Structural details at active site of hen egg white lysozyme with di- and trivalent metal ions

Metal binding to lysozyme has received wide interest. In particular, it is interesting that Ni2+, Mn2+, Co2+, and Yb3+ chloride salts induce an increase in the solubility of the tetragonal form in crystals of hen egg white lysozyme at high salt concentration, but that Mg2+ and Ca2+ chloride salts do not. To investigate the interactions of the di- and trivalent metal ions with the active site of lysozyme and compare the effects of the di- and trivalent metal ions on molecular conformation of lysozyme based on the structural analysis, the crystal structures of hen egg white lysozyme grown at pH 4.6, in the presence of 0.5 M MgCl2, CaCl2, NiCl2, MnCl2, CoCl2, and YbCl3, have been determined by X-ray crystallography at 1.58 A resolution. The crystals grown in these salts have an identical space group, P4(3)2(1)2. The molecules show no conformational changes, irrespective of the salts used. Ni2+ and Co2+ binding to the Odelta atom of Asp52 in the active site at 1.98 and 2.02 A, respectively, and Yb3+ binding to both the Odelta atom of Asp52 and the Odelta1 atom of Asn46 at 2.25 A have been identified. The binding sites of Mn2+, Mg2+, and Ca2+ have not been found from different Fourier electron density maps. The Ni2+ and Co2+ ions bind to the Odelta atom of Asp52 at almost the same position, while the Yb3+ ion takes a different position from the Ni2+ and Co2+ ions. On the other hand, the anion Cl-, interacting with the Oeta atom of Tyr23 at a site of about 2.90 A, has also been determined for each crystal.     

Analysis of the requirements for pilus biogenesis at the outer membrane usher and the function of the usher C-terminus

Uropathogenic strains of Escherichia coli assemble type 1 and P pili to colonize the bladder and kidney respectively. These pili are prototype structures assembled by the chaperone/usher secretion pathway. In this pathway, a periplasmic chaperone works together with an outer membrane (OM) usher to control the folding of pilus subunits, their assembly into a pilus fibre and secretion of the fibre to the cell surface. The usher serves as the assembly and secretion platform in the OM. The usher has distinct functional domains, with the N-terminus providing the initial targeting site for chaperone-subunit complexes and the C-terminus required for subsequent stages of pilus biogenesis. In this study, we investigated the molecular interactions occurring at the usher during pilus biogenesis and the function of the usher C-terminus. We provide genetic and biochemical evidence that the usher functions as a complex in the OM and that interaction of the pilus adhesin with the usher is critical to prime the usher for pilus biogenesis. Analysis of C-terminal truncation and substitution mutants of the P pilus usher PapC demonstrated that the C-terminus is required for proper binding of chaperone-subunit complexes to the usher and plays an important role in assembly of complete pili.     

Molecular systematics of four endemic Batrachospermaceae (Rhodophyta) species in China with multilocus data

Four endemic Batrachospermaceae species in China, Batrachospermum hongdongense Xie & Feng, Batrachospermum longipedicellatum Hua & Shi, Kumanoa curvata (Shi) Vis et al., and Kumanoa intorta (Jao) Entwisle et al., were analyzed with multilocus data in order to assess their phylogenetic placement. Multilocus molecular data from one nuclear gene (the ribosomal SSU), one chloroplast gene (rbcL), and two mitochondrial genes (COI and the cox2-3 spacer) as well as morphological studies were used to determine the phylogenetic relationships of these endemic species within the Batrachospermales. Batrachospermum hongdongense and B. longipedicellatum had previously been placed in Batrachospermum section Batrachospermum, but based on the data from this study they should be transferred into section Helminthoidea. Kumanoa curvata and K. intorta clearly belong to the newly established genus Kumanoa.     

Biomechanical Characteristics of Osteoporotic Fracture Healing in Ovariectomized Rats: A Systematic Review

Biomechanical tests are widely used in animal studies on osteoporotic fracture healing. However, the biomechanical recovery process is still unknown, leading to difficulty in choosing time points for biomechanical tests and in correctly assessing osteoporotic fracture healing. To determine the biomechanical recovery process during osteoporotic fracture healing, studies on osteoporotic femur fracture healing with biomechanical tests in ovariectomized rat (OVX) models were collected from PUBMED, EMBASE, and Chinese databases. Quadratic curves of fracture healing time and maximum load were fitted with data from the analyzed studies. In the fitted curve for normal fractures, the predicted maximum load was 145.56 N, and the fracture healing time was 88.0 d. In the fitted curve for osteoporotic fractures, the predicted maximum load was 122.30 N, and the fracture healing time was 95.2 d. The maximum load of fractured femurs in OVX rats was also lower than that in sham rats at day 84 post-fracture (D84 PF). The fracture healing time was prolonged and maximum load at D84 PF decreased in OVX rats with closed fractures. The maximum load of Wister rats was higher than that of Sprague-Dawley (SD) rats, but the fracture healing time of SD and Wister rats was similar. Osteoporotic fracture healing was delayed in rats that were < = 12 weeks old when ovariectomized, and at D84 PF, the maximum load of rats < = 12 weeks old at ovariectomy was lower than that of rats >12 weeks old at ovariectomy. There was no significant difference in maximum load at D84 PF between rats with an osteoporosis modeling time <12 weeks and > = 12 weeks. In conclusion, fracture healing was delayed and biomechanical property decreased by osteoporosis. Time points around D95.2 PF should be considered for biomechanical tests of osteoporotic femur fracture healing in OVX rat models. Osteoporotic fracture healing in OVX rats was affected by the fracture type but not by the strain of the rat.     

A novel anti-CEACAM5 monoclonal antibody, CC4, suppresses colorectal tumor growth and enhances NK cells-mediated tumor immunity

Carcinoembryonic antigen (CEA, CEACAM5, and CD66e) has been found to be associated with various types of cancers, particularly colorectal carcinoma, and developed to be a molecular target for cancer diagnosis and therapy. In present study, we generated a novel anti-CEACAM5 monoclonal antibody, namely mAb CC4, by immunizing mice with living colorectal cancer LS174T cells. Immunohistochemical studies found that mAb CC4 specifically and strongly binds to tumor tissues, especially colorectal adenocarcinoma. In xenografted mice, mAb CC4 is specifically accumulated in tumor site and remarkably represses colorectal tumor growth. In vitro functional analysis showed that mAb CC4 significantly suppresses cell proliferation, migration and aggregation of colorectal cancer cells and also raises strong ADCC reaction. More interestingly, mAb CC4 is able to enhance NK cytotoxicity against MHC-I-deficient colorectal cancer cells by blocking intercellular interaction between epithelial CEACAM5 and NK inhibitory receptor CEACAM1. These data suggest that mAb CC4 has the potential to be developed as a novel tumor-targeting carrier and cancer therapeutic.     

新疆棉田土壤固氮菌遗传多样性分析

利用ERIC-PCR和16SrDNA全序列测定方法,研究了新疆棉田土壤中分离获得的58株固氮菌的遗传多样性及系统发育。采用平均连锁法(UPGMA)分析ERIC-PCR的聚类结果表明在Watson距离为0.65左右时可以将供试菌株分为9个大群。选取ERIC-PCR各群中代表菌株进行16SrRNA全序列测定分析,结果表明这些菌株分别属于Enterobacter、Bacillus、Acinetobacter、Pseudomonas、Serratia和Yersinia6个属。     

宫颈上皮内病变与HPV相关

目的了解辽宁省妇女生殖道人乳头瘤病毒（Human Papillomavirus,HPV）感染情况,研究辽宁省妇女宫颈上皮内病变与HPV感染的相关性。方法回顾性分析600例行核酸分子快速导流杂交基因芯片技术（Hybri Max）检测的患者,该600例患者均行薄层液基细胞学技术（Liguid-based cytologic teset,LCT）检查,有127例患者行病理活检,结合3种方法研究HPV感染与宫颈病变的相关性。结果导流杂交HPV-DNA检测结果与LCT结果相结合,600例患者中,感染HPV的阳性率分别为正常32%（92/288）,Asc-us42%（87/208）,LSIL53%（40/75）,HSIL86%（19/22）,癌100%（7/7）。导流杂交HPV-DNA检测结果与病理活检结果相结合,感染HPV的阳性率分别为：正常或慢性炎症36.17%（17/47）,CINⅠ66.67%（36/54）,CINⅡ-Ⅲ84.21%（16/19）,癌100%（7/7）,HPV感染阳性率随宫颈病变程度加重而明显升高。细胞学与组织学病理诊断符合率分别为LSIL72%（54/75）,HSIL86.36%（19/22）,SCC100%（7/7）。不同年龄阶段妇女感染HPV的阳性率依次为20-29岁46.76%（65/139）,30-39岁43.41%（79/182）,40-9岁40.48%（71/174）,50-59岁38.16%（29/76）,60-69岁37.50%（6/16）,70岁76.92%（10/13）。600例患者HPV感染总阳性率为40.83%（245/600）,在HPV21种亚型中,有19种亚型均被检测出,感染率最高的是HPV16 35.51%（87/245）,其它常见型别依次为HPV58,HPV6,HPV53,HPV18,HPV31,HPV52和cp8304。此外还发现高危型HPV16的感染率：正常或慢性炎症35.29%（6/17）CINⅠ33.33%（12/36）,CINⅡ-Ⅲ56.25%（9/16）,癌85.71%（6/7）,其感染率阳性率在各种程度的宫颈病变中占很大比重,也随宫颈病变的严重程度而增高,进一步论证了HPV16的高危性。结论辽宁省妇女HPV感染的主要亚型是HPV16,HPV58及HPV6.无论是与细胞学检测结果相结合还是与病理活检结果相结合,HPV感染阳性率均随宫颈病变程度的加重而增高。提示宫颈病变的防治重点应放在预防及治疗HPV感染。     

Ghrelin improves disturbed myocardial energy metabolism in rats with heart failure induced by isoproterenol

To explore the effects of ghrelin on disturbed myocardial energy metabolism during chronic heart failure (CHF). Rats were subcutaneously injected with isoproterenol (ISO) for 10 days with or without ghrelin for another 10 days. Enzyme immunoassay was to measure ghrelin concentrations. Compared with the control group, ISO‐treated rats showed suppressed cardiac function with high ghrelin/GHS‐R expressions. These rats also showed the decreases in food consumption and weight. The decreased levels of plasma glucose and myocardial glucogen, but the high lactate in blood and myocardium showed myocardial metabolic disturbance. Compared with the group given ISO alone, the rats with ghrelin (20 and 100 µg/kg/day) improved cardiac dysfunction and increased food intake by 13.5 and 14.2% (both P < 0.01), and rate of weight gain by 95% (P < 0.05) and 1.71‐fold (P < 0.01), respectively. The plasma glucose were increased by 49.7 and 50.8% (both P < 0.01), and myocardial glucogen, by 40.5 and 51.7% (both P < 0.01), but blood lactate decreased by 1.56‐ and 1.96‐fold (both P < 0.01), and myocardial lactate by 32.1 and 48.7% (both P < 0.05), respectively. Their MCT1 mRNA and protein expressions increased. The myocardial ghrelin/GHS‐R pathway can be upregulated during CHF. The ghrelin can attenuate cardiac dysfunction and energy metabolic disturbance in CHF rats. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.     

Lineage Specifiers： New Players in the Induction of Pluripotency

Pluripotency-associated factors and their rivals,lineage specifers,have long been considered the determining factors for the identity of pluripotent and differentiated cells,respectively.Therefore,factors that are employed for cellular reprogramming in order to induce pluripotency have been identifed mainly from embryonic stem cell(ESC)-enriched and pluripotency-associated factors.Recently,lineage specifers have been identifed to play important roles in orchestrating the process of restoring pluripotency.In this review,we summarize the latest discoveries regarding cell fate conversion using pluripotency-associated factors and lineage specifers.We highlight the value of the‘‘seesaw’’model in defning cellular identity,opening up a novel scenario to consider pluripotency and lineage specifcation.     

Xanthomonas type III effector XopD targets SUMO-conjugated proteins in planta

Xanthomonas campestris pathovar vesicatoria (Xcv) uses the type III secretion system (TTSS) to inject effector proteins into cells of Solanaceous plants during pathogenesis. A number of Xcv TTSS effectors have been identified; however, their function in planta remains elusive. Here, we provide direct evidence for a functional role for a phytopathogenic bacterial TTSS effector in planta by demonstrating that the Xcv effector XopD encodes an active cysteine protease with plant-specific SUMO substrate specificity. XopD is injected into plant cells by the TTSS during Xcv pathogenesis, translocated to subnuclear foci and hydrolyses SUMO-conjugated proteins in vivo. Our studies suggest that XopD mimics endogenous plant SUMO isopeptidases to interfere with the regulation of host proteins during Xcv infection.