Veldhuis, M. M.. Netherlands Institute for Sea Research, Veldhuis@NIOZ.nl
Kraay, G. M.. Netherlands Institute for Sea Research,
Timmermans, K. K.. Netherlands Institute for Sea Research,
PHYTOPLANKTON IN THE OCEAN: ARE THEY ALL ALIVE?
An assay has been developed to examine the viability of phytoplankton cells and bacteria applying the DNA specific stain SYTOX Green in combination with flow cytometry. The assay is based on the fact that the cellular DNA is stained only in those cells which have lost their membrane integrity, i.e. reduced viability.
Cultures of healthy phytoplankton cells were not stained by the dye. In contrast, senescent cells showed a distinct DNA signal, thus allowing a clear separation between the healthy and dead fraction of the population.
Field samples of phytoplankton collected during spring in the North Atlantic Ocean (40 N, 23 W) showed considerable variation in the viability of the different species examined. The SYTOX live/dead test separated each clusters in positive (dead cells with fully stained DNA) and negative (unstained) subgroups and intermediate stages. This could potentially be related to a Programmed Cell Death (PCD); a gradual process which may take days. On average only 40 to 60% of the phytoplankton population showed no staining suggesting that loss in vitality is an important feature in oceanic phytoplankton with far reaching consequences on productivity, growth rates and the recycling of nutrients.
SS41 SS40: My
Day: Monday, Feb. 1
Time: 04:00 - 04:15pm
Location: Sweeney Center