6533b833fe1ef96bd129b65c

RESEARCH PRODUCT

The response ofAsterochloris erici(Ahmadjian) Skaloud et Peksa to desiccation: a proteomic approach

subject

description

The study of desiccation tolerance of lichens, and of their chlorobionts in particular, has frequently focused on the anti- oxidant system that protects the cell against photo-oxidative stress during dehydration/rehydration cycles. In this study, we used proteomic and transcript analyses to assess the changes associated with desiccation in the isolated phycobiont Aste- rochloris erici. Algae were dried either slowly (5-6 h) or rapidly (<60 min), and rehydrated after 24 h in the desiccated state. To identify proteins that accumulated during the drying or rehydration processes, we employed two-dimensional (2D) difference gel electrophoresis (DIGE) coupled with individual protein identification using trypsin digestion and liquid chromatography-tandem mass spectrometry (LC-MS/ MS). Proteomic analyses revealed that desiccation caused an increase in relative abundance of only 11-13 proteins, regard- less of drying rate, involved in glycolysis, cellular protection, cytoskeleton, cell cycle, and targeting and degradation. Tran- scripts of five Hsp90 and two b-tubulin genes accumulated primarily at the end of the dehydration process. In addition, transmission electron microscopy (TEM) images indicate that ultrastructural cell injuries, perhaps resulting from physical or mechanical stress rather than metabolic damage, were more intense after rapid dehydration. This occurred with no major change in the proteome. These results suggest that desiccation tolerance of A. erici is achieved by constitu- tive mechanisms.