engleski

Expression of HSP70 isoforms in Lemna minor exposed to cadmium and salinity

Heat shock proteins belonging to the HSP70 family have been proposed as a biochemical marker of environmental stress because they are induced by a broad range of stress factors (Neumann et al., 1994). Lemna minor is aquatic macrophyte widely used for toxicity evaluation due to numerous advantages, but mostly growth parameters have been used (Lewis 1995). The objective of this study was to determine expression of HSP70 in Lemna minor exposed to haevy metal and salinity. Duckweed Lemna minor was grown 14 days in axenic and controlled conditions on media with 0.01 mM CdCl2 or 100 mM NaCl. Plant extracts were made in Tris/HCl buffer pH 8.0 (Staples and Stahmann 1964) and protein content was determined (Bradford 1976). Proteins were separated by SDS-PAGE (Laemmli 1970) and electroblotted to nitrocellulose membranes (Towbin et al., 1979). Membranes were probed with a polyclonal antibody to plant HSP70. Western blot analysis of plants grown 14 days in presence of 0.01 mM cadmium or 100 mM NaCl showed expression of two HSP70 isoforms, 80 kDa and 78 kDa. In control plants as well as in plants shortly exposed to stresses (6 days) only isoform of 80 kDa was noticed. Our results suggest that expression of HSP70 is common response to different stresses so it can be used as a biochemical marker of environmental stress using Lemna minor as test organism. References: Bradford MM. 1976. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem 72 ; 248-254. Laemmli UK. 1970. Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature 227 ; 680-685. Lewis MA. 1995. Use of freshwater plants for phytotoxycity testing: A review. Environ Poll 87 ; 319-336. Neumann D, Lichtenberger O, Gunther D, Tschiersch K, Nover L. 1994. Heat-shock proteins induce heavy-metal tolerance in higher plants. Planta 194 ; 360-367. Towbin H, Staehelin T, Gordon J. 1979. Electrophoretic transfer of proteins from polyacrylamide gels to nitrocellulose sheets: procedure and some applications. Proc Natl Acad Sci USA 76 ; 4350-4354. Staples RC, Stahmann MA. 1964. Changes in proteins and several enzymes in susceptible bean leaves after infection by the bean rust fungus. Phytopatology 54 ; 760-764.

heat shock proteins; Lemna minor; salinity; cadmium

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