Introducing GEODES

In the McMahon Lab, we’ve always got something big planned. GEODES, which stands for “Gene Expression in Oligotrophic, Dystrophic, and Eutrophic Systems,” is this summer’s big sampling effort. This project stems from our earlier work on diel cycling in freshwater specifically looking at light-powered proteins called rhodopsins. The focus of GEODES is on microbially-mediated carbon cycling. We hypothesize that we will see trends in gene expression on the scale of a single day that are driven by carbon exchange between photosynthetic microbes and non-photosynthetic microbes. Check out our JGI Community Sequencing Program plan here!

We’re also expanding this project to include three lakes: Sparkling Lake and Trout Bog near Minocqua, WI, and Lake Mendota in Madison. These lakes have very different nutrient concentrations. Lake Mendota is a highly productive lake, with lots of nitrogen and phosphorus inputs from the surrounding agricultural land, resulting in large amounts of photosynthesis. Sparkling Lake has low nutrient levels, making its waters clear and, well, sparkling. It has much less microbial growth than Lake Mendota. Trout Bog is a bog lake, meaning it has very high carbon levels, but is low in other nutrients. Each of these lakes contains different types of photosynthetic microbes. While we expect that the carbon compounds exchanged between microbes in each lake will be different, we still expect to see daily trends that are similar in all three lakes. The results of this experiment will hopefully tell us more about how carbon is processed in different types of lakes, as well as help us identify reactions performed by specific bacterial groups.

From left to right: water from Trout Bog, Sparkling Lake, and Lake Mendota. Lake Mendota usually develops a greenish tint later in the summer.

A project of this size requires a lot of preparation. The sampling is scheduled for July, but in the meantime, we’re busy getting our field equipment set up, vehicles rented, deciding what metadata to collect, and much more. Stay tuned for updates on GEODES!

-Alex

This slideshow requires JavaScript.