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This Week in PNAS: Apr 21, 2015

A study appearing in the early, online edition of the Proceedings of the National Academy of Sciences this week describes microbial patterns detected in household dust samples from across the country. A team from the US and Denmark used 16S ribosomal RNA gene sequencing and internal transcribed spacer sequencing to identify bacteria and fungal phylotypes in volunteer-collected dust swabs from sites above external doors in some 1,200 American households. The results suggest geography helps shape airborne microbial communities, for example, with samples from the coasts sharing compositional features not found in other parts of the country. GenomeWeb has more on the study here.

A team from China and the US used genome sequencing to delve into the roots of desiccation tolerance in the Resurrection Plant, Boea hygrometrica. The researchers put together a draft genome assembly that spans some 1.5 billion bases and contains 49,374 predicted protein-coding genes, nearly 200 microRNA genes, and a raft of repeat sequences. Together with transcriptomes generated from B. hygrometrica leaves during dessication, the assembly made it possible to track down information on genome duplications in the plant's past and alternative splicing events that may contribute to its drought-survival features.

Researchers from Belgium, Peru, China, and the US present evidence for expression of Agrobacterium DNA in cultivated sweet potato plants — a pattern they attributed to naturally occurring transgenic events. The team saw the first sign of these transfer DNA, or T-DNA, fragments through an analysis of small interfering RNA sequences in the Huachano sweet potato landrace. Its subsequent experiments in that landrace, which used quantitative PCR and other approaches, unearthed two Agrobacterium T-DNAs that also turned up in searches done in hundreds of other cultivated sweet potato accessions. "Our finding, that sweet potato is naturally transgenic while being a widely and traditionally consumed food crop, could affect the current consumer distrust of the safety of transgenic food crops," the study's authors argue.