The Effect of the Extracellular Bacteriolytic Enzymes of Lysobacter sp. on Gram-Negative Bacteria

The effect of the extracellular bacteriolytic enzymes of Lysobacter sp. on gram-negative bacteria was studied. These enzymes were found to be able to hydrolyze the peptidoglycan that was isolated from the gram-negative bacteria, the hydrolysis being completely inhibited by the cell wall lipopolysaccharide of these bacteria. The native cells of the gram-negative bacteria became susceptible to the bacteriolytic enzymes after the permeability of the outer membrane of the cells was altered by treating them with polymyxin B.     

Influence of Acidic Exopolysaccharide of Xanthomonas campestris IBPM 124 on the Kinetic Parameters of Extracellular Bacteriolytic Enzymes

Interactions of a negatively charged exopolysaccharide of Xanthomonas campestris IBPM 124 with its extracellular enzymes (muramidase, endopeptidase, and neutral phosphatase) and also with egg lysozyme, lysostaphin, muramidase of Streptomyces globisporus, and a bacteriolytic enzyme complex of Streptomyces albus were studied. All these enzymes were positively charged under the conditions of their maximal activity. It was shown that interaction of the acidic exopolysaccharide from X. campestris with these enzymes changed their kinetic parameters. The change was either positive (increase in reaction rate) or negative (decrease in reaction rate) and depended on the enzyme and type of substrate cleaved. Due to such interactions, the acidic exopolysaccharide secreted by X. campestris into the environment not only retained and transported positively charged exoenzymes into the near-cellular space, but also regulated their activity.     

Specificity of the action of lysoamidase on Staphylococcus aureus 209P cell walls

Specificity of Staphylococcus aureus 209P cell wall hydrolysis by the L1 and L2-bacteriolytic enzymes from lysoamidase lytic complex was studied. L1-peptidase was shown to display both glycyl-glycine endopeptidase and N-acetylmuramyl-L-alanine amidase enzymatic activities on the S. aureus peptidoglycan molecule, whereas L2-peptidase acts as N-acetylmuramyl-L-alanine amidase.     

红色诺卡氏菌细胞壁骨架辅助治疗肿瘤作用的研究个例分析及文献复习

摘要 目的：探究红色诺卡氏菌细胞壁骨架(Nocardia rubra cell wall skeleton, N-CWS)辅助治疗肿瘤作用的研究。方法：在北京协和医院肿瘤内科近5年收治的实体肿瘤患者中,选取愿意接受N-CWS辅助治疗的患者,皮下注射红色诺卡氏菌细胞壁骨架（商品名艾克佳）,200～400 μg/次,每周2次,监测其肿瘤标志物血清癌胚抗原(serum carcinoembryonic antigen, CEA)、影像学及体力状况评分(eastern cooperative oncology group,ECOG评分)等变化,评估N-CWS疗效。结果：病例1加用N-CWS后CEA下降并保持低值4月左右,ECOG评分保持在0~1分。病例2加用N-CWS后CEA下降并维持稳定2月,ECOG 0~1分,患者自觉使用后体力较前好转。病例3在化疗6程后CEA保持最低,并保持稳定1个月。ECOG 保持在0~2分。病例1和病例2的CEA保持稳定的时间长于病例3,且ECOG评分保持低于病例3。结论：使用N-CWS辅助治疗肿瘤,患者CEA水平下降,体力状况改善,显著的改善了患者的症状。     

粉红黏帚霉67-1菌株寄生核盘菌菌核的酶学动态研究

对粉红黏帚霉67-1菌株侵染核盘菌菌核过程的多种细胞壁降解酶活性进行了连续测定,以研究几丁质酶等在这一寄生互作体系中的可能作用。结果表明:葡聚糖酶活性变化表现活跃,且随寄生过程呈增加趋势,配对法T检验结果表明,第10d的处理与对照酶活性差异达到最大;几丁质酶、蛋白酶活性变化表现较低,而纤维素酶未检测得到。酶学动态变化与之前石蜡切片显微观察的结果在时间上表现一致;认为葡聚糖酶可能是粉红黏帚霉67-1菌株寄生核盘菌菌核的关键酶。     

The Geometrical Model for Microfibril Deposition and the Influence of the Cell Wall Matrix

Abstract: A theory for cell wall deposition has been formulated consistent with present day experimental data on cell walls and cellular processes. This theory has a generic origin, geometrical constraints, as the underlying cause for the cell wall architecture. The theory has been worked out as a fully mathematical model, allowing for specific predictions of a qualitative and quantitative nature. The key point of the geometrical theory is the coupling of the trajectory of the cellulose microfibril synthases, i.e., rosettes, to their density. This coupling provides the cell with a mechanism for manipulating the cell wall texture by creating controlled local variations in the number of active synthases. In the present paper we show that the geometrical model can explain the helicoidal, crossed polylamellate, helical and axial wall textures, which are the basic textures found in plant cell walls. In addition, we discuss the role of cortical microtubules in the wall deposition process and how the cell wall matrix contributes to cell wall texture determination.     

Role of a serine-type d-alanyl-d-alanine carboxypeptidase on the survival of Ochrobactrum sp. 11a under ionic and hyperosmotic stress

The plant growth-promoting rhizobacterium, Ochrobactrum sp. 11a displays a high intrinsic salinity tolerance and has been used in this work to study the molecular basis of bacterial responses to high concentrations of NaCl. A collection of Ochrobactrum sp. 11a mutants was generated by Tn 5 -B21 mutagenesis and screened for sensitivity to salinity. One clone, designated PBP and unable to grow on glutamate mannitol salt agar medium supplemented with 300 mM NaCl was selected and further characterized. The PBP mutant carries a single transposon insertion in a gene showing a high degree of identity to the serine-type d -alanyl- d -alanine carboxypeptidase gene of Ochrobactrum anthropi . Interestingly, the expression of this gene was shown to be upregulated by salt in the PBP mutant. Moreover, evidence is presented for the requirement of the gene product for adaptation to high-salt conditions as well as to overcome the toxicity of LiCl, KCl, sucrose, polyethylene glycol (PEG), AlCl₃, CuSO₄, and ZnSO₄. In addition to the altered tolerance to both ionic and osmotic stresses, the PBP mutant exhibited changes in colony and cell morphology, exopolysaccharide production, and an increased sensitivity to detergents.     

Phytoremediation of Cadmium-Contaminated Soils by Young Douglas Fir Trees: Effects of Cadmium Exposure on Cell Wall Composition

Douglas fir trees grown on an artificially Cd-contaminated soil, can tolerate this trace element (up to 68 mg/kg in soil) during several months. Most of the absorbed Cd is retained in roots (25 mg/kg DM), but transfer to aerial part is also effective. Showing the highest content, up to 6 mg/kg DM, among all the aboveground parts, barks seem to be a preferred storage compartment. However, the transfer factor is quite low, about 0.3. Another objective of this study was to compare the cell wall components of trees exposed to increasing Cd amounts in soil. A decrease in lignin and an increase in pectin contents were observed in response to increasing soil cadmium concentration. A concurrent reduction in methyl-esterification of pectin suggests than the structure of this major binding site could therefore be modified as a reaction to cadmium contamination. Future prospects will focus on the modulation of pectin composition in response to Cd exposure.     

产朊假丝酵母细胞壁33 ku蛋白的功能研究

通过胰蛋白酶和枯草杆菌蛋白酶对产朊假丝酵母Candida utilis细胞壁的酶解,发现一种分子质量为33 ku的酵母细胞壁主要结构蛋白. 研究显示,在细胞壁上这种蛋白质与细胞壁绝大多数蛋白质成分不同, 它不被胰蛋白酶水解,但对枯草杆菌蛋白酶的作用敏感.33 ku蛋白存在于酵母菌整个对数生长期的细胞壁中,特别是在对数早期细胞壁中,它是唯一的对胰蛋白酶作用不敏感的蛋白质成分.实验证明,该蛋白质对维系酵母细胞壁骨架成分葡聚糖的相互连接和细胞壁的完整结构,具有重要作用,是一种重要的酵母细胞壁嵌合蛋白.     

The Italian Way to Stem Cell Research: Rethinking the Role of Catholic Religion in Shaping Italian Stem Cell Research Regulations

Stem cell research regulations are highly variable across nations, notwithstanding shared and common ethical concerns. Dominant in political debates has been the so‐called embryo question. However, the permissibility of human embryonic stem cell (hESC) research varies among national regulatory frameworks. Scholars have explained differences by resorting to notions of political culture, traditions of ethical reasoning, discursive strategies and political manoeuvring of involved actors. Explanations based on the role of religion or other cultural structural variables are also employed. This paper analyses the emerging of the Italian regulatory framework on stem cell research using an analytical framework that considers the interplay between cultural structural features, political culture, traditions of ethical reasoning, institutional settings and the discursive and political agency of the actors involved. It aims also to explain the role of Roman Catholic Church in shaping the Italian stem cell research regulation not by treating religion as an autonomous causal factor, but through the analysis of the agency of Catholic and allied actors in the Italian political culture and institutional setting.     

The effect of penicillin on the encystment of Bdellovibrio sp. strain W

When penicillin, and other inhibitors of peptidoglycan synthesis were added to encysting cultures of Bdellovibrio strain W, the encysting process continued, resulting in the production of cysts which were spherical in shape. Transmission electron micrographs of these spherical bdellocysts revealed the absence of an outer cyst wall. These cysts, devoid of cyst wall, were capable of germination under appropriate condition with the emergence from the prey ghost of highly motile spheroplasts. Withdrawl of the antibiotics after encystment had begun led to the production of spherical cysts that were surrounded by an outer cyst wall.     

Hypothesis about the Key Coordinating Role of Adenylyl Cyclase Signaling Mechanism and of cAMP in Regulatory Action of Peptides of the Insulin Superfamily on Fundamental Cellular Processes: Cell Growth, Apoptosis, Metabolism (Development of L.G. Leibson's Heritage)

A new signaling mechanism of action of insulin and other peptides of the insulin superfamily [1—5[, including the following signaling chain: receptor-tyrosine kinase → G_i-protein → phosphatidylinositol 3-kinase → protein kinase C (PKCζ ?) → G_s-protein → adenylyl cyclase → cAMP → protein kinase A, was detected and deciphered, which resulted in the hypothesis about the key coordinating role of this adenylyl cyclase signaling mechanism (ACSM) and cAMP that it produces in regulatory action of these peptides on fundamental processes in the cell. This hypothesis is based on the following assumptions: (1) ACSM and cAMP as the second messengers participate in realization of the mitogenetic, rather than metabolic, action of peptides of the insulin superfamily; (2) ACSM and cAMP are involved in realization of inhibitory effect of insulin and related peptides on processes of cell death (antiapoptotic effect); (3) ACSM and cAMP inhibit metabolic effects of peptides of the insulin nature by preventing their realization. On the basis of these postulates and available facts, our hypothesis can be formulated as follows. The ACSM- produced cAMP acts as the key coordinator and regulator of three simultaneous incompatible cellular processes: cell growth, apoptosis, and metabolism. It is cAMP that determines, at the corresponding stage of action of the insulin-related peptides, the choice of the pathway of transduction of the signal generated by them to coordinatedly initiate one (proliferative) program and switching-off two others that lead to the cell death and to predominance of anabolic processes in the cell. This coordinating role of cAMP can form the basis for the fine regulation of fundamental processes in the cell, which eventually provides cell survival.     

豚草锈菌对三裂叶豚草叶片生理生化特性的影响

【背景】自20世纪50年代三裂叶豚草传入我国以来,迅速蔓延,已给我国农业生产、生态环境、人民健康造成巨大威胁。近年来发现的豚草锈菌对三裂叶豚草有一定的致病性,具备生物防治潜力。【方法】本文利用植物生理学技术研究了豚草锈菌对三裂叶豚草叶片生理生化特性的影响。【结果】锈菌侵染后,三裂叶豚草叶片的相对电导率随病级的增高和侵染时间的延长而上升,说明锈菌破坏了豚草叶片的细胞膜,导致其电解质外渗。同时,发病初期叶片内的丙二醛(MDA)与超氧自由基(O2.-)含量逐渐上升;当发病程度为3级时,O2.-含量达到最高;4级时,MDA含量达到最高。此外,锈菌侵染后,三裂叶豚草叶片抗坏血酸(AsA)含量持续上升,而脯氨酸(Pro)含量在发病后期下降,说明在三裂叶豚草与锈菌互作时,AsA含量虽然增加,但抗性并不明显,而Pro可能具有更为重要的作用。【结论与意义】豚草锈菌的侵入干扰了三裂叶豚草的生理生化反应,这将为深入研究豚草锈菌的致病机理、发挥其生物防治潜力奠定基础。     

Role of Coccophagus sp. in the suppression of the soft green scale Coccus viridis (Green) (Hompoptera: Coccidae) on sapota

The soft green scale Coccus viridis (Green) (Homoptera: Coccidae) has become a major pest of sapota, Manilkara achras (Mill.) Forberg in India. A field study was conducted on the population dynamics of soft green scale Coccus viridis (Green) for 2 years (2004–2006) on sapota at the Indian Institute of Horticultural Research (IIHR) farm, Bangalore, India. The population of green scale declined from 30.72 per leaf in May 2004 to 1.62 per leaf in March 2006. Two coccinellid predators Chilocorus nigrita (Fab.) and Cryptolaemus montrouzieri (Muls.) and one aphelinid parasitoid Coccophagus sp. were recorded on C. viridis. Both the predators played a minor role in the population fluctuation of C. viridis. The parasitoid Coccophagus sp. was the dominant natural enemy observed throughout the study recording a mean of 10.24–94.67% parasitism. A significant positive correlation of the scale population with minimum temperature (r=0.54) and negative relationship with the parasitism by Coccophagus sp. (r=0.81) was recorded. Multiple regression analysis revealed that 75.7% of the variation present in the green scale population could be predicted by abiotic factors and parasitism by Coccophagus sp. Further, step-wise regression procedure employed to arrive at a multiple regression model showed that about 65.60% of the scale population could be predicted by one factor namely, parasitism by Coccophagus sp. These results showed that parasitism by Coccophagus sp. played a major role in regulating the population of the soft green scale infesting sapota.     

Effects of media composition on submerged culture spores of the entomopathogenic fungus,Metarhizium anisopliae var. acridum Part 2: Effects of media osmolality on cell wall characteristics,carbohydrate concentrations,drying stability,and pathogenicity

This study evaluates osmolality of a submerged conidia-producing medium in relation to the following spore characteristics: yield, morphology (dimensions and cell wall structure), chemical properties of cell wall surfaces (charge, hydrophobicity, and lectin binding), cytoplasmic polyols and trehalose, and performance (drying stability and pathogenicity). Spore production was increased by the addition of up to 150 g l^?1 polyethylene glycol 200 (PEG). Spores from high osmolality medium (HOM spores) containing 100 g l^?1 PEG had thin cell walls and dimensions more similar to blastospores than submerged conidia or aerial conidia. However, a faint electron-dense layer separating primary and secondary HOM spores’ cell walls was discernable by transmission electron microscopy as found in aerial and submerged conidia but not found in blastospores. HOM spores also appeared to have an outer rodlet layer, unlike blastospores, although it was thinner than those observed in submerged conidia. HOM spores’ surfaces possessed hydrophobic microsites, which was further evidence of the presence of a rodlet layer. In addition, HOM spores had concentrations of exposed N-acetyl-β-d-glucosaminyl residues intermediate between blastospores and submerged conidia potentially indicating a masking of underlying cell wall by a rodlet layer. All spore types had exposed α-d-mannosyl and/or α-d-glucosyl residues, but lacked oligosaccharides. Similar to blastospores, HOM spores were less anionic than submerged conida. Although HOM spores had thin cell walls, they were more stable to drying than blastospores and submerged conidia. Relative drying stability did not appear to be the result of differences in polyol or trehalose concentrations, since trehalose concentrations were lower in HOM spores than submerged conidia and polyol concentrations were similar between the two spore types. HOM spores had faster germination rates than submerged conidia, similar to blastospores, and they were more pathogenic to Schistocerca americana than submerged conidia and aerial conidia.     

The biology of the phonotactic parasitoid, Homotrixa sp. (Diptera: Tachinidae), and its impact on the survival of male Sciarasaga quadrata (Orthoptera: Tettigoniidae) in the field

Abstract.

• 1 Unlike most parasitoids, tachinid flies of the tribe Ormiini use sound to locate their hosts. Although thought to exert selection pressure on their host's calling behaviour, little is known about the biology of ormiines. Accordingly, this study reports the biology and impact of the ormiine Hornotrixa sp. upon calling males of the univoltine bushcricket Sciarasaga quadrata Rentz in south-western Australia.
• 2 Populations of adult S.quadrata were monitored in the field over two successive calling seasons. Females, which do not call, were not parasitized by Hornotrixa sp., but the risk of parasitism for males increased as the 3-month calling season progressed. Parasitism did not commence until c. 2 weeks into the calling season, but by the end of the season up to 87% of surviving males were parasitized.
• 3 Parasitized males lived for 14 days and were found singing until their penultimate evening before death in the field. Unparasitized males lived on average 69 days and a maximum of 119 days.
• 4 Multiparasitism of hosts was common, with up to sixteen fly larvae found within parasitized males. The number of fly larvae within hosts significantly increased at the end of the season. However, successful emergence of fly larvae from hosts, as well as pupal size, significantly decreased as more than one fly larva developed within the host.
• 5 Hornotrixa sp. has a long pupal duration of 30–31 days at 20°C. As a consequence, only one complete fly generation, which overwinters in the pupal stage, is likely within each host generation.
• 6 No evidence for differential (size-bias) mortality by Hornotrixa sp. on male S.quadrata was found. The size of parasitized and unparasitized males collected in the field was not significantly different.
• 7 It is concluded that Hornotrixa sp. is a significant mortality factor acting on the survival of adult male S.quadrata.