Molecular markers of ecotoxicological interest in the rainbowfish Melanotaenia fluviatilis

Ponza, P 2006, Molecular markers of ecotoxicological interest in the rainbowfish Melanotaenia fluviatilis, Doctor of Philosophy (PhD), Applied Sciences, RMIT University.


Document type: Thesis
Collection: Theses

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Title Molecular markers of ecotoxicological interest in the rainbowfish Melanotaenia fluviatilis
Author(s) Ponza, P
Year 2006
Abstract The Crimson-spotted rainbowfish (Melanotaenia fluviatilis) from the Murray-Darling basin of Australia is a common indicator species in Australian ecotoxicology. Biochemical changes have been investigated in this species, but not molecular markers of ecotoxicological interest. In this study genes of M. fluviatilis were isolated using a cDNA library and sequences analysed. Of 345 randomly selected clones, 94 shared similarity with 26 different genes in other organisms in public databases. Amongst these, reproductive genes coding for vitellogenin, retinol binding protein, sialyltransferase and zona pellucida protein were considered of interest in ecotoxicology. The vitellogenin gene was selected for study as it has been widely used as a molecular marker of exposure to 17â-estradiol (E2) in teleosts. Gene expression was examined via northern blot, RT-PCR and Real-Time PCR relative t o the housekeeping gene (18S rRNA). The expression of vitellogenin mRNA was observed at 12 hours post-exposure, peaked at 48 hours according to northern blot analysis; and cleared within 4 days, partly consistent with RT-PCR. However, Real-time PCR yielded an inconclusive result, probably due to differences between pooled and individual samples. Vitellogenin in blood plasma was confirmed by western blot, found to be significantly increased and retained in the plasma in fish treated with E2 compared to controls. It was concluded that vitellogenin mRNA is a molecular marker of exposure to 17â-estradiol in the rainbowfish, and could potentially be used as a marker of exposure to environmental estrogenic chemicals. Further investigations of the expression of genes in the cDNA library, could establish other molecular markers of ecotoxicological interest in M. fluviatilis.
Degree Doctor of Philosophy (PhD)
Institution RMIT University
School, Department or Centre Applied Sciences
Keyword(s) Murray-Darling Basin -- Environmental conditions
Water Pollution -- Australia -- Measurement
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