癌基因中的密码子使用

对１９９３年Ｅｎｔｒｅｚ８．０基因库中的癌基因的密码子使用进行了统计分析，给出了家族的归１０００的密码子使用频率，同义密码子使用频率，氨基酸相对丰度，并与非癌普通基因ＰＲＩ（灵长类）进行了比较，结果表明，癌基因与非癌基因对密码子的使用不同，在氨基酸丰度上有差异；各个家族的癌基因对密码子的使用及氨基酸的相对丰度都人特殊性。     

诗中的猛禽——鹘(诗中动物趣谈之七)

上一次给大家介绍了古称“百舌鸟”的乌鸫。这个“鸫”字原来是个废弃的古字，在古文献中都是罕见的，现在却成了现代鸟类学中的常用字。老的字典里还有许多古鸟名，现在已不使用，但在阅读古文献时却常能遇到。“鹘”这种鸟，就是古人在古典诗歌里经常提到的一种猛禽。“鹘”字一字单用时，读为胡（hú）；同别的名词组成双音节词时，读为古（ɡǔ）。古人形容某物飞得极快，常用“疾如鹰隼”这个成语。隼读音为损（sǔn）。鹰隼不是一种鸟，而是两类鸟的合称，一类是鹰类，另一类就是隼类。鹰属鹰科，隼属隼科，二科合为隼形目。鹰和隼最…     

马坝方言词汇

马坝方言词汇林立芳（韶关大学中文系）说明１．本文收录马坝客家方言中较常用的词。先写字后注音，再加注释。２．本文不考本字，无法写出的字用同音字代替，下加波浪线，没有同音字的用方框“口”来代替。３．马坝方言语音系统请参看拙作《马坝方言同音字汇》。（《韶关...     

《史记》中的“莫”

“莫”字在《史记》中共使用407例,其中其他用法43例,而对另外的364例,根据“莫”字的语法功能和所在句子是否有副词、是否有先行词,分为否定性无定指代词和否定副词两类,确定出前者为322例（占总数的88．5％）,后者为42例（占总数的13．5％）,二者的界限往往不太好把握,必须经过细致的分析才能确定其词性。与先秦时文献相比,“莫”字作否定性无定指代词与作否定副词的用例比略高一些,但总体的比例关系没有发生明显变化。     

遵义市高等院校科技工作初探

1 现状 目前，遵义市市内共有高等院校4所，其中，省直属普通高等院校1所（遵义医学院），省属市管普通高：等院校1所（遵义师范学院），市属职业技术学院1所（遵义职业技术学院），市属专科学校1所（遵义医药高等专科学校）。“十五”以来，各高校以邓小平理论、“三个代表”重要思想和党的十六大精神为指导，．认真贯彻落实“科教兴遵”、“可持续发展”和“人才强市”战略，坚持教学与科研并重，教学与科研相互促进的指导思想，在以教学为主，努力提高办学水平和教学质量，为地方经济社会建设大力培养人才的同时，积极利用高等院校人才、技术和科技条件平台等科技资源，围绕促进教学、促进学科建设和服务于地方经济社会发展，     

遗传算法选择操作的递归实现

选择操作是遗传算法中体现“适者生存”的关键一环．最常用的选择方式是“轮盘赌”法．其传统实现建立在逐项比较的基础上，算法复杂度为Ｏ（ｎ２）．通过把各码链适应值转换为一组具有线性序的区间，从而可利用二分查找法实现“轮盘赌”选择操作的递归算法，使时间复杂度下降到Ｏ（ｎｌｏｇ２ｎ）．     

湘方言的“娭（母也）”和客家方言的“（女哀）姐”

“娭（母也）”主要流行于湘方言地区，“（女哀）姐”主要流行于客家话地区。“娭”比较准确地记录了湘方言nai的词音；“（女哀）”是客家人或者说是其他文人专门为客家地区所造的俗字。“（母也）”字较早出现在《方言》中，“姐”字较早出现在《说文》中。“（母也）”和“姐”在早期（汉代或者汉代以前）都是指称母亲。“娭（母也）”和“（女哀）姐”在词源上是同源的。在使用上、意义上、色彩上和地域范围上则有所不同。比较它们的异同，探索它们的源流，分析它们的意义和使用情况，可以加深对“娭（母也）”和“（女哀）姐”的了解。加深对方言称谓词的认识，补充现有字典词典之不足。丰富现代汉语词汇的研究。     

“因”的本义及其在先秦文献里的意义和用法--对《古代汉语》“词的本义和引申义”教学的思考与实例分析

“因”是一个常用汉语词。在先秦文献里，“因”处于虚化过程中，其词性、意义和用法看似十分复杂，但如果明确了“因”的本义为“像垫子（席子）之形”或“会垫子（席子）之意”，则该字的各种意义和用法就如网在纲，纲举目张，十分清晰明确了。     

交流脉冲制备TiO2薄膜的性能研究

利用150kHz交流脉冲放电进行等离子体化学气相沉积（PCVD），使用Ti（OC3H7）4为源物质，在普通钠钙载玻片上制备了TiO2膜．主要考查了交流脉冲电压、反应室工作气压、气体流量、薄膜沉积温度等工艺参数对薄膜光学特性的影响,通过薄膜透过率和吸光度分析，探讨了各工艺参数对成膜品质的影响．结果表明：在载玻片上．根据不同沉积条件可制成性能不同的TiO2薄膜，均有光催化特性且附着力好．     

国务院对学校预防艾滋病教育的要求

1．《中国预防与控制艾滋病中长期规划（1998～2010年）》对学校预防艾滋病健康教育提出了具体工作目标，即“到2002年，普通高等学校和中等职业学校新生入学预防艾滋病、性病健康教育处方发放率达100％；普通初级中学要将艾滋病、性病预防知识纳入健康教育课程，各直辖市、省会城市、计划单列市的学校开课率为100％，县（市）或以上学校的开课率为85％以上，乡（镇）或以下学校的开课率为70％以上”。     

沥青路面养护路段划分方法研究

在路面维修或进行预防性养护时,通常希望同一处置措施的施工路段尽可能长一些,以避免施工机械的频繁迁移.根据实际调查结果,选取横向裂缝长度、纵向裂缝长度、车辙深度和摩擦系数为分类指标,建立聚类分析模型.以Matlab统计工具箱为基础,对路面状况进行聚类分析,以获得该路段的路面破坏主要模式.结果表明,该模型科学简便,评价结果客观、合理,与实际情况符合程度高.     

Genomic organization of the genes encoding mouse T-cell receptor alpha-chain

The vertebrate immune system uses two kinds of antigen-specific receptors, the immunoglobulin molecules of B cells and the antigen receptors of T cells. T-cell receptors are formed by a combination of two different polypeptide chains, alpha and beta (refs 1-3). Three related gene families are expressed in T cells, those encoding the T-cell receptor, alpha and beta, and a third, gamma (refs 4-6), whose function is unknown. Each of these polypeptide chains can be divided into variable (V) and constant (C) regions. The V beta regions are encoded by V beta, diversity (D beta) and joining (J beta) gene segments that rearrange in the differentiating T cell to generate V beta genes. The V gamma regions are encoded by V gamma, J gamma and, possibly, D gamma gene segments. Studies of alpha complementary DNA clones suggest that alpha-polypeptides have V alpha and C alpha regions and are encoded by V alpha and J alpha gene segments and a C alpha gene. Elsewhere in this issue we demonstrate that 18 of 19 J alpha sequences examined are distinct, indicating that the J alpha gene segment repertoire is much larger than those of the immunoglobulin (4-5) or beta (14) gene families. Here we report the germline structures of one V alpha and six J alpha mouse gene segments and demonstrate that the structures of the V alpha and J alpha gene segments and the alpha-recognition sequences for DNA rearrangement are similar to those of their immunoglobulin and beta-chain counterparts. We also show that the J alpha gene-segment organization is strikingly different from that of the other immunoglobulin and rearranging T-cell gene families. Eighteen J alpha gene segments map over 60 kilobases (kb) of DNA 5' to the C alpha gene.     

A yeast gene encoding a protein homologous to the human c-has/bas proto-oncogene product

Organisms amenable to easy genetic analysis should prove helpful in assessing the function of at least those proto-oncogene products which are highly conserved in different eukaryotic cells. One obvious possibility is to pursue the matter in Drosophila melanogaster DNA, which has sequences homologous to several vertebrate oncogenes. Another is to turn to the yeast Saccharomyces cerevisiae, if it contains proto-oncogene sequences. Here we report the identification of a gene in S. cerevisiae which codes for a 206 amino acid protein (YP2) that exhibits striking homology to the p21 products of the human c-has/bas proto-oncogenes and the transforming p21 proteins of the Harvey (v-rasH) and Kirsten (v-rasK) murine sarcoma viral oncogenes. The YP2 gene is located between the actin and the tubulin gene on chromosome VI and is expressed in growing cells. The protein it encodes might share the nucleotide-binding capacity of p21 proteins.     

Preferential utilization of the most JH-proximal VH gene segments in pre-B-cell lines

The most JH-proximal VH gene segments are used highly preferentially to form VHDJH rearrangements in pre-B-cell lines. This result demonstrates that the rate at which immunoglobulin VH gene segments recombine is influenced by their chromosomal organization, and that the initial repertoire of VH genes expressed in pre-B cells is strikingly different from that seen in mature populations.     

Major reorganization of immunoglobulin VH segmental elements during vertebrate evolution

In mammals, the immunoglobulin heavy-chain variable region (VH) locus is organized in a linear fashion; individual VH, diversity (DH), joining (JH) and constant (CH) region segments are linked in separate regions. During somatic development, coding segments flanked by characteristic short recombination signal sequences, separated by intervening sequence regions that may exceed 2,000 kilobases (kb), are recombined. Combinatorial joining of different segments as well as imprecision in this process contribute to the diversity of the primary antibody response; subsequent mutation further alters functionally rearranged genes. This basic somatic reorganization mechanism is shared by six major families of genes encoding antigen receptors. Previously, we have shown that multiple germline genes and mammalian-like recombination signal sequences are associated with the VH gene family of Heterodontus francisci (horned shark), a primitive elasmobranch. Studies presented here demonstrate that segmental reorganization involving mammalian-like DH and JH segments occurs in the lymphoid tissues of this species. In marked contrast to the mammalian system, we find multiple instances of close linkage (approximately 10 kb) between individual VH, DH, JH, and CH segments. This unique organization may limit combinatorial joining and be a factor in the restricted antibody response of this lower vertebrate.     

The DNA sequence and biology of human chromosome 19

Chromosome 19 has the highest gene density of all human chromosomes, more than double the genome-wide average. The large clustered gene families, corresponding high G + C content, CpG islands and density of repetitive DNA indicate a chromosome rich in biological and evolutionary significance. Here we describe 55.8 million base pairs of highly accurate finished sequence representing 99.9% of the euchromatin portion of the chromosome. Manual curation of gene loci reveals 1,461 protein-coding genes and 321 pseudogenes. Among these are genes directly implicated in mendelian disorders, including familial hypercholesterolaemia and insulin-resistant diabetes. Nearly one-quarter of these genes belong to tandemly arranged families, encompassing more than 25% of the chromosome. Comparative analyses show a fascinating picture of conservation and divergence, revealing large blocks of gene orthology with rodents, scattered regions with more recent gene family expansions and deletions, and segments of coding and non-coding conservation with the distant fish species Takifugu.     

A new oncogene in human thyroid papillary carcinomas and their lymph-nodal metastases

Using DNA transfection analysis on NIH 3T3 cells, activated human oncogenes have been isolated from a variety of fresh solid tumours. Thyroid neoplasias show a wide range of lesions varying from slowly progressive well-differentiated tumours to anaplastic highly malignant neoplasms. Therefore they represent an attractive model to investigate the role of oncogene activation in different stages of the neoplastic state. Here we report the detection of transforming activity in DNAs extracted from five thyroid papillary carcinomas and two of their respective lymph-nodal metastases.     

The structure, rearrangement and expression of D beta gene segments of the murine T-cell antigen receptor

It has been postulated that the variable region of the beta-polypeptide of the murine T-cell antigen receptor is encoded by three distinct germ-line gene segments--variable (V beta), diversity (D beta) and joining (J beta)--that are rearranged to generate a V beta gene. Germ-line V beta and J beta gene segments have been isolated previously. Here we report the isolation and characterization of two germ-line D beta gene segments that have recognition signals for DNA rearrangement strikingly similar to those found in the three immunoglobulin gene families and in V beta and J beta gene segments. The D beta and J beta segments can join in the absence of V beta gene segment rearrangement and these rearranged sequences are transcribed in some T cells.     

Human gamma-chain genes are rearranged in leukaemic T cells and map to the short arm of chromosome 7

Three gene families that rearrange during the somatic development of T cells have been identified in the murine genome. Two of these gene families (alpha and beta) encode subunits of the antigen-specific T-cell receptor and are also present in the human genome. The third gene family, designated here as the gamma-chain gene family, is rearranged in murine cytolytic T cells but not in most helper T cells. Here we present evidence that the human genome also contains gamma-chain genes that undergo somatic rearrangement in leukaemia-derived T cells. Murine gamma-chain genes appear to be encoded in gene segments that are analogous to the immunoglobulin gene variable, constant and joining segments. There are two closely related constant-region gene segments in the human genome. One of the constant-region genes is deleted in all three T-cell leukaemias that we have studied. The two constant-region gamma-chain genes reside on the short arm of chromosome 7 (7p15); this region is involved in chromosomal rearrangements identified in T cells from individuals with the immunodeficiency syndrome ataxia telangiectasia and observed only rarely in routine cytogenetic analyses of normal individuals. This region is also a secondary site of beta-chain gene hybridization.