On the precision and accuracy achieved by Escherichia coli cells at fission about their middle

Length and width of each of the prospective siblings of constricted Escherichia coli cells from different strains and culture conditions were measured from electron micrographs. The data were statistically analyzed to investigate how equally the length and volume of one cell was divided into two. The analysis showed that, for all cultures, bipartition is unbiased or very nearly so, i.e. sibling cells were on the average equally long and large. The precision of bipartition attained by the cells was usually high; it was related to the average cell shape (length/width): slender E. coli cells divided into two less precisely than squat cells. Absolute size, growth rate and strain specificity affected the precision of bipartition only indirectly, i.e. in as much as they influenced cell shape.     

Separation and analysis of free ceramides containing 2-hydroxy fatty acids in Sphingobacterium species

Abstract The occurrence of free ceramides was shown in the chloroform-methanol extractable lipids of 16 strains of Sphingobacterium including three species: S. versatilis, S. multivorum and S. mizutae . The predominant long-chain base was identified as a branched-chain, saturated dihydroxy base with a carbon chain consisting of 17 carbon atoms, while the most abundant fatty acid was 2-hydroxy-13-methyltetradecanoic acid. The major molecular species of the intact ceramides were identified as LCB- d - iso -17 : 0-2-OH iso -15 : 0FA, LCB- d - iso -17 : 0- iso -15 : 0FA and LCB- d -n16 : 0- iso -15 : 0FA.     

Retention of bacteria on a substratum surface with micro-patterned hydrophobicity

Bacteria adhere to almost any surface, despite continuing arguments about the importance of physico-chemical properties of substratum surfaces, such as hydrophobicity and charge in biofilm formation. Nevertheless, in vivo biofilm formation on teeth and also on voice prostheses in laryngectomized patients is less on hydrophobic than on hydrophilic surfaces. With the aid of micro-patterned surfaces consisting of 10-microm wide hydrophobic lines separated by 20-microm wide hydrophilic spacings, we demonstrate here, for the first time in one and the same experiment, that bacteria do not have a strong preference for adhesion to hydrophobic or hydrophilic surfaces. Upon challenging the adhering bacteria, after deposition in a parallel plate flow chamber, with a high detachment force, however, bacteria were easily wiped-off hydrophobic lines, most notably when these lines were oriented parallel to the direction of flow. Adhering bacteria detached slightly less from the hydrophilic spacings in between, but preferentially accumulated adhering on the hydrophilic regions close to the interface between the hydrophilic spacings and hydrophobic lines. It is concluded that substratum hydrophobicity is a major determinant of bacterial retention while it hardly influences bacterial adhesion.     

Vertical distribution of bacterial community structure in the sediments of two eutrophic lakes revealed by denaturing gradient gel electrophoresis (DGGE) and multivariate analysis techniques

Vertical distribution of bacterial community structure was investigated in the sediments of two eutrophic lakes of China, Lake Taihu and Lake Xuanwu. Profiles of bacterial communities were generated using a molecular fingerprinting technique, denaturing gradient gel electrophoresis (DGGE) followed by DNA sequence analysis, and the results were interpreted with multivariate statistical analysis. To assess changes in the genetic diversity of bacterial communities with changing depth, DGGE banding patterns were analysed by cluster analysis. Distinct clusters were recognized in different sampling stations of Lake Taihu. Canonical correspondence analysis (CCA) was carried out to infer the relationship between environmental variables and bacterial community structure. DGGE samples collected at the same sampling site clustered together in both lakes. Total phosphorus, organic matter and pH were considered to be the key factors driving the changes in bacterial community composition.     

恢复阴道微生态对复发性老年性细菌性阴道病的疗效观察

目的 探讨用乳酸菌阴道胶囊恢复阴道微生态对提高复发性老年性细菌性阴道病的治愈率,降低复发率的临床疗效观察。方法 120例复发性老年性细菌性阴道病患者随机分成两组,对照组60例,研究组60例。对照组使用甲硝唑联合雌三醇乳膏,连续使用7 d;研究组是在对照组基础上再连续使用乳酸菌阴道胶囊和雌三醇乳膏10 d,停药后一周进行妇科检查及阴道分泌物复查,并对两组症状改善情况进行比较,停药后第1、2、3个月各随访一次,比较两组复发情况。结果 研究组患者临床症状改善情况明显好于对照组,差异有统计学意义（Ps<0.05）。研究组治疗后第1、2、3个月复发率分别为0.00%,5.00%,5.00%,对照组第1、2、3个月复发率分别为11.67%,20.00%,25.00%。研究组复发率明显低于对照组,两组比较Ps<0.05,差异有统计学意义。结论 在复发性老年性细菌性阴道病治疗中给予乳酸菌阴道胶囊恢复阴道微生态,可明显提高治愈率,降低复发率。     

Analysis of bacterial populations in a grassland soil according to rates of development on solid media

Abstract The process of colony formation by bacteria from grassland soil sampled in April, July and September was simulated by a colony-forming curve (CFC). The CFC was a super-imposition of several component curves (cCFC) given theoretically by the first order reaction (FOR) model [3,6]. The pattern of FOR model curves was not influenced by the time of sampling and four cCFCs were always recognized during an incubation period of 160 h. It was considered that the CFC describes an inherent property of the bacterial population of the field. Bacterial isolates were obtained from colonies produced in each of four cCFCs on agar plates. Isolates corresponding to one cCFC were classified as one group. The bacterial isolates were characterized by morphological and physiological tests and subsequently clustered. Few oligotrophic bacteria were obtained among bacteria which produced visible colonies within 63 h of incubation time. On the other hand, approx. 50% of bacteria which produced v colonies after 63 h were oligotrophic bacteria. The time required for the appearance of the first colony, t _r of the FOR model, was very similar in the isolates belonging to one group. A close linear relationship was observed between t _r value and doubling time of isolates.     

北极太平洋扇区海洋沉积物细菌多样性的系统发育分析

对北极太平洋扇区3个不同深度的海洋沉积物样品,采用PCR结合变性梯度凝胶电泳(DGGE)技术进行细菌16S rRNA基因V3区序列的系统发育分析。结果表明,同一个沉积物样品不同层次的DGGE电泳图谱不完全相同。从3个沉积物样品中共获得50条序列,大部分序列与从海洋环境尤其海洋沉积物获得的细菌16S rDNA序列相似性较高(88%~100%),归属于变形细菌(Proteobacteria)的gamma亚群、alpha亚群、beta亚群、epsilon亚群、delta亚群,Cytophaga_Flavobacterium_Bacteroides(CFB)群细菌和高G C含量的革兰氏阳性细菌等系统分类群,其中变形细菌(Proteobacteria)的gamma亚群为沉积物中的优势细菌类群。     

Concerning the dynamic instability of actin homolog ParM

Apoptosis is a highly conserved procedure of cell death and occurs under various stimuli, including oxidative stress. A small heat shock protein, alphaB-crystallin, is found to process resistance to apoptosis in some cells and tissues. But the mechanisms under this protective role are not fully understood. In the present study, we reported the early protective role of alphaB-crystallin against hydrogen peroxide-induced apoptosis in mice myogenic C(2)C(12) cells. alphaB-Crystallin interacted with p53, a proapoptotic protein, during cell apoptosis and such protein interaction mainly occurred in the cytoplasm of the cells, suggesting that the interaction of alphaB-crystallin with p53 might prevent the translocation of p53 from cytoplasm to mitochondria. Hence, this study provides a hint that alphaB-crystallin affects on p53 mitochondrial translocation during oxidative stress-induced apoptosis.