The nuclei and chromosomes were isolated from plasmodia of Physarum polycephalum. The nuclear matrir and chromosome scaffold were obtained after the DNA and most of the proteins were extracted with DNase I and 2 M NaC...The nuclei and chromosomes were isolated from plasmodia of Physarum polycephalum. The nuclear matrir and chromosome scaffold were obtained after the DNA and most of the proteins were extracted with DNase I and 2 M NaCl. SDS-PAGE analyses revealed that the nuclear matrir and chromosome scaffold contained a 37 kD polypeptide which is equivalent to tropomyosin in molecular weight. Immunofluorescence observations upon slide preparations labeled with anti-tropomyosin antibody showed that the nuclear matrix and chromosome scaffold emanated bright fluorescence, suggesting the presence of the antigen in them.Immunodotting results confirmed the presence of tropomyosin in the nuclear matrix and chromosome scaffold. Immunoelectron microscopic obserwtions further demonstrated that tropomyosin was dispersively distributed in the interphase nuclei and metaphase chromosomes.展开更多
Dinoflagellate is one of the primitive eukaryotes, whose nucleus may represent one of the transition stages from prokaryotic nucleoid to typical eukaryotic nucleus. Using selective extraction together with embeddment ...Dinoflagellate is one of the primitive eukaryotes, whose nucleus may represent one of the transition stages from prokaryotic nucleoid to typical eukaryotic nucleus. Using selective extraction together with embeddment - free section and whole mount electron microscopy, a delicate nuclear matrix filament network was shown, for the first time, in dinoflagellate Crypthecodinium cohnii nucleus. Chromosome residues are connected with nuclear matrix filaments to form a complete network spreading over the nucleus. Moreover, we demonstrated that the dinoflagellate chromosome retains a protein scaffold after the depletion of DNA and soluble proteins. This scaffold preserves the characteristic morphology of the chromosome. Two dimensional elec-trophoreses indicated that the nuclear matrix and chromosome scaffold are mainly composed of acidic proteins. Our results demonstrated that a framework similar to the nuclear matrix and chromosome scaffold in mammalian cells appears in this primitive eukaryote,suggesting that these structures may have been originated from the early stages of eukaryote evolution.展开更多
Incubation of dinoflagellate Crythecodinium cohnii chromosomes in cytoplasmic extracts of unfertilized Xenopus laevis eggs resulted in chromosomes decondensation and recondensation, nuclear envelope assembly, and nucl...Incubation of dinoflagellate Crythecodinium cohnii chromosomes in cytoplasmic extracts of unfertilized Xenopus laevis eggs resulted in chromosomes decondensation and recondensation, nuclear envelope assembly, and nuclear reconstitution.Dinoflagellate Crythecodinium cohnii is a kind of primitive eukaryote which possesses numerous permanently condensed chromosomes and discontinuous double-layered nuclear membrane throughout the cell cycle. The assembled nuclei, being surrounded by a continuous double membrane containing nuclear pores and the uniformly dispersed chromatin fibers are morphologically distinguishable from that of Dinoflagellate Crythecodinium cohnii. However, incubation of dinoflagellate Crythecodinium cohnii chromosomes in the extracts from dinoflagellate Crythecodinillm cohnii cells does not induce nuclear reconstitution.展开更多
Objective To analyze the blastocyst formation and chromosome statuses of reconstructed embryos derived from human-goat interspecies somatic cell nuclear transfer （iSCNT）, exploring the development retardant factors....Objective To analyze the blastocyst formation and chromosome statuses of reconstructed embryos derived from human-goat interspecies somatic cell nuclear transfer （iSCNT）, exploring the development retardant factors. Methods Human specific point probes cep2, cep6, tel2 and 13q14.2, 21q22.13 combining fluorescence in-situ hybridization （FISH） technology were used to test trophectoderm cells of blastocyst and blastomeres of development arrest nuclear transfer （NT） embryos. Results A total of 209 reconstructed embryos were recovered, and the rate of blastocyst formation was 3.8% （8/209）. FISH signals showed that chromosomal abnormalities were present in 2 blastocysts （2/8） and 146 development arrest embryos （146/201）. Conclusion The rate of blastocyst formation is low, and reconstituted embryos of development arrest showed extensive chromosome abnormalities, suggesting that a chromosomal mechanism may underlie their developmental arrest.展开更多
Nuclear matrix is a delicate proteineous network in eukaryote nucleus, and its functional diversity is becoming increasingly apparent.It is generally acknowledged that nuclear matrix,being a morphological and biochemi...Nuclear matrix is a delicate proteineous network in eukaryote nucleus, and its functional diversity is becoming increasingly apparent.It is generally acknowledged that nuclear matrix,being a morphological and biochemical complex molecular展开更多
Meiosis is a specialized eukaryotic cell division, in which diploid cells undergo a single round of DNA replication and two rounds of nuclear division to produce haploid gametes. In most eukaryotes, the core events of...Meiosis is a specialized eukaryotic cell division, in which diploid cells undergo a single round of DNA replication and two rounds of nuclear division to produce haploid gametes. In most eukaryotes, the core events of meiotic prophase I are chromosomal pairing,synapsis and recombination. To ensure accurate chromosomal segregation, homologs have to identify and align along each other at the onset of meiosis. Although much progress has been made in elucidating meiotic processes, information on the mechanisms underlying chromosome pairing is limited in contrast to the meiotic recombination and synapsis events. Recent research in many organisms indicated that centromere interactions during early meiotic prophase facilitate homologous chromosome pairing, and functional centromere is a prerequisite for centromere pairing such as in maize. Here, we summarize the recent achievements of chromosome pairing research on plants and other organisms, and outline centromere interactions, nuclear chromosome orientation,and meiotic cohesin, as main determinants of chromosome pairing in early meiotic prophase.展开更多
Using Electron Spectroscopic Imaging (ESI), we visualized the in situ binding of nucleic acids to nuclear matrix and 3H-thymidine incorporation which indicates that a small partial DNA bound to nuclear matrix tightly....Using Electron Spectroscopic Imaging (ESI), we visualized the in situ binding of nucleic acids to nuclear matrix and 3H-thymidine incorporation which indicates that a small partial DNA bound to nuclear matrix tightly. Furthermore we found that chromosomal telomere DNA could bind to nuclear matrix specifically by the dot and Southern hybridization. The result of the Southwestern blot suggests that telomere DNA has high affinity to lamin B, vimentin and some nuclear matrix proteins. Therefore, the nuclear matrix and lamina of HeLa cell are possibly associated with spatial organization and action of chromosome.展开更多
Telomeres,the natural termini of chromosomes in eukaryotes,play a very importantrole in stability and complete replication of chromosomes.Previous observations suggestthat chromosomes have non-random distribution in i...Telomeres,the natural termini of chromosomes in eukaryotes,play a very importantrole in stability and complete replication of chromosomes.Previous observations suggestthat chromosomes have non-random distribution in interphase nuclei,and their telomeresusually exist under nuclear envelope.However,no direct evidence available supportssuch an idea.In recent years telomeric DNA sequences of many organizations have beenfound based on the great progress of telomeric study.Therefore we can study展开更多
Somatic cloning has been succeeded in some species, but the cloning efficiency is very low, which limits the application of the technique in many areas of research and biotechnology. The cloning of mammals by somatic ...Somatic cloning has been succeeded in some species, but the cloning efficiency is very low, which limits the application of the technique in many areas of research and biotechnology. The cloning of mammals by somatic cell nuclear transfer (NT) requires epigenetic reprogramming of the differentiated state of donor cell to a totipotent, embry-onic ground state. Accumulating evidence indicates that in-complete or inappropriate epigenetic reprogramming of do-nor nuclei is likely to be the primary cause of failures in nu-clear transfer. This review summarizes the roles of various epigenetic mechanisms, including DNA methylation, histone acetylation, imprinting, X-chromosome inactivation, te-lomere maintenance and expressions of development-related genes on somatic nuclear transfer.展开更多
文摘The nuclei and chromosomes were isolated from plasmodia of Physarum polycephalum. The nuclear matrir and chromosome scaffold were obtained after the DNA and most of the proteins were extracted with DNase I and 2 M NaCl. SDS-PAGE analyses revealed that the nuclear matrir and chromosome scaffold contained a 37 kD polypeptide which is equivalent to tropomyosin in molecular weight. Immunofluorescence observations upon slide preparations labeled with anti-tropomyosin antibody showed that the nuclear matrix and chromosome scaffold emanated bright fluorescence, suggesting the presence of the antigen in them.Immunodotting results confirmed the presence of tropomyosin in the nuclear matrix and chromosome scaffold. Immunoelectron microscopic obserwtions further demonstrated that tropomyosin was dispersively distributed in the interphase nuclei and metaphase chromosomes.
文摘Dinoflagellate is one of the primitive eukaryotes, whose nucleus may represent one of the transition stages from prokaryotic nucleoid to typical eukaryotic nucleus. Using selective extraction together with embeddment - free section and whole mount electron microscopy, a delicate nuclear matrix filament network was shown, for the first time, in dinoflagellate Crypthecodinium cohnii nucleus. Chromosome residues are connected with nuclear matrix filaments to form a complete network spreading over the nucleus. Moreover, we demonstrated that the dinoflagellate chromosome retains a protein scaffold after the depletion of DNA and soluble proteins. This scaffold preserves the characteristic morphology of the chromosome. Two dimensional elec-trophoreses indicated that the nuclear matrix and chromosome scaffold are mainly composed of acidic proteins. Our results demonstrated that a framework similar to the nuclear matrix and chromosome scaffold in mammalian cells appears in this primitive eukaryote,suggesting that these structures may have been originated from the early stages of eukaryote evolution.
文摘Incubation of dinoflagellate Crythecodinium cohnii chromosomes in cytoplasmic extracts of unfertilized Xenopus laevis eggs resulted in chromosomes decondensation and recondensation, nuclear envelope assembly, and nuclear reconstitution.Dinoflagellate Crythecodinium cohnii is a kind of primitive eukaryote which possesses numerous permanently condensed chromosomes and discontinuous double-layered nuclear membrane throughout the cell cycle. The assembled nuclei, being surrounded by a continuous double membrane containing nuclear pores and the uniformly dispersed chromatin fibers are morphologically distinguishable from that of Dinoflagellate Crythecodinium cohnii. However, incubation of dinoflagellate Crythecodinium cohnii chromosomes in the extracts from dinoflagellate Crythecodinillm cohnii cells does not induce nuclear reconstitution.
基金supported by Grants from Special Fund for Excellent Young University teachers in Shanghai 2012Shanghai Science and Technology Developmental Foundations (Grant number: 09ZR1419000)
文摘Objective To analyze the blastocyst formation and chromosome statuses of reconstructed embryos derived from human-goat interspecies somatic cell nuclear transfer （iSCNT）, exploring the development retardant factors. Methods Human specific point probes cep2, cep6, tel2 and 13q14.2, 21q22.13 combining fluorescence in-situ hybridization （FISH） technology were used to test trophectoderm cells of blastocyst and blastomeres of development arrest nuclear transfer （NT） embryos. Results A total of 209 reconstructed embryos were recovered, and the rate of blastocyst formation was 3.8% （8/209）. FISH signals showed that chromosomal abnormalities were present in 2 blastocysts （2/8） and 146 development arrest embryos （146/201）. Conclusion The rate of blastocyst formation is low, and reconstituted embryos of development arrest showed extensive chromosome abnormalities, suggesting that a chromosomal mechanism may underlie their developmental arrest.
文摘Nuclear matrix is a delicate proteineous network in eukaryote nucleus, and its functional diversity is becoming increasingly apparent.It is generally acknowledged that nuclear matrix,being a morphological and biochemical complex molecular
基金supported by the National Natural Science Foundation of China(31600994.31630049)
文摘Meiosis is a specialized eukaryotic cell division, in which diploid cells undergo a single round of DNA replication and two rounds of nuclear division to produce haploid gametes. In most eukaryotes, the core events of meiotic prophase I are chromosomal pairing,synapsis and recombination. To ensure accurate chromosomal segregation, homologs have to identify and align along each other at the onset of meiosis. Although much progress has been made in elucidating meiotic processes, information on the mechanisms underlying chromosome pairing is limited in contrast to the meiotic recombination and synapsis events. Recent research in many organisms indicated that centromere interactions during early meiotic prophase facilitate homologous chromosome pairing, and functional centromere is a prerequisite for centromere pairing such as in maize. Here, we summarize the recent achievements of chromosome pairing research on plants and other organisms, and outline centromere interactions, nuclear chromosome orientation,and meiotic cohesin, as main determinants of chromosome pairing in early meiotic prophase.
文摘Using Electron Spectroscopic Imaging (ESI), we visualized the in situ binding of nucleic acids to nuclear matrix and 3H-thymidine incorporation which indicates that a small partial DNA bound to nuclear matrix tightly. Furthermore we found that chromosomal telomere DNA could bind to nuclear matrix specifically by the dot and Southern hybridization. The result of the Southwestern blot suggests that telomere DNA has high affinity to lamin B, vimentin and some nuclear matrix proteins. Therefore, the nuclear matrix and lamina of HeLa cell are possibly associated with spatial organization and action of chromosome.
文摘Telomeres,the natural termini of chromosomes in eukaryotes,play a very importantrole in stability and complete replication of chromosomes.Previous observations suggestthat chromosomes have non-random distribution in interphase nuclei,and their telomeresusually exist under nuclear envelope.However,no direct evidence available supportssuch an idea.In recent years telomeric DNA sequences of many organizations have beenfound based on the great progress of telomeric study.Therefore we can study
文摘Somatic cloning has been succeeded in some species, but the cloning efficiency is very low, which limits the application of the technique in many areas of research and biotechnology. The cloning of mammals by somatic cell nuclear transfer (NT) requires epigenetic reprogramming of the differentiated state of donor cell to a totipotent, embry-onic ground state. Accumulating evidence indicates that in-complete or inappropriate epigenetic reprogramming of do-nor nuclei is likely to be the primary cause of failures in nu-clear transfer. This review summarizes the roles of various epigenetic mechanisms, including DNA methylation, histone acetylation, imprinting, X-chromosome inactivation, te-lomere maintenance and expressions of development-related genes on somatic nuclear transfer.
