DNA damage in haemocytes and midgut gland cells of Steatoda grossa (Theridiidae) spiders exposed to food contaminated with cadmium

• The genotoxic effect of Cd in spiders is sex- and internal organ-dependent.
• Haemocytes are more sensitive to cadmium than midgut gland cells.
• The level of DNA damage in midgut gland cells is higher for males than females.

The aim of this study was to assess the genotoxic effects of Cd on haemocytes and midgut gland cells of web-building spiders, Steatoda grossa (Theridiidae), exposed to the metal under laboratory conditions. Analyzes were conducted on adult females and males, fed for four weeks with cadmium-contaminated Drosophila hydei flies, grown on a medium suplemented with 0.25 mM CdCl2. The comet assay, providing a quantitative measure of DNA strand breaks, was used to evaluate the DNA damage caused by the metal. Cadmium content was measured in whole spider bodies by the AAS method. Metal body burden was significantly lower in females (0.25 µg g−1 dry weight) than in males (3.03 µg g−1 dry weight), suggesting that females may have more effective mechanisms controlling the uptake of metal, via the digestive tract, or its elimination from the body. Irrespectively of sex, spiders fed prey contaminated with cadmium showed significantly higher values of comet parameters: tail DNA (TDNA), tail length (TL) and olive tail moment (OTM), in comparison with the control. In midgut gland cells, the level of DNA damage was higher for males than females, while in haemocytes the genotoxic effect of cadmium was greater in females. The obtained results indicate that in spiders cadmium displays strong genotoxic effects and may cause DNA damage even at low concentrations, however the severity of damage seems to be sex- and internal organ-dependent.The comet assay can be considered a sensitive tool for measuring the deleterious effect of cadmium on DNA integrity in spiders.