Nucleotide sequence and in vitro expression of the capsid protein gene of tobacco ringspot virus

The nucleotide sequence of the 3' terminal 2022 nucleotides (nt) of tobacco ringspot virus (TobRV) RNA 2 has been determined. Protein microsequence analysis of the amino-terminal residues of purified capsid protein localized the capsid protein gene between nt 2014 and 583 (from the 3' terminus) of this sequence. The proteolytic cleavage site that is processed to liberate the capsid protein from the RNA 2-encoded polyprotein was identified as Cys-Ala. The predicted translation product from the gene is a 477 amino acid long polypeptide with a calculated MW of 53 kDa. The gene was modified at the 5' end to facilitate sub-cloning, and to provide it with a methionine initiation codon. The modified gene was sub-cloned, transcribed in vitro and expressed in a rabbit reticulocyte lysate translation system, where it directed the synthesis of a 53 kDa polypeptide. Garnier-Osguthorpe-Robson analyses of the secondary structure of the capsid protein predicted the presence of three beta sheet domains, which suggests that this nepovirus capsid may be structurally analogous to those of the como- and picornaviruses. These and other results from computer analyses of the nucleic acid and amino acid sequences, and comparisons with the capsid proteins of nepoviruses and other related viruses are discussed.     

The use of a double-marker shuttle vector to study DNA double-strand break repair in wild-type and radiation-sensitive mutants of the yeast Saccharomyces cerevisiae

An episomal DNA vector (YpJA18), encoding two selectable recombinant yeast genes (TRP1, URA3), was constructed to assess the fidelity of DNA repair in haploid repair-competent (RAD) wild-type yeast and several radiation-sensitive mutants. Either a DNA double-strand break (DSB) or a double-strand gap of 169 bp (DSG) was introduced by restriction enzymes in-vitro within the coding sequence of the URA3 gene of this vector. To eliminate transfer artefacts, selection was first applied for the undamaged TRP1 gene followed by counter selection for URA3 gene activity, which indicated correct repair of the DSB and DSG. Correct repair of the damaged URA3 gene was found to be about 90% in RAD cells (normalized for the expression of undamaged URA3 in TRP ⁺ transformants). Plasmids isolated from the transformants (URA ⁺ TRP ⁺) carry both unique sites (ApaI and NcoI) within the URA3 gene indicating the precise restitution of the 169-bp gap. An excision-repair-defective rad4-4 mutant repaired these lesions as correctly as RAD cells, whereas the mutants rad50-1, rad51-1 and rad54-1, proven to be defective in DSB repair and mitotic recombination, showed less than 5% correct repair of such lesions. In contrast, a representative of the RAD6 epistasis group of genes, the rev2-1 mutant which is sensitive towards UV and ionizing radiation, had a significantly reduced ability (about 20%) for the correct repair of both DSBs and DSGs.     

DNA analysis of two patients with a non-fluorescent y chromosome

Summary Results of DNA study on two patients of gonadal dysgenesis with a 45,X/46,X,Ynf (non-fluorescent Y chromosome) karyotype are described. In one patient who developed gonadoblastoma, all 12 loci on the non-fluorescent part of Yq were detected. Another patient did not have gonadoblastoma at 20 years, and only the proximal 6 loci out of 12 were detected.     

Functional mapping of the activity of the R region in the human T-cell leukemia virus type I long terminal repeat to increase gene expression

We previously demonstrated the activity of the R fragment in the long terminal repeat of human T-cell leukemia virus type I for elevation of the level of gene expression. In this study, the fragment was deleted with BAL31 nuclease to determine its functional domain. Series of the shortened R fragments were linked to the simian virus 40 promoter unit, which regulated expression of a reporter gene. Examination with the R fragments deleted from the 5 and 3 ends showed that borders of the functional domain were mapped within nucleotide positions 458 to 473 for the 5 end and nucleotide positions 559 to 594 for the 3 end, respectively. Thus we conclude that a 136-base-pair fragment corresponding to the second half of the R region was sufficient to allow elevation of the level of gene expression.     

老年腹股沟疝患者疝环充填式无张力修补术86例

目的总结弛环充填式无张力修补术治疗老年腹股沟疝患者的经验。方法回顾分析2002年3月-2005年7月采用德国Braun公司生产的Braun mesh和plug治疗的86例老年腹股沟疝患者的临床资料。结果平均手术时间35min，术后8-10h下床活动，2周恢复日常生活，伤口均一期愈合，术后尿潴留15例，异物感3例，随访3—40个月无一例复发。结论疝环充填式无张力修补术操作方便，创伤小，恢复快，复发率低，是老年患者理想有效的疝修补术。     

颅内海绵状血管瘤 CCM1基因第12外显子及其5′端内含子新突变位点

目的　探讨 CCM1基因突变在中国人颅内海绵状血管瘤 ( intracranial cavernous angiomas,ICCA)发病中所起的作用。方法　收集我院神经外科 2 0 0 2年 6月～ 2 0 0 3年 2月收治并经手术病理证实的2 1例 ICCA患者及 15名正常健康对照者 ,从外周静脉血中提取 DNA,PCR法扩增 CCM1基因第 12外显子及其两侧部分内含子序列 ,应用 DNA直接测序技术对扩增产物进行检测。结果　 5例患者中检测出 3处 CCM1基因突变 ,均为首次发现。其中 ,5例患者中均存在 1172 C→ T的错义突变 ,使编码 KRIT1蛋白391位的氨基酸由丝氨酸变成苯丙氨酸。另有 1例患者存在 116 0 A→ C的错义突变 ,使编码 KRIT1蛋白387位氨基酸的谷氨酰胺变成脯氨酸。另一个突变发生在第 12外显子 5′端内含子区域 ,5例患者中有 4例第 4个碱基 C被 T取代。对照组检测结果无异常。结论　中国 ICCA患者存在 CCM1基因第 12外显子的突变 ,并与 ICCA的发病有关     

PCR－小卫星DNA指纹图在异基因造血干细胞移植植活指标监测中的应用

为了解异基因骨髓移植治疗某些遗传及恶性血液性疾病的植活监测指标，用聚合酶链式反应（ＰＣＲ）扩增具有高度多态性的小卫星ＤＮＡ３３．１、３３．６位点，联合地高辛标记的位点特异性寡核苷酸探针杂交的方法，以小卫星ＤＮＡ指纹图为特异性遗传标志，对６例异基因骨髓移植，１例脐血移植进行植活指标监测，６例获得供者源性细胞植活证据。结果显示：小卫星ＤＮＡ指纹图个体特异性强，可作为监测异基因造血干细胞移植植活的可靠格标，尤其是同血型，同性别，ＨＬＡ配型表型全相合的移植；该方法程序简单，操作方便，灵敏度高，可达０．５％，最早获得植入证据的时间是＋１５天，仅需模板ＤＮＡ１００ｎｇ；如果扩增位点增加，可提高个体识别能力。     

应用聚合酶链反应技术检测肝组织中的HBV－DNA

采用聚合酶链反应（ＰＣＲ）技术，对４２例肝活切组织石蜡切片中乙型肝炎病毒（ＨＢＶ）ＤＮＡ进行检测，并与乙肝表面抗原（ＨＢｓＡｇ）的免疫组织化学及血清学检测进行比较，ＨＢＶ－ＰＣＲ阳性率为７３．８％，高于组织及血清ＨＢｓＡｇ阳性率（分别为５９．５％和５０．０％）。３例病理形态呈肝炎改变，而血清ＨＢｓＡｇ（─）的肝组织中有２例检出ＨＢＶ－ＤＮＡ，提示ＰＣＲ的高度敏感性和准确性。８３．３％的门脉性肝硬变和８７．５％的肝细胞癌组织中ＨＢＶ－ＰＣＲ呈阳性，进一步证实了上述两病与ＨＢＶ的关系密切。我们还发现肝细胞淤胆患者ＨＢＶ感染率较高，ＨＢＶ－ＤＮＡ及组织ＨＢｓＡｇ阳性比例各为６／９和４／８。     

Evidence that productive rearrangements of TCR γ genes influence the commitment of progenitor cells to differentiate into αβ or γδ T cells

Two models have been considered to account for the differentiation of γδ and αβ T cells from a common hematopoietic progenitor cell. In one model, progenitor cells commit to a lineage before T cell receptor (TCR) rearrangement occurs. In the other model, progenitor cells first undergo rearrangement of TCRγ, δ, or both genes, and cells that succeed in generating a functional receptor commit to the γδ lineage, while those that do not proceed to attempt complete β and subsequently α gene rearrangements. A prediction of the latter model is that TCRγ rearrangements present in αβ T cells will be nonproductive. We tested this hypothesis by examining Vγ2-Jγ1Cγ1 rearrangements, which are commonly found in αβ T cells. The results indicate that Vγ2-Jγ1Cγ1 rearrangements in purified αβ T cell populations are almost all nonproductive. The low frequency of productive rearrangements of Vγ2 in αβ T cells is apparently not due to a property of the rearrangement machinery, because a transgenic rearrangement substrate, in which the Vγ2 gene harbored a frame-shift mutation that prevents expression at the protein level, was often rearranged in a productive configuration in αβ T cells. The results suggest that progenitor cells which undergo productive rearrangement of their endogenous Vγ2 gene are selectively excluded from the αβ T cell lineage.