鲫耳石重量与年龄的关系及其在年龄鉴定中的作用

耳石重量在年龄组间重叠较少,大小相近的个体,年龄大的,即生长慢的耳石重量比年龄小的,即生长快的大,不同龄组之间耳石重量有显著差异（P＜0．05）,按年龄组在耳石重量与相应的体长作图,可初步判断观测年龄的可靠性,分析耳石重量频率分布能分离出体长相近,年龄不同的个体,其结构与耳石年轮观测的基本一致,耳石重量与年龄呈显著线性正相关（P＜0．05）,用耳石重量与年龄关系估算的年龄从耳石上直接读取的年龄无显著差异（P＞0．05）,文中对耳石重量直接用于确定鱼类年龄的可能性作了分析和探讨。     

遗传工程微生物细胞间发生的自然遗传转化

将两株具有不同遗传标记的枯草芽孢杆菌在基本培养基中分别培养至对数生长后期后进行短时间混合静置培养 ,经选择平板筛选、DNaseI敏感性试验、质粒检测和产蛋白酶活性检测 ,发现两菌株之间可通过自然遗传转化进行染色体DNA和质粒DNA的交换。研究结果表明 ,自然遗传转化可在细胞间进行 ,这对揭示微生物群居的自然环境中可能存在的细胞间的DNA转移 ,以及正确评估遗传工程微生物(GEMs)的安全使用具有重要意义。     

The human tRNA(m(2)(2)G(26))dimethyltransferase: functional expression and characterization of a cloned hTRM1 gene

This paper presents the first example of a complete gene sequence coding for and expressing a biologically functional human tRNA methyltransferase: the hTRM1 gene product tRNA(m²₂G)dimethyltransferase. We isolated a human cDNA (1980 bp) made from placental mRNA coding for the full-length (659 amino acids) human TRM1 polypeptide. The sequence was fairly similar to Saccharomyces cerevisiae Trm1p, to Caenorhabditis elegans TRM1p and to open reading frames (ORFs) found in mouse and a plant (Arabidopsis thaliana) DNA. The human TRM1 gene was expressed at low temperature in Escherichia coli as a functional recombinant protein, able to catalyze the formation of dimethylguanosine in E.coli tRNA in vivo. It targeted solely position G₂₆ in T7 transcribed spliced and unspliced human tRNA^Tyr in vitro and in yeast trm1 mutant tRNA. Thus, the human TRM1 protein is a tRNA(m²₂G₂₆)dimethyltransferase. Compared with yeast Trm1p, hTRM1p has a C-terminal protrusion of ~90 amino acids which shows similarities to a mouse protein related to RNA splicing. A deletion of these 90 C-terminal amino acids left the modification activity in vitro intact. Among point mutations in the hTRM1 gene, only those located in conserved regions of hTRM1p completely eliminated modification activity.     

褪黑激素对D-半乳糖处理小鼠学习记忆和脑组织超氧物歧化酶活力的影响

采用Ｍｏｒｒｉｓ水迷宫法和ＮＢＴ法分别检测了褪黑激素对Ｄ－半乳糖处理小鼠的空间学习记忆能力和脑组织超氧物歧化酶活力的影响。结果表明,Ｄ－半乳糖对小鼠的逃避潜伏期无显著影响,但降低小鼠的穿环系数,还促使小鼠的脑组织超氧物歧化酶活力明显升高;褪黑激素可提高小鼠的空间学习记忆能力,降低Ｄ－半乳糖所引起的超氧物歧化酶活力升高。     

Trichosanthin inhibits T cell activation by interfering with the recruitment of ZAP-70 to CD3 ζchain

INTRoDUCTIONThichosanthin(Tk),aplantproteinisolatedfromaChinesemedicinalherbTh-1.Correspondenceaddress:Dr.KuangYenCHoU,ShanghaiInstituteofImmunology,Shang-haiSecondMedicalUniversity28oSouthChongqingRoad,Shanghai2ooo25,China.Fax:(8621)63846383,E-mail:my@sh…     

小麦丛矮病毒NS蛋白基因的克隆及序列分析

利用与Ｎ蛋白ｍＲＮＡ３＇末端顺序相同的２０寡聚核苷酸引物,通过点杂交、限制性内切酶分析从小麦丛矮病毒（ＷＲＳＶ）ｃＤＮＡ文库中筛选到编码Ｎ蛋白基因下游顺序的ｃＤＮＡ克隆。序列分析表明,该ｃＤＮＡ片段含有一编码的４０ｋＤ蛋白的开放读框。将该读框的全长ｃＤＮＡ经ＰＣＲ扩增后,克隆到ｐＧＥＸ－３Ｘ上,在大肠杆菌ＤＥ３中用ＩＰＴＧ诱导表达,经蛋白质印迹鉴定,该基因为小麦丛矮病毒ＮＳ蛋白基因。     

植物叶片衰老过程中叶绿素降解代谢研究进展

 本文对近年植物叶片衰老过程中叶绿素降解代谢研究进展作一介绍,包括叶绿素降解产物分离、检测和命名;叶绿素降解途径及降解酶系。此外,对叶绿素降解意义及今后研究趋势进行了评述。     

Isolation and characterization of five rice telomere-associated sequences

Ｔｅｌｏｍｅｒｅｉｓｔｈｅｅｓｓｅｎｔｉａｌｇｅｎｅｔｉｃｌｏｃｕｓａｔｔｈｅｅｎｄｓｏｆａｌｌｅｕｋａｒｙｏｔｉｃｃｈｒｏｍｏｓｏｍｅｓ.ＴｈｅｙｗｅｒｅｐｒｏｐｏｓｅｄｔｏｃａｐｃｈｒｏｍｏｓｏｍｅｓｐｒｅｖｅｎｔｉｎｇｔｈｅｅｎｄｔｏｅｎｄｆｕｓｉｏｎｓｂｅｔｗｅｅｎｂｒｏｋｅｎｅｎｄｓａｎｄｃｏｎｔｉｎｕａｌｔｅｒｍｉｎａｌＤＮＡｌｏｓｓｄｕｒｉｎｇｒｅｐｌｉｃａｔｉｏｎ.Ｔｈｅｙａｌｓｏｈａｖｅｉｎｆｌｕｅｎｃｅｓｏｎｍｅｍｂｒａｎｅｃｈｒｏｍｏｓｏｍｅｉｎｔｅｒａｃｔｉｏｎａｎｄｔｈｅ…     

Binding of activator SyrM to the site of nodD3 P1 region of Rhizobium meliloti

The nodD3 gene ofRhizobium meliloti is transcribed via promoter P1 or P2. Gel retardation assay showed binding of SyrM to the P1 upstream region of nodD3. DNaseI footprint analysis demonstrated that the binding site of SyrM in nodD3 P1 region consists of two inverted repeat sequences arranged in tandem. SyrM seems to bind to DNA in the form of dimer or tetramer and requires the two inverted repeat sequences for binding. Project supported by the National Natural Science Foundation of China (Grant No. 39370027).     

转基因植物生产动物疫苗的研究及应用

转基因植物生产动物疫苗的研究及应用范国昌１,２山松１钱凯先２沈桂芳１（１．中国农业科学院生物技术研究中心,北京１０００８１）（２．浙江大学生物科学与技术系,杭州３１００２７）ＲｅｓｅａｒｃｈａｎｄＡｐｐｌｉｃａｔｉｏｎｏｎＴｒａｎｓｇｅｎｉｃＰｌａｎ...