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Title: A role for programmed cell death in the microbial loop      
dateReleased:
05-08-2013
description:
The microbial loop is the conventional model by which nutrients and minerals are recycled in aquatic eco-systems. Biochemical pathways in different organisms become metabolically inter-connected such that nutrients are utilized, processed, released and re-utilized by others. The result is that unrelated individuals end up impacting each others’ fitness directly through their metabolic activities. This study focused on the impact of programmed cell death (PCD) on a population’s growth as well as its role in the exchange of carbon between two naturally co-occurring halophilic organisms. Flow cytometric, biochemical, 14C radioisotope tracing assays, and global transcriptomic analyses show that organic algal photosynthate released by Dunalliela salina cells undergoing PCD complements the nutritional needs of other non-PCD D. salina cells. This occurs in vitro in a carbon limited environment and enhances the growth of the population. In addition, a co-occurring heterotroph Halobacterium salinarum re-mineralizes the carbon providing elemental nutrients for the mixoheterotrophic chlorophyte. The significance of this is uncertain and the archaeon can also subsist entirely on the lysate of apoptotic algae. PCD is now well established in unicellular organisms; however its ecological relevance has been difficult to decipher. In this study we found that PCD in D. salina causes the release of organic nutrients such as glycerol, which can be used by others in the population as well as a co-occurring halophilic archaeon. H. salinarum also re-mineralizes the dissolved material promoting algal growth. PCD in D. salina was the mechanism for the flow of dissolved photosynthate between unrelated organisms. Ironically, programmed death plays a central role in an organism’s own population growth and in the exchange of nutrients in the microbial loop. Halobacterium NRC-1 was grown to mid-logarithmic phase (OD600 ~0.4 – 0.8) in MM2. Cells were harvested and washed in MM1 and incubated in MM1 (control) or in Dunaliella harvested supernatant. Cells were harvested at time zero, 5, 10, 20, 40, 80, 160 minutes. RNA from two biological replicate time courses were prepared, averages of these replicates are reported in the published study. The zero time point was harvested immediately after incubation Halobacteria-NRC1 in MM1 or in Dunaliella salina's supernatant.
privacy:
not applicable
aggregation:
instance of dataset
ID:
E-GEOD-45752
refinement:
raw
alternateIdentifiers:
45752
keywords:
functional genomics
dateModified:
06-03-2014
availability:
available
types:
gene expression
name:
Halobacterium sp. NRC-1
ID:
A-GEOD-13682
name:
ISB Halobacterium Spotted Microarray [gene-centered version]
accessURL: https://www.ebi.ac.uk/arrayexpress/files/E-GEOD-45752/E-GEOD-45752.raw.1.zip
storedIn:
ArrayExpress
qualifier:
gzip compressed
format:
TXT
accessType:
download
authentication:
none
authorization:
none
accessURL: https://www.ebi.ac.uk/arrayexpress/files/E-GEOD-45752/E-GEOD-45752.processed.1.zip
storedIn:
ArrayExpress
qualifier:
gzip compressed
format:
TXT
accessType:
download
authentication:
none
authorization:
none
accessURL: https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE45752
storedIn:
Gene Expression Omnibus
qualifier:
not compressed
format:
HTML
accessType:
landing page
primary:
true
authentication:
none
authorization:
none
abbreviation:
EBI
homePage: http://www.ebi.ac.uk/
ID:
SCR:004727
name:
European Bioinformatics Institute
homePage: https://www.ebi.ac.uk/arrayexpress/
ID:
SCR:002964
name:
ArrayExpress