Species in genus Nannochloropsis,especially N.oceanica and N.gaditana,have been evolving as the model microalgae for both application and theory studies.The position effect of genome integration,the carrying capabilit...Species in genus Nannochloropsis,especially N.oceanica and N.gaditana,have been evolving as the model microalgae for both application and theory studies.The position effect of genome integration,the carrying capability limitation of integrative vectors and the instability of non-integrative vectors have hindered Nannochloropsis genetic modification with concatenate genes and extremely long DNA fragments.The molecular tools including genetic transformation,homologous recombination,gene edition,gene stacking and episome vectors for transient gene expression and diverse reporters and selection markers have been rapidly developing in Nannochloropsis species.The construction of animal and plant artificial chromosomes with“top down”strategy has set fine examples for the construction of Nannochloropsis artificial chromosomes(NannoACs).It seems that the methods and materials to set the foundation for constructing NannoACs are at hands.In this review,we outlined the current status of transgenes in Nannochloropsis species,summarized the limitations of both integrative and non-integrative vectors,and proposed a tentative approach to construct NannoACs by doubling and stabilizing the genome first,and then truncating the natural chromosomes.NannoACs once constructed will facilitate transferring the desired traits and concatenate genes into Nannochloropsis genetic backgrounds,thus contributing towards its genetic improvement and synthetic biological studies.展开更多
Sperms from Pink salmon were subjected to incomplete irradiation by γ-ray to cause partial breakageof their chromosome. Normal eggs from masu salmon were fertilized by these damaged sperms andput under hydrostatic pr...Sperms from Pink salmon were subjected to incomplete irradiation by γ-ray to cause partial breakageof their chromosome. Normal eggs from masu salmon were fertilized by these damaged sperms andput under hydrostatic pressure to suppress the release of second polar bodies. The resultant eggscontained complete sets of genome from masu salmon and some chromosomes and chromosomefragments from pink salmon. Karyotype and isozyme of the embryos were analyzed. The resultsdemonstrate that the chromosomes from pink salmon showed genetic activities. Variations in hatchedindividuals were observed.展开更多
Multiple chromosomes in bacteria are designated as a larger primary chromosome (CI) and smaller accessory chromosomes (CII and CIII). Although previous studies examined multiple chromosomes in several bacterial specie...Multiple chromosomes in bacteria are designated as a larger primary chromosome (CI) and smaller accessory chromosomes (CII and CIII). Although previous studies examined multiple chromosomes in several bacterial species, the evolutionary mechanisms for the origin of CIIs still remain unclear. In this study, the four following hypotheses were tested. 1) CIIs exhibit lower sequence conservation and sequence divergence compared to their corresponding CIs across species of Proteobacteria. 2) The differential sequence divergence of CI and CII depends on pathogenic and non-pathogenic lifestyles. 3) CIIs harbor a higher level of horizontal gene transfers (HGTs) than CIs. 4) Orthologs located on CIIs experience less purifying selection than their corresponding orthologs on CIs. Results reveal a higher level of sequence conservation of CIs than the sequence conservation of CIIs. There is no significant difference in HGT estimates between CIs and CIIs. A majority of orthologous genes of CIs and CIIs experience purifying selection;however, genes on CIIs were significantly less constrained than the corresponding ones on CIs. This finding is true for both pathogenic and non-pathogenic bacteria, but the selective constraints for non-pathogenic bacteria are relatively less constrained. It was concluded that the differential selective constraint is a potent driving force for the rapid evolution of CII. Therefore, gene expression analysis at the transcriptome and proteome levels may shed light on the gene regulation mechanisms that might affect the sequence divergence between CI and CII.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
基金Supported by the National Key R&D Program of China(Nos.2018YFD0901506,2018YFD0900305)the Marine S&T Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology(Qingdao)(No.2018 SDKJ0406-3)。
文摘Species in genus Nannochloropsis,especially N.oceanica and N.gaditana,have been evolving as the model microalgae for both application and theory studies.The position effect of genome integration,the carrying capability limitation of integrative vectors and the instability of non-integrative vectors have hindered Nannochloropsis genetic modification with concatenate genes and extremely long DNA fragments.The molecular tools including genetic transformation,homologous recombination,gene edition,gene stacking and episome vectors for transient gene expression and diverse reporters and selection markers have been rapidly developing in Nannochloropsis species.The construction of animal and plant artificial chromosomes with“top down”strategy has set fine examples for the construction of Nannochloropsis artificial chromosomes(NannoACs).It seems that the methods and materials to set the foundation for constructing NannoACs are at hands.In this review,we outlined the current status of transgenes in Nannochloropsis species,summarized the limitations of both integrative and non-integrative vectors,and proposed a tentative approach to construct NannoACs by doubling and stabilizing the genome first,and then truncating the natural chromosomes.NannoACs once constructed will facilitate transferring the desired traits and concatenate genes into Nannochloropsis genetic backgrounds,thus contributing towards its genetic improvement and synthetic biological studies.
文摘Sperms from Pink salmon were subjected to incomplete irradiation by γ-ray to cause partial breakageof their chromosome. Normal eggs from masu salmon were fertilized by these damaged sperms andput under hydrostatic pressure to suppress the release of second polar bodies. The resultant eggscontained complete sets of genome from masu salmon and some chromosomes and chromosomefragments from pink salmon. Karyotype and isozyme of the embryos were analyzed. The resultsdemonstrate that the chromosomes from pink salmon showed genetic activities. Variations in hatchedindividuals were observed.
文摘Multiple chromosomes in bacteria are designated as a larger primary chromosome (CI) and smaller accessory chromosomes (CII and CIII). Although previous studies examined multiple chromosomes in several bacterial species, the evolutionary mechanisms for the origin of CIIs still remain unclear. In this study, the four following hypotheses were tested. 1) CIIs exhibit lower sequence conservation and sequence divergence compared to their corresponding CIs across species of Proteobacteria. 2) The differential sequence divergence of CI and CII depends on pathogenic and non-pathogenic lifestyles. 3) CIIs harbor a higher level of horizontal gene transfers (HGTs) than CIs. 4) Orthologs located on CIIs experience less purifying selection than their corresponding orthologs on CIs. Results reveal a higher level of sequence conservation of CIs than the sequence conservation of CIIs. There is no significant difference in HGT estimates between CIs and CIIs. A majority of orthologous genes of CIs and CIIs experience purifying selection;however, genes on CIIs were significantly less constrained than the corresponding ones on CIs. This finding is true for both pathogenic and non-pathogenic bacteria, but the selective constraints for non-pathogenic bacteria are relatively less constrained. It was concluded that the differential selective constraint is a potent driving force for the rapid evolution of CII. Therefore, gene expression analysis at the transcriptome and proteome levels may shed light on the gene regulation mechanisms that might affect the sequence divergence between CI and CII.
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.
