Editor's Note: The articles described below are not yet available at the PNAS site, but they are scheduled to be posted some time this week.
In the early, online edition of the Proceedings of the National Academy of Sciences, a team from the UK and Switzerland report on an apparent mechanistic role for a locus linked to sporadic forms of Parkinson disease through past genome-wide association studies. Using an RNA interference screen, the researchers searched for genes involved in mitochondrial degradation, or mitophagy — a process previously attributed to the autosomal recessive Parkinson risk genes called PINK1 and parkin. Among the sites identified was a Parkinson disease-associated locus containing the sterol regulatory binding protein-related gene SREBF1, which appears to have a previously unappreciated role in regulating mitophagy.
The microbes comprising communities found in the intestines of wild mice appear to be intimately linked to dietary factors, according to another PNAS study. Researchers from Germany and the US used a combination of 16S ribosomal gene sequencing and metagenomic sequencing to look at the microbial community members and microbial gene sets present in the guts of wild mice samples from sites across Western Europe. Along with isotope-based assessments of the animals' diet, comparisons with lab mice, and transplants of some wild mice into the lab, the sequencing data revealed two main microbial enterotypes coinciding with diets predominated by either plant or animal-derived material.
Researchers from the Universities of Geneva and Cambridge explored genetic mechanisms that protect Arabidopsis plants from persistent epigenetic changes associated with abiotic stress. With the help of a modified Arabidopsis line carrying a heat stress activated luciferase gene and another mutation meant to enhance this effect, the team performed a mutagenesis screen aimed at finding genes that diminish stress-related dips in gene silencing by epigenetic factors. The search suggested that the chromatin regulatory genes DDM1 and MOM1 could reset some stress-associated epigenetic effects in the plants, thwarting transmission of gene silencing loss at certain genomic sites to the next generation.