Atrazine exposure elicits copy number alterations in the zebrafish genome

Abstract

Atrazine is an agricultural herbicide used throughout the Midwestern United States that frequently contaminates potable water supplies resulting in human exposure. Using the zebrafish model system, an embryonic atrazine exposure was previously reported to decrease spawning rates with an increase in progesterone and ovarian follicular atresia in adult females. In addition, alterations in genes associated with distinct molecular pathways of the endocrine system were observed in brain and gonad tissue of the adult females and males. Current hypotheses for mechanistic changes in the developmental origins of health and disease include genetic (e.g., copy number alterations) or epigenetic (e.g., DNA methylation) mechanisms. As such, in the current study we investigated whether an atrazine exposure would generate copy number alterations (CNAs) in the zebrafish genome. A zebrafish fibroblast cell line was used to limit detection to CNAs caused by the chemical exposure. First, cells were exposed to a range of atrazine concentrations and a crystal violet assay was completed, showing confluency decreased by ∼60% at 46.3 μM. Cells were then exposed to 0, 0.463, 4.63, or 46.3 μM atrazine and array comparative genomic hybridization completed. Results showed 34, 21, and 44 CNAs in the 0.463, 4.63, and 46.3μM treatments, respectively. Furthermore, CNAs were associated with previously reported gene expression alterations in adult male and female zebrafish. This study demonstrates that atrazine exposure can generate CNAs that are linked to gene expression alterations observed in adult zebrafish exposed to atrazine during embryogenesis providing a mechanism of the developmental origins of atrazine endocrine disruption.

Seasonal variation of chloro-s-triazines in the Hartbeespoort Dam catchment, South Africa

“…Atrazine has been proven to be an endocrine disruptor in many species (Freeman et al, 2011;Rohr and McCoy, 2010). However, numerous studies of effects of atrazine on the reproductive, nervous and immune systems on humans and animals have produced contradicting results with lack of consistency (Rohr and McCoy, 2010;Solomon et al, 2008;Wirbisky and Freeman, 2017). Atrazine has been observed to cause gene alterations that lead to endocrine disruption in zebrafish, inhibition of ovary growth in crabs, altering sex ratios in crayfish and frogs as well as demusculinising male gonads in fish, amphibians, reptiles and mammals (Hayes et al, 2011;Loughlin et al, 2016;Silveyra et al, 2017;Wirbisky and Freeman, 2017).…”

Exposure to the Heavy-Metal Lead Induces DNA Copy Number Alterations in Zebrafish Cells

“…A crystal violet cell confluency assay was completed following similar parameters as previously described. , Briefly, cells were harvested from cell culture flasks and cell concentration determined using a Z1 Coulter particle counter (Beckman Coulter). A 96-well plate was seeded with 14,000 cells per well.…”

“…Features of array images were extracted using Agilent Feature Extraction version 11.5 (Agilent Technologies, Santa Clara, CA). Microarray analysis was completed following MIAME guidelines using the aberration detection method 2 (ADM2) algorithm in Agilent Genomic Workbench 7.0 (Agilent Technologies, Santa Clara, CA) similar to as described in Wirbisky and Freeman . Calls were then converted to reflect genomic locations in the latest zebrafish genome build (GRCz11/danRer11) using the UCSC Genome Browser converter tool.…”

“…A few studies have now started to investigate the role of chemical exposure in generating CNAs as a genetic mechanism of toxicity. Exposure to certain chemicals including aphidicolin (APH), hydroxiurea (HU), ethylmethanesulfonate (EMS), cytosine β- d -arabinofuranoside (Ara-C), and atrazine resulted in CNAs in human, mouse, or zebrafish cells. − Environmental epidemiological studies are also beginning to assess the contribution of asbestos exposure in the presence of CNAs in the human genome and the relationship between the most common CNAs in autism spectrum disorder and the concentration of persistent organic pollutants in post-mortem brain samples of individuals with autism spectrum disorder . However, there is a lack of studies assessing influences of most environmental chemical contaminants including the heavy-metal neurotoxicant lead (Pb), in generating de novo CNAs as a genetic mechanism leading to the associated adverse health outcomes.…”

Adsorption of Atrazine by Biochars Produced From Byproducts of the Wood Industry

“…In nature, research on rats shows problems in the morphology of the male genital system due to contact with atrazine, such as increased estrogen and decreased progesterone levels (Victor-Costa et al, 2010). In addition, several problems have been described in other animals, such as lobsters (Mac Loughlin et al, 2016), fish (Wirbisky & Freeman, 2017), and amphibians (Gonçalves et al, 2017).…”