PARENT SESSION
Posters P4C Controling CO₂: Stomates and carbon concentrating mechanisms. Abstracts (631-642)

A possible role of a small protein with similarity to conserved bacterial proteins in the growth of Chlamydomonas reinhardtii under low CO₂ conditions. Ruby Ynalvez^*,1, Lacey Howard¹, James Moroney¹, ¹ Department of Biological Sciences, Baton Rouge, LA, USA

ABSTRACT- Chlamydomonas reinhardtii is a unicellular eukaryotic alga which possesses a CO₂ concentrating mechanism (CCM) that enables it to grow at low CO₂ concentrations. To study this mechanism and identify genes required for growth in a low CO₂ environment, insertional mutants have been generated utilizing the Ble^R gene which encodes a protein that confers resistance to the antibiotic, Zeocin. Transformants resistant to Zeocin and colonies that were Sick on Low CO₂ (SLC) were retained for further study. These SLC mutants may have a CCM gene or gene required for growth on low CO₂ disrupted by the insert. One of the insertional mutants that grew poorly on low CO₂ was slc 211. Genetic analysis indicated that the Ble^R was linked to the SLC phenotype. Genomic sequence flanking the insert was obtained using i-PCR. Sequence analysis showed homology to conserved bacterial proteins of unknown function, but there were no ESTs in this region of the genome. However, the presence of a gene was established by PCR and RLM-RACE. The gene disrupted in slc 211 was found to have 4 exons and the Ble^R was in the fourth exon. Complementation analyses were done using the wild type gene linked to a paromomycin resistant gene. Possible rescued mutants were obtained and the physiological and molecular characterization of these transformants will be done in order to further establish whether the gene disrupted in slc 211 is a gene required for growth on low CO₂ conditions. Supported by the National Science Foundation

KEY WORDS: CO₂ Concentrating Mechanism, Chlamydomonas reinhardtii, insertional mutants, low CO₂ conditions