Generation of induced pluripotent stem （iPS） cells from somatic cells has been achieved successfully by simultaneous viral transduction of defined reprogramming transcription factors （TFs）. However, the process re...Generation of induced pluripotent stem （iPS） cells from somatic cells has been achieved successfully by simultaneous viral transduction of defined reprogramming transcription factors （TFs）. However, the process requires multiple viral vectors for gene delivery. As a result, generated iPS cells harbor numerous viral integration sites in their genomes. This can increase the probability of gene mutagenesis and genomic instability, and present significant barriers to both research and clinical application studies of iPS cells. In this paper, we present a simple lentivirus reprogramming system in which defined factors are fused in-frame into a single open reading frame （ORF） via self-cleaving 2A sequences. A GFP marker is placed downstream of the transgene to enable tracking of transgene expression. We demonstrate that this polycistronic expression system efficiently generates iPS cells. The generated iPS cells have normal karyotypes and are similar to mouse embryonic stem cells in morphology and gene expression. Moreover, they can differentiate into cell types of the three embryonic germ layers in both in vitro and in vivo assays. Remarkably, most of these iPS cells only harbor a single copy of viral vector. This system provides a valuable tool for generation of iPS cells, and our data suggest that the balance of expression of transduced reprogramming TFs in each cell is essential for the reprogramming process. More importantly, when delivered by non-integrating gene-delivery systems, this re-engineered single ORF will facilitate efficient generation of human iPS cells free of genetic modifications.展开更多
Objective: In order to elucidate the molecular mechanisms that might be responsible for hepatocarcinogenesis, we examined microsatellite instability (MSI), mismatch repair gene hMLH1 mutation and methylation in hepato...Objective: In order to elucidate the molecular mechanisms that might be responsible for hepatocarcinogenesis, we examined microsatellite instability (MSI), mismatch repair gene hMLH1 mutation and methylation in hepatocellular carcinoma. Methods: Fifty-two cases of surgically resected sporadic hepatocellular carcinoma (HCC) were studied. hMLH1 mutation was examined by two-dimensional electrophoresis and DNA sequencing; hMLH1 methylation was determined by methylation-specific PCR(MSP); and MSI at BAT26 was analyzed by PCR-based methods. Results: MSI at BAT26 was found in 3 of 52 cases (5.8%) of the tumors analyzed. No hMLH1 mutation or hypermethylation was found in these 52 cancerous tissues. No correlation existed between MSI and clinico-pathological characteristics of the patients. Conclusion: Our results suggest that MSI at BAT26 is rarely associated with carcinogenesis of chinese HCC. The genesis of sporadic HCC may occur in an alternative pathway that is probably different from MSI pathway.展开更多
The objectives of this research were to understand pattern of temporal （year to year） stability in oil palm genotypes and then identify weather variable（s） associated with temporal stability. Stability analysis wa...The objectives of this research were to understand pattern of temporal （year to year） stability in oil palm genotypes and then identify weather variable（s） associated with temporal stability. Stability analysis was performed using the GGE biplot method. The best genotype in one year was not same always in the other year due to changes in the weather conditions over the years. Test environment evaluation revealed that the year 2000 （Y00） was the best representative of the overall environments and most powerful to discriminate genotypes with superior mean yield and temporal stability. The relationship of the climatic factors on the basis of their joint contribution to the development of specific trait varied from the pattern observed when their roles on the same traits were individually assessed. Maximum relative humidity, sunshine and rainfall could help explain the yield fluctuation due to their contribution to the overall yield variation. However, genotypes GI0 and G2 which exhibited high mean performance and stability for BN would be beneficial to the oil palm growers in ensuring steady cash flow from regular bunch yield production.展开更多
Stability among 50 accessions of West African okra （Abelmoschus caillei） was assessed under three diverse ecological environments at Abeokuta, Ibadan and Mokwa in Nigeria during 2005 and 2006 cropping season. The ac...Stability among 50 accessions of West African okra （Abelmoschus caillei） was assessed under three diverse ecological environments at Abeokuta, Ibadan and Mokwa in Nigeria during 2005 and 2006 cropping season. The accessions were grown in a Randomized Complete Block Design with three replications; data were collected on 5-10 randomly selected plants from each plot. Only 20 accessions were subjected to stability analysis on the basis of yield across the three environments. The joint regression analysis, deviation means square were computed using Eberhart and Russell method and complemented with Francis and Kannenberg method. The regression coefficients of accessions mean yields on the environmental index resulted in regression coefficients ranging in values from 0.5549 to 1.6667. OAA/96/175-5328, NGAE-96-011 and NGAE-96-0060 were among the superior genotypes with high yield performance. The large variation in regression values indicated large differences in genotype response to different environments. It suggests that stability concept of Ebelhart and Russell could be modified to use any yield components that has strong correlation with yield for stability analysis. The two promising accessions ofA. caillei （NGAE-96-011 and NGAE-96-0060） needed to be further tested on farmers＇ field to obtain on-farm data, alter which it should be recommended for official registration and released by the National Committee on Naming, Registration and Release of Crop varieties in Nigeria.展开更多
文摘Generation of induced pluripotent stem （iPS） cells from somatic cells has been achieved successfully by simultaneous viral transduction of defined reprogramming transcription factors （TFs）. However, the process requires multiple viral vectors for gene delivery. As a result, generated iPS cells harbor numerous viral integration sites in their genomes. This can increase the probability of gene mutagenesis and genomic instability, and present significant barriers to both research and clinical application studies of iPS cells. In this paper, we present a simple lentivirus reprogramming system in which defined factors are fused in-frame into a single open reading frame （ORF） via self-cleaving 2A sequences. A GFP marker is placed downstream of the transgene to enable tracking of transgene expression. We demonstrate that this polycistronic expression system efficiently generates iPS cells. The generated iPS cells have normal karyotypes and are similar to mouse embryonic stem cells in morphology and gene expression. Moreover, they can differentiate into cell types of the three embryonic germ layers in both in vitro and in vivo assays. Remarkably, most of these iPS cells only harbor a single copy of viral vector. This system provides a valuable tool for generation of iPS cells, and our data suggest that the balance of expression of transduced reprogramming TFs in each cell is essential for the reprogramming process. More importantly, when delivered by non-integrating gene-delivery systems, this re-engineered single ORF will facilitate efficient generation of human iPS cells free of genetic modifications.
文摘Objective: In order to elucidate the molecular mechanisms that might be responsible for hepatocarcinogenesis, we examined microsatellite instability (MSI), mismatch repair gene hMLH1 mutation and methylation in hepatocellular carcinoma. Methods: Fifty-two cases of surgically resected sporadic hepatocellular carcinoma (HCC) were studied. hMLH1 mutation was examined by two-dimensional electrophoresis and DNA sequencing; hMLH1 methylation was determined by methylation-specific PCR(MSP); and MSI at BAT26 was analyzed by PCR-based methods. Results: MSI at BAT26 was found in 3 of 52 cases (5.8%) of the tumors analyzed. No hMLH1 mutation or hypermethylation was found in these 52 cancerous tissues. No correlation existed between MSI and clinico-pathological characteristics of the patients. Conclusion: Our results suggest that MSI at BAT26 is rarely associated with carcinogenesis of chinese HCC. The genesis of sporadic HCC may occur in an alternative pathway that is probably different from MSI pathway.
文摘The objectives of this research were to understand pattern of temporal （year to year） stability in oil palm genotypes and then identify weather variable（s） associated with temporal stability. Stability analysis was performed using the GGE biplot method. The best genotype in one year was not same always in the other year due to changes in the weather conditions over the years. Test environment evaluation revealed that the year 2000 （Y00） was the best representative of the overall environments and most powerful to discriminate genotypes with superior mean yield and temporal stability. The relationship of the climatic factors on the basis of their joint contribution to the development of specific trait varied from the pattern observed when their roles on the same traits were individually assessed. Maximum relative humidity, sunshine and rainfall could help explain the yield fluctuation due to their contribution to the overall yield variation. However, genotypes GI0 and G2 which exhibited high mean performance and stability for BN would be beneficial to the oil palm growers in ensuring steady cash flow from regular bunch yield production.
文摘Stability among 50 accessions of West African okra （Abelmoschus caillei） was assessed under three diverse ecological environments at Abeokuta, Ibadan and Mokwa in Nigeria during 2005 and 2006 cropping season. The accessions were grown in a Randomized Complete Block Design with three replications; data were collected on 5-10 randomly selected plants from each plot. Only 20 accessions were subjected to stability analysis on the basis of yield across the three environments. The joint regression analysis, deviation means square were computed using Eberhart and Russell method and complemented with Francis and Kannenberg method. The regression coefficients of accessions mean yields on the environmental index resulted in regression coefficients ranging in values from 0.5549 to 1.6667. OAA/96/175-5328, NGAE-96-011 and NGAE-96-0060 were among the superior genotypes with high yield performance. The large variation in regression values indicated large differences in genotype response to different environments. It suggests that stability concept of Ebelhart and Russell could be modified to use any yield components that has strong correlation with yield for stability analysis. The two promising accessions ofA. caillei （NGAE-96-011 and NGAE-96-0060） needed to be further tested on farmers＇ field to obtain on-farm data, alter which it should be recommended for official registration and released by the National Committee on Naming, Registration and Release of Crop varieties in Nigeria.
