Efeitos da vizinhança na polinização: análise em múltiplos contextos de comunidade

Abstract

Acetaminophen (ACE) is one of the most widely used analgesics and non-steroidal anti- inflammatory drugs in the world, and is often found in aquatic environments, where it can act as an endocrine disruptor on non-target species such as fish. Chronic exposure to toxic substances can cause epigenetic changes by decreasing glutathione (GSH) levels and hypomethylating DNA, leading to possible transgenerational effects. The aim of this study was to analyze the effects of exposure to different concentrations of acetaminophen on gametogenesis, reproductive biology and gonadal DNA methylation of Danio rerio in the parental generation and in their F1 and F2 offspring. Gametogenesis was analyzed by histology, morphometry, cell proliferation and apoptosis. This study also evaluated levels of sex steroids and prostaglandin E2 (PGE2), gene expression for sex steroids and PGE2 receptors, fertilization rate, semen quality, amount of methylated DNA and expression of enzymes that methylate and demethylate DNA. In females of the parental generation (F0), exposure to 5 and 50 μg/L of ACE induced larger and more abundant vitellogenic follicles and increased follicular atresia. In these treatments, males showed a lower proportion and proliferation of undifferentiated spermatogonia, and a higher proportion of TUNEL-positive differentiated spermatogonia, spermatids and spermatozoa, resulting in lower sperm production. ACE increased 17β-estradiol (E2) and reduced 11-ketotestosterone (11-KT) levels in testes, while only E2 increased in ovaries. In both sexes, gonadal PGE2 levels were reduced. ACE at 50 μg/L induced an increase an androgen, estrogen and PGE2 receptors gene expression in the ovaries, and reduced expression in the testes. The results also showed lower egg production and fertilization rate after 28 days of exposure with reduced sperm quality. The treatment resulted in a reduced GSH levels and expression of DNA-methylating enzymes (DNMTs), increased in DNA- demethylating enzymes (TETs), which led to global DNA hypomethylation in the F0 testes and ovaries. The F1 and F2 ovaries derived from the F0 generation exposed to 50 μg/L of ACE, showed a lower concentration of E2 and less vitellogenic follicles, leding to a reduction in eggs released. The F1 testes of progenitors also exposed to 50 μg/L showed a reduction in 11-KT, less abundant sperm and lower semen quality. The F2 males did not show reproductive changes with the F0 treatment to ACE. These results demonstrated that ACE impairs the reproductive performance of zebrafish, affecting multiple reproductive parameters, which may be caused by the synergistic action of sex steroid imbalance, with a reduction in PGE2 and its receptors. Furthermore, chronic exposure to ACE may led to transgenerational effects by inducing epigenetic changes in F0 and reducing the reproductive capacity of F1 and F2 zebrafish.