Western University BiologyWestern Science

Norman Hüner, PhD

Life at the Edge: Photosynthetic Adaptation and Phenotypic Plasticity in Extreme Environments


Norman Huner Position:

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Professor
Canada Research Chair
North Campus Building 301J
(519) 661-2111 x 86488
519 661-3935
nhuner@uwo.ca
http://www.uwo.ca/biology/faculty/huner/

Surprising to most, the Earth is generally a cold place. Eighty per cent of our biosphere is permanently below 5°C, including most of the oceans and the polar and alpine regions. Antarctica and its surrounding oceans as well as the Arctic, once assumed to be devoid of biodiversity has been shown to be teeming with diverse life forms. Consequently, these organisms represent some of the least studied but are crucial components to one of the most important ecosystems on the planet. Eukaryotic algae and cyanobacteria are the dominant life forms in these cold habitats, many of which are psychrophiles, that is, obligately adapted to low temperature but die at “normal” temperatures. The Antarctic green alga, Chlamydomonas sp. UWO 241 is the primary biological system under study in my laboratory and has become a model system for study of life at the edge.

A photoautotrophic life style requires the integration of photophysical, photochemical and biochemical processes involved in the conversion of light energy into stable storage forms of carbon for growth and metabolism. The photophysical processes of light absorption and energy trapping (energy source) occur on a 10-12 to 10-6s time scale and are temperature insensitive. In contrast, biochemical reactions involved energy conversion and storage (energy sink) are temperature sensitive and occur on time scale that is 10 orders of magnitude slower. These disparate rates can expose photoautotrophs to excess excitation energy (EEE) which result in a potential cellular energy imbalance measured as excitation pressure. Consequently, an essential component in the evolution of photoautotrophic psychrophiles must be the maintenance of cellular energy balance between source and sink.

The long-term goal of my research programme is the complete physiological, biochemical and molecular characterization of Chlamydomonas sp. UWO 241 with respect to the structure and function of its novel photosynthetic apparatus in order to explain how UWO 241 maintains cellular energy balance under its unique and extreme environment as well as to elucidate the molecular basis of psychrophily. This is accomplished by combining physiological, biochemical, biophysical and molecular techniques and approaches.

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