Global Gene Expression Analysis Reveals Dynamic and Developmental Stage–Dependent Enrichment of Lead-Induced Neurological Gene Alterations

Abstract

BackgroundThe underlying genetic mechanisms specific to subtle neurological alterations associated with environmental lead (Pb) exposures have not been clearly elucidated.ObjectivesThe goal of this study was to identify novel gene targets and the underlying genetic mechanisms associated with developmental Pb neurotoxicity.MethodsWe first exposed zebrafish embryos to a range of Pb concentrations throughout early development to establish relative toxicity. Using the data from that experiment, we exposed another group of zebrafish embryos to a sublethal dose of Pb (100 ppb) immediately after fertilization through 72 or 120 hr postfertilization (hpf). Global gene expression was then analyzed for molecular pathways and gene ontology enrichment, and Western blot analysis was performed to investigate the translation of gene expression changes to protein levels.ResultsAfter 72 hpf, we identified 231 probes representing 90 nonredundant genes with well-established function or orthology to human genes as being altered by Pb exposure. This gene set was both confirmatory and novel in nature and was highly enriched for neurological development, function, and disease. Moreover, gene changes at this time point were correlated to altered protein levels. Alternatively, the gene set at 120 hpf did not share association with neurological development.ConclusionsGlobal gene expression alterations associated with developmental Pb exposure were dynamic and dependent on developmental stage. Gene expression alterations at the 72-hpf time point were highly enriched with genes and molecular pathways associated with neurological development and disease. Moreover, we identified a number of novel targets for future exploration into their role in the genetic mechanisms underlying Pb-induced neurological alterations.

Water Contaminated With the Herbicide Atrazine: Alteration of Cancer Associated Tumor Protein D52-like 1 (tpd52l1) Gene Using the Zebrafish Model

“…Forward and reverse primers for the target genes were designed using the Primer3 website (see Table 1). qPCR was conducted following similar methods as previously done in our laboratory (Peterson et al, 2010). The qPCR analysis used SSoAdvanced SYBR Green Supermix (Biorad) to determine gene expression levels (gene of interest/β-actin).…”

“…The qPCR analysis used SSoAdvanced SYBR Green Supermix (Biorad) to determine gene expression levels (gene of interest/β-actin). The cycling parameters for the qPCR were: 3 minute incubation phase at 95°C, 40 cycles of 95°C for 10 s, 60°C for 30 s and 72°C for 30 s and are further explained in a previous study (Wirbisky et al, 2015;Peterson et al, 2010).…”

“…A least significant difference (LSD) post hoc test was performed if significance was met for the ANOVA test to establish when sets of data were different from each other, similar to other studies in our laboratory (Peterson et al, 2010;Wirbisky et al, 2015;Wirbisky et al, 2016). expression (p = 0.3040; see Figure 4C).…”

Zebrafish as a Model for Developmental Neurotoxicity Assessment: The Application of the Zebrafish in Defining the Effects of Arsenic, Methylmercury, or Lead on Early Neurodevelopment

“…Low concentrations tested in the Pb exposure studies described below show that the zebrafish is indeed a very sensitive in vivo test model for DNT assessment. For example, Peterson et al [128] evaluated global gene expression changes in developing zebrafish in response to a low-dose Pb exposure. Microarray analysis was performed with embryos treated with 100 ppb (≈0.5 µM) Pb through the end of embryogenesis, resulting in significant expression alterations of 55 genes engaged in processes related to nervous system development/functioning and neurological diseases [128].…”

“…For example, Peterson et al [128] evaluated global gene expression changes in developing zebrafish in response to a low-dose Pb exposure. Microarray analysis was performed with embryos treated with 100 ppb (≈0.5 µM) Pb through the end of embryogenesis, resulting in significant expression alterations of 55 genes engaged in processes related to nervous system development/functioning and neurological diseases [128]. Western blot analysis revealed significant changes in expression of several target proteins including metallothionein-2, FRY-like, and reelin [128].…”