Picoeukaryotic Plankton Diversity at the Helgoland Time Series Site as Assessed by Three Molecular Methods
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We analyzed picoeukaryote assemblages in the German Bight at the Helgoland time series site by sequencing cloned eukaryotic 18S rRNA genes in six genetic libraries plus one library from the Orkney Islands from a cruise of opportunity. The libraries were constructed from environmental samples collected at different periods of the year. The same samples were also analyzed using a fingerprinting technique, single-strand conformational polymorphism (SSCP), and DNA microarrays with class-level oligonucleotide probes. One hundred unique clones were analyzed from each library, thus insuring over 85% coverage of the library. The V4 region of the 18S rRNA gene was sequenced from each of these clones, thus providing the most discrimination among the clones. The nonphotosynthetic picoeukaryotic component dominated over the photosynthetic one and was represented by the ciliates at 45% and group II alveolates at 42%. Prasinophytes dominated the photosynthetic group at 40%, but other picoplankton groups, such as bolidomonads and chrysophytes, were also present. Totally novel groups were found in the cryptomonads and in the dinoflagellates. A new algal group sister to the cryptophyte nuclear gene and the glaucocystophytes was also found. These three groups have been found in other picoeukaryotic planktonic clone libraries. SSCP analyses at closer time intervals suggest that clone libraries should be made at weekly intervals if succession in the picoeukaryotic plankton community is to be monitored accurately. A comparison of annual samples suggests thatthere appears to be an annual cycle with regard to species composition. Microarray analysis supported the clone library data and offered a faster means of community analysis, which can be performed with similar accuracy and with higher throughput for a more in-depth analysis.
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- 3.B Diez, C Pedros-Alio and R Massana, Study of genetic diversity of eukaryotic picoplankton in different oceanic regions by small-subunit rRNA gene cloning and sequencing. Appl Environ Microbiol 69 (2001) 2340-2443Google Scholar
- 6.HJ Elwood, GJ Olsen and ML Sogin, The small-subunit ribosomal RNA gene sequences from the hypotrichous ciliates Oxytricha nova and Stylonychia pustulata. Mol Biol and Evol 2 (1985) 399-410Google Scholar
- 28.DL Swofford, PAUP*, Phylogenetic Analysis Using Parsimony, Version 4.0 Beta version 8, program and documentation. Champaign, IL, USA: Illinois Natural History Survey, University of Illinois (2002).Google Scholar