MEASUREMENT OF IN SITU EXPRESSION OF PROTEORHODOPSIN GENES AT THE NORTH PACIFIC CENTRAL GYRE STATION ALOHA

Abstract

A novel approach was developed for the measurement of microbial gene expression in the oceans, and used to test the hypothesis that Proteorhodopsin (PR) gene expression is regulated at the transcriptional level. Chapter 1 describes the optimization of total nucleic-acid extraction that allows "quasi-absolute" quantification of PR mRNAs and coding genes, and the subsequent use of mRNA to gene ratio as a measure of PR gene transcription. In Chapter 2, I describe the construction of a PR cDNA clone library using an RNA sample collected from the North Pacific Central Gyre Station ALOHA, from which diverse PR gene sequences were retrieved and subjected to phylogenetic analyses based on the amino acid sequences. Chapter 3 describes the measurement of in situ PR gene transcription during three diel cycles. Light availability and physical processes such as advection were both found to affect measured PR gene transcription at 25 m at station ALOHA.