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Diurnal Variation of Cell Proliferation in Three Bacterial Taxa from Coastal North Sea Waters

Pernthaler, Annelie and Perthaler, Jakob (2005) Diurnal Variation of Cell Proliferation in Three Bacterial Taxa from Coastal North Sea Waters. Applied and Environmental Microbiology, 71 (8). pp. 4638-4644. ISSN 0099-2240. http://resolver.caltech.edu/CaltechAUTHORS:PERaem05

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Abstract

Pulse-labeling with bromodeoxyuridine (BrdU) in combination with fluorescence in situ hybridization was applied to quantify the percentage of proliferating cells in coastal North Sea waters. In order to assess diurnal variability, we sampled eight or nine times, respectively, within 3 consecutive days at two seasons. Bacteria affiliated with the Roseobacter, SAR86, and NOR5 lineages constituted on average 19% ± 3%, 8% ± 2%, and 6% ± 1% of all cells in May 2002 and 17% ± 3%, 10% ± 2%, and 11% ± 3% in August. The relative abundances of the three populations either remained stable, or they changed very gradually during the observation periods. On average, 38 and 39% of all Bacteria exhibited DNA de novo synthesis in May and August, respectively. The fractions of proliferating cells in bacteria of the SAR86 (May, 59%; August, 72%) and the Roseobacter (48 and 53%) lineages were significantly above the community average. A substantial cell proliferation of population NOR5 (34%) was only encountered in August, concomitant with a dinoflagellate bloom. Significant short-term fluctuations of DNA-synthesizing cells were observed in Roseobacter during May and in NOR5 during August, hinting at a pronounced (temporal or spatial) mesoscale patchiness of growth rates in these populations. Since the BrdU proliferation assay is susceptible to misinterpretation, we also modeled the expected number of labeled cells at increasing BrdU incubation times in a slowly growing bacterial population. We suggest that the absence of visible DNA synthesis in marine bacterioplankton cells after DNA pulse-labeling must not be interpreted as an indication of cell "inactivity."


Item Type:Article
Additional Information:Copyright © 2005, American Society for Microbiology. Received 21 December 2004/Accepted 14 February 2005. We thank Gunnar Gerdts and Antje Wichels from the Biological Station Helgoland of the Alfred-Wegener Institute for kindly providing lodging, laboratory facilities, and sampling devices (Pütz & Tampen). Martha Schattenhofer is acknowledged for help during sample evaluation. This project was financed by the European Union (EVK3-2001-00194 BASICS) and by the Max Planck Society.
Record Number:CaltechAUTHORS:PERaem05
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:PERaem05
Alternative URL:http://dx.doi.org/10.1128/AEM.71.8.4638-4644.2005
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:6838
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:26 Dec 2006
Last Modified:26 Dec 2012 09:25

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