Coping with dry spells: Investigating oxidative balance and metabolic responses in the subtropical tree frog Boana pulchella (Hylidae) during dehydration and rehydration exposure.

In the face of climate change, understanding the metabolic responses of vulnerable animals to abiotic stressors like anurans is crucial. Water restriction and subsequent dehydration is a condition that can threaten populations and lead to species decline. This study examines metabolic variations in the subtropical frog Boana pulchella exposed to dehydration resulting in a 40% loss of body water followed by 24 h of rehydration. During dehydration, the scaled mass index decreases, and concentrations of metabolic substrates alter in the brain and liver. The activity of antioxidant enzymes increases in the muscle and heart, emphasizing the importance of catalase in the rehydration period. Glycogenesis increases in the muscle and liver, indicating a strategy to preserve tissue water through glycogen storage. These findings suggest that B. pulchella employs specific metabolic mechanisms to survive exposure to water restriction, highlighting tissue-specific variations in metabolic pathways and antioxidant defenses. These findings contribute to a deeper understanding of anuran adaptation to water stress and emphasize the importance of further research in other species to complement existing knowledge and provide physiological tools to conservation.

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 commercial formulations of herbicides alone and in mixtures on the antioxidant system and body condition parameters in tadpoles of Rhinella icterica (Spix 1824).

Pesticide usage has increased over the last decades, leading to concerns regarding its effects on non-target organisms, especially amphibians. Tadpoles of Rhinella icterica were collected in a pesticide-free place, acclimated in the laboratory (21 days) and exposed (7 days) to three herbicides (20 µg/L atrazine (A); 250 µg/L glyphosate (G); 20 µg/L quinclorac (Q)) and their mixtures. Only 2% mortality was observed over the 28 days of the study. Despite this, significant variations were observed for markers of oxidative balance and body condition when comparing all experimental groups. K and Kn factor showed the lowest values in the group A+G+Q, as well as the activity levels of GST and SOD. In contrast to this, the CAT activity was higher in the same group (A+G+Q). The mixture of the three herbicides proved to be more harmful, which points to the need for more restrictive laws for the use of mixed herbicides.

Biochemical and body condition markers in Rhinella icterica tadpoles exposed to atrazine, glyphosate, and quinclorac based herbicides in ecologically relevant concentrations.

Amphibians have suffered population decline due to several factors, including exposure to pesticides. In the south of Brazil, rice cultivations use herbicides based on atrazine, glyphosate and quinclorac as the commercial formulations Primoleo®, Roundup® and Facet®, respectively. Rhinella icterica was chosen to evaluate oxidative balance markers and body condition after exposure to three concentrations of herbicides (10, 20 and 40 µg/L of atrazine and quinclorac; 100, 250 and 500 µg/L of glyphosate). These xenobiotics, regardless of the concentrations used, accelerated the development process of animals and seemed to act as modulators of development. We observed no significant variations for any of the oxidative balance markers studied (superoxide dismutase, catalase, TBARS and carbonylated proteins); however, we cannot rule out that other antioxidant system components prevent oxidative stress. In general, atrazine and glyphosate accelerated the development of tadpoles, and quinclorac retards this process, which could impact the survival of these animals.