首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
Induction of triploidy in grass carp was accomplished by means of thermal shocks to eggs shortly after fertilization. Triploidy occurred most often with cold shocks at 5–7°C and at durations of 25–30 min starting 2.0–4.5 min after fertilization. Estimated percent triploid ranged from 50 to 100% on five occasions. With one exception, cold shocks of 5–7°C for less than 25 min did not induce triploidy, and cold shock durations of 30 min or longer generally resulted in 100% mortality. A heat shock of 40°C for 1 min, 4.75 min after activation, was the only heat treatment which produced triploidy (8%) with 81% surviving to the blastula stage. Fertilized eggs immersed in a solution of cytochalasin B (10 mg/l, 0.1% DMSO) for 10 min, 12 min after activation, resulted in 54% of the eggs surviving to the blastula stage with none found to be triploid.  相似文献   

2.
Abstract. This study was designed to investigate the potential of heat shock to produce triploidy in brown trout, Salmo trutta L., and to develop a methodof routinely identifying triploids in this species. Triploids were produced in all heat-shocked batches and were identified by the size of their erythrocyte nucleus, which had a volume ratio of 1:1-57 relative to diploid controls. Cytogenetic and flow cytometric analyses confirmed that trout with the larger nuclei were triploid. Heat shock of 28°Cof 10 min duration initiated 5-15 min post-insemination produced high rates of triploidy in experimental batches (88-2-100%), later shocks at 20-25 min producing lower rates (down to 60%). Reproducibilicy of tripioid rates was generally good, a maximum difference between replicates of 21.9% being observed, the majority of differences being considerably less. The highest triploid yield was produced with a heat shock of 28°C for 10 min initiated at 10 or 20 min post-insemination, the difference between replicates being due to variability in survival to hatch. Survival to hatch was generally lower in groups having higher rates of tripioidy.  相似文献   

3.
Abstract.— Induction of triploidy and tetraploidy in Nile tilapia, Oreochromis niloticus , was investigated by heat shock, cold shock, hydrostatic pressure, and/or chemicals (cytochalasin A, B, and D). Additionally, efficacy of combined protocols was determined. Heat shock 10 min after fertilization induced triploidy when incubation temperature was 24 C but not when incubation temperature was 31 C. Heat shock of 40–41 C at 4–6 min after fertilization was effective in inducing up to 100% triploidy with hatchability similar to controls. Cold shock at 13 C for 45 min five min after fertilization induced 85–100% triploids. Heat shock and multiple heat shocking were the most effective treatments for the induction of tetraploidy. Two heat treatments of 41 C applied at 65 and 80 min after fertilization for 5 min each produced approximately 80% tetraploidy in hatched fry. Immersion of fertilized eggs in cytochalasin A, B, or D at concentrations up to 10 μg/L applied at various times and durations was ineffective in inducing triploidy or tetraploidy.  相似文献   

4.
Triploidy was induced in the turbot (Scophthalmus maximus, L.) by applying cold shocks shortly after fertilization. The combined effects of the timing of cold shock commencement after fertilization, cold shock duration and cold shock temperature were investigated. Ploidy was assessed by counting the number of nucleoli per nucleus (NOR) in larvae and also by measuring erythrocyte size in juveniles. A clear peak in triploidy induction was obtained when shocks were started between 6 and 7 min after fertilization at a pre-shock temperature of 13–14°C. With this timing, shocks of 20-min duration at 0°C gave >90% triploidy, with survival about 80% of the untreated controls. In order to ensure both high triploidy rates and high survival, it was necessary to carefully maintain the water temperature just below 0°C. Experiments with small and large volumes of eggs were performed in order to determine how changes in the relative volumes of eggs and chilled water could affect survival and triploidy induction. The best combination to induce triploidy in the turbot was as follows: shock commencement 6.5 min after fertilization, shock duration 25 min, and shock temperature between 0 and −1°C. With this combination, 100% triploidy could consistently be induced with survival 60% of the untreated control. This was successfully applied to a large volume of eggs (300 ml; 1 ml 800 eggs) in order to mass-produce triploid turbot. Triploids had lower survival rate than diploids at hatching but similar thereafter, with the ability to complete the different stages of larval rearing, indicating the viability to produce triploid turbot under farming conditions.  相似文献   

5.
The effects of thermal treatments on induction of triploidy in Atlantic cod have been investigated. Cold shock [−1.7±0.1°C at 20 min post fertilization (PF) for 2 h] was based on a previously developed protocol, and heat shocks, below the lethal threshold of 24°C, were at 16, 18 or 20°C applied 20, 30 or 40 min PF for 20 min. Cold shock did not affect larval survival and was ineffective for producing triploids (range 0–4%). A heat shock of 20°C at 20 min PF generated the highest percentages (range 66–100%) of triploid larvae at hatching, with survival ranging from 10% to 20% relative to the controls. Lower heat shock temperatures or delayed shocks increased survival but decreased the number of triploids, providing no net gain in triploid yield (range 1–9%). Heat shocks applied later than 20 min PF produced 2–4% tetraploid larvae at hatching. A thermal shock of 20°C initiated at 20 min PF and lasting 20 min proved to be the most generally efficient treatment for induction of triploidy in Atlantic cod.  相似文献   

6.
Conditions for the induction of triploidy with cold shock of fertilized eggs of the spotted sand bass Paralabrax maculatofasciatus (Steindachner) were investigated. Different temperatures (12, 8 and 4 °C), timing of cold shock application (5, 10 and 15 min after fertilization) and duration of the shock (5, 10, 15 and 20 min) were tested. Triploidy was determined using flow cytometry at 12 h after larvae hatched. Triploids were produced only when the cold shock treatment was applied 5 min after fertilization. No significant difference was observed in the percentage of triploidy between temperature and the shock duration. At 8 and 4 °C, 100% triploidy was obtained at different durations of cold shock. Survival was significantly lower at 12 or 4 °C than at 8 °C. No significant difference was observed for shock duration at the temperature of 8 or 12 °C; however, at 4 °C, survival was significantly lower at longer durations. We recommend induction of triploidy by applying cold shock at 8 °C for a duration of 15–20 min starting at 5 min after fertilization, in the spotted sand bass.  相似文献   

7.
This study was made to optimize heat shock conditions for producing triploidy in the brown trout, Salmo trutta. Heat shock at 29°C for 10 min duration, initiated between 5 and 45 min after insemination, gave high frequencies of triploid embryos (77–91%) as assessed by chromosome observation. Shocks initiated between 90 and 260 min following insemination had no effect on polyploidization. Other groups heat shocked at 29°C for 5–15 min duration initiated 10 min after insemination resulted in moderate rates of triploidy (50–63%). A high temperature shock of 32°C for 6 min duration gave 100% triploidy but a lower temperature shock of 26°C, even for 30 min duration, had only a moderate effect (57%). Rates of hatching were generally decreased in the groups giving moderate to high frequencies of triploidy. In most treated lots haploid embryos were observed and were considered to be a cause of decreased survival.  相似文献   

8.
Triploidy in fertilized eggs of Penaeus semisulcatus was induced by temperature and chemical shocks. The eggs, which were obtained from the shrimp broodstock maintained at 29 C, were exposed to cold temperature (8, 10, 12, and 14 C) and 6‐dimetiloaminopurine (6‐DMAP) concentrations (100, 150, 200, and 250 μM) for different durations (4, 6, and 8 min) 9 min after spawning was detected. While the highest triploidy rate of 49.7 ± 4.5% was obtained with a 200 μM 6‐DMAP concentration for a duration of 8 min, the best mean triploidy rate of 45.5 ± 2.8% for cold shock was obtained at a temperature of 10 C for a duration of 8 min. Temperature and 6‐DMAP concentration did not have significant effect on triploidy rate (P > 0.05) but shock duration had significant effect on triploidy rate for individual cold temperature shock or 6‐DMAP chemical shock (P < 0.05). Although longer durations of shock agent increased the rates of triploid induction, they generally had an adverse effect on hatching rates in the study.  相似文献   

9.
Induction of triploidy and tetraploidy was attempted in Heteropneustes fossilis using heat shock. The optimal age of zygote, temperature level and duration of thermal shock required for effective induction of triploidy and tetraploidy was investigated in a series of experiments. A maximum of 82±7% triploids (3n=87) were obtained when fertilized eggs (2.5‐min old) were heat shocked at 40°C for 4‐min duration. A maximum of 40±8% tetraploids (4n=116) was obtained when the fertilized eggs (30‐min old) were heat shocked at 40°C for 4‐min duration. The triploid and tetraploid red blood cells (RBCs) nucleus volumes were 1.4 and 2.1 times greater, respectively, than that of the diploid RBC nucleus.  相似文献   

10.
《水生生物资源》2003,16(2):90-94
In Eurasian perch (Perca fluviatilis), females grow significantly faster than males. Moreover, gonadal development has a significant negative impact on somatic growth and fillet yield. In order to induce sterility, triploidy induction was attempted by subjecting fertilised eggs to heat shocks. Different combinations of temperature (28, 30, 34, 35 and 36 °C), duration (2, 5, 10 and 25 min) and time of shock initiation (TI = 3, 5 and 7 min post-fertilisation) were tested. Flow cytometry analysis was used to assess ploidy level of control and heat-shocked larvae. Low intensity (28–30 °C) and long duration (10 and 25 min) shocks lead to significantly higher survival (44 ± 26%) and triploidisation (71 ± 26%) rates than high intensity (34–36 °C) and short duration (2 and 5 min) shocks (17 ± 19% and 21 ± 26%, respectively). The most effective conditions for efficient triploidy induction were low intensity shock of 30 °C, applied 5 min post-fertilisation for 25 min. This treatment led to the production of all-triploid populations (100%) with up to 43% survival rate.  相似文献   

11.
The present study was aimed at the identification of treatment optima to induce triploidy in ‘Labeo rohita (rohu) × Cirrhinus cirrhosus (mrigal)’ hybrid using heat shock treatment. The eggs were exposed at four different temperature regimes viz., 38, 39, 40 and 41°C for 1–3 min, applied 3–5 min after fertilization. After 4 min of fertilization, heat shock treatments for 1 and 1.5 min durations were found the best inducing triploidy up to 100% and 96% respectively. Survival rates upto yolk sac absorption were found to be 73% and 71% in rohu and mrigal, 68% and 67% in the reciprocal diploid hybrids and 61% and 60% in the reciprocal triploid hybrids (RTH). Triploidy was confirmed by chromosome counting that revealed the diploid chromosome number of rohu and mrigal at 2n = 50 and in their triploid hybrid chromosome number was found to be 3n = 75. Growth rate of the RTH showed a significant difference (P < 0.05) from the single species and the diploid hybrids. Triploids also showed higher survival rate over the diploids.  相似文献   

12.
Pressure Induced Triploidy in Hybrid Lepomis   总被引：1，自引：0，他引：1  
Worldwide expansion of aquaculture will require identification of species more adapted to localized conditions and less likely to affect genetic diversity of natural populations in the event of escape. Hybrids of Lepomis sunfish have the potential as an alternative for aquaculture in regions of North America where the growing season is unsuitable for production of traditional coldwater and warm-water species. Triploidy was induced in hybrids of green sunfish Lepomis cyanellus males and bluegill L. macrochirus females using hydrostatic pressure shocks. A total of 27 combinations of pressure (41,369, 48,264, and 55,158 kPa), duration (2, 3, 4 min), and post-fertilization time of shock initiation (2, 3, 4 min) were tested to identify those which were most efficient for inducing triploidy. Several of the shock regimes produced 100% triploid hybrid sunfish with at least 90% survival relative to unshocked controls. The two shock treatments deemed best overall were: 1) 48,264 kPa for 4 min begun 2 min after fertilization; and 2) 41,369 kPa for 2 min begun 3 min after fertilization.  相似文献   

13.
Abstract. Triploidy was induced in the fighting fish, Betta splendens Regan, by varying all possible combinations of temperature (37-41°C), time after insemination (2-3min)and shock duration (2-4 min). Heat shock at 39°C for 3 min duration initiated 2-5 min after insemination gave high frequencies of triploids (86%) as assessed from chromosome number and red blood cell nuclear volume. There was no significant difference in the growth rate of triploid and diploid fish. Gonadal development in both sexes was retarded in triploids at 5 months of age. Eggs fertilized with milt from triploids developed to gastrulation. Beyond gastrulation there was increasing mortality associated with abnormalities and none of them hatched. The display frequencies of air gulping, erection of operculum and fins, striking and biting, and undulating movements were fewer in triploids compared to diploids. It appears that triploids are less aggressive than diploids. The aggressive behaviour of fighting fish may be related Io their reproductive activity.  相似文献   

14.
Interspecific allo-tetraploidy was induced by a combination of hybridization of Megalobrama amblycephala ♀× Megalobrama terminalis ♂ and thermal shock. A thermal shock at 40 °C for 2 min applied to eggs 33 or 26 min (τ0: 1.40) after fertilization resulted in a significantly ( P <0.01) higher yield of allo-tetraploids than hybrid crosses without heat shock. The yield of allo-tetraploids in embryos from mid-gastrula to hatching stages was 15.7–24.4% in different thermal shock treatment groups. The allo-tetraploidy rate in 330-day-old juveniles was 9.3% and 6.7% in different year treatment groups. After 2 years of rearing, allo-tetraploidy males attained sexual maturity with milk-like milt at the age of 2+, while allo-tetraploidy females at the age of 2+, and even at 3+, did not show any signs of sexual maturation exhibiting obviously delayed maturity. Only a few allo-tetraploidy females (three individuals) showed maturation characters at the age of 4+ and these females were induced to spawn.  相似文献   

15.
Heat shock was applied to fertilized eggs of European catfish, Silurus glanis L., for the induction of triploidy. A heat shock of 40. 5°C lasting 1 min and starting 9 min after gamete activation gave the best results with 88.93% of hatched viable fry (92.41% in control group). Yields of hatched viable triploid fry reached 63.14% or 50.60%, when expressed as percentage of the absolute number of viable fry or number of living eggs in eye-bud stage, respectively (P < 0.05).  相似文献   

16.
Production of sterile triploid red tilapia [Oreochromis mossambicus (Mozambique tilapia); Peters, 1852 × Oreochromis niloticus (Nile tilapia); Linnaeus, 1758] is an effective strategy to overcome their prolific breeding. Optimal conditions for cold-shock induction of triploidy in red tilapia were investigated by experimentally examining two variables: appropriate temperature of the shock and duration of shock treatment. A constant time after insemination of 4 min was used to determine the best combination of temperature (6, 7, 8, 9, 11, 13, 15 °C) with different durations of shock (10, 20, 30, 40, 50 min) with resultant ploidy level verified karyotypically. Shock duration for 30 min at a temperature of 9 °C was found most effective in producing maximum triploidy (98.7 %) with higher rates of hatching (63.2 %) and survival up to yolk-sac stage (75.8 %). The chromosome count confirmed that triploid percentages were higher when cold shock was used for longer durations at each temperature; however, hatching rates were generally decreased. The maximum triploid yield (82.1 %) obtained was higher than the yield obtained using heat shock (72.7 %) in red tilapia previously. The application of the results of this study has the potential to greatly improve the production of triploid red tilapia in commercial aquaculture.  相似文献   

17.
Naturally spawned Sydney rock oysters Saccostrea commercialis (Iredale and Roughley),were used to determine the appropriate stage of development for inducing triploidy and to compare the effectiveness of cytochalasin B (CB) and 6-dimethylaminopurine (6-DMAP) in dose-optimization trials. Induction should commence at 50% first polar body (PB1) extrusion in eggs (approximately 17-19 min post-fertilization at 25oC). By day 5 the highest triploidy percentage and yield (number of triploid larvae per 100 fertilized eggs) were achieved in the ranges of 0.75-1.5 mg CB 1-1 (1.6-3.1 μm CB)or 200-400 μm 6-DMAP (32.6-65.3 mg 6-DMAP l-1). However, CB treatment resulted in greater survival and triploidy percentage than 6-DMAP in Sydney rock oysters.  相似文献   

18.
Optimal conditions of 6‐dimethylaminopurine (6‐DMAP) for triploidy induction in the blacklip abalone Haliotis rubra (Leach, 1814) were investigated, targeting inhibition of second polar body (PB2) formation. Two experiments were conducted at a water temperature of 17.5–18.5°C where factorial combination of (1) four dosages (DSs) of 100, 150, 200 and 250 μM 6‐DMAP, four starting times (STs) of 15, 20, 25 and 30 min post fertilization, and two treatment durations (TDs) of 20 and 30 min and (2) three DSs of 50, 100 and 150 μM 6‐DMAP, three STs of 15, 20 and 25 min post fertilization, and three TDs of 10, 20 and 30 min, were applied respectively. Day 3 larvae were sampled for triploidy and survival. Percent triploidy was verified using flow cytometry (FCM). Results show that optimal inductions that combine both high rates of triploidy and reasonable survival were those treatments commenced 15 or 20 min post fertilization and continued for 20 or 30 min, using 100 μM 6‐DMAP. These conditions induced rates of triploidy and relative survival of 80.5–93.3% and 36.5–40.2%, respectively, in the first experiment, and corresponding rates were 79.1–93.6% and 20.7–43.0% in the second experiment. High percent triploidy were also obtained in a number of treatments using 150 μM 6‐DMAP, but with overall survival rates generally lower than those using 100 μM 6‐DMAP.  相似文献   

19.
Heat shocks, hydrostatic pressure shocks, and ultraviolet radiation were evaluated for their efficacy as methods of manipulating ploidy in yellow perch (Perca flavescens). The most effective methods of inducing triploidy were heat shocks of 28–30°C applied at a time of initiation (TI) of 5 min postfertilization for durations of 10 or 25 min, and hydrostatic pressure shocks of 9000 or 11 000 psi applied at a TI of 5 min for a duration of 12 min. These treatments resulted in triploidy induction rates that ranged from 54–100%, and embryonic survival rates of 16–80%. Cold shocks of 0°C had no effect on the ploidy or survival of embryos. For perch, hydrostatic pressure shock offered several advantages over heat shock as a method of manipulating ploidy. The most effective methods of inducing tetraploidy were hydrostatic pressure shocks of 9000 psi applied at a TI of 192 min for durations of 16 or 24 min. Ultraviolet radiation of perch sperm with doses of 3240–6480 ergs/mm2 resulted in 100% inactivation of paternal chromosomes, and perch eggs fertilized with inactivated sperm had survival rates of > 50%, thereby establishing methods for producing gynogenetic perch. Studies comparing the growth and performance of diploid vs. triploid perch are underway. Tetraploid perch are being reared to sexual maturity to evaluate their potential as brood fish.  相似文献   

20.
静水压休克法诱导三倍体鲶鱼（silurus asotus L）的研究   总被引：1，自引：0，他引：1  
采用静水压休克法诱导三倍体鲶鱼。通过对受精时间、静水压力及持续施压处理时间三方面进行筛选试验的结果表明，鲶鱼卵受精4－5min，用600－649kg/cm^2的静水压力处理3min，可以获得100％的三倍体鲶鱼，而且胚胎存活率也较高，孵化率达对照组的90％以上，是静水压休克法诱导三倍体鲶鱼的最佳条件。三倍体鲶鱼的倍性用细胞遗传学方法验证。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号