The Collier lab is using quantitative reverse transcription PCR (QRT-PCR) to examine the expression of several genes in the cyanobacterium Synechocystis PCC6803 that have been predicted by means of a novel Bayesian algorithm to be regulated by a common mechanism. Several of these genes are predicted to be controlled by the global nitrogen regulator NtcA, so expression levels are being quantified in nitrate- versus ammonium-grown cells. As part of the Biocomplexity project, the Collier lab is using TRFLP (terminal restriction fragment length polymorphism) to investigate the identity and diversity of the microorganisms that are responsible for the biogeochemical cycling of urea in Chesapeake Bay. We will also be investigating how the number of PCR cycles and other aspects of the TRFLP procedure affect the results and appearance of artifacts.