Advancing monosaccharides as biomarkers: Part II. Effects of starvation and cadmium in Chironomus riparius as detected by fluorophore-assisted carbohydrate-electrophoresis

Abstract

Saccharides were evaluated as biomarkers for cadmium (Cd) and starvation using fluorophore-assisted carbohydrate-electrophoresis (FACE) in 4th instar Chironomus riparius. FACE allowed different types of saccharides in whole larval homogenate to be analyzed simultaneously and in parallel with other larval samples. Larval homogenates showed seven principle bands labeled A, B, C, D, E, F and G. Previous work found that the migration patterns of bands A, C, D and F matched those of ribose, glucose, galactose and fructose, respectively. Four of the bands, B, C, E and G were generated from glucose-based mono, oligo, and polysaccharides. Band B was primarily derived from glucose and band E from glycogen. Experiments (0–72 h) with starved larvae showed a time dependent reduction in bands B and E that was statistically significant at 72 h. Experiments with Cd (0.01–1000 μM) showed a concentration and time dependent reduction in band E with a LOEL of 1 μM and NOEL of 0.01 μM at 48 h. The LOEL was 0.014% of the 48 h LC50. Significant reduction of band E only occurred in fed larvae indicating that food was an important route of exposure. Reductions in saccharides were independent of larval weight loss at 48 h. This suggested that major changes in saccharides were not due to weight loss but metabolic stress in the presence of Cd.