Multilocus sequence typing and virulence factors analysis of Escherichia coli O157 strains in China

Escherichia coli O157:H7, an important food-borne pathogen, has become a major public health concern worldwide. The aim of this study was to investigate the molecular epidemiologic feature of E. coli O157:H7 strains in China. 105 E. coli O157:H7 isolates were collected from various hosts and places over 9 years. A multilocus sequence typing scheme (MLST) was applied for bacteria genotyping and polymerase chain reaction (PCR) was used for virulence factor identification. Seven new MLST sequence types (STs), namely ST836, ST837, ST838, ST839, ST840, ST841, and ST842 were identified, which grouped into two lineages. Phylogenetic analysis suggested that the most two frequent STs in China, ST837 and ST836, may be the derivatives of E. coli O157:H7 Sakai or E. coli O157:H7 EDL933. Geographical diversity and host variety of E. coli O157:H7 were observed in China. In addition, the different distribution of tccp was detected. The data presented herein provide new insights into the molecular epidemiologic feature of E. coli O157:H7, and aid in the investigation of the transmission regularity and evolutionary mechanism of E. coli O157:H7.     

Involvement of c‐Jun N‐terminal kinase and extracellular signal‐regulated kinase 1/2 in EGF‐induced angiogenesis

Angiogenesis is a process during which endothelial cells divide and migrate to form new capillaries from the preexisting blood vessels. The present study was designed to investigate whether MAPKs (mitogen‐activated protein kinases) play crucial roles in regulating EGF (epidermal growth factor)‐induced endothelial cell angiogenesis. Our results showed that EGF stimulated HUVEC (human umbilical vein endothelial cells) proliferation in a concentration‐dependent manner, of which the maximum effective concentration of EGF was 10 ng/ml. Western blot analysis showed that EGF at 10 ng/ml significantly induced the phosphorylation of ERK1/2 (extracellular signal‐regulated kinase 1 and 2) and p38 kinase at 5 min, while it induced the phosphorylation of JNK/SAPK (c‐Jun N‐terminal kinase/stress‐activated protein kinase) at 15 min. Further results showed that a JNK/SAPK inhibitor, SP600125, and a specific siRNA JNK/SAPK could both significantly inhibit EGF‐induced tube formation in HUVEC cells, and an ERK1/2 inhibitor PD098059 could also block the tube formation in some content, while a p38 inhibitor SB203580 failed to do so. Furthermore, only SP600125 significantly inhibited EGF‐induced HUVEC cell proliferation under no cytotoxic concentration, so did JNK/SAPK siRNA. In conclusion, JNK/SAPK and ERK1/2 signals therefore play critical roles in EGF‐mediated HUVEC cell angiogenesis.     

Mosquito (Diptera: Culicidae) fauna in an area endemic for West Nile virus

Mosquito collections with CDC light traps using dry ice and pigeon‐baited traps were carried out in south Moravia (Czech Republic) from April to October in 2007 and 2008 at two study sites. In 2007, 11 two‐day captures were carried out in two‐week intervals, and 1,490 female mosquitoes of nine species were caught. In 2008, 15 two‐day trappings of mosquitoes were carried out: 6,778 females of 22 species of mosquitoes were trapped. The results showed marked differences in abundance and species composition of mosquitoes between both study sites and between the trapping methods. In the floodplain forest ecosystem of the Soutok study area, Aedes vexans predominated. The species composition in the Nesyt study site was more varied and the most common species was Culex pipiens. At the latter study site, Anopheles hyrcanus (var. pseudopictus) and Uranotaenia unguiculata, mosquito species with largely southern Eurasian distribution, were repeatedly demonstrated. The largest capture of mosquitoes was in traps with CO₂ placed at a height 1 m above the ground. The capture of mosquitoes in the pigeon‐baited traps as well as in the traps with CO₂ placed in the canopy of trees was markedly lower in both study sites, with the predominant species being Culex pipiens.     

JH biosynthesis by reproductive tissues and corpora allata in adult longhorned beetles, Apriona germari

We report on juvenile hormone (JH) biosynthesis from long‐chain intermediates by specific reproductive tissues and the corpora allata (CA) prepared from adult longhorned beetles, Apriona germari. The testes, male accessory glands (MAGs), ovaries, and CA contained the long‐chain intermediates in the JH biosynthetic pathway, farnesoic acid (FA), methyl farnesoate (MF), and JH III. The testes and ovaries, but not CA, produced radioactive JH III after the addition of ³H‐methionine and, separately, unlabeled methionine, to the incubation medium. We inferred that endogenous FA is methylated to MF in the testes and ovaries. Addition of farnesol led to increased amounts of FA in the testes, MAGs, ovaries, and CA, indicating oxidation of farnesol to FA. Addition of FA to incubation medium yielded increased JH III, again indicating methylation of FA to MF in the testes, MAGs, ovaries, but not CA. Addition of MF to incubation medium also led to JH III, from which we inferred the epoxidation of MF to JH III. JH biosynthesis from farnesol in the testes, MAGs, and ovaries of A. germari proceeds via oxidation to FA, methylation to MF, and epoxidation to JH III. This is a well‐known pathway to JH III, described here for the first time in reproductive tissues of longhorned beetles. © 2010 Wiley Periodicals, Inc.     

Influence of the acetylcholinesterase active site protonation on omega loop and active site dynamics

Existence of alternative entrances in acetylcholinesterase (AChE) could explain the contrast between the very high AChE catalytic efficiency and the narrow and long access path to the active site revealed by X-ray crystallography. Alternative entrances could facilitate diffusion of the reaction products or at least water and ions from the active site. Previous molecular dynamics simulations identified side door and back door as the most probable alternative entrances. The simulations of non-inhibited AChE suggested that the back door opening events occur only rarely (0.8% of the time in the 10ns trajectory). Here we present a molecular dynamics simulation of non-inhibited AChE, where the back door opening appears much more often (14% of the time in the 12ns trajectory) and where the side door opening was observed quite frequently (78% of trajectory time). We also present molecular dynamics, where the back door does not open at all, or where large conformational changes of the AChE omega loop occur together with alternative passage opening events. All these differences in AChE dynamical behavior are caused by different protonation states of two glutamate residues located on bottom of the active site gorge (Glu202 and G450 in Mus musculus AChE). Our results confirm the results of previous molecular dynamics simulations, expand the view and suggest the probable reasons for the overall conformational behavior of AChE omega loop.     

Condition status and parasite infection of Neogobius kessleri and N. melanostomus (Gobiidae) in their native and non-native area of distribution of the Danube River

The success of introduced species is often facilitated by escape from the effects of natural predators and parasites. Introduced species can profit from this favourable situation, attaining higher population densities and greater individual sizes in novel areas. In this study, somatic condition and parasite infection were compared between native and non-native populations of Neogobius kessleri Günther; introduced only within the interconnected Danube and Rhine River system, and N. melanostomus (Pallas); widely introduced throughout several river systems in Europe and North America. Higher values of Fulton’s condition factor were observed in non-native populations of both goby species. Neogobius melanostomus attained higher gonadosomatic index values in non-native populations, indicating potential increased investment in reproduction in its new area. A lower splenosomatic index was observed in non-native populations, especially in N. melanostomus. Parasite infracommunity richness and mean abundance were higher in N. kessleri in both native and non-native populations, suggesting higher susceptibility of N. kessleri to these parasites. Non-native populations of both hosts showed higher infra-community richness as a result of acquiring parasites native to the new area, but lower parasite abundance. Differences in success of the introduction and establishment in new areas between the two fish species may be associated with a relatively low parasite infection rate and a higher gonadosomatic index in non-native populations of N. melanostomus in comparison to N. kessleri.     

S3EPY: a Sparky extension for determination of small scalar couplings from spin-state-selective excitation NMR experiments

S3EPY is a Python extension to the program Sparky written to facilitate the assessment of coupling constants from in-phase/antiphase and spin-state-selective excitation (S³E) experiments. It enables the routine use of small scalar couplings by automating the coupling evaluation procedure. S3EPY provides an integrated graphical user interface to programs which outputs graphs and the table of determined couplings.