Skip to main content
Premium Trial:

Request an Annual Quote

This Week in PNAS: Nov 6, 2018

In the early, online version of the Proceedings of the National Academy of Sciences, researchers from Dartmouth College and the University of California, Riverside, explore drug resistance evolution in previously untreated Candida lusitaniae fungus during infection in a single individual with cystic fibrosis. Using whole-genome sequencing, drug sensitivity assays, and/or other approaches, the team assessed hundreds of C. lusitaniae isolates from different parts of the patient's lung over time following treatment with the antifungal fluconazole. The analysis pointed to at least a dozen resistance-related alleles in the resistance-related transcription factor-coding gene MRR1, along with other, heterogeneous resistance alleles.

A China Agricultural University-led team takes a look at epigenetic contributors to pregnancy success or failure in a pig model of mammalian cloning. The researchers used genome sequencing, bisulfite sequencing, and RNA sequencing to identify breed-specific variants, expression profiles, and parent-of-origin methylation in pig induced pluripotent stem cells and nuclear transfer embryos produced from reciprocal crosses between Duroc and Rongchang pig breeds. Their results suggest that epigenetic sources of post-implantation pregnancy failure may stem from aberrant silencing of imprinted genes, including a retrotransposon-derived gene called RTL1. The authors note that RTL1 "has broad fertility implications across mouse, rat, pig, cattle, and human from nuclear transfer cloning, tetraploid complementation, and artificial insemination, to natural fertilization."

Researchers in China and the US describe a point mutation in the cotton bollworm, Helicoverpa armigera, that appears to assist the pest persist in the presence of transgenic "Bt" cotton crops engineered to produce insecticidal proteins stemming from the Bacillus thuringiensis bacterial species. With a combination of genome-wide association analyses, genetic mapping, comparative genomics, and CRISPR-Cas9-based editing, the team tracked down a dominant, resistance-related cotton bollworm point mutation affecting the tetraspanin gene. In cotton bollworm moth samples from nearly two dozen field sites in northern China, the authors add, the frequency of the tetraspanin mutation appeared to rise dramatically over the decade between 2006 and 2016, prompting them to encourage proactive identification and tracking to help curb resistance.