癌组织中的遗传不稳定性的RAPD分析(简报)

肿瘤仍然是导致人类死亡的重要原因,由于缺乏深刻了解癌症的发生机制,尽管在过去25年中肿瘤的诊断和治疗都取得很大的进展,但肿瘤病人的存活率并没有显著的提高。目前有很多癌基因和抑癌基因如P16、P53、P73、ras、DCC和RB等     

棉蚜DNA多态性RAPD PCR分析(英文)

应用RAPD PCR技术研究了不同寄主和不同季节棉蚜的DNA多态性。从 2 0种随机引物中筛选出 3种引物 ,用它们的扩增结果进行Nei的遗传距离计算 ,并根据遗传距离对所研究的棉蚜种群做聚类分析。结果表明南京地区花椒上的棉蚜与其它 4种寄主上的棉蚜在DNA水平有明显的分化。聚类分析表明 ,棉蚜季节性种群可分为 3大类群 ,即春、秋季黄色型 ,春、秋季绿色型和黄色小型蚜 (伏蚜 )。而小型蚜的遗传关系与春、秋季绿色型最为接近。     

应用RAPD技术分析奥利亚罗非鱼和尼罗罗非鱼的基因多态性

以随机扩增多态DNA技术(RAPD）分析了奥利亚罗非鱼和尼罗罗非鱼两个养殖群体的群体内及群体间遗传关系,并探讨了该技术在种群鉴定中的应用。RAPD引物筛选结果表明,所测试的20个随机引物中(Table 1),除一个引物未扩增出任何片段外,其余19个引物均扩增出1～11个大小不等的片段,长度大部分在500—3000bp之间,共扩增出220个片段,平均每个引物产生55个片段。两群体间共有片段70条,大部分引物的扩增产物具有种间多态性,种群间相似系数为0.727。以筛选的引物对两种群不同个体(Fig．1,Table 2)及种群混合样品(Fig.2,Table 3)进行RAPD分析。结果表明,不同引物在扩增图谱上表现很大差异：奥利亚罗非鱼不同个体间表现为一致的扩增图谱,种内相似系数达1000,显示了其种群内遗传变异的缺乏;尼罗罗非鱼种内相似系数为0．827,个体间存在不同程度的多态性;两个种群间的相似系数分别为0．767和0.742,表明种间有较高的同源性,遗传距离为0．235,略低于国外的报道．此外,两个养殖群体间的扩增图谱比较也暗示了遗传渐渗现象的存在。实验表明,RAPD标记可以作为一种可靠的遗传标记,用于不同鱼类种群的鉴定,RAPD分析方法是一种快速,简便且行之有鼓的鉴定鱼类种群的方法。     

野生稻基因组随机扩增多态性DNA(RAPD)分析

用18个随机引物对2份栽培稻、12份包含有六个基因组型的野生稻DNA进行了扩增,共获得147个多态性DNA片断,把这些多态性DNA片断作为遗传位点用UPGMA法计算出各材料间的遗传相似性系数,并作了聚类分析．主要结果如下：1普通野生稻同栽培稻的亲缘关系很近,其中江永普通野生稻更接近于粳稻．2．CCDD组的Oryzalatifolia和EE组的O．australiensis遗传多态性相似。3．B、C、D、E组的遗传多态性相似,组成一个复合体,此复合体与A组的遗传多态性也相似,而F组则相距较远．4．O．mcyeriana和Rhynchofyzasabulata尚未确定组型,RAPD测定结果表明,前者与其它组型的种亲缘关系较远,后者则与AC复合体的种较近．     

中国柱花草炭疽病原菌遗传多态性的RAPD分析

在对中国柱花草炭疽病进行广泛调查和病原采样收集的基础上,利用RAPD分子标记技术对43个代表性菌株进行了基因组DNA分析,并与276份国外菌株进行了综合聚类分析。 结果表明所用8个引物的扩增片段位于0.3～2.8kb之间, 菌株间呈现显著的DNA多态性。以柱花草起源中心——南美的柱花草炭疽菌分类为基础,中国柱花草炭疽菌可划分成3大类型即Ⅱ、Ⅲ、Ⅵ类。中国菌株与来自柱花草起源中心——南美的菌株相比之下,其生物多样性和遗传变异性则相对简单。就中国菌株而言海南菌株与广西、广东菌株相比多样性较丰富, 中国柱花草胶孢炭疽菌正在出现种内遗传分化。 从聚类结果看,通常来自于同一个地理区域或同一个寄主基因型的菌株聚成一类, 即同一RAPD聚类组内的菌株通常来自于同一寄主基因型或同一地理区域。说明来自不同寄主基因型或物种的炭疽菌在遗传基因上具有专化性,而地理上隔离的国家或地区的柱花草炭疽病原菌各自具有相对独立的进化途径。     

海南和两广地区柱花草炭疽菌遗传多态性的RAPD分析

利用8个随机引物对来自海南、广东和广西的114个柱花草胶孢炭疽菌（Colletotrichum gloeosporioides）的菌株进行了随机扩增多态性DNA（RAPD）分析,扩增谱带大小0．2-3．0kb。8个随机引物中以CW38114扩增的谱带重现性和稳定性最好,共扩增出786条谱带,其中多态性谱带558条。供试菌株扩增图谱在260-650bp处有3条明显的共同特征谱带,在650—3000bp之间的谱带显示较大的多态性差异。聚类结果表明：供试菌株主要分为四大遗传类型。其中第Ⅰ类和第Ⅲ类有两个亚类;三省区的菌株遗传多态性丰富程度依次为海南〉广西〉广东,并表现出地区性分布差异。研究结果还表明柱花草炭疽菌株表现出一定程度的专化寄生性。     

海南和两广地区柱花草炭疽菌遗传多态性的RAPD分析

利用8个随机引物对来自海南、广东和广西的114个柱花草胶孢炭疽菌(Colletotrichum gloeosporioides)的菌株进行了随机扩增多态性DNA(RAPD)分析, 扩增谱带大小0.2-3.0 kb。8个随机引物中以CW38114扩增的谱带重现性和稳定性最好, 共扩增出786条谱带, 其中多态性谱带558条。供试菌株扩增图谱在260-650 bp处有3条明显的共同特征谱带, 在650-3 000 bp之间的谱带显示较大的多态性差异。聚类结果表明: 供试菌株主要分为四大遗传类型, 其中第I类和第III类有两个亚类; 三省区的菌株遗传多态性丰富程度依次为海南>广西>广东, 并表现出地区性分布差异。研究结果还表明柱花草炭疽菌株表现出一定程度的专化寄生性。     

枇杷栽培种的随机扩增DNA多态性(RAPD)研究

运用RAPD(Random Amplified Polylnorphic DNA)分析技术,对江苏省常绿果树研究中心16个枇杷(E．japonic Thunb Lindl)品种的基因组DNA进行了分析,从50个随机引物中筛选出19个引物,可从各个品种的基因组DNA扩增出谱带,总数为233个,其中多态性DNA片段176个,公共性DNA片段57个,表明这些枇杷品种间存在着丰富的遗传多样性。根据DNA片段的电泳结果,计算出品种间遗传相似系数及遗传距离,应用UPG—MA方法建立了品种遗传关系的系统树,将16个品种分成5类。从随机引物中筛选出2个随机引物能从各个品种的基因组DNA扩增出DNA片段,在16个枇杷品种中2个引物扩增出19个DNA片段,其中3个为公共,16个为多态性或单态性DNA片段。这些结果可为枇杷品种鉴定、分类、亲缘关系确立及品种选育中杂交组合亲本选配提供一定的依据。     

不同种源太子参的RAPD分析

应用RAPD标记方法分析了15个太子参〔Pseudostellaria heterophylla(Miq.)Pax ex Pax et Hoffm.〕种源间的遗传多样性和亲缘关系。10条随机引物共扩增出65条带,其中多态性条带37条,多态性条带百分率达56.9%。用聚类分析方法可将15个太子参种源分为4类;地理分布越近,太子参种源间的遗传差异越小。来源于安徽宣城的太子参种源遗传变异明显,辽宁凤城的野生太子参与山东地区的太子参栽培种源间的亲缘关系较近,与江苏各地太子参种源的亲缘关系则较远,这些种源均可作为育种材料。自然环境,尤其是生态环境的变化,对太子参的遗传变异有一定的影响。     

鲮鱼DAF和RAPD的比较研究

鲮鱼( Cirrhina molitorella)为南方“四大家鱼” 之一,目前其产量约占两广地区池塘鱼总产量的20%左右,具有产量高、抗病力强、肉质鲜美等特点,也是驰名中外的加工淡水鱼类产品。在利用 RAPD开展鲮鱼的遗传多样性研究中,发现珠江水系不同江段鲮 RAPD 遗传多样性不甚丰富。CaetanoAnollés等学者在 1991 年利用 DNA扩增指纹(DNA Amplification Fingerprinting,DAF)开展了基因组分析研究,他是利用非常短的随机引物(7-8bp,甚至 5bp)对不同模板 DNA 的酶链式扩增,采用高分辨率的聚丙烯酰胺疑胶电泳和银染显色检测 DNA 的多态性,引物比 RAPD 更短,因而扩增产物更多,获得的谱带更丰富,目前已在生物遗传多样性和品种鉴定、性状标记等方面得到应用。     

Classifications of ovarian cancer tissues by proteomic patterns

Ovarian cancer is a morphologically and biologically heterogeneous disease. The identification of type-specific protein markers for ovarian cancer would provide the basis for more tailored treatments, as well as clues for understanding the molecular mechanisms governing cancer progression. In the present study, we used a novel approach to classify 24 ovarian cancer tissue samples based on the proteomic pattern of each sample. The method involved fractionation according to pI using chromatofocusing with analytical columns in the first dimension followed by separation of the proteins in each pI fraction using nonporous RP HPLC, which was coupled to an ESI-TOF mass analyzer for molecular weight (MW) analysis. A 2-D mass map of the protein content of each type of ovarian cancer tissue samples based upon pI versus intact protein MW was generated. Using this method, the clear cell and serous ovarian carcinoma samples were histologically distinguished by principal component analysis and clustering analysis based on their protein expression profiles and subtype-specific biomarker candidates of ovarian cancers were identified, which could be further investigated for future clinical study.     

Electrophoretic protein patterns of Geotrichum and its teleomorphs

Total patterns of water-soluble proteins of 35 strains (7 species) of Galactomyces and Dipodascus strains with their respective Geotrichum anamorphs are compared. Quantitative differences among a number of species are found with iso-electric focusing; bands that characterize species are selected. Qualitative differences are found between the teleomorph genera.     

Recurrent gene loss correlates with the evolution of stomach phenotypes in gnathostome history

The stomach, a hallmark of gnathostome evolution, represents a unique anatomical innovation characterized by the presence of acid- and pepsin-secreting glands. However, the occurrence of these glands in gnathostome species is not universal; in the nineteenth century the French zoologist Cuvier first noted that some teleosts lacked a stomach. Strikingly, Holocephali (chimaeras), dipnoids (lungfish) and monotremes (egg-laying mammals) also lack acid secretion and a gastric cellular phenotype. Here, we test the hypothesis that loss of the gastric phenotype is correlated with the loss of key gastric genes. We investigated species from all the main gnathostome lineages and show the specific contribution of gene loss to the widespread distribution of the agastric condition. We establish that the stomach loss correlates with the persistent and complete absence of the gastric function gene kit—H⁺/K⁺-ATPase (Atp4A and Atp4B) and pepsinogens (Pga, Pgc, Cym)—in the analysed species. We also find that in gastric species the pepsinogen gene complement varies significantly (e.g. two to four in teleosts and tens in some mammals) with multiple events of pseudogenization identified in various lineages. We propose that relaxation of purifying selection in pepsinogen genes and possibly proton pump genes in response to dietary changes led to the numerous independent events of stomach loss in gnathostome history. Significantly, the absence of the gastric genes predicts that reinvention of the stomach in agastric lineages would be highly improbable, in line with Dollo''s principle.     

Polymorphisms of 5,10-methylenetetralydrofolate reductase (MTHFR), fruit and vegetable intake, and the risk of stomach cancer

Stomach cancer is a serious public health problem in China. 5,10-Methylenetetralydrofolate reductase (MTHFR) may be involved in both DNA methylation and DNA synthesis. Folate deficiency is associated with cancer risk that may be modulated by a genetic variation in the MTHFR gene in folate metabolism. The main goal of this study was to evaluate the association between polymorphisms of the MTHFR gene and the risk of stomach cancer. This study also explored the modification effects of fruit and vegetable intake (one of the main constituents is folate) on the risk of this disease. A population-based case-control study was conducted in Taixing, China, consisting of 206 newly diagnosed cases with primary stomach cancer and 415 healthy population controls. Polymorphisms of MTHFR C677T and A1298C were assayed by polymerase chain reaction-restricted fragment length polymorphism (PCR-RFLP) techniques. The data were analysed using the logistic regression model. No obvious association between the MTHFR A1298C polymorphism and the risk of stomach cancer was observed in this study. The frequencies of 677 C/C, C/T, and T/T were 34.5, 50.9, and 14.6%, respectively, in controls. The frequency of the MTHFR 677 wild homozygotic genotype was 25.8% in cases, which was lower than that in controls (34.5%). The adjusted odds ratio (OR) for the MTHFR 677 any T genotype was 2.05 (95% confidence interval (CI), 1.26-3.34) when compared with the C/C genotype. In the low fruit and vegetable intake group an increasing trend was observed with the T allele exposure, p=0.0056. The adjusted ORs were 1.68 (95% CI = 0.86-3.29) for the C/T genotype and 3.58 (95% CI = 1.46-8.75) for the T/T genotype, respectively. The MTHFR 677 any T genotype was associated with an increased risk of primary stomach cancer among the Chinese population. Folate deficiency might modify the MTHFR gene polymorphism and influence the risk of stomach cancer.     

Association between XPG polymorphisms and stomach cancer susceptibility in a Chinese population

Xeroderma pigmentosum group G (XPG) protein plays an important role in the DNA repair process by cutting the damaged DNA at the 3′ terminus. Previous studies have indicated some polymorphisms in the XPG gene are associated with stomach cancer susceptibility. We performed this hospital‐based case–control study to evaluate the association of four potentially functional XPG polymorphisms (rs2094258 C>T, rs751402 C>T, rs2296147 T>C and rs873601G>A) with stomach cancer susceptibility. The four single nucleotide polymorphisms (SNPs) were genotyped in 692 stomach cancer cases and 771 healthy controls. Logistic regression analysis was conducted, and odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the association of interest. Of the studied SNPs, XPG rs873601G>A polymorphism was found to significantly associate with stomach cancer susceptibility (AA versus GG/AG: OR = 1.31, 95% CI = 1.03–1.66, P = 0.027). Combined analysis of all SNPs revealed that the individuals with two of risk genotypes had a significantly increased stomach cancer risk (OR = 1.52, 95% CI = 1.13–2.06). In the stratification analysis, the association between the rs873601AA genotype and stomach cancer risk was observed in older group (>59 year), as well as patients with non‐cardia stomach cancer. Further combined analysis indicated men, smokers, or non‐drinkers more than one risk genotypes had a significantly increased stomach cancer risk. Our results indicate that XPG rs873601G>A polymorphism may be associated with the risk of stomach cancer. Further prospective studies with different ethnicities and large sample sizes are needed to validate our findings.     

Robust prediction of gene regulation in colorectal cancer tissues from DNA methylation profiles

DNA methylation is recognized as one of several epigenetic regulators of gene expression and as potential driver of carcinogenesis through gene-silencing of tumor suppressors and activation of oncogenes. However, abnormal methylation, even of promoter regions, does not necessarily alter gene expression levels, especially if the gene is already silenced, leaving the exact mechanisms of methylation unanswered. Using a large cohort of matching DNA methylation and gene expression samples of colorectal cancer (CRC; n = 77) and normal adjacent mucosa tissues (n = 108), we investigated the regulatory role of methylation on gene expression. We show that on a subset of genes enriched in common cancer pathways, methylation is significantly associated with gene regulation through gene-specific mechanisms. We built two classification models to infer gene regulation in CRC from methylation differences of tumor and normal tissues, taking into account both gene-silencing and gene-activation effects through hyper- and hypo-methylation of CpGs. The classification models result in high prediction performances in both training and independent CRC testing cohorts (0.92<AUC<0.97) as well as in individual patient data (average AUC = 0.82), suggesting a robust interplay between methylation and gene regulation. Validation analysis in other cancerous tissues resulted in lower prediction performances (0.69<AUC<0.90); however, it identified genes that share robust dependencies across cancerous tissues. In conclusion, we present a robust classification approach that predicts the gene-specific regulation through DNA methylation in CRC tissues with possible transition to different cancer entities. Furthermore, we present HMGA1 as consistently associated with methylation across cancers, suggesting a potential candidate for DNA methylation targeting cancer therapy.     

Long-term follow-up of cancer patients treated with gene therapy medicinal products

European Union requirements are discussed for the long-term follow-up of advanced therapy medicinal products, as well as how they can be applied to cancer patients treated with gene therapy medicinal products in the context of clinical trials, as described in a specific guideline issued by Gene Therapy Working Party at the European Medicine Agency.