Differential GFP expression patterns induced by different heavy metals in Tg(hsp70:gfp) transgenic medaka (Oryzias latipes)

Mar Biotechnol (NY). 2015 Jun;17(3):317-27. doi: 10.1007/s10126-015-9620-5. Epub 2015 Feb 5.

Abstract

Heat shock protein 70 (Hsp70) is one of the most widely used biomarker for monitoring environment perturbations in biological systems. To facilitate the analysis of hsp70 expression as a biomarker, we generated a Tg(hsp70:gfp) transgenic medaka line in which green fluorescence protein (GFP) reporter gene was driven by the medaka hsp70 promoter. Here, we characterized Tg(hsp70:gfp) medaka for inducible GFP expression by seven environment-relevant heavy metals, including mercury, arsenic, lead, cadmium, copper, chromium, and zinc. We found that four of them (mercury, arsenic, lead, and cadmium) induced GFP expression in multiple and different organs. In general, the liver, kidney, gut, and skin are among the most frequent organs to show induced GFP expression. In contrast, no detectable GFP induction was observed to copper, chromium, or zinc, indicating that the transgenic line was not responsive to all heavy metals. RT-qPCR determination of hsp70 mRNA showed similar induction and non-induction by these metals, which also correlated with the levels of metal uptake in medaka exposed to these metals. Our observations suggested that these heavy metals have different mechanisms of toxicity and/or differential bioaccumulation in various organs; different patterns of GFP expression induced by different metals may be used to determine or exclude metals in water samples tested. Furthermore, we also tested several non-metal toxicants such as bisphenol A, 2,3,7,8-tetrachlorodibenzo-p-dioxin, 4-introphenol, and lindane; none of them induced significant GFP expression in Tg(hsp70:gfp) medaka, further suggesting that the inducibility of Tg(hsp70:gfp) for GFP expression is specific to a subset of heavy metals.

MeSH terms

  • Animals
  • Animals, Genetically Modified
  • Benzhydryl Compounds / toxicity
  • Female
  • Fish Proteins / agonists
  • Fish Proteins / genetics*
  • Fish Proteins / metabolism
  • Gene Expression Regulation
  • Genes, Reporter
  • Green Fluorescent Proteins / agonists
  • Green Fluorescent Proteins / genetics*
  • Green Fluorescent Proteins / metabolism
  • HSP70 Heat-Shock Proteins / agonists
  • HSP70 Heat-Shock Proteins / genetics*
  • HSP70 Heat-Shock Proteins / metabolism
  • Hexachlorocyclohexane / toxicity
  • Intestinal Mucosa / metabolism
  • Intestines / drug effects
  • Kidney / drug effects
  • Kidney / metabolism
  • Liver / drug effects
  • Liver / metabolism
  • Male
  • Metals, Heavy / toxicity*
  • Nitrophenols / toxicity
  • Oryzias / genetics*
  • Oryzias / metabolism
  • Phenols / toxicity
  • Polychlorinated Dibenzodioxins / toxicity
  • Promoter Regions, Genetic
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Skin / drug effects
  • Skin / metabolism
  • Water Pollutants, Chemical / toxicity*

Substances

  • Benzhydryl Compounds
  • Fish Proteins
  • HSP70 Heat-Shock Proteins
  • Metals, Heavy
  • Nitrophenols
  • Phenols
  • Polychlorinated Dibenzodioxins
  • RNA, Messenger
  • Recombinant Fusion Proteins
  • Water Pollutants, Chemical
  • Green Fluorescent Proteins
  • Hexachlorocyclohexane
  • bisphenol A
  • 4-nitrophenol