An Ha-ras oncogene was isolated from a cell line of gastric carcinoma called BGE-823 in order to elucidate genetic control and the influence of DNA sequences. The oncogene was cloned and identified as a single nucleot...An Ha-ras oncogene was isolated from a cell line of gastric carcinoma called BGE-823 in order to elucidate genetic control and the influence of DNA sequences. The oncogene was cloned and identified as a single nucleotide substitution of thymine for guanine in the 12th codon through the sequencing of its first axon. We compared the differences of expression and regulation between the transformed Ha-ras cells and untransformed parent cells. Data indicated that the expression of Ha-ras in the transformed cells was five-fold higher than in the untransformed cells and that the Ha-ras gene in the former was hypersensitive toward DNase I. In addition, a nuclear protein of 35 kilodaltons bound strongly to the 2.5 Kb fragment located upstream of the 6.6 Kb Ha-ras gene and contained a CC rich region. These results suggest that there might be another mechanism of activation for the ras gene besides point mutation.展开更多
It is observed by in situ stain that LDH (1 5) ...nNAD + can probably enter the nucleopore and can be bound bound specifically with the genes that encode them. During the in vitro expression, the dilution of heart nuc...It is observed by in situ stain that LDH (1 5) ...nNAD + can probably enter the nucleopore and can be bound bound specifically with the genes that encode them. During the in vitro expression, the dilution of heart nuclear DNA fragments could enhance the expression activity of LDH/DNA and the amount of expressed LDH (1 5) is in proportion to the amount of dissociable LDH (1 5) on the LDH/DNA. With the integration of 14C Leu to the proteins, it is also observed that the addition of LDH (1 5) ...nNAD + can suppress the in vitro expression activity of LDH/DNA. AFM observation shows that the regulation sequence at the both ends of active genes may be bound with such active factors as proteins encoded by the genes which probably is the main molecular switch of gene expression and regulation we have been always searching for. Our work shows the prospective application of the combination of AFM and isotope labeling in the research of biological reaction.展开更多
The fibroin gene expression pattern and regulation of the posterior silkgland were studied by means of expressed sequence tags(ESTs)using the first and fifth day larvae of the fifth instar of silkworm,Bombyx mori L(st...The fibroin gene expression pattern and regulation of the posterior silkgland were studied by means of expressed sequence tags(ESTs)using the first and fifth day larvae of the fifth instar of silkworm,Bombyx mori L(strain:C 108).The results showed that there were 911 repetitive ESTs and 1950 single sequences(Singlets)among total 2861 consentient sequences,which were spliced.1335 sequences were identified and the other 1526 were unknown.5560 sequences(55.89%)in the posterior silkgland cell of the silkworm were new ESTs without homology with EST data published by Mita et al.The number of repetitive ESTs and single sequences from the first day larvae of the fifth instar was double more than that of the fifth day of the same instar in the silkworms.The unigenes which were more than 50 in repetitive EST size(contig size)came to only about 0.5%in total consentient sequences.There were significant differences between gene expression frequencies,and expressed genes were related to fibroin synthesis and its secretion and fibroin composition.Comparing the fifth day with the first day of the fifth instar,the genes-expressed quantity of fibroin heavy-chain gene was 18 fold higher,fibroin light-chain gene 9 fold and fibroin P52 gene 8 fold.508 genes functioned for cellular component and 315 for enzyme after function tracing.These results implied that the gene expression of the first day was mainly for preparation for fibroin synthesis except for the growth of silkgland cells,and the gene expression of the fifth day of the fifth instar was mainly for synthesizing and excreting fibroin.Because the ratio of heavy chain,light chain and p25 of fibroin was not 6:6:1 as theoretically expected,or its special H-chain structure,the H-chain gene was not easy to detect through EST technique.Most of genes among total 2861 consentient sequences functioned for fibroin synthesis and secretion.This suggested the fibroin synthesis and secretion procedure of the posterior silkgland was more complex than the knowledge we have.展开更多
Upstream regulatory region and flanking DMA of yellow gene were isolated and cloned from a Drosophila genomic library. A vector containing yellow gene and regulatory elements was constructed using the recombinant DNA ...Upstream regulatory region and flanking DMA of yellow gene were isolated and cloned from a Drosophila genomic library. A vector containing yellow gene and regulatory elements was constructed using the recombinant DNA technique. Then this vector was integrated into Drosophila genome by genetic transformation. Using both FLP/FRT and Cre/LoxP site-specific recombination systems, two new yellow alleles were created at the same position in the genome of transgenic flies. Results from genetic and molecular analysis indicated that transcriptional enhancers regulate the developmental expression of the transgene. Furthermore, interactions between new-created yellow alleles were observed. Such interactions can influence markedly the expression of yellow gene during development. This effect may also be a form of enhancer-mediated gene expression.展开更多
文摘An Ha-ras oncogene was isolated from a cell line of gastric carcinoma called BGE-823 in order to elucidate genetic control and the influence of DNA sequences. The oncogene was cloned and identified as a single nucleotide substitution of thymine for guanine in the 12th codon through the sequencing of its first axon. We compared the differences of expression and regulation between the transformed Ha-ras cells and untransformed parent cells. Data indicated that the expression of Ha-ras in the transformed cells was five-fold higher than in the untransformed cells and that the Ha-ras gene in the former was hypersensitive toward DNase I. In addition, a nuclear protein of 35 kilodaltons bound strongly to the 2.5 Kb fragment located upstream of the 6.6 Kb Ha-ras gene and contained a CC rich region. These results suggest that there might be another mechanism of activation for the ras gene besides point mutation.
文摘It is observed by in situ stain that LDH (1 5) ...nNAD + can probably enter the nucleopore and can be bound bound specifically with the genes that encode them. During the in vitro expression, the dilution of heart nuclear DNA fragments could enhance the expression activity of LDH/DNA and the amount of expressed LDH (1 5) is in proportion to the amount of dissociable LDH (1 5) on the LDH/DNA. With the integration of 14C Leu to the proteins, it is also observed that the addition of LDH (1 5) ...nNAD + can suppress the in vitro expression activity of LDH/DNA. AFM observation shows that the regulation sequence at the both ends of active genes may be bound with such active factors as proteins encoded by the genes which probably is the main molecular switch of gene expression and regulation we have been always searching for. Our work shows the prospective application of the combination of AFM and isotope labeling in the research of biological reaction.
文摘The fibroin gene expression pattern and regulation of the posterior silkgland were studied by means of expressed sequence tags(ESTs)using the first and fifth day larvae of the fifth instar of silkworm,Bombyx mori L(strain:C 108).The results showed that there were 911 repetitive ESTs and 1950 single sequences(Singlets)among total 2861 consentient sequences,which were spliced.1335 sequences were identified and the other 1526 were unknown.5560 sequences(55.89%)in the posterior silkgland cell of the silkworm were new ESTs without homology with EST data published by Mita et al.The number of repetitive ESTs and single sequences from the first day larvae of the fifth instar was double more than that of the fifth day of the same instar in the silkworms.The unigenes which were more than 50 in repetitive EST size(contig size)came to only about 0.5%in total consentient sequences.There were significant differences between gene expression frequencies,and expressed genes were related to fibroin synthesis and its secretion and fibroin composition.Comparing the fifth day with the first day of the fifth instar,the genes-expressed quantity of fibroin heavy-chain gene was 18 fold higher,fibroin light-chain gene 9 fold and fibroin P52 gene 8 fold.508 genes functioned for cellular component and 315 for enzyme after function tracing.These results implied that the gene expression of the first day was mainly for preparation for fibroin synthesis except for the growth of silkgland cells,and the gene expression of the fifth day of the fifth instar was mainly for synthesizing and excreting fibroin.Because the ratio of heavy chain,light chain and p25 of fibroin was not 6:6:1 as theoretically expected,or its special H-chain structure,the H-chain gene was not easy to detect through EST technique.Most of genes among total 2861 consentient sequences functioned for fibroin synthesis and secretion.This suggested the fibroin synthesis and secretion procedure of the posterior silkgland was more complex than the knowledge we have.
基金the National High Technology Program For Young Scientists and Life Science Specific Fund (stz98-2-05) and Knowledge Innovation Foundation of Chinese Academy of Sciences.
文摘Upstream regulatory region and flanking DMA of yellow gene were isolated and cloned from a Drosophila genomic library. A vector containing yellow gene and regulatory elements was constructed using the recombinant DNA technique. Then this vector was integrated into Drosophila genome by genetic transformation. Using both FLP/FRT and Cre/LoxP site-specific recombination systems, two new yellow alleles were created at the same position in the genome of transgenic flies. Results from genetic and molecular analysis indicated that transcriptional enhancers regulate the developmental expression of the transgene. Furthermore, interactions between new-created yellow alleles were observed. Such interactions can influence markedly the expression of yellow gene during development. This effect may also be a form of enhancer-mediated gene expression.
