Volume 4 Issue 7, July 2019

Microscopy and genomic analyses reveal an intriguing symbiosis between eukaryotic protists and Deltaproteobacteria in anoxic marine sediments that involves division of labour and interspecies hydrogen transfer, and enables collective magnetotactic motility by the consortium.

Eukaryotes evolved from a symbiosis involving Alphaproteobacteria and archaea phylogenetically nested within the Asgard clade. Two recent studies explore the metabolic capabilities of Asgard lineages, supporting refined symbiotic metabolic interactions that might have operated at the dawn of eukaryogenesis.

The rapidly dividing bacterium Vibrio natriegens holds promise for transforming traditional molecular biology and biotechnology processes. New work demonstrates that CRISPR interference technology is a robust tool for rapid, genome-wide screens in V. natriegens, facilitating future bioengineering efforts.

Biofilms are communities of bacteria that accumulate on surfaces such as replacement joints or intravenous catheters. By silencing a key communication system, Staphylococcus aureus builds tightly packed biofilms that can withstand attack by host immune cells.

This Review describes recent findings on the biogenesis and the role of defective viral genomes during replication of RNA viruses and discusses their impact on viral dynamics and evolution.

Here, the authors identify a mutualistic symbiosis between a non-motile, magnetic deltaproteobacterium and a protist, resulting in eukaryotic magnetoreception in marine anoxic sediments.

Using a short-hairpin RNA-based depletion strategy coupled with high throughput RNA sequencing, the authors unravel a layer of intrinsic immunity to positive-strand RNA viruses in immortalized hepatocytes that relies on basal expression levels of interferon regulatory factor 1 maintaining the transcription of a suite of antiviral genes.

A genome-wide CRISPR interference screen of the fast-growing Vibrio natriegens bacterium elucidates the make-up of minimal genomes and the metabolic pathways enabling rapid bacterial replication.

Staphylococcus aureus quorum sensing-deficient mutants form compact biofilms during infection that resist attack by phagocytes and confer enhanced immune evasion.

This study highlights the impact of the gut virome on host immunity by showing that a specific strain of murine astrovirus in the gut of immunodeficient mice protects them against norovirus and rotavirus infections, and that this protection depends on interferon-λ signalling in gut epithelial cells.

A comparative analysis of Asgard archaea genomes elucidates their metabolic potential and leads to the proposal of a revised ‘aerobic protoeukaryotes’ model for the origin of the eukaryotic cell.

Comparative genome and phylogenetic analyses of Asgard archaea reveal their metabolic potential and lead to the proposal of a revised model for eukaryogenesis, termed the reverse flow model.

Here, the authors characterize the symbiotic relationship between Haliclona sponges and its intracellular symbiont. The symbiont has a highly streamlined genome, yet retains a plasmid with the biosynthetic gene cluster for production of the defence chemical renieramycin and lives within chemobacteriocytes for nutrient acquisition.

A nonlinear time-series analysis was used to identify antibiotic use thresholds that are associated with the emergence of antibiotic resistance.

A combination of electron cryotomography and immunofluorescence microscopy reveals the structure of the core transmembrane subcomplex of the Legionella defective in organelle trafficking (Dot)/intracellular multiplication (Icm) type IVB secretion system (T4BSS) and an early-stage assembly process by which T4BSS components are targeted to the bacterial poles by DotU and IcmF.

Global sampling of microbial communities associated with wastewater treatment plants and application of ecological theory revealed a small, core bacterial community associated with performance and provides insights into the community dynamics in this environment.

Human DNase I is shown to be overexpressed in hypoxic environments in vitro and to be incorporated into human hepatitis B virus (HBV) particles, resulting in virions devoid of genomic DNA. These findings might help explain the low levels of circulating HBV DNA commonly observed in cirrhotic livers and liver tumours.

Following export from the parasite, the dense granule-resident effector TEEGR travels to the host cell nucleus where it interferes with host transcription factors to modulate immune signalling and regulate Toxoplasma persistence.

The study of the impact of mutations in the glutamate dehydrogenase enzyme from Bacillus subtilis across multiple settings, including liquid cultures, biofilms and in soil, highlights how bacterial growth states and the environment can differentially impact protein evolution.

The isolation and characterization of glycoprotein-specific monoclonal antibodies from a patient with Rift Valley fever (RVF) provide insights into the humoral immune responses elicited by the RVF virus as well as the therapeutic potential of antibody-based strategies.