Identification of a chromosome 18q gene that is altered in colorectal cancers

Allelic deletions involving chromosome 18q occur in more than 70 percent of colorectal cancers. Such deletions are thought to signal the existence of a tumor suppressor gene in the affected region, but until now a candidate suppressor gene on this chromosomal arm had not been identified. A contiguous stretch of DNA comprising 370 kilobase pairs (kb) has now been cloned from a region of chromosome 18q suspected to reside near this gene. Potential exons in the 370-kb region were defined by human-rodent sequence identities, and the expression of potential exons was assessed by an "exon-connection" strategy based on the polymerase chain reaction. Expressed exons were used as probes for cDNA screening to obtain clones that encoded a portion of a gene termed DCC; this cDNA was encoded by at least eight exons within the 370-kb genomic region. The predicted amino acid sequence of the cDNA specified a protein with sequence similarity to neural cell adhesion molecules and other related cell surface glycoproteins. While the DCC gene was expressed in most normal tissues, including colonic mucosa, its expression was greatly reduced or absent in most colorectal carcinomas tested. Somatic mutations within the DCC gene observed in colorectal cancers included a homozygous deletion of the 5' end of the gene, a point mutation within one of the introns, and ten examples of DNA insertions within a 0.17-kb fragment immediately downstream of one of the exons. The DCC gene may play a role in the pathogenesis of human colorectal neoplasia, perhaps through alteration of the normal cell-cell interactions controlling growth.     

The human gene encoding GM-CSF is at 5q21-q32, the chromosome region deleted in the 5q- anomaly

Human granulocyte-macrophage colony-stimulating factor (GM-CSF) is a 22,000-dalton glycoprotein that stimulates the growth of myeloid progenitor cells and acts directly on mature neutrophils. A full-length complementary DNA clone encoding human GM-CSF was used as a probe to screen a human genomic library and isolate the gene encoding human GM-CSF. The human GM-CSF gene is approximately 2.5 kilobase pairs in length with at least three intervening sequences. The GM-CSF gene was localized by somatic cell hybrid analysis and in situ hybridization to human chromosome region 5q21-5q32, which is involved in interstitial deletions in the 5q- syndrome and acute myelogenous leukemia. An established, human promyelocytic leukemia cell line, HL60, contains a rearranged, partially deleted GM-CSF allele and a candidate 5q- marker chromosome, indicating that the truncated GM-CSF allele may reside at the rejoining point for the interstitial deletion on the HL60 marker chromosome.     

Location of a major susceptibility locus for familial schizophrenia on chromosome 1q21-q22

Schizophrenia is a complex disorder, and there is substantial evidence supporting a genetic etiology. Despite this, prior attempts to localize susceptibility loci have produced predominantly suggestive findings. A genome-wide scan for schizophrenia susceptibility loci in 22 extended families with high rates of schizophrenia provided highly significant evidence of linkage to chromosome 1 (1q21-q22), with a maximum heterogeneity logarithm of the likelihood of linkage (lod) score of 6.50. This linkage result should provide sufficient power to allow the positional cloning of the underlying susceptibility gene.     

Identification of a thyroid hormone receptor that is pituitary-specific

Three cellular homologs of the v-erbA oncogene were previously identified in the rat; two of them encode high affinity receptors for the thyroid hormone triiodothyronine (T3). A rat complementary DNA clone encoding a T3 receptor form of the ErbA protein, called r-ErbA beta-2, was isolated. The r-ErbA beta-2 protein differs at its amino terminus from the previously described rat protein encoded by c-erbA beta and referred to as r-ErbA beta-1. Unlike the other members of the c-erbA proto-oncogene family, which have a wide tissue distribution, r-erbA beta-2 appears to be expressed only in the anterior pituitary gland. In addition, thyroid hormone downregulates r-erbA beta-2 messenger RNA but not r-erbA beta-1 messenger RNA in a pituitary tumor-derived cell line. The presence of a pituitary-specific form of the thyroid hormone receptor that may be selectively regulated by thyroid hormone could be important for the differential regulation of gene expression by T3 in the pituitary gland.     

The human gene for the beta subunit of nerve growth factor is located on the proximal short arm of chromosome 1

Fragments of the recently cloned human gene for the beta subunit of nerve growth factor (beta-NGF) were used as hybridization probes in analyzing two sets of rodent-human somatic cell hybrids for the presence of human beta-NGF sequences. Results from the first set of hybrids assigned the human beta-NGF gene to chromosome 1 and ruled out the presence of sequences of comparable homology on any other chromosome. With the second set of hybrids, which contained seven different, but overlapping, regions of chromosome 1, the NGF locus was mapped to band 1p22.     

Identification of p53 gene mutations in bladder cancers and urine samples

Although bladder cancers are very common, little is known about their molecular pathogenesis. In this study, invasive bladder cancers were evaluated for the presence of gene mutations in the p53 suppressor gene. Of 18 tumors evaluated, 11 (61 percent) were found to have genetic alterations of p53. The alterations included ten point mutations resulting in single amino acid substitutions, and one 24-base pair deletion. In all but one case, the mutations were associated with chromosome 17p allelic deletions, leaving the cells with only mutant forms of the p53 gene products. Through the use of the polymerase chain reaction and oligomer-specific hybridization, p53 mutations were identified in 1 to 7 percent of the cells within the urine sediment of each of three patients tested. The p53 mutations are the first genetic alterations demonstrated to occur in a high proportion of primary invasive bladder cancers. Detection of such mutations ex vivo has clinical implications for monitoring individuals whose tumor cells are shed extracorporeally.     

Comparative genetic mapping revealed powdery mildew resistance gene MlWE4 derived from wild emmer is located in same genomic region of Pm36 and Ml3D232 on chromosome 5BL

Powdery mildew, caused by Blumeria graminis f. sp. tritici, is one of the most devastating wheat diseases. Wild emmer wheat(Triticum turgidum ssp. dicoccoides) is a promising source of disease resistance for wheat. A powdery mildew resistance gene conferring resistance to B. graminis f. sp. tritici isolate E09, originating from wild emmer wheat, has been transferred into the hexaploid wheat line WE4 through crossing and backcrossing. Genetic analyses indicated that the powdery mildew resistance was controlled by a single dominant gene, temporarily designated Ml WE4. By mean of comparative genomics and bulked segregant analysis, a genetic linkage map of Ml WE4 was constructed, and Ml WE4 was mapped on the distal region of chromosome arm 5BL. Comparative genetic linkage maps showed that genes Ml WE4, Pm36 and Ml3D232 were co-segregated with markers XBD37670 and XBD37680, indicating they are likely the same gene or alleles in the same locus. The co-segregated markers provide a starting point for chromosome landing and map-based cloning of Ml WE4, Pm36 and Ml3D232.     

水稻温敏黄转绿突变体v5的鉴定和基因定位

通过对粳稻品种‘日本晴’进行60Coγ射线诱变,从M2中筛选到一个温度敏感的黄转绿突变体v5(virescent5)。突变体植株在较低温度(20～24℃)下叶色表现为黄色,而植株在较高温度(26～30℃)下叶色几乎表现为绿色。对叶绿素含量的测定显示出低温条件下突变体叶绿素含量显著低于野生型植株;对相关农艺性状考察显示出突变体单株产量显著低于野生型。遗传分析表明,该突变表型受一对隐性核基因控制,利用F2群体(v5/Kasalath)将OsV5基因定位于第9染色体长臂,在BAC AP005838上标记STS1与BAC AP005702上标记STS5312之间166.5 kb的区段上。     

Regulation of the erythropoietin gene: evidence that the oxygen sensor is a heme protein

Erythropoietin (Epo), the hormone that stimulates red blood cell production, is synthesized in the kidney and liver in response to hypoxia. The human hepatoma cell line Hep3B regulates its production of Epo in a physiologic manner. Either hypoxia or cobalt chloride markedly increases expression of Epo mRNA as well as production of biologically active and immunologically distinct Epo protein. New protein synthesis is required before the induction of increased levels of hypoxia- or cobalt-induced Epo mRNA. Hypoxia, cobalt chloride, and nickel chloride appear to stimulate Epo production through a common pathway. The inhibition of Epo production at low partial pressures of oxygen by carbon monoxide provides evidence that a heme protein is integrally involved in the oxygen-sensing mechanism. This hypothesis is further supported by the finding that when heme synthesis is blocked, hypoxia-, cobalt-, and nickel-induced Epo production are all markedly inhibited. A model is proposed in which a ligand-dependent conformational change in a heme protein accounts for the mechanism by which hypoxia as well as cobalt and nickel stimulate the production of Epo.     

猪睾丸表达序列37 (TEX37)克隆、mRNA表达及蛋白质功能生物信息学分析

目的以版纳微型猪近交系(Banna mini-pig inbred line, BMI)为材料,初步探索猪睾丸表达序列37 (TEX37) 基因的特性和功能,为该基因在猪精子生成过程的作用研究奠定基础。方法利用Oligo7软件设计特异引物扩增BMI TEX37基因整个编码区,应用实时荧光定量PCR技术检测BMI 15个组织的TEX37 mRNA表达谱,并初步预测TEX37蛋白质的功能,最后构建TEX37的多物种氨基酸系统进化树。结果扩增得到BMI TEX37编码区序列长561 bp,编码186个氨基酸,基因登录号KU705619,氨基酸登录号AOC89037。多组织相对荧光定量表达分析表明：TEX37基因在睾丸中呈相对最高表达,在其他组织中呈相对较低表达。生物信息学分析表明：TEX37蛋白质含有TSC21结构域,二级结构以无规则卷曲为主,N末端疏水,C末端亲水,有2类磷酸化位点,无跨膜螺旋结构和信号肽。系统聚类表明：BMI与其他物种相似度在67%以上,进化较保守。结论该研究可为TEX37基因在猪精子生成方面的作用机理研究提供参考。     

江苏省江宁样区土壤系统分类中基层分类的研究

依据《中国土壤系统分类 (修订方案 )》和《中国土壤系统分类———理论·方法·实践》的原则与方法 ,选择江宁县淳化镇的低丘岗地和冲地农田 (70 0hm2 )作为典型区段。按照景观、地貌与母质类型 ,设置了 5 1个土壤观察剖面 ,并采集土壤剖面各层段土样进行理化分析。最后拟定出 11个特征土层 ,划分出 6个土系。     

Identification of mutations in the COL4A5 collagen gene in Alport syndrome

X-linked Alport syndrome is a hereditary glomerulonephritis in which progressive loss of kidney function is often accompanied by progressive loss of hearing. Ultrastructural defects in glomerular basement membranes (GBM) of Alport syndrome patients implicate an altered structural protein as the cause of nephritis. The product of COL4A5, the alpha 5(IV) collagen chain, is a specific component of GBM within the kidney, and the gene maps to the same X chromosomal region as does Alport syndrome. Three structural aberrations were found in COL4A5, in intragenic deletion, a Pst I site variant, and an uncharacterized abnormality, which appear to cause nephritis and deafness, with allele-specific severity, in three Alport syndrome kindreds in Utah.     

安农0711小麦品种3B染色体茎秆强度位点鉴定

倒伏是限制小麦产量进一步提升的主要因素之一,而茎秆强度是衡量小麦抗倒伏性的重要指标。为了鉴定控制茎秆强度基因位点,以安农0711（较强的茎秆强度和抗倒性）和河农825（较弱的茎秆强度和抗倒性）进行杂交构建的重组自交系群体为试验材料,于2017年测定其茎秆强度,利用SSR标记将控制小麦茎秆强度的位点（Qss.ahau-3B）初步定位于3B染色体上的wmc231-barc248标记之间,物理距离约为68~162 Mb。进一步利用小麦660K SNP芯片扫描两个亲本及高低池,并基于目标区段内差异的SNP,共开发了13个CAPS标记,将控制小麦茎秆强度的位点进一步缩短在EX-6650-barc248之间（150~162 Mb）。该研究结果为后续目标位点精细定位以及候选基因克隆提供了重要理论依据。     

番茄第9号染色体上抗晚疫病基因的发掘及表达模式

为提供番茄晚疫病抗病育种候选基因,本研究以高抗晚疫病的CLN2037E自交系和感病5#自交系为实验材料,在前期使用分子标记将CLN2037E中存在的抗晚疫病基因定位在第9号染色体的基础上,利用晚疫病病菌诱导CLN2037E的cDNA文库、番茄基因组CDS数据库、本地Blast程序及实时荧光定量PCR技术,发掘与第9号染色体上EST最佳匹配的CDS以及对晚疫病病菌的响应模式。结果发掘出6条抗晚疫病的候选基因,其中Solyc09g097960、Solyc09g082810和Solyc09g065760在5#自交系和CLN2037E自交系中均响应晚疫病病菌,Solyc09g092030和Solyc09g090430在2个自交系中分别被抑制和不响应晚疫病病菌,Solyc09g008670STBZ的表达在5#自交系中被抑制,而在CLN2037E中被诱导。为验证该基因的功能,成功构建Solyc09g008670基因的过表达和VIGS(Virus Induced Gene Silencing)沉默载体。     

酿酒酵母新型分泌缺陷突变株突变基因的鉴定

对酿酒酵母新型分泌缺陷突变株分泌缺陷特性进行鉴定,结果发现Invertase和Bgl2p的分泌在37℃下受阻,但电镜观察未见胞内分泌小泡积累.用酵母基因组文库挽救突变株,克隆挽救片段上各候选基因与pRS315构建重组质粒并转化突变株以检验它们的挽救效果,发现具有挽救功能的基因是TEL2.从突变株克隆了TEL2的全序列并进行序列测定,检测到了两个突变位点,即:P367→L,S545→F.对该基因突变前后编码的蛋白质产物进行了生物信息学分析,推测出TEL2蛋白可能参与极性外排途径的结构功能域在246～434氨基酸范围内.本试验首次揭示了端粒长度调控基因TEL2在极性外排途径中的重要作用.     

Location of gene for beta subunit of human T-cell receptor at band 7q35, a region prone to rearrangements in T cells

The T-cell receptor is formed by two chains, alpha and beta, for which specific clones were recently obtained. In this report the gene for the beta chain of the human T-cell receptor was located on the long arm of chromosome 7, band q35, by means of in situ hybridization. This chromosome region in T cells is unusually prone to develop breaks in vivo, perhaps reflecting instability generated by somatic rearrangement of T-cell receptor genes during normal differentiation in this cell lineage.