Prevalence of Arcobacter and other pathogenic bacteria in river water in Nepal

Published: 10 July 2019This study aims to determine the diversity of pathogenic bacteria in the Bagmati River, Nepal, during a one-year period. A total of 18 river water samples were collected from three sites (n = 6 per site) along the river. Bacterial DNA, which were extracted from the water samples, were analyzed for bacterial 16S rRNA genes by next-generation sequencing for 13 of 18 samples, and by quantitative PCR targeting Arcobacter for all 18 samples. The 16S rRNA sequencing identified an average of 97,412 ± 35,909 sequences/sample, which were then categorized into 28 phyla, 61 classes, and 709 bacterial genera. Eighteen (16%) genera of 111 potential pathogenic bacteria were detected with abundance ratios of >1%; Arcobacter, Acinetobacter, and Prevotella were the dominant genera. The Arcobacter abundance ratios were 28.6% (n = 1), 31.3 ± 15.8% (n = 6), and 31.8 ± 17.2% (n = 6) at the upstream, midstream, and downstream sites, respectively. Arcobacter was detected in 14 (78%) of 18 samples tested, with concentrations ranging from 6.7 to 10.7 log10 copies/100 mL, based on quantitative PCR. Our results demonstrate the poor bacterial quality of the Bagmati River water, suggesting a need for implementing more measures to reduce fecal contamination in the river water.Rajani Ghaju Shrestha, Sarmila Tandukar, Dinesh Bhandari, Samendra P. Sherchan, Yasuhiro Tanaka, Jeevan B. Sherchand and Eiji Haramot

Detection of Cryptosporidium, Giardia, fecal indicator bacteria, and total bacteria in commercial jar water in Kathmandu Valley, Nepal

Introduction: Jar water is a convenient and common source of drinking water in the Kathmandu Valley. However, studies including detailed microbial analyses of this source of potable water are lacking. In this study, jar water samples were examined for the occurrence of Cryptosporidium, Giardia, fecal indicator bacteria, and total bacteria. Methods: Thirty different brands of jars were collected in September 2014. Escherichia coli and total coliforms w ere determined using a Colilert reagent. Ten of the 30 brands w ere selected to test for Cryptosporidium, Giardia, and total bacteria. Bacterial DNA extraction from water samples w as performed using the Cica Geneus DNA Extraction Kit, follow ed by quantitative polymerase chain reaction (qPCR) targeting the 16S rRNA gene of bacterial DNA. Protozoan detection was accomplished by concentrating the samples using the electronegative membrane vortex method, followed by immunomagnetic separation and fluorescent staining. Results: E. coli w as detected in 10% of the samples, with a maximum concentration of 2 most probable number (MPN)/100 mL, whereas total coliforms were detected in 97% of the samples, with a maximum and mean concentration of 7.3 × 10 2 and 3.8 × 10 1 MPN/100 mL, respectively. Total coliforms concentrations in 40% of the samples ranged from 10 2 to 10 3 MPN/100 mL. Cryptosporidium and Giardia w ere not detected in any of the tested samples. Concentrations of total bacteria in the samples ranged from 10 4 to 10 6 cells/100 mL. Conclusions: Ninety-seven percent of the jar water brands were unsuitable for drinking without proper treatment based on the guideline values of the National Drinking Water Quality Standards (NDW Q S) of Nepal. There is no guideline value for total bacteria in NDW Q S however, high concentrations can be indicative of poor control on regrowth of bacteria and recontamination or inefficient water treatment methods.Malla B, Ghaju Shrestha R, Bhandari D, Tandukar S, Shrestha S, Yoshinaga H, Inoue D, Sei K, Nishida K, Tanaka Y, Sherchand JB, Haramoto

Maternal Wnt/β-Catenin Signaling Coactivates Transcription through NF-κB Binding Sites during Xenopus Axis Formation

Maternal Wnt/β-Catenin signaling establishes a program of dorsal-specific gene expression required for axial patterning in Xenopus. We previously reported that a subset of dorsally expressed genes depends not only on Wnt/β-Catenin stimulation, but also on a MyD88-dependent Toll-like receptor/IL1-receptor (TLR/IL1-R) signaling pathway. Here we show that these two signal transduction cascades converge in the nucleus to coactivate gene transcription in blastulae through a direct interaction between β-Catenin and NF-κB proteins. A transdominant inhibitor of NF-κB, ΔNIκBα, phenocopies loss of MyD88 protein function, implicating Rel/NF-κB proteins as selective activators of dorsal-specific gene expression. Sensitive axis formation assays in the embryo demonstrate that dorsalization by Wnt/β-Catenin requires NF-κB protein activity, and vice versa. Xenopus nodal-related 3 (Xnr3) is one of the genes with dual β-Catenin/NF-κB input, and a proximal NF-κB consensus site contributes to the regional activity of its promoter. We demonstrate in vitro binding of Xenopus β-Catenin to several XRel proteins. This interaction is observed in vivo upon Wnt-stimulation. Finally, we show that a synthetic luciferase reporter gene responds to both endogenous and exogenous β-Catenin levels in an NF-κB motif dependent manner. These results suggest that β-Catenin acts as a transcriptional co-activator of NF-κB-dependent transcription in frog primary embryonic cells

Genome evolution in the allotetraploid frog Xenopus laevis

To explore the origins and consequences of tetraploidy in the African clawed frog, we sequenced the Xenopus laevis genome and compared it to the related diploid X. tropicalis genome. We characterize the allotetraploid origin of X. laevis by partitioning its genome into two homoeologous subgenomes, marked by distinct families of ???fossil??? transposable elements. On the basis of the activity of these elements and the age of hundreds of unitary pseudogenes, we estimate that the two diploid progenitor species diverged around 34 million years ago (Ma) and combined to form an allotetraploid around 17-18 Ma. More than 56% of all genes were retained in two homoeologous copies. Protein function, gene expression, and the amount of conserved flanking sequence all correlate with retention rates. The subgenomes have evolved asymmetrically, with one chromosome set more often preserving the ancestral state and the other experiencing more gene loss, deletion, rearrangement, and reduced gene expression.ope