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When the airlift bioreactor is applied to the field of industrial fermentation, there is a common problem of low mixing and flow efficiency due to its simple structure. In order to expand the application of airlift bioreactor in the field of industrial fermentation, a new type of airlift bioreactor with three-dimensional bumps in the draft tube has been designed to enhance the mixing and flow of gas-liquid two-phase in the reactor. In order to determine the specific influence of the three-dimensional bumps on the internal flow field of the reactor, and to provide technical reference for the improvement of the structure of the airlift bioreactor, in this paper, the CFD simulation of this type of bioreactor is carried out. Based on the Euler multiphase flow, the Realizable k-ε model was used to analyze the flow field of the reactor with average gas-liquid flow linear velocity and temperature as parameters. The results show that under certain conditions, the three-dimensional bumps inside the draft tube can effectively accelerate the gas-liquid two-phase flow and better promotes the mixing of pig manure fermentation broth and air. [ABSTRACT FROM AUTHOR]

Collective wisdom is the ability of a group to perform more effectively than any individual alone. Through an evolutionary game-theoretic model of collective prediction, we investigate the role that reinforcement learning stimulus may play the role in enhancing collective voting accuracy. And collective voting bias can be dismissed through self-reinforcing global cooperative learning. Numeric simulations suggest that the provided method can increase collective voting accuracy. We conclude that real-world systems might seek reward-based incentive mechanism as an alternative to surmount group decision error. [ABSTRACT FROM AUTHOR]

Bacteriophage VP1 is a typing phage used for the phage subtyping of Vibrio cholerae O1 biotype El Tor, but the molecular mechanisms of its receptor recognition and the resistance of its host to infection are mostly unknown. In this study, we aimed to identify the host receptor and its role in resistance in natural VP1-resistant strains. Generating spontaneous resistance mutations and genome sequencing mutant strains found the polyQ protein VcpQ, which carries 46 glutamine residues in its Q-rich region, to be responsible for infection by VP1. VcpQ is a membrane protein and possibly forms homotrimers. VP1 adsorbed to V. cholerae through VcpQ. Sequence comparisons showed that 72% of natural VP1-resistant strains have fewer glutamines in the VcpQ Q-rich stretch than VP1-sensitive strains. This difference did not affect the membrane location and oligomer of VcpQ but abrogated VP1 adsorption. These mutant VcpQs did not recover VP1 infection sensitivity in a V. cholerae strain with vcpQ deleted. Our study revealed that the polyQ protein VcpQ is responsible for the binding of VP1 during its infection of V. cholerae and that glutamine residue reduction in VcpQ affects VP1 adsorption to likely be the main cause of VP1 resistance in natural resistant strains. The physiological functions of this polyQ protein in bacteria need further clarification; however, mutations in the polyQ stretch may endow V. cholerae with phage resistance and enhance survival against VP1 or related phages. [ABSTRACT FROM AUTHOR]

To explore transmission patterns and genetic relationships of Salmonella enterica serovar Paratyphi A in China, we conducted a genome-wide single-nucleotide polymorphism analysis on the strains in the 4 provinces in which incidence was highest during 1998-2012. Markedly phylogeographic clustering suggested regional virus circulation after introduction from areas in southeastern China. [ABSTRACT FROM AUTHOR]

Background: miRNAs are a class of non-coding RNA molecules that play crucial roles in the regulation of virushost interactions. The ever-increasing data of known viral miRNAs and human protein interaction network (PIN) has made it possible to study the targeting characteristics of viral miRNAs in the context of these networks. Results: We performed topological analysis to explore the targeting propensities of herpesvirus miRNAs from the view of human PIN and found that (1) herpesvirus miRNAs significantly target more hubs, moreover, compared with non-hubs (non-bottlenecks), hubs (bottlenecks) are targeted by much more virus miRNAs and virus types. (2) There are significant differences in the degree and betweenness centrality between common and specific targets, specifically we observed a significant positive correlation between virus types targeting these nodes and the proportion of hubs, and (3) K-core and ER analysis determined that common targets are closer to the global PIN center. Compared with random conditions, the giant connected component (GCC) and the density of the subnetwork formed by common targets have significantly higher values, indicating the module characteristic of these targets. Conclusions: Herpesvirus miRNAs preferentially target hubs and bottlenecks. There are significant differences between common and specific targets. Moreover, common targets are more intensely connected and occupy the central part of the network. These results will help unravel the complex mechanism of herpesvirus-host interactions and may provide insight into the development of novel anti-herpesvirus drugs. [ABSTRACT FROM AUTHOR]

Background Transmitted drug resistance (TDR) is an important public health issue, because TDRassociated mutation may affect the outcome of antiretroviral treatment potentially or directly. Men who have sex with men (MSM) constitute a major risk group for HIV transmission. However, current reports are scarce on HIV TDR-associated mutations and their co-variation among MSM. Methods Blood samples from 262 newly diagnosed HIV-positive, antiretroviral therapy (ART)-naïve MSM, were collected from January 2011 and December 2013 in Beijing. The polymerase viral genes were sequenced to explore TDR-associated mutations and mutation co-variation. Results A total of 223 samples were sequenced and analyzed. Among them, HIV-1 CRF01_AE are accounted for 60.5%, followed by CRF07_BC (27.8%), subtype B (9.9%), and others. Fiftyseven samples had at least one TDR-associated mutation, mainly including L10I/V (6.3%), A71L/T/V (6.3%), V179D/E (5.4%), and V106I (2.7%), with different distributions of TDRassociated mutations by different HIV-1 subtypes and by each year. Moreover, eight significant co-variation pairs were found between TDR-associated mutations (V179D/E) and seven overlapping polymorphisms in subtype CRF01_AE. Conclusions To date, this work consists the most comprehensive genetic characterization of HIV-1 TDRassociated mutations prevalent among MSM. It provides important information for understanding TDR and viral evolution among Chinese MSM, a population currently at particularly high risk of HIV transmission. [ABSTRACT FROM AUTHOR]

Activation of telomerase is linked to tumorigenesis and has been observed in a variety of human tumors. Previous reports demonstrated that p53 represses human telomerase reverse transcriptase (hTERT), a key component for telomerase activity. The p73 protein displays a tumor suppressor activity similar to p53. In the present study, we examined the effect of transactivation competent p73 isoforms on hTERT expression in p53-negative human H1299 cells. Overexpression of C-terminal p73 isoforms (α, β, γ, δ) resulted in a clear down-regulation of hTERT promoter activity. The strongest inhibitory effect, comparable with p53, was observed for p73β. Moreover, suppression of hTERT expression was also mediated by endogenous p73 after activation of E2F1 in H1299ER-E2F1 cells. Mutations in the Sp1 transcription factor-binding sites of the proximal core promoter region significantly abolished p73-induced repression, suggesting that the effect is mediated by Sp1. Finally, we demonstrate that p73 directly interacts with Sp1, suggesting that formation of a p73-Sp1 complex is the underlying mechanism for p73-triggered inhibition of hTERT expression. Our findings provide additional evidence that p73 mimics p53 in many aspects in cells lacking functional p53, thereby contributing to tumor surveillance. [ABSTRACT FROM AUTHOR]

A case of Rickettsia sibirica subspecies sibirica BJ-90 infection in China was identified by metagenomic analysis of an eschar biopsy specimen and confirmed by nested PCR. Seroprevalence of spotted fever group Rickettsia was ≈17.4% among the local population. This report highlights the threat of rickettsioses to public health in the Qinghai-Tibet Plateau. [ABSTRACT FROM AUTHOR]

The genus Shewanella comprises a group of marine-dwelling species with worldwide distribution. Several species are regarded as causative agents of food spoilage and opportunistic pathogens of human diseases. In this study, a standard multilocus sequence analysis (MLSA) based on six protein-coding genes (gyrA, gyrB, infB, recN, rpoA and topA) was established as a rapid and accurate identification tool in fifty-nine type Shewanella strains. This method yielded sufficient resolving power in regard to enough informative sites, adequate sequence divergences and distinct interspecies branches. The stability of phylogenetic topology was supported by high bootstrap values and concordance with different methods. The reliability of the MLSA scheme was further validated by identical phylogenies and high correlations of genomes. The MLSA approach provided a robust system to exhibit evolutionary relationships in the Shewanella genus. The split network tree proposed twelve distinct monophyletic clades with identical G+C contents and high genetic similarities. Eighty-six tested strains were investigated to explore the population biology of the Shewanella genus in China. The most prevalent Shewanella species were Shewanella algae, Shewanella xiamenensis, Shewanella chilikensis, Shewanella indica, Shewanella seohaensis and Shewanella carassii. The strains frequently isolated from clinical and food samples highlighted the importance of increasing the surveillance of Shewanella species. Combined with the genetic, genomic and phenotypic analyses, Shewanella upenei should be considered a synonym of S. algae, and Shewanella pacifica should be reclassified as a synonym of Shewanella japonica. IMPORTANCE The MLSA scheme based on six housekeeping genes (HKGs) (gyrA, gyrB, infB, recN, rpoA and topA) is well established as a reliable tool for taxonomic, evolutionary and population diversity analyses of the genus Shewanella in this study. The standard MLSA method allows researchers to make rapid, economical and precise identification of Shewanella strains. The robust phylogenetic network of MLSA provides profound insight into the evolutionary structure of the genus Shewanella. The population genetics of Shewanella species determined by the MLSA approach plays a pivotal role in clinical diagnosis and routine monitoring. Further studies on remaining species and genomic analysis will enhance a more comprehensive understanding of the microbial systematics, phylogenetic relationships and ecological status of the genus Shewanella. [ABSTRACT FROM AUTHOR]

Although plant non-specific lipid transfer proteins (ns-LTPs) are characterized by their ability to bind and transfer a broad range of hydrophobic ligands in vitro, their biological functions in vivo remain unclear. Recently, it has been proposed that ns-LTPs may play a key role in plant defense mechanisms, particularly during the induction of systemic acquired resistance, however, very little is known about the regulation in this process. We report that the binding of maize non-specific lipid transfer protein ( Zm-LTP) to calmodulin (CaM) is in a calcium-independent manner. To better understand the interaction mechanism between Zm-LTP and CaM, the CaM-binding site of Zm-LTP was mapped to the region of amino acids 46–60. Point mutations indicate that four amino acid residues, R46, R47, K54 and R58, in this region are crucial for binding. Furthermore, we tested the effects of CaM on the lipid-binding activity of Zm-LTP in the presence of Ca2+, EGTA, N-(6-aminohexyl)-5-chloro-1-naphthalene sulfonamide and trifluoperazine respectively. We also investigated the structural features of CaM-binding motifs in LTPs from different species and strong differences were observed. Taken together, our results suggest that the interaction with CaM could be a common feature of plant LTPs. The identification and characterization of CaM-binding domain of LTPs should provide new insights into the mechanism by which the physiological functions of LTPs are regulated. [ABSTRACT FROM AUTHOR]