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Please use this identifier to cite or link to this item: http://hdl.handle.net/10261/15586
Title: Distribution of the uncultured protist MAST-4 in the Indian Ocean, Drake Passage and Mediterranean Sea assessed by real-time quantitative PCR
Authors: Rodríguez-Martínez, Raquel; Labrenz, Matthias; Campo, Javier del; Forn, Irene; Jürgens, Klaus; Massana, Ramon
Issue Date: Feb-2009
Publisher: Society for Applied Microbiology
Blackwell Publishing
Citation: Environmental Microbiology 11(2): 397-408 (2009)
Abstract: Molecular surveys of marine picoeukaryotes have revealed a large number of sequences unrelated to cultured organisms, such as those forming the marine stramenopile (MAST)-4 clade. Recent FISH (fluorescent in situ hybridization) data have shown that MAST-4 cells are uncultured heterotrophic flagellates of 2–3 μm in size that have a global distribution in non-polar marine waters. However, FISH is time-consuming and hard to apply to the many samples generated during oceanographic cruises, so we developed a real-time quantitative polymerase chain reaction (Q-PCR) protocol to determine rapidly the abundance of this group using environmental DNA. We designed a primer set targeting the 18S rRNA genes (rDNA) of MAST-4 and optimized and calibrated the Q-PCR protocol using a plasmid with the target sequence as insert. The Q-PCR was then applied to quantify MAST-4 rDNA molecules along three marine transects, longitudinal in the Indian Ocean, latitudinal in the Drake Passage and coastal–offshore in the Mediterranean Sea, and to a temporal study in a Mediterranean Sea coastal station. MAST-4 was detected in all samples processed (averaged abundances between 500 and 1000 rDNA molecules ml−1) except in mesopelagic and Antarctic samples, where it was virtually absent. In general, it was more abundant in the coast than offshore and in the deep chlorophyll maximum than at surface. A comparison of Q-PCR and FISH signals in well-controlled microbial incubations indicated that MAST-4 cells have around 30 copies of the rDNA operon. This Q-PCR assay quickly yielded quantitative data of uncultured MAST-4 cells and confirmed their wide distribution and putative ecological importance.
Description: 12 pages, 5 figures, 1 table.-- Available online Oct 6, 2008.-- Full-text version available Open Access at: http://www.icm.csic.es/bio/projects/icmicrobis/pdf/Rodriguez-Martinez09.pdf
Publisher version (URL): http://dx.doi.org/10.1111/j.1462-2920.2008.01779.x
URI: http://hdl.handle.net/10261/15586
ISSN: 1462-2912
DOI: 10.1111/j.1462-2920.2008.01779.x
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