Frischer, M. E. Skidaway Institute of Oceanography, frischer@skio.peachnet.edu
Verity, P. E. Skidaway Institute of Oceanography, peter@skio.peachnet.edu
Williams, S. C. Skidaway Institute of Oceanography, sam@skio.peachnet.edu
Hong, Y. Skidaway Institute of Oceanography, ying@skio.peachnet.edu

 
SIMULTANEOUS USE OF VITAL STAINS AND MOLECULAR PROBES TO ESTIMATE THE IN SITU PHYSIOLOGICAL STATUS OF INDIVIDUAL CELLS IN DIVERSE MARINE ENVIRONMENTS
 
A recently developed semi-automated epifluorescence microscopy technique was used to quantify the abundance of living, dead, and living but inactive cells in various marine environments. This Vital Stain and Probe (VSP) technique simultaneously employs DAPI, the vital stain propidium iodide, and 16S rRNA targeted oligonucleotide probes to quantitatively identify cells with compromised membranes, and cells containing sufficient rRNA to be considered metabolically active. In the South Atlantic Bight, the fraction of dead cells generally increased from nearshore productive waters to offshore oligotrophic waters while the fraction of active cells decreased along this gradient. Changes in the ratio of active:inactive cells were observed over a 24 hour period in estuarine samples. In sub-arctic (Norwegian fjords) samples collected in association with a spring bloom, a sub-surface (40-60 m) maximum in active cells was correlated to the abundance of detritus (r2=0.75). In all environments studied, the fraction of living but low activity cells were large, usually exceeding 50% of the total cells. These observations suggest that living but apparently inactive rather than dead cells are well-represented in marine bacterioplankton populations and imply that bacterioplankton respond rapidly to changing conditions by altering their activity levels.
 
Day: Monday, Feb. 1
Time: 02:15 - 02:30pm
Location: Sweeney Center
 
Code: SS41MO0215S