目的研究HMG20A在肝细胞癌(hepatocellular carcinoma,HCC)发生发展和转移中的功能与机制。方法在不同转移能力和遗传背景的肝癌细胞Huh7和HCCLM3中分别构建HMG20A过表达和敲低稳定株,通过实时定量PCR(real time quantitative PCR,qPCR...目的研究HMG20A在肝细胞癌(hepatocellular carcinoma,HCC)发生发展和转移中的功能与机制。方法在不同转移能力和遗传背景的肝癌细胞Huh7和HCCLM3中分别构建HMG20A过表达和敲低稳定株,通过实时定量PCR(real time quantitative PCR,qPCR)验证过表达和敲低该基因的效果。用CCK8试剂盒检测HMG20A对肝癌细胞增殖能力的影响,利用Transwell小室分析HMG20A调控肝癌细胞转移的能力。借助Western blot和qPCR分析HMG20A调控肝癌增殖和转移的机制。结果体外实验表明,HMG20A能够促进肝癌细胞的体外增殖和迁移,显著上调促分裂原活化蛋白激酶(mitogen-activated protein kinase,MAPK)通路中p38(p38 MAPK)、细胞外调节蛋白激酶(extracellular regulated protein kinase,ERK)的活性和表达水平,同时上皮间充质转化(epithelial-mesenchymal transition,EMT)的标志物Vimentin、抗平滑肌抗体(anti-smooth muscle antibody,alpha-SMA)、N-cadherin受到显著的正调控,E-cadherin受到显著负调控。结论 HMG20A可能通过促进EMT进程和MAPK通路促进肝癌细胞的体外增殖与迁移。展开更多
A novel p-channel selected n-channel divided bit-line NOR(PNOR) flash memory,which features low programming current,low power,high access current,and slight bit-line disturbance,is proposed.By using the source induced...A novel p-channel selected n-channel divided bit-line NOR(PNOR) flash memory,which features low programming current,low power,high access current,and slight bit-line disturbance,is proposed.By using the source induced band-to-band hot electron injection (SIBE) to perform programming and dividing the bit-line to the sub-bit-lines,the programming current and power can be reduced to 3.5μA and 16.5μW with the sub-bit-line width equaling to 128,and a read current of 60μA is obtained.Furthermore,the bit-line disturbance is also significantly alleviated.展开更多
An efficient in vitro protocol for mass production of shoot of Dahlia was developed by using node explant, various carbon sources such as sucrose, glucose, fructose and galactose. Agar concentrations and various growt...An efficient in vitro protocol for mass production of shoot of Dahlia was developed by using node explant, various carbon sources such as sucrose, glucose, fructose and galactose. Agar concentrations and various growth regulators on in vitro shoot multiplication of Dahlia were studied in the present investigation. The nodal explant from the gardens grown plant were used as testing plant material to develop an efficient protocol for mass propagation of exotic Dahlia to enhance their production for growers and the local markets. This study determined the effect of different carbon sucrose concentrations and gelling agent on in vitro propagation of Dahlia, different carbon sources （sucrose, glucose, fructose and galactose） were investigated, each sugar was added individually to the MS culture medium at the concentrations of 15, 30 and 45 g·L^-1, respectively. Culture medium of each treatment was supplemented with 1,5 mg·L^-1 BA ＋ 1.5 mg·L^-1Kin ＋ 7,0 g·L^-1 agar. The highest number of shoots （7.00）, number of leaves （11.50）, number of node （6.75） and shoot length （8.24 cm） was obtained on MS medium supplemented with 30 g·L^-1 glucose. The least number of shoots （3.38）, number of leaves （5.00）, number of node （3.13） and the least shoot length （2.96 cm） was obtained on 45 g·L^-1 galactose and the least shoot length （2.29 cm） was observed on MS medium with free carbon sources. While the medium with 30 g·L^-1 glucose and 8 g·L^-1 agar gave the highest number of shoots （7.13）, number of leaves （10.75）, number of node （7.13） and shoot length （8.18 cm）. However, the least number of shoots （1.50）, number of leaves （1.88）, number of node （1.63） and the least shoot length （1.26 cm） was obtained with 30 g·L^-1 galactose and 12 g·L^-1 agar. Rooting was readily achieved upon transferring the microshoots onto MS medium supplemented with 0.1 mg·L^-1 IBA, IAA and NAA and 30 g·L^-1 （w/v） different types of carbon sources. The percentage of rooting was less （71.88%） on MS medium containing IAA as compared with IBA or NAA. While the medium having 30 g·L^-1 glucose with 0.1 IBA or NAA mg·L^-1, give the highest percentage of root （100%）, and the highest number of root （3.88） and root length （3.56 cm） was obtained on MS medium containing 30 g·L^-1 glucose with 0.1 mg·L^-1 IBA. More than 98% of rooted plantlets were established in the greenhouse.展开更多
Mouse oocytes undergo polarization during meiotic maturation, and this polarization is essential for asymmetric cell divisions that maximize retention of maternal components required for early development. Without con...Mouse oocytes undergo polarization during meiotic maturation, and this polarization is essential for asymmetric cell divisions that maximize retention of maternal components required for early development. Without conventional centrosomes, the meiotic spindle has less focused poles and is barrel-shaped. The migration of meiotic spindles to the cortex is accompanied by a local reorganization and polarization of the cortex. LGN is a conserved protein involved in cell polarity and regulation of spindle organization. In the present study, we characterized the localization dynamics of LGN during mouse oocyte maturation and analyzed the effects of LGN upregulation and downregulation on meiotic spindle organization. At the germinal vesicle stage, LGN is distributed both cytoplasmically and at the cortex. During maturation, LGN localizes to the meiotic spindle apparatus and cortical LGN becomes less concentrated at the actin cap region. Excessive LGN induces meiotic spindle organization defects by elongating the spindle and enhancing pole focusing, whereas depletion of LGN by RNA interference results in meiotic spindle deformation and chromosome misalignment. Furthermore, the N-terminus of LGN has the ability of full-length LGN to regulate spindle organization, whereas the C-terminus of LGN controls cortical localization and polarization. Our results reveal that LGN is cortically polarized in mouse oocytes and is critical for meiotic spindle organization.展开更多
This research work aims to contribute in increasing the fruit set in citrus, given its importance in determining fruit yield. The authors evaluated the effects of phytohormones （auxins, gibberellins and cytokinins） ...This research work aims to contribute in increasing the fruit set in citrus, given its importance in determining fruit yield. The authors evaluated the effects of phytohormones （auxins, gibberellins and cytokinins） in the mooring and features of orange fruit in cultivars Washington navel and Thomson （Citrus sinensis （L.） Osb.）, The experiment was established in a split plot randomized complete block design with five treatments and four replications. Flower tissue samples were stored in liquid N until the extraction of gibberellins and the identification and quantification of GA3. The results showed statistically significant difference （P 〈 0.05） between treatments in the number of fruits retained 129 d after flowering and the percentage of final tie. GA3 content ranged, on a dry weight basis, from 1.66 mg＇g1 in the control to 20.79 mg.g-1 in the high dose. The mean dose （32.2 mg.L-1 auxins, gibberellins 32.2 mg L-1 and 83.2 mg.L-1 cytokinins） caused the largest increase in fruit set.展开更多
A simulation of the properties of the shifting scintillator neutron detector using 6LiF/ZnS(Ag) scintillation screens is performed.The simulation results show that the light attenuation length of standard BC704 scinti...A simulation of the properties of the shifting scintillator neutron detector using 6LiF/ZnS(Ag) scintillation screens is performed.The simulation results show that the light attenuation length of standard BC704 scintillator is about 0.65 mm.Its thermal neutron detection efficiency,gamma sensitivity and intrinsic spatial resolution can achieve around 50.0%,10 5and 0.18 mm(along X-axis) respectively.For the detector,air coupling position resolution is better than the silicone oil coupling.Some of the simulation results are compared with experimental results.They are in agreement.This work will be helpful for constructing neutron detector for high intensity powder diffractometer at Chinese spallation neutron source.展开更多
Rad51/RadA paralogs found in eukaryotes and euryarchaea play important roles during recombination and repair,and mutations in one of the human Rad51 paralogs,Rad51C,are associated with breast and ovarian cancers.The h...Rad51/RadA paralogs found in eukaryotes and euryarchaea play important roles during recombination and repair,and mutations in one of the human Rad51 paralogs,Rad51C,are associated with breast and ovarian cancers.The hyperthermophilic crenarchaeon Sulfolobus tokodaii encodes four putative RadA paralogs and studies on these proteins may assist in understanding the functions of human Rad51 paralogs.Here,we report the biochemical characterization of stRadC2,a S.tokodaii RadA paralog.Pull-down assays revealed that the protein was able to interact with the recombinase,RadA,and the Holliday junction endonuclease,Hjc.stRadC2 inhibited the strand exchange activity of RadA and facilitated Hjc-mediated Holliday junction DNA cleavage in vitro.RT-PCR analysis revealed that stRadC2 transcription was immediately reduced after UV irradiation,but was restored to normal levels at the late stages of DNA repair.Our results suggest that stRadC2 may act as an anti-recombination factor in DNA recombinational repair in S.tokodaii.展开更多
Meiosis comprises two rounds of nuclear division following a single phase of DNA replication, leading to the production of haploid gametes and is essential for sexual reproduction in eukaryotes. Unlike mitosis, meiosi...Meiosis comprises two rounds of nuclear division following a single phase of DNA replication, leading to the production of haploid gametes and is essential for sexual reproduction in eukaryotes. Unlike mitosis, meiosis involves homologous chromosome pairing, synapsis, and recombination during prophase I. Meiotic recombination not only ensures the accurate segregation of homologs, but also redistributes alleles among offspring. DNA synthesis is a critical process during meiotic recombination, but our understanding of the proteins that execute and regulate it is limited. This review summarizes the recent advances in defining the role of DNA synthesis in meiotic recombina- tion through analyses of DNA synthesis genes, with specific emphasis on DNA polymerases （e.g., Pole and PolS）, replication processivity factor RFC1 and translesion polymerases （e.g., Pol~）. We also present a new double strand break repair model for meiotic recombination, which includes lagging strand DNA synthesis and leading strand elongation. Finally, we propose that DNA synthesis is one of critical factors for discriminating meiotic recombination pathways and that this differentiation may be conserved among eukaryotes.展开更多
Meiotic recombination is a deeply conserved process within eukaryotes that has a profound effect on patterns of natural genetic variation. During meiosis homologous chromosomes pair and undergo DNA double strand break...Meiotic recombination is a deeply conserved process within eukaryotes that has a profound effect on patterns of natural genetic variation. During meiosis homologous chromosomes pair and undergo DNA double strand breaks generated by the Spo11 endonuclease. These breaks can be repaired as crossovers that result in reciprocal exchange between chromosomes. The frequency of recombination along chromosomes is highly variable, for example, crossovers are rarely observed in heterochromatin and the centromeric regions. Recent work in plants has shown that crossover hotspots occur in gene promoters and are associated with specific chromatin modifications, including H2 A.Z. Meiotic chromosomes are also organized in loop-base arrays connected to an underlying chromosome axis, which likely interacts with chromatin to organize patterns of recombination.Therefore, epigenetic information exerts a major influence on patterns of meiotic recombination along chromosomes, genetic variation within populations and evolution of plant genomes.展开更多
文摘A novel p-channel selected n-channel divided bit-line NOR(PNOR) flash memory,which features low programming current,low power,high access current,and slight bit-line disturbance,is proposed.By using the source induced band-to-band hot electron injection (SIBE) to perform programming and dividing the bit-line to the sub-bit-lines,the programming current and power can be reduced to 3.5μA and 16.5μW with the sub-bit-line width equaling to 128,and a read current of 60μA is obtained.Furthermore,the bit-line disturbance is also significantly alleviated.
文摘An efficient in vitro protocol for mass production of shoot of Dahlia was developed by using node explant, various carbon sources such as sucrose, glucose, fructose and galactose. Agar concentrations and various growth regulators on in vitro shoot multiplication of Dahlia were studied in the present investigation. The nodal explant from the gardens grown plant were used as testing plant material to develop an efficient protocol for mass propagation of exotic Dahlia to enhance their production for growers and the local markets. This study determined the effect of different carbon sucrose concentrations and gelling agent on in vitro propagation of Dahlia, different carbon sources （sucrose, glucose, fructose and galactose） were investigated, each sugar was added individually to the MS culture medium at the concentrations of 15, 30 and 45 g·L^-1, respectively. Culture medium of each treatment was supplemented with 1,5 mg·L^-1 BA ＋ 1.5 mg·L^-1Kin ＋ 7,0 g·L^-1 agar. The highest number of shoots （7.00）, number of leaves （11.50）, number of node （6.75） and shoot length （8.24 cm） was obtained on MS medium supplemented with 30 g·L^-1 glucose. The least number of shoots （3.38）, number of leaves （5.00）, number of node （3.13） and the least shoot length （2.96 cm） was obtained on 45 g·L^-1 galactose and the least shoot length （2.29 cm） was observed on MS medium with free carbon sources. While the medium with 30 g·L^-1 glucose and 8 g·L^-1 agar gave the highest number of shoots （7.13）, number of leaves （10.75）, number of node （7.13） and shoot length （8.18 cm）. However, the least number of shoots （1.50）, number of leaves （1.88）, number of node （1.63） and the least shoot length （1.26 cm） was obtained with 30 g·L^-1 galactose and 12 g·L^-1 agar. Rooting was readily achieved upon transferring the microshoots onto MS medium supplemented with 0.1 mg·L^-1 IBA, IAA and NAA and 30 g·L^-1 （w/v） different types of carbon sources. The percentage of rooting was less （71.88%） on MS medium containing IAA as compared with IBA or NAA. While the medium having 30 g·L^-1 glucose with 0.1 IBA or NAA mg·L^-1, give the highest percentage of root （100%）, and the highest number of root （3.88） and root length （3.56 cm） was obtained on MS medium containing 30 g·L^-1 glucose with 0.1 mg·L^-1 IBA. More than 98% of rooted plantlets were established in the greenhouse.
文摘Mouse oocytes undergo polarization during meiotic maturation, and this polarization is essential for asymmetric cell divisions that maximize retention of maternal components required for early development. Without conventional centrosomes, the meiotic spindle has less focused poles and is barrel-shaped. The migration of meiotic spindles to the cortex is accompanied by a local reorganization and polarization of the cortex. LGN is a conserved protein involved in cell polarity and regulation of spindle organization. In the present study, we characterized the localization dynamics of LGN during mouse oocyte maturation and analyzed the effects of LGN upregulation and downregulation on meiotic spindle organization. At the germinal vesicle stage, LGN is distributed both cytoplasmically and at the cortex. During maturation, LGN localizes to the meiotic spindle apparatus and cortical LGN becomes less concentrated at the actin cap region. Excessive LGN induces meiotic spindle organization defects by elongating the spindle and enhancing pole focusing, whereas depletion of LGN by RNA interference results in meiotic spindle deformation and chromosome misalignment. Furthermore, the N-terminus of LGN has the ability of full-length LGN to regulate spindle organization, whereas the C-terminus of LGN controls cortical localization and polarization. Our results reveal that LGN is cortically polarized in mouse oocytes and is critical for meiotic spindle organization.
文摘This research work aims to contribute in increasing the fruit set in citrus, given its importance in determining fruit yield. The authors evaluated the effects of phytohormones （auxins, gibberellins and cytokinins） in the mooring and features of orange fruit in cultivars Washington navel and Thomson （Citrus sinensis （L.） Osb.）, The experiment was established in a split plot randomized complete block design with five treatments and four replications. Flower tissue samples were stored in liquid N until the extraction of gibberellins and the identification and quantification of GA3. The results showed statistically significant difference （P 〈 0.05） between treatments in the number of fruits retained 129 d after flowering and the percentage of final tie. GA3 content ranged, on a dry weight basis, from 1.66 mg＇g1 in the control to 20.79 mg.g-1 in the high dose. The mean dose （32.2 mg.L-1 auxins, gibberellins 32.2 mg L-1 and 83.2 mg.L-1 cytokinins） caused the largest increase in fruit set.
基金supported by the National Natural Science Foundation of China(Grant No.11175257)
文摘A simulation of the properties of the shifting scintillator neutron detector using 6LiF/ZnS(Ag) scintillation screens is performed.The simulation results show that the light attenuation length of standard BC704 scintillator is about 0.65 mm.Its thermal neutron detection efficiency,gamma sensitivity and intrinsic spatial resolution can achieve around 50.0%,10 5and 0.18 mm(along X-axis) respectively.For the detector,air coupling position resolution is better than the silicone oil coupling.Some of the simulation results are compared with experimental results.They are in agreement.This work will be helpful for constructing neutron detector for high intensity powder diffractometer at Chinese spallation neutron source.
基金supported by the National Natural Science Foundation of China (Grant Nos. 3093002 and 30870046 to Shen YuLong,and 30700011 to Sheng DuoHong)the Promotive Research Fund for Excellent Young and Middle-aged Scientists of Shandong Province (Grant No. BS2010SW014 to Sheng DuoHong)
文摘Rad51/RadA paralogs found in eukaryotes and euryarchaea play important roles during recombination and repair,and mutations in one of the human Rad51 paralogs,Rad51C,are associated with breast and ovarian cancers.The hyperthermophilic crenarchaeon Sulfolobus tokodaii encodes four putative RadA paralogs and studies on these proteins may assist in understanding the functions of human Rad51 paralogs.Here,we report the biochemical characterization of stRadC2,a S.tokodaii RadA paralog.Pull-down assays revealed that the protein was able to interact with the recombinase,RadA,and the Holliday junction endonuclease,Hjc.stRadC2 inhibited the strand exchange activity of RadA and facilitated Hjc-mediated Holliday junction DNA cleavage in vitro.RT-PCR analysis revealed that stRadC2 transcription was immediately reduced after UV irradiation,but was restored to normal levels at the late stages of DNA repair.Our results suggest that stRadC2 may act as an anti-recombination factor in DNA recombinational repair in S.tokodaii.
基金Acknowledgments We apologize to colleagues whose work could not be cited owing to space constraints. J.H., H.M. and Y.W. are supported by the Ministry of Science and Technology of China （2011CB944603）, the National Natural Science Foundation of China （31370347）, and by funds from Fudan University and Rijk Zwaan. G.P.C. is supported by the US National Science Foundation （MCB- 1121563） and Rijk Zwaan.
文摘Meiosis comprises two rounds of nuclear division following a single phase of DNA replication, leading to the production of haploid gametes and is essential for sexual reproduction in eukaryotes. Unlike mitosis, meiosis involves homologous chromosome pairing, synapsis, and recombination during prophase I. Meiotic recombination not only ensures the accurate segregation of homologs, but also redistributes alleles among offspring. DNA synthesis is a critical process during meiotic recombination, but our understanding of the proteins that execute and regulate it is limited. This review summarizes the recent advances in defining the role of DNA synthesis in meiotic recombina- tion through analyses of DNA synthesis genes, with specific emphasis on DNA polymerases （e.g., Pole and PolS）, replication processivity factor RFC1 and translesion polymerases （e.g., Pol~）. We also present a new double strand break repair model for meiotic recombination, which includes lagging strand DNA synthesis and leading strand elongation. Finally, we propose that DNA synthesis is one of critical factors for discriminating meiotic recombination pathways and that this differentiation may be conserved among eukaryotes.
文摘Meiotic recombination is a deeply conserved process within eukaryotes that has a profound effect on patterns of natural genetic variation. During meiosis homologous chromosomes pair and undergo DNA double strand breaks generated by the Spo11 endonuclease. These breaks can be repaired as crossovers that result in reciprocal exchange between chromosomes. The frequency of recombination along chromosomes is highly variable, for example, crossovers are rarely observed in heterochromatin and the centromeric regions. Recent work in plants has shown that crossover hotspots occur in gene promoters and are associated with specific chromatin modifications, including H2 A.Z. Meiotic chromosomes are also organized in loop-base arrays connected to an underlying chromosome axis, which likely interacts with chromatin to organize patterns of recombination.Therefore, epigenetic information exerts a major influence on patterns of meiotic recombination along chromosomes, genetic variation within populations and evolution of plant genomes.
