Detection of marine microalgal biotoxins using bioassays based on functional expression of tunicate xenobiotic receptors in yeast

作者：Richter Ingrid^*; Fidler Andrew E

来源：Toxicon, 2015, 95: 13-22.

DOI：10.1016/j.toxicon.2014.12.011

• Ciona intestinalis
• Botryllus schlosseri
• Pregnane X receptor
• Saccharomyces cerevisiae
• Marine biotoxins
• Bioassay

Marine microalgae can produce biotoxins that cause widespread poisoning in marine ecosystems and may also affect human health. While established microalgal biotoxins are detectable using chemical methods, a need remains for robust, inexpensive bioassays. Ligand-binding domains (LBDs) from a tunicate nuclear receptor, VDR/PXR alpha, which is orthologous to both the vertebrate pregnane X receptor (PXR) and the vitamin D receptor (VDR), can be activated by microalgal biotoxins when expressed in mammalian cell lines. Building on this observation, we developed a generic recombinant yeast bioassay platform that expresses chimeric proteins containing tunicate VDR/PXR alpha LBDs which mediate ligand-dependent transcription of a reporter gene (lacZ) encoding an easily assayed enzyme (beta-galactosidase). Recombinant yeast strains expressing VDR/PXR alpha LBDs from two tunicate species. Ciona intestinalis and Botryllus schlosseri, were exposed to both synthetic and natural toxins. Structurally simple synthetic chemicals (n-butyl-p-aminobenzoate, carbamazepine, p-aminobenzoic acid, and bisphenol-A) generated EC50 values in the mu M range, while more structurally complex marine biotoxins (okadaic acid, pectenotoxin-11, and portimine) activated the assays in the nM range. Given the large number of tunicate species, we propose that tunicate VDR/PXR LBDs may be used as 'sensor elements' in similar yeast-based high-throughput bioassays for detection of established microalgal biotoxins and uncharacterised marine bioactive compounds.

• 出版日期2015-3