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This Week in PNAS: Mar 6, 2012

In a paper appearing in this week's Early Edition, researchers at Johns Hopkins University School of Medicine and at the University of California, Irvine, show that deletion of Lhx2 in aging mice induces constitutive reactive gliosis, which then reduces "rates of ongoing apoptosis and compromised both rod and cone photoreceptor function." The Hopkins-Irvine team adds that these animals also "showed a dramatically reduced ability to induce expression of secreted neuroprotective factors and displayed enhanced rates of apoptosis in light-damage assays." Overall, the researchers say their study provides "in vivo evidence that Lhx2 actively maintains mature Müller glia in a nonreactive state, with loss of function initiating a specific program of nonproliferative hypertrophic gliosis."

Elsewhere in the Early Edition, an international team led by investigators in Italy presents sequence data that it says "clearly indicate a Mesoamerican origin of the common bean." The team says it set out to "solve the ongoing debate on the origins of the common bean by investigating the nucleotide diversity at five gene loci of a large sample that represents the entire geographical distribution of the wild forms of this species," and found evidence that supports "the occurrence of a bottleneck during the formation of the Andean gene pool that predates the domestication, which was suggested by recent studies based on multilocus molecular markers."

In another paper published online in advance this week, the University of Oxford's Bernadette Young and her colleagues use whole-genome sequencing data to report on the "evolutionary dynamics of Staphylococcus aureus during progression from carriage to disease."

Finally, an international team led by investigators in Israel this week reports a theoretical approach toward the identification of patterns in gene expression, through which they found that "biological systems similarly are comprised of a relatively unchanging hardware-like gene pattern," across organisms. "Orthogonal patterns of software-like transcripts vary greatly, even among tumors of the same type from different individuals," the authors write in PNAS. "Two distinguishable classes could be identified within the hardware-like component: those transcripts that are highly expressed and stable and an adaptable subset with lower expression that respond to external stimuli," they add.