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Identification of Gender-specific Transcripts by Microarray in Gonad Tissue of Larval and Juvenile Xenopus tropicalis
Citation:
HASELMAN, J., A. W. OLMSTEAD, AND S. J. DEGITZ. Identification of Gender-specific Transcripts by Microarray in Gonad Tissue of Larval and Juvenile Xenopus tropicalis. Presented at International Symposium on Amphibian Endocrinology and Neurobiology (ISAREN), Ann Arbor, MI, July 11 - 13, 2011.
Impact/Purpose:
Examination of these expression profiles in gonad tissue influenced by xenobiotic exposure will provide insight into molecular mechanisms and processes leading to amphibian gonadal intersex and functional sex-reversal.
Description:
Amphibian model species Xenopus tropicalis is currently being utilized by EPA in the development of a standardized in vivo reproductive toxicity assay. Perturbations to the hypothalamic-pituitary-gonadal axis from exposure to endocrine disrupting compounds during larval development have been shown to induce abnormal gonad differentiation resulting in either functional sex-reversal or intersex conditions. In an effort to develop a gene expression-based diagnostic tool we characterized male and female gonadal transcriptomes by microarray. Gonad tissues were harvested from Niewkoop and Faber (NF) stage 58 larvae, NF 66 froglets, one week and two week old juveniles. Individual animals were genotyped to confirm genetic sex and gonad RNA was extracted and pooled according to developmental stage and gender. Initial data analyses were performed with Agilent GeneSpring GX 11 and gene enrichment and ontology analyses were carried out with gender-specific gene lists using DAVID Bioinformatics Resources 6.7. Results confirm significant differences (p= 0.05 and differential expression = 10-fold) in expression in two week old juveniles between ovary and testis tissues of several enzymes involved in steroid hormone biosynthesis. Other ovary-specific profiles include oocyte-specific proteins and several proteins involved in progesterone mediated oocyte maturation and oocyte meiosis. Additional testis-specific profiles include a Leydig cell-specific peptide and hormone receptors. These data allow for further investigation of molecular interactions responsible for gonad differentiation and will provide candidate genes for use as expression-based biomarkers of gonad maturation. Examination of these expression profiles in gonad tissue influenced by xenobiotic exposure will provide insight into molecular mechanisms and processes leading to amphibian gonadal intersex and functional sex-reversal.