Record Details

Docosahexaenoic acid accumulation in hraustochytrids: Search for the rationale

DRS at CSIR-National Institute of Oceanography

View Archive Info
 
 
Field Value
 
Title Docosahexaenoic acid accumulation in hraustochytrids: Search for the rationale
 
Creator Jain, R.
Raghukumar, S.
Sambaiah, K.
Kumon, Y.
Nakahara, T.
 
Subject microorganisms
protists
acids
bioaccumulation
lipids
developmental stages
starvation
water column
 
Description Thraustochytrid protists characteristically accumulate high amounts of lipids, much of which is comprised of the polyunsaturated fatty acid, docosahexaenoic acid (DHA). Since DHA is important in human health, thraustochytrids have attracted much attention from the point of view of biotechnology. However, the biological rationale of DHA production in the storage lipids of these organisms is not clear. Three experiments were carried out to study this. (1) The fate of lipids in thraustochytrids during development was studied by staining lipids of vegetative cells with the fluorescent vital stain for lipids, namely Nile blue, following the growth of the cells. The fluorescent lipid bodies decreased in abundance in freshly formed motile limaciform amoeboid cells and subsequently disappeared when they moved away. When vegetative cells produced vast extensions of plasma membrane, the ectoplasmic net elements (EN), the fluorescent lipids appeared to be transported to them. (2) Changes in lipids and DHA during starvation were examined in cells with enhanced lipid and DHA contents and those in which they were not enhanced. Cells in which lipids and DHA were enhanced by refrigerating them for 48 h survived starvation for a longer period. Compared to cells that had not been refrigerated, total fatty acids, as well as DHA were marginally higher in pre-refrigerated cells, while palmitic acid levels were lower. Starvation of cells resulted in a gradual decrease of absolute concentrations and percentage levels of DHA after 8 days, while percentage of palmitic acid levels increased. (3) The relationship between DHA and specific gravity of cells was studied by comparing cells pre-refrigerated as above with those, which were not pre-refrigerated. Refrigerated cells with increased lipids and DHA showed higher specific gravities than nonrefrigerated cells. The following roles are suggested for storage lipids and DHA in thraustochytrids: (1) lipids serve as energy sources during movement of cells and for production of EN; (2) DHA in storage lipids become distributed in the plasma membrane when EN are formed; (3) DHA is preferably utilized as a fatty acid energy reserve during starvation and (4) an unknown mechanism results in negative buoyancy of cells when total lipids and DHA are marginally enhanced. DHA in storage lipids might be crucial to the survival of thraustochytrid cells.
 
Date 2008-01-30T13:51:11Z
2008-01-30T13:51:11Z
2007
 
Type Journal Article
 
Identifier Marine biology, Vol.151; 1657-1664p.
http://drs.nio.org/drs/handle/2264/687
 
Language en
 
Publisher Springer