Studies examining the hypothalamic-pituitary-gonad axis (HPG) in Anolis carolinensis provide insight into the regulation of this axis under extremely different reproductive conditions. Molecular studies indicate that kisspeptin proteins, transcribed from kiss1 and kiss2 genes, are produced in the hypothalamus where they bind G protein-coupled receptor 54 (GPR54), activating the HPG axis. Gonadotropin inhibitory hormone (GnIH) and its receptors, G protein-coupled receptor 147 and 74 (GPR147 and GPR74), down regulate HPG axis function. In this experiment we examined HPG axis gene expression in the green anole lizard (Anolis carolinensis), a seasonally breeding species with higher steroid hormone levels in the breeding season than non-breeding season, making it ideal for hormone studies. We measured the gene expression of kiss1, kiss2, and GnIH, as well as GPRs 54, 147 and 74 using reverse transcriptase quantitative polymerase chain reaction (qPCR) analysis. This was done by collecting brain tissue from breeding and non-breeding lizards, extracting RNA and reverse transcribing it to cDNA, developing primers for genes of interest, and measuring mRNA via qPCR analysis. We hypothesized an increase of kiss1, kiss2, and GPR54 mRNAs in the breeding season, and a decrease of GnIH, GPR147, and GPR74 in the breeding season. Our statistics show no significant differences within sex, season, or an interaction. Our results are most likely due to factors such as stress on anoles during transport and whole brain homogenizations. Though we did not find significant differences in our mRNA measures, it is important to note that this is the first isolation of kiss1 in the anole genome which could provide insight for evolutionary studies on the HPG axis.
Date of Degree
Master of Science (MS)
Science, Engineering and Technology
Peters, J. N. (2018). Gene Regulation in the Hypothalamic-Pituitary-Gonadal Axis of the Green Anole Lizard (Anolis carolinensis). [Master’s thesis, Minnesota State University, Mankato]. Cornerstone: A Collection of Scholarly and Creative Works for Minnesota State University, Mankato. https://cornerstone.lib.mnsu.edu/etds/765/
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