Project: Labyrinthulomycete diversity and abundance

The following description is an excerpt from the NSF award abstract:
The Labyrinthulomycetes (labyrinthulids, thraustochytrids, and aplanochytrids) are ubiquitous, diverse, and abundant marine protists. They are thought to live mainly as saprobes, obtaining their nutrition from non-living particulate organic matter (POM) of algal, higher plant, or animal origin. Thus, while Labyrinthulomycetes are not "fungi" in a taxonomic sense, they may function as "fungi" in an ecological sense, playing similar roles in the decomposition of POM. Because of their high content of essential polyunsaturated fatty acids (PUFAs), Labyrinthulomycetes may also play a role in the nutrition of marine metazoans by improving the food quality of detritus ("trophic upgrading"). However, evidence of their role decomposing marine POM is somewhat circumstantial, and thus does not support quantitative conclusions about their function or importance. The long-term goal of this project is to gather the evidence about Labyrinthulomycete abundance and diversity that will be needed to better understand their role in marine ecosystems.

This project aims to develop molecular genetic methods based on the polymerase chain reaction (PCR) to investigate the diversity and abundance of Labyrinthulomycetes. The existing Labyrinthulomycete-specific PCR primers for 18S ribosomal DNA (rDNA) cannot recognize a potentially important component of Labyrinthulomycete diversity (some groups of thraustochytrids). The investigators will develop new 18S rDNA primers that will allow better estimation of the diversity of the Labyrinthulomycetes, and then use these primers to gather 18S rDNA sequence data from a variety of habitats. The resulting sequence data will diversity of these organisms to be quantified in the field relative to the representatives currently in culture. These primers (or others designed in the course of the project) will be used to develop quantitative real-time PCR assays to determine the abundance of Labyrinthulomycetes (and subgroups of Labyrinthulomycetes) in environmental samples. Methods will also be developed to cultivate novel Labyrinthulomycetes detected in local sediments during the preliminary sequencing efforts.