First study on the effect of UV radiation on spiders: biochemical analysis

Ultraviolet radiation is one of the environmental factors that impacts all living beings and can cause various types of damage. In this study, the effects of UV-B and UV-C radiation on the antioxidant response, reactive oxygen species levels, and potential histological and chromosomal damage were evaluated for the first time in the spider Misumenops maculissparsus at three developmental stages (juveniles J3, J4, and adults). Juveniles exhibited significant inhibition of the antioxidant enzymes superoxide dismutase, catalase, and glutathione-S-transferase under UV radiation exposure. In adults, no enzymatic activity changes were observed, but there were increases in ROS levels, particularly under UV-C exposure, and alterations in the cellular population analyzed by flow cytometry. Histological analysis revealed substantial pigment accumulation beneath the cuticle in juveniles and, to a lesser extent, in adults, which could serve as a natural barrier and antioxidant defense against UV radiation. Cytogenetic analysis determined for the first time in this species a diploid chromosome number of 2n = 23 and identified chromatin granules in UV radiation-exposed adults, suggesting UV radiation-induced chromatin damage. These multidisciplinary findings enhance our understanding of the physiological defenses that spiders employ when exposed to UV radiation at different developmental stages.