The aim of the present study is to detect the potential of the base population from diallel crosses of eight introduced strains of the Pacific white shrimp(Litopenaeus vannamei) for improving the yield. Heterosis an...The aim of the present study is to detect the potential of the base population from diallel crosses of eight introduced strains of the Pacific white shrimp(Litopenaeus vannamei) for improving the yield. Heterosis and heritability were estimated for pond survival at commercial farm conditions for the base population that included 207 full-sib families from a nested mating design by artificial insemination. Among all the hybrids,the heterosis ranged from –11.37%(UA1×UA2) to 20.53%(UA3×SIN) with an average of 0.953%. The results showed that more than half of the hybrids(51.85%) have negative heterosis for survival rate, but most of the hybrids with positive heterosis have high estimates. The high proportion of negative heterosis for survival rate reminders us that the survival trait also should be considered in the crossbreeding program to avoid yield decrease. However, high positive heterosis manifested in most of the hybrids for survival indicates the usefulness of these hybrids for improving the survival to obtain higher yield by crossbreeding in this breeding program. The heritability estimate for pond survival was 0.092±0.043 when genetic groups were included in the pedigree, and it was significantly different from zero(P〈0.05). The results from this study also indicated that significant improvement for survival is possible through selection in L. vannamei.展开更多
A six-week growth trial was conducted to compare the effects of different feeding strate- gies of dietary immunostimulants on the growth and immunity of white shrimp Litopenaeus vannamei (4.70 ±0.20g). Shrimps ...A six-week growth trial was conducted to compare the effects of different feeding strate- gies of dietary immunostimulants on the growth and immunity of white shrimp Litopenaeus vannamei (4.70 ±0.20g). Shrimps were fed with diet containing glycyrrhizin continuously, containing β -glucan continuously, discontinuously (seven days with diet containing β -gluseven days with diet without -glucan; two days with diet containing β-glucan following five days with diet without -glucan),展开更多
The optimal quantity of dietary lysine (Lys) and arginine (Arg), and the optimal ratio of dietary Lys to Arg for Pacific white shrimp Litopenaeus vannamei were investigated. Coated Lys and Arg were added to a basal di...The optimal quantity of dietary lysine (Lys) and arginine (Arg), and the optimal ratio of dietary Lys to Arg for Pacific white shrimp Litopenaeus vannamei were investigated. Coated Lys and Arg were added to a basal diet (37.99% crude protein and 7.28% crude lipid) to provide graded levels of Lys and Arg. The experimental diets contained three Lys levels (2.51%, 2.11%, and 1.70% of total diet), and three Arg levels (1.41%, 1.80%, and 2.21% of total diet) and all combinations of these levels were tested. Pacific white shrimp, with a mean weight of 3.62±0.1 g, were randomly distributed in 36 fiberglass tanks with 30 shrimp per tank and reared on the experimental diets for 50 days. After the feeding trial, the growth performance, survival, feed conversion rate (FCR), body composition and protease and lipase activities in the hepatopancreases of the experimental shrimps were determined. The results show that weight gain (WG), specific growth rate (SGR), FCR, body protein, body Lys and Arg content were significantly affected by dietary Lys and Arg (P<0.05) and improved when dietary Lys and Arg levels were 2.11% 2.51% and 1.80% 2.21%, respectively. Protease and lipase activities in the hepatopancreases of the shrimps appeared higher when dietary Lys and Arg quantities were 2.11% 2.51% and 1.80% 2.21%, although the difference was not statistically significant (P>0.05). Therefore, according to our results, the optimal Lys and Arg quantities in the diet of Pacific white shrimp, L. vannamei, were considered to be 2.11%-2.51% and 1.80%- 2.21%, respectively, and the optimal ratio to be 1:0.88-1:1.05.展开更多
Seven growth-related traits were measured to assess the selection response and genetic parameters of the growth of Pacific white shrimp, Litopenaeus vannamei, which had been domesticated in tanks for more than four ge...Seven growth-related traits were measured to assess the selection response and genetic parameters of the growth of Pacific white shrimp, Litopenaeus vannamei, which had been domesticated in tanks for more than four generations. Phenotypic and genetic parameters were evaluated and fitted to an animal model. Realized response was measured from the difference between the mean growth rates of selected and control families. Realized heritability was determined from the ratio of the selection responses and selection differentials. The animal model heritability estimate over generations was 0.44±0.09 for body weight (BW), and ranged from 0.21±0.08 to 0.37±0.06 for size traits. Genetic correlations of phenotypic traits were more variable (0.51-0.97), although correlations among various traits were high (>0.83). Across generations, BW and size traits increased, while selection response and heritability gradually decreased. Selection responses were 12.28%-23.35% for harvest weight and 3.58%-13.53% for size traits. Heritability estimates ranged from 0.34±0.09 to 0.48±0.15 for harvest weight and 0.17±0.01-0.38±0.11 for size traits. All phenotypic and genetic parameters differed between various treatments. To conclude, the results demonstrated a potential for mass selection of growth traits in L. vannamei. A breeding scheme could use this information to integrate the effectiveness constituent traits into an index to achieve genetic progress.展开更多
Microfungi have been explored further as supplement constituents in shrimp culture due to their rich protein,lipid,essential amino acids,fatty acids,and various bioactive compounds.The researchers have evaluated the e...Microfungi have been explored further as supplement constituents in shrimp culture due to their rich protein,lipid,essential amino acids,fatty acids,and various bioactive compounds.The researchers have evaluated the effects of two microfungi powders(Mucor circinelloides and Trichoderma harzianum)as feed supplements on growth performance,bacterial communities,and the biomass nutritional profile of white shrimp(Litopenaeus vannamei).The results showed that commercial/artificial feed(Feng-Li)with supplementation microfungi powder had a different effect on white shrimp growth performance than control after 62 days of the grow-out period.Supplementation with 1.5%M.circinelloides powder(M-2)could improve the growth performance of white shrimp,especially the survival rate(81.33%),final body weight(5.21 g),and shrimp biomass(211.35 g).In contrast,supplementation with 1.5%T.harzianum powder(T-2)did not improve the growth performance of white shrimp compared to control(p>0.05).Furthermore,it also affected the profile of the bacterial community in culture water as well as in shrimp intestines.Supplementation with both microfungi could reduce the total number of bacteria in culture water at the end of the experiment,where the lowest number was obtained in treatment T-2(3.9×10^(5)CFU/mL),followed by M-2(9.9×10^(5)CFU/mL)and control(4.4×10^(6)CFU/mL).In the culture water,20 isolates of culturable bacteria were found during the trial,with the dominant bacteria in M-2:Bacillus cereus,Bacillus velezensis,Gordonia polyisoprenivorans,T-2:Acinetobacter sp.,Gordonia polyisoprenivorans,Micrococcus luteus.Based on average well colour development(AWCD),the highest bacterial activity was in the M-2(0.297-0.707),followed by T-2(0.226-0.717)and control(0.094-0.694).The highest substrate group utilised in M-2 and T-2 were polymers(0.896 and 1.348)and control:amines(0.100).The highest Shannon diversity index was obtained in the M-2(2.508),followed by control(2.286)and the T-2(2.157).As many as 11 isolates of culturable bacteria were found in the shrimp intestine,with dominant bacteria in M-2:Bacillus velezensis,Micrococcus luteus,Bacillus cereus,T-2:Bacillus velezensis,Micrococcus sp.2,Demequina activiva.The highest bacterial activity was in M-2(2.259),followed by control(2.020)and T-2(0.050).The highest substrate group utilisation was in M-2:polymers(2.564),T-2:carbohydrates(0.094),and control:polymers(2.185).The highest Shannon diversity index was in the M-2(3.234),followed by control(3.230)and the T-2(0.751).In addition,1.5%M.circinelloides and T.harzianum supplementation increased white shrimp muscle protein content up to 79.21%and 80.40%,respectively,compared to control(76.73%).In conclusion,using Mucor circinelloides powder as a feed supplement can improve the growth performance of white shrimp,increase the functional/probiotic bacteria:B.cereus and B.velezensis in cultur and shrimp’s intestine,and increase the protein content in shrimp muscle tissue.However,more in-depth research is needed,especially on anti-nutritional compounds from fungi that affect shrimp growth.展开更多
An 8-week feeding trial was conducted in Pacific white shrimp(Litopenaeus vannamei)to evaluate the effects of dietary choline supplementation on choline transport and metabolism,hepatopancreas histological structure a...An 8-week feeding trial was conducted in Pacific white shrimp(Litopenaeus vannamei)to evaluate the effects of dietary choline supplementation on choline transport and metabolism,hepatopancreas histological structure and fatty acid profile,and regulation of lipid metabolism.Six isonitrogenous and isolipidic diets were formulated to contain different choline levels of 2.91(basal diet),3.85,4.67,6.55,10.70 and 18.90 g/kg,respectively.A total of 960 shrimp(initial weight,1.38±0.01 g)were distributed randomly into twenty-four 250-L cylindrical fiber-glass tanks,with each diet assigned randomly to 4replicate tanks.The results indicated that dietary choline significantly promoted the deposition of choline,betaine and carnitine(P<0.05).The diameters and areas of R cells,total lipid and triglyceride contents in hepatopancreas,and triglyceride and non-esterified fatty acid contents in hemolymph were negatively correlated with dietary choline level.The contents of functional fatty acids in hepatopancreas,the activity of acetyl-CoA carboxylase(Acc),and the mRNA expression of fas,srebp and acc were highest in shrimp fed the diet containing 4.67 g/kg choline,and significantly higher than those fed the diet containing 2.91 g/kg,the lowest level of choline(P<0.05).The number of R cells,content of very lowdensity lipoprotein(VLDL),activities of carnitine palmitoyl-transferase(Cpt1),lipoprotein lipase and hepatic lipase,and the mRNA expression levels of cpt1,fabp,fatp,ldlr,and ampk in hepatopancreas increased significantly as dietary choline increased(P<0.05).In addition,hepatopancreas m RNA expression levels of ctl1,ctl2,oct1,badh,bhmt,ck,cept,and cct were generally up-regulated as dietary choline level increased(P<0.01).In conclusion,dietary choline promoted the deposition of choline and its metabolites by up-regulating genes related to choline transport and metabolism.Moreover,appropriate dietary choline level promoted the development of hepatopancreas R cells and maintained the normal accumulation of lipids required for development,while high dietary choline not only promoted hepatopancreas lipid export by enhancing VLDL synthesis,but also promoted fatty acidβ-oxidation and inhibited de novo fatty acid synthesis by activating the Ampk/Srebp signaling pathway.These findings provided further insight and understanding of the mechanisms by which dietary choline regulated lipid metabolism in L.vannamei.展开更多
To investigate the productions of biogenic amines(BAs)in Pacific white shrimp treated by compound preservatives(P,0.05 g/L quercetin,0.025 g/L 4-hexylresorcinol,and 0.025 g/L cinnamic acid)in combination with modified...To investigate the productions of biogenic amines(BAs)in Pacific white shrimp treated by compound preservatives(P,0.05 g/L quercetin,0.025 g/L 4-hexylresorcinol,and 0.025 g/L cinnamic acid)in combination with modified atmosphere packaging(M,80% CO_(2)/10% O_(2)/10% N_(2)),four groups of samples treated with or without preservatives and alone or in combination with modified atmosphere packaging(A,A+P,M,M+P)during storage at 4℃for 12 days were analyzed.Most BAs increased in all samples,especially,putrescine and cadaverine.MAP inhibited the increase of most BAs(except for tyramine)and psychrotrophic bacterial counts.The inhibitory effect of the compound preservatives on bacterial growth and BAs was limited in aerobically-and MAP-stored samples,but they retarded the production of tyramine,which accumulated more rapidly in MAP.Lowest total BAs and bacterial counts were found in sample M+P(78.3 mg/kg and 5.82 log cfu/g,day 12),indicating that the combined treatment of the preservatives and MAP could reduce the risk of disorders caused by BAs.展开更多
Viral entry into the host is the earliest stage of infection in the viral life cycle in which attachment proteins play a key role. VP31(WSV340/WSSV396), an envelope protein of white spot syndrome virus(WSSV), contains...Viral entry into the host is the earliest stage of infection in the viral life cycle in which attachment proteins play a key role. VP31(WSV340/WSSV396), an envelope protein of white spot syndrome virus(WSSV), contains an Arg-Gly-Asp(RGD) peptide domain known as a cellular attachment site. At present, the process of VP31 interacting with shrimp host cells has not been explored. Therefore, the VP31 gene was cloned into p ET30a(+), expressed in Escherichia coli strain BL21 and purifi ed with immobilized metal ion affi nity chromatography. Four gill cellular proteins of shrimp( Fenneropenaeus c hinensis) were pulled down by an affi nity column coupled with recombinant VP31(r VP31), and the amino acid sequences were identifi ed with MALDI-TOF/TOF mass spectrometry. Hemocyanin, beta-actin, arginine kinase(AK), and an unknown protein were suggested as the putative VP31 receptor proteins. SDS-PAGE showed that AK is the predominant binding protein of VP31. An i n vitro binding activity experiment indicated that recombinant AK's(r AK) binding activity with r VP31 is comparable to that with the same amount of WSSV. These results suggested that AK, as a member of the phosphagen kinase family, plays a role in WSSV infection. This is the fi rst evidence showing that AK is a binding protein of VP31. Further studies on this topic will elucidate WSSV infection mechanism in the future.展开更多
基金The National Natural Science Foundation of China under contract No.31302179the Taishan Scholar Program for Seed Industry+4 种基金the Introduction of International Advanced Agricultural Science and Technology Plan under contract No.2016-X39the Special Fund for Basic Scientific Research Business of Central Public Research Institutes under contract No.2015B04XK01China Postdoctoral Science Foundation under contract No.2015M572095Qingdao Scientific Research Foundation under contract No.14-2-4-52-jch5Jiangsu Province Science and Technology Support Project under contract No.BE2014414
文摘The aim of the present study is to detect the potential of the base population from diallel crosses of eight introduced strains of the Pacific white shrimp(Litopenaeus vannamei) for improving the yield. Heterosis and heritability were estimated for pond survival at commercial farm conditions for the base population that included 207 full-sib families from a nested mating design by artificial insemination. Among all the hybrids,the heterosis ranged from –11.37%(UA1×UA2) to 20.53%(UA3×SIN) with an average of 0.953%. The results showed that more than half of the hybrids(51.85%) have negative heterosis for survival rate, but most of the hybrids with positive heterosis have high estimates. The high proportion of negative heterosis for survival rate reminders us that the survival trait also should be considered in the crossbreeding program to avoid yield decrease. However, high positive heterosis manifested in most of the hybrids for survival indicates the usefulness of these hybrids for improving the survival to obtain higher yield by crossbreeding in this breeding program. The heritability estimate for pond survival was 0.092±0.043 when genetic groups were included in the pedigree, and it was significantly different from zero(P〈0.05). The results from this study also indicated that significant improvement for survival is possible through selection in L. vannamei.
文摘A six-week growth trial was conducted to compare the effects of different feeding strate- gies of dietary immunostimulants on the growth and immunity of white shrimp Litopenaeus vannamei (4.70 ±0.20g). Shrimps were fed with diet containing glycyrrhizin continuously, containing β -glucan continuously, discontinuously (seven days with diet containing β -gluseven days with diet without -glucan; two days with diet containing β-glucan following five days with diet without -glucan),
基金Supported by the Research Foundation for Advanced Talents, Qingdao Agricultural University (No.631109)
文摘The optimal quantity of dietary lysine (Lys) and arginine (Arg), and the optimal ratio of dietary Lys to Arg for Pacific white shrimp Litopenaeus vannamei were investigated. Coated Lys and Arg were added to a basal diet (37.99% crude protein and 7.28% crude lipid) to provide graded levels of Lys and Arg. The experimental diets contained three Lys levels (2.51%, 2.11%, and 1.70% of total diet), and three Arg levels (1.41%, 1.80%, and 2.21% of total diet) and all combinations of these levels were tested. Pacific white shrimp, with a mean weight of 3.62±0.1 g, were randomly distributed in 36 fiberglass tanks with 30 shrimp per tank and reared on the experimental diets for 50 days. After the feeding trial, the growth performance, survival, feed conversion rate (FCR), body composition and protease and lipase activities in the hepatopancreases of the experimental shrimps were determined. The results show that weight gain (WG), specific growth rate (SGR), FCR, body protein, body Lys and Arg content were significantly affected by dietary Lys and Arg (P<0.05) and improved when dietary Lys and Arg levels were 2.11% 2.51% and 1.80% 2.21%, respectively. Protease and lipase activities in the hepatopancreases of the shrimps appeared higher when dietary Lys and Arg quantities were 2.11% 2.51% and 1.80% 2.21%, although the difference was not statistically significant (P>0.05). Therefore, according to our results, the optimal Lys and Arg quantities in the diet of Pacific white shrimp, L. vannamei, were considered to be 2.11%-2.51% and 1.80%- 2.21%, respectively, and the optimal ratio to be 1:0.88-1:1.05.
基金Supported by the collaborative project of National Ministry of Agricultural Science and Technology,China(No.2012GB2E200361)the National High Technology Research and Development Program of China(863 Program)(No.2006AA10A406)the Key Laboratory of Marine Biology,Institute of Oceanology,Chinese Academy of Sciences
文摘Seven growth-related traits were measured to assess the selection response and genetic parameters of the growth of Pacific white shrimp, Litopenaeus vannamei, which had been domesticated in tanks for more than four generations. Phenotypic and genetic parameters were evaluated and fitted to an animal model. Realized response was measured from the difference between the mean growth rates of selected and control families. Realized heritability was determined from the ratio of the selection responses and selection differentials. The animal model heritability estimate over generations was 0.44±0.09 for body weight (BW), and ranged from 0.21±0.08 to 0.37±0.06 for size traits. Genetic correlations of phenotypic traits were more variable (0.51-0.97), although correlations among various traits were high (>0.83). Across generations, BW and size traits increased, while selection response and heritability gradually decreased. Selection responses were 12.28%-23.35% for harvest weight and 3.58%-13.53% for size traits. Heritability estimates ranged from 0.34±0.09 to 0.48±0.15 for harvest weight and 0.17±0.01-0.38±0.11 for size traits. All phenotypic and genetic parameters differed between various treatments. To conclude, the results demonstrated a potential for mass selection of growth traits in L. vannamei. A breeding scheme could use this information to integrate the effectiveness constituent traits into an index to achieve genetic progress.
文摘Microfungi have been explored further as supplement constituents in shrimp culture due to their rich protein,lipid,essential amino acids,fatty acids,and various bioactive compounds.The researchers have evaluated the effects of two microfungi powders(Mucor circinelloides and Trichoderma harzianum)as feed supplements on growth performance,bacterial communities,and the biomass nutritional profile of white shrimp(Litopenaeus vannamei).The results showed that commercial/artificial feed(Feng-Li)with supplementation microfungi powder had a different effect on white shrimp growth performance than control after 62 days of the grow-out period.Supplementation with 1.5%M.circinelloides powder(M-2)could improve the growth performance of white shrimp,especially the survival rate(81.33%),final body weight(5.21 g),and shrimp biomass(211.35 g).In contrast,supplementation with 1.5%T.harzianum powder(T-2)did not improve the growth performance of white shrimp compared to control(p>0.05).Furthermore,it also affected the profile of the bacterial community in culture water as well as in shrimp intestines.Supplementation with both microfungi could reduce the total number of bacteria in culture water at the end of the experiment,where the lowest number was obtained in treatment T-2(3.9×10^(5)CFU/mL),followed by M-2(9.9×10^(5)CFU/mL)and control(4.4×10^(6)CFU/mL).In the culture water,20 isolates of culturable bacteria were found during the trial,with the dominant bacteria in M-2:Bacillus cereus,Bacillus velezensis,Gordonia polyisoprenivorans,T-2:Acinetobacter sp.,Gordonia polyisoprenivorans,Micrococcus luteus.Based on average well colour development(AWCD),the highest bacterial activity was in the M-2(0.297-0.707),followed by T-2(0.226-0.717)and control(0.094-0.694).The highest substrate group utilised in M-2 and T-2 were polymers(0.896 and 1.348)and control:amines(0.100).The highest Shannon diversity index was obtained in the M-2(2.508),followed by control(2.286)and the T-2(2.157).As many as 11 isolates of culturable bacteria were found in the shrimp intestine,with dominant bacteria in M-2:Bacillus velezensis,Micrococcus luteus,Bacillus cereus,T-2:Bacillus velezensis,Micrococcus sp.2,Demequina activiva.The highest bacterial activity was in M-2(2.259),followed by control(2.020)and T-2(0.050).The highest substrate group utilisation was in M-2:polymers(2.564),T-2:carbohydrates(0.094),and control:polymers(2.185).The highest Shannon diversity index was in the M-2(3.234),followed by control(3.230)and the T-2(0.751).In addition,1.5%M.circinelloides and T.harzianum supplementation increased white shrimp muscle protein content up to 79.21%and 80.40%,respectively,compared to control(76.73%).In conclusion,using Mucor circinelloides powder as a feed supplement can improve the growth performance of white shrimp,increase the functional/probiotic bacteria:B.cereus and B.velezensis in cultur and shrimp’s intestine,and increase the protein content in shrimp muscle tissue.However,more in-depth research is needed,especially on anti-nutritional compounds from fungi that affect shrimp growth.
基金supported by the Natural Science Foundation of Zhejiang Province(LY21C190006,LY17C190002)the National Key R&D Program of China(2018YFD0900400)+2 种基金China Agriculture Research System-48(Supported by China Agriculture Research System of MOF and MARA)National Natural Science Foundation of China(32072987)the K.C.Wong Magna Fund of Ningbo University,China.
文摘An 8-week feeding trial was conducted in Pacific white shrimp(Litopenaeus vannamei)to evaluate the effects of dietary choline supplementation on choline transport and metabolism,hepatopancreas histological structure and fatty acid profile,and regulation of lipid metabolism.Six isonitrogenous and isolipidic diets were formulated to contain different choline levels of 2.91(basal diet),3.85,4.67,6.55,10.70 and 18.90 g/kg,respectively.A total of 960 shrimp(initial weight,1.38±0.01 g)were distributed randomly into twenty-four 250-L cylindrical fiber-glass tanks,with each diet assigned randomly to 4replicate tanks.The results indicated that dietary choline significantly promoted the deposition of choline,betaine and carnitine(P<0.05).The diameters and areas of R cells,total lipid and triglyceride contents in hepatopancreas,and triglyceride and non-esterified fatty acid contents in hemolymph were negatively correlated with dietary choline level.The contents of functional fatty acids in hepatopancreas,the activity of acetyl-CoA carboxylase(Acc),and the mRNA expression of fas,srebp and acc were highest in shrimp fed the diet containing 4.67 g/kg choline,and significantly higher than those fed the diet containing 2.91 g/kg,the lowest level of choline(P<0.05).The number of R cells,content of very lowdensity lipoprotein(VLDL),activities of carnitine palmitoyl-transferase(Cpt1),lipoprotein lipase and hepatic lipase,and the mRNA expression levels of cpt1,fabp,fatp,ldlr,and ampk in hepatopancreas increased significantly as dietary choline increased(P<0.05).In addition,hepatopancreas m RNA expression levels of ctl1,ctl2,oct1,badh,bhmt,ck,cept,and cct were generally up-regulated as dietary choline level increased(P<0.01).In conclusion,dietary choline promoted the deposition of choline and its metabolites by up-regulating genes related to choline transport and metabolism.Moreover,appropriate dietary choline level promoted the development of hepatopancreas R cells and maintained the normal accumulation of lipids required for development,while high dietary choline not only promoted hepatopancreas lipid export by enhancing VLDL synthesis,but also promoted fatty acidβ-oxidation and inhibited de novo fatty acid synthesis by activating the Ampk/Srebp signaling pathway.These findings provided further insight and understanding of the mechanisms by which dietary choline regulated lipid metabolism in L.vannamei.
基金The authors gratefully acknowledge the funding from the National Natural Science Foundation of China(31501551)National“13th Five-Year”Key Research and Development Program for Science and Technology Support(2016YFD0400106)+1 种基金Shanghai Science and Technology Key Project on Agriculture from Shanghai Municipal Agricultural Commission((2016)1-1)Shanghai Engineering Research Center Construction Special Fund from Shanghai Municipal Science and Technology Commission(16DZ2280300).
文摘To investigate the productions of biogenic amines(BAs)in Pacific white shrimp treated by compound preservatives(P,0.05 g/L quercetin,0.025 g/L 4-hexylresorcinol,and 0.025 g/L cinnamic acid)in combination with modified atmosphere packaging(M,80% CO_(2)/10% O_(2)/10% N_(2)),four groups of samples treated with or without preservatives and alone or in combination with modified atmosphere packaging(A,A+P,M,M+P)during storage at 4℃for 12 days were analyzed.Most BAs increased in all samples,especially,putrescine and cadaverine.MAP inhibited the increase of most BAs(except for tyramine)and psychrotrophic bacterial counts.The inhibitory effect of the compound preservatives on bacterial growth and BAs was limited in aerobically-and MAP-stored samples,but they retarded the production of tyramine,which accumulated more rapidly in MAP.Lowest total BAs and bacterial counts were found in sample M+P(78.3 mg/kg and 5.82 log cfu/g,day 12),indicating that the combined treatment of the preservatives and MAP could reduce the risk of disorders caused by BAs.
基金Supported by the National Science Foundation for Post-Doctoral Scientists of China(No.2013M541965)the International Postdoctoral Academic Exchange Program+2 种基金the Qingdao Postdoctoral Science Foundation Funded Projectthe Construction Program for“Taishan Scholarship”of Shandong Province of Chinathe Program for Chinese Outstanding Talents in Agricultural Scientific Research
文摘Viral entry into the host is the earliest stage of infection in the viral life cycle in which attachment proteins play a key role. VP31(WSV340/WSSV396), an envelope protein of white spot syndrome virus(WSSV), contains an Arg-Gly-Asp(RGD) peptide domain known as a cellular attachment site. At present, the process of VP31 interacting with shrimp host cells has not been explored. Therefore, the VP31 gene was cloned into p ET30a(+), expressed in Escherichia coli strain BL21 and purifi ed with immobilized metal ion affi nity chromatography. Four gill cellular proteins of shrimp( Fenneropenaeus c hinensis) were pulled down by an affi nity column coupled with recombinant VP31(r VP31), and the amino acid sequences were identifi ed with MALDI-TOF/TOF mass spectrometry. Hemocyanin, beta-actin, arginine kinase(AK), and an unknown protein were suggested as the putative VP31 receptor proteins. SDS-PAGE showed that AK is the predominant binding protein of VP31. An i n vitro binding activity experiment indicated that recombinant AK's(r AK) binding activity with r VP31 is comparable to that with the same amount of WSSV. These results suggested that AK, as a member of the phosphagen kinase family, plays a role in WSSV infection. This is the fi rst evidence showing that AK is a binding protein of VP31. Further studies on this topic will elucidate WSSV infection mechanism in the future.