MilliporeSigma

Microbial DNA records historical delivery of anthropogenic mercury.

The ISME journal (2015-06-10)
Alexandre J Poulain, Stéphane Aris-Brosou, Jules M Blais, Michelle Brazeau, Wendel Bill Keller, Andrew M Paterson
ABSTRACT

Mercury (Hg) is an anthropogenic pollutant that is toxic to wildlife and humans, but the response of remote ecosystems to globally distributed Hg is elusive. Here, we use DNA extracted from a dated sediment core to infer the response of microbes to historical Hg delivery. We observe a significant association between the mercuric reductase gene (merA) phylogeny and the timing of Hg deposition. Using relaxed molecular clock models, we show a significant increase in the scaled effective population size of the merA gene beginning ~200 years ago, coinciding with the Industrial Revolution and a coincident strong signal for positive selection acting on residues in the terminal region of the mercuric reductase. This rapid evolutionary response of microbes to changes in the delivery of anthropogenic Hg indicates that microbial genomes record ecosystem response to pollutant deposition in remote regions.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Mercury, ≥99.99% trace metals basis
Sigma-Aldrich
Mercury, ACS reagent, 99.9995% trace metals basis
Sigma-Aldrich
Mercury, electronic grade, 99.9999% trace metals basis