Arsenic methylation by a novel ArsM As(III) S-adenosylmethionine methyltransferase that requires only two conserved cysteine residues

Arsenic (As) biomethylation is an important component of the As biogeochemical cycle that can influence As toxicity and mobility in the environment. Biomethylation of As is catalyzed by the enzyme arsenite (As[III]) S-adenosylmethionine methyltransferase (ArsM). To date, all identified ArsM orthologs with As(III) methylation activities have four conserved cysteine residues, which are thought to be essential for As(III) methylation. Here, we isolated an As(III)-methylating bacterium, Bacillus sp. CX-1, and identified a gene encoding a S-adenosylmethionine methyltranserase termed BlArsM with low sequence similarities (≤ 39%) to other ArsMs. BlArsM has six cysteine residues (Cys10, Cys11, Cys145, Cys193, Cys195 and Cys268), three of which (Cys10, Cys145 and Cys195) align with conserved cysteine residues found in most ArsMs. BlarsM is constitutively expressed in Bacillus sp. CX-1. Heterologous expression of BlarsM conferred As(III) resistance. Purified BlArsM methylated both As(III) and methylarsenite (MAs[III]), with a final product of dimethylarsenate (DMAs[V]). When all six cysteines were individually altered to serine residues, only C145S and C195S derivatives lost the ability to methylate As(III) and MAs(III). The derivative C10S/C11S/C193S/C268S was still active. These results suggest that BlArsM is a novel As(III) S-adenosylmethionine methyltransferase requiring only two conserved cysteine residues. A model of As(III) methylation by BlArsM is proposed.

Microbial Processes Mediating the Evolution of Methylarsine Gases from Dimethylarsenate in Paddy Soils

Arsenic (As) biovolatilization is an important component of the global As biogeochemical cycle. Soils can emit various methylarsine gases, but the underlying microbial processes remain unclear. Here, we show that the addition of molybdate (Mo), an inhibitor of sulfate-reducing bacteria, greatly enhanced dimethylarsine evolution from dimethylarsenate [DMAs(V)] added to two paddy soils. Molybdate addition significantly affected the microbial community structure. The aerobic enrichment cultures from both soils volatilized substantial amounts of dimethylarsine from DMAs(V) in the presence of Mo, whereas the anaerobic enrichment cultures did not. A Bacillus strain (CZ-2) capable of reducing DMAs(V) to dimethylarsine was isolated from the aerobic enrichment culture, and its volatilization ability was enhanced by Mo. RNA-seq analysis identified 10 reductase genes upregulated by Mo. Addition of the reducing agent NADH increased dimethylarsine volatilization by strain CZ-2, suggesting that DMAs(V) reductase is an NADH-dependent enzyme. The strain could not methylate arsenite or convert monomethylarsenate and DMAs(V) to trimethylarsine. Our results show that dimethylarsine evolution from DMAs(V) is independent of the As methylation pathway and that Mo enhances dimethylarsine evolution from paddy soils by shifting the microbial community structure and enhancing the reduction of DMAs(V) to dimethylarsine, possibly through upregulating the expression of DMAs(V) reductase gene(s).

Presence of Chlamydia trachomatis and Mycoplasma spp., but not Neisseria gonorrhoeae and Treponema pallidum, in women undergoing an infertility evaluation: high prevalence of tetracycline resistance gene tet(M)

Chlamydia trachomatis, Mycoplasma spp., Neisseria gonorrhoeae and Treponema pallidum are sexually transmitted pathogens that threaten reproductive health worldwide. In this study, vaginal swabs obtained from women (n = 133) that attended an infertility clinic in China were tested with qPCRs for C. trachomatis, Mycoplasma spp., N. gonorrhoeae, T. pallidum and tetracycline resistance genes. While none of vaginal swabs were positive for N. gonorrhoeae and T. pallidum, 18.8% (25/133) of the swabs were positive for Chlamydia spp. and 17.3% of the swabs (23/133) were positive for Mycoplasma species. All swabs tested were positive for tetracycline resistance gene tet(M) which is the most effective antibiotic for bacterial sexually transmitted infections. The qPCRs determined that the gene copy number per swab for tet(M) was 7.6 times as high as that of C. trachomatis 23S rRNA, and 14.7 times of Mycoplasma spp. 16S rRNA. In China, most hospitals do not detect C. trachomatis and Mycoplasma spp. in women with sexually transmitted infections and fertility problems. This study strongly suggests that C. trachomatis and Mycoplasma spp. should be routinely tested in women with sexually transmitted infections and infertility in China, and that antimicrobial resistance of these organisms should be monitored. Further studies are warranted to determine the prevalences in different regions and associated risk factors.

Survey of vector-borne agents in feral cats and first report of Babesia gibsoni in cats on St Kitts, West Indies

Background

As there is little data on vector-borne diseases of cats in the Caribbean region and even around the world, we tested feral cats from St Kitts by PCR to detect infections with Babesia, Ehrlichia and spotted fever group Rickettsia (SFGR) and surveyed them for antibodies to Rickettsia rickettsii and Ehrlichia canis.

Results

Whole blood was collected from apparently healthy feral cats during spay/ neuter campaigns on St Kitts in 2011 (N = 68) and 2014 (N = 52). Sera from the 52 cats from 2014 were used to detect antibodies to Ehrlichia canis and Rickettsia rickettsii using indirect fluorescent antibody tests and DNA extracted from whole blood of a total of 119 cats (68 from 2011, and 51 from 2014) was used for PCRs for Babesia, Ehrlichia and Rickettsia. We could not amplify DNA of SFG Rickettsia in any of the samples but found DNA of E. canis in 5% (6/119), Babesia vogeli in 13% (15/119), Babesia gibsoni in 4% (5/119), mixed infections with B. gibsoni and B. vogeli in 3% (3/119), and a poorly characterized Babesia sp. in 1% (1/119). Overall, 10% of the 52 cats we tested by IFA for E. canis were positive while 42% we tested by indirect fluorescent antibody (IFA) for R. rickettsii antigens were positive.

Conclusions

Our study provides the first evidence that cats can be infected with B. gibsoni and also indicates that cats in the Caribbean may be commonly exposed to other vector-borne agents including SFGR, E. canis and B. vogeli. Animal health workers should be alerted to the possibility of clinical infections in their patients while public health workers should be alerted to the possibility that zoonotic SFGR are likely circulating in the region.

Microarray analysis of an synthetic α-synuclein induced cellular model reveals the expression profile of long non-coding RNA in Parkinson's disease

Long non-coding RNAs (lncRNAs) are a new research focus that are reported to influence the pathogenetic process of neurodegenerative disorders. To uncover new disease-associated genes and their relevant mechanisms, we carried out a gene microarray analysis based on a Parkinson's disease (PD) in vitro model induced by α-synuclein oligomers. This cellular model induced by 25 μmol/L α-synuclein oligomers has been confirmed to show the stable, transmissible neurotoxicity of α-synuclein, a typical PD pathological marker. And several differentially expressed lncRNAs and mRNAs were identified in this model, such as G046036, G030771, AC009365.4, RPS14P3, CTB-11I22.1, and G007549. Subsequent ceRNA analysis determined the potential relationships between these lncRNAs and their associated mRNAs and microRNAs. The results of the present study widen our horizon of PD susceptibility genes and provide new pathways towards efficient diagnostic biomarkers and therapeutic targets for PD.

X-linked Hyper-IgM Syndrome: A Phenotype of Crohn's Disease with Hemophagocytic Lymphohistiocytosis

X-linked hyper-immunoglobulin M (IgM) syndrome is characterized by recurrent infections, low or undetectable levels of IgG and IgA, and normal to increased serum IgM, and is also rare. It is associated with mutation in the gene encoding CD40 ligand. This study aimed to describe the first international report of hemizygous CD40LG c.542G>A mutation in a 5-year-old boy with a phenotype of Crohn's disease and hemophagocytic lymphohistiocytosis. Also, the clinical implications of this mutation and associated atypical phenotype are discussed.

[Expression of PAK1 in bladder cancer and its influence on invasion of bladder cancer cells]

Objective: To investigate the expression of p21-activated kinase 1 (PAK1) in bladder cancer and its biological influence on invasion ability of bladder cancer cells. Methods: A total of 54 paraffin-embedded bladder cancer tissue samples and 12 normal bladder tissue specimens were retrieved in Jinshan Hospital Affiliated to Fudan University between January 2009 and December 2012. The expression of PAK1 in these tissues was detected by immunohistochemical staining. The PAK1 mRNA and protein levels were measured in bladder cancer cell lines and human normal bladder epithelial cell line using real-time, fluorescence-based quantitative polymerase chain reaction (RT-PCR) and Western blot, respectively. A stable PAK1 gene silencing bladder cancer cell strain 5637 were successfully constructed. After treatment with PAK1 RNA interference(RNAi), the ability of migration and invasion of the 5637 cell was evaluated using a Transwell system. Results: The expression of PAK1 proteins was significantly higher in bladder cancer tissues than in normal bladder tissues (28/54 vs 1/12, P<0.05). The overexpression of PAK1 was positively correlated with high histological grade, lymph node metastasis, and tumor size (all P<0.05). The mRNA level and protein level of PAK1 was much higher in bladder cancer cell lines T24, 5637 than human normal urothelial cell line SV-HUC-1.PCR and Western blot showed satisfactory inhibitory effect of PAK1 short hairpin RNA (shRNA) on PAK1 expression in 5637 bladder cancer cells. The number of PAK1 RNAi-treated 5637 cells traversed the membrane was decreased compared with the control group in migration and invasion assays. Conclusions: Overexpression of PAK1 in bladder cancer tissues may be an important feature of bladder cancer and related with the metastasis and invasion of bladder cancer. The molecular mechanisms involved in regulation of PAK1 expression needs further research.

PRC2 specifies ectoderm lineages and maintains pluripotency in primed but not naïve ESCs

Polycomb repressive complex 2 and the epigenetic mark that it deposits, H3K27me3, are evolutionarily conserved and play critical roles in development and cancer. However, their roles in cell fate decisions in early embryonic development remain poorly understood. Here we report that knockout of polycomb repressive complex 2 genes in human embryonic stem cells causes pluripotency loss and spontaneous differentiation toward a meso-endoderm fate, owing to de-repression of BMP signalling. Moreover, human embryonic stem cells with deletion of EZH1 or EZH2 fail to differentiate into ectoderm lineages. We further show that polycomb repressive complex 2-deficient mouse embryonic stem cells also release Bmp4 but retain their pluripotency. However, when converted into a primed state, they undergo spontaneous differentiation similar to that of hESCs. In contrast, polycomb repressive complex 2 is dispensable for pluripotency when human embryonic stem cells are converted into the naive state. Our studies reveal both lineage- and pluripotent state-specific roles of polycomb repressive complex 2 in cell fate decisions.

Polycomb repressive complex 2 (PRC2) plays an essential role in development by modifying chromatin but what this means at a cellular level is unclear. Here, the authors show that ablation of PRC2 genes in human embryonic stem cells and in mice results in changes in pluripotency and the primed state of cells.

Fe2Ni2N nanosheet array: an efficient non-noble-metal electrocatalyst for non-enzymatic glucose sensing

It is very important to develop enhanced electrochemical sensing platforms for molecular detection and non-noble-metal nanoarray architecture, as electrochemical catalyst electrodes have attracted great attention due to their large specific surface area and easy accessibility to target molecules. In this paper, we demonstrate that an Fe₂Ni₂N nanosheet array grown on Ti mesh (Fe₂Ni₂N NS/TM) shows high electrocatalytic activity toward glucose electrooxidation in alkaline medium. As an electrochemical glucose sensor, such an Fe₂Ni₂N NS/TM catalyst electrode demonstrates superior sensing performance with a short response time of less than 5 s, a wide linear range of 0.05 μM-1.5 mM, a low detection limit of 0.038 μM (S/N = 3), a high sensitivity of 6250 μA mM^-1 cm^-2, as well as high selectivity and long-term stability.

WIDE AND THICK GRAIN 1, which encodes an otubain-like protease with deubiquitination activity, influences grain size and shape in rice

Grain size and shape are two crucial traits that influence grain yield and grain appearance in rice. Although several factors that affect grain size have been described in rice, the molecular mechanisms underlying the determination of grain size and shape are still elusive. In this study we report that WIDE AND THICK GRAIN 1 (WTG1) functions as an important factor determining grain size and shape in rice. The wtg1-1 mutant exhibits wide, thick, short and heavy grains and also shows an increased number of grains per panicle. WTG1 determines grain size and shape mainly by influencing cell expansion. WTG1 encodes an otubain-like protease, which shares similarity with human OTUB1. Biochemical analyses indicate that WTG1 is a functional deubiquitinating enzyme, and the mutant protein (wtg1-1) loses this deubiquitinating activity. WTG1 is expressed in developing grains and panicles, and the GFP-WTG1 fusion protein is present in the nucleus and cytoplasm. Overexpression of WTG1 results in narrow, thin, long grains due to narrow and long cells, further supporting the role of WTG1 in determining grain size and shape. Thus, our findings identify the otubain-like protease WTG1 to be an important factor that determines grain size and shape, suggesting that WTG1 has the potential to improve grain size and shape in rice.

Arsenicibacter rosenii gen. nov., sp. nov., an efficient arsenic methylating and volatilizing bacterium isolated from an arsenic-contaminated paddy soil

A novel bacterium with strong arsenic (As) methylation and volatilization abilities, designated strain SM-1T, was isolated from an As-contaminated paddy soil. SM-1T is strictly aerobic, rod-shaped, non-motile, Gram-negative and orange-coloured. Phylogenetic analysis revealed that strain SM-1T showed low 16S rRNA gene sequence similarities (≤88 %) to members of established genera in the family Cytophagaceae. Growth of this strain was observed at 15-45 °C (optimum, 37 °C), pH 6.0-8.0 (optimum, 7.0) and 0-0.5 % (w/v) NaCl. The major cellular fatty acids were C16 : 1ω5c and iso-C15 : 0. The respiratory quinone was MK-7, and the predominant polar lipids were phosphatidylethanolamine, an unidentified lipid (L), and an unidentified aminolipid (AL2). The DNA G+C content was 51.5 mol%. On the basis of phenotypic, phylogenetic and chemotaxonomic properties, strain SM-1T represents a novel species in a new genus within the family Cytophagaceae, for which the name Arsenicibacter rosenii gen. nov., sp. nov. is proposed. The type strain of Arsenicibacter rosenii is SM-1T (=CCTCC AB 2017086T=KCTC 52624T).

MicroRNA expression, target genes, and signaling pathways in infants with a ventricular septal defect

This study aimed to systematically investigate the relationship between miRNA expression and the occurrence of ventricular septal defect (VSD), and characterize the miRNA target genes and pathways that can lead to VSD. The miRNAs that were differentially expressed in blood samples from VSD and normal infants were screened and validated by implementing miRNA microarrays and qRT-PCR. The target genes regulated by differentially expressed miRNAs were predicted using three target gene databases. The functions and signaling pathways of the target genes were enriched using the GO database and KEGG database, respectively. The transcription and protein expression of specific target genes in critical pathways were compared in the VSD and normal control groups using qRT-PCR and western blotting, respectively. Compared with the normal control group, the VSD group had 22 differentially expressed miRNAs; 19 were downregulated and three were upregulated. The 10,677 predicted target genes participated in many biological functions related to cardiac development and morphogenesis. Four target genes (mGLUR, Gq, PLC, and PKC) were involved in the PKC pathway and four (ECM, FAK, PI3 K, and PDK1) were involved in the PI3 K-Akt pathway. The transcription and protein expression of these eight target genes were significantly upregulated in the VSD group. The 22 miRNAs that were dysregulated in the VSD group were mainly downregulated, which may result in the dysregulation of several key genes and biological functions related to cardiac development. These effects could also be exerted via the upregulation of eight specific target genes, the subsequent over-activation of the PKC and PI3 K-Akt pathways, and the eventual abnormal cardiac development and VSD.

Two new KIT exon 13 mutations in one gastric gastrointestinal stromal tumor (GIST)

Gastrointestinal stromal tumors (GISTs) are the most frequently mesenchymal tumors found in the gastrointestinal tract. These tumors are usually composed of spindle-shaped cells. More than 80% of GISTs harbor mutations of KIT gene which encodes for an important receptor tyrosine kinase (RTK) type III. Within KIT gene mutations, the mutation of exon 13 is very rare. Here we described a case of GIST in a 42-year-old male which carried two new KIT exon 13 mutations (R634W and N655T). This patient was diagnosed with upper digestive tract hemorrhage and later CT scan revealed a 2.2 cm × 4.0 cm soft-tissue mass on the posterior wall of the stomach. The patient went through a laparoscopic gastrectomy. Following pathological examination revealed this tumor to be a low-risk GIST. Gene sequencing analysis shown that the tumor had two mutations in KIT exon 13, which were not found in the literature. The postoperative course was uneventful and no recurrence was observed after 6 months. Furthermore, we also gave a short review of previously published papers describing KIT exon 13 mutations.

[Trend of caesarean section rate and puerpera characteristics: based on Robson classification]

Objective: To analyze the trend in caesarean section rate and puerpera characteristics in hospital, and provide valuable information for maternal and child health policy making and clinical practice. Methods: A total of 12 041 women who delivered in the affiliated Chaohu Hospital of Anhui Medical University from October 1, 2010 to September 30, 2016 were selected. Based on Robson classification system, changes in the rate of caesarean delivery as well as its relationship with two-child policy and infant sex ratio were analyzed. Results: The overall caesarean section rate gradually decreased from 66.9% to 44.2% during the past six years. Respectively, the caesarean section rate in primiparae with singleton term babies decreased to 32.1% and the rate in multiparas without uterine scar decreased to 14.2%, and the rate in premature delivery decreased to 22.9%, the differences were significant (P<0.01). The proportion of vaginal delivery (R1, R3), multiparas with uterine scar (R5) and twins pregnancy (R8) increased. the differences were significant (P<0.01). The annual overall newly-born sex ratio ranged from 110∶100 to 128∶100. In group R1, more babies were girls, the proportion was stable, more women with premature delivery and multiparas had boy babies, but the boy babies by multiparas without uterine scar obviously decreased in the last 2 years. Conclusions: Primiparae with singleton head birth, multipara without uterine scar and women with premature deliveries are the key population in the effort of reduction of caesarean section rate. The caesarean section rate and proportion were unstable in multiparas with uterine scar, breech deliveries and twin deliveries. The application of Robson classification system can improve the comparability of the surveillance data.

CDK20 interacts with KEAP1 to activate NRF2 and promotes radiochemoresistance in lung cancer cells

Radiochemoresistance is considered the main cause of local recurrence and distant metastasis in lung cancer. However, the underlying mechanisms of radiochemoresistance remain to be uncovered. In this study, we determine the functions of cell cycle-related kinase (CDK20) in radiochemoresistance. CDK20 is a newly identified protein kinase, which plays critical roles in cell growth and proliferation in several types of cancer. Using tandem affinity purification technology, we provide evidences that CDK20 binds to the ubiquitin ligase Kelch-like ECH-associated protein 1 (KEAP1), which targets transcriptional factor nuclear factor erythroid-2-related factor 2 (NRF2) for degradation. We show that this interaction is mediated by an evolutionarily conserved ETGE motif on CDK20. Furthermore, we demonstrate that CDK20 competes with NRF2 for KEAP1 binding, enhances the transcriptional activity of NRF2 and lowers the cellular reactive oxygen species level. Moreover, CDK20-depleted cells display impaired cell proliferation, defective G2/M arrest and increased radiochemosensitivity in lung cancer. These phenotypes induced by CDK20 knockdown are partially dependent on NRF2 inactivation. More importantly, CDK20 is overexpressed in human lung cancer tissues, as determined by immunostaining. Collectively, our results suggest that CDK20 positively modulate the KEAP1-NRF2 cytoprotective pathway to regulate tumor progression and radiochemoresistance, implying that CDK20 is a novel, promising therapeutic target for lung cancer.