宁夏沙坡头地区中国新记录地衣（英文）

报道了宁夏沙坡头沙漠地区地衣3个中国新记录种:Fulgensia desertorum,Rinodina bischoffii和Seirophora orientalis,描述了3种地衣的表型特征,生态学特征及分布情况。     

云南茶树上的附生地衣

对云南茶叶农场中的附生地衣进行调查发现: 附生在茶树上的地衣有25 属, 51 种; 其中, 45 种是首次报道附生在茶树上, 包括2 个中国新记录种: 癞屑衣( Lepraria lobificans) 和阿曼原胚衣( Protoblastenia amagiensis) , 以及20 个云南新分布种。壳状地衣的共生菌丝侵入茶叶树干外皮层组织, 在生长过程中产生地衣酸, 一定程度的加速了农场中茶树的老化; 靠近茶树发芽点生长的壳状地衣和叶状地衣, 造成芽体发育不良, 对茶叶的产量和品质有一定影响。     

Pygo基因的细胞定位及其在果蝇发育过程中的表达(英文)

Wingless信号传导是果蝇胚胎和幼虫发育过程中的一个关键性的信号传导通路。已鉴定出来许多参与Wg Wnt信号传导的Wg或其脊椎动物同源基因Wnt下游传导通路的基因。Wg下游的Wg信号传导是由核TCF LEF 1通过Armadillo (Arm) β catenin介导的。pygopus (pygo)是一个最近发现的Wg Wnt信号传导通路新成员。通过细胞定位实验发现pygo专一性的表达在细胞核中。运用反义mRNA作探针的原位杂交技术 ,观察到了pygo基因在果蝇胚胎中的表达特性。虽然pygo普遍表达于果蝇胚胎发生全过程 ,但pygo在前囊胚层 (pre blastoderm)中的表达水平相对较高 ,这说明胚胎发生过程中来自母方的贡献较高。在幼虫组织 (包括翅成虫盘 ,眼成虫盘和腿成虫盘 )的发育过程中 ,pygo的表达水平总的来说比较低。然而 ,比较翅成虫盘 ,眼成虫盘和腿成虫盘的pygo表达水平 ,则在翅成虫盘和腿成虫盘pygo的表达水平相对较高。     

The discrimination of roach Rutilus rutilus (Linnaeus, 1758) populations in different parts of a river system. An investigation using biochemical markers

Roach populations from different parts of the network of the French Upper Rhone and from Lake Geneva were examined. Several populations were discriminated by the electrophoresis of 16 enzymes coded for by 28 gene loci. 90% of the overall genetic variation was due to intrapopulation variation. Some affinity was found between the populations of Lake Geneva and the Rhone immediately downstream, but the stocks of the Rhone farther down proved to be clearly distinct from these (genetic distance D = 0.048) and probably included several independently reproducing populations. One of these populations was only found in the channel, others inhabited a side arm (D between them = 0.035) or succeeded each other in it, presumably in connection with spawning migrations.     

Transformation of a conditionally peptidoglycan-deficient mutant of Staphylococcus aureus with plasmid DNA.

A simple and reliable method for polyethylene glycol-induced plasmid transformation of a temperature-sensitive peptidoglycan-deficient mutant of Staphylococcus aureus is described. The procedure uses strains carrying the tofA372 mutation grown under conditions that yield osmotically fragile cells capable of efficient wall regeneration. The peptidoglycan-deficient cells were transformed with plasmids pE194 and pI258 at frequencies comparable with those obtained with protoplasts prepared with lysostaphin treatment. A readily portable tofA372 mutation was constructed by isolating an insertion of the erythromycin resistance transposon Tn551 adjacent to tofA372. tofA372 was shown by protoplast fusion and transformation analyses to be in the gene order hly-421-omega [Chr::Tn551]1059-tofA372-uraB232-omega [Chr::Tn916]1101-thrB106 on the chromosome of S. aureus NCTC 8325.     

Genetic transformation in Staphylococcus aureus: demonstration of a competence-conferring factor of bacteriophage origin in bacteriophage 80 alpha lysates.

A virion component that is responsible for conferring competence to Staphylococcus aureus was demonstrated in lysates of bacteriophage 80 alpha, a serological group B phage. Isolated particles of 80 alpha could not be shown to confer significant levels of competence. The phage component had a density of about 1.3 g/cm3, was inactivated by pronase, and was inhibited by antiserum prepared against isolated infectious particles of a serological group B phage. Centrifugation through a Ficoll gradient resulted in separation of competence-conferring activity and plaque-forming units. It is concluded that this proteinaceous subvirion component constitutes a bona fide competence factor of bacteriophage origin.     

Distribution of Tn551 insertion sites responsible for auxotrophy on the Staphylococcus aureus chromosome

A method was devised to efficiently select isolates of Staphylococcus aureus 8325 in which Tn551, a transposon originating on the pI258 plasmid responsible for erythromycin resistance (Emr), had translocated to the host chromosome. This method consisted of selecting for Emr at 43 degrees C with a strain in which the pI258 plasmid was unable to replicate at 43 degrees C because of a temperature-sensitive plasmid mutation. By selecting isolates that were Emr at 43 degrees C and auxotrophic for nutrients not required by the parent strain. Tn551-induced auxotrophic mutants were readily isolated. The incidence of auxotrophic classes was not random; 80% of the isolates in one experiment were Trp-, whereas only a single example of each of some of the other classes was isolated. Among the Trp- mutants, the distribution of trp genes affected and the frequency of precise excision of Tn551 from individual sites varied. When analyzed by transformation, the Tn551-induced ala, his, ilv, lys, rib, thrA, thrB, and trp mutations were shown to occupy sites previously defined by nitrosoguanidine-induced mutations. Tn551-induced mutagenesis provided three previously unrecognized classes of auxotrophs (tyr, met, and thrC), and the Tn551 integration sites resulting in these mutations have been identified. In addition, a chromosomal region (uraB) was identified by Tn551 mutagenesis that is distinct from uraA (previously defined by chemical mutagenesis). Some Tn551-induced mutations (most notably pur) could not be linked to the known linkage groups of the chromosome by transformation. With the exception of two pur mutations, all of the Tn551-induced auxotrophic mutational sites cotransformed at unity with Tn551 and, in cases in which they were selected, prototrophic transformants were always Ems. Thus, the Tn551 and auxotrophic sites are identical.     

Genetic transformation in Staphylococcus aureus: isolation and characterization of a competence-conferring factor from bacteriophage 80 alpha lysates.

The competence-conferring activity in crude lysates of the staphylococcal bacteriophage 80 alpha was concentrated and purified by (NH4)2SO4 precipitation, differential ultracentrifugation and rate-zonal centrifugation through Ficoll. This concentrated preparation exhibited lytic activity toward assay cells of Staphylococcus aureus 8325-4 that could not be attributed to the residual 80 alpha infectious particles present. Electron microscopic examination of the concentrated competence-conferring activity revealed an occasional intact but empty virion and large numbers of free phage tails. Sodium dodecyl sulfate-polyacrylamide gel analysis of this material confirmed that the competence-conferring activity contained only some, but not all, of the major virion proteins. The competence-conferring activity exhibited single-hit kinetics when assay cells and 80 alpha transfecting deoxyribonucleic acid were present in excess. The competence-conferring activity thus seems to be a unique morphogenic precursor of the 80 alpha virion that mediates transfection and transformation in the presence of 0.1 M CaCl2.     

Identification of a chromosomal determinant of enterotoxin A production in Staphylococcus aureus.

Chromosomal mapping of the determinants for enterotoxin A and enterotoxin B production in three strains of Staphylococcus aureus was attempted by using conventional transformation procedures and a series of multiply marked derivatives of NCTC 8325 as recipients. A gene governing enterotixin A production (entA+) in strain S-6 was located on the chromosome between the pur-110 and ilv-129 markers, very close to a determinant of alpha-hemolysin production, hla+. The entA+ gene of strain FRI-196E was shown not to be located at the same position; its location could not be determined. The entB+ genes of strains S-6 and C243 were not located within the known linkage groups examined. Recombinants were screened for enterotoxin production by a new procedure that combined characteristics of immune serum plate and optimal sensitivity plate procedures. The strains and methods used in this study of enterotoxin determinants should prove useful in genetic studies to locate other chromosomal determinants of S. aureus whose phenotypes are difficult to score or select for.