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Title: Environmental and hormonal regulation of epigenetic enzymes in the hypothalamic-pituitary-gonadal axis of the Siberian hamster (Phodopus sungorus)
Author: Coyle, Christopher Simon
ISNI:       0000 0004 8498 4800
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2019
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Many environmental and internal signals contribute to the successful timing of reproduction. Successful reproduction requires the integration of physical, physiological and social stimuli. In seasonal species it is becoming clear that epigenetic modifications to the genome are a robust mechanism to regulate seasonal changes in physiology This thesis attempts to characterise the expression of the DNA methylating enzymes DNMT1, DNMT3a and DNMT3b throughout the hypothalamic-pituitary-gonadal axis in the seasonally breeding Siberian hamster in response to photoperiod, ovarian hormones, and social condition. Using a combination of immunohistochemistry, in situ hybridization, and quantitative PCR, I illustrate the variation in day lengths can regulate DNMT expression in the hypothalamus and uterus (Chapter 2). Furthermore, artificial and natural variation in ovarian hormones can cause decreases in DNMT expression in both the hypothalamus and uterus of female Siberian hamsters (Chapter 3 and 4). Investigating direct effects of estrogen in a hypothalamic cell line model highlights that estrogen is not sufficient to alter DNMT expression alone (Chapter 5). Finally, I show that both chronic and acute social isolation do not regulate the expression of epigenetic enzymes. Although there is an interesting phenomenon observed in chronically isolated individuals kept in short day reproductively inhibitive photoperiods that do not undergo gonadal involution (Chapter 6). Together, the findings illustrate that the expression of epigenetic enzymes can be regulated by both external stimuli and endogenous rhythms.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Phodopus sungorus ; Reproduction ; Epigenetics ; Enzymes