The effect of benzimidazole on the amino acid composition of the hemolymph of imago Drosophila melanogaster

Background. Habitats are increasingly subjected to anthropogenic press. In order to understand the mechanisms of insect adaptation to widespread xenobiotics, model experiments are needed to determine the response of insects to both highly toxic doses and low toxic doses. The aim of the work was to analyse changes in the amino acid pool under the action of benzimidazole, derivatives of which are widely used in pharmacology and agriculture. Materials and methods. Drosophila melanogaster imago of the wild line Canton-S were exposed daily to benzimidazole at concentrations of: 0.0001 mg/ml and 0.001 mg/ml and LD50 dose. The imago were sedated and 300 each were rubbed in a porcelain mortar with 2 ml of distilled water. The resulting suspension was applied to paper discs for rapid tests. The dried samples were then placed in 0.5 ml plastic tubes and filled with elution liquid (6:4 – methanol: water) and left for 24 hours at room temperature. Sorbfil VETSC plates with a silica gel layer thickness of 160 μm were used for the separation of amino acid mixtures. The mobile phase consisted of the solvent system: n-butanol - glacial acetic acid - water, in a ratio of 3:1:1 by volume. The TLC chamber was charged with 25 mL of mobile phase 1 h before sublimation. Ninhydrin reagent, a universal dye for amino acids, was used for staining. The chromatogram was stained under draught and dried, first at room temperature and then, placed in a desiccator for 1-2 minutes to speed up the manifestation and compared with the test amino acid dispersion. The following amino acids were analysed: tyrosine (Tyr), methionine (Met), alanine (Ala), glycine (Gly), proline (Pro), cysteine (Cys), lysine (Lys), leucine (Leu), valine (Val), ornithine (Orn), histidine (His), threonine (Tre), phenylalanine (Phe). Results. Only 11 amino acids were detected in the control, of all the amino acids analysed, Cys and Lys were missing. Exposure to a non-toxic dose of benzimidazole resulted in a change in the amino acid spectrum in the haemolymph of imago. When exposed to a dose of 0.00001 mg/ml, only: Gly, Pro, Val, Orn, Phe are detected in haemolymph, and when exposed to a dose of 0.001 mg/ml, only: Pro, Val, Orn, Phe are detected, i.e., no Gly is detected. When exposed to benzotriazole at a dose of LD50, the amino acids Val, Hys and Tre disappeared in haemolymph compared to the control, but Cys and Lys appeared, which were absent in the control and when imago were exposed to both non-toxic doses of benzimidazole. Conclusions. The pool of free amino acids in the hemolymph plays an important role in the regulation of the metabolism of Drosophila imagoes. Exposure to benzimidazole at an LD50 dose causes stress in male Drosophila adults, resulting in the appearance of cis and lys. Non-toxic doses also cause changes in the composition of free amino acids, which allows organisms to cope with toxicity. The adaptive potential itself is formed in the process of evolution as a result of the selection of a group of genes that form systems of possible successful adaptive responses.