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This Week in PNAS: May 9, 2017

In the early, online edition of the Proceedings of the National Academy of Sciences, researchers from the University of California and the Lawrence Berkeley National Laboratory outline insights gleaned from a new genome assembly for the green algae Chromochloris zofingiensis, a proposed feedstock for biofuel production. Using long and short sequencing reads, coupled with optical mapping assembly, the team put together a chromosome-level genome assembly for C. zofingiensis that housed nearly 15,300 predicted protein-coding genes — an annotation helped along with RNA sequencing-based transcriptomic profiles for the algae. From these data, the authors examined genes involved in producing a proposed nutraceutical called astaxanthin and explored the organism's relationships to other members of the green algae lineage.

An international team led by investigators in Germany and Austria explore the population history of the model plant Arabidopsis thaliana, using genome sequences for 78 present-day or herbarium samples collected in Africa. When they considered the genomes alongside available sequences for more than 1,100 Arabidopsis plant from Eurasia, the researchers detected high genetic diversity and deep evolutionary roots for A. thaliana representatives in Africa, where the plant appears to have originated and evolved self-pollination. The authors argue that the "previously unexplored reservoir of variation is remarkable given the large number of genomic studies conducted previously in this well-studied species and implies that assaying variation in Africa may often be necessary for understanding population history in diverse species."

Australian researchers report on altered gene interactions that appear to prompt solid tumor transformation. Using phylogenetic clues for more than 17,300 human genes, gene age patterns, and RNA sequencing information from seven solid tumor types assessed for the Cancer Genome Atlas, the team compared potential cancer contributions of genes conserved with unicellular organisms with those in multicellular creatures. Based on their results, the authors suggest "altered activity of genes at the interfaces between multicellular and unicellular regions of human gene regulatory networks activate primitive transcriptional programs, driving common hallmark features of cancer," suggesting that tweaks to biological systems with distinct evolutionary trajectories "may thus present powerful and broadly applicable treatment strategies for cancer."