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PNAS Study Examines Effect of Age on Cell Division Rates, More

Cell division rates dwindle as people age, researchers led by Johns Hopkins University School of Medicine's Bert Vogelstein report in the Proceedings of the National Academy of Sciences this week. They collected tissue samples from the colon, duodenum, esophagus, and sinuses of 13 people between the ages of 20 and 29 and of 13 people between the ages of 80 and 89. Using the Ki67 antibody, a marker of proliferation, they found that the young adults had a higher portion of dividing cells, as compared to the older adults. This, the researchers say, could contribute to the drop off in cancer incidence seen among the elderly.

A University of California, Berkeley-led team uncovered different genetic lineages of the chytrid fungus Batrachochytrium dendrobatidis, a pathogen that infects amphibians. They swabbed amphibians' skin to collect fungal samples for sequencing, through which they found a divergent BD lineage within Southeast Asia. Further, they note that this lineage sometimes co-occurs with global panzootic lineage. Because of this, they argue that additional screening is needed, especially where these Bd lineages overlap.

The mutational changes wrought by exposure to UV light varies across chromatin states, a University of Gothenburg-led team reports in PNAS. They characterized mutations induced by UV radiation through the development of pyrimidine dimers, and, in particular, found that the usual UV trinucleotide signature is altered in promoters. There, they found reduced TCG > TTG transitions, which they attributed to promoter methylation status.