Characterization of the novel temperate Escherichia coli phage phiStx2k.

A novel temperate phage, phiStx2k, was induced from a clinical Escherichia coli isolate producing Shiga toxin (Stx) 2k. The phage particles have an icosahedral head (50 nm in diameter) and a long non-contractile tail (149 nm long). The phage genome consists of 46,647 bp of double-stranded DNA with an average G + C content of 51%. Genome sequence comparisons suggested that phiStx2k represents a new genus in the class Caudoviricetes. phiStx2k was capable of converting non-Stx-producing E. coli strains to Stx producers. These results expand our knowledge on the characteristics of Stx phages and highlight the potential risks of the emergence of Stx-producing strains or novel pathogens via horizontal gene transfer.

Genetic Diversity and Expression of Intimin in Escherichia albertii Isolated from Humans, Animals, and Food.

Escherichia albertii (E. albertii) is an emerging diarrheagenic pathogen associated with sporadic infections and human gastroenteric outbreaks. The eae gene, which encodes intimin in the locus of enterocyte effacement (LEE) operon, contributes to the establishment of the attaching and effacing (A/E) lesion. Increasing collection of E. albertii strains from various sources has resulted in a rapid increase in the number of eae subtypes. This study systematically investigated the prevalence and genetic diversity of eae among E. albertii strains isolated from humans, animals, and food. The eae gene was present in 452/459 (98.5%) strains and 23 subtypes were identified including two novel subtypes, named eae-α11 and η3. The eae-σ subtype was the most predominant among humans, animals, and food-derived strains, while eae-γ3, τ, and α11 were unique in human-derived strains. Additionally, the LEE island was also analyzed at genomic, transcriptional, and functional levels through genomic analysis, quantitative reverse transcription PCR, and HEp-2 cell adherence assays, respectively. The eae transcript levels were variable and associated with eae subtypes. Three different adherence patterns, including localized adherence-like (LAL), diffuse adherence (DA), and detachment (DE), were observed among E. albertii strains. This study demonstrated a high diversity of functional intimin in E. albertii strains isolated from humans, animals, and food. Further in vivo and in vitro studies are warranted to better elucidate the role of intimin or LEE in different genetic backgrounds.

Characteristics of Shiga Toxin-Producing Escherichia coli Circulating in Asymptomatic Food Handlers.

Shiga toxin-producing Escherichia coli (STEC) is a foodborne zoonotic pathogen that causes diarrhea, hemorrhagic colitis (HC), and hemolytic uremic syndrome (HUS) worldwide. Since the infection can be asymptomatic, the circulation of STEC in some asymptomatic carriers, especially in healthy-food-related professionals, is not yet well understood. In this study, a total of 3987 anal swab samples from asymptomatic food handlers were collected, and ten swabs recovered STEC strains (0.251%). Of the ten STEC isolates, seven serotypes and eight sequence types (ST) were determined using whole genome sequencing (WGS). Two stx1 subtypes (stx1a and stx1c) and four stx2 subtypes (stx2a, stx2b, stx2d, and stx2e) were detected. Seven different insertion sites were found in fourteen Stx prophages, and the dmsB and yfhL were the newly identified insertion sites. The ten strains showed the variable Stx transcription levels after the mitomycin C induction. The whole-genome phylogeny indicated that the strains from the asymptomatic food handlers were genetically distant from the strains of HUS patients. The STEC isolates circulating in asymptomatic carriers might pose a low potential to cause disease.

The association of serum magnesium and chronic kidney disease: a two-sample mendelian randomization study of European descent.

BACKGROUND: Previous observational studies focused on the association of serum magnesium (SMg) and chronic kidney disease (CKD), but the conclusion was inconsistent. To investigate the causal relationship of SMg and CKD, we performed a two-sample mendelian randomization (TSMR) analysis using publicly datasets. METHOD: In mendelian randomization (MR) analysis, we used single nucleotide polymorphisms (SNPs) which had genetic statistical significance with SMg but not associated with kidney function and confounding factors as instrumental variable (IV). To select SNPs, we used publicly database of Genome Wide Association Study (GWAS) and Chronic Kidney Disease Genetics (CKDGen) Confirms. We used inverse-variance weighted (IVW), weighted median, MR-Egger regression, weighted mode, and simple mode approaches in TSMR analysis. RESULTS: We selected 4 SNPs (rs4072037, rs7965584, rs11144134 and rs448378) as IV. In IVW approach, the result of MR analysis for CKD was OR = 0.55, 95% CI: 0.06, 4.75, P = 0.58; for estimated glomerular filtration rate from creatinine (eGFR)crea was ß = -0.06, 95% CI: -1.08, 0.07, P = 0.39; for estimated glomerular filtration rate from cystatin C (eGFR)cys was ß = -0.03, 95% CI: -0.43, 0.36, P = 0.86, respectively per SD increase in SMg. When subgroup by diabetes mellitus (DM), the results for DM-eGFRcrea was ß = -0.33, 95% CI: -0.85, 0.19, P = 0.21; and for non-DM-eGFRcrea was ß = -0.03, 95% CI: -0.16, 0.11, P = 0.71. The results of other four MR approaches were consistent with IVW approach (all P > 0.05). CONCLUSION: Our TSMR analysis showed that SMg had no causal effect on kidney function and progress CKD in European descent. As for the results about overall population, the verified study is needed in future study.

Programmed Degradation of Pericarp Cells in Wheat Grains Depends on Autophagy.

Wheat is one of the most important food crops in the world, with development of the grains directly determining yield and quality. Understanding grain development and the underlying regulatory mechanisms is therefore essential in improving the yield and quality of wheat. In this study, the developmental characteristics of the pericarp was examined in developing wheat grains of the new variety Jimai 70. As a result, pericarp thickness was found to be thinnest in grains at the top of the spike, followed by those in the middle and thickest at the bottom. Moreover, this difference corresponded to the number of cell layers in the pericarp, which decreased as a result of programmed cell death (PCD). A number of autophagy-related genes (ATGs) are involved in the process of PCD in the pericarp, and in this study, an increase in ATG8-PE expression was observed followed by the appearance of autophagy structures. Meanwhile, following interference of the key autophagy gene ATG8, PCD was inhibited and the thickness of the pericarp increased, resulting in small premature grains. These findings suggest that autophagy and PCD coexist in the pericarp during early development of wheat grains, with both processes increasing from the bottom to the top of the spike. Moreover, PCD was also found to rely on ATG8-mediated autophagy. The results of this study therefore provide a theoretical basis for in-depth studies of the regulatory mechanisms of wheat grain development.

Relationships between menstrual status and obesity phenotypes in women: a cross-sectional study in northern China.

BACKGROUND: One of most important concerns of postmenopausal women is obesity. The relationships between menstruation status and obesity phenotypes are unclear. This study aimed to assess the associations between menstrual status and different obesity phenotypes in women. METHODS: In total, 5373 women aged ≥40 years were recruited from the Jidong and Kailuan communities. Basic information was collected via clinical examination, laboratory testing and standardized questionnaires. The women were stratified into the following three groups: menstrual period, menopausal transition period and postmenopausal period. General obesity was defined as a body mass index (BMI) of ≥28 kg/m2. Central obesity was defined as a waist-to-hip ratio (WHR) of > 0.85. Visceral obesity was defined as the presence of nonalcoholic fatty liver disease (NAFLD) and increased pericardial fat volume (PFV). RESULTS: The numbers of women in the menstrual, menopausal transition, and postmenopausal periods were 2807 (52.2%), 675 (12.6%) and 1891 (35.2%), respectively. The adjusted odds ratio (OR) and 95% confidence interval (CI) for central obesity among women in the menopausal transition and postmenopausal periods compared with women in the menstrual period were 0.99 (0.82-1.19) and 1.52 (1.26-1.84), respectively. The OR for NAFLD among postmenopausal women was 1.78 (1.44-2.20). The adjusted ß-coefficient (standard error, SE) for PFV among postmenopausal women was 41.25 (7.49). The adjusted OR for general obesity among postmenopausal women was 1.01 (0.77-1.34). CONCLUSIONS: This study demonstrated that menopause is an independent risk factor for central and visceral obesity but not general obesity.

Autophagic Survival Precedes Programmed Cell Death in Wheat Seedlings Exposed to Drought Stress.

Although studies have shown the concomitant occurrence of autophagic and programmed cell death (PCD) in plants, the relationship between autophagy and PCD and the factors determining this relationship remain unclear. In this study, seedlings of the wheat cultivar Jimai 22 were used to examine the occurrence of autophagy and PCD during polyethylene glycol (PEG)-8000-induced drought stress. Autophagy and PCD occurred sequentially, with autophagy at a relatively early stage and PCD at a much later stage. These findings suggest that the duration of drought stress determines the occurrence of PCD following autophagy. Furthermore, the addition of 3-methyladenine (3-MA, an autophagy inhibitor) and the knockdown of autophagy-related gene 6 (ATG6) accelerated PEG-8000-induced PCD, respectively, suggesting that inhibition of autophagy also results in PCD under drought stress. Overall, these findings confirm that wheat seedlings undergo autophagic survival under mild drought stress, with subsequent PCD only under severe drought.

Transcriptome characterization and differential expression analysis of cold-responsive genes in young spikes of common wheat.

With the frequent occurrence of climatic anomalies, spring frost has become a significant limiting factor on wheat production, especially during the reproductive growth stage. A high-throughput sequencing technology was applied and a total of 54 million clean reads that corresponded to 7.44 Gb of total nucleotides were generated. These reads were then de novo assembled into 120,715 unigenes with an average length of 627 bp. Functional annotations were then obtained by aligning all unigenes with public protein databases. In total, 9657 potential EST-SSRs were identified, and 6310 primer pairs for 1329 SSRs were obtained. Meanwhile, a comparison of four tag-based digital gene expression libraries, which was built from the control and cold-treated young spikes were performed. Overall, 526 up-regulated and 489 down-regulated genes were identified, and GO and KEGG pathway analyses of those genes were further conducted. Based on these results, a series of candidate genes involved in cold response pathways were identified, and 12 of them were confirmed by qRT-PCR. The combination of RNA-Seq and digital gene expression analysis in this study provides a powerful approach for investigating the transcriptional changes and obtained a large number of unigenes annotated to public databases.

Molecular mapping of a non-host resistance gene YrpstY1 in barley (Hordeum vulgare L.) for resistance to wheat stripe rust.

Cultivated barley (Hordeum vulgare L.) is considered as a non-host or inappropriate host species for wheat stripe rust caused by Puccinia striiformis f. sp. tritici. Most barley cultivars show a broad-spectrum resistance to wheat stripe rust. To determine the genes for resistance to wheat stripe rust in barley, a cross was made between a resistant barley line Y12 and a susceptible line Y16. The two parents, F(1) and 147 BC(1) plants were tested at seedling stage with Chinese prevalent race CYR32 of Puccinia striiformis f. sp. tritici by artificial inoculation in greenhouse. The results indicated that Y12 possessed one dominant resistance gene to wheat stripe rust, designated YrpstY1 provisionally. A total of 388 simple sequence repeat (SSR) markers were used to map the resistance gene in Y12 using bulked segregant analysis. A linkage map, including nine SSR loci on chromosome 7H and YrpstY1, was constructed using the BC(1) population, indicating that the resistance gene YrpstY1 is located on chromosome 7H. It is potential to transfer the resistance gene into common wheat for stripe rust resistance.