In studying the XCAP-C-like protein in the root meristematic cells of Allium sativa L., the nuclei were isolated from the cells and the nuclear matrices prepared. A 165 kD polypeptide, which is equivalent to XCAP-C in...In studying the XCAP-C-like protein in the root meristematic cells of Allium sativa L., the nuclei were isolated from the cells and the nuclear matrices prepared. A 165 kD polypeptide, which is equivalent to XCAP-C in molecular weight, was demonstrated in the nuclei by SDS-PAGE, and was then proved to be an XCAP-C-like protein by Western blot using an anti-XCAP-C antiserum, but neither the polypeptide nor the XCAP-C-like protein was detected in die nuclear matrix. The nuclei, Chromosomes and chromosome scaffolds were observed to emanate strong, specific fluorescence after labeled with the anti-XCAP-C antiserum and an FITC-conjugated secondary antibody, indicating their containment of the XCAP-C-like protein. It was confirmed by viewing with immunoelectron microscopy that the gold particles representing the localization of the XCAP-C-like protein were found to be mainly distributed in the condensed chromatin regions of the nuclei and chromosomes.展开更多
Recently the antichromosome antisera from several scleroderma patients have been found to recognize the pellicle of metaphase and anaphase chromosomes. In order to identify the pellicle components, we used these antic...Recently the antichromosome antisera from several scleroderma patients have been found to recognize the pellicle of metaphase and anaphase chromosomes. In order to identify the pellicle components, we used these antichromosome antisera to screen a human embryonic cDNA library. The sequences of the positive clones are identical to the cDNA gene sequence of CENP-C (centromere protein C), a human centromere autoantigen. This result suggusts that CENP-C is a component of the pellicle of human metaphase and anaphase chromosomes.展开更多
Here we report a family with a clinical spectrum of Pachyonychia Congenita Tarda (PCT) encompassing two generations via a balanced chromosomal translocation between 4q26 and 12p12.3. We discuss the effects of chromoso...Here we report a family with a clinical spectrum of Pachyonychia Congenita Tarda (PCT) encompassing two generations via a balanced chromosomal translocation between 4q26 and 12p12.3. We discuss the effects of chromosomal translocations on gene expression through involved breakpoints and structural gene abnormalities detected by array CGH. We believe that the family we present gives further insight to the better understanding of molecular and structural basis of keratin disorders, and to the late onset and genetic basis of PCT through the possible role of C-type lectins and human epithelial membrane protein1 (EMP1). Better understanding of the molecular basis of keratin disorders is the foundation for improved diagnosis, genetic counseling and novel therapeutic approaches to overcome the current treatment limitations related to this disease.展开更多
To examine phosphatase and tensin homology deleted in chromosome 10 (PTEN),hypoxia-inducible factor-1 alpha (HIF-1 alpha) gene expressions and their relation to vascular endothelial growth factor(VEGF) protein express...To examine phosphatase and tensin homology deleted in chromosome 10 (PTEN),hypoxia-inducible factor-1 alpha (HIF-1 alpha) gene expressions and their relation to vascular endothelial growth factor(VEGF) protein expression in the patients with human colorectal adenomas and adenocarcinomas.Methods The expression of PTEN,HIF-1 alpha gene was detected by using in situ hybridization,and the VEGF expression levels by immunohistochemistry in colorectal adenomas and primary colorectal adenocarcinoma.Results Strong expression of HIF-1 alpha was detectable in the majority of colorectal dadenocarcinoma,particularly surrounding areas of necrosis in adenocarcinoma.PTEN,HIF-1 alpha mRNA and VEGF protein were positive in 51.6%,67.7% and 59.7% respectively in 62 cases of adenocarcinomas,and 77.8%,44.4% and 33.3% respectively in 18 cases of adenomas.The positive rate of VEGF was higher in the patients with colorectal adenocarcinomas than that in those with adenomas,whereas that of PTEN mRNA was contrary.HIF-1 mRNA expression was correlated significantly with lymph node metastasis,liver metastasis,Duke’s stage and recurrence.During colorectal tumor progression,the expression of HIF-1 alpha mRNA was positively correlated with the VEGF protein expression (χ2= 4.751 ,P<0.05),but negatively with the PTEN mRNA expression(χ2=21.84,P<0.01).Conclusion The absence or low expression of PTEN and the increased levels of HIF-1α and VEGF may paly an important role in carcinogenesis and progression of colorectal carcinoma.These results suggest that VEGF upregulated by HIF-1 alpha gene may be involved in angiogenesis of colorectal adenocarcinoma.4 refs,1 tab.展开更多
Kluyveromyces marxianus is a food-safe yeast with great potential for producing heterologous proteins.Improving the yield in K.marxianus remains a challenge and incorporating large-scale functional modules poses a tec...Kluyveromyces marxianus is a food-safe yeast with great potential for producing heterologous proteins.Improving the yield in K.marxianus remains a challenge and incorporating large-scale functional modules poses a technical obstacle in engineering.To address these issues,linear and circular yeast artificial chromosomes of K.marxianus(KmYACs)were constructed and loaded with disulfide bond formation modules from Pichia pastoris or K.marxianus.These modules contained up to seven genes with a maximum size of 15 kb.KmYACs carried telomeres either from K.marxianus or Tetrahymena.KmYACs were transferred successfully into K.marxianus and stably propagated without affecting the normal growth of the host,regardless of the type of telomeres and configurations of KmYACs.KmYACs increased the overall expression levels of disulfide bond formation genes and significantly enhanced the yield of various heterologous proteins.In high-density fermentation,the use of KmYACs resulted in a glucoamylase yield of 16.8 g/l,the highest reported level to date in K.marxianus.Transcriptomic and metabolomic analysis of cells containing KmYACs suggested increased flavin adenine dinucleotide biosynthesis,enhanced flux entering the tricarboxylic acid cycle,and a preferred demand for lysine and arginine as features of cells overexpressing heterologous proteins.Consistently,supplementing lysine or arginine further improved the yield.Therefore,KmYAC provides a powerful platform for manipulating large modules with enormous potential for industrial applications and fundamental research.Transferring the disulfide bond formation module via YACs proves to be an efficient strategy for improving the yield of heterologous proteins,and this strategy may be applied to optimize other microbial cell factories.展开更多
AIM: By using comparative genomic hybridization, gain of 3q was found in 45-86% cases of esophageal squamous cell carcinoma (EC-SCC). Chromosome 3q25.3-qter is the minimal common region with several oncogenes found wi...AIM: By using comparative genomic hybridization, gain of 3q was found in 45-86% cases of esophageal squamous cell carcinoma (EC-SCC). Chromosome 3q25.3-qter is the minimal common region with several oncogenes found within this region. However, amplification patterns of these genes in EC-SCC have never been reported. The possible association of copy number changes of these genes with pathologic characteristics is still not clear. METHODS: Real-time quantitative PCR (Q-PCR) was performed to analyze the copy number changes of 13 candidate genes within this region in 60 primary tumors of EC-SCC, and possible association of copy number changes with pathologic characteristics was analyzed by statistics. Immunohistochemistry (IHC) study was also performed on another set of 111 primary tumors of EC-SCC to verify the association between TP63 expression change and lymph node metastasis status. RESULTS: The average copy numbers (±SE) per haploid genome of individual genes in 60 samples were (from centromere to telomere): SSR3: 4.19 (±0.69); CCNL1: 5.24 (±0.67); SMC4L1: 2.01 (±0.16); EVI1: 2.02 (±0.12); hTERC. 5.28 (±0.54); SKIL 2.71 (±0.14); EIF5A2. 1.95 (±0.12); ECT2: 9.18 (±1.68); PIK3CA: 8.13 (±1.17); EIF4G1: 1.07 (±0.05); 557: 3.07 (±0.25); TP63: 2.51 (±0.22); TFRC. 2.42 (±0.19). Four clusters of amplification were found: SSR3 and CCLN1 at 3q25.31; hTERC and SKIL at 3q26.2; ECT2 and PIK3CA at 3q26.31-q26.32; and 55T, TP63 and TFRC at 3q27.3-q29. Patients with lymph node metastasis had significantly lower copy number of TP63 in the primary tumor than those without lymph node metastasis. IHC study on tissue arrays also showed that patients with lymph node metastasis have significantly lower TP63 staining score in the primary tumor than those without lymph node metastasis. CONCLUSION: This study showed that different amplification patterns were seen among different genes within 3q25.3-qter in EC-SCC, and several novel candidate oncogenes (SSR3, SMC4L1, ECT2, and SST) were identified. TP63 is amplified in early stage of EC-SCC carcinogenesis but down-regulated in advanced stage of disease.展开更多
An extract from chromatin with 0.35 M NaCl is a heterogenous class of nonhistone chromosomal proteins. On the basis of their respective electrophoretic mobilities in polyacrylamide gel, the 0.35 M NaCl extract is divi...An extract from chromatin with 0.35 M NaCl is a heterogenous class of nonhistone chromosomal proteins. On the basis of their respective electrophoretic mobilities in polyacrylamide gel, the 0.35 M NaCl extract is divided into 2 groups: the low mobility group (LMG) proteins and the high mobility group (HMG) proteins. Up to date, a lot of researches have been mainly concentrated on the latter. It is thought展开更多
All organisms must transmit genetic information to offspring through cell division, and mitotic spindle participates in the process. Spindle dynamics through depolymerization or polymerization of microtubules generate...All organisms must transmit genetic information to offspring through cell division, and mitotic spindle participates in the process. Spindle dynamics through depolymerization or polymerization of microtubules generates the driving force required for chromosome movements in mitosis. To date, studies have shown that microtubule arrays control the directions of cell division and diverse microtubule-associated proteins regulate cell division. But a clear picture of how microtubules and microtubule-associated proteins modulate cell division remains unknown. Depletion of end-binding protein 1 by RNA-mediated inhibition shows that one of the microtubule-associated proteins, end-binding protein 1, plays a crucial role in mitotic spindle formation and promotes microtubule dynamics and is needed for the proper segregation of mitotic chromosomes during anaphase in Drosophila cells. Here, we review the properties of end-binding protein 1 and the roles of end-binding protein 1 in regulating microtubule behavior and in cell cycle.展开更多
It is shown here that one can induce prematurely condensed chromosomes (PCCs) in G1-phase human (HeLa) and mouse (FT210) cells by treating them with the protein phosphatase inhibitor calyculin A. However, histone H1 i...It is shown here that one can induce prematurely condensed chromosomes (PCCs) in G1-phase human (HeLa) and mouse (FT210) cells by treating them with the protein phosphatase inhibitor calyculin A. However, histone H1 is not phosphorylated in these G1-PCCs. It has previously been proposed that histone H1 phosphorylation is responsible for mitotic chromosome condensation, but our results suggest that this is not the case. They indicate instead that phosphorylation of histone H1 is not required for chromosome condensation. It is known that the Cdk1 protein kinase, which triggers mitosis and also phosphorylates histone H1, cannot be activated in G1-phase because mitotic cyclins are not present. Since calyculin A induces PCCs in G1-phase in the absence of active Cdk1, our results suggest that inactivation of protein phosphatases may be just as important for the onset of chromosome condensation and other mitotic events as the activation of protein kinases.展开更多
Dinoflagellates are a very large and diverse group of eukaryotic algae that play a major role in aquatic food webs of both fresh water and marine habitats. Moreover, the toxic members of this group pose a health threa...Dinoflagellates are a very large and diverse group of eukaryotic algae that play a major role in aquatic food webs of both fresh water and marine habitats. Moreover, the toxic members of this group pose a health threat in the form of red tides. Finally, dinoflagellates are of great evolutionary importance,because of their taxonomic position, and their unusual chromosome structure and composition. While the cytoplasm of dinoflagellates is typically eukaryotic, the nucleus is unique when compared to the nucleus of other eukaryotes. More specifically, while the chromosomes of all other eukaryotes contain histones,dinoflagellate chromosomes lack histones completely. There are no known exceptions to this observation: all dinoflagellates lack histones, and all other eukaryotes contain histones. Nevertheless, dinoflagellates remain a relatively unstudied group of eukaryotes.展开更多
IN the late 1970s, biochemical analysis and electron microscopy of isolated, histone-depleted mitotic chromosomes demonstrated the existence of a central scaffold consisting mainly of nonhistone proteins (NHPs) in met...IN the late 1970s, biochemical analysis and electron microscopy of isolated, histone-depleted mitotic chromosomes demonstrated the existence of a central scaffold consisting mainly of nonhistone proteins (NHPs) in metaphase chromosomes. Subsequently, by using silver impregnation techniques and light microscopy, Howell et al. showed the presence of an axial chromatid core in relatively intact chromosomes of mammals; this core is believed to be展开更多
目的·分析癌-睾丸抗原(cancer-testis antigen,CTA)家族成员SPANXB(sperm protein associated with the nucleus on the X chromosome B)在肝癌中的表达及其与肝癌患者预后之间的相关性,并探究SPANXB对肝癌细胞增殖的影响及其潜在...目的·分析癌-睾丸抗原(cancer-testis antigen,CTA)家族成员SPANXB(sperm protein associated with the nucleus on the X chromosome B)在肝癌中的表达及其与肝癌患者预后之间的相关性,并探究SPANXB对肝癌细胞增殖的影响及其潜在机制。方法·利用癌症基因组图谱(The Cancer Genome Atlas,TCGA)数据库中的肝癌样本数据,分析SPANXB在肝癌组织中的表达及其与患者生存期的相关性。构建稳定敲低SPANXB与稳定过表达SPANXB的肝癌细胞系,利用活细胞成像实验、EdU细胞增殖实验和平板克隆形成实验评估SPANXB对肝癌细胞增殖的影响。通过RNA测序(RNA-sequence,RNA-seq)探究SPANXB调控肝癌细胞增殖的相关通路,并利用细胞周期实验验证SPANXB对肝癌细胞周期的影响。采用免疫沉淀-质谱联用技术(immunoprecipitation-mass spectrometry,IP-MS)探索与SPANXB相互作用的蛋白,并使用免疫共沉淀(co-immunoprecipitation,Co-IP)进行验证。结果·SPANXB mRNA在肝癌组织中的表达高于正常组织(P=0.003),且与肝癌患者的生存期呈负相关。稳定敲低SPANXB可降低肝癌细胞的增殖能力、克隆形成能力,而稳定过表达SPANXB则可促进这些过程。RNA-seq的结果显示,SPANXB的敲低可下调DNA复制与G1/S细胞周期转换相关通路,细胞周期实验的结果显示SPANXB的敲低可导致肝癌细胞周期发生改变。IP-MS和Co-IP结果显示,SPAXNB与有丝分裂停滞缺陷2样蛋白1(mitotic arrest deficient 2-like protein 1,MAD2L1)、WD重复域蛋白5(WD repeat domain 5,WDR5)等细胞周期相关蛋白存在相互作用。结论·SPANXB的高表达与肝癌的预后呈负相关,其可能通过与MAD2L1、WDR5相互作用调控细胞周期并增强肝癌细胞的增殖活性。展开更多
文摘In studying the XCAP-C-like protein in the root meristematic cells of Allium sativa L., the nuclei were isolated from the cells and the nuclear matrices prepared. A 165 kD polypeptide, which is equivalent to XCAP-C in molecular weight, was demonstrated in the nuclei by SDS-PAGE, and was then proved to be an XCAP-C-like protein by Western blot using an anti-XCAP-C antiserum, but neither the polypeptide nor the XCAP-C-like protein was detected in die nuclear matrix. The nuclei, Chromosomes and chromosome scaffolds were observed to emanate strong, specific fluorescence after labeled with the anti-XCAP-C antiserum and an FITC-conjugated secondary antibody, indicating their containment of the XCAP-C-like protein. It was confirmed by viewing with immunoelectron microscopy that the gold particles representing the localization of the XCAP-C-like protein were found to be mainly distributed in the condensed chromatin regions of the nuclei and chromosomes.
文摘Recently the antichromosome antisera from several scleroderma patients have been found to recognize the pellicle of metaphase and anaphase chromosomes. In order to identify the pellicle components, we used these antichromosome antisera to screen a human embryonic cDNA library. The sequences of the positive clones are identical to the cDNA gene sequence of CENP-C (centromere protein C), a human centromere autoantigen. This result suggusts that CENP-C is a component of the pellicle of human metaphase and anaphase chromosomes.
文摘Here we report a family with a clinical spectrum of Pachyonychia Congenita Tarda (PCT) encompassing two generations via a balanced chromosomal translocation between 4q26 and 12p12.3. We discuss the effects of chromosomal translocations on gene expression through involved breakpoints and structural gene abnormalities detected by array CGH. We believe that the family we present gives further insight to the better understanding of molecular and structural basis of keratin disorders, and to the late onset and genetic basis of PCT through the possible role of C-type lectins and human epithelial membrane protein1 (EMP1). Better understanding of the molecular basis of keratin disorders is the foundation for improved diagnosis, genetic counseling and novel therapeutic approaches to overcome the current treatment limitations related to this disease.
文摘To examine phosphatase and tensin homology deleted in chromosome 10 (PTEN),hypoxia-inducible factor-1 alpha (HIF-1 alpha) gene expressions and their relation to vascular endothelial growth factor(VEGF) protein expression in the patients with human colorectal adenomas and adenocarcinomas.Methods The expression of PTEN,HIF-1 alpha gene was detected by using in situ hybridization,and the VEGF expression levels by immunohistochemistry in colorectal adenomas and primary colorectal adenocarcinoma.Results Strong expression of HIF-1 alpha was detectable in the majority of colorectal dadenocarcinoma,particularly surrounding areas of necrosis in adenocarcinoma.PTEN,HIF-1 alpha mRNA and VEGF protein were positive in 51.6%,67.7% and 59.7% respectively in 62 cases of adenocarcinomas,and 77.8%,44.4% and 33.3% respectively in 18 cases of adenomas.The positive rate of VEGF was higher in the patients with colorectal adenocarcinomas than that in those with adenomas,whereas that of PTEN mRNA was contrary.HIF-1 mRNA expression was correlated significantly with lymph node metastasis,liver metastasis,Duke’s stage and recurrence.During colorectal tumor progression,the expression of HIF-1 alpha mRNA was positively correlated with the VEGF protein expression (χ2= 4.751 ,P<0.05),but negatively with the PTEN mRNA expression(χ2=21.84,P<0.01).Conclusion The absence or low expression of PTEN and the increased levels of HIF-1α and VEGF may paly an important role in carcinogenesis and progression of colorectal carcinoma.These results suggest that VEGF upregulated by HIF-1 alpha gene may be involved in angiogenesis of colorectal adenocarcinoma.4 refs,1 tab.
基金supported by the National Key Research and Development Program of China(Nos.2021YFA0910601 and 2021YFC2100203)Shanghai Municipal Education Commission(2021-03-52)Science and Technology Research Program of Shanghai(19DZ2282100).
文摘Kluyveromyces marxianus is a food-safe yeast with great potential for producing heterologous proteins.Improving the yield in K.marxianus remains a challenge and incorporating large-scale functional modules poses a technical obstacle in engineering.To address these issues,linear and circular yeast artificial chromosomes of K.marxianus(KmYACs)were constructed and loaded with disulfide bond formation modules from Pichia pastoris or K.marxianus.These modules contained up to seven genes with a maximum size of 15 kb.KmYACs carried telomeres either from K.marxianus or Tetrahymena.KmYACs were transferred successfully into K.marxianus and stably propagated without affecting the normal growth of the host,regardless of the type of telomeres and configurations of KmYACs.KmYACs increased the overall expression levels of disulfide bond formation genes and significantly enhanced the yield of various heterologous proteins.In high-density fermentation,the use of KmYACs resulted in a glucoamylase yield of 16.8 g/l,the highest reported level to date in K.marxianus.Transcriptomic and metabolomic analysis of cells containing KmYACs suggested increased flavin adenine dinucleotide biosynthesis,enhanced flux entering the tricarboxylic acid cycle,and a preferred demand for lysine and arginine as features of cells overexpressing heterologous proteins.Consistently,supplementing lysine or arginine further improved the yield.Therefore,KmYAC provides a powerful platform for manipulating large modules with enormous potential for industrial applications and fundamental research.Transferring the disulfide bond formation module via YACs proves to be an efficient strategy for improving the yield of heterologous proteins,and this strategy may be applied to optimize other microbial cell factories.
基金Supported by the National Microarray and Gene Expression Analysis Core Facility of the National Research Program for Genomic Medicine at National Yang-Ming University (http://www.ym.edu. tw/microarray),annual project Grant From National Science Council (Grant NO. NSC 92-2314-B-075-055), Taiwan, China
文摘AIM: By using comparative genomic hybridization, gain of 3q was found in 45-86% cases of esophageal squamous cell carcinoma (EC-SCC). Chromosome 3q25.3-qter is the minimal common region with several oncogenes found within this region. However, amplification patterns of these genes in EC-SCC have never been reported. The possible association of copy number changes of these genes with pathologic characteristics is still not clear. METHODS: Real-time quantitative PCR (Q-PCR) was performed to analyze the copy number changes of 13 candidate genes within this region in 60 primary tumors of EC-SCC, and possible association of copy number changes with pathologic characteristics was analyzed by statistics. Immunohistochemistry (IHC) study was also performed on another set of 111 primary tumors of EC-SCC to verify the association between TP63 expression change and lymph node metastasis status. RESULTS: The average copy numbers (±SE) per haploid genome of individual genes in 60 samples were (from centromere to telomere): SSR3: 4.19 (±0.69); CCNL1: 5.24 (±0.67); SMC4L1: 2.01 (±0.16); EVI1: 2.02 (±0.12); hTERC. 5.28 (±0.54); SKIL 2.71 (±0.14); EIF5A2. 1.95 (±0.12); ECT2: 9.18 (±1.68); PIK3CA: 8.13 (±1.17); EIF4G1: 1.07 (±0.05); 557: 3.07 (±0.25); TP63: 2.51 (±0.22); TFRC. 2.42 (±0.19). Four clusters of amplification were found: SSR3 and CCLN1 at 3q25.31; hTERC and SKIL at 3q26.2; ECT2 and PIK3CA at 3q26.31-q26.32; and 55T, TP63 and TFRC at 3q27.3-q29. Patients with lymph node metastasis had significantly lower copy number of TP63 in the primary tumor than those without lymph node metastasis. IHC study on tissue arrays also showed that patients with lymph node metastasis have significantly lower TP63 staining score in the primary tumor than those without lymph node metastasis. CONCLUSION: This study showed that different amplification patterns were seen among different genes within 3q25.3-qter in EC-SCC, and several novel candidate oncogenes (SSR3, SMC4L1, ECT2, and SST) were identified. TP63 is amplified in early stage of EC-SCC carcinogenesis but down-regulated in advanced stage of disease.
文摘An extract from chromatin with 0.35 M NaCl is a heterogenous class of nonhistone chromosomal proteins. On the basis of their respective electrophoretic mobilities in polyacrylamide gel, the 0.35 M NaCl extract is divided into 2 groups: the low mobility group (LMG) proteins and the high mobility group (HMG) proteins. Up to date, a lot of researches have been mainly concentrated on the latter. It is thought
文摘All organisms must transmit genetic information to offspring through cell division, and mitotic spindle participates in the process. Spindle dynamics through depolymerization or polymerization of microtubules generates the driving force required for chromosome movements in mitosis. To date, studies have shown that microtubule arrays control the directions of cell division and diverse microtubule-associated proteins regulate cell division. But a clear picture of how microtubules and microtubule-associated proteins modulate cell division remains unknown. Depletion of end-binding protein 1 by RNA-mediated inhibition shows that one of the microtubule-associated proteins, end-binding protein 1, plays a crucial role in mitotic spindle formation and promotes microtubule dynamics and is needed for the proper segregation of mitotic chromosomes during anaphase in Drosophila cells. Here, we review the properties of end-binding protein 1 and the roles of end-binding protein 1 in regulating microtubule behavior and in cell cycle.
文摘It is shown here that one can induce prematurely condensed chromosomes (PCCs) in G1-phase human (HeLa) and mouse (FT210) cells by treating them with the protein phosphatase inhibitor calyculin A. However, histone H1 is not phosphorylated in these G1-PCCs. It has previously been proposed that histone H1 phosphorylation is responsible for mitotic chromosome condensation, but our results suggest that this is not the case. They indicate instead that phosphorylation of histone H1 is not required for chromosome condensation. It is known that the Cdk1 protein kinase, which triggers mitosis and also phosphorylates histone H1, cannot be activated in G1-phase because mitotic cyclins are not present. Since calyculin A induces PCCs in G1-phase in the absence of active Cdk1, our results suggest that inactivation of protein phosphatases may be just as important for the onset of chromosome condensation and other mitotic events as the activation of protein kinases.
文摘Dinoflagellates are a very large and diverse group of eukaryotic algae that play a major role in aquatic food webs of both fresh water and marine habitats. Moreover, the toxic members of this group pose a health threat in the form of red tides. Finally, dinoflagellates are of great evolutionary importance,because of their taxonomic position, and their unusual chromosome structure and composition. While the cytoplasm of dinoflagellates is typically eukaryotic, the nucleus is unique when compared to the nucleus of other eukaryotes. More specifically, while the chromosomes of all other eukaryotes contain histones,dinoflagellate chromosomes lack histones completely. There are no known exceptions to this observation: all dinoflagellates lack histones, and all other eukaryotes contain histones. Nevertheless, dinoflagellates remain a relatively unstudied group of eukaryotes.
文摘IN the late 1970s, biochemical analysis and electron microscopy of isolated, histone-depleted mitotic chromosomes demonstrated the existence of a central scaffold consisting mainly of nonhistone proteins (NHPs) in metaphase chromosomes. Subsequently, by using silver impregnation techniques and light microscopy, Howell et al. showed the presence of an axial chromatid core in relatively intact chromosomes of mammals; this core is believed to be
文摘目的·分析癌-睾丸抗原(cancer-testis antigen,CTA)家族成员SPANXB(sperm protein associated with the nucleus on the X chromosome B)在肝癌中的表达及其与肝癌患者预后之间的相关性,并探究SPANXB对肝癌细胞增殖的影响及其潜在机制。方法·利用癌症基因组图谱(The Cancer Genome Atlas,TCGA)数据库中的肝癌样本数据,分析SPANXB在肝癌组织中的表达及其与患者生存期的相关性。构建稳定敲低SPANXB与稳定过表达SPANXB的肝癌细胞系,利用活细胞成像实验、EdU细胞增殖实验和平板克隆形成实验评估SPANXB对肝癌细胞增殖的影响。通过RNA测序(RNA-sequence,RNA-seq)探究SPANXB调控肝癌细胞增殖的相关通路,并利用细胞周期实验验证SPANXB对肝癌细胞周期的影响。采用免疫沉淀-质谱联用技术(immunoprecipitation-mass spectrometry,IP-MS)探索与SPANXB相互作用的蛋白,并使用免疫共沉淀(co-immunoprecipitation,Co-IP)进行验证。结果·SPANXB mRNA在肝癌组织中的表达高于正常组织(P=0.003),且与肝癌患者的生存期呈负相关。稳定敲低SPANXB可降低肝癌细胞的增殖能力、克隆形成能力,而稳定过表达SPANXB则可促进这些过程。RNA-seq的结果显示,SPANXB的敲低可下调DNA复制与G1/S细胞周期转换相关通路,细胞周期实验的结果显示SPANXB的敲低可导致肝癌细胞周期发生改变。IP-MS和Co-IP结果显示,SPAXNB与有丝分裂停滞缺陷2样蛋白1(mitotic arrest deficient 2-like protein 1,MAD2L1)、WD重复域蛋白5(WD repeat domain 5,WDR5)等细胞周期相关蛋白存在相互作用。结论·SPANXB的高表达与肝癌的预后呈负相关,其可能通过与MAD2L1、WDR5相互作用调控细胞周期并增强肝癌细胞的增殖活性。
