Ecology & Evolution Seminar Series 2015 - Ingrid Richter
Ecology & Evolution Seminar Series 2015 - Ingrid Richter
Date:
2 April 2015
Time: 12.00 pm
Ingrid Richter presents Molecular
evolution and functional characterisation of tunicate xenobiotic receptors.
Vertebrate pregnane X receptor (PXR, NR1I2), a
ligand-activated nuclear receptor, regulates expression of detoxification
genes. Vertebrate PXR orthologues may adaptively evolve to bind
deleterious/toxic xenobiotics typically encountered by organisms from their
diet. Tunicates (phylum Chordata) are marine filter-feeders that form a sister
clade to the Vertebrata. Genomes of two tunicate taxa, Ciona intestinalis and Botryllus
schlosseri, encode at least two PXR orthologues. The
research outcomes presented in this talk demonstrate that tunicate xenobiotic
receptors may provide a source of sensor elements that have been pre-moulded by
natural selection for detecting bioactive chemicals. Using next-generation sequencing, high intra-taxa genetic diversity was observed within
three tunicate xenobiotic receptor orthologues. These data supported the notion
that tunicate xenobiotic receptors might enhance binding of dietary exogenous
bioactive compounds (e.g. toxins) typically encountered by these organisms.
This provided the foundation for the development of a generic bioassay for
assessing the activity of these biological compounds. Recombinant yeast strains
were developed in which ligand-dependent activation of tunicate xenobiotic
receptors was transduced into easily quantifiable phenotypic changes in the
yeast strains. These tunicate yeast bioassays have the potential for detecting
microalgal biotoxins, bioactive compounds that may provide templates for drug
development and environmental contaminants.