × O. urolepis hornorum) and non-transgenic (O. aureus) males. The sex ratio of progeny of F2 pseudofemale deviated significantly (P < 0.01) in favor of males in the crosses with transgenic (90.2%) and non-transgenic (89.3%) males compared to the results observed with normal females (51.0 and 52.3%, respectively). The mean fry production with pseudofemales (per m2/day) was similar to the normal females in the crosses with transgenic and non-transgenic males. To our knowledge this is the first report on the production of a near monosex population in genetically modified fish.  相似文献   

2.
To examine the age, growth and reproduction of silky sharks, Carcharhinus falciformis, in the waters off northeastern Taiwan, 469 specimens (213 females and 256 males) were collected from August 2000 to January 2002 at the Nanfanao fish market, northeastern Taiwan. The relationship between body weight (W) and total length (TL) for both sexes combined was expressed as: W = 2.92 × 10−6 TL3.15 (n = 469, p < 0.01). The relationship between TL and vertebral centrum radius (R) for both sexes combined data was estimated as: TL = 25.979 + 18.197R (n = 250, p < 0.01). Growth bands (including translucent and opaque zones) in precaudal vertebrae formed once a year between December and January and were counted up to 11 and 14 for females and males, respectively. The von Bertalanffy growth function (VBGF) was used to model the observed length at age data. The sexes combined VBGF predicted an asymptotic length (L∞) = 332.0 cm TL, growth coefficient (k) = 0.0838 year−1, age at zero length (t0) = −2.761 year (n = 250, p < 0.01). Size at 50% maturity for males was estimated to be 212.5 cm based on the logistic curve, which corresponded to 9.3 years. Females matured at 210–220 cm, which correspond to 9.2–10.2 years. The length at birth was estimated to be 63.5–75.5 cm TL. The number of embryos per litter was 8–10 and sex ratio of embryos was 1:1.  相似文献   

3.
A selection of 16 field isolates of Photobacterium damselae from marine rainbow trout farms in Denmark was subjected to phenotypic and genotypic characterization and pathogenicity to fish. All isolates belonged to the subspecies damselae , being positive for haemolysis, motility and urease. There were considerable differences in haemolytic properties, some isolates presenting a broad zone of haemolysis and others only a narrow zone. Pulsed-field gel electrophoresis revealed a high diversity indicating that P. damselae subsp. damselae is an opportunistic, not clonal pathogen in Danish marine rainbow trout. Virulence of the strains to rainbow trout was highly variable with LD50 values ranging from 3.9 × 103 to 1.5 × 108 cfu at 20 °C. The virulence was significantly higher at 20 °C than at 13 °C. The strains with the strongest haemolytic properties were the most virulent suggesting a strong involvement of haemolysin in the pathogenesis. The pathological changes were consistent with a bacterial septicaemia and the haemorrhages were more pronounced than for most other bacterial infections.  相似文献   

4.
Reference (physiological) value intervals determined by the lower 2.5% and upper 97.5% quantiles were calculated for total calcium (Ca t ) and inorganic phosphate (P) in farmed rainbow trout, Oncorhynchus mykiss , at an age of 10–12 months in raceway culture. Total calcium levels were significantly ( P ≤0.0009) greater in males (2.63–4 mmol L−1, n =47, mean weight 359±142 g) than in immature females (2.48–3.97 mmol L−1, n =410, mean weight 400±145 g). The reference range for P in immature females and males was 3.09–9.32 mmol L−1 ( n =467, mean weight 401±144 g). The distribution and density of the quantiles in the tested reference group were made possible by the use of histograms, which showed normal distributions for Ca t in males but not for Ca t and P in immature females and males, in which a sinistral asymmetry was found.  相似文献   

5.
The honmoroko has been inferred to have an XX/XY sex determination system, but the parental genome can also affect the sex ratio of the offspring. The extent of parental effects on sex determination was examined by checking the sex ratios of F1 and F2 gynogenetic diploids and control diploids. Eleven gynogenetic broods from different females consisted of all or nearly all females, but eight broods showed a variable proportion of males (<50 %). One second-generation brood of gynogenetic diploids consisted wholly of females, but others produced some males. In crosses with a control diploid female, four males from a high-percentage male brood of gynogenetic diploids produced offspring with a balanced sex ratio. Sib-mating between a gynogenetic female and three gynogenetic males from the brood produced predominantly male progeny. These results suggest that there are at least four possible genotypes: genotypic female (XX), phenotypic female carrying a silent Y chromosome, genotypic male (XY), and genotypic supermale (YY). These inferences suggest that this fish has an XY system but a relatively high proportion of females possess a mutated, silent Y chromosome which does not lead to testis formation.  相似文献   

6.
A sample of the all-male population of rainbow trout resulting from the dietary administration of 17α-methyltestosterone at a concentration of 3 mg/kg of food to juvenile fish during the 90-day period following “swim up” was grown to sexual maturity. It was observed that in many specimens there were deformations of the reproductive system which prevented the normal expression of milt although spermatozoa from the testes were viable.Sperm specimens removed surgically or normally expressed from mature fish were separately used to fertilise the mixed ova from untreated females. All the progeny of one such pairing were females. This indicates that in the rainbow trout it is the female sex which is homogametic.Samples of the all-female population which resulted from the dietary administration of 17β-oestradiol at a concentration of 20 mg/kg of food to rainbow trout fry during the 56-day period following “swim up” were also grown to maturity. The ova stripped from these fish were separately fertilised with mixed milt expressed from normal males. The progeny of two of five such pairings had a combined male to female ratio of 2.2, indicating that in rainbow trout the male is heterogametic for sex. The results were insufficient to permit any reliable estimate of the degree of impairment of the viability of the YY constitution.A method of producing single sex populations by the mating of sex reversed with normal fish is discussed.  相似文献   

7.
Abstract. Results of a 16 year (1977–1992) study of hybrids obtained from crossing two cyprinid fish, crucian carp, Carassius auratus gibelio (Bloch) (bisexual form), and common carp, Cyprinus carpio L., are presented. The ability to produce diploid eggs in F1 females (resulting from chromosome endoreduplication in early oogenesis) was responsible for the high yield of spontaneous diploids in gynogenetic progenies of F1 females and for triploidy in hybrids from back-crosses of F1 females with males of the parent species. Different types of hybrids, including diploid and triploid gynogenetic, tetraploid (amphidiploid) and androgenetic progenies, were obtained. Diploid and some triploid hybrids (females only) were reproduced inter se by induced gynogenesis in several subsequent gynogenetic generations. Amphidiploid hybrids were obtained by crossing triploid F8 females with diploid common carp males or by crossing diploid gynogenetic females with diploid inverted hybrid males producing diploid sperm. Results of cytogenetic investigations and fish culture properties in hybrids are presented. The scientific and practical significance of the data obtained are discussed.  相似文献   

8.
Infectious hematopoietic necrosis virus (IHNV) is a major constraint to rainbow trout culture. Yellowstone cutthroat trout (Oncorhynchus clarki bouvieri) have greater resistance to this virus than do rainbow trout (O. mykiss), but the genetic mechanism of this resistance is not understood. We conducted a genome scan using a backcross of cutthroat trout into a rainbow trout background to estimate the number and locations of quantitative trait loci (QTL) associated with IHNV resistance and growth in trout. IHNV resistance was considered in terms of both survival (binary trait) and days to death (quantitative trait). The genetic map was scanned using interval mapping via two different approaches: one model considered survival alone and a second two-part model combined both survival and days to death. Three QTL were significantly (P ≤ 0.05) associated with virus resistance genome-wide, explaining 32.5% of the phenotypic variation. Cutthroat alleles at two of these QTL resulted in increased resistance to the pathogen, as expected. No growth QTL were detected in this cross. We suggest that these traits are genetically independent.  相似文献   

9.
Although brook trout and the Arctic char hybrids are able to reproduce, individuals with decreased fertility or even fish that are unable to produce any gametes have been also described. Abnormal gonadal development and disturbances in the gamete production in the char hybrid offspring may be triggered by the odd chromosome number and disturbances in their pairing during meiosis. To verify this hypothesis, cytogenetic examination and the gonadal histology analysis of the brook trout x Arctic char hybrids were carried out. Diploid chromosome number in the studied char (F1) hybrids varied from 82 to 84 (FN = 99–102). Among 28 hybrids, 12 males, three females, nine intersex individuals and two sterile specimens were described. In the case of two individuals, gonads were not found. Diploid chromosome numbers in the males and intersex individuals varied from 82 to 84. Chromosome numbers in the females were 82 and 83 chromosomes. Two sterile fish exhibited karyotypes composed of 82 and 84 chromosomes. Predominance of the ovarian component in the intersex gonads and gonadal sex ratio distortion towards the males suggested hybrid females had problems with gonadal differentiation. However, the lack of the clear relationship between chromosome number and gonadal development in the studied hybrids did not support our hypothesis that odd chromosome number may be responsible for such reproductive disturbances in the hybrid individuals. We have presumed that sterility and intersexual development of the gonads may be caused by interactions between brook trout and Arctic char genes on the sex chromosomes and autosomes rather than unpairing of the parental chromosomes.  相似文献   

10.
Oral administration of 17β-oestradiol at 20 mg/kg diet for a period from 0 to 60 days following “swim-up” resulted in the sex reversal of male brook trout and the production of essentially all-female populations. The gonads of these animals were indistinguishable from the ovaries of untreated fish.Oral administration of this hormone at the same concentration but for the period from 0 to 40 days resulted in a population which comprised 67% females, 21% males and 12% bisexual animals.Within the control group, the growth rate of males was significantly greater than that of females. Growth in the all-female stocks produced by dietary oestradiol administration (0–60 days) was significantly lower than that of the untreated population taken as a whole but was identical to that of the control females.The growth of brook trout during the first year was closely comparable to that of rainbow trout reared under identical conditions. During the second year, the growth of the rainbow trout exceeded that of the brook trout. At 19 months of age, all the animals in the control and oestradiol treated brook trout populations were fully mature; maturity in the rainbow trout was substantially confined to males.  相似文献   

11.
Two anaesthetics, clove oil and methane sulphonate (MS-222), were examined for their effects on the olfactory nerve response of masu salmon ( Oncorhynchus masou Brevoort) and rainbow trout ( O. mykiss Walbaum). Exposing both species to clove oil for 3 min at concentrations of 50 and 100 mg L−1, or for 10 min at 50 mg L−1, did not significantly reduce their olfactory response. Directly applying clove oil anaesthesia to the olfactory epithelium significantly reduced olfactory response though after 20 min, olfactory response recovered to 70% and 52% of pre-treatment levels in masu salmon and rainbow trout respectively. Compared with the post-anaesthetic recovery of responses after clove oil (50 mg L−1), buffered MS-222 (100 mg L−1) with NaHCO3 (100 mg L−1), and unbuffered MS-222 (100 mg L−1) treatment for 3 min, the response after MS-222 treatment declined gradually and significantly, but not after clove oil and MS-222+NaHCO3 treatments. Clove oil appears to be an effective and relatively safe anaesthetic for salmonids with little long-term impact on their olfactory response, which plays a crucial role in their life history.  相似文献   

12.
The effect of hydrogen peroxide (H2O2) treatment on the clearance of formalin-killed Flavobacterium branchiophilum from the gills of rainbow trout was examined. In untreated control fish, clearance was characterized by a rapid initial phase, with 50% reduction in bacterial antigen in the first 12 h after exposure. The bacteria then cleared more gradually, with total clearance being achieved by 40 h. Treatment of fish with 100 p.p.m. H2O2 did not influence bacterial clearance compared to untreated controls. Exposure for 1 h to H2O2 concentrations ≤ 100 p.p.m. caused no detectable clinical signs or evidence of ultrastructural damage to the respiratory epithelium. However, levels in excess of this caused significant gill damage.  相似文献   

13.
For many aquaculture finfish species, the current broodstock have been collected from the wild or have undergone only a few generations of domestication. The Atlantic halibut (Hippoglossus hippoglossus) aquaculture industry in Atlantic Canada has retained F1 juveniles (n=145) from the 1996 spawning of wild adults for candidate broodstock. Through the development and use of a five-microsatellite DNA marker multiplex, we determined the parentage of these 1996 F1 individuals, which are being reared at one government and two industry hatcheries, and evaluated the change in genetic variation between the wild and the 1996 F1 stock. In the three groups of F1 fish, single parental pairs were assigned to 98%, 96% and 100% of individuals. Large full- and half-sibling groups were identified within and across F1 groups and, overall, only 36% of attempted crosses were represented in the retained fish. Effective population size in the parental group decreased from 27 to 13 when variance in family size was accounted for and to 12.5 when changes in gene diversity (compared to the combined F1 stocks) were considered. Statistically significant differences in measures of genetic variation were not widely observed between groups (original wild sample, parental group, three F1 groups and combined F1). However, the F1 population shows a 26% decrease in total allele numbers compared to the wild sample. These observations demonstrate the utility of genetic tools in the evaluation of genetic diversity and determination of pedigree during the establishment of new broodstock. They also emphasize the necessity for closely monitoring future matings among these fish and suggest the need to introduce additional genetic variation into this group of Atlantic halibut broodstock.  相似文献   

14.
An in vitro method was developed to assess the digestibility of phosphorus in 12 plant and animal feed ingredients for rainbow trout Oncorhynchus mykiss (Walbaum). The method simulates the gastrointestinal tract of the rainbow trout with regard to pH and gastrointestinal enzymes. Phosphorus solubility was measured after acid digestion (pH 3) with and without gastric enzymes, after alkaline digestion (pH 9) with and without intestinal enzymes, and after a two-step process involving acid and alkaline digestion. Commercially available digestive enzymes from mammals were compared with digestive enzymes from rainbow trout. Correlating in vitro digestibility with in vivo digestibility showed that acid digestion with both commercial enzymes ( r 2=0.98, P  < 0.05) and trout enzymes ( r 2=0.94, P  < 0.05) predicted the in vivo digestibility of animal feed ingredients. Alkaline digestion with both enzyme systems (commercial r 2=0.79; trout r 2=0.74, P  < 0.05) or without ( r 2=0.82, P  < 0.05) enzymes predicted the in vivo digestibility of ingredients from animal byproducts but not those from plant products. The in vitro digestibility with two enzyme steps (acid and alkaline) predicted in vivo digestibility of plant and animal ingredients ( r 2=0.79 for commercial enzymes and r 2=0.74 for trout enzymes) better than did one-step acid or alkaline digestion.  相似文献   

15.
Abstract The possible mechanism of inactivation of the toxicity of Aeromonas salmonicida extracellular products (ECP) by normal rainbow trout serum was investigated using juvenile rainbow trout. ECP was prepared from culture supernatant by an acetone precipitation method. The ECP was incubated with normal rainbow trout serum at 20°C for 2 h, and the interrelationship between ECP proteolytic activity and immune complex-initiating, haemolytic complement activity (CH50) of normal serum against antibody-sensitized goldfish red blood cells was evaluated. When normal serum was incubated with increasing concentrations of ECP, the CH50 activity of serum decreased. The CH50 activity was completely abolished in serum treated with undiluted ECP. ECP treated with serum was administered to trout intraperitoneally to determine mortality. All the fish receiving untreated ECP (0.05 ml = 0.5 mg protein) alone died within 24 h. When ECP was treated with serum at 1:1 to 4:1 (serum: ECP) in volume a similar high mortality was produced. These inocula possessed high protease activity and no or low CH50 activity. However, mortality decreased and finally no mortality was recorded as ECP was treated with large volumes of serum (9:1 to 19:1). These inocula had lower protease activity and considerably higher CH50 activity. Fish receiving ECP treated with heat-inactivated serum at 19:1 showed 100% mortality. A serum: ECP inoculum derived from fish which had been administered lipopolysaccharide from Salmonella enteritidis and which possessed a low CH50 activity also gave a high mortality when used at 19:1. These results suggest that rainbow trout complement is implicated in the inactivation of toxicity of A. salmonicida ECP.  相似文献   

16.
Abstract. Alpha foetoprotein (AFP)-like immunoreactivity was detected by double immunodiffusion in thesera of adult rainbow trout, Oncorhyachus mykiss (Walbaum) with histologically confirmed hepatocellular carcinoma experimentally induced in microinjection of embryos with aflatoxin B1 (AFB1). Partial characterization indicated that this AFP-like immunoreactivity gave immunologic cross-reaction of partial identity with human AFP. had alpha1 electrophorctic mobility, and an estimated molecular weight of 72kDa. Elevated serum AFP-like immunoreactivity levels were also measured by RIA in seven out of eight adult rainbow trout with hepatocellular carcinoma, and in three out of 17 AFB1-exposed trout without demonstrable grosws or microscopic evidence for hepatocellular neoplasms. No serum AFP-like immunoreactivity was detected or measured in normal healthy age matched DMSO-control rainbow trout. These data are consistent with the following conelusions: (1) AFP-like immunoreactivity detected and measured in the sera of rainbow trout with hepaloecllular careinoma is an analogue to human AFP; and (2) the elevated serum AFP levels measured in adult rainbow trout wilh hepatocellular careinoma resrmble those found in humans with this same malignancy. These data further suggest that serum AFP measurements might be useful to confirm the appearance of hepatocellular carcinoma in experimental fish carcinogen-assay systems, and to detect hepatocellular neoplasia in high-risk wild fish populations exposed to carcinogenie pollutants.  相似文献   

17.
The culture of the mulloway (Argyrosomus japonicus), like many other Sciaenidae fishes, is rapidly growing. However there is no information on their metabolic physiology. In this study, the effects of various hypoxia levels on the swimming performance and metabolic scope of juvenile mulloway (0.34 ± 0.01 kg, mean ± SE, n = 30) was investigated (water temperature = 22 °C). In normoxic conditions (dissolved oxygen = 6.85 mg l− 1), mulloway oxygen consumption rate (M·o2) increased exponentially with swimming speed to a maximum velocity (Ucrit) of 1.7 ± < 0.1 body lengths s− 1 (BL s− 1) (n = 6). Mulloway standard metabolic rate (SMR) was typical for non-tuna fishes (73 ± 8 mg kg− 1 h− 1) and they had a moderate scope for aerobic metabolism (5 times the SMR). Mulloway minimum gross cost of transport (GCOTmin, 0.14 ± 0.01 mg kg− 1 m− 1) and optimum swimming velocity (Uopt, 1.3 ± 0.2 BL s− 1) were comparable to many other body and caudal fin swimming fish species. Energy expenditure was minimum when swimming between 0.3 and 0.5 BL s− 1. The critical dissolved oxygen level was 1.80 mg l− 1 for mulloway swimming at 0.9 BL s− 1. This reveals that mulloway are well adapted to hypoxia, which is probably adaptive from their natural early life history within estuaries. In all levels of hypoxia (75% saturation = 5.23, 50% = 3.64, and 25% = 1 .86 mg l− 1), M·o2 increased linearly with swimming speed and active metabolic rate (AMR) was reduced (218 ± 17, 202 ± 14 and 175 ± 10 mg kg− 1 h− 1 for 75%, 50% and 25% saturation respectively). However, Ucrit was only reduced at 50% and 25% saturation (1.4 ± < 0.1 and 1.4 ± < 0.1 BL s− 1 respectively). This demonstrates that although the metabolic capacity of mulloway is reduced in mild hypoxia (75% saturation) they are able to compensate to maintain swimming performance. GCOTmin (0.09 ± 0.01 mg kg− 1 m− 1) and Uopt (0.8 ± 0.1 BL s− 1) were significantly reduced at 25% dissolved oxygen saturation. As mulloway metabolic scope was significantly reduced at all hypoxia levels, it suggests that even mild hypoxia may reduce growth productivity.  相似文献   

18.
Growth of newly metamorphosed Macrobrachium australiense was monitored in individually vidually held and group held laboratory animals over 28 weeks. A breeding population was also established in a farm dam and the growth of young juvenile F1 progeny was recorded for a similar time. Up to 26 moults were recorded in this period and intermoult periods increased with age. Prawns held in groups grew better than those held individually. Reproductive maturity was attained by some females in group held laboratory and farm dam animals within the observation period. Length—weight regression equations were calculated for laboratory maintained prawns, i.e., log W = 0.44+ 2.44 log L; log W = 0.45 + 2.46 log L for individually held males and females, respectively; log W = 0.27 + 2.70 log L for group held males and females.  相似文献   

19.
Abstract. Both fingerling and adult rainbow trout were given intraperitoneal inoculations of the 131P2 reovirus which did not result in mortalities but produced a subclinical disease in 56% of the adults and in 65% of the juvenile fish. Sera from virus infected adult trout contained virus neutralizing and precipitating antibodies and demonstrated immunofluorescence of antigen(s) specific for the 13P2 virus. Virus infection was characterized by increased virus titres and a multifocal reticulo-endothelial granulomatous hepatitis, occasionally accompanied by a fibrosing pancreatitis. Electron microscopy of infected liver tissues demonstrated arrays of 13P2 virus particles in a reticuloendothelial cell phagosome and in a hepatocyte lipid inclusion body from one of three juvenile fish examined. These results show that 13P2 virus inoculation of rainbow trout causes a non-virulent virus infection accompanied by specific humoral antibodies. These antibodies are sufficient in titre for use in future serologic studies of the virus. Further discussion regarding the pathogenesis of this virus in bluegills versus rainbow trout is presented.  相似文献   

20.
Nutritional strategies to reduce both phosphorus (P) and nitrogen (N) excretion relative to growth of rainbow trout were tested in a 2 × 3 factorial experiment. The two factors were `dietary P level' and `dietary lipid level.' Reduction in dietary P from 14 to 8 g kg–1 dry diet was achieved by partial substitution of dietary fish meal with a combination of full-fat soyabean meal, corn gluten and spray-dried blood meal. Triplicate tanks of 35 rainbow trout per tank were fed experimental diets for 16 weeks and grew from approximately 40 to 250 g, in 15 °C spring water. All tanks were fed the same percent biomass per day. Diets were isonitrogenous, and dietary energy varied with dietary lipid. Diet digestibility data and results of the experiment were used to construct N and P budgets for the fish fed the various diets. A reduction in dietary fish meal from 500 to 200 g kg–1 dry diet, corresponding to a reduction in dietary P from 14 to 8 g kg–1 dry diet, resulted in >50% reductions in both solid and dissolved P waste, but did not affect growth, feed efficiency ratio (FER) or sensory characteristics of rainbow trout. Increasing dietary lipid from 170 to 310 g kg–1 dry diet led to higher growth rate and FER, and lower total N waste relative to weight gain, but did not change protein retention. Increasing dietary lipid level increased deposition of lipid in whole bodies of rainbow trout, and resulted in discernible differences in sensory characteristics of trout fillets.  相似文献   

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