Relationships between the transcriptome and physiological indicators of reproduction in female rainbow trout over an annual cycle

Abstract

Normal transcriptomic patterns along the brain-pituitary-gonad-liver (BPGL) axis should be better characterized if endocrine-disrupting compound-induced changes in gene expression are to be understood. Female rainbow trout were studied over a complete year-long reproductive cycle. Tissue samples from pituitary, ovary, and liver were collected for microarray analysis using the 16K Genomic Research on Atlantic Salmon Project (GRASP) microarray and for quantitative polymerase chain reaction measures of estrogen receptor (ER) isoform messenger RNA (mRNA) levels. Plasma was collected to determine levels of circulating estradiol-17β (E2), follicle-stimulating hormone (FSH), and luteinizing hormone (LH). As an a priori hypothesis, changes in gene expression were correlated to either circulating levels of E2, FSH, and LH, or ER mRNAs quantified by quantitative polymerase chain reaction. In the liver, most transcriptomic patterns correlated to levels of either E2, LH, or ERs. Fewer ovarian transcripts could be correlated to levels of E2, ERα, or FSH. No significant associations were obvious in the pituitary. As a post hoc hypothesis, changes in transcript abundance were compared with microarray features with known roles in gonadal maturation. Many altered transcripts in the ovary correlated to transcript levels of estradiol 17-beta-dehydrogenase 8 or 17 B HSD12, or to glycoprotein alpha chain 1 or 2. In the pituitary, genes involved with the growth axis (e.g., growth hormone, insulin-related growth factor binding protein) correlated with the most transcripts. These results suggest that transcriptional networks along the BPGL axis may be regulated by factors other than circulating steroid hormones.

Gene Expression Networks Underlying Ovarian Development in Wild Largemouth Bass (Micropterus salmoides)

“…protocadherins, cathepsins, apolipoproteins, immune-related, steroid-related, and ribosomal genes) corroborate other reports in fish; rainbow trout [4], [6], [33], fathead minnow ( Pimephales promelas ) [9], zebrafish ( Danio rerio ) [34], and Senegalese sole [8]. Thus, there are conserved molecular events that correspond to maturation and development of oocytes within the teleostean ovary.…”

Plasma Nesfatin-1 Is Not Affected by Long-Term Food Restriction and Does Not Predict Rematuration among Iteroparous Female Rainbow Trout (Oncorhynchus mykiss)

“…4). In vitro work suggests that FSH is regulated at the level of both transcription and secretion by the interaction of GnRH hierarchical stimulation and E2 feedback [64], and thus, pituitary expression of fsh-β may not be directly correlated with circulating levels of FSH peptide [65]. In addition, our ability to detect treatment differences in pituitary fsh-β mRNA was less than for plasma E2 due to the number of lethal and non-lethal samples at each time point ( e.g.…”

Defining the role of omics in assessing ecosystem health: Perspectives from the Canadian environmental monitoring program

“…To date, omics information is being gathered preferentially in the female [65,66,92,122], although researchers are beginning to examine the omics response of males [123].…”

“…Seasonal variability influences the transcriptome, proteome, and metabolome, yet there are no common sampling periods suggested or followed in the literature for molecular endpoints (Table ). The variability in the transcriptome in relation to season has been studied in rainbow trout , striped bass ( Morone saxatilis ) , and others. To explore this further, we analyzed microarray data (gene expression omnibus accessions GPL18037, GSE57394 and GPL18038, GSE57865) for rainbow darter over the annual reproductive cycle, and discovered that in this case, global gene expression and quantitative polymerase chain reaction data were most variable during the postspawning season; thus the time of year that encompasses this reproductive stage may be an unfavorable sampling period for assessing critical effects in the field .…”