In the present paper, RAPD was used to study the genetic polymorphism of fisheswith different genome combinations. Our results indicated that four of the 26 random primersproduced distinct and reproducible electrophor...In the present paper, RAPD was used to study the genetic polymorphism of fisheswith different genome combinations. Our results indicated that four of the 26 random primersproduced distinct and reproducible electrophoretic patterns which were genome-specific andcould distinguish different biotypes. This enabled us to derive a diagnostic profile, from whichwe constructed a molecular marker key for different biotypes. By the analysis of the data ofRAPD patterns, the genetic relationship was constructed with UPGMA (unweighted pair-groupmethod with arithmetical averages). Our experiments also concluded that RAPD was moresuccessful in variety identification than protein polymorphism analysis and serohematology for itstechnological simplicity and sensitivity.展开更多
Since late 2005, the swine industry in Shandong province has experienced a significant increase in postweaning multisystemic wasting syndrome （PMWS）. Porcine circovirus type 2 （PCV2） is one of the major etiologic ...Since late 2005, the swine industry in Shandong province has experienced a significant increase in postweaning multisystemic wasting syndrome （PMWS）. Porcine circovirus type 2 （PCV2） is one of the major etiologic agents of PMWS. In order to understand the genetic diversity of PCV2 in swine herds in Shandong province, we sequenced six complete genomes of PCV2 between 2005 and 2007. Sequence analysis revealed that all the six PCV2 strains belonged to one genotype （named PCV 2b）. The deduced amino acid sequences of the replication associated protein （coded by ORFI） showed that all the six PCV2 strains belonged to genotype 2a and could be further divided into two clusters. Based on the analysis of the capsid protein （coded by ORF2）, the six PCV2 strains belonged to genotype 2b. All the six strains belonged to recombinant viruses between genotype PCV2a and genotype PCV2b. This study implied that such recombinant PCV2 spread widely in Shandong area and might be the reason that pig death rate associated with PMWS increased in recent years.展开更多
An ideal surrogate host for heterologous production of various natural products is expected to have efficient nutrient utilization,fast growth,abundant precursors and energy supply,and a pronounced gene expression.Str...An ideal surrogate host for heterologous production of various natural products is expected to have efficient nutrient utilization,fast growth,abundant precursors and energy supply,and a pronounced gene expression.Streptomyces albus BK3-25 is a high-yield industrial strain producing type-Ⅰ polyketide sahnomycin,with a unique ability of bean oil utilization.Its potential of being a surrogate host for heterologous production of PKS was engineered and evaluated herein.Firstly,introduction of a three-gene cassette for the biosynthesis of ethylmalonyl-CoA resulted in accumulation of ethylmalonyl-CoA precursor and sahnomycin,and subsequent deletion of the sahnomycin biosynthetic gene cluster resulted in a host with rich supplies of common polyketide precursors,including malonyl-CoA,methylmalonyl-CoA,and ethylmalonyl-CoA.Secondly,the energy and reducing force were measured,and the improved accumulation of ATP and NADPH was observed in the mutant.Furthermore,the strength of a series of selected endogenous promoters based on microarray data was assessed at different growth phases,and a strong constitutive promoter was identified,providing a useful tool for further engineered gene expression.Finally,the potential of the BK3-25 derived host ZXJ-6 was evaluated with the introduction of the actinorhodin biosynthetic gene cluster from Streptomyces coelicolor,and the heterologous production of actinorhodin was obtained.This work clearly indicated the potential of the high-yield sahnomycin producer as a surrogate host for heterologous production of polyketides,although more genetic manipulation should be conducted to streamline its performance.展开更多
文摘In the present paper, RAPD was used to study the genetic polymorphism of fisheswith different genome combinations. Our results indicated that four of the 26 random primersproduced distinct and reproducible electrophoretic patterns which were genome-specific andcould distinguish different biotypes. This enabled us to derive a diagnostic profile, from whichwe constructed a molecular marker key for different biotypes. By the analysis of the data ofRAPD patterns, the genetic relationship was constructed with UPGMA (unweighted pair-groupmethod with arithmetical averages). Our experiments also concluded that RAPD was moresuccessful in variety identification than protein polymorphism analysis and serohematology for itstechnological simplicity and sensitivity.
文摘Since late 2005, the swine industry in Shandong province has experienced a significant increase in postweaning multisystemic wasting syndrome （PMWS）. Porcine circovirus type 2 （PCV2） is one of the major etiologic agents of PMWS. In order to understand the genetic diversity of PCV2 in swine herds in Shandong province, we sequenced six complete genomes of PCV2 between 2005 and 2007. Sequence analysis revealed that all the six PCV2 strains belonged to one genotype （named PCV 2b）. The deduced amino acid sequences of the replication associated protein （coded by ORFI） showed that all the six PCV2 strains belonged to genotype 2a and could be further divided into two clusters. Based on the analysis of the capsid protein （coded by ORF2）, the six PCV2 strains belonged to genotype 2b. All the six strains belonged to recombinant viruses between genotype PCV2a and genotype PCV2b. This study implied that such recombinant PCV2 spread widely in Shandong area and might be the reason that pig death rate associated with PMWS increased in recent years.
基金supported by grants from the National Natural Science Foundation of China(21661140002 and 31470157)the Ministry of Science and Technology of China(2012CB721005 and 2012AA022107)
文摘An ideal surrogate host for heterologous production of various natural products is expected to have efficient nutrient utilization,fast growth,abundant precursors and energy supply,and a pronounced gene expression.Streptomyces albus BK3-25 is a high-yield industrial strain producing type-Ⅰ polyketide sahnomycin,with a unique ability of bean oil utilization.Its potential of being a surrogate host for heterologous production of PKS was engineered and evaluated herein.Firstly,introduction of a three-gene cassette for the biosynthesis of ethylmalonyl-CoA resulted in accumulation of ethylmalonyl-CoA precursor and sahnomycin,and subsequent deletion of the sahnomycin biosynthetic gene cluster resulted in a host with rich supplies of common polyketide precursors,including malonyl-CoA,methylmalonyl-CoA,and ethylmalonyl-CoA.Secondly,the energy and reducing force were measured,and the improved accumulation of ATP and NADPH was observed in the mutant.Furthermore,the strength of a series of selected endogenous promoters based on microarray data was assessed at different growth phases,and a strong constitutive promoter was identified,providing a useful tool for further engineered gene expression.Finally,the potential of the BK3-25 derived host ZXJ-6 was evaluated with the introduction of the actinorhodin biosynthetic gene cluster from Streptomyces coelicolor,and the heterologous production of actinorhodin was obtained.This work clearly indicated the potential of the high-yield sahnomycin producer as a surrogate host for heterologous production of polyketides,although more genetic manipulation should be conducted to streamline its performance.
