尖毛虫属Actin Ⅰ、α-TBP和DNA pol α乱序基因的模式研究

研究旨在对尖毛虫属内现有物种的3种乱序小核基因结构进行比较,探讨其乱序模式。于湛江湖光红树林水域中采集到一个尖毛虫属物种Oxytricha sp.（ZJ）,成功扩增了其肌动蛋白Ⅰ（ActinⅠ）、端粒结合蛋白（α-TBP）、DNA聚合酶α（DNA pol α）3个乱序基因的完整大核基因序列和完整/部分小核基因序列,并结合已有资料对比研究了尖毛虫属这3个乱序基因的进化。结果表明:（1）Oxytricha sp.（ZJ）与O.nova的小核Actin Ⅰ基因具有相同的乱序模式,区别于其余的尖毛虫属物种;在增加尖毛虫属物种的基础上,对前人推测提出了质疑,我们认为MDS-IES接合处移动现象在乱序MDSs之间并非比非乱序MDSs之间更保守。（2）Oxytricha sp.（ZJ）与O.nova的小核α-TBP基因具有相同乱序模式和相似长度的IESs。（3）Oxytricha sp.（ZJ）的小核DNA pol α基因乱序模式,区别于任一已报道物种,与属内O. trifallax最为相近。基于序列分析,在DNA pol α基因中发现了一例IES转换为MDS的痕迹,以及由此导致原先MDS的丢失。研究发现在编码区内IES向MDS的转变,使得本应删除的序列成为基因组永久保留的一部分。     

鳞网衣属1中国新记录种

通过对鳞网衣属地衣形态和化学的研究,并结合核基因ITS序列的系统发育分析,报道了采自中国秦岭山区鳞网衣属1中国新记录种——球鳞网衣(新拟)[Psora globifera(Ach.)A.Massal.]。其识别特征为地衣体由密集、重叠鳞片组成,边缘常上翘,具有光泽,无粉霜,老鳞片上表面常具裂纹;子囊盘微凸至半球形,单一或数个簇生。该研究提供了该种基于中国标本的详细描述,并与相似种进行了比较。     

Discrimination of Repetitive Sequences Polymorphism in Secale cereale by Genomic In Situ Hybridization-Banding

Genomic in situ hybridization banding (GISH-banding), a technique slightly modified from conventional GISH, was used to probe the Chinese native rye (Secale cereale L.) DNA, and enabled us to visualize the Individual rye chromosomes and create a universal reference karyotype of the S. cereale chromosome 1R to 7R. The GISH-banding approach used in the present study was able to discriminate S. cereale chromosomes or segments in the wheat (Triticum aeativum L.) background, including the Triticale, wheat-rye addition and translocation lines. Moreover, the GISH-banding pattern of S.cereale subsp. Afghanicum chromosomes was consistent with that of Chinese native rye cv. Jingzhou rye; whereas the GISH-banding pattem of Secale vavilovli was different from that of S. cereale, indicating that GISH-banding can be used to study evolutionary polymorphism in species or subspecies of Secale. In addition, the production and application of GISH-banding to the study of adenine-thymine-riched heterochromatin is discussed.     

基于叶绿体 Trn L-F 序列和联合数据分析木通科的分子系统发育

基于叶绿体 trn L-F 序列单独分析以及 trn L-F 和 rbc L 序列联合分析重建了木通科的分子系统发育.本研究的系统发育拓扑结构与覃海宁和塔赫他间的族划分系统非常一致.猫儿屎族和串果藤族在系统发育树上位于本科的基部.由分布于南美的勃奎拉藤属和拉氏藤属组成的拉氏藤族得到了 trn L-F 序列分析(100%)和联合序列分析(99%)的很好支持.木通族在两个分析里都得到了100%的靴带支持率.新建立的长萼木通属在 trn L-F 树上嵌套在木通属内;然而,在联合分析的树上,它与木通属形成姐妹群并得到很高的支持率.在系统发育上关系密切的3个属: 牛藤果属、八月瓜属和野木瓜属之间的关系仍未解决.牛藤果与八月瓜在两个分析里都形成姐妹群,但支持率低.小花鹰爪枫嵌套在野木瓜属内,并与西南野木瓜形成姐妹群.木通族内这3个属可能都不是单系,它们的属间界限和属的界定需要更多的分子和形态数据的进一步研究.     

Genetic diversity of Francisella tularensis subspecies holarctica strains isolated in Japan

The recently developed MLVA has high discriminatory power for the typing of individual strains or isolates of Francisella tularensis. In the present study, MLVA was applied to 33 Japanese F. tularensis subspecies holarctica strains to examine the genetic diversity of F. tularensis isolated. Among the seven VNTR loci analyzed, Ft-M2, Ft-M10, and Ft-M20 loci showed high genetic polymorphism in Japanese strains, whereas Ft-M3 was most variable in non-Japanese strains. These results provide novel extended information about the genomic diversity among the strains of F. tularensis ssp. holarctica distributed in Japan and enable determination of whether a given isolate is indigenous to Japan by examining these loci using MLVA.     

A two-stage model for concurrent sequences

Schneider and Davison [Schneider, S.M., Davison, M., 2005. Demarcated response sequences and the generalised matching law. Behav. Proc. 70, 51–61] showed that the generalised matching law applied to concurrent free-operant two-response sequences. When sufficient temporal spacing is required between the responses, however, neither the response-level nor the sequence-level forms of the generalised matching law provide good fits. An alternative “two-stage sensitivity” model with fewer free parameters features two types of sensitivity to the reinforcement contingencies on sequences. When temporal spacing between the responses is long, the “response distribution sensitivity” parameter describes sensitivity only of the individual responses to the sequence-level contingencies. At a threshold level, this sensitivity reaches a maximum. When spacing is shorter than threshold, the “response order sensitivity” parameter reflects a new sensitivity to the order of the responses within sequences. As this sensitivity approaches its maximum, sequence matching is achieved. For both stages, a changeover parameter describes bias against sequences that require changeovers between the two responses. The model fit data ranging from near-response matching with long minimum inter-response times (IRTs) to sequence matching with no minimum IRTs, using two species and a variety of sequence reinforcer distributions. Rats differed from pigeons in achieving sequence matching only at a nonzero minimum IRT. In a comparison based on pigeon data with no minimum IRT, the two-stage sensitivity model was more efficient than the generalised matching law according to the Akaike criterion. The logic of the model suggests a new way of understanding the mechanisms underlying behavioural units.     

A comparison of three molecular typing methods for the discrimination of Salmonella enterica serovar Infantis

Seventy-six epidemiologically unrelated Salmonella enterica serovar Infantis (S. Infantis) isolates were typed by pulsed-field gel electrophoresis (PFGE), multiple amplification of phage loci typing (MAPLT) and multiple-locus variable-number tandem-repeat analysis (MLVA). PFGE, using the restriction endonuclease XbaI, generated 23 different profiles for the 76 isolates (DI=0.848). MAPLT was undertaken using a combination of 11 primer sets based on bacteriophage sequences and generated 28 different profiles (DI=0.938). By contrast, MLVA only produced nine profiles (DI=0.668) with 13 different primer sets, including the five primer sets routinely used for S. Typhimurium typing. Reducing the number of MAPLT primer sets to four still provided a diversity index of 0.838. All three typing methods revealed two distinct lineages of S. Infantis, with most isolates demonstrating genetic traits of either lineage but not both. The results demonstrate that MAPLT can potentially provide greater discrimination and separation of S. Infantis isolates than both PFGE and MLVA. Furthermore, MAPLT data can be generated much more rapidly and with reduced labour input than PFGE and without the need for expensive PFGE electrophoresis equipment, nor does it require capillary sequencing of PCR fragments to accurately determine PCR fragment lengths as is the case with MLVA.