FASTA and FASTQ are basic and ubiquitous formats for storing nucleotide and protein sequences. Common manipulations of FASTA/Q file include converting, searching, filtering, deduplication, splitting, shuffling, and sampling. Existing tools only implement some of these manipulations, and not particularly efficiently, and some are only available for certain operating systems. Furthermore, the complicated installation process of required packages and running environments can render these programs less user friendly. This paper describes a cross-platform ultrafast comprehensive toolkit for FASTA/Q processing. SeqKit provides executable binary files for all major operating systems, including Windows, Linux, and Mac OSX, and can be directly used without any dependencies or pre-configurations. SeqKit demonstrates competitive performance in execution time and memory usage compared to similar tools. The efficiency and usability of SeqKit enable researchers to rapidly accomplish common FASTA/Q file manipulations. SeqKit is open source and available on Github at https://github.com/shenwei356/seqkit.

The common carp, Cyprinus carpio, is one of the most important cyprinid species and globally accounts for 10% of freshwater aquaculture production. Here we present a draft genome of domesticated C. carpio (strain Songpu), whose current assembly contains 52,610 protein-coding genes and approximately 92.3% coverage of its paleotetraploidized genome (2n = 100). The latest round of whole-genome duplication has been estimated to have occurred approximately 8.2 million years ago. Genome resequencing of 33 representative individuals from worldwide populations demonstrates a single origin for C. carpio in 2 subspecies (C. carpio Haematopterus and C. carpio carpio). Integrative genomic and transcriptomic analyses were used to identify loci potentially associated with traits including scaling patterns and skin color. In combination with the high-resolution genetic map, the draft genome paves the way for better molecular studies and improved genome-assisted breeding of C. carpio and other closely related species.

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Colistin is considered to be an antimicrobial of last-resort for the treatment of multidrug-resistant Gram-negative bacterial infections. The recent global dissemination of mobilized colistin resistance (mcr) genes is an urgent public health threat. An accurate estimate of the global prevalence of mcr genes, their reservoirs and the potential pathways for human transmission are required to implement control and prevention strategies, yet such data are lacking. Publications from four English (PubMed, Scopus, the Cochrane Database of Systematic Reviews and Web of Science) and two Chinese (CNKI and WANFANG) databases published between 18 November 2015 and 30 December 2018 were identified. In this systematic review and meta-analysis, the prevalence of mcr genes in bacteria isolated from humans, animals, the environment and food products were investigated. A total of 974 publications were identified. 202 observational studies were included in the systematic review and 71 in the meta-analysis. mcr genes were reported from 47 countries across six continents and the overall average prevalence was 4.7% (0.1–9.3%). China reported the highest number of mcr-positive strains. Pathogenic Escherichia coli (54%), isolated from animals (52%) and harboring an IncI2 plasmid (34%) were the bacteria with highest prevalence of mcr genes. The estimated prevalence of mcr-1 pathogenic E. coli was higher in food-animals than in humans and food products, which suggests a role for foodborne transmission. This study provides a comprehensive assessment of prevalence of the mcr gene by source, organism, genotype and type of plasmid.

In a worldwide collaborative effort, 19,630 Y-chromosomes were sampled from 129 different populations in 51 countries. These chromosomes were typed for 23 short-tandem repeat (STR) loci (DYS19, DYS389I, DYS389II, DYS390, DYS391, DYS392, DYS393, DYS385ab, DYS437, DYS438, DYS439, DYS448, DYS456, DYS458, DYS635, GATAH4, DYS481, DYS533, DYS549, DYS570, DYS576, and DYS643) and using the PowerPlex Y23 System (PPY23, Promega Corporation, Madison, WI). Locus-specific allelic spectra of these markers were determined and a consistently high level of allelic diversity was observed. A considerable number of null, duplicate and off-ladder alleles were revealed. Standard single-locus and haplotype-based parameters were calculated and compared between subsets of Y-STR markers established for forensic casework. The PPY23 marker set provides substantially stronger discriminatory power than other available kits but at the same time reveals the same general patterns of population structure as other marker sets. A strong correlation was observed between the number of Y-STRs included in a marker set and some of the forensic parameters under study. Interestingly a weak but consistent trend toward smaller genetic distances resulting from larger numbers of markers became apparent.

A dangerous cytokine storm occurs in the SARS involving in immune disorder, but many aspects of the pathogenetic mechanism remain obscure since its outbreak. To deeply reveal the interaction of host and SARS-CoV, based on the basic structural feature of pathogen-associated molecular pattern, we created a new bioinformatics method for searching potential pathogenic molecules and identified a set of SARS-CoV specific GU-rich ssRNA fragments with a high-density distribution in the genome. In vitro experiments, the result showed the representative SARS-CoV ssRNAs had powerful immunostimulatory activities to induce considerable level of pro-inflammatory cytokine TNF-a, IL-6 and IL-12 release via the TLR7 and TLR8, almost 2-fold higher than the strong stimulatory ssRNA40 that was found previously from other virus. Moreover, SARS-CoV ssRNA was able to cause acute lung injury in mice with a high mortality rate in vivo experiment. It suggests that SARS-CoV specific GU-rich ssRNA plays a very important role in the cytokine storm associated with a dysregulation of the innate immunity. This study not only presents new evidence about the immunopathologic damage caused by overactive inflammation during the SARS-CoV infection, but also provides a useful clue for a new therapeutic strategy.

The emergence of novel plasmid-mediated resistance genes constitutes a great public concern. Recently, mobile tet(X) variants were reported in diverse pathogens from different sources. However, the diversity of tet(X)-bearing plasmids remains largely unknown. In this study, the phenotypes and genotypes of all the tet(X)-positive tigecycline-resistant strains isolated from a slaughterhouse in China were characterized by antimicrobial susceptibility testing, conjugation, pulsed-field gel electrophoresis with S1 nuclease (S1-PFGE), and PCR. The diversity and polymorphism of tet(X)-harboring strains and plasmidomes were investigated by whole-genome sequencing (WGS) and single-plasmid-molecule analysis. Seventy-four tet(X4)-harboring Escherichia coli strains and one tet(X6)-bearing Providencia rettgeri strain were identified. The tet(X4)-bearing elements in 27 strains could be transferred to the recipient strain via plasmids. All tet(X4)-bearing plasmids isolated in this study and 15 tet(X4)-bearing plasmids reported online were analyzed. tet(X4)-bearing plasmids ranged from 9 to 294 kb and were categorized as ColE2-like, IncQ, IncX1, IncA/C2, IncFII, IncFIB, and hybrid plasmids with different replicons. The core tet(X4)-bearing genetic contexts were divided into four major groups: ISCR2-tet(X4)-abh, △ISCR2-abh-tet(X4)-ISCR2, ISCR2-abh-tet(X4)-ISCR2-virD2-floR, and abh-tet(X4)-ISCR2-yheS-cat-zitR-ISCR2-virD2-floR. Tandem repeats of tet(X4) were universally mediated by ISCR2. Different tet(X)-bearing strains existed in the same microbiota. Reorganization of tet(X4)-bearing multidrug resistance plasmids was found to be mediated by IS26 and other homologous regions. Finally, single-plasmid-molecule analysis captured the heterogenous state of tet(X4)-bearing plasmids. These findings significantly expand our knowledge of the tet(X)-bearing plasmidome among microbiotas, which establishes a baseline for investigating the structure and diversity of human, animal, and environmental tigecycline resistomes. Characterization of tet(X) genes among different microbiotas should be performed systematically to understand the evolution and ecology. IMPORTANCE Tigecycline is an expanded-spectrum tetracycline used as a last-resort antimicrobial for treating infections caused by superbugs such as carbapenemase-producing or colistin-resistant pathogens. Emergence of the plasmid-mediated mobile tigecycline resistance gene tet(X4) created a great public health concern. However, the diversity of tet(X4)-bearing plasmids and bacteria remains largely uninvestigated. To cover this knowledge gap, we comprehensively identified and characterized the tet(X)-bearing plasmidome in different sources using advanced sequencing technologies for the first time. The huge diversity of tet(X4)-bearing mobile elements demonstrates the high level of transmissibility of the tet(X4) gene among bacteria. It is crucial to enhance stringent surveillance of tet(X) genes in animal and human pathogens globally.

Targeted insertion of transgenes at predetermined plant genomic safe harbors provides a desirable alternative to insertions at random sites achieved through conventional methods. Most existing cases of targeted gene insertion in plants have either relied on the presence of a selectable marker gene in the insertion cassette or occurred at low frequency with relatively small DNA fragments (<1.8 kb). Here, we report the use of an optimized CRISPR-Cas9-based method to achieve the targeted insertion of a 5.2 kb carotenoid biosynthesis cassette at two genomic safe harbors in rice. We obtain marker-free rice plants with high carotenoid content in the seeds and no detectable penalty in morphology or yield. Whole-genome sequencing reveals the absence of off-target mutations by Cas9 in the engineered plants. These results demonstrate targeted gene insertion of marker-free DNA in rice using CRISPR-Cas9 genome editing, and offer a promising strategy for genetic improvement of rice and other crops.