Date of Award

Spring 5-8-2015

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

Committee Chair

Dr. Shahid Karim

Committee Chair Department

Biological Sciences

Committee Member 2

Dr. Tim McLean

Committee Member 2 Department

Biological Sciences

Committee Member 3

Dr. Glen Shearer

Committee Member 3 Department

Biological Sciences

Abstract

Karenia brevis is a toxic marine dinoflagellate that causes harmful algal blooms (HABs), also known as red tides, in the Gulf of Mexico. These blooms are responsible for massive fish kills, shellfish bed contaminations, adverse human health effects, and vast economic loss. For these reasons, extensive research has gone into understanding the mechanisms and dynamics of bloom behavior by studying K. brevis in the field and in the lab. In order to understand higher order bloom behavior and dynamics it is imperative to understand K. brevis at the cellular level. In growing K. brevis in vitro under a variety of conditions, we have noted a distinct shift in the size of both ribosomal RNAs upon culturing cells under “stress” conditions, namely nutritional stress, cold shock, and decreased salinity. When the total RNA is extracted we have detected aberrant rRNA bands on the microcapillary electrophoresis BioAnalyzer (Agilent, Inc.) Interestingly when stressed, the large ribosomal subunit (LSU) becomes larger in size, and the small ribosomal subunit (SSU) becomes smaller. The initial hypothesis was that these aberrant bands were from some intracellular organism which was escaping a dying host. Through microscopy we were not able to support this hypothesis. Subsequently we also considered this response to be something K. brevis does in response to stress. This response by K. brevis had not been previously described in the literature. RNAs, pre- and post-stress, are being fully sequenced to determine how they are different, and what mechanisms may be responsible for producing them: alternative splicing, different transcriptional initiation or termination sites, or different loci? These results will help us understand the molecular events surrounding K. brevis survival under certain environmental conditions, which may have implications regarding K. brevis biogeographical distribution and bloom termination.

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