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1.
A novel marine origin Bacillus subtilis strain H1 isolated from a shrimp culture pond effectively removed NH4+‐N, ‐N and ‐N, with a maximum ammonium, nitrite and nitrate removal rate of 2.35 mg NH4+‐N L?1 hr?1 per OD, 9.64 mg ‐N L?1 hr?1 per OD and 0.75 mg ‐N L?1 hr?1 respectively. The gas chromatography–isotope ratio mass spectrometry results indicated that N2O was emitted when 15NH4Cl, Na15NO2 or Na15NO3 was used. Additionally, N2 was also produced when Na15NO2 was used. Single‐factor experiments suggested that the optimal conditions for NH4+‐N and ‐N removal were glucose as a carbon source, C/N 15, initial pH 7.5, 30 g/L NaCl, 28°C and a shaking speed of 160 rpm. Orthogonal tests showed that the optimal conditions for NH4+‐N removal were C/N 15, pH 9, 10 g/L NaCl and shaking speed 160 rpm when ammonium chloride was used as the substrate. The optimal conditions for ‐N removal were C/N 10, pH 6, 10 g/L NaCl and a shaking speed of 160 rpm when sodium nitrite was used as the substrate. In summary, B. subtilis strain H1 had highly efficient aerobic nitrifying–denitrifying ability and high adaptability, suggesting that it is potentially valuable to marine aquaculture.  相似文献   

2.
Nitrogen and Phosphorus are the major end products of fish feed loading and affect the water environment as a whole. A magnetic stirrer was used to simulate the intensity of water flow by using different stirring strengths (0, 600, 1,200 rpm), and kinetic experiments on nutrients release from different fish feed (0.2500 and 0.5000 g) were performed. Results have shown that total phosphorus (TP) increase rapidly and become stable in about 96 hr, while orthophosphate ( ), total nitrogen (TN) and ammonia nitrogen ( ) increase relatively slowly and gradually reach stable from 200, 300 and 300 hr respectively. Both released contents of unit weight fish feed (i.e. released nutrients contents) and released nutrients concentrations in the condition of stirring were higher than those in the static condition. All of the pseudo‐first‐order, pseudo‐second‐order and Elovich kinetic models can be used to describe variations of released TP, , TN and contents with time, while the pseudo‐first‐order kinetic and Elovich kinetic models give better results with R2 = .66–.99 and R2 = .57–.99 respectively. Variance analysis showed that both stirring strength and fish feed type have significant effects on released TP, TN and contents (p < .05), while fish feed dosage has no significant effects (p > .05). In addition, only the fish feed type does have significant effects on contents (p < .05). In sum, the release kinetics and the factors related to the release of nutrients from fish feed are essential in planning strategies of nutrient management and pollution control.  相似文献   

3.
The effects of body and meals sizes on gastric evacuation (GE) of the endangered Siberian sturgeon (Acipenser baerii) were parameterized (at temperatures ranging from 16.8 to 17.6°C) using radiography technique. GE experiments were performed using different body sizes A. baerii ranged from 1.5 kg to 5 kg fed on meal sizes of 4.6 g to 47.6 g composed of either commercial pellets or live food (fish prey, whiting). The commercial pellets used in these experiments had barium sulphate at concentrations of 20%, while the same amount was injected into the body of live food for radiography technique monitoring. The course of GE in A. baerii was best described by the square root model independently of meal size. The effects of body mass and temperature on GE rates were described by power model and simple exponential model respectively. GE rates of A. baerii fed on live food could be summarized by (g/hr), while for commercial pellets, where St is the stomach contents mass (g), W is fish wet weight (cm), T is temperature (°C), and t is time (hr). These summarized models could estimate the time required for a meal to be evacuated from the stomach of A. baerii or determine the stomach fullness at postprandial time t. These results will assess the planning of feeding regime for A. baerii to avoid their overfeeding and underfeeding.  相似文献   

4.
Studies on chronic or acute toxicity of nitrogen species on fish in recirculating aquaculture systems (RAS) usually focused on adverse effects of total ammonia nitrogen (TAN: sum of NH3 + NH4+) and nitrite (), while underestimating the potential effects of high nitrate accumulation on growth and health status of fish. In our study, Nile tilapia (Oreochromis niloticus) were exposed to five different nitrate concentrations (0, 10, 100, 500 and 1000 mg L?1 ‐N) over 30 days. Growth parameters (feed conversion ratio (FCR), specific growth rate (SGR), hepatosomatic index (HSI)), blood samples (concentrations of haemoglobin, methaemoglobin, plasma /) and the histology of the gills were studied to evaluate growth and health status of the fish. At the highest nitrate concentration, the fish showed significantly reduced growth and impaired health status (SGR, FCR, plasma /, haemoglobin and methaemoglobin concentration), demonstrating that too high nitrate concentrations can negatively influence tilapia production in RAS. Here, we recommend not exceeding concentrations of 500 mg L?1 ‐N in juvenile tilapia culture to ensure an optimal health and growth status of the fish, as below that concentration no effects on the tilapia have been observed.  相似文献   

5.
Cannibalism is frequently observed in larviculture of orange‐spotted grouper Epinephelus coioides. Previously, based on measurements of morphometric characters, a linear equation of total length (TL) of prey to cannibals was proposed: TLprey = 0.80 TLcannibal – 1.50. To verify the reliability of the equation, experiments were performed with pairs of fish with different TLs. Cannibalism occurred only when the cannibal‐prey size ratios were equal to or larger than that predicted by the equation. To predict the probability of cannibalism among the grouper of known TLs, a logistic regression model was proposed. The logistic regression model is: The logistic regression model showed the following: when either TLprey or TLcannibal is constant, the probability of cannibalism increases with increase in the cannibal‐prey size ratios; if given a constant cannibal‐prey size ratio, probability of cannibalism is lower in early stages than in later stages. The prediction contrasts with that calculated from the linear equation where the minimum cannibal‐prey size ratios decrease with size of the cannibal. However, the prediction matches observed rearing experiences: cannibals prefer smaller prey to larger ones and the cannibalism rate declines as fry age.  相似文献   

6.
Cyprinid herpesvirus 3 (CyHV‐3) or koi herpesvirus (KHV) is a virulent viral infection in common carp and koi. The disease has caused global epizootic and economic loss in fish aquaculture and in the wild. Clinacanthus nutans (Burm. f.) Lindau is a well‐known medicinal plant used in Thai traditional medicine. Virucidal effects of the plant extract against human herpes simplex virus have been reported. In this study, C. nutans crude extract was tested for antiviral activities against CyHV‐3 in koi carp. Results showed effective antiviral activity against CyHV‐3 pre‐ and post‐infection. The 50% lethal concentration (LC50) of extract was higher than 5 mg/ml. The 50% effective dose (ED50) was 0.99 mg/ml, 0.78 mg/ml, 0.75 mg/ml and 0.71 mg/ml at 1, 2, 3 and 4 hr pre‐infection, respectively. The ED50 from post‐infection tests was 2.05 mg/ml and 2.34 mg/ml at 0 and 24 hr, respectively. These results demonstrated that crude extract expressed antiviral activity against CyHV‐3 and can be applied as a therapeutic agent in common carp and koi aquaculture.  相似文献   

7.
The Channel Catfish Ictalurus punctatus is an important ecological, recreational and aquaculture species. In both natural and pond culture systems, Channel Catfish are periodically exposed to acute increase in temperature, especially in the summer, which may induce a stress response. With the effects of global climate change, the impact of rising temperatures on aquatic systems is expected to be exacerbated in the future. Hence, there is the need to understand the physiological mechanisms controlling the thermal stress response in fish. Acid–base, haematological, osmotic and metabolic regulations were investigated following acute temperature increase from 28°C to either 32°C or 36°C at a rate of 2°C/hr to assess the physiological response of Channel Catfish to temperature increase. Blood was sampled 1 hr after treatment temperatures were reached. When temperature increased from 28 to 32°C, blood bicarbonate () decreased while cortisol, partial pressure of carbon dioxide (pCO2) and glucose increased. When temperature increased from 28 to 36°C, blood pH, , chloride, total proteins and mean corpuscular haemoglobin concentration decreased while cortisol, pCO2, haematocrit, haemoglobin, glucose, lactate, mean corpuscular volume and mean corpuscular haemoglobin all increased. The changes observed are characteristic of acute stress responses in fish and suggest that acute temperature increases to both 32 and 36°C are physiologically stressful to Channel Catfish.  相似文献   

8.
A field campaign was conducted around salmon cages, using a combination of a towed ADCP and a free‐fall multi‐parameter profiler, in order to investigate flow structures and the possible distribution of effluent materials. Two transect observations showed that hydrographic conditions changed dramatically within 5 days, from highly stratified open water conditions to weak stratification. Three‐dimensional observation revealed that flow was blocked behind the cages and that the blockage was reduced as the distance from the cages increased. The flow speed was positively correlated with the intensity of the backscattering signal. The R2 value was high immediately behind the cages and decreased with distance from the cages. The flow time series behind the cages exhibited a k–2 power law spectrum that was consistent with a typical internal wave spectrum. This suggests that eddies shed from the cages were highly influenced by stratification. We estimated the rate of kinetic energy dissipation, , from YODA Profiler data based on the Thorpe scale approach. We also estimated the eddy diffusivity coefficient, . Both and followed a lognormal probability density function. The mean was consistent with a one‐dimensional diffusion model assessed from the R2 values of flow speed and backscatter intensity.  相似文献   

9.
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10.
This study assessed the effect of cyclical feeding on compensatory growth, nitrogen (N) and phosphorus (P) budgets of juvenile Litopenaeus vannamei. A 36‐day growth trial was performed with four different feeding protocols. The control group (S0) was fed to satiation twice every day during the whole experimental period; treatment groups S1, S2 and S3 were fed by the 9, 5 and 3 cycles of 1:3, 2:5 and 3:9 (fasting days:feeding days) respectively. Fasting in S1, S2 and S3 groups did not change the specific growth rate in wet weight (SGRw), but the feed conversion efficiency (FCE) and protein efficiency ratio (PER) were significantly increased (P < 0.05) in comparison with control. The N and P consumed per unit wet weight gain of shrimp in S1, S2, S3 groups were significantly lower (P < 0.05) than control group by 15.39%, 15.96%, 19.33% for N, and 15.16%, 15.98%, 19.26% for P respectively. The total discharge of N and P (including N and P discharged by faeces (FN/P), non‐faecal excretions (UN/P) and exuviations (EN/P); ) was significantly lower (P < 0.05) in the experiment groups by 19.91–22.07% for N and 18.68–26.37% for P respectively. Overall, the results suggest that the L. vannamei can reach completely compensatory growth, and the total discharge of N and P per unit wet weight gain of L. vannamei significantly decreased by cyclical feeding, which could have a positive effect on the reduced of environmental N and P loading due to the cultured of L. vannamei.  相似文献   

11.
This study explored the pharmacokinetic characteristics of bronopol in grass carp (Ctenopharyngodon idella) under different temperatures. The concentrations of bronopol in the plasma and tissues (kidney, liver and muscle) of grass carp after soaking in bronopol (6.75 µg/ml) at 15 and 20°C were determined using liquid chromatography–mass spectrometry. The concentrations of bronopol in both plasma and tissue first increased and then decreased with soaking time at both tested temperatures. The peak bronopol concentrations at 15°C (plasma: 8.934 µg/ml; kidney: 9.23 µg/g; liver: 9.47 µg/g; and muscle: 7.98 µg/g) were slightly lower than those at 20°C (plasma: 9.654 µg/ml; kidney: 10.83 µg/g; liver: 13.40 µg/g; and muscle: 8.68 µg/g). In an analysis of pharmacokinetic parameters, the bronopol concentration–time profiles for plasma were best described by a two‐compartment, open pharmacokinetic model with first‐order absorption. The t1/2β for plasma at 15 and 20°C was 82.933 and 92.041 hr, respectively, indicating that the elimination of bronopol was faster at 15°C than at 20°C. In addition, AUC0‐t and AUC0‐∞ values of bronopol were 477.892 and 495.809 µg/L hr at 15°C and 495.809 and 589.859 µg/L hr at 20°C, indicating that the content of bronopol in the organism was higher at higher temperature.  相似文献   

12.
The pharmacokinetics and tissue residues of vancomycin in crucian carp (Carassius auratus) were studied after oral administration of a single dosage of 1 mg/kg body weight at water temperature of 18°C. The drug concentration‐time data were fitted using a two‐compartment open model with first‐order absorption. The vancomycin concentrations in plasma and tissues including muscle, liver and kidney were analyzed by means of liquid chromatography‐tandem mass spectrometry. As a result, the plasma absorption rate constant of vancomycin was 3.75/hr and the time point of maximum concentration in plasma was 3.0 hr respectively. The maximum concentration of vancomycin in plasma was 216.58 μg/L. The distribution half‐life and the elimination half‐life in plasma were 6.69 hr and 190 hr, as well as the absorption half‐life of plasma was 0.19/hr. The area under the plasma concentration‐time curve of plasma was 15.12 mg hr/L. The apparent volume of distribution of plasma was estimated to be 4.45 L/kg and the total body clearance was computed as 0.061 L hr?1 kg?1. In addition, the maximum tissue concentrations of vancomycin were in the order of liver > kidney > muscle. To guarantee the safety of tissue samples for consumption, it was suggested that the withdrawal time should not be less than 30 days at 18°C. All these results may provide guidance for future vancomycin treatment in aquaculture.  相似文献   

13.
The experiments explored the pharmacokinetics (PK) properties of oxolinic acid (OXA) after oral administration at three dosages (10, 30 and 80 mg/kg) via medicated feed in the shrimp. The results showed that the Cmax values of 4.31, 14.93 and 16.62 mg/L and AUC0–∞ values of 92.61, 252.30 and 364.27 mg hr?1 L?1 were observed at three OXA dosage groups in the haemolymph respectively. In the hepatopancreas, Cmax values of 7.90, 27.23 and 60.51 mg/kg and AUC0–∞ values of 42.01, 133.06 and 219.06 mg hr?1 L?1 were observed at 0.5 hr post administration respectively. In the muscle, Cmax values of 1.62, 5.80 and 7.36 mg/kg and the AUC0–∞ values of 25.64, 98.10 and 134.24 mg hr?1 L?1 were observed at 2 hr post administration respectively. In the gills, Cmax values of 2.87, 8.08 and 12.12 mg/kg and the AUC0–∞ values of 51.38, 118.65 and 206.48 mg hr?1 L?1 were observed at 4 hr post administration respectively. In addition, the in vitro MIC values of OXA at three dosages against 132 strains of Vibrio were examined and showed that the minimum inhibitory concentration (MIC) values for OXA primarily ranged from 0.15–1.25 µg/ml, including eight strains of Vibrio showing MIC values ≥5 µg/ml. The MIC50 and MIC90 values of 132 strains were 0.62 and 1.25 μg/ml respectively. The AUC0–24/MIC90 ratios of Vibrio were 140.4 in 30 mg/kg group. Furthermore, the P‐glycoprotein (P‐gp) expression was determined in shrimp tissues after administration to three dosage groups (10, 30 and 80 mg/kg). The results showed that P‐gp expression was up‐regulated in the hepatopancreas (5.36‐, 13.68‐ and 31.06‐fold respectively) compared with the control group.  相似文献   

14.
The objective of this study was conducted to research the effects of β‐conglycinin in the diets on the growth performance, immunity function, antioxidant capacity and intestinal health of juvenile golden crucian carp (Carassius auratus). Five diets contained respectively (0, 20, 40, 60 and 80 g/kg) β‐conglycinin, and were used to feed juvenile golden crucian carp for 56 days. Final weight, weight gain and specific growth rate were significantly reduced by dietary β‐conglycinin (20–80 g/kg). Feed efficiency and protein efficiency were significantly reduced by dietary β‐conglycinin (40–80 g/kg). In hepatopancreas, the activities of T‐SOD, ACP, ALT and T‐AOC were significantly suppressed by dietary β‐conglycinin (20–80 g/kg). The activities of LZM, AKP, CAT and GPx were significantly reduced by dietary β‐conglycinin (40–80 g/kg). The activities of protease were significantly reduced and the content of MDA was significantly increased by dietary β‐conglycinin (60–80 g/kg). In proximal intestines, the activities of protease and CAT were significantly decreased by dietary β‐conglycinin (40–80 g/kg). In mid and distal intestines, the activities of protease and CAT were significantly inhibited by dietary β‐conglycinin (20–80 g/kg). In intestines, T‐AOC and GPx were significantly declined by dietary β‐conglycinin (20–80 g/kg). In proximal and mid intestines, the content of MDA were significantly increased by dietary β‐conglycinin (40–80 g/kg). In distal intestines, the content of MDA was significantly increased by dietary β‐conglycinin (20–80 g/kg). The expression of IGF‐I was significantly decreased and the expression of IL‐1β and TNF‐α was significantly increased by dietary β‐conglycinin (20–80 g/kg). The structural integrity of intestinal tissues were damaged by dietary β‐conglycinin (20–80 g/kg), the part of intestinal villus were shed, the part of epithelial cells were separated from lamina propria. Ultimately, these results suggested dietary β‐conglycinin should be <20 g/kg in formula feed of golden crucian carp.  相似文献   

15.
An experiment was carried to determine the plasma fenbendazole (FBZ) concentration and physio‐metabolic responses in juveniles of Labeo rohita (90 ± 4 g) after oral administration of single doses at 10, 20 and 50 mg, 20 mg FBZ/kg b.wt. in multiple times on 1st, 3rd and 7th day. The blood samples were collected at 0.5, 1, 2, 4, 8, 12, 24, 30, 48, 72, 96 and 120 hr, after single‐dose administration, and regularly (upto 15 day) in multiple dose. Plasma FBZ concentration was determined up to the limit of detection (LoD) of 0.09 µg/ml by HPLC. There was no parent drug detected in plasma for administration of 10 mg FBZ/kg b.wt. The drug attained the peak concentration (Cmax) 1.85 and 3.09 µg/ml in plasma at 4 hr (Tmax) after administration of 20 and 50mg FBZ/kg b.wt. respectively. Plasma FBZ was detectable up to 96 and 120 hr with concentration 0.09 ± 0.007 and 0.098 ± 0.006 µg/ml, respectively, after single‐dose administration of 20 and 50mg/kg b.wt. In case of multiple‐dose administration, the maximum concentration of FBZ was 1.01 ± 0.03 µg/ml on 7th day that was less than to the single dose at 50 mg/kg b.wt. However, FBZ was detected up to 11 day after multiple doses. The study revealed that the hepatic antioxidant enzymes activities like superoxide dismutase, catalase and glutathione‐S‐transferase were significantly affected by increasing FBZ in single and multiple doses. The results of the present study could reveal that single‐ or multiple‐oral administration of FBZ at 20 mg/kg b.wt. in feed as antihelminthic drug in L. rohita could be considered as the safe dose.  相似文献   

16.
This study investigated the effects of glutamate (Glu) in low‐phosphorus diets on growth performance, haematological indices, antioxidant enzyme activity, immune‐related gene expression and resistance to Aeromonas hydrophila in juvenile mirror carp (Cyprinus carpio) (5.07 ± 0.02 g). Fish were fed either graded levels of Glu (0 g/kg, 5 g/kg,  10 g/kg and 20 g/kg, named G0, G0.5, G1 and G2, respectively) in a low‐phosphorus diet (15 g/kg NaH2PO4, 0.49), or a normal phosphorus diet ( 20 g/kg NaH2PO4, 0.61) without added Glu (C), for 8 weeks. At the end of the feeding trial, the fish were challenged with A. hydrophila. Compared with G0 group, 10 g/kg and 20 g/kg Glu supplementation of the low‐phosphorus diet significantly improved the final weight, WGR, SGR and PER, and decreased FCR (p < .05). Glu supplementation of the low‐phosphorus diet significantly enhanced the T‐AOC, SOD activity and GSH content in intestine (p < .05). Glu supplementation significantly reduced MDA content in foregut and midgut and increased CAT activity in midgut and hindgut (p < .05). Regarding immune‐related gene expression, Glu supplementation significantly diminished the up‐regulation of intestinal TNF‐α, IL‐1β and IL‐8 mRNA levels induced by phosphorus deficiency (p < .05). The survival rate of the G1 group was significantly higher than that of the G0 group (p < .05). In conclusion, 10 g/kg Glu supplementation in low‐phosphorus diets can improve the growth performance, enhance the activity of intestinal antioxidant enzymes and strengthen the immune function of juvenile mirror carp.  相似文献   

17.
This study was carried out to evaluate the dietary available phosphorus (AP) requirement for crucian carp (Carassius auratus). Triplicate groups were fed diets containing five graded levels of AP in 15 recirculating tanks. After a 9‐week feeding experiment, weight gain (WG), specific growth rate (SGR), feed efficiency (FE) and whole‐body and vertebrae P contents were significantly increased as dietary AP increased from 1.1 to 7.6 g/kg (p < .05) and then levelled off. N and P retention was also significantly increased as dietary AP increased to 5.5 g/kg (p < .05). Condition factor, viscerosomatic index, hepatosomatic index, whole‐body moisture, muscle P content and plasma total cholesterol were not affected by dietary P levels (p > .05). Protein and ash contents of the whole body increased linearly as the dietary P level increased, but the lipid content, plasma alkaline phosphatase activities and triacylglycerol contents showed an inverse relationship. Based on WG, FE, whole‐body P content and vertebrae P content, the optimum requirement of dietary AP for crucian carp was estimated to be 8.3, 8.3, 8.0 and 7.8 g/Kg, respectively.  相似文献   

18.
A 60‐day feeding trial was conducted to estimate the effects of dietary iron (Fe) levels on growth, Fe concentration in the liver, spleen, and blood, and transferrin and hepcidin concentrations in the blood of bighead carp (Aristichthys nobilis). The six experimental diets were formulated to contain different Fe levels (0, 43.1, 84.2, 123.3, 162.2 and 203.1 mg/kg of dry diet) using ferrous sulphate (FeSO4) as the source. The weight gain (WG) and the specific growth ratio (SGR) of A. nobilis fed with a dietary Fe level of 123.3 mg/kg were significantly higher than that of the 0 mg/kg Fe group (p < .05). The results indicated that the growth was affected by dietary Fe levels. Regression analysis of WG and SGR at different levels of dietary Fe suggests that the appropriate dietary requirement of Fe for the bighead carp larvae is 120–134.36 mg/kg. The Fe contents in different tissues were as follows: spleen > liver > whole body. When the Fe dietary content increases to 162.2 mg/kg, the blood concentrations of Fe significantly decreased and thereafter increased, hepcidin significantly decreased and thereafter decreased, and transferrin significantly increased and thereafter decreased. The results indicate that the transferrin blood content significantly increased with decreasing hepcidin of up to 264.63 μg/ml content and thereafter decreased. It could be concluded that after transferrin saturation, hepcidin functions to maintain iron balance in the blood of A. nobilis by decreasing transferrin content.  相似文献   

19.
A physiological study was performed to explore the effects in Sphoeroides annulatus (Jenyns 1842) juveniles of exposure to different salinities 10, 17, 23, 29, 35 and 41‰ on oxygen consumption rate (OCR), ammonium excretion rate (AER), the oxygen‐nitrogen atomic ratio (O:N), osmoregulation and Na+/K+‐ATPase expression. The OCR values ranged from 27.9 to 30.9 mg O2 h?1 kg?1, displaying a Type 1 response pattern Kinne (1977). AER ranged from 0.60 to 0.69 mg h?1 kg?1, and O:N values were from 53.12 to 59.26, indicating that the puffers use proteins and lipids as an energy‐substrate. Osmoregulation in S. annulatus was hyposmotic in salinities of 23, 29, 35 and 41‰ and hyperosmotic in a salinity of 10‰. The isosmotic point of the bullseye puffer was 356 mmol kg?1 (10.5‰). The enzyme expression analysis indicates that the fish acclimated to 41‰ had the highest Na+/K+‐ATPase expression level, whereas, the lowest expression level was found close to the isosmotic point. Na+/K+‐ATPase expression in the gills was found to have a U‐shaped relationship with environmental salinity. We conclude that the bullseye puffer is strongly euryhaline and can be cultivated in a wide range of environments that has important economic implications.  相似文献   

20.
微卫星分离模式显示雄性三倍体鲫产生非整倍体精子   总被引：1，自引：1，他引：0  
三倍体鲫(Carassius auratus)行天然雌核发育,其自然种群中却有较高比例的雄性个体,这些雄性个体的性腺发育正常,能产生有活力的精子。而且其精子的DNA含量约为体细胞的一半,显示三倍体鲫精子发生过程中可能经历了均等的减数分裂。流式细胞术虽然能够较准确地测定细胞群的平均DNA含量,但是却很难检测到单个精子中的个别染色体增减,要明确回答雄性三倍体鲫产生的精子是否为整倍体需要定量地检测单个精子的遗传组成。本研究用微卫星标记检测以雌性鲤(Cyprinus carpio)与雄性三倍体鲫为亲本构建的杂种家系的基因型,结果发现母本鲤的多态位点在子代中呈孟德尔分离,父本三倍体鲫具有三套鲫基因组,其等位基因在子代中呈随机分离。上述研究结果提示:三倍体鲫起源于二倍体鲫的同源加倍,而非二倍体鲫和鲤的种间杂交;三倍体鲫通过染色体的随机分离产生非整倍体的精子,其精子发生过程中没有均等的减数分裂。三倍体鲫行雌核发育生殖,却可能并非起源于种间杂交且群体中的雄性个体可育,因而是单性生殖鱼类中的一个特例。  相似文献   

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