scholarly journals Diel changes in bacterial biomass and growth rates in coastal environments, determined by means of thymidine incorporation into DNA, frequency of dividing cells (FDC), and microautoradiography

1984 ◽  
Vol 17 ◽  
pp. 227-235 ◽  
Author(s):  
B Riemann ◽  
P Nielsen ◽  
M Jeppesen ◽  
B Marcussen ◽  
JA Fuhrman
Keyword(s):  
Growth Rates ◽  
Thymidine Incorporation ◽  
Bacterial Biomass ◽  
Coastal Environments ◽  
Diel Changes ◽  
Dividing Cells

scholarly journals Rapid Determination of Bacterial Abundance, Biovolume, Morphology, and Growth by Neural Network-Based Image Analysis

1998 ◽  
Vol 64 (9) ◽  
pp. 3246-3255 ◽  
Author(s):  
Nicholas Blackburn ◽  
Åke Hagström ◽  
Johan Wikner ◽  
Rocio Cuadros-Hansson ◽  
Peter Koefoed Bjørnsen
Keyword(s):  
Neural Network ◽  
Image Analysis ◽  
Bacterial Growth ◽  
Growth Rates ◽  
Bacterial Abundance ◽  
Rapid Determination ◽  
Image Analyzer ◽  
Cell Counts ◽  
Dividing Cells ◽  
Bacterial Growth Rates

ABSTRACT Annual bacterial plankton dynamics at several depths and locations in the Baltic Sea were studied by image analysis. Individual bacteria were classified by using an artificial neural network which also effectively identified nonbacterial objects. Cell counts and frequencies of dividing cells were determined, and the data obtained agreed well with visual observations and previously published values. Cell volumes were measured accurately by comparison with bead standards. The survey included 690 images from a total of 138 samples. Each image contained approximately 200 bacteria. The images were analyzed automatically at a rate of 100 images per h. Bacterial abundance exhibited coherent patterns with time and depth, and there were distinct subsurface peaks in the summer months. Four distinct morphological classes were resolved by the image analyzer, and the dynamics of each could be visualized. The bacterial growth rates estimated from frequencies of dividing cells were different from the bacterial growth rates estimated by the thymidine incorporation method. With minor modifications, the image analysis technique described here can be used to analyze other planktonic classes.

scholarly journals Spatial and Temporal Variations in Chitinolytic Gene Expression and Bacterial Biomass Production during Chitin Degradation

2000 ◽  
Vol 66 (8) ◽  
pp. 3574-3585 ◽  
Author(s):  
Ace M. Baty ◽  
Callie C. Eastburn ◽  
Somkiet Techkarnjanaruk ◽  
Amanda E. Goodman ◽  
Gill G. Geesey
Keyword(s):  
Gene Expression ◽  
Aqueous Phase ◽  
Growth Rates ◽  
Bacterial Production ◽  
Silicon Surface ◽  
Specific Growth ◽  
Bacterial Biomass ◽  
Silicon Surfaces ◽  
Surface Colonization ◽  
Specific Growth Rates

ABSTRACT Growth of the chitin-degrading marine bacterium S91 on solid surfaces under oligotrophic conditions was accompanied by the displacement of a large fraction of the surface-derived bacterial production into the flowing bulk aqueous phase, irrespective of the value of the surface as a nutrient source. Over a 200-h period of surface colonization, 97 and 75% of the bacterial biomass generated on biodegradable chitin and a nonnutritional silicon surface, respectively, detached to become part of the free-living population in the bulk aqueous phase. Specific surface-associated growth rates that included the cells that subsequently detached from the substrata varied depending on the nutritional value of the substratum and during the period of surface colonization. Specific growth rates of 3.79 and 2.83 day−1 were obtained when cells first began to proliferate on a pure chitin film and a silicon surface, respectively. Later, when cell densities on the surface and detached cells as CFU in the bulk aqueous phase achieved a quasi-steady state, specific growth rates decreased to 1.08 and 0.79 day−1 on the chitin and silicon surfaces, respectively. Virtually all of the cells that detached from either the chitin or the silicon surfaces and the majority of cells associated with the chitin surface over the 200-h period of surface colonization displayed no detectable expression of the chitin-degrading genes chiA and chiB. Cells displaying high levels of chiA-chiB expression were detected only on the chitin surface and then only clustered in discrete areas of the surface. Surface-associated, differential gene expression and displacement of bacterial production from surfaces represent adaptations at the population level that promote efficient utilization of limited resources and dispersal of progeny to maximize access to new sources of energy and maintenance of the population.

scholarly journals Biomass Production and Assimilation of Dissolved Organic Matter by SAR11 Bacteria in the Northwest Atlantic Ocean

2005 ◽  
Vol 71 (6) ◽  
pp. 2979-2986 ◽  
Author(s):  
Rex R. Malmstrom ◽  
Matthew T. Cottrell ◽  
Hila Elifantz ◽  
David L. Kirchman
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Atlantic Ocean ◽  
Dissolved Organic Matter ◽  
Biomass Production ◽  
Growth Rates ◽  
Bacterial Biomass ◽  
Leucine Incorporation ◽  
Northwest Atlantic ◽  
Specific Growth Rates

ABSTRACT Members of the SAR11 clade often dominate the composition of marine microbial communities, yet their contribution to biomass production and the flux of dissolved organic matter (DOM) is unclear. In addition, little is known about the specific components of the DOM pool utilized by SAR11 bacteria. To better understand the role of SAR11 bacteria in the flux of DOM, we examined the assimilation of leucine (a measure of biomass production), as well as free amino acids, protein, and glucose, by SAR11 bacteria in the Northwest Atlantic Ocean. We found that when SAR11 bacteria were >25% of total prokaryotes, they accounted for about 30 to 50% of leucine incorporation, suggesting that SAR11 bacteria were major contributors to bacterial biomass production and the DOM flux. Specific growth rates of SAR11 bacteria either equaled or exceeded growth rates for the total prokaryotic community. In addition, SAR11 bacteria were typically responsible for a greater portion of amino acid assimilation (34 to 61%) and glucose assimilation (45 to 57%) than of protein assimilation (≤34%). These data suggest that SAR11 bacteria do not utilize various components of the DOM pool equally and may be more important to the flux of low-molecular-weight monomers than to that of high-molecular-weight polymers.

scholarly journals Immunohistochemical identification of proliferating cells in organ culture using bromodeoxyuridine and a monoclonal antibody.

1986 ◽  
Vol 34 (6) ◽  
pp. 697-701 ◽  
Author(s):  
G Morstyn ◽  
K Pyke ◽  
J Gardner ◽  
R Ashcroft ◽  
A de Fazio ◽  
...  
Keyword(s):  
Organ Culture ◽  
Cancer Biology ◽  
Thymidine Incorporation ◽  
Optical Data ◽  
Proliferating Cells ◽  
Fetal Mouse ◽  
Mouse Colon ◽  
Dividing Cells ◽  
Immunohistochemical Identification

The ability to measure cell proliferation is important in the study of cancer biology. The usual technique for quantitating proliferating cells in tissue explant and organ culture by detection of [3H]-thymidine incorporation into DNA by autoradiography is tedious and time-consuming. We have developed a technique for identification and quantitation of bromodeoxyuridine (an analogue of thymidine) in cultured tissue explants. Fetal mouse colon explants were exposed in vitro to bromodeoxyuridine (BUdR) or [3H]-thymidine for 3 to 72 hr and then for various periods to unlabeled thymidine. The tissues were stained with a monoclonal anti-bromodeoxyuridine antibody and in parallel [3H]-thymidine incorporation was detected by autoradiography. Incorporation of BUdR was measured by quantitating the amount of pigment deposited over nuclei after immunohistochemical staining, using an optical data digitizer. It was found that both techniques identified proliferating cells. Dividing cells were present both in crypts and in the surrounding stroma in Day 14 fetal mouse colon cultures. The immunohistochemical technique was more rapid and less cumbersome than autoradiography.

Variations spatio-temporelles de l'abondance et de la production du bactérioplancton dans un lac humique du Bouclier canadien

1991 ◽  
Vol 37 (1) ◽  
pp. 64-73 ◽  
Author(s):  
Yvon Letarte ◽  
Bernadette Pinel-Alloul
Keyword(s):  
Bacterial Production ◽  
Thymidine Incorporation ◽  
Small Scale ◽  
Bacterial Cells ◽  
Spatiotemporal Variations ◽  
Bacterioplankton Production ◽  
Renewal Time ◽  
Dividing Cells ◽  
Bouclier Canadien ◽  
Bacterioplankton Abundance

We followed the diel and summer variations of bacterioplankton production (estimated from [3H] thymidine incorporation) and abundance (direct count with 4′,6-diamidino-2-phenylindole staining) at four depths in a Canadian Shield humic lake. We found production to be highest and most variable in the epilimnion, but the differences between production estimates made at different times were statistically significant in only 5 out of 16 cases. Production differed significantly among depths in 14 out of 18 trials. The renewal time of the bacterial community varied between 1 and 20 days. Bacterioplankton production and primary production were uncorrelated (r = 0.225; p > 0.2), but bacterial production and chlorophyll a concentration were positively correlated (r = 0.816; p < 0.005). Small coccis (~0.3 – ~0.8 μm) represented between 52 and 80% of the bacterial cells in all the samples. There was no correspondence between bacterial production and frequency of dividing cells. Bacterial production and abundance varied inversely throughout the season, bacteria being two to three times less concentrated in the spring, whereas production was two to three times higher. We found no correlation between bacterioplankton production and abundance (r = 0.012; p > 0.5). Our results demonstrate the importance of small-scale sampling and the difficulty with which bacterioplankton production, its spatiotemporal variations, and the relationships between bacteria and phytoplankton can be predicted. Key words: bacterioplankton, abundance, production, spatiotemporal variations, bacterioplankton–phytoplankton relationships.

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