Skip to main content
Premium Trial:

Request an Annual Quote

This Week in PNAS: Mar 3, 2015

In the Proceedings of the National Academy of Sciences, researchers from the US and Finland explore the role that amplifications of the oncogene Akt3 play in the progression of the brain cancer glioma. After detecting amplifications of Akt3, Akt2, and Akt1 in several cancer types — including the most common form of glioma, called glioblastoma — the researchers tracked glioma progression and gene expression profiles in mouse models of glioma that harbored various Akt isoforms. The transcriptional patterns present in the tumors pointed to marked ties between Akt3 amplification, tumor progression, and an expression signature associated with DNA repair pathway activity, prompting the study's authors to argue that Akt3 may offer a new target for staunching DNA repair-related treatment resistance.

University of California, Berkeley, mathematics researcher Kelley Harris describes apparent mutation rate differences detected in Europeans compared to other human populations. Using sequence data for almost 1,100 individuals tested through the 1000 Genomes Project, Harris found that individuals of European ancestry appear more prone to carry a sequence transition that has also been independently linked to melanoma, hinting that the rise in this form of variation might be related to enhanced UV light sensitivity in European populations. "Although it is not clear whether the excess mutations are harmful or directly related to the UV sensitivity of light skin," Harris writes, "this result demonstrates that the human mutation rate has evolved on a much faster timescale than previously believed."

Finally, an international team sequenced the genome of the Tibetan Plateau frog Nanorana parkeri in a bid to better understand amphibian genetics and the evolution of tetrapod animals. The researchers did de novo genome sequencing on DNA from a female N. parkeri frog collected on the Tibetan Plateau, along with transcriptome sequence on multiple Tibetan frog tissues. They then compared the resulting assembly — which covered 2 billion bases of the Tibetan frog's genome to around 83-fold average depth — to sequences for the distantly related frog Xenopus tropicalis and other sequenced vertebrates. The analysis revealed roughly 11 million bases of conserved elements and genes that appear to be shared across frog species, for instance, and pointed to relatively slow rates of structural change in the frog lineage.