Cadmium uptake and defense mechanism in insect cells.
The uptake of cadmium and the defense mechanism against this heavy metal were studied in the Aedes albopictus C6/36 cell line. The internalization of cadmium was a very quick process and exhibited saturation kinetics over the metal concentration gradient (1.37 to 131 micromol/L). Cd toxicity and influx were both shown to be temperature dependent. The uptake was not influenced by a 2, 4-dinitrophenol pretreatment but was significantly decreased by the Ca2+ antagonist verapamil. These data suggest that cadmium is readily taken up through mediated transport, not requiring metabolic energy. A considerable amount of the metal passes through the Ca2+ channels, but probably (an)other transporting molecule(s) also play(s) an important role in the uptake process. The remarkable, nonsigmoid viability pattern of Cd-treated cultures suggests that CdCl2 concentrations above 33 micromol/L induce a cellular defense system. This phenomenon went together with increased protein synthesis. We found a major induction of a group consisting of 71-, 75-, and 78-kDa proteins, probably belonging to the HSP70 family, as similar proteins were induced by heat shock. A slight induction of a 120-kDa protein also occurred. At the highest Cd concentrations 98-, 108-, and 110-kDa proteins were induced. These data suggest that heat shock proteins may play an important role in the Aedes cell protection against Cd insult.
Braeckman
B
B
Physiology and Microbiology, University of Ghent, Ledeganckstraat 35, Ghent, B-9000, Belgium.
Smagghe
G
G
Brutsaert
N
N
Cornelis
R
R
Raes
H
H
D019297:2,4-Dinitrophenol / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000032:analysis; D000330:Aedes / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D002104:Cadmium / Q000032:analysis* / Q000378:metabolism / Q000633:toxicity; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D004785:Environmental Pollutants / Q000032:analysis* / Q000633:toxicity; D013696:Temperature; D014475:Uncoupling Agents / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology
D004785:Environmental Pollutants; D014475:Uncoupling Agents; D002104:Cadmium; D000255:Adenosine Triphosphate; D014700:Verapamil; D019297:2,4-Dinitrophenol