|
2004
LSU-HHMI Summer Undergraduate Research Program |
| |
 Celeste
Gary, David Longstreth, Biological Sciences
Secretion of a Small protein is Stimulated During Salt Adaptation
of Suspension Cells from Alternanthera philoxeroides
Our overall goal was to identify secreted proteins that are
unique to salt-adapted suspension cultures of Alternanthera
philoxeroides, alligator weed. Secreted proteins may be part
of an adaptive response to an increase in salinity. Whole plants
and cell-suspension cultures of A. philoxeroides tolerate increases
in salinity that kill other plant species. Photomixotrophic
(light grown) or heterotrophic (dark grown) suspension cells,
not previously exposed to high NaCl concentrations, were sub-cultured
in nutrient media or nutrient media with 200 mM NaCl. Cells
were separated from media by filtration and centrifugation.
Proteins in the media were precipitated with 60% (NH4)2SO4,
made soluble in a small volume of 200 mM sodium acetate buffer
and dialyzed to produce concentrated protein samples. The soluble
cell proteins were extracted by grinding the cells in buffer.
Both the secreted proteins and the cell proteins were separated
using sodium dodecyl sulfate polyacrylamide gel electrophoresis
(SDS-PAGE). No differences were found between the control and
salt media proteins from the photomixotrophic cells. The most
striking difference in banding patterns of the secreted proteins
from the heterotrophic cells was the presence of a small polypeptide
(approximately 22 kD in size) in high-salt media that appears
absent in control media.
|
|
|
