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The biological pump is a process whereby CO(2) in the upper ocean is fixed by primary producers and transported to the deep ocean as sinking biogenic particles or as dissolved organic matter. The fate of most of this exported material is remineralization to CO(2), which accumulates in deep waters until it is eventually ventilated again at the sea surface.(More)
Assimilation of 3 H-thymidine and 3 H-leucine was examined at the single-cell level using a combination of mi-croautoradiography and fluorescent in situ hybridization (Micro-FISH) to determine the contribution of various bacterial groups to bacterial production in aquatic systems. All of the major phylogenetic groups of bacteria examined along the salinity(More)
We used a method that combines microautoradiography with hybridization of fluorescent rRNA-targeted oligonucleotide probes to whole cells (MICRO-FISH) to test the hypothesis that the relative contributions of various phylogenetic groups to the utilization of dissolved organic matter (DOM) depend solely on their relative abundance in the bacterial community.(More)
Metagenomic studies characterize both the composition and diversity of uncultured viral and microbial communities. BLAST-based comparisons have typically been used for such analyses; however, sampling biases, high percentages of unknown sequences, and the use of arbitrary thresholds to find significant similarities can decrease the accuracy and validity of(More)
The relative contribution of various inorganic and organic forms of nitrogen to the nitrogen requirements of picoplankton was examined with 15N tracers. Size fractionation was used to measure uptake by < l-pm size microorganisms, and inhibitors of protein synthesis were used to separate procaryotic from eucaryotic nitrogen uptake, Picoplankton utilized(More)
The Delaware estuary was sampled at lo-14 stations along the main salinity axis from February to August 1985. Dissolved free and combined amino acid concentrations ranged from 50 nM to 1.4 PM and 0.1 to 8.0 PM, respectively. Combined amino acid concentrations were generally higher than dissolved free amino acids. Highest amino acid concentrations wcrc(More)
Bacterial production rates were estimated for the surface waters of a station 100-m deep in southeastern Lake Michigan during 1984. Production was calculated from incorporation of C3H-methyllthymidine and from empirical conversion factors determined from dilution experiments performed throughout the study. The conversion factors (with typical C.V. ~40%)(More)
We hypothesized that dissolved carbohydrates would be large components of the labile dissolved organic carbon (DOC) pool and would support much bacterial growth in Antarctic waters, especially the Ross Sea, since previous work had observed extensive phytoplankton blooms with potentially high production rates of carbohydrates in Antarctic seas. These(More)
To examine the ecology and evolution of microbial chitinases, especially the chitin-binding domain, one of the chitinase genes (chiA) from the marine bacterium Vibrio harveyi was analysed. The deduced amino acid sequence of ChiA is not very similar overall to other proteins, except for two regions, the putative catalytic and chitin-binding domains. Among(More)