Bacillus thuringiensis (Bt) strain C002 contains crylAa, cry2Ab, crylCa insecticidal crystal genes and an unkown gene cryX, among which crylCa is located in a 6 -9 kb EcoR I fragment of the chromosomal DNA. The total ...Bacillus thuringiensis (Bt) strain C002 contains crylAa, cry2Ab, crylCa insecticidal crystal genes and an unkown gene cryX, among which crylCa is located in a 6 -9 kb EcoR I fragment of the chromosomal DNA. The total DNA and the plasmids DNA libraries of C002 were constructed in Bt-E. coli shuttle plasmid pHT315 by inserting 6 - 9 kb chromosomal and plasmid DNA fragments prepared respectively with EcoR I complete and 5au3A I partial digestion. On the basis of every 50 transformants pooled together from 5-10 tubes, the pools containing about 2 000 transformants from the plasmids DNA library and 400 transformants from the total DNA library were rapidly screened by PCR-RFLP. Clones containing crylAa, cryX, crylCa , and cry2Ab were isolated and named as pHT-1Aa, pHT-X, pHT-1Ca and pHT-2Ab respectively. Restriction analysis indicated that pHT-1Aa, pHT-1Ca and pHT-2Ab had the typical physical map of the homologous cry genes. Furthermore, each plasmid was transferred into Bt acrystalliferous strain cryB- by eletropora-tion. SDS-PAGE result showed that transformant of pHT-1Ca expressed 130 kDa protein and bioassay result proved its high toxicity against Spodotera exigua 1st instar larvae with 100% corrected motality.展开更多
A method based on degenerate Oligo primed polymerase chain reaction (PCR) and random amplification of cDNA end (RACE) PCR for cloning a full length cDNA is described. An Amorpha fruticosa cDNA clone encoding UDP gluco...A method based on degenerate Oligo primed polymerase chain reaction (PCR) and random amplification of cDNA end (RACE) PCR for cloning a full length cDNA is described. An Amorpha fruticosa cDNA clone encoding UDP glucose pyrophosphorylase (UGP), a key enzyme producing UDP glucose in the synthesis of sucrose and cellulose, is cloned by using this method. We design 5’ RACE primers based on UGPA1 fragment, which obtains from degenerate PCR. Inverse PCR and nested PCR enable cloning of the remainder 5’ and 3’ end fragments of the gene. The deduced amino acid sequence exhibits significant homology with the other UGP genes cloned. This method is more simple and inexpensive than screening cDNA library, and can be easily adapted to clone other genes.展开更多
The differential hybridization technique hasbeen widely used to identify genes that are dif-ferentially expressed.However,this approachhas several drawbacks.First,the screeningprocedures are rather labor-intensive and...The differential hybridization technique hasbeen widely used to identify genes that are dif-ferentially expressed.However,this approachhas several drawbacks.First,the screeningprocedures are rather labor-intensive and time-consuming.Second,the amount of phageDNAs transferred onto the two filters may notbe equivalent,which leads to an inaccurate se-lection of a positive clone.Third,isolation ofphage DNA is slow and cumbersome.Here,aPCR based differential screening method that展开更多
文摘Bacillus thuringiensis (Bt) strain C002 contains crylAa, cry2Ab, crylCa insecticidal crystal genes and an unkown gene cryX, among which crylCa is located in a 6 -9 kb EcoR I fragment of the chromosomal DNA. The total DNA and the plasmids DNA libraries of C002 were constructed in Bt-E. coli shuttle plasmid pHT315 by inserting 6 - 9 kb chromosomal and plasmid DNA fragments prepared respectively with EcoR I complete and 5au3A I partial digestion. On the basis of every 50 transformants pooled together from 5-10 tubes, the pools containing about 2 000 transformants from the plasmids DNA library and 400 transformants from the total DNA library were rapidly screened by PCR-RFLP. Clones containing crylAa, cryX, crylCa , and cry2Ab were isolated and named as pHT-1Aa, pHT-X, pHT-1Ca and pHT-2Ab respectively. Restriction analysis indicated that pHT-1Aa, pHT-1Ca and pHT-2Ab had the typical physical map of the homologous cry genes. Furthermore, each plasmid was transferred into Bt acrystalliferous strain cryB- by eletropora-tion. SDS-PAGE result showed that transformant of pHT-1Ca expressed 130 kDa protein and bioassay result proved its high toxicity against Spodotera exigua 1st instar larvae with 100% corrected motality.
文摘A method based on degenerate Oligo primed polymerase chain reaction (PCR) and random amplification of cDNA end (RACE) PCR for cloning a full length cDNA is described. An Amorpha fruticosa cDNA clone encoding UDP glucose pyrophosphorylase (UGP), a key enzyme producing UDP glucose in the synthesis of sucrose and cellulose, is cloned by using this method. We design 5’ RACE primers based on UGPA1 fragment, which obtains from degenerate PCR. Inverse PCR and nested PCR enable cloning of the remainder 5’ and 3’ end fragments of the gene. The deduced amino acid sequence exhibits significant homology with the other UGP genes cloned. This method is more simple and inexpensive than screening cDNA library, and can be easily adapted to clone other genes.
文摘The differential hybridization technique hasbeen widely used to identify genes that are dif-ferentially expressed.However,this approachhas several drawbacks.First,the screeningprocedures are rather labor-intensive and time-consuming.Second,the amount of phageDNAs transferred onto the two filters may notbe equivalent,which leads to an inaccurate se-lection of a positive clone.Third,isolation ofphage DNA is slow and cumbersome.Here,aPCR based differential screening method that
