一种改良的人精子染色体分析方法

分析精子染色体只能在受精后,更确切地说,只能待其在卵细胞内复制缩合成为原核染色体之后。因此,为分析人类两性配子染色体必需有人卵母细胞。然而,要获得大量的人卵母细胞来进行人配子核型分析极为     

父源基因组重编程中组蛋白变体的作用

卵母细胞具有重编程精子基因组以确保胚胎正常发育的能力。精子入卵后,父源基因组会经历组蛋白替换鱼精蛋白,全基因组去甲基化等过程,从而启动胚胎发育。组蛋白H3的变体H3.3可以替换核小体中的典型组蛋白H3.1和H3.2,从而修饰染色质结构和影响基因表达。在早期胚胎发育过程中H3.3的缺失将导致染色体的过度凝集和错误分离。我们综述了组蛋白变体H3.3及其分子伴侣在精子发生、受精和早期胚胎发育中的作用,特别是H3.3对父源基因组重编程的重要性,这对理解受精后全能性合子的形成及着床前发育具有重要意义。     

18例正常男性精子染色体直接分析结果初报

人生殖细胞染色体畸变率已成为目前人们非常感兴趣的研究课题。由于人卵难以获得,以及人精子染色体仅在受精后才能观察,所以要直接分析人类生殖细胞染色体结构是不可能的。1978年Rudak 等首次报告了用人精子使地鼠卵受精后对人精子染色体结     

慢病毒载体介导的转基因整合位点研究方法

慢病毒载体整合到宿主细胞的染色体上可以长期稳定表达,目前已成为基因治疗和转基因动物载体研究的热点.慢病毒载体整合的位置效应是影响外源基因表达的重要因素,慢病毒载体整合位点的研究是探索外源基因整合机制的手段之一.转基因整合位点研究的方法主要有5种:荧光原位杂交、个体基因组文库筛选法、反向PCR、接头PCR、锚定PCR.近来的研究后发现整合位点之间可能存在一些共同特征.     

人类精子染色体构成的直接分析

已知人的全部受孕中,最少有10％染色体不正常,估计1—2％是由于接受染色体不正常的精子所造成的。为了研究雄配子在造成畸形染色体受孕中的真正作用,以及影响染色体畸形精子产生和存活的因素,必须直接分析精子染色体。然而,精子染色体,在减数分裂中期Ⅱ之后,一直到受精卵的雌雄原核准备第一次分裂之前不再重现。本报     

496对反复流产夫妇体细胞染色体分析

对４９６对反复流产夫妇体细胞染色体进行了检查与分析，发现染色体异常５８例，占被检夫妇的１１．６９％，占总人数的５．８５％。其中染色体易位型２３例，性染色体异常１１例，其他异常３例，９号染色体倒位５例，多态现象３例，单个或几个细胞核型异常１３例。男女比例为男性异常率小于女性。通过分析，认为染色体易位畸变与性染色体数目畸变是主要的流产原因之一。在造成流产的性别方面结合人精子染色体畸变研究，提出男女染色体畸变时变率总差异是性染色体畸变率差异造成，而在受精方面不存在优先受精的可能性。对于单个或几个核型异常是否造成流产的问题，提出要结合病人的配子染色体检查，防止生殖细胞染色体异常率升高造成流产的漏诊情况发生。对多态现象提出要进一步研究这些人群的配子染色体情况，以便了解多态现象的真正遗传效应。     

慢性HBV感染不同阶段肝组织HBV cccDNA含量与IL-10、IFN-γ的相关性研究

目前尚无特效药能够治愈慢性乙型肝炎,主要原因是HBV cccDNA的存在,HBV cccDNA是HBV前基因组RNA复制的原始模板,可稳定地存在于肝细胞核中.只有宿主的免疫系统能够清除HBV cccDNA.     

慢性HBV感染不同阶段肝组织HBV cccDNA含量与IL-10、IFN-γ的相关性研究

目前尚无特效药能够治愈慢性乙型肝炎,主要原因是HBV cccDNA的存在,HBV cccDNA是HBV前基因组RNA复制的原始模板,可稳定地存在于肝细胞核中.只有宿主的免疫系统能够清除HBV cccDNA.     

慢性HBV感染不同阶段肝组织HBV cccDNA含量与IL-10、IFN-γ的相关性研究

目前尚无特效药能够治愈慢性乙型肝炎,主要原因是HBV cccDNA的存在,HBV cccDNA是HBV前基因组RNA复制的原始模板,可稳定地存在于肝细胞核中.只有宿主的免疫系统能够清除HBV cccDNA.     

Rep蛋白介导的定点整合研究进展

建立安全可靠的、治疗基因能长期表达的系统是基因治疗的重要目标,这一目标可以通过促进目的DNA序列定点整合至宿主基因组的特定位置而达到。腺相关病毒的非结构蛋白Rep与顺式元件联合运用可以介导外源基因定点整合至人类基因组19号染色体AAVS1位点,本文就Rep蛋白的特性、介导整合机制及近年来在介导定点整合方面的研究作一综述。     

Integration of hepatitis B virus DNA in chronically infected patients assessed by Alu‐PCR

Hepatitis B virus (HBV) infection is the main risk factor for hepatocellular carcinoma (HCC) worldwide. Integration of HBV DNA into the human genome has been found in >80% of HBV‐related HCC cases. Some studies have, however, found similar integration patterns in tumorous and nontumorous tissues. Thus, the role of integrations for the development of HCC as well as the rate of integration in different stages of infection remain unclear. The aim of this study was to investigate integrations in patients without HCC, representing different stages of chronic HBV (CHB) infection. Extracted DNA in liver biopsies from 74 patients (one with 2 available biopsies) with CHB infection was analyzed by Alu‐PCR. Amplicons were further analyzed by Sanger sequencing. Integration was detected in 39 biopsies (52%) as an amplicon containing both human and HBV sequences by Alu‐PCR with one primer targeting a region in the HBV genome. Integrations were found in patients representing the different stages of CHB infection. A majority of the HBV sequences were located upstream or downstream of nucleotide position 1820, which previously has been identified as a common breakpoint in the HBV genome in integrated sequences. Approximately 60% of the HBV integrations were found in noncoding regions of the human genome. Integrations of HBV DNA into the human genome is an event frequently found in mild phases of chronic hepatitis.     

A pilot systematic genomic comparison of recurrence risks of hepatitis B virus-associated hepatocellular carcinoma with low- and high-degree liver fibrosis

Background

Chronic hepatitis B virus (HBV) infection leads to liver fibrosis, which is a major risk factor in hepatocellular carcinoma (HCC) and an independent risk factor of recurrence after HCC tumor resection. The HBV genome can be inserted into the human genome, and chronic inflammation may trigger somatic mutations. However, how HBV integration and other genomic changes contribute to the risk of tumor recurrence with regards to the different degree of liver fibrosis is not clearly understood.

Methods

We sequenced mRNAs of 21 pairs of tumor and distant non-neoplastic liver tissues of HBV-HCC patients and performed comprehensive genomic analyses of our RNAseq data and public available HBV-HCC sequencing data.

Results

We developed a robust pipeline for sensitively identifying HBV integration sites based on sequencing data. Simulations showed that our method outperformed existing methods. Applying it to our data, 374 and 106 HBV host genes were identified in non-neoplastic liver and tumor tissues, respectively. When applying it to other RNA sequencing datasets, consistently more HBV integrations were identified in non-neoplastic liver than in tumor tissues. HBV host genes identified in non-neoplastic liver samples significantly overlapped with known tumor suppressor genes. More significant enrichment of tumor suppressor genes was observed among HBV host genes identified from patients with tumor recurrence, indicating the potential risk of tumor recurrence driven by HBV integration in non-neoplastic liver tissues. We also compared SNPs of each sample with SNPs in a cancer census database and inferred samples’ pathogenic SNP loads. Pathogenic SNP loads in non-neoplastic liver tissues were consistently higher than those in normal liver tissues. Additionally, HBV host genes identified in non-neoplastic liver tissues significantly overlapped with pathogenic somatic mutations, suggesting that HBV integration and somatic mutations targeting the same set of genes are important to tumorigenesis. HBV integrations and pathogenic mutations showed distinct patterns between low and high liver fibrosis patients with regards to tumor recurrence.

Conclusions

The results suggest that HBV integrations and pathogenic SNPs in non-neoplastic tissues are important for tumorigenesis and different recurrence risk models are needed for patients with low and high degrees of liver fibrosis.

     

Malignant Transformation of Human Embryonic Liver Cells Induced by Hepatitis B Virus and Aflatoxin B_1

Hepatocellular carcinoma (HCC) is a worldwide distribut ed disease accounting for 473 000 newly developed cases ofHCC annually in the world and 235 000 cases in China[1]. Epidemiological and laboratory investigations havedemonstrated that hepatitis…     

Encapsidation of truncated human hepatitis B virus genomes through trans-complementation of the core protein and polymerase

Mutational analyses and complementation tests were used to analyze the strategy of packaging and of replication of human hepatitis B virus (HBV). By creating new restriction enzyme sites and by varying the genome length of HBV mutants, we identified that the mutated genomes could be encapsidated through trans-complementation of the polymerase and/or core protein. This study demonstrates that the polymerase of HBV, similar to that of duck hepatitis B virus (DHBV), is synthesized de novo instead of through a core-polymerase fusion protein. The results also indicate that both the polymerase and the core protein can be supplied in trans during viral packaging, and that the complementation is not due to recombination between the cotransfected plasmids. Furthermore, HBV genome deleted down to 2.4 kb is still able to be encapsidated, as measured by the endogenous polymerase reaction. Taken together, these results provide a basis for using HBV as a vector to deliver foreign genes into hepatocytes and for defining the location of the packaging signal on the HBV genome.     

乙型肝炎病毒DNA在肝癌患者基因组中的检测

目的：为了研究乙型肝炎病毒ＤＮＡ在人类基因组中的整合作用与肝癌发生之间的关系。方法：采用聚合酶链反应技术,对肝癌细胞基因组中的乙肝病毒ＤＮＡ第Ｖ 区段进行了测定。结果：１２ 例肝癌细胞基因组８ 例为阳性,１０ 例肝癌患者外周血细胞基因组均为阴性。结论：乙型肝炎病毒ＤＮＡ 的整合与肝癌发生有密切关系。     

Inhibition of Hepatitis B virus gene expression by single and dual small interfering RNA treatment

RNA interference (RNAi) has been successfully applied in suppression of Hepatitis B virus (HBV) replication. To circumvent the problem that mutation in HBV genome may result in resistance when siRNA is further developed as an anti-viral drug, in this study, we established a dual small interfering RNA (siRNA) expression system, which could simultaneously express two different siRNA molecules that can specifically target two genes. To test the effectiveness of this system, we applied this new approach to express simultaneously two different 21-bp hairpin siRNA duplexes that specifically attack the HBs and HBx genes of HBV, respectively, in Bel-7402 and HepG2.2.15 cells. Results indicated that dual siRNA could simultaneously inhibit the expression of HBs and HBx gene by 83.7% and 87.5%, respectively, based on luciferase assays. In addition, dual siRNA molecules were able to significantly reduce the amount of HBV core associated DNA, which is considered as an intracellular replicative intermediate, and the viral DNA in culture supernatant. Therefore, this dual siRNA system provides a more powerful tool for the study of gene function and implicates a potential application in the treatment of viral infection.     

Absence of hepatitis B virus (HBV) DNA in children born after exposure of their mothers to HBV during in vitro fertilization.

During in vitro fertilization, 22 human embryos were exposed to hepatitis B virus (HBV) in contaminated human serum present in the culture medium. All mothers experienced hepatitis B during the first trimester of pregnancy, and two had hepatitis B surface antigen and HBV DNA, as determined by PCR, at the time of delivery. No HBV DNA was found in serum or lymphocytes from the exposed 22 infants. HBV DNA was also absent from one infant at autopsy.