Ecophysiological responses of Liolaemus arambarensis juveniles to experimental temperature variations.

Climate change increasingly influences the loss of biodiversity, especially in ectothermic organisms, which depend on environmental temperatures to obtain heat and regulate their life cycle. Studies that aim to understand the impact of temperature variation are important to better understand the possible impacts generated on the homeostasis of ectothermic organisms. Our objective was to characterize the responses of juvenile Liolaemus arambarensis lizards to abrupt changes in temperature, quantifying markers of body condition, intermediary and hormonal metabolism and oxidative balance. We collected 45 juvenile individuals of L. arambarensis (winter: 20 and summer: 25) in Barra do Ribeiro, Brazil. We transported the animals to the laboratory, where they were acclimatized for five days at a temperature of 20 °C, then divided and exposed to temperatures of 10 °C, 20 °C, 30 °C and 40 °C for 24 h. After exposure, the animals were euthanized and the brain, caudal muscle, thigh, and liver tissues were extracted for quantification of biomarkers of metabolism (glycogen and total proteins) and oxidative balance (acetylcholinesterase, superoxide dismutase, catalase, glutathione-S-transferase and lipoperoxidation) and plasma for corticosterone quantification. The results show that L. arambarensis is susceptible to sudden temperature variations, where higher temperatures caused greater activity of antioxidant enzymes, increased lipoperoxidation and higher plasma levels of corticosterone in animals eliminated in winter. The present study demonstrated that abrupt changes in temperature could significantly modify the homeostatic mechanisms of animals, which could lead to oxidative stress and a potential trade-off between survival and growth/reproduction. In this context, the organism mobilizes energy resources for survival, with possible damage to growth and reproduction. Demonstrate that a change in temperature can be a potential factor in extinction for a species given the profile of global climate change.

Impact of 2,4-D and glyphosate-based herbicides on morphofunctional and biochemical markers in Scinax squalirostris tadpoles (Anura, Hylidae).

Understanding the effects of pesticides on non-target organisms is essential to assess the impact of these xenobiotics on the environment, allowing for a more informative and safer usage. The present study sought to evaluate the response of Scinax squalirostris tadpoles when exposed to different concentrations of two herbicides, DEZ® (i.e., dichlorophenoxyacetic acid or 2,4-D) and Roundup® Original (i.e., glyphosate). We collected 140 tadpoles between Gosner's 25 and 34 stages in a preservation area of the South American jelly palm Butia odorata. The animals were separated into eight groups and maintained in aquariums: acclimatization control (17 days), exposure control (24 days), and six exposure groups (7 days), including three concentration groups of each pesticide (4 µg/L, 15 µg/L, and 30 µg/L 2,4-D acid equivalent; 65 µg/L, 250 µg/L, and 500 µg/L glyphosate acid equivalent). Markers of body condition (length, body mass, K and Kn index) and oxidative balance (superoxide dismutase, catalase, glutathione S-transferase, TBARS, and carbonyl proteins) were analyzed. After 24 days (17 days of acclimation plus 7 days of exposure), tadpoles exposed to 15 µg/L of 2,4-D and 65 µg/L of glyphosate grew at higher than expected concentrations. They also had less lipoperoxidation than control tadpoles and higher superoxide dismutase, catalase, and glutathione S-transferase activity, specifically at the highest herbicide concentrations (2,4-D: 30 µg/L; glyphosate: 500 µg/L of glyphosate). Only the highest concentration of 2,4-D determined an increase in the levels of carbonyl proteins, indicating oxidative damage induced. DEZ® required more antioxidant defenses and induced a concentration-dependent answer of carbonylated proteins, suggesting oxidative stress and more toxic potential. These results may help government agencies make more conscious decisions regarding the usage of these chemicals and consider a balance between the conservation of amphibian species and agribusiness economic sustenance.