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This Week in PNAS: Mar 29, 2016

In the early, online edition of the Proceedings of the National Academy of Sciences, Stanford University's Stephen Quake and colleagues describe a single-molecule imaging method they developed to assess two epigenetic modifications — 5-methylcytosine and 5-hydroxymethylcytosine — simultaneously and in relation to one another. The team used the imaging assay method, which relies on selective, dual chemical labeling of 5mC and 5hmC using different fluorophores, to profile the epigenetic marks in mouse tissues. And with the help of single-molecule fluorescence resonance energy transfer experiments, the investigators demonstrate that they could discern the distance between 5mC and 5hmC modifications, both in synthetic DNA, DNA from the mouse cerebellum, and so on.

Japanese researchers track blood metabolite levels in individuals from different age groups for another PNAS paper. The team used high-resolution liquid chromatography-mass spectrometry to analyze metabolites in 126 blood samples from 15 young volunteers who were 29-years-old, on average, and 15 elderly individuals who were around 81-years-old. The search led to more than a dozen blood metabolites with age-related patterns in the blood, including six age-related compounds related to red blood cell metabolism, physical activity, and liver and kidney function.

Finally, an international team presents findings from an analysis of Y chromosome evolution in the malaria parasite-carrying mosquito species Anopheles gambiae. Using multiple Y chromosome sequencing strategies, together with RNA sequencing on various mosquito tissues and developmental stages, the researchers got a look at the sequences and structure of the An. gambiae Y chromosome. Their results point to extensive tandem array repeat content in the mosquito Y chromosome, coupled with a small set of core, Y-linked genes. "These genes and repeats evolve rapidly," they write, "bringing about remodeling of the Y, even among closely related species."