Integrated analysis of long non-coding RNAs and mRNAs reveals the regulatory network of maize seedling root responding to salt stress

Background Long non-coding RNAs (lncRNAs) play important roles in response to abiotic stresses in plants, by acting as cis- or trans-acting regulators of protein-coding genes. As a widely cultivated crop worldwide, maize is sensitive to salt stress particularly at the seedling stage. However, it is unclear how the expressions of protein-coding genes are affected by non-coding RNAs in maize responding to salt tolerance. Results The whole transcriptome sequencing was employed to investigate the differential lncRNAs and target transcripts responding to salt stress between two maize inbred lines with contrasting salt tolerance. We developed a flexible, user-friendly, and modular RNA analysis workflow, which facilitated the identification of lncRNAs and novel mRNAs from whole transcriptome data. Using the workflow, 12,817 lncRNAs and 8,320 novel mRNAs in maize seedling roots were identified and characterized. A total of 742 lncRNAs and 7,835 mRNAs were identified as salt stress-responsive transcripts. Moreover, we obtained 41 cis- and 81 trans-target mRNA for 88 of the lncRNAs. Among these target transcripts, 11 belonged to 7 transcription factor (TF) families including bHLH, C2H2, Hap3/NF-YB, HAS, MYB, WD40, and WRKY. The above 8,577 salt stress-responsive transcripts were further classified into 28 modules by weighted gene co-expression network analysis. In the salt-tolerant module, we constructed an interaction network containing 79 nodes and 3081 edges, which included 5 lncRNAs, 18 TFs and 56 functional transcripts (FTs). As a trans-acting regulator, the lncRNA MSTRG.8888.1 affected the expressions of some salt tolerance-relative FTs, including protein-serine/threonine phosphatase 2C and galactinol synthase 1, by regulating the expression of the bHLH TF. Conclusions The contrasting genetic backgrounds of the two inbred lines generated considerable variations in the expression abundance of lncRNAs and protein-coding transcripts. In the co-expression networks responding to salt stress, some TFs were targeted by the lncRNAs, which further regulated the salt tolerance-related functional transcripts. We constructed a regulatory pathway of maize seedlings to salt stress, which was mediated by the hub lncRNA MSTRG.8888.1 and participated by the bHLH TF and its downstream target transcripts. Future work will be focused on the functional revelation of the regulatory pathway.

Identification of human gene research articles with wrongly identified nucleotide sequences

Nucleotide sequence reagents underpin molecular techniques that have been applied across hundreds of thousands of publications. We have previously reported wrongly identified nucleotide sequence reagents in human research publications and described a semi-automated screening tool Seek & Blastn to fact-check their claimed status. We applied Seek & Blastn to screen >11,700 publications across five literature corpora, including all original publications in Gene from 2007 to 2018 and all original open-access publications in Oncology Reports from 2014 to 2018. After manually checking Seek & Blastn outputs for >3,400 human research articles, we identified 712 articles across 78 journals that described at least one wrongly identified nucleotide sequence. Verifying the claimed identities of >13,700 sequences highlighted 1,535 wrongly identified sequences, most of which were claimed targeting reagents for the analysis of 365 human protein-coding genes and 120 non-coding RNAs. The 712 problematic articles have received >17,000 citations, including citations by human clinical trials. Given our estimate that approximately one-quarter of problematic articles may misinform the future development of human therapies, urgent measures are required to address unreliable gene research articles.

LncRNAs Are Differentially Expressed between Wildtype and Cell Line Strains of African Trypanosomes

Trypanosoma brucei is a parasitic protist that causes African sleeping sickness. The establishment of T. brucei cell lines has provided a significant advantage for the majority of T. brucei research. However, these cell lines were isolated and maintained in culture for decades, occasionally accumulating changes in gene expression. Since trypanosome strains have been maintained in culture for decades, it is possible that difference may have accumulated in fast-evolving non-coding RNAs between trypanosomes from the wild and those maintained extensively in cultures. To address this, we compared the lncRNA expression profile of trypanosomes maintained as cultured cell lines (CL) to those extracted from human patients, wildtype (WT). We identified lncRNAs from CL and WT from available transcriptomic data and demonstrate that CL and WT have unique sets of lncRNAs expressed. We further demonstrate that the unique and shared lncRNAs are differentially expressed between CL and WT parasites, and that these lncRNAs are more evenly up-regulated and down-regulated than protein-coding genes. We validated the expression of these lncRNAs using qPCR. Taken together, this study demonstrates that lncRNAs are differentially expressed between cell lines and wildtype T. brucei and provides evidence for potential evolution of lncRNAs, specifically in T. brucei maintained in culture.

Characterisation of the Complete Mitochondrial Genome of Critically Endangered Mustela lutreola (Carnivora: Mustelidae) and Its Phylogenetic and Conservation Implications

In this paper, a complete mitochondrial genome of the critically endangered European mink Mustela lutreola L., 1761 is reported. The mitogenome was 16,504 bp in length and encoded the typical 13 protein-coding genes, two ribosomal RNA genes and 22 transfer RNA genes, and harboured a putative control region. The A+T content of the entire genome was 60.06% (A > T > C > G), and the AT-skew and GC-skew were 0.093 and −0.308, respectively. The encoding-strand identity of genes and their order were consistent with a collinear gene order characteristic for vertebrate mitogenomes. The start codons of all protein-coding genes were the typical ATN. In eight cases, they were ended by complete stop codons, while five had incomplete termination codons (TA or T). All tRNAs had a typical cloverleaf secondary structure, except tRNASer(AGC) and tRNALys, which lacked the DHU stem and had reduced DHU loop, respectively. Both rRNAs were capable of folding into complex secondary structures, containing unmatched base pairs. Eighty-one single nucleotide variants (substitutions and indels) were identified. Comparative interspecies analyses confirmed the close phylogenetic relationship of the European mink to the so-called ferret group, clustering the European polecat, the steppe polecat and the black-footed ferret. The obtained results are expected to provide useful molecular data, informing and supporting effective conservation measures to save M. lutreola.

Complete Genome Sequence of Bacteriophage Fizzles, Isolated from Microbacterium foliorum

Microbacteriophage Fizzles has a 62,078-bp linear double-stranded DNA genome sequence, predicted to contain 104 protein-coding genes. Fizzles is a Siphoviridae actinobacteriophage isolated from an ant hill soil sample collected in Stephenville, TX. Microbacteriophage Fizzles has >83.6% nucleotide identity with microbacteriophages Squash and Nike.

Genomic Characterization and Annotation of Two Novel Bacteriophages Isolated from a Wastewater Treatment Plant in Qatar

We report the genome sequences of Escherichia phage C600M2 (length, 88,162 bp; G+C content, 38.98%) and Escherichia phage CL1 (length, 87,820 bp; G+C content, 41.32%), which were isolated from a wastewater treatment plant in Qatar. Both Escherichia phage C600M2 and Escherichia phage CL1 genomes contain 128 protein-coding genes and 26 tRNAs.

The complete mitochondrial genomes of Notiophilus quadripunctatus Dejean, 1826 and Omophron limbatum (Fabricius, 1777): New insights into the mitogenome phylogeny of the Carabidae (Insecta, Coleoptera)

The Carabidae is by far the largest family of the Adephaga, with more than 40,000 described species. Whereas their phylogeny has been extensively studied, convergences and reversals in morphological traits prevent a robust phylogenetic concept so far. In this study, we sequenced the complete mitochondrial genomes of Notiophilus quadripunctatus (Nebriinae) and Omophrom limbatum (Omophroninae) using high-throughput sequencing. Both mitogenomes consisted of a single circular DNA molecule that encoded the typical 13 protein-coding genes, two subunits of mitochondrial RNAs, 22 tRNAs and a putative control region. Our phylogenetic study placed Omophrom limbatum as sister taxon to all other analyzed ground beetle species whereas Notiophilus quadripunctatus was identified as sister to Nebria brevicollis as part of the Nebriinae. The analyses also support the monophyly of the Cicindelidae but place Trachypachus holmbergi (Trachypachidae) within the Carabidae. Nevertheless, almost all carabid subfamilies with more than one analyzed species were identified as monophyla.

Characterization, Comparison of Four New Mitogenomes of Centrotinae (Hemiptera: Membracidae) and Phylogenetic Implications Supports New Synonymy

To explore the phylogenetic relationships of the subfamily Centrotinae from the mitochondrial genome data, four complete mitogenomes (Anchon lineatus, Anchon yunnanensis, Gargara genistae and Tricentrus longivalvulatus) were sequenced and analyzed. All the newly sequenced mitogenomes contain 37 genes. Among the 13 protein-coding genes (PCGs) of the Centrotinae mitogenomes, a sliding window analysis and the ratio of Ka/Ks suggest that atp8 is a relatively fast evolving gene, while cox1 is the slowest. All PCGs start with ATN, except for nad5 (start with TTG), and stop with TAA or the incomplete stop codon T, except for nad2 and cytb (terminate with TAG). All tRNAs can fold into the typical cloverleaf secondary structure, except for trnS1, which lacks the dihydrouridine (DHU) arm. The BI and ML phylogenetic analyses of concatenated alignments of 13 mitochondrial PCGs among the major lineages produce a well-resolved framework. Phylogenetic analyses show that Membracoidea, Smiliinae and Centrotinae, together with tribes Centrotypini and Leptobelini are recovered as well-supported monophyletic groups. The tribe Gargarini (sensu Wallace et al.) and its monophyly are supported.