Gene Expression in Two Cyanobacteria, Freshwater Synechococcus sp. PCC 7942 and Oceanic Synechococcus sp. WH 7803, in response to ammonium, nitrate or iron

摘要: An abstract of the dissertation Abbas Sadeghi for Doctor Philosophy in Environmental Sciences and Resources: Biology presented on May 7, 1998. Title: Gene expression two cyanobacteria, freshwater Synechococcus sp. PCC 7942 oceanic WH 7803, response to ammonium, nitrate or iron. The transcriptional 7803 iron was studied single multiple factor limited cultures. Both strains showed maximum production NiR mANA when grown nitrate-containing media. When ammonium-containing medium, they did not show any signal mRNA synthesis. influence transcription by as sole limiting nutrient also evaluated. Iron increased whether positive effect already present. hybridization large subunit ribulose bisphosphate carboxylase/oxygenase enzyme (rbcl), both added. relative NiA larger than that rbcL addition. In final set experiments, combinations iron, limitation were understand their interactive production. ammonium-grown cells allowed starve then transferred +iron+nitrate, +iron-nitrate, -iron+nitrate gradually up 168 hr. initially but, unknown reasons, decreased after 24 hr a minimum similar A comparison from with different time dependent patterns starvation could be experience co-limitation nitrate. This is influenced species specific differences evolutionary adaptation environments. difference confirmed marine (iron) (iron+nitrate) limitation. Physiological studies commonly assume will constrain cell growth at moment conditions change, switch. differential synthesis rbcl observed shows exhibit unique responses combined limitations. GENE EXPRESSION IN TWO CYANOBACTERIA, FRESHWATER SYNECHOCOCCUS SP. AND OCEANIC RESPONSE TO AMMONIUM, NITRATE OR IRON