让它们走出牢笼

动物园里展示的动物,是它们野生同伴的“使者”,为了人类的需要,来到这钢筋水泥的城市,如何使这些“使者”在委屈之中也能得到一些快乐,是动物园一件做不完的事情。[编者按]     

Influence of magnesium ions on biofilm formation by Pseudomonas fluorescens

Mg²⁺ can potentially influence bacterial adhesion directly through effects on electrostatic interactions and indirectly by affecting physiology-dependent attachment processes. However, the effects of Mg²⁺ on biofilm structure are largely unknown. In this study, Pseudomonas fluorescens was used to investigate the influence of Mg²⁺ concentration (0, 0.1 and 1.0 mM MgCl₂) on biofilm growth. Planktonic and attached cells were enumerated (based on DAPI staining) while biofilm structures were examined via confocal laser scanning microscopy and three-dimensional structures were reconstructed. Mg²⁺ concentration had no influence on growth of planktonic cells but, during biofilm formation, Mg²⁺ increased the abundance of attached cells. For attached cells, the influence of Mg²⁺ concentration changed over time, suggesting that the role of Mg²⁺ in bacterial attachment is complex and dynamic. Biofilm structures were heterogeneous and surface colonization and depth increased with increasing Mg²⁺ concentrations. Overall, for P. fluorescens, Mg²⁺ increased initial attachment and altered subsequent biofilm formation and structure.     

Enzymatic properties and identification of a fibrinolytic serine protease purified from Bacillus subtilis DC33

A novel fibrinolytic enzyme subtilisin FS33 was purified from Bacillus subtilis DC33, isolated from a traditional flavour-rich food in China. The purified subtilisin FS33 was a single chain protein with a molecular mass of 30 kDa measured by SDS-PAGE. After activated SDS-PAGE, the enzyme band exhibited strong fibrinolytic activity on the fibrin plate. Subtilisin FS33 was temperature-stable below 60°C over the pH range 5–12, with a maximum activity at pH 8.0, but the activity completely disappeared after 10 min above 65°C. The NH₂-terminal amino acid sequence of the enzyme was different from that of other known fibrinolytic enzymes, such as NK, CK, SMCE, KA38, subtilisin E, subtilisin DFE and Katsuwokinase. The amidolytic activities of subtilisin FS33 were inhibited completely by phenylmethanesulfonyl fluoride (PMSF) and soybean trypsin inhibitor (SBTI). EDTA did not affect the enzyme activity, and none of the ions tested activated the activity. Therefore, the enzyme was thought to be a subtilisin-like serine protease. The enzyme degraded the Bβ-chains of fibrin(ogen) very rapidly and then degraded the Aα-chain and at least five fragments from fibrin(ogen) were obtained after hydrolysis. Subtilisin FS33 was also able to cleave blood clots in the absence of endogenous fibrinolytic factors.     

A Na+/H+ antiporter gene of the moderately halophilic bacterium Halobacillus dabanensis D-8T: cloning and molecular characterization

A gene encoding a Na(+)/H(+) antiporter was cloned from a chromosomal DNA of Halobacillus dabanensis strain D-8(T) by functional complementation. Its presence enabled the antiporter-deficient Escherichia coli strain KNabc to survive in the presence of 0.2 M NaCl or 5 mM LiCl. The gene was sequenced and designated as nhaH. The deduced amino-acid sequence of NhaH consists of 403 residues with a calculated molecular mass of 43,481 Da, which was 54% identical and 76% similar to the NhaG Na(+)/H(+) antiporter of Bacillus subtilis. The hydropathy profile was characteristic of a membrane protein with 12 putative transmembrane domains. Everted membrane vesicles prepared from E. coli cells carrying nhaH exhibited Na(+)/H(+) as well as Li(+)/H(+) antiporter activity, which was pH-dependent with highest activities at pH 8.5-9.0 and at pH 8.5, respectively. Moreover, nhaH confers upon E. coli KNabc cells the ability to grow under alkaline conditions.     

体外培养的小梁细胞表达水通道蛋白-1

目的观察体外培养条件下的牛眼小梁细胞(bovine trabecular meshwork cell,BTMC)是否表达水通道蛋白-1(Aquaporin-1,AQP-1)。方法采用免疫组织化学方法检测AQP-1在BTMC上的表达,并进行半定量分析。结果正常BTMC可见AQP-1蛋白表达,其灰度值为:167.94±1.18;阴性对照为:195.64±1.62,统计学分析其差异具有显著性(P<0.05)。结论在体外培养条件下,BTMC表达AQP-1,这有助于在体外条件下研究房水流出阻力、并探讨青光眼的药物治疗。     

一例特殊inv(Y)形成机理的研究

应用双色荧光原位杂交的方法,国内首次报道一例特殊inv(Y)异常的性质,探讨Y染色体倒位结构异常的形成机理以及与习惯性流产临床表型的关系。应用 Biotin-11-dUTP标记的Y染色体短臂断裂点Yp11.3探针（编号889）和CY3标记的Y染色体长臂断裂点Yq12远端异染色质区探针(编号PY3.4),对1例G显带核型分析为[46, XY(90%) / 46, X, inv(Y)(p11.3;q12)]的平衡易位携带者进行双色荧光原位杂交研究。双色FISH结果显示,该易位携带者异常核型比例为22%,稍高于G显带分析中确定的比例。而且,除G显带检测出的倒位类型外,又有两种类型的倒位,其中涉及到常规显带技术难以检测出的染色单体型倒位。3种倒位类型的存在说明该患者inv(Y)断裂点呈不均一性。FISH技术是一种能准确可靠检测出染色体倒位形成的重要手段。      

A high-throughput method for genotyping S-RNase alleles in apple

We present a new efficient screening tool for detection of S-alleles in apple. The protocol using general and multiplexed primers for PCR reaction and fragment detection on an automatized capillary DNA sequencer exposed a higher number of alleles than any previous studies. Analysis of alleles is made on basis of three individual fragment sizes making the allele interpretation highly accurate. The method was employed to genotype 432 Malus accessions and exposed 25 different S-alleles in a selection of Malus domestica cultivars of mainly Danish origin (402 accessions) as well as a selection of other Malus species (30 accessions). The allele S3 (28 %) was the most common among the Danish cultivars followed by S1 and S7 (both 27 %). The alleles S36 and S40 not previously reported from M. domestica were found in 6 and 17 cultivars, respectively. Complete allelic composition was found in 91 % of the 369 diploid accessions and in 86 % of the 63 triploids concerned. We further identified a relatively high frequency of S33 and S34, which has not been considered by most previous studies. The protocol presented here is easy to adopt and saves both time and work effort compared to previous methods. The robustness is illustrated by the great accuracy and a high number of S-alleles presented.     

The Thyrotropic Cell in the Atlantic Salmon,Salmo salar

The thyrotropin (TSH) producing cells are distributed in the rostral and proximal pars distalis. This cell type is the smallest and most infrequent cell of the adenohypophysis. Its cytology is similar to the smallest gonadotropic (GTH) cells although the two cell types can be separated by the size of the small secretory granules (diameter less than 200 nm) in the TSH cells. In presmolts and smolts the cells are more numerous than in parr and adult salmon and have cytological features indicating an increased activity. This was also the case after intraperitoneal injections of synthetic TRH. Antisera to carp GTH and salmon GTH cross-reacted with both the GTH and the TSH cells. Anti-human TSH cross-reacted only with the TSH cells which confirms the assumption of antigenic similarity between human and fish TSH.     

青枯病生防菌ANTI-8098A菌株发酵过程氨基酸变化动态的研究

青枯病生防菌ANTI- 80 98A发酵过程的氨基酸测定结果表明 :ANTI - 80 98A的氨基酸代谢消耗发生在 0～ 2 4h ,消耗了 87.0 7%的总氨基酸 ;代谢累积发生在 2 4～ 4 8h ,4 8h的总氨基酸为 0h的 1 .6 7倍。在 1 7种测定的氨基酸中 ,1 6种氨基酸都表现出与总氨基酸类似的变化趋势 ,丝氨酸在 32h有最大值 ;根据含量大小可分为 3类 ,根据变异系数大小也可分为 3类 ,其中谷氨酸含量 ,丝氨酸变异系数最大。氨基酸种类特性的聚类分析结果表明 :当λ =1 7.5 0时 ,氨基酸变化可分为 4大类。发酵时间的聚类分析结果表明 :当λ=2 5 .36时 ,可分为 3大类 ,与总氨基酸的变化相关