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This Week in PNAS: Sep 3, 2014

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.

In the early, online edition of the Proceedings of the National Academy of Sciences, investigators from China, Australia, Japan, and Israel describe the mosaic ancestral sequences they detected through transcriptome sequencing of wild and domesticated barley. Through RNA sequencing on tissue samples from a dozen wild barley seedlings (Hordeum spontaneum) and seedlings representing nine genotypes of the cultivated barley H. vulgare, the team found tens of thousands of transcripts that proved useful in its subsequent look at population structure and barley origins. From the transcript patterns detected, the study's authors suggest that cultivated barley carries sequences from ancestral plants in both the Near East and Tibet, perhaps reflecting parallel domestication in each region.

Massachusetts Institute of Technology researchers used single cell sequencing to examine the extent to which aneuploidy occurs in mouse and human tissues. With sequences from individual cells isolated from mouse and human skin, liver, and brain tissues, the team profiled copy number patterns as a means of assessing aneuploidy in these samples. Overall, the study's authors saw only rare examples of aneuploidy in the tissues tested, prompting them to conclude that somatic copy number changes probably do not have positive functional roles in non-cancerous mammalian cells.

Finally, a team from the US and Japan describes the reverse genetics system it developed for studying the gastroenteritis-causing human norovirus, which has proven impervious to culturing in the lab. By placing the human norovius genome sequence behind a mammalian promoter in a plasmid, the researchers say, they were able to produce a system that could perform norovirus-like elongation, replication, and particle formation in mammalian cells without an accompanying helper virus. Moreover, they note, adding a green fluorescent protein tag to such a system made it possible to follow human or animal norovirus particle formation.