Gene expression endpoints following chronic waterborne copper exposure in a genomic model organism, the zebrafish, Danio rerio

Paul M. Craig, Christer Hogstrand, Chris M. Wood, Grant B. McClelland

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

Although copper (Cu) is an essential micronutrient for all organisms, in excess, waterborne Cu poses a significant threat to fish from the cellular to population level. We examined the physiological and gene expression endpoints that chronic waterborne Cu exposure (21 d) imposes on soft-water acclimated zebrafish at two environmentally relevant concentrations: 8 μg/l (moderate) and 15 μg/l (high). Using a 16,730 65-mer oligonucleotide customized zebrafish microarray chip related to metal metabolism and toxicity to assess the transcriptomic response, we found that 573 genes in the liver responded significantly to Cu exposure. These clustered into three distinct patterns of expression. There was distinct upregulation of a majority of these genes under moderate Cu exposure and a significant downregulation under high Cu exposure. Microarray results were validated by qPCR of eight genes; two genes, metallothionein 2 (mt2) and Na+-K+-ATPase 1a1 (atp1a1), displayed increased expression under both Cu exposures, indicative of potential genetic endpoints of Cu toxicity, whereas the remaining six genes demonstrated opposing effects at each Cu exposure. Na+-K+-ATPase enzyme activity decreased during Cu exposure, which may be linked to Cu's competitive effects with Na+. Whole body cortisol levels were significantly increased in Cu-exposed fish, which prompted an analysis of the promoter region of all significantly regulated genes for glucocorticoid (GRE) and metal (MRE) response elements to dissociate metal- and stress-specific gene responses. Of the genes significantly regulated, 30% contained only a GRE sequence, whereas 2.5% contained only a consensus MRE. We conclude that the indirect effects of Cu exposure regulate gene expression to a much greater degree than the direct effects.

Original languageEnglish
Pages (from-to)23-33
Number of pages11
JournalPhysiological Genomics
Volume40
Issue number1
DOIs
StatePublished - Jan 1 2009

Fingerprint

Zebrafish
Copper
Gene Expression
Genes
Metals
Fishes
Metallothionein
Micronutrients
Response Elements
Genetic Promoter Regions
Oligonucleotides
Glucocorticoids
Hydrocortisone
Up-Regulation
Down-Regulation
Water
Liver
Enzymes
Population

Keywords

  • Cortisol
  • Glucocorticoid response element
  • Metal response element
  • Microarray

ASJC Scopus subject areas

  • Physiology
  • Genetics

Cite this

Gene expression endpoints following chronic waterborne copper exposure in a genomic model organism, the zebrafish, Danio rerio. / Craig, Paul M.; Hogstrand, Christer; Wood, Chris M.; McClelland, Grant B.

In: Physiological Genomics, Vol. 40, No. 1, 01.01.2009, p. 23-33.

Research output: Contribution to journalArticle

Craig, Paul M. ; Hogstrand, Christer ; Wood, Chris M. ; McClelland, Grant B. / Gene expression endpoints following chronic waterborne copper exposure in a genomic model organism, the zebrafish, Danio rerio. In: Physiological Genomics. 2009 ; Vol. 40, No. 1. pp. 23-33.
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