Different transcriptional responses of heat shock protein 70/90 in the marine diatom Ditylum brightwellii exposed to metal compounds and endocrine-disrupting chemicals

• Published in: Chemosphere (Oxford) 2013-07, Vol.92 (5), p.535-543
• Main Authors: Guo, R., Lee, M.-A., Ki, J.-S.
• Format: Article
• Language: English
• Subjects: Algal Proteins - chemistry; Algal Proteins - genetics; Amino Acid Sequence; Animal, plant and microbial ecology; Applied ecology; Base Sequence; Biological and medical sciences; chlorides; copper sulfate; DbHSP70; DbHSP90; Diatom; Diatoms - chemistry; Diatoms - genetics; Diatoms - physiology; Ditylum; Ditylum brightwellii; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on plants and fungi; endocrine-disrupting chemicals; environmental hazards; Fundamental and applied biological sciences. Psychology; Gene expression; gene expression regulation; genes; heat shock proteins; HSP70 Heat-Shock Proteins - chemistry; HSP70 Heat-Shock Proteins - genetics; HSP90 Heat-Shock Proteins - chemistry; HSP90 Heat-Shock Proteins - genetics; Metal compounds; Metals - toxicity; Molecular Sequence Data; Phylogeny; pollutants; quantitative polymerase chain reaction; Stress, Physiological; Temperature; thermal stress; toxicity; toxicology; transcription (genetics); Transcriptional Activation; Water Pollutants, Chemical - toxicity
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2013.03.052

•Toxicogenomic responses of HSP70/90 in marine diatom Ditylum brightwellii.•DbHSP70/90 contained conserved HSP family motifs, but different C-terminus motifs.•DbHSP70/90 were differentially involved in defense responses to environmental stress.•Metal toxicity was specifically affected by the conjugated anion in metal compounds.•DbHSP70/90 were not induced by certain organic pollutants, including EDCs. Environmental hazard assessments using diatoms have been well documented; however, their molecular toxicology has not been sufficiently studied. In this study, we characterized heat shock protein (HSP) 70/90 of the diatom Ditylum brightwellii (Db) and evaluated their transcriptional profiles in response to various environmental stresses (e.g., thermal shocks and metal and non-metal pollutants). Putative DbHSP70 (658aa, 71.7kDa) and DbHSP90 (707aa, 80.2kDa) proteins had conserved HSP family motifs but different C-terminus motifs, that is, “EEVD” in DbHSP70 and “MEEVD” in DbHSP90. Phylogenetic analyses of both proteins showed that D. brightwellii was well clustered with other diatoms. Real-time PCR analysis showed that thermal stress considerably upregulated DbHSP70 and DbHSP90. As for chemical pollutants, DbHSP70 greatly responded to CuSO4 and NiSO4 exposure, but not CuCl2 or NiCl2. However, DbHSP90 was significantly upregulated by all the metal compounds tested (CuSO4, NiSO4, CuCl2, and NiCl2). Strikingly, the expression of both genes was not induced by the organic pollutants tested, such as endocrine-disrupting chemicals. These data suggest that DbHSP70 and DbHSP90 are differentially involved in the defense response against various environmental stressors. Moreover, metal toxicity may be specifically affected by the conjugated anion in the metal compounds (e.g., SO42- and Cl−).