Expression of the estrogen receptor gene across the life cycle in the polychaete, Capitella teleta

This dataset contains gene expression data for the estrogen receptor (ER) in the polychaete worm _Capitella teleta_ (Cte), collected using whole-mount in situ hybridization and reverse transcription quantitative polymerase chain reaction (RT-qPCR). The dataset consists of text, CSV, R script, and TIFF image files and provide insights into the spatial and quantitative expression patterns of ER across developmental stages, anatomical regions, and sex-specific life stages. We performed whole-mount in situ hybridization on larval stages 4-8 to localize ER expression with images captured using a SPOT FLEX digital camera. We performed RT-qPCR in C. teleta juveniles (whole bodies) and adult worms (whole body, anterior portions, and gastrointestinal tracts. Juvenile and adult samples were pooled (10 worms per pool for juveniles, 5 worms per pool for adults); anterior portions of worms were also pooled (4 heads per pool). Gastrointestinal tracts were from individuals. For whole body adults, we obtained samples from male, female and hermaphrodites. For anterior portions and gastrointestinal tracts, samples were from male and female only. This data includes cycle threshold (Cq) values for the genes: ER (estrogen receptor), 18s RNA (18S ribosomal RNA), and elongation factor 1 (elf). Sample processing included RNA extraction using TRIzol, cDNA synthesis, and gene expression analysis using the MCMC.qPCR package in R. This resource supports research on endocrine regulation, developmental gene expression, and molecular responses in marine invertebrates. The study was conducted at McMaster University and funded by the Natural Sciences and Engineering Research Council of Canada (NSERC).