Temperature dependence of the transition enthalpy of core particle DNA and of long DNA

The denaturation of short (145 base pairs) and long (about 8000 base pairs) DNA moelucules has been studied by adiabitic differential microcalorimetry in solutions with different NaCl content. It is found that the enthalpy of denaturation of short DNA is more sensitive to changes in T_m than that of long DNA. A comparison with other data is also given.     

水稻条纹叶枯病毒分子生物学的研究——Ⅲ.外壳蛋白基因的序列分析

以含有水稻条纹叶枯病毒(RSV)外壳蛋白(CP)基因的重组克隆为材料,将RSV-cDNA酶解后,亚克隆人M13mp18、19,采用双脱氧链终止法测序得到RSV-CP基因的全长序列(共含966bp),同日本已发表的RSV-CP基因序列相比同源率达97％。     

黑胸大蠊（Periplaneta fuliginosa）病毒的分离及某些特性

从黑胸大蠊(Periplaneta fuliginosa)自然罹病的虫尸中分离得到一株非包涵体病毒。将病毒悬液均匀拌入无菌饲料并供食154～169日龄黑胸大蠊健康若虫时,能使其感染、发病,死亡率可达98％以上。在电子显微镜下观察时,病毒为球形二十面体颗粒,直径约23nm。病毒悬液具有典型核蛋白紫外吸收光谱。病毒用DNase和RNase处理并经吖啶橙染色、二苯胺和苔黑酚试验及甲醛反应证明:该病毒含有单链DNA。以上特性与细小病毒科的特征有点类似。     

正常人及不育者精子核DNA的定量研究

用流式细胞术,Feulgen显微分光光度法,荧光显微分光光度法测定正常人精子核DNA相对含量:结果表明,上述方法所测得的精子核DNA相对含量稳定,变化范围小。同时用Feulgen显微分光光度法测定不育者精子核DNA相对含量。显示不育者精子核DNA相对含量高于正常人,提示精子核DNA核蛋白复合物异常可能是某些男性不育症的原因。此项研究为诊断男性不育症提供了新方法,在男性学精子核分子研究方面提供了依据。     

荧光显微镜观察大蒜油对腹水癌细胞的影响

用吖啶橙染色,荧光显微镜观察大蒜油对—S180,昆明小鼠,U14 C57BL/6J小鼠和L1210DBA小鼠的癌细胞作用的影响,结果表明大蒜油有直接破坏癌细胞的DNA,RNA和分裂中期染色体的作用。给药后2—6小时作用最强,12小时后癌细胞数逐渐恢复,因此给药间隔不应超过12小时。我们研究证实大蒜油有明显的抗癌作用,为临床应用提供有力的依据。     

双拷贝人α型心钠素基因的组建及大肠杆菌分泌型克隆与表达

将单拷贝人α心钠素基因3′端用Ban Ⅱ酶解除去包括终止密码在内的36个碱基对,代之以人工合成的含Glu-Lys-Phe-Glu连接片段与另一单拷贝人α心钠素基因的5′端串连成编码60肽的双拷贝心钠素基因,克隆于大肠杆菌分泌型表达载体pIN-Ⅲ-OmpA_2质粒中,表达生成60肽的双拷贝人α型心钠素衍生物,在信号肽的作用下分泌至胞膜间质并自动切割为60肽的外源基因产物。分子量约8K的表达产物用分子筛或超滤膜分离后再经HPLC纯化,表达产物具有明显的心钠素放免活性和舒张血管活性。     

人参多肽基因的酶法体外随机——定位诱变

本文报道了酶法体外随机——定位诱变人参多肽基因的原理和方法。该法把传统的随机诱变和现代的定位诱变融合起来,可灵活控制基因突变的随机性和定位性。我们用双脱氧末端终止法测定了三个突变株的结果证实了该法的合理性和可行性,     

寡聚脱氧核苷酸d(G-C)_3的激光喇曼谱及其分析

用改进的固相磷酰三酯法合成了oligo-d(G-C)_3。以氩离子激光为激发光源,波长488nm.,在室温条件下,分别测定了纯化后的oligo-d(G-C)_3和其组分单体5’-dGMP和5’-dCMP的激光喇曼谱。观察到被测定的物质在300-2500cm~(-1)频率区间,各自都有其特征的谱形和喇曼峰。5’-dGMP和5’-dCMP谱中大多数特征峰在寡聚体的谱中消失,而在oligo-d(G-C)_3谱中出现了几处新的喇曼峰。经查证,峰832,851和899cm~(-1)系糖-磷酸主链的特征喇曼峰,另外几处峰与DNA的构象有关。实验结果表明oligo-d(G-C)_3在水溶液中(室温)主要以B-构象存在。     

A direct approach to the measurement of genetic variation in fish populations: applications of the polymerase chain reaction to studies of Atlantic cod, Gadus morhua L.

We used the polymerase chain reaction (PCR) and direct DNA sequencing to study genetic variation within and among populations of Atlantic cod, Gadus morhua , in the western North Atlantic. In a 307 bp region of the mitochondrial cytochrome b gene, 24 variable nucleotide positions define 24 genotypes, which differ by from one to six nucleotide substitutions. Greenland cod ( G. ogac ) differs from the most similar G. morhua genotype by an additional 12 nucleotide substitutions. Silent transitions dominate both intra- and interspecific comparisons, however four nucleotide substitutions within morhua result in amino acid replacements. Direct sequencing of DNA reveals substantially more of the genetic variation that exists within and between species than do previous indirect methods based on restriction fragment length polymorphisms, and thus has far greater potential to quantify such differences as may exist among fish stocks. Preliminary experiments also indicate that automation of DNA sequencing provides an efficient, rapid, and accurate means for detection of genetic variation in natural populations offish.     

Spawning patterns in the three-spined stickleback (Gasterosteus aculeatus L.): an evaluation by DNA fingerprinting

We analysed a random sample of 10 three-spined stickleback nests by DNA fingerprinting. DNA from the guardian male and a random subsample of LO fry per nest were probed with pYNZ 132, a human single-locus probe for VNTR-loci (variable number of tandem repeats). On average this probe produced DNA fingerprints of 12 scoreable bands. By comparing the bands present in each individual, we calculated band sharing indices (BSIs) between the guardian male and its fry. The BSls varied between 0.40 and 0.77 with an average (± S.D.) of 0.59 ± 0.09. We therefore conclude that the guardian male was the true father of the fry in all these nests. Once the paternal bands in each fry were determined, we compared the maternal bands among the fry of each nest. Based on the BSIs obtained with these comparisons, we found that one guardian male enticed three females to spawn in its nest, six enticed two females and three enticed one female.