Abstract
We examined the simultaneous incorporation of [3H]thymidine and [14C]leucine to obtain two independent indices of bacterial production (DNA and protein syntheses) in a single incubation. Incorporation rates of leucine estimated by the dual-label method were generally higher than those obtained by the single-label method, but the differences were small (dual/single = 1.1 ± 0.2 [mean ± standard deviation]) and were probably due to the presence of labeled leucyl-tRNA in the cold trichloroacetic acid-insoluble fraction. There were no significant differences in thymidine incorporation between dual- and single-label incubations (dual/ single = 1.03 ± 0.13). Addition of the two substrates in relatively large amounts (25 nM) did not apparently increase bacterial activity during short incubations (<5 h). With the dual-label method we found that thymidine and leucine incorporation rates covaried over depth profiles of the Chesapeake Bay. Estimates of bacterial production based on thymidine and leucine differed by less than 25%. Although the need for appropriate conversion factors has not been eliminated, the dual-label approach can be used to examine the variation in bacterial production while ensuring that the observed variation in incorporation rates is due to real changes in bacterial production rather than changes in conversion factors or introduction of other artifacts.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Bell R. T., Ahlgren G. M., Ahlgren I. Estimating Bacterioplankton Production by Measuring [H]thymidine Incorporation in a Eutrophic Swedish Lake. Appl Environ Microbiol. 1983 Jun;45(6):1709–1721. doi: 10.1128/aem.45.6.1709-1721.1983. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fuhrman J. A., Azam F. Bacterioplankton secondary production estimates for coastal waters of british columbia, antarctica, and california. Appl Environ Microbiol. 1980 Jun;39(6):1085–1095. doi: 10.1128/aem.39.6.1085-1095.1980. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Grivell A. R., Jackson J. F. Thymidine kinase: evidence for its absence from Neurospora crassa and some other micro-organisms, and the relevance of this to the specific labelling of deoxyribonucleic acid. J Gen Microbiol. 1968 Dec;54(2):307–317. doi: 10.1099/00221287-54-2-307. [DOI] [PubMed] [Google Scholar]
- Hobbie J. E., Daley R. J., Jasper S. Use of nuclepore filters for counting bacteria by fluorescence microscopy. Appl Environ Microbiol. 1977 May;33(5):1225–1228. doi: 10.1128/aem.33.5.1225-1228.1977. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kirchman D., Ducklow H., Mitchell R. Estimates of bacterial growth from changes in uptake rates and biomass. Appl Environ Microbiol. 1982 Dec;44(6):1296–1307. doi: 10.1128/aem.44.6.1296-1307.1982. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kirchman D., K'nees E., Hodson R. Leucine incorporation and its potential as a measure of protein synthesis by bacteria in natural aquatic systems. Appl Environ Microbiol. 1985 Mar;49(3):599–607. doi: 10.1128/aem.49.3.599-607.1985. [DOI] [PMC free article] [PubMed] [Google Scholar]
- McDonough R. J., Sanders R. W., Porter K. G., Kirchman D. L. Depth distribution of bacterial production in a stratified lake with an anoxic hypolimnion. Appl Environ Microbiol. 1986 Nov;52(5):992–1000. doi: 10.1128/aem.52.5.992-1000.1986. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Riemann B. Potential importance of fish predation and zooplankton grazing on natural populations of freshwater bacteria. Appl Environ Microbiol. 1985 Aug;50(2):187–193. doi: 10.1128/aem.50.2.187-193.1985. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Tremaine S. C., Mills A. L. Tests of the critical assumptions of the dilution method for estimating bacterivory by microeucaryotes. Appl Environ Microbiol. 1987 Dec;53(12):2914–2921. doi: 10.1128/aem.53.12.2914-2921.1987. [DOI] [PMC free article] [PubMed] [Google Scholar]