Delayed effects of permethrin exposure on personality traits and (epi)genetic associated mechanisms in the mangrove rivulus, Kryptolebias marmoratus

Details

Supervisors

Frédéric Silvestre

Faculty

Faculté des sciences

Degree label

Master [120] en biologie des organismes et écologie, à finalité approfondie

Abstract

While early life stages (ELS) constitute a crucial period for behavioural individualities’ establishment and maintenance, they are also recognized to be sensitive to neurotoxicants such as permethrin (PM). PM neurotoxicity is particularly harmful to fish species and is sometimes manifested as neurobehavioural changes. Yet, the underlying epigenetic contribution to PM persistent effects on behaviour and personality’s ontogeny on fishes, remain enigmatic. The main scope of this review is to investigate PM-related behavioural delayed effects on the self-fertilizing Kryptolebias marmoratus, and to identify possible epigenetic related molecular processes. To achieve this goal, we subjected mangrove killifish larvae to a one-week exposure period (from 0 to 7 days post-hatching) under three distinct conditions: absence of PM (0µg/L), low concentration (5 µg/L), and high concentration (200 µg/L). We first explored the impact of exposure on phenotypic attributes encompassing behaviour through the implementation of a shelter test. Subsequently, we evaluated the repercussions on a molecular scale, specifically in terms of relative gene expression and the methylation status of select genes, mainly behaviour related. After a larval exposure to a high PM concentration, adults’ mangrove rivulus exposed to the high PM concentration (200 µg/L), significantly exhibited repeatable behaviours. No other consistent phenotypical differences, either behaviour or life history-trait related endpoints, have been detected. Furthermore, no effect on DNA methylation or relative expression of genes, either related to neurological functions (Nipbl, Mecp2) or involved in DNA methylation (Dnmt3a), has been highlighted. However, a slight tendency of growth compensation might exist following a one-week-200 µg/L permethrin exposure, leading to recovery from the observed decreases in growth, length, and weight in 7-day-old post-hatching larvae. The non-persistent larval neurobehavioural alterations, tend also to demonstrate recovery mechanisms that could be based on neurogenesis. Overall, this study suggests that PM might trigger the emergence of behavioural individualities (repeatability) on adults Kryptolebias marmoratus. Moreover, it shows the high resilience capacity of this neotropical fish model, both at the neurobehavioural and morphological levels, following exposure to a neurotoxicant.