The thesis is focused on the biochemical markers determined in
terrestrial gastropods and earthworms. These soil invertebrates
are in constant contact with a large amount of toxic
substances, which appear in the environment. The exposure to
these substances may have a negative effect on the organism.
The changes in the body caused by the action of xenobiotics are
evaluated using biomarkers. Cholinesterase is a family of
enzymes frequently used as biomarkers. These enzymes are used
as specific biomarkers of exposure to the organophosphate
pesticides. One of the commonly used organophosphate is
chlorpyrifos. This substance may have a negative effect on
non-target organisms, one of which are soil invertebrates. The
experimental part of this diploma thesis is focused on the
determination of cholinesterase activity in different tissues
of the snail Helix aspersa (head, hemolymph, hepatopancreas,
and albumin gland) and the earthworm Eisenia fetida (head,
body). It was focused especially on the optimization of the
methodology used for measuring cholinesterase using Ellman
method and also on the determination of physiological levels
and kinetic parameters (Michaelis constant, catalytic
efficiency) of acetylcholinesterase (AChE),
butyrylcholinesterase (BChE,) and propionylcholinesterase
(PChE) in snails Helix aspersa and earthworms Eisenia fetida.
In vitro exposure to the commercially-produced pesticide
Nurelle D was used to evaluate the effect of organophosphate
chlorpyrifos on cholinesterase activity. The results indicate a
high variability of AChE, BChE and PChE activity between the
snails Helix aspersa and the earthworms Eisenia fetida. The
highest activity in gastropod was generally measured in their
hemolymph, while it was significantly lower in the other
tissues. The lowest cholinesterase activity was measured in the
albumin gland and hepatopancreas. The enzyme activity in
earthworms had very similar values in the head and the body.
The catalytic efficiency was the highest for AChE and the
lowest for BChE in both organisms. The presence of
organophosphate chlorpyrifos in all samples caused inhibition
of AChE, BChE and PChE in almost all tissues in both organisms.
Nevertheless, the more sensitive response was shown in the
snails Helix aspersa.