Genomic DNAs of metallothionein Ⅰ and Ⅱ in Caenorhabditis elegans (CeMT-Ⅰand CeMT-Ⅱ) were isolated by YAC library/polytene filter hybridization followed by subcloning of corresponding cosmid clones. Both genes are...Genomic DNAs of metallothionein Ⅰ and Ⅱ in Caenorhabditis elegans (CeMT-Ⅰand CeMT-Ⅱ) were isolated by YAC library/polytene filter hybridization followed by subcloning of corresponding cosmid clones. Both genes are mapped at chromosome V. Although the similarities of 5'-flanking regions and coding regions have shown only 55-58%, the introns are split at the same position in both genes, indicating that these two genes are originally from the same gene. While several metal responsive elements are conserved among eukaryotes, only one metal responsive element was found in the promoter region in CeMT-Ⅱ and not in CeMT-Ⅰ. Indced, neither of 5'-flanking regions of CeMT-Ⅰ nor CeMT-Ⅱ connected to chloramphenicol acetyltransferase reporter gene is responsive to heavy metals in mammalian culture cells by transient transfection analysis. These results would suggest that the metal regulatory factors in C.elegans might be different from those conserved in invertebrates and vertebrates, although the MTs in C elegans revealed the similarities to mammalian MTs in several points展开更多
Metallothionein (MT) gene has an important role in the detoxification of toxic metals especially some heavy metals. Based on the published sequences of MT genes from Agaricus bisporus, Garnoderma lucidum, Taiwanofungu...Metallothionein (MT) gene has an important role in the detoxification of toxic metals especially some heavy metals. Based on the published sequences of MT genes from Agaricus bisporus, Garnoderma lucidum, Taiwanofungus camphoratus and Paxillus involutus as a type of the edible or medical mushroom in NCBI database, their molecular structures, physiological functions and evolutionary relationship were analyzed using the bioinformatics methods. Results showed that AbMT, GlMT, TcMT and PiMT genes contained complete open reading frame (ORF) and their theoretical points of the last three encoding proteins were higher than 7.0. AbMT, GlMT, TcMT and PiMT were relatively rich in random coil and extended strand, but transmembrane helices and signal peptides were not found. 4 MTs were mainly localized in cell nucleus (over 60%) and their cellular functions might have some relation to central intermediary metabolism. Multiple sequence alignment indicated relatively high identity (more than 52%) and short genetic distances (lower than 0.900) among 4 MT nucleotide sequences. Abundant genetic diversity and strong codon bias were found based on the halotype diversity, average number of nucleotide differences, nucleotide diversity, effective number of codons, codon bias index and scaled chisquare. Simultaneously, we deduced that 4 MT genes during molecular evolution were under positive selection. The present study might provide basis for further investigation of MTs molecular mechanisms and genetic laws.展开更多
Metallothioneins(MTs) are normally considered to be sensitive indicators of heavy metal pollution, but it is less clear whether the MT gene can actively respond to other environmental stresses. In this study, an MT m ...Metallothioneins(MTs) are normally considered to be sensitive indicators of heavy metal pollution, but it is less clear whether the MT gene can actively respond to other environmental stresses. In this study, an MT m RNA molecular sequence of 471 bp(full length) was identified in marine cultured black porgy(Acanthopagrus schlegelii), encoding 60 amino acids containing 20 cysteine residues. The MT sequence was highly homologous to that of other fish belonging to the MT superfamily type 1 family. The three dimensional structure of the deduced MT peptide was composed of two metal-binding domains capable of ligating divalent heavy metals. The MT m RNA transcripts were detected in the 11 tested tissues and the highest quantity was present in the liver. Stresses by two factors, benzo[a]pyrene(B[a]p) exposure and bacterial challenge, were evaluated on MT gene expression. The level of MT gene transcripts in the liver significantly declined 24 h post B[a]p exposure and the quantity was significantly correlated with the exposure time during a 24 h period. In contrast, MT gene expression in the liver was significantly increased 48 h post bacterial infection and the quantity was significantly correlated with the infection time during this period of 48 h. Our results indicated that MT gene expression in black porgy liver was sensitive to environmental stresses other than just the heavy metal pollution reported, suggesting that the development of a reliable biomarker for heavy metal pollution will be more complex than expected.展开更多
Metallothioneins (MTs) are a group of low molecular mass and cysteine-rich proteins that can chelate heavy-metal ions. In this paper,Northern blot analysis was used to investigate the influence of lead stress on the e...Metallothioneins (MTs) are a group of low molecular mass and cysteine-rich proteins that can chelate heavy-metal ions. In this paper,Northern blot analysis was used to investigate the influence of lead stress on the expression patterns of 10 rice class I MT genes (OsMT-Is) in rice seedlings. With the ex-ception of OsMT-I-3b,the data demonstrate dynamic changes of 9 OsMT-I transcripts in response to Pb2+ treatment in rice seedling roots. Of these genes,transcription of OsMT-I-1a,OsMT-I-1b,OsMT-I-2c,OsMT-I-4a,OsMT-I-4b and OsMT-I-4c increased significantly,while transcription of OsMT-I-2a and OsMT-I-3a increased marginally. In contrast,the expression of OsMT-I-2b was inhibited. Pb2+ induced the expression of 6 OsMT-I genes in seedling shoots,but had no obvious effects on the expression of OsMT-I-1a,OsMT-I-1b,OsMT-I-4a and OsMT-I-4b. All the 10 OsMT-Is had enhanced lead tolerance when heterologously expressed in lead-sensitive yeast mutant cells. These results provide an expression profile of the rice MT gene family in response to Pb2+ stress in rice seedlings and demonstrate in-creased lead tolerance in sensitive yeast mutant cells expressing OsMT-Is. This study lays a foundation for further analysis of the role of the rice MT gene family in respond to Pb2+ stress.展开更多
Objective To study the gene expression of metallothionein 1 （MT-1） isoforms in human peripheral blood lymphocytes （HPBLs）. Methods The expression of mRNA representing the seven active MT-I genes was determined in ...Objective To study the gene expression of metallothionein 1 （MT-1） isoforms in human peripheral blood lymphocytes （HPBLs）. Methods The expression of mRNA representing the seven active MT-I genes was determined in HPBLs by quantitative RT-PCR before and after exposure to cadmium. Results Basal expressions of MT-IX, and MT-1A in HPBLs were similar to expression of housekeeping gene. In contrast, the basal gene expressions of MT- 1 H, IF, 1E, and 1G were a little transcripts in human HPBLs. No signal was detected for MT-1B. There was a sex difference （P〈0.05）. in basal gene expression of MT-1E. The levels of gene expression of MT-1A, 1E, IF, 1G, 1H, and 1X increased, but the level of MT-1B did not increase after exposure to cadmium. Conclusions Gene expressions of MT-1 G, MT-1 H, MT-1 F, and MT-1X in HPBLs can be used as a potential biomarker of cadmium exposure.展开更多
I. INTRODUCTIONMetallothioneins(MT) are ubiquitously distributed in animal and plant kingdoms. They are cysteine-rich proteins that specifically bind heavy metal ions, such as cadmium, zinc, mercury and copper. The hi...I. INTRODUCTIONMetallothioneins(MT) are ubiquitously distributed in animal and plant kingdoms. They are cysteine-rich proteins that specifically bind heavy metal ions, such as cadmium, zinc, mercury and copper. The high expression of the MT gene could be induced by heavy metals in vitro and in vivo. The first transgenic mice obtained by Palmiter et al. in 1982 were introduced with an exogenous growth hormnoe gene展开更多
1 Introduction Metallothioneins (MTs) are a family of low-molecular weight heavy metal binding proteins, unique in their high cystein content. MTs are ubiquitously distributed in the eukaryote from yeast to human. It ...1 Introduction Metallothioneins (MTs) are a family of low-molecular weight heavy metal binding proteins, unique in their high cystein content. MTs are ubiquitously distributed in the eukaryote from yeast to human. It is an experimental model emphasized during researching gene expression and regulation of animal cells. In order to provide inducible regulatory elements for transgenosis livestock, we cloned bovine MT genes. At least four members of bovine MT family have been discovered. In this note, one gene (bMTc) of展开更多
From Tetrahymena thermophila （strain BF5）, the coding region of Cd-MT gene was cloned and sequenced. and identified as MTT1 isoform. A serial duplicate structure is discovered in its amino acid sequence, which separ...From Tetrahymena thermophila （strain BF5）, the coding region of Cd-MT gene was cloned and sequenced. and identified as MTT1 isoform. A serial duplicate structure is discovered in its amino acid sequence, which separates the coding region into three parts （Part 1：7-61; Part 2：64-118; Part 3：122-162）. The alignments among them and comparison with the corresponding parts of MT1 isoform suggest that MT1 and MTT1 isoforms both come from the same ancient gene that is homologous to Part 1, and Cd-MTs of Tetrahymena are aroused by such ancient gene duplication. The prediction of secondary structures and the analysis of the disulfide-bonding state of cysteine show that there are a lot of differences between MT1 and MTT1 isoforms, which maybe relate to their function mechanism.展开更多
金属硫蛋白(metallothionein,MT)MT3是人体中参与重金属解毒的主要蛋白,前期研究表明啤酒酵母(Saccharomyces c erevisiae)α因子信号肽(MF-α)介导重组蛋白EGFP分泌到植物体外。但是目前还没有研究报道转基因植物中过量表达分泌型MT3...金属硫蛋白(metallothionein,MT)MT3是人体中参与重金属解毒的主要蛋白,前期研究表明啤酒酵母(Saccharomyces c erevisiae)α因子信号肽(MF-α)介导重组蛋白EGFP分泌到植物体外。但是目前还没有研究报道转基因植物中过量表达分泌型MT3对植物重金属镉(Cd)的富集能力是否有影响。本研究通过人工方法合成MF-α信号肽、增强型绿色荧光蛋白(enhanced green fluorescent protein,EGFP)和MT3的融合基因MF-α-EGFP-MT3,构建该融合基因的植物表达载体pK-35S-MF-α-EGFP-MT3,转化野生型(WT)烟草和天竺葵获得转基因植物。通过电化学方法检测转基因植物MT3转录水平、转基因植物根系分泌液中EGFP-MT3蛋白的水平。用Cd溶液处理转基因植物,通过表型观察和电化学方法检测根、茎和叶中Cd的含量。结果表明,转基因烟草和天竺葵中都有MT3基因的转录;且根系分泌EGFP-MT3蛋白的量大约为0.45~0.68 mg·g-1(以鲜质量计)。100μmol·L-1的Cd溶液处理转基因烟草植株,表型变化分析发现转基因植株受损情况低于WT,近根部叶片叶绿素含量显著高于WT,说明EGFP-MT3的分泌可降低Cd的毒害作用。转基因烟草植株根、茎和叶片对Cd的富集量比WT高约40%。用50μmol·L-1的Cd溶液处理转基因天竺葵植株,结果表明转基因植株根对Cd的富集量比WT高约30%,茎对Cd的富集量比WT高约4倍。以上结果证明过量表达EGFP-MT3可以提高转基因烟草和天竺葵对Cd的富集能力,可能是EGFP-MT3分泌根系表面增加转基因植物根系对Cd的吸附作用,同时在转基因植物组织细胞内积累的EGFP-MT3也可增加植物组织对Cd的富集作用。展开更多
Zostera marina, a monocotyledonous angiosperm, is one of the most important seagrass species. To inves- tigate the salt-tolerance mechanism and discover salt-tolerant genes in Z. marina, a cDNA library was con- struct...Zostera marina, a monocotyledonous angiosperm, is one of the most important seagrass species. To inves- tigate the salt-tolerance mechanism and discover salt-tolerant genes in Z. marina, a cDNA library was con- structed. Single-pass sequencing of the 5＇ ends of 4 081 clones yielded 4 002 high quality expressed sequence tags （ESTs）, which were assembled into 241 contigs and 1 673 singletons, representing 1 914 unigenes. The average length of the ESTs was 582 bp, with sizes ranging from 100-1 500 bp. Basic Local Alignment Search Tool （BLASTX） analysis revealed that 1 664 unigenes had significant homology to known genes in the Na- tional Center for Biotechnology Information （NCBI） non-redundant （nr） database （E-value≤5-10）. Among them, the two most abundant genes encoded metallothionein （157 ESTs） and chlorophyll a/b-binding pro- tein （38 ESTs）, accounting for 7.1% and 1.7% of the total ESTs, respectively. Using Kyoto Encyclopedia of Genes and Genomes （KEGG）, 1 462 unigenes were assigned to 1 161 pathways （E-value≤5-10）. A total of 938 unigenes were assigned Gene Ontology （GO） terms based on the GO hierarchy analysis, and InterProScan searches recognized 1 003 InterPro families. Three genes for metallothionein in Z. marina that belonged to Class II was identified. Results of this study will improve understanding of the molecular mechanisms of saline tolerance in Z. marina.展开更多
文摘Genomic DNAs of metallothionein Ⅰ and Ⅱ in Caenorhabditis elegans (CeMT-Ⅰand CeMT-Ⅱ) were isolated by YAC library/polytene filter hybridization followed by subcloning of corresponding cosmid clones. Both genes are mapped at chromosome V. Although the similarities of 5'-flanking regions and coding regions have shown only 55-58%, the introns are split at the same position in both genes, indicating that these two genes are originally from the same gene. While several metal responsive elements are conserved among eukaryotes, only one metal responsive element was found in the promoter region in CeMT-Ⅱ and not in CeMT-Ⅰ. Indced, neither of 5'-flanking regions of CeMT-Ⅰ nor CeMT-Ⅱ connected to chloramphenicol acetyltransferase reporter gene is responsive to heavy metals in mammalian culture cells by transient transfection analysis. These results would suggest that the metal regulatory factors in C.elegans might be different from those conserved in invertebrates and vertebrates, although the MTs in C elegans revealed the similarities to mammalian MTs in several points
文摘Metallothionein (MT) gene has an important role in the detoxification of toxic metals especially some heavy metals. Based on the published sequences of MT genes from Agaricus bisporus, Garnoderma lucidum, Taiwanofungus camphoratus and Paxillus involutus as a type of the edible or medical mushroom in NCBI database, their molecular structures, physiological functions and evolutionary relationship were analyzed using the bioinformatics methods. Results showed that AbMT, GlMT, TcMT and PiMT genes contained complete open reading frame (ORF) and their theoretical points of the last three encoding proteins were higher than 7.0. AbMT, GlMT, TcMT and PiMT were relatively rich in random coil and extended strand, but transmembrane helices and signal peptides were not found. 4 MTs were mainly localized in cell nucleus (over 60%) and their cellular functions might have some relation to central intermediary metabolism. Multiple sequence alignment indicated relatively high identity (more than 52%) and short genetic distances (lower than 0.900) among 4 MT nucleotide sequences. Abundant genetic diversity and strong codon bias were found based on the halotype diversity, average number of nucleotide differences, nucleotide diversity, effective number of codons, codon bias index and scaled chisquare. Simultaneously, we deduced that 4 MT genes during molecular evolution were under positive selection. The present study might provide basis for further investigation of MTs molecular mechanisms and genetic laws.
基金sponsored by the National Natural Science Foundation of China (grant No.31100376)the Shanghai Municipal Education Commission (grant No.14YZ001)the MEL Visiting Fellowship Program
文摘Metallothioneins(MTs) are normally considered to be sensitive indicators of heavy metal pollution, but it is less clear whether the MT gene can actively respond to other environmental stresses. In this study, an MT m RNA molecular sequence of 471 bp(full length) was identified in marine cultured black porgy(Acanthopagrus schlegelii), encoding 60 amino acids containing 20 cysteine residues. The MT sequence was highly homologous to that of other fish belonging to the MT superfamily type 1 family. The three dimensional structure of the deduced MT peptide was composed of two metal-binding domains capable of ligating divalent heavy metals. The MT m RNA transcripts were detected in the 11 tested tissues and the highest quantity was present in the liver. Stresses by two factors, benzo[a]pyrene(B[a]p) exposure and bacterial challenge, were evaluated on MT gene expression. The level of MT gene transcripts in the liver significantly declined 24 h post B[a]p exposure and the quantity was significantly correlated with the exposure time during a 24 h period. In contrast, MT gene expression in the liver was significantly increased 48 h post bacterial infection and the quantity was significantly correlated with the infection time during this period of 48 h. Our results indicated that MT gene expression in black porgy liver was sensitive to environmental stresses other than just the heavy metal pollution reported, suggesting that the development of a reliable biomarker for heavy metal pollution will be more complex than expected.
基金Supported by the State Key Basic Research and Development Plan of China (Grant No. 2006CB101706)the National Natural Science Foundation of China (Grant Nos. 30270753 & 30370804)
文摘Metallothioneins (MTs) are a group of low molecular mass and cysteine-rich proteins that can chelate heavy-metal ions. In this paper,Northern blot analysis was used to investigate the influence of lead stress on the expression patterns of 10 rice class I MT genes (OsMT-Is) in rice seedlings. With the ex-ception of OsMT-I-3b,the data demonstrate dynamic changes of 9 OsMT-I transcripts in response to Pb2+ treatment in rice seedling roots. Of these genes,transcription of OsMT-I-1a,OsMT-I-1b,OsMT-I-2c,OsMT-I-4a,OsMT-I-4b and OsMT-I-4c increased significantly,while transcription of OsMT-I-2a and OsMT-I-3a increased marginally. In contrast,the expression of OsMT-I-2b was inhibited. Pb2+ induced the expression of 6 OsMT-I genes in seedling shoots,but had no obvious effects on the expression of OsMT-I-1a,OsMT-I-1b,OsMT-I-4a and OsMT-I-4b. All the 10 OsMT-Is had enhanced lead tolerance when heterologously expressed in lead-sensitive yeast mutant cells. These results provide an expression profile of the rice MT gene family in response to Pb2+ stress in rice seedlings and demonstrate in-creased lead tolerance in sensitive yeast mutant cells expressing OsMT-Is. This study lays a foundation for further analysis of the role of the rice MT gene family in respond to Pb2+ stress.
基金This work was supported by the National 973 Program of China 2002 CB 512905
文摘Objective To study the gene expression of metallothionein 1 （MT-1） isoforms in human peripheral blood lymphocytes （HPBLs）. Methods The expression of mRNA representing the seven active MT-I genes was determined in HPBLs by quantitative RT-PCR before and after exposure to cadmium. Results Basal expressions of MT-IX, and MT-1A in HPBLs were similar to expression of housekeeping gene. In contrast, the basal gene expressions of MT- 1 H, IF, 1E, and 1G were a little transcripts in human HPBLs. No signal was detected for MT-1B. There was a sex difference （P〈0.05）. in basal gene expression of MT-1E. The levels of gene expression of MT-1A, 1E, IF, 1G, 1H, and 1X increased, but the level of MT-1B did not increase after exposure to cadmium. Conclusions Gene expressions of MT-1 G, MT-1 H, MT-1 F, and MT-1X in HPBLs can be used as a potential biomarker of cadmium exposure.
基金Project supported in part by a grant-in-aid from Rockefeller Foundation, New York.
文摘I. INTRODUCTIONMetallothioneins(MT) are ubiquitously distributed in animal and plant kingdoms. They are cysteine-rich proteins that specifically bind heavy metal ions, such as cadmium, zinc, mercury and copper. The high expression of the MT gene could be induced by heavy metals in vitro and in vivo. The first transgenic mice obtained by Palmiter et al. in 1982 were introduced with an exogenous growth hormnoe gene
基金Project partially supported by the Rockefeller Foundation.
文摘1 Introduction Metallothioneins (MTs) are a family of low-molecular weight heavy metal binding proteins, unique in their high cystein content. MTs are ubiquitously distributed in the eukaryote from yeast to human. It is an experimental model emphasized during researching gene expression and regulation of animal cells. In order to provide inducible regulatory elements for transgenosis livestock, we cloned bovine MT genes. At least four members of bovine MT family have been discovered. In this note, one gene (bMTc) of
文摘From Tetrahymena thermophila （strain BF5）, the coding region of Cd-MT gene was cloned and sequenced. and identified as MTT1 isoform. A serial duplicate structure is discovered in its amino acid sequence, which separates the coding region into three parts （Part 1：7-61; Part 2：64-118; Part 3：122-162）. The alignments among them and comparison with the corresponding parts of MT1 isoform suggest that MT1 and MTT1 isoforms both come from the same ancient gene that is homologous to Part 1, and Cd-MTs of Tetrahymena are aroused by such ancient gene duplication. The prediction of secondary structures and the analysis of the disulfide-bonding state of cysteine show that there are a lot of differences between MT1 and MTT1 isoforms, which maybe relate to their function mechanism.
文摘金属硫蛋白(metallothionein,MT)MT3是人体中参与重金属解毒的主要蛋白,前期研究表明啤酒酵母(Saccharomyces c erevisiae)α因子信号肽(MF-α)介导重组蛋白EGFP分泌到植物体外。但是目前还没有研究报道转基因植物中过量表达分泌型MT3对植物重金属镉(Cd)的富集能力是否有影响。本研究通过人工方法合成MF-α信号肽、增强型绿色荧光蛋白(enhanced green fluorescent protein,EGFP)和MT3的融合基因MF-α-EGFP-MT3,构建该融合基因的植物表达载体pK-35S-MF-α-EGFP-MT3,转化野生型(WT)烟草和天竺葵获得转基因植物。通过电化学方法检测转基因植物MT3转录水平、转基因植物根系分泌液中EGFP-MT3蛋白的水平。用Cd溶液处理转基因植物,通过表型观察和电化学方法检测根、茎和叶中Cd的含量。结果表明,转基因烟草和天竺葵中都有MT3基因的转录;且根系分泌EGFP-MT3蛋白的量大约为0.45~0.68 mg·g-1(以鲜质量计)。100μmol·L-1的Cd溶液处理转基因烟草植株,表型变化分析发现转基因植株受损情况低于WT,近根部叶片叶绿素含量显著高于WT,说明EGFP-MT3的分泌可降低Cd的毒害作用。转基因烟草植株根、茎和叶片对Cd的富集量比WT高约40%。用50μmol·L-1的Cd溶液处理转基因天竺葵植株,结果表明转基因植株根对Cd的富集量比WT高约30%,茎对Cd的富集量比WT高约4倍。以上结果证明过量表达EGFP-MT3可以提高转基因烟草和天竺葵对Cd的富集能力,可能是EGFP-MT3分泌根系表面增加转基因植物根系对Cd的吸附作用,同时在转基因植物组织细胞内积累的EGFP-MT3也可增加植物组织对Cd的富集作用。
基金The Key Science and Technology Program of Shandong Province under contract No. 2012GHY11527Natural Science Foundation of Shandong Province under contract No. Q2007E02+1 种基金Specialized Research Fund for the Doctoral Program of Higher Education (New Teachers) under contract No. 20070423027the Public Science and Technology Research Funds Projects of Ocean, State Oceanic Administration of the People’s Republic of China under contract No. 201105021-8
文摘Zostera marina, a monocotyledonous angiosperm, is one of the most important seagrass species. To inves- tigate the salt-tolerance mechanism and discover salt-tolerant genes in Z. marina, a cDNA library was con- structed. Single-pass sequencing of the 5＇ ends of 4 081 clones yielded 4 002 high quality expressed sequence tags （ESTs）, which were assembled into 241 contigs and 1 673 singletons, representing 1 914 unigenes. The average length of the ESTs was 582 bp, with sizes ranging from 100-1 500 bp. Basic Local Alignment Search Tool （BLASTX） analysis revealed that 1 664 unigenes had significant homology to known genes in the Na- tional Center for Biotechnology Information （NCBI） non-redundant （nr） database （E-value≤5-10）. Among them, the two most abundant genes encoded metallothionein （157 ESTs） and chlorophyll a/b-binding pro- tein （38 ESTs）, accounting for 7.1% and 1.7% of the total ESTs, respectively. Using Kyoto Encyclopedia of Genes and Genomes （KEGG）, 1 462 unigenes were assigned to 1 161 pathways （E-value≤5-10）. A total of 938 unigenes were assigned Gene Ontology （GO） terms based on the GO hierarchy analysis, and InterProScan searches recognized 1 003 InterPro families. Three genes for metallothionein in Z. marina that belonged to Class II was identified. Results of this study will improve understanding of the molecular mechanisms of saline tolerance in Z. marina.
