Transposable element landscapes illuminate past evolutionary events in the endangered fern Vandenboschia speciosa

Vandenboschia speciosa is an endangered tetraploid fern species with a large genome (10.5 Gb). Its geographical distribution is characterized by disjoined tertiary flora refuges, with relict populations that survived past climate crises. Here we analyze the transposable elements (TEs) and found that they comprise about 76% of the V. speciosa genome, thus being the most abundant kind of DNA sequences in this gigantic genome. V. speciosa genome is composed of 51% and 5.6% of Class I and Class II elements, respectively. LTR retrotransposons were the most abundant TEs in this species (at least 42% of the genome), followed by non-LTR retrotransposons that constituted at least 8.7% of the genome of this species. We introduce an additional analysis to identify the nature of non-annotated elements (19% of the genome). A BLAST search of the non-annotated contigs against the V. speciosa TE database allowed determining the identity of almost half of them, which were most likely diverged sequence variants of the annotated TEs. In general, TE composition in V. speciosa resembles TE composition in seed plants. In addition, repeat landscapes revealed three episodes of amplification for all TEs, most likely due to demographic changes associated to past climate crises.

A Combinatorial Approach of High-Throughput Genomics and Mass Proteomics for Understanding the Regulation and Expression of Secondary Metabolite Production in Actinobacteria

Secondary metabolites produced by Actinobacteria are an important source of antibiotics, drugs, and antimicrobial peptides. However, the large genome size of actinobacteria with high gene coding density makes it difficult to understand the complex regulation of biosynthesis of such critically and economically important products.

Bacteriophages of Thermophilic ‘Bacillus Group’ Bacteria—A Review

Bacteriophages of thermophiles are of increasing interest owing to their important roles in many biogeochemical, ecological processes and in biotechnology applications, including emerging bionanotechnology. However, due to lack of in-depth investigation, they are underrepresented in the known prokaryotic virosphere. Therefore, there is a considerable potential for the discovery of novel bacteriophage-host systems in various environments: marine and terrestrial hot springs, compost piles, soil, industrial hot waters, among others. This review aims at providing a reference compendium of thermophages characterized thus far, which infect the species of thermophilic ‘Bacillus group’ bacteria, mostly from Geobacillus sp. We have listed 56 thermophages, out of which the majority belong to the Siphoviridae family, others belong to the Myoviridae and Podoviridae families and, apparently, a few belong to the Sphaerolipoviridae, Tectiviridae or Corticoviridae families. All of their genomes are composed of dsDNA, either linear, circular or circularly permuted. Fourteen genomes have been sequenced; their sizes vary greatly from 35,055 bp to an exceptionally large genome of 160,590 bp. We have also included our unpublished data on TP-84, which infects Geobacillus stearothermophilus (G. stearothermophilus). Since the TP-84 genome sequence shows essentially no similarity to any previously characterized bacteriophage, we have defined TP-84 as a new species in the newly proposed genus Tp84virus within the Siphoviridae family. The information summary presented here may be helpful in comparative deciphering of the molecular basis of the thermophages’ biology, biotechnology and in analyzing the environmental aspects of the thermophages’ effect on the thermophile community.

Illuminating the transposon insertion landscape in plants using Cas9-targeted Nanopore sequencing and a novel pipeline

Transposable elements (TEs), which occupy significant portions of most plant genomes, are a major source of genomic novelty, contributing to plant adaptation, speciation and new cultivar production. The often large, complex genomes of plants make identifying TE insertions from short reads challenging, while whole-genome sequencing remains expensive. To expand the toolbox for TE identification in plants, we used the recently developed Cas9-targeted Nanopore sequencing (CANS) approach. Additionally, as no current bioinformatics tools automatically detect TE insertions after CANS, we developed NanoCasTE, a novel pipeline for target TE insertion discovery. We performed CANS of three copies of EVD retrotransposons in wild-type Arabidopsis thaliana and obtained up to 40x coverage of the targets after only a few hours of sequencing on a MinION sequencer. To estimate the ability to detect new TE insertions, we exploited the A. thaliana ddm1 mutant, which has elevated TE activity. Using CANS, we detected 84% of these insertions in ddm1 after generating only 4420 Nanopore reads (0.2x genome coverage), and also unambiguously identified their locations, demonstrating the method's sensitivity. CANS of pooled (~50 plants) ddm1 plants captured >800 EVD insertions, especially in centromeric regions. CANS also identified insertions of a Ty3/Gypsy retrotransposon in the genomes of two Aegilops tauschii plants, a species with a large genome.

Exploring Antibiotic Susceptibility, Resistome and Mobilome Structure of Planctomycetes from Gemmataceae Family

The family Gemmataceae accomodates aerobic, chemoorganotrophic planctomycetes with large genome sizes, is mostly distributed in freshwater and terrestrial environments. However, these bacteria have recently also been found in locations relevant to human health. Since the antimicrobial resistance genes (AMR) from environmental resistome have the potential to be transferred to pathogens, it is essential to explore the resistant capabilities of environmental bacteria. In this study, the reconstruction of in silico resistome was performed for all nine available gemmata genomes. Furthermore, the genome of the newly isolated yet-undescribed strain G18 was sequenced and added to all analyses steps. Selected genomes were screened for the presence of mobile genetic elements. The flanking location of mobilizable genomic milieu around the AMR genes was of particular interest since such colocalization may appear to promote the horizontal gene transfer (HGT) events. Moreover the antibiotic susceptibility profile of six phylogenetically distinct strains of Gemmataceae planctomycetes was determined.

Genetic Markers of Genome Rearrangements in Helicobacter pylori

Helicobacter pylori exhibits a diverse genomic structure with high mutation and recombination rates. Various genetic elements function as drivers of this genomic diversity including genome rearrangements. Identifying the association of these elements with rearrangements can pave the way to understand its genome evolution. We analyzed the order of orthologous genes among 72 publicly available complete genomes to identify large genome rearrangements, and rearrangement breakpoints were compared with the positions of insertion sequences, genomic islands, and restriction modification genes. Comparison of the shared inversions revealed the conserved genomic elements across strains from different geographical locations. Some were region-specific and others were global, indicating that highly shared rearrangements and their markers were more ancestral than strain—or region—specific ones. The locations of genomic islands were an important factor for the occurrence of the rearrangements. Comparative genomics helps to evaluate the conservation of various elements contributing to the diversity across genomes.

Coronavirus-Replikation: Mechanismus und Inhibition durch Remdesivir

Coronaviruses use an RNA-dependent RNA polymerase to replicate and transcribe their RNA genome. The structure of the SARS-CoV-2 polymerase was determined by cryo-electron microscopy within a short time in spring 2020. The structure explains how the viral enzyme synthesizes RNA and how it replicates the exceptionally large genome in a processive manner. The most recent structure-function studies further reveal the mechanism of polymerase inhibition by remdesivir, an approved drug for the treatment of COVID-19.

Emerging therapeutic approaches to COVID-19

: Coronavirus diseases (COVID-19) is caused by a novel severe acute respiratory syndrome coronavirus (SARS-CoV-2), which is a positive single-stranded RNA virus having a large genome ~30 kb. SARS-CoV-2 is zoonotic and highly contagious, causing severe pneumonia-like symptoms. The efficacy of the different potential drug and drug candidates against COVID-19 has been investigated which are under various stages of clinical trials. The drugs effective against SARS, and Middle east respiratory syndrome (MERS), have been proposed to have a high potential for the treatment of COVID-19. Here, we selected plant-based materials implicated in the prevention and therapy of COVID-19. The vaccine has shown impressive results in producing antibodies against SARS-CoV2 and has been evaluated for safety, tolerance, and preliminary immunogenicity. Similarly, DNA/RNA-based therapy shown high clinical significance. The plant produces secondary metabolites in response to viral infection to protect them. Many nanomaterials produced by carbohydrates and lipids been exploited for their in-vitro and in-vivo delivery of antiviral therapeutics. Different classes of secondary metabolites have a different mechanism to counter virus attacks. While some natural medicines in the form of vitamins, minerals, herbs, and other nutrients help to enhance immunity, such measures should not replace social distancing, quarantining special care to protect from COVID-19. The standards of reporting were in accordance with the PRISMA guidelines.

Colorectal Cancer Risk by Genetic Variants in Populations With and Without Colonoscopy History

Background Polygenic risk scores (PRS), which are derived from results of large genome-wide association studies, are increasingly propagated for colorectal cancer (CRC) risk stratification. The majority of studies included in the large genome-wide association studies consortia were conducted in the United States and Germany, where colonoscopy with detection and removal of polyps has been widely practiced over the last decades. We aimed to assess if and to what extent the history of colonoscopy with polypectomy may alter metrics of the predictive ability of PRS for CRC risk. Methods A PRS based on 140 single nucleotide polymorphisms was compared between 4939 CRC patients and 3797 control persons of the Darmkrebs: Chancen der Verhütung durch Screening (DACHS) study, a population-based case-control study conducted in Germany. Risk discrimination was quantified according to the history of colonoscopy and polypectomy by areas under the curves (AUCs) and their 95% confidence intervals (CIs). All statistical tests were 2-sided. Results AUCs and 95% CIs were higher among subjects without previous colonoscopy (AUC = 0.622, 95% CI = 0.606 to 0.639) than among those with previous colonoscopy and polypectomy (AUC = 0.568, 95% CI = 0.536 to 0.601; difference [Δ AUC] = 0.054, P = .004). Such differences were consistently seen in sex-specific groups (women: Δ AUC = 0.073, P = .02; men: Δ AUC = 0.046, P = .048) and age-specific groups (younger than 70 years: Δ AUC = 0.052, P = .07; 70 years or older: Δ AUC = 0.049, P = .045). Conclusions Predictive performance of PRS may be underestimated in populations with widespread use of colonoscopy. Future studies using PRS to develop CRC prediction models should carefully consider colonoscopy history to provide more accurate estimates.