Mutagenic assessment of Lithobates catesbeianus tadpoles exposed to the 2,4-D herbicide in a simulated realistic scenario

Abstract

The aim of the current study is to assess possible erythrocyte mutagenic effects on Lithobates catesbeianus tadpoles exposed to water contaminated with 2,4-D. In order to do so, tadpoles were exposed to a predictive and environmentally relevant herbicide concentration (1.97 mg/L), which is likely to be found in lentic environments formed by superficial water runoffs in pasture areas where the herbicide was applied. The micronucleus test, as well as tests for other nuclear abnormalities, was conducted after 3, 5, and 9 days of exposure (d.e.). Changes in the biomass and mouth-cloaca length or interference in the larval development of the animals (in the three evaluated times) were not recorded. However, tadpoles exposed to 2,4-D showed the highest total number of nuclear abnormalities, as well as the highest frequency of binucleated erythrocytes and kidney-shaped nuclei (shortly after 3 d.e.). The micronucleus frequency was also higher in animals exposed to 2,4-D (in the 3rd, 5th, and 9th d.e.), as well as the frequency of binucleated cells (3rd, 5th, and 9th d.e.) presenting notched (9th d.e.) and blebbled (9th d.e.) nuclei in comparison to those of the control, after 5 and 9 days of exposure. Therefore, the current study is a pioneer in showing that 2,4-D has a mutagenic effect on L. catesbeianus tadpoles, even at low concentrations (environmentally relevant) and for a short period of time, a fact that may lead to direct losses in anuran populations living in areas adjacent to those subjected to 2,4-D herbicide application.

Acute Toxicity and Sublethal Effects Caused by a Commercial Herbicide Formulated with 2,4-D on Physalaemus albonotatus Tadpoles

“…Physalaemus albonotatus tadpoles exposed to 43.75, 87.5, 175, and 262.5 mg/L of 2,4-D Amina Zamba® showed no significant differences in body sizes (SVL, TL, and BW) compared to control. These results are in concordance with those of Mesak et al (2018), and demonstrate that the body size cannot be directly related to the dose-dependent effect of the herbicide analyzed.…”

Habitat differences affect the nuclear morphology of the erythrocytes and the hepatic melanin in Leptodactylus fuscus (Anura) in the Brazilian Cerrado savanna

“…As pesticides are applied during the planting of crops, the failure to detect these substances in the water samples may re ect the diluting effects of the rainfall in the region, which may wash the substances out of the soil over time. A number of experimental studies have also demonstrated the formation of MNs in larval anurans in response to exposure to agrochemicals (Mesak et al 2018 In the present study, a higher frequency of ENAs was also found in the specimens from the soybean plantation. Although the formation of these anomalies is not fully understood (Benvindo-Souza et al 2020), it does appear to re ect adverse reactions in the cells or control mechanisms used to eliminate cells with damaged DNA (Fijan 2002).…”

“…In addition to micronuclei, other erythrocyte nuclear abnormalities (ENAs) have been associated with the processes of cell division and death (Pollo et al 2015). These abnormalities include lobed and notched nuclei, and binucleated cells (Pollo et al 2015;Pérez-Iglesias et al 2016;Mesak et al 2018).…”