Aquatic Sciences Meeting, Albuquerque 2001

CS41 Phytoplankton: Nutrient Dynamics and Physiology

Date: Friday, February 16, 2001, Time: 10:15:00 AM

Location: Galisteo

Hildebrand, M, , Scripps Institution of Oceanography, Univ. of California, San Diego, La Jolla, CA, USA, mhildebrand@ucsd.edu

CLONING AND CHARACTERIZATION OF mRNA LEVELS OF DIATOM NITRATE AND AMMONIUM TRANSPORTERS

A long-standing observation in phytoplankton ecology is the preferential use of ammonium over nitrate as a nitrogen source, yet the underlying molecular mechanisms for this phenomenon are not understood. We have cloned the first nitrate (Hildebrand and Dahlin, 2000, J. Phycol. 36:702) and ammonium (unpublished data) transporter genes in a marine organism, from the diatom Cylindrotheca fusiformis. The genes are well conserved with homologs in other organisms. Specific probes were used to monitor mRNA levels during growth in different nitrogen sources, and changes in levels resulting from a switch in nitrogen source. The data indicate specific induction or repression of mRNA levels in response to nitrogen source, and a very rapid change in levels when sources are switched. Control of expression of nitrate and ammonium transporter genes is therefore likely to play a significant role in the utilization of different nitrogen sources by diatoms, and perhaps other phytoplankton.

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Aquatic Sciences Meeting, Albuquerque 2001

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