Most current knowledge about DNA polymerase zeta （pol ζ） comes from studies of the enzyme in the budding yeast Saccharomyces cerevisiae, where pol ζ consists of a complex of the catalytic subunit Rev3 with Rev7, w...Most current knowledge about DNA polymerase zeta （pol ζ） comes from studies of the enzyme in the budding yeast Saccharomyces cerevisiae, where pol ζ consists of a complex of the catalytic subunit Rev3 with Rev7, which associates with Revl. Most spontaneous and induced mutagenesis in yeast is dependent on these gene products, and yeast pol can mediate translesion DNA synthesis past some adducts in DNA templates. Study of the homologous gene products in higher eukaryotes is in a relatively early stage, but additional functions for the eukaryotic proteins are already apparent. Suppression of vertebrate REV3L function not only reduces induced point mutagenesis but also causes larger-scale genome instability by raising the frequency of spontaneous chromosome translocations. Disruption of Rev3L function is tolerated in Drosophila, Arabidopsis, and in vertebrate cell lines under some conditions, but is incompatible with mouse embryonic development. Functions for REV3L and REV7（MAD2B） in higher eukaryotes have been suggested not only in translesion DNA synthesis but also in some forms of homologous recombination, repair of interstrand DNA crosslinks, somatic hypermutation of immunoglobulin genes and cell-cycle control. This review discusses recent developments in these areas.展开更多
The term epigenetics refers to heritable changes not encoded by DNA. The organization of DNA into chromatin fibers affects gene expression in a heritable manner and is therefore one mechanism of epigenetic inheritance...The term epigenetics refers to heritable changes not encoded by DNA. The organization of DNA into chromatin fibers affects gene expression in a heritable manner and is therefore one mechanism of epigenetic inheritance. Large parts of eukaryotic genomes consist of constitutively highly condensed heterochromatin, important for maintaining genome integrity but also for silencing of genes within. Small RNA, together with factors typically associated with RNA interference （RNAi） targets homologous DNA sequences and recruits factors that modify the chromatin, com- monly resulting in formation of heterochromatin and silencing of target genes. The scope of this review is to provide an overview of the roles of small RNA and the RNAi components, Dicer, Argonaute and RNA dependent polymerases in epigenetic inheritance via heterochromatin formation, exemplified with pathways from unicellular eukaryotes, plants and animals.展开更多
The nuclear matrix of diplomonad Giardia lamblia was detected for the first time with DGD embedmentsectioning- embedment free electron microscopy after a series of specific extractions. The result showed that archaezo...The nuclear matrix of diplomonad Giardia lamblia was detected for the first time with DGD embedmentsectioning- embedment free electron microscopy after a series of specific extractions. The result showed that archaezoa Giardia lamblia already possessed nuclear matrix within its two nuclei. The finest fibrils of the nuclear matrix of Giardia lamblia were measured to be about 11 to 13 nm in thickness. However, the nuclear lamina and nucleolus have never been observed. These results seem to suggest that nuclear matrix is an indispensable intranuclear structural component even in the primitive nucleus.展开更多
Objective： To facilitate manipulation of gene expression in different host cells, we used pEGFP-N1 as backbone to construct a versatile vector that can drive foreign gene expression in prokaryotic and eukaryotic cell...Objective： To facilitate manipulation of gene expression in different host cells, we used pEGFP-N1 as backbone to construct a versatile vector that can drive foreign gene expression in prokaryotic and eukaryotic cells. Methods： A cloning and expression vector, pEGFP-NI-lac, was constructed by inserting the prokaryotic lac promoter of pUC 19 into the eukaryotic expression vector, pEGFP-N1, between the eukaryotic PCMV promoter and enhanced green fluorescent protein （EGFP） open reading frames. To assess the function of pEGFP-NI-lac, the nucleotide sequence encoding the hepatitis C virus （HCV） core protein was cloned into the multiple cloning sites. Western blotting analysis was used to detect the expression of the HCV core protein in Escherichia coli DH5a and HepG2 cells. Results： Restriction enzyme digestion and sequence analysis indicated that pEGFP-NI-lac was successfully constructed and the HCV core gene was cloned into this vector. The Western blotting results showed that pEGFP-NI-lac promoted expression of HCV core gene in prokaryotic E. coli DH5a and eukaryotic HepG2 cells. Conclusion： The pEGFP-NI-lac vector has been successfully constructed and functions in both prokaryotic and eukaryotic cells. The EGFP reporter can be used as an insert-inactivation marker for clone selection or as an expression tag. This vector can be used for cloning and expression of genes in both prokaryotic and eukaryotic cells, making gene cloning, expression and functional studies convenient as well as time- and labor-efficient展开更多
In eukaryote, nuclear structure is a key component forthe functions of eukaryotic cells. More and more evidencesshow that the nuclear structure plays important role in re-gulating DNA replication. The nuclear structur...In eukaryote, nuclear structure is a key component forthe functions of eukaryotic cells. More and more evidencesshow that the nuclear structure plays important role in re-gulating DNA replication. The nuclear structure providesa physical barrier for the replication licensing, participatesin the decision where DNA replication initiates, and orga-nizes replication proteins as replication factory for DNAreplication. Through these works, new concepts on theregulation of DNA replication have emerged, which willbe discussed in this minireview.展开更多
高迁移率族蛋白1（high mobility group box-1protein,HMGB1）是一个丰富的DNA结合蛋白,通常驻留在细胞核中,是真核细胞核内的非组蛋白染色质结合蛋白,在维持核小体结构的稳定和DNA重组、复制、修复及基因转录中发挥着重要作用[1]。作...高迁移率族蛋白1（high mobility group box-1protein,HMGB1）是一个丰富的DNA结合蛋白,通常驻留在细胞核中,是真核细胞核内的非组蛋白染色质结合蛋白,在维持核小体结构的稳定和DNA重组、复制、修复及基因转录中发挥着重要作用[1]。作为一种新的潜在晚期炎症介质,HMGB1参与了脓毒症发生的病理生理过程并起着重要作用。血管内皮细胞不仅是脓毒症受损的靶细胞,展开更多
DNA damage is a relatively common event in eukaryotic cell and may lead to genetic mutation and even cancer. DNA damage induces cellular responses that enable the cell either to repair the damaged DNA or cope with the...DNA damage is a relatively common event in eukaryotic cell and may lead to genetic mutation and even cancer. DNA damage induces cellular responses that enable the cell either to repair the damaged DNA or cope with the damage in an appropriate way. Histone proteins are also the fundamental building blocks of eukaryotic chromatin besides DNA, and many types of post-translational modifications often occur on tails of histones. Although the function of these modifications has remained elusive, there is ever-growing studies suggest that histone modifications play vital roles in several chromatin-based processes, such as DNA damage response. In this review, we will discuss the main histone modifications, and their functions in DNA damage response.展开更多
文摘Most current knowledge about DNA polymerase zeta （pol ζ） comes from studies of the enzyme in the budding yeast Saccharomyces cerevisiae, where pol ζ consists of a complex of the catalytic subunit Rev3 with Rev7, which associates with Revl. Most spontaneous and induced mutagenesis in yeast is dependent on these gene products, and yeast pol can mediate translesion DNA synthesis past some adducts in DNA templates. Study of the homologous gene products in higher eukaryotes is in a relatively early stage, but additional functions for the eukaryotic proteins are already apparent. Suppression of vertebrate REV3L function not only reduces induced point mutagenesis but also causes larger-scale genome instability by raising the frequency of spontaneous chromosome translocations. Disruption of Rev3L function is tolerated in Drosophila, Arabidopsis, and in vertebrate cell lines under some conditions, but is incompatible with mouse embryonic development. Functions for REV3L and REV7（MAD2B） in higher eukaryotes have been suggested not only in translesion DNA synthesis but also in some forms of homologous recombination, repair of interstrand DNA crosslinks, somatic hypermutation of immunoglobulin genes and cell-cycle control. This review discusses recent developments in these areas.
文摘The term epigenetics refers to heritable changes not encoded by DNA. The organization of DNA into chromatin fibers affects gene expression in a heritable manner and is therefore one mechanism of epigenetic inheritance. Large parts of eukaryotic genomes consist of constitutively highly condensed heterochromatin, important for maintaining genome integrity but also for silencing of genes within. Small RNA, together with factors typically associated with RNA interference （RNAi） targets homologous DNA sequences and recruits factors that modify the chromatin, com- monly resulting in formation of heterochromatin and silencing of target genes. The scope of this review is to provide an overview of the roles of small RNA and the RNAi components, Dicer, Argonaute and RNA dependent polymerases in epigenetic inheritance via heterochromatin formation, exemplified with pathways from unicellular eukaryotes, plants and animals.
文摘The nuclear matrix of diplomonad Giardia lamblia was detected for the first time with DGD embedmentsectioning- embedment free electron microscopy after a series of specific extractions. The result showed that archaezoa Giardia lamblia already possessed nuclear matrix within its two nuclei. The finest fibrils of the nuclear matrix of Giardia lamblia were measured to be about 11 to 13 nm in thickness. However, the nuclear lamina and nucleolus have never been observed. These results seem to suggest that nuclear matrix is an indispensable intranuclear structural component even in the primitive nucleus.
基金Supported by the National High Technology Research and Development Program of China (863 Program, 2009AA02Z111)the National Natural Science Foundation of China (30872223)the Funds of the State Key Laboratory of Pathogen and Biosecurity
文摘Objective： To facilitate manipulation of gene expression in different host cells, we used pEGFP-N1 as backbone to construct a versatile vector that can drive foreign gene expression in prokaryotic and eukaryotic cells. Methods： A cloning and expression vector, pEGFP-NI-lac, was constructed by inserting the prokaryotic lac promoter of pUC 19 into the eukaryotic expression vector, pEGFP-N1, between the eukaryotic PCMV promoter and enhanced green fluorescent protein （EGFP） open reading frames. To assess the function of pEGFP-NI-lac, the nucleotide sequence encoding the hepatitis C virus （HCV） core protein was cloned into the multiple cloning sites. Western blotting analysis was used to detect the expression of the HCV core protein in Escherichia coli DH5a and HepG2 cells. Results： Restriction enzyme digestion and sequence analysis indicated that pEGFP-NI-lac was successfully constructed and the HCV core gene was cloned into this vector. The Western blotting results showed that pEGFP-NI-lac promoted expression of HCV core gene in prokaryotic E. coli DH5a and eukaryotic HepG2 cells. Conclusion： The pEGFP-NI-lac vector has been successfully constructed and functions in both prokaryotic and eukaryotic cells. The EGFP reporter can be used as an insert-inactivation marker for clone selection or as an expression tag. This vector can be used for cloning and expression of genes in both prokaryotic and eukaryotic cells, making gene cloning, expression and functional studies convenient as well as time- and labor-efficient
文摘In eukaryote, nuclear structure is a key component forthe functions of eukaryotic cells. More and more evidencesshow that the nuclear structure plays important role in re-gulating DNA replication. The nuclear structure providesa physical barrier for the replication licensing, participatesin the decision where DNA replication initiates, and orga-nizes replication proteins as replication factory for DNAreplication. Through these works, new concepts on theregulation of DNA replication have emerged, which willbe discussed in this minireview.
文摘高迁移率族蛋白1（high mobility group box-1protein,HMGB1）是一个丰富的DNA结合蛋白,通常驻留在细胞核中,是真核细胞核内的非组蛋白染色质结合蛋白,在维持核小体结构的稳定和DNA重组、复制、修复及基因转录中发挥着重要作用[1]。作为一种新的潜在晚期炎症介质,HMGB1参与了脓毒症发生的病理生理过程并起着重要作用。血管内皮细胞不仅是脓毒症受损的靶细胞,
基金supported by the National Natural Science Foundation of China(8132100391319302+3 种基金31070691)Ministry of Science and Technology of China(2011CB504200)Ministry of Education of China(111 project)Peking University-Tsinghua University Center for Life Science
文摘DNA damage is a relatively common event in eukaryotic cell and may lead to genetic mutation and even cancer. DNA damage induces cellular responses that enable the cell either to repair the damaged DNA or cope with the damage in an appropriate way. Histone proteins are also the fundamental building blocks of eukaryotic chromatin besides DNA, and many types of post-translational modifications often occur on tails of histones. Although the function of these modifications has remained elusive, there is ever-growing studies suggest that histone modifications play vital roles in several chromatin-based processes, such as DNA damage response. In this review, we will discuss the main histone modifications, and their functions in DNA damage response.
