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1.
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   

2.
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   

3.
CB诱导熊本牡蛎三倍体及其存活率与倍化率的变化关系   总被引：2，自引：1，他引：1  
为诱导熊本牡蛎三倍体,研究了细胞松弛素B (CB)浓度、诱导起始时间、诱导持续时间等因素对卵裂率、D幼率、三倍体率的影响,并分析了幼虫、稚贝及成贝的存活率和三倍体率的变化特征。结果显示,CB浓度为0.5~0.6 mg/L,诱导起始时间为40%受精卵释放第一极体,诱导持续时间为20 min时可获得87%的三倍体率。卵裂率、D幼率、三倍体率的最大影响因素分别为CB浓度、诱导持续时间、诱导起始时间与诱导持续时间。三倍体率与卵裂率无显著负相关性,而与D幼率呈显著正相关。因此,减小CB浓度或诱导持续时间,可同时获得较高的三倍体率与幼虫产量。3~15日龄三倍体组与对照组的存活率分别由71.27%与96.09%降低至34.14%与58.80%,成贝期450日龄(9月)三倍体组与对照组的存活率分别为53.62%与44.67%。3~9日龄三倍体率从87%降低至77%,而90~450日龄三倍体率平均值为59.21%±4.99%,表明幼贝与成贝期三倍体率变化较小,三倍体率的维持与存活率无显著相关性。  相似文献   

4.
Triploid induction in Australian greenlip abalone, Haliotis laevigata (Donovan), was conducted by blocking the formation of the second polar body using cytochalasin B (CB). Twenty minutes after fertilization, the zygotes of greenlip abalone were treated with four CB concentrations (0, 0.25, 0.5 and 0.75 mg L−1) for 10, 15 and 20 min. The ploidy of resultant larvae was determined using flow cytometry at 72-h post fertilization. Our study showed that fertilization, hatching, survival and induced triploidy of abalone larvae were significantly affected by the CB concentration and treatment duration. The effective range of CB concentration for triploid induction on greenlip abalone was 0.5–0.75 mg L−1 with an induction duration of 10–15 min. The results indicate that the most effective treatment combination for triploid induction in greenlip abalone is 0.5 mg CB L−1 for 15 min starting at 20-min post fertilization.  相似文献   

5.
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   

6.
Induction of triploidy in the South African abalone using cytochalasin B   总被引：2，自引：0，他引：2  
An investigation into triploidy induction in the South African abalone, Haliotis midae, was conducted. It was found that 0.5 mg l–1 of Cytochalasin B (CB) in seawater induced triploidy when administered to coincide with the normal timing of the release of either polar body one (PB1) or two (PB2). This concentration of CB produced 70.9% triploid induction in the PB2 treatment and 48.4% induction at PB1. Significant numbers of tetraploid larvae were found in the PB1 treatment. These resulted from the presence of excess sperm (polyspermy) but only when CB was present. Although larval survival after triploid induction was lower than the control animals, it was considered high enough for use in commercial hatcheries. © Rapid Science Ltd. 1998  相似文献   

7.
不同方法制备的三倍体长牡蛎养殖效果的比较   总被引：9，自引：1，他引：8  
张国范 《水产学报》2000,24(4):324-328
比较了细胞松弛素B(CB)和6-二甲基氨基嘌呤(6-DMAP)通过抑制受精卵极体释放的方法批量诱导三倍体长牡蛎的养殖效果.长牡蛎卵子在25℃的海水中受精,20～30min后,开始用浓度为0.5mg@L-1的CB处理,持续18～22min,受精卵处理密度为4.0～4.5×107个@L-1,三倍体产率为65.2%～70.1%,面盘幼虫孵化率为12.3%～14.5%,诱导效率指数为0.09.6-DMAP的使用浓度为400～420μmol@L-1,受精卵处理密度为3.0～3.5×107个@L-1,授精水温、处理起始和持续时间等与CB方法相同,三倍体产率为58.7%～65.4%,面盘幼虫孵化率为52.1%～55.4%,诱导效率指数为0.32.两种方法的采苗率基本相同,采苗器为基质较硬的栉孔扇贝贝壳.海区养殖采用浮筏夹苗吊养技术,两种方法诱导的三倍体牡蛎养殖性状没有明显差别.通过比较CB和6-DMAP两种诱导方法及三倍体的养殖效果表明,后者具有更好的应用性.  相似文献   

8.
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   

9.
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   

10.
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   

11.
Abstract. For the first time, effective treatments using cytochalasin B were developed to induce triploidy in the European clam, Ruditapes decussatus (L.). The percentage of triploid embryos was assessed by karyological or image analysis. Two treatments (0·5 or 1 mg of cytochatasin B (CB) per ml of dimethyisulfoxide in 1 litre of sea water) were applied at different times after fertilization (10 to 25min), for two different periods (15 and 20min). Best results were obtained for a CB concentration of 1 mg/1. When treatment was applied 15min after fertilization for a 20min period, 94% and 95% of triploid embyros were obtained in two repeated experiments. At metamorphosis, the treated larvae appeared to be no smaller than the control larvae in all experiments. However, in general, significantly higher mortalities for CB-treated batches were found when compared with the untreated batch.  相似文献   

12.
The aim of the present study was to produce Acipenser baeri× (Huso huso×Acipenser ruthenus) hybrids in a diploid and triploid state and to study their viability in comparison with the A. baeri from the fish farm stock. A heat shock (37°C) in the 18th minute after fertilization was applied to induce triploidy. The survival rate and the ploidy level of the hybrids obtained were studied. The mortality of triploid hybrids was approximately twice as high as the mortality of diploid hybrids. No significant difference in the survival rate between Siberian sturgeon and their diploid hybrid with bester was noted. Cytogenetic analysis was performed by preparing chromosomes from the gill epithelium. The results showed that all studied fish from the heat‐shocked group were triploid.  相似文献   

13.
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   

14.
The triploid technology is a new frontier in shellfish aquaculture and has shown encouraging results in numerous shellfish species. We induced triploid larvae in the Yesso scallop, Patinopecten yessoensis, using hyperosmotic shock for the first time in this study. Different induction parameters, including salinity strength, treatment starting point, and the duration, were tested. The highest triploid ratio of D‐shaped larvae (72.12%) was obtained by 60 ppt salinity treatment for 20 min at the first appearance of zygote showing polar body II (PB2). A significantly faster growth rate was observed during the swimming larvae stage despite a decrease in the hatching and survival ratios. The triploid ratio decreased to 46.67%, and approximately 1.76 million triploid juveniles were harvested after 90 days of cultivation. The treatment parameters can be further optimized to improve the yield of Yesso scallop triploids.  相似文献   

15.
Triploidy was induced in Crassostrea gigas using cytochalasin B (CB) (1 mg CB/l) at three temperatures: 18, 20 and 25°C. Between 3 and 5 million eggs/l were treated with CB at 15-min intervals following fertilization.Large differences in survival to straight hinge among mass spawns were observed. These were attributed to variable quality of strip-spawned eggs and treatment with CB. The negative effect of CB treatment was most apparent during critical periods of zygotic development (e.g., fertilization, polar body formation). After 48h, larvae from control and treatment groups had equivalent survival and growth rates.Replicates yielded similar percentages of triploids with standard errors of generally 10% or less. Induction curves were calculated for each temperature; triploid maxima at 18, 20 and 25°C were 52, 76 and 90%, respectively. The highest mean percentages obtained empirically at 18, 20 and 25°C were 62, 74 and 88%, respectively. No evidence for bimodal distributions to separate meiotic I and meiotic II triploids was found. Treatments at lower temperatures delayed triploid maxima which occurred approximately 30, 45 and 50 min after fertilization at 25, 20 and 18°C, respectively. Overall, the optimal treatment for inducing triploidy in the Pacific oyster (C. gigas) appears to be 30–45 min post-fertilization at 25°C, which yielded 88±9% (SE) triploidy over four replicates.  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.
The precociously sexual maturation in large yellow crocker Pseudosciaena crocea has become a serious problem. In an attempt to solve this problem, the production of sterile triploids could be an effective strategy. In this study, triploid P. crocea was obtained by subjecting fertilized eggs to pressure shock. Flow‐cytometry analysis was used to assess ploidy level. In terms of triploid rate and hatching rate, the optimal conditions of pressure shock for triploidy induction in P. crocea were 7500 psi for 3 min shock at 3 min after fertilization at 20 °C. With the application of these parameters, 100% triploid fish were produced. During the first rearing year, triploid P. crocea had a similar growth performance compared with its diploid counterpart before the age of 8 months and showed a significant advantage at the age of 10 and 12 months in body weight and body length (P<0.05). At the age of 12 months, the carcass weight of triploids was markedly higher than that of diploid control, and gonadal somatic index was significantly lower than that of their diploid control. During the first rearing year, survival in triploid group was 76.44%, inferior to its diploid control (83.21%).  相似文献   

18.
The effectiveness of cytochalasin B (CB) treatments for inducing triploidy was evaluated in the blacklip abalone Haliotis rubra (Leach, 1814) in two orthogonal design experiments. The first experiment employed three dosages (DSs) of 0.25, 0.5 and 1.0 mg CB L?1, three starting times (STs) of 5, 15 and25 min post fertilization and three treatment durations (TDs) of 10, 20 and 40 min, for a total of 27 treatments. The second experiment comprised of two DSs of 0.25 and 0.5 mg CB L?1, five STs of 5, 15, 20, 25and 30 min post fertilization, and three TDs of 10, 20 and 40 min, for a total of 30 treatments. Water temperature was held at 17.5–18.5°C. Day 3 larvae were sampled for triploidy using flow cytometry (FCM) and survival. Optimal inductions were treatments starting at 15 or 20 min post fertilization and continuing for 40 min, and those initiated 25 or 30 min post fertilization for 20 or 40 min, using 0.5 mg CB L?1. These treatments were all targeted at inhibition of the second polar body (PB2) formation and yielded triploidy rates of 84.8–89.5% coupled with (relative) survival rates of 20.1–52.1% in the first experiment, and corresponding rates of 86.5–96.5% and 33.0–74.1%, respectively, in the second experiment. A common and essential feature of these optimal conditions is that treatment must fully span the period of time for most of the eggs to extrude PB2. Treatments that resulted in suppression of the first polar body (PB1) formation induced triploidy levels below 71.5% and 57.6% in experiments 1 and 2 respectively. Treatments that had overlapping effects on both PB1 and PB2 extrusion led to triploidy rates above 80% but very low survival rates of 1.8% and 5.4% in experiments 1 and 2 respectively.  相似文献   

19.
In this study, the effects of three commonly used chemicals, dimethyl sulphoxide (DMSO), ethylene glycol (EG), propylene glycol (PG) and their combinations with trehalose, were evaluated on the cryopreservation of D‐larvae of the blue mussel Mytilus galloprovincialis. The larvae were harvested 30 h post‐fertilization at 21 °C and cryopreserved using a standard protocol in 5%, 10% or 15% of DSMO, EG and PG either as single chemical solutions or in combination with 0.2 M trehalose. Among these cryoprotectants, 5% DMSO resulted in the highest post‐thaw survival rate of 55.3±7.8%, although it did not significantly differ from those with 10% and 15% EG. The addition of 0.2 M trehalose did not improve the post‐thaw larval survival rates in all the combinations assessed. The cryo‐effects on subsequent development were evaluated using the D‐larvae frozen with 5% DMSO. The results showed that cryopreservation affected both larval survival and growth in this species. The relative daily mortality rate was significantly higher in treated than control groups over the period from 3 h post‐thaw to day 11 post‐fertilization. On day 6 post‐fertilization, the average larval length in the treated group was significantly smaller than that in the control. From day 11 post‐fertilization, and onwards, differences in these two traits were not significant between treated and control groups. On day 21 post‐fertilization, about 80% of the larvae in both treated and control groups developed eyes and the normalized survival rate in the treated group was 12.5%.  相似文献   

20.
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   

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