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PNAS Papers on MERS Vaccine Strategy, Desert Plant Genomics, Spatial Transcriptomics

Editor's Note: Some of the articles described below are not yet available at the PNAS site but are scheduled to be posted this week.

A team from Spain describes a potential self-amplifying RNA replicon-based vaccine strategy for the virus behind Middle East respiratory syndrome. "We previously showed that the deletion of the envelope (E) gene from the Middle East respiratory syndrome coronavirus (MERS-CoV) produces a replication-competent propagation-defective RNA replicon (MERS-CoV-delta-E)," the researchers write. In their current experiments, they report, replicons containing both E gene deletions and in one of four accessory genes encoded by other viral open reading frames showed significant attenuation and replication defects in a mouse model of MERS-CoV infection, leading to sterilizing immunity in mice challenged with virulent forms of the virus. "The in vivo evaluation of these RNA replicons demonstrated that they were safe and stable vaccine candidates that induces potent sterilizing immunity," the authors suggest.

Investigators in China, the Czech Republic, and Israel present findings from a genomic analysis of desert-adapted psammophyte plants from two Pugionium species in the Brassicaceae family. Using a combination of long-read sequencing, short-read sequencing, chromosome conformation capture, RNA sequencing, comparative chromosome painting, and/or other approaches, the team put together and began analyzing genome assemblies for P. cornutum and P. dolabratum. In addition to uncovering some 31,412 and 30,614 predicted protein-coding genes in the two species, respectively, the authors saw signs that the shared ancestor of P. cornutum and P. dolabratum went through a whole-genome duplication event, while chromosomal rearrangements, gene evolution, and gene flow appear to have contributed to a more recent split between the species. "Our results provide insights into plant adaptation in the arid deserts," they write, "and highlight the significance of polyploidy-driven chromosomal structural variations in species divergence."

A Johns Hopkins University-led team outlines a spatial transcriptomics strategy known as SpatialTime, which it applied to a mouse model of mammalian skeleton formation. The researchers focused on the process of cranial suture closure in a region on top of the skull called the calvaria, using cell and differentiation assays, in vivo SpatialTime transcriptomic profiling, and other approaches to demonstrate that sensory nerve signaling contributes to this cranial bone formation process in mice. "Here, we validate a spatial transcriptomics platform, which allowed us to map changes in the molecular landscape across the developing cranium of mice in which sensory nerve innervation is genetically blocked," they write, noting that "sensory, nerve-derived signals, including follistatin-like 1, coordinate cranial bone patterning by regulating the proliferation and differentiation of bone precursor cells within the suture mesenchyme."