A GC-MS method for the identification and quantification of steroid hormones in Ciona intestinalis ovaries, their relatedness to vertebrate hormones and modulation by Tributyltin (TBT)

In this study, we have validated a gas chromatography-mass spectroscopy (GS-MS) method for the identification and quantification of sex steroid hormone in the ovary of C. intestinalis, determined their relatedness with vertebrates variants and modulation by an endocrine disrupting chemical, tributyltin (TBT). Using this method, we identified and quantified several ovarian steroids in Ciona with high similarity to vertebrate sex steroids and shown that estrone, estradiol-17β, testosterone, pregnenolone, progesterone, cholesterol and corticosterone have identical molecular structure with vertebrate steroids. In addition, exposure of Ciona ovaries to TBT produced modulations (either increased or decreased) of sterols and sex levels. To our knowledge, this is the first time such similarity has been demonstrated in one of the most prevalent modern urochordates, the ascidians. Given that the ascidians represent very simple experiment models for the study of endocrine disruption by environmental contaminants, this method and findings provide excellent models for multiple identification and quantification of sex steroid in biological samples exposed to endocrine-disrupting chemicals and for direct extrapolation of such effects across taxonomic groups and phyla.