Experimental DNA-Binding and Computer Modelling Studies on an Analogue of the Anti-Tumour Drug Amsacrine

Abstract

The DNA-binding properties of the anti-cancer drug amsacrine and a 9-aminoacridine analogue substituted at the 4 position with a 4-methanesulphonanilido-group, have been examined by means of unwinding, melting and equilibrium binding experiments. These find that the latter compound is at least as effective as a DNA-binder and intercalator as amsacrine itself. Molecular modelling and energetic calculations have confirmed this, and have produced plausible intercalation geometries. These show that there are subtle differences in the low-energy minor groove arrangements adopted by the substituents of the two drugs. Speculation is advanced that these differences may be relevant to the marked differences in cytotoxicity shown by the two compounds.     

Breakdown of self-incompatibility during pistil development in Lycopersicon peruvianum by modified bud pollination

Summary Stylar self-incompatibility barriers in L. peruvianum can be avoided if pollen germination and growth through immature pistils is promoted under specific environmental conditions approximately 2–3 days before the initiation of anthesis. Since immature stigmas lack sufficient exudate for pollen germination, the sandwiching of a thin layer of pollen germination medium between the stigma and a mineral oil layer containing pollen allows precocious pollen germination and some compatible pollen tube growth through the style. This procedure is rapid, inexpensive, applicable in the field, and makes efficient use of pollen. Consistent though low seed yields have been obtained. A high proportion of aborted seed, seedling lethals, and aberrant seedling phenotypes in selfed progeny indicate the presence of strong post-zygotic barriers to such selfing. No evidence for a reduction in the strength of the SI response with increasing pistil age was observed.     

Pathogen-avoidance mechanisms and the stigmatization of obese people

Humans possess pathogen-avoidance mechanisms that respond to the visual perception of morphological anomalies in others. We investigated whether obesity may trigger these mechanisms. Study 1 revealed that people who are chronically concerned about pathogen transmission have more negative attitudes toward obese people; this effect was especially pronounced following visual exposure to obese individuals. Study 2 revealed that obesity is implicitly associated with disease-connoting concepts; this effect was especially pronounced when the threat of pathogen transmission is highly salient. Evolved pathogen-detection mechanisms are hypersensitive, and they appear to play a role in the stigmatization of obese people.     

精神分裂症易感基因的研究进展

精神分裂症迄今病因未明,家系研究、双生子与寄养子的研究显示了精神分裂症的遗传倾向,各国学者开展了许多寻找其致病基因的研究工作。已经有大量关于精神分裂症易感基因的报道,有些结果也在后续试验中取得了较好的重复性。本文主要就精神分裂症易感基因的研究近况做一综述。     

肥胖症易感基因——FTO的研究进展

FTO（fat mass and obesity associated）是肥胖症易感基因,表达于人体各组织,且在下丘脑中高表达。它能编码核酸去甲基化酶,通过去甲基化作用影响其他相关基因表达。FTO的基因多态性与体重指数（BMI）及肥胖症密切相关。FTO能够影响能量摄入及能量消耗,并通过多种途径诱导人群中肥胖症及2型糖尿病等相关疾病的发生,而FTO失活的小鼠能够避免肥胖发生。主要综述了FTO基因多态性与肥胖等疾病易感性的相关性、FTO可能的作用机制和FTO对人群中能量平衡的影响。     

Genetic analysis of mortality in murine angiostrongyliasis costaricensis using SMXA recombinant inbred mouse strains

The SMXA recombinant inbred mouse strain set was produced by systematic inbreeding from the F2 generation of a cross between two progenitor inbred strains, A/J and SM/J, which differed markedly with respect to the patterns of infection with Angiostrongylus costaricensis. We have applied this set to genetic analysis of mouse susceptibility to this nematode infection. The mortality was variable among substrains of the SMXA RI strains, indicating the involvement of multiple genes. Linkage analysis showed several chromosomal regions closely linked to mortality; chromosome 6 (D6Rik86, 87; P0.001), 10 (D10Rik66–D10Mit12; P=0.0058), 13 (D13Rik79, 80; P=0.0096) and 17 (D17Mit28–D17Rik76; P=0.0088).     

人类疾病遗传易感性研究方法进展

遗传易感性是指基于个人遗传背景的多基因遗传病发病风险,即来源于父母一方或双方的特定遗传变异在某些情况下会诱发疾病.在特定疾病的发病机制中某些高外显率的遗传变异发挥重要作用,此类疾病通过患病家系分析即可定位疾病相关遗传变异;但另一些低外显率变异的作用则不明显,需要大规模患病人群分析来解析遗传机制.近年来,随着二代测序和多...     

基因多态性与慢性阻塞性肺疾病易感性关系研究的新进展

慢性阻塞性肺疾病(chronic obstructive pulmonary disease,COPD)是一组气流受限为特征的肺部疾病,气流受限不完全可逆,呈进行性发展。它受遗传因素,环境因素以及遗传-环境相互作用的影响。目前,虽然其确切的病因及发病机制不甚明了,但是近年来的研究表明COPD是一种多基因调控的疾病。本文综述了几个较为重要的遗传基因多态性与COPD易感性关系的近期研究进展。     

K-rasG12V mediated lung tumor models identified three new quantitative trait loci modifying events post-K-ras mutation

A high incidence of oncogenic K-ras mutations is observed in lung adenocarcinoma of human cases and carcinogen-induced animal models. The process of oncogenic K-ras-mediated lung adenocarcinogenesis can be dissected into two parts: pre- and post-K-ras mutation. Adoption of transgenic lines containing a flox-K-rasG12V transgene eliminates the use of chemical carcinogens and enables us to study directly crucial events post-K-ras mutation without considering the cellular events involved with oncogenic K-ras mutation, e.g., distribution and metabolism of chemical carcinogens, DNA repair, and somatic recombination by host factors. We generated two mouse strains C57BL/6J-Ryr2^tm1Nobs and A/J-Ryr2^tm1Nobs in which K-rasG12V can be transcribed from the cytomegalovirus early enhancer/chicken beta actin promoter in virtually any tissue. Upon K-rasG12V induction in lung epithelial cells by an adenovirus expressing the Cre recombinase, the number of tumors in the C57BL/6J-Ryr2^tm1Nobs/+ mouse line was 12.5 times that in the A/J-Ryr2^tm1Nobs/+ mouse line. Quantitative trait locus (QTL) analysis revealed that new three modifier loci, D3Mit19, D3Mit45 and D11Mit20, were involved in the differential susceptibility between the two lines. In addition, we found that differential expression of the wild-type K-ras gene, which was genetically turn out to be anti-oncogenic activity on K-rasG12V, could not account for the different susceptibility in our two K-rasG12V-mediated lung tumor models. Thus, we provide a genetic system that enables us to explore new downstream modifiers post-K-ras mutation.     

Common variants in the obesity-associated genes FTO and MC4R are not associated with risk of colorectal cancer

BackgroundObesity is a convincing risk factor for colorectal cancer. Genetic variants in or near FTO and MC4R are consistently associated with body mass index and other body size measures, but whether they are also associated with colorectal cancer risk is unclear.MethodsIn the discovery stage, we tested associations of 677 FTO and 323 MC4R single nucleotide polymorphisms (SNPs) 100 kb upstream and 300 kb downstream from each respective locus with risk of colorectal cancer in data from the Colon Cancer Family Registry (CCFR: 1960 cases; 1777 controls). Next, all SNPs that were nominally statistically significant (p < 0.05) in the discovery stage were included in replication analyses in data from the Genetics and Epidemiology of Colorectal Cancer Consortium (GECCO: 9716 cases; 9844 controls).ResultsIn the discovery stage, 43 FTO variants and 18 MC4R variants were associated with colorectal cancer risk (p < 0.05). No SNPs remained statistically significant in the replication analysis after accounting for multiple comparisons.ConclusionWe found no evidence that individual variants in or near the obesity-related genes FTO and MC4R are associated with risk of colorectal cancer.     

人类肥胖基因瘦素蛋白的原核表达

目的：原核表达人类肥胖基因瘦素蛋白,方法：以携人类肥胖基因的pUC119-ob为模拟,PCR扩增瘦素蛋白基因片段,并克隆到pET-32a构建重组表达质粒pET-32a-ob,经酶切和测序鉴定后,转化至大肠埃希菌DH5α中表达,SDS-PAGE电泳鉴定表达产物。结果：测序和限制性分析均证明了pET-32a-ob的序列正确,转化的DH5α可高效表达一个30kD融合蛋白,与预期结果一致。结论：经pET-32a-ob转化的DH5α可有效表达重组人类瘦素蛋白,为进一步研究瘦素蛋白的生物活性提供了基础。     

Variants of the CD40 ligand gene are not associated with increased susceptibility to tuberculosis in West Africa

Evidence for linkage between tuberculosis and human chromosomal region Xq26 has previously been described. The costimulatory molecule CD40 ligand, encoded by TNFSF5 and located at Xq26.3, is a promising positional candidate. Interactions between CD40 ligand and CD40 are involved in the development of humoral- and cell-mediated immunity, as well as the activation of macrophages, which are the primary host and effector cells for Mycobacterium tuberculosis. We hypothesised that common variation within TNFSF5 might affect susceptibility to tuberculosis disease and, thus, might be responsible for the observed linkage to Xq26. Sequencing 32 chromosomes from a Gambian population identified nine common polymorphisms within the coding, 3 and 5 regulatory sequences of the gene. Six single nucleotide polymorphisms (SNPs) and a 3 microsatellite were genotyped in 121 tuberculosis patients and their available parents. No association with tuberculosis was detected for these variants using a transmission disequilibrium test, although one SNP at –726 showed some evidence of association in males. This finding, however, did not replicate in a separate case control study of over 1,200 West African individuals. We conclude that common genetic variation in TNFSF5 is not likely to affect tuberculosis susceptibility in West Africa and the linkage observed in this region is not due to variation in TNFSF5.Sadly, Professor Steve Bennett passed away in March 2003     

SCN9A基因多态与颞叶癫痫相关性

目的:探讨SCN9A基因多态与颞叶癫痫相关性。方法:搜集179例癫痫患者及正常对照组236例血样,提取全基因组DNA。聚合酶链反应-限制性片段长度多态(PCR-RFLP)、测序法检测四个标签SNPs多态性,比较两组各位点基因型和等位基因频率的差异。结果:SCN9A基因rs12620053和rs7588632位点多态在癫痫组与对照组间存在显著差异(P0.05),而rs2893013和rs4465779位点多态在癫痫组与对照组间无显著差异(P0.05)。结论:SCN9A基因rs12620053和rs7588632位点多态与癫痫易感性相关,而位点rs2893013和rs4465779与癫痫易感性无关。