title: Changes in protein content and free amino acid composition in metal-contaminated gypsy moth larvae (Lymantria dispar L., Lymantriidae, Lepidoptera).
abstract: Larvae of Lymantria dispar (Lymantriidae, Lepidoptera) were either reared on oak foliage or on an uncontaminated and metal-contaminated wheat germ diet from hatching to the end of experiment. Cd, Pb, Cu and Zn were separately applied, each at two concentrations in the range of no-observed-effect concentrations recently published for this species. Hemolymph was collected from day 3 fourth instar larvae, and total protein content and free amino acid composition were determined along with total body protein content (TBP) of the corresponding larvae. Clear diet-dependent differences were observed: total protein content of the larvae and of the hemolymph was higher in foliage-fed (281.2 micrograms/mg; 13.6 mg/ml) than in diet-fed control individuals (200.5 micrograms/mg; 10.5 mg/ml), whereas the opposite applied to the total free amino acid (TFAA) concentration (64.78 mM, 108.81 mM). Chronic exposure to Cd, Cu and Zn in the diet generally resulted in a decrease of total hemolymph protein but enhanced TFAA concentrations and TBP compared with artificial-diet-fed control group. Sixteen free amino acids were identified and quantitated by high-performance liquid chromatography. Concentrations of single amino acids and/or their relative abundance depended on the diet and the metal applied. For example, the concentration of histidine, the most abundant amino acid (40-53% of total amino acids), was lower in the oak-leaf-fed group (26.04 mM, 40.8% of total amino acids) than in the wheat germ control group (47.89 mM, 44%), but in most metal-contaminated specimens histidine increased significantly (56.58-69.78 mM, 46-53%). The phenylalanine concentration was not diet dependent but was the only amino acid elevated in all contaminated groups.
authors.affiliation: Abt. Okophysiologie/Stoffwechselphysiologie, University of Vienna, Austria.
authors.forename: J
authors.initials: J
authors.lastname: Ortel
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D000821:Animal Feed / Q000032:analysis; D000818:Animals; D006458:Hemolymph / Q000737:chemistry; D008670:Metals / Q000378:metabolism / Q000633:toxicity*; D009036:Moths / Q000187:drug effects*; D011506:Proteins / Q000032:analysis*
chemical_list: D000596:Amino Acids; D008670:Metals; D011506:Proteins