Editor's Note: Some of the articles described below are not yet available at the PNAS site, but they are scheduled to be posted some time this week.
Researchers at the University of California, Berkeley, the Lawrence Livermore National Laboratory, and elsewhere present findings from a metatranscriptomic analyses of RNA viruses in soil samples from four distinct habitats tested over time around a potted wild oat plant. Using RNA sequence profiles for 48 soil samples collected across the span of 22 days from rhizosphere, detritosphere, rhizosphere plus root, and unamended soil sites, the team identified diverse RNA virus sequences in the soil and sequences stemming from apparent viral hosts such as fungi or Proteobacteria, along with their dynamics and potential contributions to the broader carbon cycle. "These results greatly expand the known diversity of viruses and contribute to understanding microbial interactions in soil with major implications in carbon cycling," the authors report.
A team from the US and Germany describe apparent ties between memory impairment and a group of retrotransposons known as endogenous retroviruses, which were previously implicated in cognitive decline in Drosophila fruit flies. To explore a potential role for endogenous retroviruses in mammals, the researchers in two mouse models, relying on RNA sequencing, PCR, immunohistochemistry, and other molecular and behavioral assays to narrow in on a rise in ERV activity in the hippocampus in mice with memory impairments related to the same brain region. Based on these and other findings, the authors suggest that "chronic [endogenous retrovirus] activation is associated with cognitive impairment, measured with hippocampus-related tasks, in mouse models."
Princeton University and Simons Foundation researchers report on an improved, "photoswitchable" form of MEK1, a gene that codes for an enzyme that activates the ERK signaling pathway. After demonstrating that an earlier version of photoswitchable MEK1 (psMEK) had sub-par functionality in vivo in Drosophila fruit fly embryos expressing psMEK compared with wild type versions of the gene, the team came up with a gain-of-function, destabilizing mutation-based approach to boost the activity of photoswitch-activated MEK in vitro and in Drosophila and zebrafish models. "Our approach for optimizing and tuning light-activated protein kinases is not limited to MEK," the authors note, "and can be used to systematically extend the capabilities of light-activated regulatory enzymes.