Single-celled Microbes in Polar Ice: A Proxy for Evolution over 100 Million Generations

Although glacial ice is the purest naturally occurring solid on Earth, it does contain dust particles and micron-size bacterial cells transported by winds from desert soils and oceans. Glacial ice contains a network of liquid veins within which microbes live, metabolize, and die, but do not grow. Using scanning fluorescence spectrometry, fluorescence microscopy, and flow cytometry, we have mapped the distribution and concentration of picocyanobacteria – cells less than 1 micron in size that contain chlorophyll and other naturally fluorescing pigments. They account for half of the photosynthetic biomass in the oceans, half of the primary production, and half of the oxygen in our atmosphere. Theire presence in ice at all depths in both Greenland and Antarctica provides an opportunity to study microbial evolution over about 100 million generations, using recent improvements in sensitivity to analyze the DNA of the cyanobacteria that are trapped in the ice.

Speaker: Buford Price, UC Berkeley

Room 105