07/10/2026 – SEMINÁRIO DE DADOS (Mestrado) – EDUARDA RIBEIRO KOEHLER

SEMINÁRIO DE DADOS (Mestrado)

EDUARDA RIBEIRO KOEHLER 

Oxidative Stress and mariner Transposable Element Mobilization in Drosophila simulans

Orientador: Dr. Élgion Lúcio da Silva Loreto

Avaliadora: Dra. Maríndia Deprá

07 de outubro de 2026 (quarta-feira)

12h

Apresentação somente na modalidade remota

Sala virtual: https://conferenciaweb.rnp.br/ufrgs/ppgbm

Abstract

Transposable elements (TEs), also known as “jumping genes,” are DNA sequences capable of moving to different genomic locations and constitute a substantial fraction of eukaryotic genomes. Their mobilization may contribute to genomic instability, changes in gene expression, cellular aging and disease, potentially affecting organismal fitness. Although several studies have associated TE mobilization with stressful conditions, it remains unclear whether this response represents a general consequence of cellular stress or depends on the specific type of stressor and the damage it induces. The mariner TE provides an appropriate model for investigating this relationship because its somatic excision (SE) can be phenotypically monitored in Drosophila simulans carrying the wpch mutation through the formation of mosaic eye. In this study, we investigated whether oxidative stress – characterized by an imbalance between the formation of reactive species and free radicals and the defense capacity of antioxidant and repair systems, potentially causing damage to biomolecules such as DNA – modulates mariner activity and whether different oxidative stressors induce distinct responses. Male D. simulans wpch were exposed to four chemical agents with different mechanisms of action and oxidative and/or genotoxic potential: hydrogen peroxide (H2O2), paraquat (PQ), cyclophosphamide (CP), and ethidium bromide (EtBr). Acute and chronic exposure protocols were used to investigate biochemical, physiological and genomic responses. Oxidative stress was assessed through total reactive species production and the activities of the antioxidant enzymes catalase, superoxide dismutase, and glutathione S-transferase. Longevity was evaluated using a survival curve as a physiological outcome, while mariner activity was assessed through the frequency of somatic excision, observed through the mosaic phenotype in the flies’ eyes. All treatments significantly increased reactive species production and altered antioxidant enzyme activities, confirming the induction of oxidative stress. In addition, all exposed groups showed significantly reduced longevity compared with the control group, demonstrating that the treatments induced relevant physiological effects. Despite these common responses, a significant increase in mariner somatic excision was observed exclusively in EtBr exposure. Therefore, the induction of oxidative stress alone was not sufficient to promote mariner mobilization. These results indicate that the activity of the mariner element is not universally influenced by oxidative stress and suggest that the mobilization of transposable elements is not universal, potentially depending on the specific characteristics of the stressor and the molecular mechanisms resulting from the consequent cellular and genomic damage.