Individuals of the fish Lithognathus mormyrus were exposed to a series of pollutants including: benzo[a]pyrene, pp-DDE, Aroclor 1254, perfluorooctanoic acid, tributyl-tin chloride, lindane, estradiol, 4-nonylphenol, methyl mercury chloride, and cadmium chloride. Five mixtures of the pollutants were injected. Each mixture included one to three compounds. A microarray was constructed using 4608 L. mormyrus hepatic cDNAs cloned from the pollutant-exposed fish. Most clones (4456) were sequenced and assembled into 1494 annotated unique clones. The constructed microarray was used to identify changes in hepatic gene expression profile on exposure to cadmium administered to the fish by feeding or injections. Thirty-one unique clones showed altered expression levels on exposure to cadmium. Prominently differentially expressed genes included elastase 4, carboxypeptidase B, trypsinogen, perforin, complement C31, cytochrome P450 2K5, ceruloplasmin, carboxyl ester lipase, and metallothionein. Twelve sequences have no available annotation. Most genes (23) were downregulated and hypothesized to be affected by general toxicity due to the intensive cadmium exposure regime. The concept of an operational multigene cDNA microarray, aimed at routine and fast biomonitoring of multiple environmental threats, is outlined and the cadmium exposure experiment has been used to demonstrate functional and methodological aspects of the biomonitoring tool. The components of the outlined system include: (1) spotted array, composed of both pollution-affected and constitutively expressed genes, the latter are used for normalization; (2) standard, repeatable labeling procedure of a reference transcript population; and (3) biomarker indices derived from the profile of expression ratio across the pollution-affected genes, between the field-sampled transcript populations and the reference.
Bibliographical noteFunding Information:
The study was supported by the EU projects GENIPOL (EVK3-CT-2001-00057) and MARINEGENOMICS EUROPE (Contract 505403). M.A. was a recipient of the Yohai Ben-Nun and Rieger scholarships. Efrat Shoham-Frider from the IOLR is thanked for the provision of the methyl mercury. The excellent animal care of Maria Sigal is appreciated. Dr. Miriam Kott Gutkowski from the Hebrew University of Jerusalem and Drs. Ofer Shenker and Vered Friedman from the Technion-Israel Institute of Technology in Haifa are thanked for provision of slide-related services.
- Lithognathus mormyrus
- cDNA microarray
ASJC Scopus subject areas
- Aquatic Science