为比较星洲红鱼(Singapore red tilapia)和奥尼罗非鱼(Oreochromis niloticus)的生长和肌肉营养特性,实验利用两种鱼的不同体色将其混养在同一池塘中,在相同的环境条件和养殖管理下研究其生长特性,并分析肌肉营养成分。结果表明:两种罗...为比较星洲红鱼(Singapore red tilapia)和奥尼罗非鱼(Oreochromis niloticus)的生长和肌肉营养特性,实验利用两种鱼的不同体色将其混养在同一池塘中,在相同的环境条件和养殖管理下研究其生长特性,并分析肌肉营养成分。结果表明:两种罗非鱼生长在前60 d无差异,60 d后星洲红鱼的体长、体质量日增长和特定生长率均大于奥尼罗非鱼,且差异显著(P<0.05)。据此得到了星洲红鱼和奥尼罗非鱼的体长(L)、体质量(W)生长与养殖天数(d)的回归方程。星洲红鱼含肉率高于奥尼罗非鱼9.65%(P<0.05),肌肉水分高于奥尼罗非鱼,蛋白质、粗脂肪和灰分含量均低于奥尼罗非鱼,其中脂肪含量差异显著(P<0.05),其他不显著。两种罗非鱼肌肉的氨基酸组成全面,氨基酸组成均符合FAO/WHO的理想模式,除精氨酸含量有差异外,其他氨基酸含量稍有差异但不显著。星洲红鱼和奥尼罗非鱼肌肉EAA/TAA、EAA/NEAA、DAA/TAA和EAAI分别为41.04%和40.95%,70.00%和69.34%,40.71%和39.08%,67.46%和67.08%,差异不显著。星洲红鱼、奥尼罗非鱼肌肉∑SFA和∑UFA分别为28.03%和28.60%,63.87%和61.38%,各脂肪酸含量除C14:0和C18:2外,其他含量差异不显著。研究表明,星洲红鱼和奥尼罗非鱼生长快、营养丰富、食用价值高,是优质淡水鱼类养殖品种,其中星洲红鱼含肉率高,生长快,养殖效益明显。展开更多
The effects of phenanthrene(Phe) on hepatosomatic index(HSI) and hepatic enzymatic activities in hybrid tilapia(Oreochromis niloticus ♀× O.aureus ♂) were investigated via the static freshwater exposure at...The effects of phenanthrene(Phe) on hepatosomatic index(HSI) and hepatic enzymatic activities in hybrid tilapia(Oreochromis niloticus ♀× O.aureus ♂) were investigated via the static freshwater exposure at dosage of 50,100,and 400 μg/L for 4-14 d.Compared with the control group,HSI was significantly decreased(P 〈 0.05) at 400 μg/L at day 14.Increased enzymatic activities(P 〈 0.05) were observed for catalase(CAT),glutathione peroxidase(GPx) and superoxide dismutase(SOD) at either 100 or 400 μg/L at day 8 and 14,as well as for CAT at 50 μg/L at day 14,except for GPx at 400 μg/L at day 8.Ethoxyresorufin O-deethylase(EROD) activity was significantly increased(P 〈 0.05) at all dosage at day 4 as well as at 50 μg/L at day 8,but significantly decreased at either 100 or 400 μg/L at day 14(P 〈 0.05).Glutathione-S-transferase(GST) activity was not affected.The results suggest that CAT,GPx,SOD and EROD,as well as HSI in tilapia may be used as the biomarkers or indexes for evaluating or monitoring the pollution of polycyclic aromatic hydrocarbons(PAHs) such as Phe.展开更多
The efficacy of Endocrine Disrupting Compounds (EDCs), 17β-estradiol was tested on the fish Oreochromis niloticus in order to understand the intersex relationship of fish, in which sequential hermaphrodism can consis...The efficacy of Endocrine Disrupting Compounds (EDCs), 17β-estradiol was tested on the fish Oreochromis niloticus in order to understand the intersex relationship of fish, in which sequential hermaphrodism can consist of a male changing into a female (protandry) or a female changing into a male (protogyny). The fish were equally divided into 3 groups. The first group was the control group;the second and third groups were treated with 10 and 100 mg L-1 of 17β-estradiol, respectively, for 30 days. The overall result in this experiment had no significant effect on the growth parameters. Among the two treated groups, the low concentration group shows results similar to those of the control groups. The high concentration group shows changes to the male reproductive system with the appearance of the testis-ova present resulting in an intersex condition of the male gonads. With this experiment, it can be concluded that 17β-estradiol at high concentration reveals positive changes towards the male reproductive system of the fish, Oreochromis niloticus.展开更多
Shelf-life extension of aquatic products is of significant economical importance. To determine the potential effect of chitosan on the shelf-life of filleted tilapia, this study analyzed the bacterial community divers...Shelf-life extension of aquatic products is of significant economical importance. To determine the potential effect of chitosan on the shelf-life of filleted tilapia, this study analyzed the bacterial community diversity in fresh and spoiled tilapia fillets stored at (4 ± 1)℃ and examined the antimicrobial activity of chitosan against relevant bacteria isolates. Results showed that Pseudomonas (20%) and Aeromonas (16%) were abundant in fresh tilapia fillets, whereas Pseudomonas (52%), Aeromonas (32%) and Staphylococcus (12%) were dominant in the spoiled samples. Chitosan showed wide-spectrum antibacterial activity against bacteria isolated from tilapia and 5.0 g L-1 chitosan was selected for application in preservation. We further determined the shelf-life of chitosan-treated, filleted tilapia stored at (4 ± 1)℃ based on microbiological, biochemical and sensory analyses. Results showed that the shelf-life of chitosan-treated, filleted tilapia was extended to 12 d, whereas that of untreated, control samples was 6 d. These indicate that chitosan, as a natural preservative, has great application potential in the shelf-life extension of tilapia fillets.展开更多
The juveniles of hybrid tilapia ( Oreochromis niloticus x Oreochromis areus) were exposed to ananonia-nitrogen (N) (0, 2.5, 5, 10 and 20 mg/L) for 0, 12, 24, 48 and 72 h to evaluate the effect of ammonia-N stres...The juveniles of hybrid tilapia ( Oreochromis niloticus x Oreochromis areus) were exposed to ananonia-nitrogen (N) (0, 2.5, 5, 10 and 20 mg/L) for 0, 12, 24, 48 and 72 h to evaluate the effect of ammonia-N stress on their non-specific immunity. Results show that the activity of serum lysozyme decreased signifi- candy with extension of stress time (P 〈 0.05). The total antioxidant capacity (T-AOC) and activity of antioxidase in liver were significantly affected. The activi- ty of T-AOC and total superoxide dismutase (T-SOD) of fish exposed to ammonia-N were initially decreasing then increasing ( P 〈 0.05 ). Activities of catalase (CAT) and glutathione peroxidase (GSH-Px) were correlated with concentrations of ammonia-N. Fish exposed to lower concentrations (2.5 mg/L or 5 mg/L) showed decreased CAT activity within 24 h (P 〈 0.05 ), while those exposed to higher concentrations (10 mg/L or 20 mg/L) initially showed increased then decreased activity of CAT. Except for the highest concentration groups, fish exposed to ammonia-N showed inductive activity of GSH-Px ( P 〈 0.05 ). Under the ex- perimental conditions, non-specific immunity of tilapia was affected by ammonia-N stress, and the impact was increased with increased concentration and extension of time.展开更多
Nitrogen (N) and phosphorus (P) wastes produced by Nile tilapia Oreochromis niloticus L. fed Azolla, an aquatic atmospheric nitrogen fixing fern, was evaluated for 90 days in pond experiment. Six isonitrogenous (29.2%...Nitrogen (N) and phosphorus (P) wastes produced by Nile tilapia Oreochromis niloticus L. fed Azolla, an aquatic atmospheric nitrogen fixing fern, was evaluated for 90 days in pond experiment. Six isonitrogenous (29.2% crude protein) and isoenergetic (16.9 Kj·g–1) diets A0, A10, A20, A30, A40 and A50, containing 0%, 10%, 20%, 30%, 40% and 50% of Azolla meal (AM) respectively, as partial fishmeal (FM) substitutes, was provided to experimental fish. The Azolla-free diet A0 served as a control. Fish specific growth rate (SGR) was higher with the control diet, the lower values being obtained in A50-fed fish (P Azolla could be used in diet to sustain Nile tilapia growth and as “environmentally-friendly” ingredient to limit P loss, while providing N to the field, beneficially in tropical marshland pond where this nutrient is already limiting.展开更多
Native polyacrylamide gel electrophoresis have been used to analyze malate dehydrogenase (MDH), acid phosphatase (Acph) and peroxidase (Px) isoenzymes in different tissues (liver, kidney, muscle and heart) of the tila...Native polyacrylamide gel electrophoresis have been used to analyze malate dehydrogenase (MDH), acid phosphatase (Acph) and peroxidase (Px) isoenzymes in different tissues (liver, kidney, muscle and heart) of the tilapia fish, Oreo- chromis niloticus in order to study the tissue specificity of these isoenzymes. Three, two and one fractions have been recorded respectively for the three isoenzymes in different studied tissues. The MDH-1 and MDH-2 have been ex- pressed only in muscle and heart while MDH-3 has been expressed in all studied tissues. The percentage amount of MDH in general varied significantly between muscle and different studied tissues. With respect to acid phosphatase, the percentage amount of the total enzyme showed significant difference between liver and muscle and that this variation may be due to higher gene activity in liver. Peroxidase isoenzyme was recorded in liver and heart only with significant increase in liver. The kidney was the least among the studied tissues in showing gene expression for the studied isoenzymes and therefore, liver, heart and muscle tissues are better applicable in studying the isoenzymatic profiles for fish physiology and systematics.展开更多
Successful crossbreeding between Oreochromis niloticus and Sarotherodon melanotheron to produce a commercial hybrid has been difficult.The karyotypes and isoenzyme of these two species and their reciprocal hybrids(O....Successful crossbreeding between Oreochromis niloticus and Sarotherodon melanotheron to produce a commercial hybrid has been difficult.The karyotypes and isoenzyme of these two species and their reciprocal hybrids(O.niloticus ♀ × S.melanotheron ♂,S.melanotheron ♀ × O.niloticus ♂,the last not included in the isoenzyme study) were investigated via metaphase chromosomes obtained from head kidney cells and electropherogram of lactate dehydrogenase(LDH) isoenzymes from the liver,kidney,white muscle,heart,and eye balls.The diploid chromosome number(2n=44) and the fundamental number(NF=50) of the four tilapia genotypes were the same.However,the karyotype of O.niloticus had three pairs of sub-metacentric(sm),twelve pairs of sub-telocentric(st),and seven pairs of telocentric(t) chromosomes,while S.melanotheron had one pair of metacentric(m),two pairs of sm,12 pairs of st,and seven pairs of t chromosomes.The reciprocal hybrids both showed a mixed karyotype range between their parents:0.5 pair of m,2.5 pairs of sm,12 pairs of st,and seven pairs of t chromosomes.In view of the electropherogram of isozymes,only the LDH of the kidney showed significant clear bands,with five bands in O.niloticus,three bands in S.melanotheron,and duplicated six bands in the hybrids.The bands varied depending on their activities and mobilities.We considered that the differences in karyotype and isoenzyme were related to the genetic mechanism for post-mating isolation,and provided some additional basic genetic background of their taxonomy.展开更多
性类固醇激素对动物生长有一定的影响,但其对鱼类雌、雄生长差异的影响机理尚不清楚。为进一步了解动物雌雄生长差异的内在原因,本文通过在体注射和荧光定量PCR方法,比较了性类固醇激素(E_2、MT)对尼罗罗非鱼雌鱼和雄鱼的生长及对垂体G...性类固醇激素对动物生长有一定的影响,但其对鱼类雌、雄生长差异的影响机理尚不清楚。为进一步了解动物雌雄生长差异的内在原因,本文通过在体注射和荧光定量PCR方法,比较了性类固醇激素(E_2、MT)对尼罗罗非鱼雌鱼和雄鱼的生长及对垂体GH、肝脏GHR1、IGF-I m RNA表达的影响。结果表明:性类固醇激素E2和MT对尼罗罗非鱼的生长及生长轴相关基因的表达均有显著的影响,并且这种影响存在明显的性别二态性。E_2明显促进雌鱼的生长但不显著影响雄鱼的生长,MT显著促进雄鱼和雌鱼的生长;E2可使雌鱼垂体GH和肝脏GHR1、IGF-I的m RNA水平显著升高(P<0.05),但降低雄鱼垂体GH和肝脏GHR1的m RNA表达;MT显著提高雄鱼垂体GH和肝脏GHR1、IGF-I m RNA水平(P<0.05),但降低雌鱼垂体GH的m RNA表达,促进雌鱼肝脏GHR1 m RNA的表达,但对雄鱼肝脏GHR1的促进作用明显大于雌鱼(P<0.05)。上述结果表明,性类固醇激素对不同性别尼罗罗非鱼的生长及生长轴相关基因的m RNA表达有不同的影响,表现出明显的性别二态性,提示不同性别鱼体内性类固醇激素水平的不同可能是导致尼罗罗非鱼雌雄生长二态性的另一内在原因。展开更多
Through PCR amplification, 5’ flanking region and partial open reading frame(ORF) of gene of Nile tilapia(Oreochromis niloticus) was cloned by PCR amplification. Sequence analysis showed that no difference was fo...Through PCR amplification, 5’ flanking region and partial open reading frame(ORF) of gene of Nile tilapia(Oreochromis niloticus) was cloned by PCR amplification. Sequence analysis showed that no difference was found in known functional regions. This study was to construct and identify the mammalian expression vector of pEGFP-β-actin and to detect whether it could express in HEK 293T cell line. pEGFP-β-actin was transfected into HEK 293T cells with Lipofectamine 2000. The results showed that correct construction of recombinant pEGFP-β-actin has been shown by restriction enzyme digestion. The expression of gene in HEK 293T cells could be observed under microfluoroscope. pEGFP-β-actin could repress EGFP protein in HEK 293T cells. The results showed that β-actin gene promoter possessed effective transcription activities in eukaryotic cells. The work laid foundations for further study on the gene engineering and autotransgenic tilapia.展开更多
Since amateur fishing in fishponds has been on the increase in Brazil, there is a great concern on the microbiological quality of fish. One hundred and thirty-eight samples were collected during the dry and rainy peri...Since amateur fishing in fishponds has been on the increase in Brazil, there is a great concern on the microbiological quality of fish. One hundred and thirty-eight samples were collected during the dry and rainy periods in ten fish farms. Aeromonas spp. counts and tests for sensitiveness to antimicrobials were performed, coupled to the physical and chemical analyses of water. Tests revealed that 70% of samples were contaminated by Aeromonas spp., with water averaging 2.92 Log CFU/100 mL during the rainy period and 3.16 Log CFU/100 mL during the dry one. Fish contaminated by Aeromonas spp. averaged 2.58 Log CFU/100 mL during the rainy period and 3.53 Log CFU/100 mL during the dry one. Aeromonas spp. samples were multi-resistant to 2 or 8 antimicrobials in 62.5% of the samples. Ampicillin was the antimicrobial with the highest resistance percentage rate. Results showed that fish bred in amateur fish farms constituted a health risk for the population.展开更多
The approximate general composition and the fatty acid profile of Nile tilapia fed Azolla-diets in ponds were studied for 90 days. Six isonitrogenous (29.2% CP) and isoenergetic (16.9 kJ·g>sup>-1) diets wer...The approximate general composition and the fatty acid profile of Nile tilapia fed Azolla-diets in ponds were studied for 90 days. Six isonitrogenous (29.2% CP) and isoenergetic (16.9 kJ·g>sup>-1) diets were formulated to contain 0% (A0), 10% (A10), 20% (A>sub>20), 30% (A30), 40% (A40) and 50% (A50) of Azolla meal (AM), as partial fish meal (FM) substitutes. Diet A0 without AM served as a control. Fish growth decreased as AM level exceeded 20% in diets (P 0.05). Crude lipid was significantly lower in fish fed A50 and significant differences were also found in crude ash (P 20, A30 and A50. High level of the fern reduces growth without negatively affecting fatty acid in fish. Fish PUFA, especially the (n - 3) fatty acids, are affected positively, even when fed 50% AM, which is good for the quality of the fish produced in regard to the benefits for the health of consumers.展开更多
基金supported by the National Natural Science Foundation of China (No. 30570325,30671629)the Science and Technology Project of Guangdong Province (No.2005B20301013, 2006A36502004,2007B090400049)
文摘The effects of phenanthrene(Phe) on hepatosomatic index(HSI) and hepatic enzymatic activities in hybrid tilapia(Oreochromis niloticus ♀× O.aureus ♂) were investigated via the static freshwater exposure at dosage of 50,100,and 400 μg/L for 4-14 d.Compared with the control group,HSI was significantly decreased(P 〈 0.05) at 400 μg/L at day 14.Increased enzymatic activities(P 〈 0.05) were observed for catalase(CAT),glutathione peroxidase(GPx) and superoxide dismutase(SOD) at either 100 or 400 μg/L at day 8 and 14,as well as for CAT at 50 μg/L at day 14,except for GPx at 400 μg/L at day 8.Ethoxyresorufin O-deethylase(EROD) activity was significantly increased(P 〈 0.05) at all dosage at day 4 as well as at 50 μg/L at day 8,but significantly decreased at either 100 or 400 μg/L at day 14(P 〈 0.05).Glutathione-S-transferase(GST) activity was not affected.The results suggest that CAT,GPx,SOD and EROD,as well as HSI in tilapia may be used as the biomarkers or indexes for evaluating or monitoring the pollution of polycyclic aromatic hydrocarbons(PAHs) such as Phe.
文摘The efficacy of Endocrine Disrupting Compounds (EDCs), 17β-estradiol was tested on the fish Oreochromis niloticus in order to understand the intersex relationship of fish, in which sequential hermaphrodism can consist of a male changing into a female (protandry) or a female changing into a male (protogyny). The fish were equally divided into 3 groups. The first group was the control group;the second and third groups were treated with 10 and 100 mg L-1 of 17β-estradiol, respectively, for 30 days. The overall result in this experiment had no significant effect on the growth parameters. Among the two treated groups, the low concentration group shows results similar to those of the control groups. The high concentration group shows changes to the male reproductive system with the appearance of the testis-ova present resulting in an intersex condition of the male gonads. With this experiment, it can be concluded that 17β-estradiol at high concentration reveals positive changes towards the male reproductive system of the fish, Oreochromis niloticus.
基金supported by the Special Funds for the Basic Research and Development Program in the Central Non-profit Research Institutes of China (No.20603022011005)
文摘Shelf-life extension of aquatic products is of significant economical importance. To determine the potential effect of chitosan on the shelf-life of filleted tilapia, this study analyzed the bacterial community diversity in fresh and spoiled tilapia fillets stored at (4 ± 1)℃ and examined the antimicrobial activity of chitosan against relevant bacteria isolates. Results showed that Pseudomonas (20%) and Aeromonas (16%) were abundant in fresh tilapia fillets, whereas Pseudomonas (52%), Aeromonas (32%) and Staphylococcus (12%) were dominant in the spoiled samples. Chitosan showed wide-spectrum antibacterial activity against bacteria isolated from tilapia and 5.0 g L-1 chitosan was selected for application in preservation. We further determined the shelf-life of chitosan-treated, filleted tilapia stored at (4 ± 1)℃ based on microbiological, biochemical and sensory analyses. Results showed that the shelf-life of chitosan-treated, filleted tilapia was extended to 12 d, whereas that of untreated, control samples was 6 d. These indicate that chitosan, as a natural preservative, has great application potential in the shelf-life extension of tilapia fillets.
基金Supported by Guangdong Natural Science Foundation(S2013010013693,S2011010003451)Science and Technology Project of Guangdong Province(2013B020307016)Excellent Young Teachers Program of Guangdong(Yq2013152)
文摘The juveniles of hybrid tilapia ( Oreochromis niloticus x Oreochromis areus) were exposed to ananonia-nitrogen (N) (0, 2.5, 5, 10 and 20 mg/L) for 0, 12, 24, 48 and 72 h to evaluate the effect of ammonia-N stress on their non-specific immunity. Results show that the activity of serum lysozyme decreased signifi- candy with extension of stress time (P 〈 0.05). The total antioxidant capacity (T-AOC) and activity of antioxidase in liver were significantly affected. The activi- ty of T-AOC and total superoxide dismutase (T-SOD) of fish exposed to ammonia-N were initially decreasing then increasing ( P 〈 0.05 ). Activities of catalase (CAT) and glutathione peroxidase (GSH-Px) were correlated with concentrations of ammonia-N. Fish exposed to lower concentrations (2.5 mg/L or 5 mg/L) showed decreased CAT activity within 24 h (P 〈 0.05 ), while those exposed to higher concentrations (10 mg/L or 20 mg/L) initially showed increased then decreased activity of CAT. Except for the highest concentration groups, fish exposed to ammonia-N showed inductive activity of GSH-Px ( P 〈 0.05 ). Under the ex- perimental conditions, non-specific immunity of tilapia was affected by ammonia-N stress, and the impact was increased with increased concentration and extension of time.
文摘Nitrogen (N) and phosphorus (P) wastes produced by Nile tilapia Oreochromis niloticus L. fed Azolla, an aquatic atmospheric nitrogen fixing fern, was evaluated for 90 days in pond experiment. Six isonitrogenous (29.2% crude protein) and isoenergetic (16.9 Kj·g–1) diets A0, A10, A20, A30, A40 and A50, containing 0%, 10%, 20%, 30%, 40% and 50% of Azolla meal (AM) respectively, as partial fishmeal (FM) substitutes, was provided to experimental fish. The Azolla-free diet A0 served as a control. Fish specific growth rate (SGR) was higher with the control diet, the lower values being obtained in A50-fed fish (P Azolla could be used in diet to sustain Nile tilapia growth and as “environmentally-friendly” ingredient to limit P loss, while providing N to the field, beneficially in tropical marshland pond where this nutrient is already limiting.
文摘Native polyacrylamide gel electrophoresis have been used to analyze malate dehydrogenase (MDH), acid phosphatase (Acph) and peroxidase (Px) isoenzymes in different tissues (liver, kidney, muscle and heart) of the tilapia fish, Oreo- chromis niloticus in order to study the tissue specificity of these isoenzymes. Three, two and one fractions have been recorded respectively for the three isoenzymes in different studied tissues. The MDH-1 and MDH-2 have been ex- pressed only in muscle and heart while MDH-3 has been expressed in all studied tissues. The percentage amount of MDH in general varied significantly between muscle and different studied tissues. With respect to acid phosphatase, the percentage amount of the total enzyme showed significant difference between liver and muscle and that this variation may be due to higher gene activity in liver. Peroxidase isoenzyme was recorded in liver and heart only with significant increase in liver. The kidney was the least among the studied tissues in showing gene expression for the studied isoenzymes and therefore, liver, heart and muscle tissues are better applicable in studying the isoenzymatic profiles for fish physiology and systematics.
文摘Successful crossbreeding between Oreochromis niloticus and Sarotherodon melanotheron to produce a commercial hybrid has been difficult.The karyotypes and isoenzyme of these two species and their reciprocal hybrids(O.niloticus ♀ × S.melanotheron ♂,S.melanotheron ♀ × O.niloticus ♂,the last not included in the isoenzyme study) were investigated via metaphase chromosomes obtained from head kidney cells and electropherogram of lactate dehydrogenase(LDH) isoenzymes from the liver,kidney,white muscle,heart,and eye balls.The diploid chromosome number(2n=44) and the fundamental number(NF=50) of the four tilapia genotypes were the same.However,the karyotype of O.niloticus had three pairs of sub-metacentric(sm),twelve pairs of sub-telocentric(st),and seven pairs of telocentric(t) chromosomes,while S.melanotheron had one pair of metacentric(m),two pairs of sm,12 pairs of st,and seven pairs of t chromosomes.The reciprocal hybrids both showed a mixed karyotype range between their parents:0.5 pair of m,2.5 pairs of sm,12 pairs of st,and seven pairs of t chromosomes.In view of the electropherogram of isozymes,only the LDH of the kidney showed significant clear bands,with five bands in O.niloticus,three bands in S.melanotheron,and duplicated six bands in the hybrids.The bands varied depending on their activities and mobilities.We considered that the differences in karyotype and isoenzyme were related to the genetic mechanism for post-mating isolation,and provided some additional basic genetic background of their taxonomy.
文摘性类固醇激素对动物生长有一定的影响,但其对鱼类雌、雄生长差异的影响机理尚不清楚。为进一步了解动物雌雄生长差异的内在原因,本文通过在体注射和荧光定量PCR方法,比较了性类固醇激素(E_2、MT)对尼罗罗非鱼雌鱼和雄鱼的生长及对垂体GH、肝脏GHR1、IGF-I m RNA表达的影响。结果表明:性类固醇激素E2和MT对尼罗罗非鱼的生长及生长轴相关基因的表达均有显著的影响,并且这种影响存在明显的性别二态性。E_2明显促进雌鱼的生长但不显著影响雄鱼的生长,MT显著促进雄鱼和雌鱼的生长;E2可使雌鱼垂体GH和肝脏GHR1、IGF-I的m RNA水平显著升高(P<0.05),但降低雄鱼垂体GH和肝脏GHR1的m RNA表达;MT显著提高雄鱼垂体GH和肝脏GHR1、IGF-I m RNA水平(P<0.05),但降低雌鱼垂体GH的m RNA表达,促进雌鱼肝脏GHR1 m RNA的表达,但对雄鱼肝脏GHR1的促进作用明显大于雌鱼(P<0.05)。上述结果表明,性类固醇激素对不同性别尼罗罗非鱼的生长及生长轴相关基因的m RNA表达有不同的影响,表现出明显的性别二态性,提示不同性别鱼体内性类固醇激素水平的不同可能是导致尼罗罗非鱼雌雄生长二态性的另一内在原因。
基金Supported by China Agriculture Research System(CARS-49)Fujian Seed Industry Innovation and Industrialization(2011FJZY)
文摘Through PCR amplification, 5’ flanking region and partial open reading frame(ORF) of gene of Nile tilapia(Oreochromis niloticus) was cloned by PCR amplification. Sequence analysis showed that no difference was found in known functional regions. This study was to construct and identify the mammalian expression vector of pEGFP-β-actin and to detect whether it could express in HEK 293T cell line. pEGFP-β-actin was transfected into HEK 293T cells with Lipofectamine 2000. The results showed that correct construction of recombinant pEGFP-β-actin has been shown by restriction enzyme digestion. The expression of gene in HEK 293T cells could be observed under microfluoroscope. pEGFP-β-actin could repress EGFP protein in HEK 293T cells. The results showed that β-actin gene promoter possessed effective transcription activities in eukaryotic cells. The work laid foundations for further study on the gene engineering and autotransgenic tilapia.
基金thank CAPES for the award of scholarship to the auhor
文摘Since amateur fishing in fishponds has been on the increase in Brazil, there is a great concern on the microbiological quality of fish. One hundred and thirty-eight samples were collected during the dry and rainy periods in ten fish farms. Aeromonas spp. counts and tests for sensitiveness to antimicrobials were performed, coupled to the physical and chemical analyses of water. Tests revealed that 70% of samples were contaminated by Aeromonas spp., with water averaging 2.92 Log CFU/100 mL during the rainy period and 3.16 Log CFU/100 mL during the dry one. Fish contaminated by Aeromonas spp. averaged 2.58 Log CFU/100 mL during the rainy period and 3.53 Log CFU/100 mL during the dry one. Aeromonas spp. samples were multi-resistant to 2 or 8 antimicrobials in 62.5% of the samples. Ampicillin was the antimicrobial with the highest resistance percentage rate. Results showed that fish bred in amateur fish farms constituted a health risk for the population.
文摘The approximate general composition and the fatty acid profile of Nile tilapia fed Azolla-diets in ponds were studied for 90 days. Six isonitrogenous (29.2% CP) and isoenergetic (16.9 kJ·g>sup>-1) diets were formulated to contain 0% (A0), 10% (A10), 20% (A>sub>20), 30% (A30), 40% (A40) and 50% (A50) of Azolla meal (AM), as partial fish meal (FM) substitutes. Diet A0 without AM served as a control. Fish growth decreased as AM level exceeded 20% in diets (P 0.05). Crude lipid was significantly lower in fish fed A50 and significant differences were also found in crude ash (P 20, A30 and A50. High level of the fern reduces growth without negatively affecting fatty acid in fish. Fish PUFA, especially the (n - 3) fatty acids, are affected positively, even when fed 50% AM, which is good for the quality of the fish produced in regard to the benefits for the health of consumers.