RNA-encoding Genes Research Articles

Dysregulation of murine long noncoding single-cell transcriptome in nonalcoholic steatohepatitis and liver fibrosis.

LncRNAs comprise a heterogeneous class of RNA-encoding genes typified by low expression, nuclear enrichment, high tissue-specificity, and functional diversity, but the vast majority remain uncharacterized. Here, we assembled the mouse liver noncoding transcriptome from >2000 bulk RNA-seq samples and discovered 48,261 liver-expressed lncRNAs, a majority novel. Using these lncRNAs as a single-cell transcriptomic reference set, we elucidated lncRNA dysregulation in mouse models of high fat diet-induced nonalcoholic steatohepatitis and carbon tetrachloride-induced liver fibrosis. Trajectory inference analysis revealed lncRNA zonation patterns across the liver lobule in each major liver cell population. Perturbations in lncRNA expression and zonation were common in several disease-associated liver cell types, including nonalcoholic steatohepatitis-associated macrophages, a hallmark of fatty liver disease progression, and collagen-producing myofibroblasts, a central feature of liver fibrosis. Single-cell-based gene regulatory network analysis using bigSCale2 linked individual lncRNAs to specific biological pathways, and network-essential regulatory lncRNAs with disease-associated functions were identified by their high network centrality metrics. For a subset of these lncRNAs, promoter sequences of the network-defined lncRNA target genes were significantly enriched for lncRNA triplex formation, providing independent mechanistic support for the lncRNA-target gene linkages predicted by the gene regulatory networks. These findings elucidate liver lncRNA cell-type specificities, spatial zonation patterns, associated regulatory networks, and temporal patterns of dysregulation during hepatic disease progression. A subset of the liver disease-associated regulatory lncRNAs identified have human orthologs and are promising candidates for biomarkers and therapeutic targets.

Dietary supplement of mushrooms promotes SCFA production and moderately associates with IgA production: A pilot clinical study.

Mushrooms are rich in dietary fiber, and fiber intake has been reported to increase the levels of short-chain fatty acids (SCFAs). It has also been reported that SCFAs promote immunoglobulin A (IgA) production, indicating involvement in systemic immunity. The objective of this study was to evaluate the effects of mushroom consumption on the amount of intestinal IgA. We also aimed to comprehensively evaluate the gut microbiota and intestinal metabolome and to conduct an exploratory analysis of their relationship with IgA. Healthy adults (n = 80) were enrolled in a parallel group trial. Participants consumed a diet with mushrooms or a placebo diet once daily for 4 weeks. Gut microbiota profiles were assessed by sequencing the bacterial 16S ribosomal RNA-encoding gene. Intestinal metabolome profiles were analyzed using capillary electrophoresis-time of flight mass spectrometry (CE-TOFMS). Mushroom consumption tended to increase IgA levels at 4 weeks of consumption compared to those in the control group (p = 0.0807; Hedges' g = 0.480). The mushroom group had significantly higher levels of intestinal SCFAs, such as butyrate and propionate, than the control group (p = 0.001 and 0.020; Hedges' g = 0.824 and 0.474, respectively). Correlation analysis between the changes in the amount of intestinal IgA and the baseline features of the intestinal environment showed that the increasing amount of intestinal IgA was positively correlated with the baseline levels of SCFAs (Spearman's R = 0.559 and 0.419 for butyrate and propionate, respectively). Consumption of mushrooms significantly increased the intestinal SCFAs and IgA in some subjects. The increase in intestinal IgA levels was more prominent in subjects with higher SCFA levels at baseline. This finding provides evidence that mushroom alters the intestinal environment, but the intensity of the effect still depends on the baseline intestinal environment. This trial was registered at www.umin.ac.jp as UMIN000043979.

Investigating the Biocontrol Potential of the Natural Microbiota of the Apple Blossom.

Erwinia amylovora, the causative agent of fire blight, leads to important economic losses of apple and pear crops worldwide. This study aimed to investigate the potential of the resident microbiota of the apple blossom in combatting plant disease-causing organisms, with a focus on controlling fire blight. We obtained 538 isolates from sites around Canton Zurich, which we tested for activity against Pectobacterium carotovorum and E. amylovora. We also evaluated the isolates' activity against oomycete and fungal pathogens. Nine isolates showed activity against P. carotovorum, and eight of these against E. amylovora. Furthermore, 117 showed antifungal, and 161 anti-oomycete, activity. We assigned genera and in some cases species to 238 of the isolates by sequencing their 16S RNA-encoding gene. Five strains showed activity against all pathogens and were tested in a detached apple model for anti-E. amylovora activity. Of these five strains, two were able to antagonize E. amylovora, namely Bacillus velezensis #124 and Pantoea agglomerans #378. We sequenced the P. agglomerans #378 genome and analyzed it for secondary metabolite clusters using antiSMASH, revealing the presence of a putative bacteriocin cluster. We also showed that B. velezensis #124 exhibits strong activity against three different fungi and two oomycetes in vitro, suggesting a broader capacity for biocontrol. Our results showcase the protective potential of the natural apple blossom microbiota. We isolated two candidate biocontrol strains from apple blossoms, suggesting that they might persist at the most common entry point for the causative agent of fire blight. Furthermore, they are probably already part of the human diet, suggesting they might be safe for consumption, and thus are promising candidates for biocontrol applications.

Complete Mitochondrial Genome Sequences of Korean Phytophthora infestans Isolates and Comparative Analysis of Mitochondrial Haplotypes.

Potato late blight caused by Phytophthora infestans is a destructive disease in Korea. To elucidate the genomic variation of the mitochondrial (mt) genome, we assembled its complete mt genome and compared its sequence among different haplotypes. The mt genome sequences of four Korean P. infestans isolates were revealed by Illumina HiSeq. The size of the circular mt genome of the four major genotypes, KR_1_A1, KR_2_A2, SIB-1, and US-11, was 39,872, 39,836, 39,872, and 39,840 bp, respectively. All genotypes contained the same 61 genes in the same order, comprising two RNA-encoding genes, 16 ribosomal genes, 25 transfer RNA, 17 genes encoding electron transport and ATP synthesis, 11 open reading frames of unknown function, and one protein import-related gene, tatC. The coding region comprised 91% of the genome, and GC content was 22.3%. The haplotypes were further analyzed based on sequence polymorphism at two hypervariable regions (HVRi), carrying a 2 kb insertion/deletion sequence, and HVRii, carrying 36 bp variable number tandem repeats (VNTRs). All four genotypes carried the 2 kb insertion/deletion sequence in HVRi, whereas HVRii had two VNTRs in KR_1_A1 and SIB-1 but three VNTRs in US-11 and KR_2_A2. Minimal spanning network and phylogenetic analysis based on 5,814 bp of mtDNA sequences from five loci, KR_1_A1 and SIB-1 were classified as IIa-6 haplotype, and isolates KR_1_A2 and US-11 as haplotypes IIa-5 and IIb-2, respectively. mtDNA sequences of KR_1_A1 and SIB-1 shared 100% sequence identity, and both were 99.9% similar to those of KR_2_A2 and US-11.

Compositional Alterations of the Nasal Microbiome and Staphylococcus aureus-Characterized Dysbiosis in the Nasal Mucosa of Patients With Allergic Rhinitis.

Host-microbial commensalism can shape the innate immune response in the nasal mucosa, and the microbial characteristics of nasal mucus directly impact the mechanisms of the initial allergic responses in the nasal epithelium. We sought to determine alterations of the microbial composition in the nasal mucus of patients with allergic rhinitis (AR) and to elucidate the interplay between dysbiosis of the nasal microbiome and allergic inflammation. In total, 364,923 high-quality bacterial 16S ribosomal RNA-encoding gene sequence reads from 104 middle turbinate mucosa samples from healthy participants and patients with AR were obtained and analyzed using the Quantitative Insights into Microbial Ecology pipeline. We analyzed the microbiota in samples of nasal mucus from patients with AR (n=42) and clinically healthy participants (n=30). The Proteobacteria (Ralstonia genus) and Actinobacteria (Propionibacterium genus) phyla were predominant in the nasal mucus of healthy subjects, whereas the Firmicutes (Staphylococcus genus) phylum was significantly abundant in the nasal mucus of patients with AR. In particular, the Ralstonia genus was significantly dominant in the clinically healthy subjects. Additional pyrosequencing data from 32 subjects (healthy participants: n=15, AR patients: n=17) revealed a greater abundance of Staphylococcus epidermidis, Corynebacterium accolens, and Nocardia coeliaca, accounting for 41.55% of mapped sequences in the nasal mucus of healthy participants. Dysbiosis of the nasal microbiome was more pronounced in patients with AR, and Staphylococcus aureus exhibited the greatest abundance (37.69%) in their nasal mucus, in association with a positive response to house dust mites and patients' age and height. This study revealed alterations in the nasal microbiome in the nasal mucus of patients with AR at the levels of microbial genera and species. S. aureus-dominant dysbiosis was distinctive in the nasal mucus of patients with AR, suggesting a role of host-microbial commensalism in allergic inflammation.

Metagenome-assembled genome (MAG) of Oceancaulis alexandrii NP7 isolated from Mediterranean Sea polluted marine sediments and its bioremediation potential.

Oceanicaulis alexandrii strain NP7 is a marine bacterium which belongs to the Hyphomonadaceae family and was isolated from sediments highly contaminated with metals and polycyclic aromatic hydrocarbons released for decades by industrial activities in the Gulf of Naples (Mediterranean Sea). Here, we report the partial genome sequence and annotation of O. alexandrii strain NP7 that contains a chromosome of 2,954,327 bp and encodes for 2914 predicted coding sequences (CDSs) and 44 RNA-encoding genes. Although the presence of some CDSs for genes involved in hydrocarbon degradation processes (e.g., alkB) have already been described in the literature associated with the Oceanicaulis, this is the first time that more than 100 genes involved in metal detoxification processes and hydrocarbon degradation are reported belonging to this genus. The presence of a heterogeneous set of genes involved in stress response, hydrocarbon degradation, heavy metal resistance, and detoxification suggests a possible role for O. alexandrii NP7 in the bioremediation of these highly contaminated marine sediments.

First report of 'Candidatus Phytoplasma trifolii' associated with leaf reddening and upright growth in pears (Pyrus communis L.)

The natural occurrence of 'Candidatus Phytoplasma trifolii' in pear trees (Pyrus communis Linnaeus) is reported here for the first time. In 2017, a total of thirty-five pear trees, two of them exhibiting leaf rolling along the midvein, reddening, bushy appearance, and upright growth symptoms were sampled in different locations in Van province, Turkey. The total deoxyribonucleic acid was extracted from symptomatic and asymptomatic plants. The purified DNA served as a template in nested polymerase chain reaction (nested-PCR) assays, performed to amplify 16S rRNA sequences using universal primer pairs (R16mF2/R16mR1 and R16F2n/R16R2). The resulting PCR products were then cloned into a pGEM T-Easy vector and sequenced bidirectionally. The phytoplasma strain, group, and subgroup identity were determined using the in silico restriction fragment length polymorphism (RFLP) analysis of the 16S ribosomal RNA-encoding gene sequences profiling with seventeen distinct restriction enzymes. Of the thirty-five pear samples, only two yielded 1 256 bp and 1 258 bp DNA fragments and were designated as Van-Pr3 (Acc. No. MH709141) and Van-Pr4 (Acc. No. MH730561), respectively. Based on the in silico virtual RFLP pattern analysis of the 16S rRNA sequences, we confirmed the presence of 'Ca. P. trifolii' belonging to the clover proliferation group and both identified phytoplasmas were identical with the similarity coefficient of 1.00 to the reference pattern of 16Sr group VI, subgroup A (Acc. No. AY390261). Here we report that the pear tree is an alternate host of the 'Ca. P. trifolii'.

Cellulomonas taurus sp. nov., a novel bacteria with multiple hydrolase activity isolated from livestock, and potential application in wastewater treatment.

A Gram-positive, smooth, sub-transparent, faint yellow,0.5-0.7µm diameter, rod shaped aerobic or facultative aerobic strain P40-2Twas isolated from livestock farms in Northeast China. Strain P40-2T grew at 25-40°C (optimum 30-38 °C), and in 0-4% (w/v) NaCl (optimum 0%) in LB medium. Based on 16S rRNA gene sequence analysis, strain P40-2T belongs to the class Cellulomonas and is most closely related to C. denverensis strain W6929, C. pakistanensis strain NCCP-11and C. hominis strain CE40.DNA-DNA hybridization rate of strain P40-2T was 29%, and the ANI with C.denverensisstrainW6929 was 85.33%. The genome is 3437431bp long with a G + C content of 71.99%. Of the 3177 predicted genes, 3119 were protein-coding genes and 58 were RNA encoding genes. The chemotaxonomic data: menaquinone was MK-9(H4), anteiso-C15: 0, C16:0 and anteiso-C17: 0 were the major cellular fatty acids, and the main cell-wall amino acids were ornithine,alanine, glycine and glutamate. The cell wall peptidogly can sugars included glucose, rhamnose, galactose and mannose. The polar lipid present were DPG, PG, PE, and PIM. On the basis of DNA-DNA relatedness, phylogenetic position, complete genome sequence and physiological characteristics, strain P40-2T can be differentiated from other species of the genus Cellulomonas with validly published names and thus represents a novel species, for which the name Cellulomonas taurus is proposed. The type strain is Cellulomonas taurus P40-2T (= CGMCC No.1.17732T).The acute toxicity test in mice showed that LD50 of strain P40-2T was rather high with 1.5 × 1011CFU/mouse, which indicated low pathogenicity. Drug susceptibility showed that strainP40-2T was resistant to most antibiotics and only sensitive to six antibiotics. Strain P40-2T contained a variety of hydrolytic enzymes including the ability to hydrolyze cellulose, β-glucan, chitin, xylan, and casein. Microbial flocculant MBF-P40 for sewage was prepared with strain P40-2T, after strain P40-2T was confirmed that had good flocculation effect. MBF-P40 was used to prepare flocculation rate of 99.40%. MBF-P40 treatmented sewage from eight different sources. Flocculation rate for pig farm wastewater was 96.07%, COD removal rate is 71.05%, ammonia nitrogen removal rate is 18.22%. The result shows that MBF-P40 has a good flocculation effect, and good prospect of development and application for wastewater treatment.

6S-1 RNA Contributes to Sporulation and Parasporal Crystal Formation in Bacillus thuringiensis.

6S RNA is a kind of high-abundance non-coding RNA that globally regulates bacterial transcription by interacting with RNA polymerase holoenzyme. Through bioinformatics analysis, we found that there are two tandem 6S RNA-encoding genes in the genomes of Bacillus cereus group bacteria. Using Bacillus thuringiensis BMB171 as the starting strain, we have explored the physiological functions of 6S RNAs, and found that the genes ssrSA and ssrSB encoding 6S-1 and 6S-2 RNAs were located in the same operon and are co-transcribed as a precursor that might be processed by specific ribonucleases to form mature 6S-1 and 6S-2 RNAs. We also constructed two single-gene deletion mutant strains ΔssrSA and ΔssrSB and a double-gene deletion mutant strain ΔssrSAB by means of the markerless gene knockout method. Our data show that deletion of 6S-1 RNA inhibited the growth of B. thuringiensis in the stationary phase, leading to lysis of some bacterial cells. Furthermore, deletion of 6S-1 RNA also significantly reduced the spore number and parasporal crystal content. Our work reveals that B. thuringiensis 6S RNA played an important regulatory role in ensuring the sporulation and parasporal crystal formation.

RNA, Genome Output and Input.

RNA, the transcriptional output of genomes, not only templates protein synthesis or directly engages in catalytic functions, but can feed back to the genome and serve as regulatory input for gene expression. Transcripts affecting the RNA abundance of other genes act by mechanisms similar to and in concert with protein factors that control transcription. Through recruitment or blocking of activating and silencing complexes to specific genomic loci, RNA and protein factors can favor transcription or lower the local gene expression potential. Most regulatory proteins enter nuclei from all directions to start the search for increased affinity to specific DNA sequences or to other proteins nearby genuine gene targets. In contrast, RNAs emerge from spatial point sources within nuclei, their encoding genes. A transcriptional burst can result in the local appearance of multiple nascent RNA copies at once, in turn increasing local nucleic acid density and RNA motif abundance before diffusion into the nuclear neighborhood. The confined initial localization of regulatory RNAs causing accumulation of protein co-factors raises the intriguing possibility that target specificity of non-coding, and probably coding, RNAs is achieved through gene/RNA positioning and spatial proximity to regulated genomic regions. Here we review examples of positional cis conservation of regulatory RNAs with respect to target genes, spatial proximity of enhancer RNAs to promoters through DNA looping and RNA-mediated formation of membrane-less structures to control chromatin structure and expression. We speculate that linear and spatial proximity between regulatory RNA-encoding genes and gene targets could possibly ease the evolutionary pressure on maintaining regulatory RNA sequence conservation.

Occurrence of ‘Candidatus Phytoplasma omanense’-related strains and other phytoplasmas in Sophora alopecuroides plants showing dwarfing and yellowing

Sophora alopecuroides dwarfing and yellowing symptoms were observed at the edge of several Damaneh and Fereydun Shahr (Isfahan province, Iran) fields. Polymerase chain reaction using primers P1/P7 and nested PCR using the same primers followed by R16mF2/R16mR2 and R16F2n/R16R2 primer pairs amplified the 16S ribosomal RNA-encoding gene in all the symptomatic plants tested, but not in the asymptomatic ones. RFLP analysis of R16F2n/R16R2 amplicons with AluI, HaeIII, HhaI, HpaI, HpaII, RsaI, MseI and TaqI restriction enzymes showed profiles referable to 16SrII, 16SrVI, 16SrIX, 16SrXII and 16SrXXIX phytoplasma ribosomal groups indicating also the presence of mixed infection in several samples. The identity percentage and the phylogeny obtained after direct sequencing of selected 16S rRNA-encoding gene sequences (R16F2n/R2 amplicons) from symptomatic S. alopecuroides confirmed the presence of phytoplasma strains related to ‘Candidatus Phytoplasma omanense’ (group 16SrXXIX), ‘Ca. P. australasia’ (group 16SrII), and ‘Ca. P. trifolii’ (16SrVI). Moreover, in a few samples/amplicons, 16SrXII-A, 16SrIX-H, 16SrVI-F and 16SrXXIX-A phytoplasma subgroups were identified by real and virtual RFLP analyses. The other phytoplasmas detected were classified in subgroups 16SrII-D and 16SrVI-A. This is the first report of the presence of 16SrII and 16SrXXIX phytoplasma groups and of mixed infection of phytoplasma strains belonging to groups 16SrII, 16SrVI, 16SrIX, 16SrXII and 16SrXXIX in S. alopecuroides worldwide.

Characteristics and complete genome sequence of the virulent Vibrio alginolyticus phage VAP7, isolated in Hainan, China

A novel Vibrio alginolyticus phage, VAP7, was isolated from seawater collected from Sanya, Hainan province, China. Whole-genome sequencing analysis revealed that phage VAP7 has a linear, double-stranded DNA genome of 144,685bp with an average G+C content of 41.9% and a high degree of sequence similarity to Vibrio phage VP-1. Annotation results identified 193 open reading frames and one transfer RNA-encoding gene in the phage genome. The morphology and the results of phylogenetic analysis suggest that VAP7 should be classified as a new member of the family Ackermannviridae. Moreover, phage VAP7 grew over a wide pH (5.0-10.0) and temperature (4-40°C) range. Host-range experiments revealed that VAP7 could infect 31Vibrio alginolyticus strains. Thus, VAP7 infecting Vibrio alginolyticus strains represents a potential new candidate for use in phage therapy.

Isolation and Characterization of a Novel Bacteriophage Infecting Carbapenem-Resistant Klebsiella pneumoniae

A novel virulent phage, vB_KpnP_IME337, isolated from a hospital sewage in Beijing, China, that infects carbapenem-resistant Klebsiella pneumoniae KN2 capsular type was identified and characterized. Next-generation sequencing and genome analysis revealed that vB_KpnP_IME337 had a linear double-stranded genome with a length of 44,266 base pairs and G+C content of 53.7%. Fifty-two putative open reading frames were identified, and no transfer RNA-encoding genes were detected. BLASTn analysis revealed that phage vB_KpnP_IME337 had the highest sequence similarity with Klebsiella phage phiBO1E, with genome coverage of 79%. Based on morphology, phage vB_KpnP_IME337 was determined to belong to the family Podoviridae of the order Caudovirales. It was shown that phage vB_KpnP_IME337 had an infection duration of ~ 90min and 10min latent period, and a highly specific to host strain. In conclusion, phage vB_KpnP_IME337 may be a promising alternative candidate to antibiotic treatment for controlling diseases caused by drug-resistant K. pneumoniae.

Mitochondrial genome mutations in mesenchymal stem cells derived from human dental induced pluripotent stem cells

Ethical and safety issues have rendered mesenchymal stem cells (MSCs) popular candidates in regenerative medicine, but their therapeutic capacity is lower than that of induced pluripotent stem cells (iPSCs). This study compared original, dental tissue-derived MSCs with re-differentiated MSCs from iPSCs (iPS-MSCs). CD marker expression in iPS-MSCs was similar to original MSCs. iPS-MSCs expressed higher in pluripotent genes, but lower levels in mesodermal genes than MSCs. In addition, iPS-MSCs did not form teratomas. All iPSCs carried mtDNA mutations; some shared with original MSCs and others not previously detected therein. Shared mutations were synonymous, while novel mutations were non-synonymous or located on RNA-encoding genes. iPS-MSCs also harbored mtDNA mutations transmitted from iPSCs. Selected iPS-MSCs displayed lower mitochondrial respiration than original MSCs. In conclusion, screening for mtDNA mutations in iPSC lines for iPS-MSCs can identify mutation-free cell lines for therapeutic applications.

The CpnClassiPhyR Is a Resource for cpn60 Universal Target-Based Classification of Phytoplasmas.

Phytoplasmas are plant-pathogenic bacteria that are associated with yield losses in many crop plants worldwide. Phytoplasma strain differentiation is accomplished using in silico restriction fragment length polymorphism (RFLP) analysis of 16S ribosomal RNA-encoding gene sequences, which has resulted in the definition of ribosomal groups and subgroups of phytoplasmas. Due to limitations associated with this approach, a complementary classification scheme was recently developed based on RFLP analysis of the single-copy, protein-encoding gene chaperonin-60 (cpn60). We present the CpnClassiPhyR, software that facilitates phytoplasma strain classification using both RFLP and automated phylogenetic analysis of cpn60 sequences. This software is available through a web interface at http://cpnclassiphyr.ca.

Revisiting Chaetoceros subtilis and C. subtilis var. abnormis (Bacillariophyceae), reinstating the latter as C. abnormis

:Chaetoceros is one of the most species-rich diatom genera, but about one-third to one-half of the taxa are considered synonyms, and a modern revision is needed on the basis of a combination of morphological and molecular data. Chaetoceros subtilis Cleve and C. subtilis var. abnormis (Proschkina-Lavrenko) Proschkina-Lavrenko were revisited in the present study. Monoclonal strains were established from the southeast Chinese coast. Morphology of vegetative cells and resting spores was observed using light microscopy, as well as scanning and transmission electron microscopy. The hypervariable D1–D3 region of the nuclear large-subunit ribosomal RNA-encoding gene (LSU ribosomal DNA) was sequenced for information on phylogenetic relationships. Species delineations were evaluated for the two taxa. Morphologically, C. subtilis var. abnormis was quite similar to C. subtilis, but differences were found in the number of thick terminal posterior setae, detailed structure and morphometric data of intercalary and thick setae, and several morphological differences were found in the resting spores. In phylogenetic analyses inferred from the LSU sequences, C. subtilis var. abnormis and C. subtilis formed well-separated sister taxa, which supported their morphological similarity and also their distinct differences. Their differences were supported by 42 base pairs, giving a genetic difference of 7.2%. Combined morphological and molecular data revealed that C. subtilis and C. subtilis var. abnormis were distinct species. We therefore reinstate the latter taxon as C. abnormis Proschkina-Lavrenko.

Nasal microbiota and symptom persistence in acute respiratory tract infections in infants.

Acute respiratory tract infections (ARI) in infancy have been implicated in the development of chronic respiratory disease, but the complex interplay between viruses, bacteria and host is not completely understood. We aimed to prospectively determine whether nasal microbiota changes occur between the onset of the first symptomatic ARI in the first year of life and 3 weeks later, and to explore possible associations with the duration of respiratory symptoms, as well as with host, environmental and viral factors.Nasal microbiota of 167 infants were determined at both time-points by 16S ribosomal RNA-encoding gene PCR amplification and subsequent pyrosequencing. Infants were clustered based on their nasal microbiota using hierarchical clustering methods at both time-points.We identified five dominant infant clusters with distinct microbiota at the onset of ARI but only three clusters after 3 weeks. In these three clusters, symptom persistence was overrepresented in the Streptococcaceae-dominated cluster and underrepresented in the cluster dominated by “Others” (p<0.001). Duration of symptoms was not associated with the type of respiratory virus.Infants with prolonged respiratory symptoms after their first ARI tend to exhibit distinct microbial compositions, indicating close microbiota–host interactions that seem to be of importance for symptom persistence and recovery.

Complete Genome Sequence of a Novel T7-Like Bacteriophage from a Pasteurella multocida Capsular Type A Isolate.

A novel virulent bacteriophage, vB_PmuP_PHB02 (phage PHB02), infecting Pasteurella multocida capsular type A strains, was isolated from wastewater from a swine farm in China. Phage PHB02 has a linear double-stranded DNA genome consisting of 38,670 base pairs (bp), with a G+C content of 40.8% and a 127-bp terminal redundancy. Forty-eight putative open reading frames were identified, and no transfer RNA-encoding genes were detected. The morphology and genomic structure of phage PHB02 resemble those of T7-like phages belonging to the family Podoviridae, of the order Caudovirales. Phage PHB02 was stable over a wide range of temperatures (4-50°C) and pH values (5.0-9.0), and lysed 30 of the 31 capsular-type-A P. multocida strains tested. Phage PHB02 had no effect on other bacterial species or on P. multocida strains belonging to capsular types D or F.

A Role for the Mutagenic DNA Self-Catalyzed Depurination Mechanism in the Evolution of 7SL-Derived RNAs.

The Alu element, the most prevalent SINE (short interspersed element) in the human genome, is one of the many RNA-encoding genes that evolved from the 7SL RNA gene. During analysis of the evolution of 7SL-derived RNAs, two distinct evolutionary intermediates capable of self-catalyzed DNA depurination (SDP) were identified. These SDP sequences spontaneously create apurinic sites that can result in increased mutagenesis due to their error-prone repair. This DNA self-depurination mechanism has been shown both in vitro and in vivo to lead to substitution and short frameshift mutations at a frequency that far exceeds their occurrence due to random errors in DNA replication. In both evolutionary intermediates, the same self-depurination sequence overlaps motifs necessary for successful transcription and SRP9/14 (signal recognition particle) binding; hence, mutations in this region could disrupt RNA activity. Yet, the 7SL-derived RNAs that arose from the elements capable of SDP show significant diversity in this region, and every new sequence retains the transcription and SRP9/14-binding motifs, even as it has lost the SDP sequence. While some (but not all) of the mutagenesis can be alternatively attributed to CpG decay, the very fact that the self-depurinating sequences are selectively discarded in all cases suggests that this was evolutionarily motivated to prevent further destructive mutagenesis by the SDP mechanism.

Draft genome sequence of an aminoglycoside-resistant RmtD2-producing Enterobacter cloacae subsp. cloacae ST395 in Brazil.

Enterobacter cloacae has recently emerged as an important agent of nosocomial infections owing to the dissemination of extended-spectrum β-lactamases and carbapenemases in this species. In this context, a rise in the therapeutic use of aminoglycosides was noticed, followed by the accelerated development of resistance mechanisms. In this study, we report the draft genome sequence of a multidrug-resistant E. cloacae subsp. cloacae strain (Ec2) isolated from an active surveillance culture of a patient with Chagas disease. Whole-genome sequencing (WGS) was performed using a Nextera XT DNA library and NextSeq platform. WGS analysis revealed the presence of 5527 coding genes, 62 RNA-encoding genes and 275 pseudogenes. Strain Ec2 belongs to sequence type 395 (ST395) and carries 22 transferable antibiotic resistance genes, comprising eight antimicrobial classes, including the rmtD2 gene conferring high-level aminoglycoside resistance. This draft genome can be used in comparative genomic analyses with different E. cloacae strains. In addition, it could help at elucidating epidemiological aspects regarding the dissemination of clinically relevant resistance genes.