EAGER: Gene expression patterns in high C02-adapted Trichodesmium

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The potential for biogeochemically-critical marine organisms, such as the N2-fixing cyanobacterium Trichodesmium, to adapt to a rapidly changing environment is a poorly understood but key determinant of future ocean food webs and elemental cycles. Despite an exponential increase in the sophistication of molecular tools available to the ocean science community, no study has yet applied these methods to relevant marine organisms in conjunction with microbial evolution experiments such as those pioneered by R.E. Lenski and colleagues for the model enteric bacterium Escherichia coli.Intellectual Merit:In this EAGER project, the PIs will conduct an exploratory approach that uses tiled microarray methods to evaluate changes in the expression of both coding and non-coding regions of the genome in Trichodesmium cultures that have been maintained in long-term (3 years) high CO2 adaptation experiments. The objective of this work is to demonstrate that a novel combination of evolutionary experimental techniques and state-of-the-art gene expression methods can be used to yield unique insights into adaptive changes in keystone marine micro-organisms such as Trichodesmium in response to selection by environmental change variables. The over-arching goal is to increase our mechanistic understanding of the ways that evolution could shape the responses of marine biota to future changes in ocean chemistry and climate.Broader Impacts:This project will help support and train a new USC Ph.D. student, and research activities will include USC undergraduate biology majors. Public education and communication efforts for this project will be greatly enhanced by an annual series of public outreach and professional colloquia sponsored by a USC-funded "2020" initiative to integrate scientific and societal responses to climate change in the Southern California region. Any evolution-driven shifts in the growth and N2 fixation patterns of Trichodesmium, a keystone oceanic functional group, have large consequences for marine ecology, carbon cycling, and the food chains that support important living resources. The biggest scientific impact of this EAGER project could be to offer verification of a pioneering new approach to help determine how the microbes that are fundamental to today's ocean biogeochemical cycles will adapt to anticipated and unprecedented rates of change in marine ecosystems.