The gpsX gene encoding a glycosyltransferase is important for polysaccharide production and required for full virulence in Xanthomonas citri subsp. citri

<p>Abstract</p> <p>Background</p> <p>The Gram-negative bacterium <it>Xanthomonas citri </it>subsp. <it>citri </it>(<it>Xac</it>) causes citrus canker, one of the most destructive diseases of citrus worldwide. In our previous work, a transposon mutant of <it>Xac </it>strain 306 with an insertion in the <it>XAC3110 </it>locus was isolated in a screening that aimed at identifying genes related to biofilm formation. The <it>XAC3110 </it>locus was named as <it>bdp24 </it>for biofilm-defective phenotype and the mutant was observed to be affected in extracellular polysaccharide (EPS) and lipopolysaccharide (LPS) biosynthesis and cell motility. In this study, we further characterized the <it>bdp24 </it>(XAC3110) gene (designated as <it>gpsX</it>) using genetic complementation assays and expanded the knowledge about the function of the <it>gpsX </it>gene in <it>Xac </it>pathogenesis by investigating the roles of <it>gpsX </it>in EPS and LPS production, cell motility, biofilm formation on host leaves, stress tolerance, growth <it>in planta</it>, and host virulence of the citrus canker bacterium.</p> <p>Results</p> <p>The <it>gpsX </it>gene encodes a putative glycosyltransferase, which is highly conserved in the sequenced strains of <it>Xanthomonas</it>. Mutation of <it>gpsX </it>resulted in a significant reduction of the amount of EPS and loss of two LPS bands visualized on sodium dodecylsulphate- polyacrylamide gels. Biofilm assays revealed that the <it>gpsX </it>mutation affected biofilm formation by <it>Xac </it>on abiotic and biotic surfaces. The <it>gpsX </it>mutant showed delayed bacterial growth and caused reduced development of disease symptoms in susceptible citrus leaves. The <it>gpsX </it>mutant was more sensitive than the wild-type strain to various stresses, including the H₂O₂oxidative stress. The mutant also showed attenuated ability in cell motility but not in flagellar formation. Quantitative reverse transcription-PCR assays indicated that mutation of <it>gpsX </it>did not affect the expression of virulence genes such as <it>pthA </it>in <it>Xac </it>strain 306. The affected phenotypes of the <it>gpsX </it>mutant could be complemented to wild-type levels by the intact <it>gpsX </it>gene.</p> <p>Conclusions</p> <p>Taken together, our data confirm that the <it>gpsX </it>gene is involved in EPS and LPS synthesis and biofilm formation in <it>Xac </it>and suggest that the <it>gpsX </it>gene contributes to the adaptation of <it>Xac </it>to the host microenvironments at early stage of infection and thus is required for full virulence on host plants.</p

Genome-wide transcriptome analysis to evaluate the potential functions of liquid of fermented plant extract -Regulation of cholesterol metabolism in liver cells-

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Association between Helicobacter pylori infection and triglyceride levels: a nested cross-sectional study

BackgroundCurrently, the available evidence regarding the relationship between the lipid profile and Helicobacter pylori (H. pylori) infection is limited and conflicting. There is also a dearth of studies that have explored the possibility of sex-specific differences in the association between H. pylori infection and triglyceride levels.MethodsWe conducted a cross-sectional study involving 1,146 participants utilizing data from the National Health and Nutrition Examination Survey (NHANES) 1999-2000 conducted in the United States. A logistic regression model was employed to evaluate the association between H. pylori seropositivity and triglyceride levels. Subgroup analyses stratified by sex were conducted to explore sex-specific differences in this association.ResultsSerum triglyceride levels were significantly higher in H. pylori-seropositive participants than in H. pylori-seronegative participants. In the logistic regression analysis, there was a positive correlation between H. pylori seropositivity and triglyceride levels (OR=1.231; 95% CI, 1.016-1.491; P=0.033). In the subgroup analysis, the adjusted association between serum triglycerides and H. pylori seropositivity was significant in females (OR=1.732; 95% CI, 1.113-2.696; P=0.015) but not in males (OR=1.091; 95% CI, 0.698-1.705; P=0.704).ConclusionThe association between high triglyceride levels and H. pylori infection is specific to the female population

Transformational Leadership and Voice:When Does Felt Obligation to the Leader Matter?

Drawing on the notion that felt obligation is an important motivation variable that drives employees’ behavior, this study examines how leaders can evoke felt obligation in followers and to what extent such obligation can subsequently promote follower voice behavior. Using data from 384 Chinese employees and their 130 managers, we find that followers’ felt obligation to the leader (FOTL) serves as a mediator in the relationship between transformational leadership and employee voice behavior and that the mediation effect of FOTL is moderated by followers’ power distance orientation (PDO), such that the mediation effect is significant only for employees with low PDO. The theoretical and practical implications of these findings are discussed

Parametric Analysis of Flexible Logic Control Model

Based on deep analysis about the essential relation between two input variables of normal two-dimensional fuzzy controller, we used universal combinatorial operation model to describe the logic relationship and gave a flexible logic control method to realize the effective control for complex system. In practical control application, how to determine the general correlation coefficient of flexible logic control model is a problem for further studies. First, the conventional universal combinatorial operation model has been limited in the interval [0,1]. Consequently, this paper studies a kind of universal combinatorial operation model based on the interval [a,b]. And some important theorems are given and proved, which provide a foundation for the flexible logic control method. For dealing reasonably with the complex relations of every factor in complex system, a kind of universal combinatorial operation model with unequal weights is put forward. Then, this paper has carried out the parametric analysis of flexible logic control model. And some research results have been given, which have important directive to determine the values of the general correlation coefficients in practical control application

Molecular Cloning, Characterization, and mRNA Expression of Hemocyanin Subunit in Oriental River Prawn Macrobrachium nipponense

This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Hemocyanin is a copper-containing protein with immune function against disease. In this study, a hemocyanin subunit named MnHc-1 was cloned from Macrobrachium nipponense. The full-length cDNA of MnHc-1 was 2,163 bp with a 2,028-bp open reading frame (ORF) encoding a polypeptide of 675 amino acids. The MnHc-1 mRNA was expressed in the hepatopancreas, gill, hemocytes, intestine, ovary, and stomach, with the highest level in the hepatopancreas. In the infection trial, the MnHc-1 mRNA transcripts in the hemocytes were significantly downregulated at 3 h after injection of Aeromonas hydrophila and then upregulated at 6 h and 12 h, followed by a gradual recovery from 24 to 48 h. The MnHc-1 transcriptional expression in the hepatopancreas was measured after M. nipponense were fed seven diets with 2.8, 12.2, 20.9, 29.8, 43.1, 78.9, and 157.1 mg Cu kg−1 for 8 weeks, respectively. The level of MnHc-1 mRNA was significantly higher in the prawns fed 43.1–157.1 mg Cu kg−1 diet than in that fed 2.8–29.8 mg Cu kg−1 diet. This study indicated that the MnHc-1 expression can be affected by dietary copper and the hemocyanin may potentially participate in the antibacterial defense of M. nipponense