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This Week in PNAS: Apr 2, 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, Columbia University's Harmen Bussemaker and colleagues from the US and the Netherlands looked at regulatory mechanisms related to mutagenic insertion of retroviruses — a process that can lead to tumor formation. The team used a combination of genotyping and gene expression data to assess 97 splenic tumors that had been induced in mice through retroviral-insertion mutagenesis. With that data, the researchers found expression signatures associated with shared insertion loci. Those signatures, in turn, helped in scrutinizing transcription factor, promoter, and other regulatory interactions contributing to tumorigenesis.

Using mutant yeast as a model system, a team from the US and Belgium has found evidence that reveals the role diminished 60S ribosomal subunit maturation levels play in diseases known as ribosomopathies, which can eventually lead to cancer development. Based on ribosomal mutations previously described in acute lymphoblastic T-cell leukemia, the researchers developed a system for studying the lack of cells that characterize early stages of ribosomopathy and the excessive cell growth that occurs later on once compensatory changes in ribosome production kick in.

Finally, American and Chinese researchers performed a phylogenetic analysis as part of their look at factors leading to an extinction event at the end of the Permian period more than 250 million years ago. That group brought together data on carbon isotope patterns, nickel deposit data, and methanogenic archaea phylogeny in sediments from South China to take a peek at end-Permian environmental conditions. Findings from the study suggest horizontal gene transfer involving methane-producing Methanosarcina archaea had a role in transforming the carbon cycle at that time, contributing to shifts in carbon dioxide and oxygen levels, spurred on by a boost in nickel availability due to volcanic eruptions.