The effects of circadian rhythm disruptions on monarch butterflies Restricted; Files Only

Aljohani, Ahmed (Spring 2022)

Permanent URL: https://etd.library.emory.edu/concern/etds/j098zc362?locale=en
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Abstract

Organisms have evolved internal biological clocks, known as circadian rhythms, to regulate their physiological functions. Disruptions of circadian rhythms have been associated with the rise of different health complications in multiple vertebrates and mammals, including humans, known as “shift work diseases“.Little is known regarding the developments of such diseases, but one explanation is that the misalignment of circadian clocks directly impacts immune function. Multiple studies have implemented animal models to study this phenomenon in animals. However, most models are heavily focused on a small number of nocturnal species, which may be poor reflections of diurnal situations, thereby highlighting the need for more circadian studies to include diurnal animals. Here we use the diurnal monarch butterflies (Danaus plexippus), one of the most acquainted migratory animals, to investigate the possibility of using them as a diurnal animal model for circadian disruptions and immune studies. Monarchs fight off infections from a naturally occurring virulent parasite; however, little is known about the relationship between their circadian rhythm and immunity. We exposed monarchs to multiple circadian disruptions to investigate their immune rhythmicity. Additionally, we observed monarchs’ behavior to determine if monarchs retrain their circadian rhythms after being disrupted. Our results showed a negative effect on the immune response when monarchs larvae were reared in constant darkness; however, we did not observe immune response rhythmicity in monarchs. Behavioral assays showed that monarchs have sleep rebound behavior to retrain their biological clock after a disruption period characterized by constant exposure to light.  Further investigations into immune mechanisms using other immune measures such as cell lines or using infected monarch butterflies could clarify how circadian rhythms regulate monarchs’ immune response against parasite infection.

Table of Contents

Introduction .....................................................................................................................................1

Method ............................................................................................................................................4

Animal Husbandry  ..........................................................................................................4

Immune stimulation and humoral zone of inhibition........................................................7

Statistics…………................................................................................................................ 7

Results ............................................................................................................................................. 7

Circadian disruptions effect on monarchs’ behavior……………......................................... 7

Circadian disruptions effect on monarchs’ immune response......................................... 11

Discussion........................................................................................................................................ 13

References ...................................................................................................................................... 17

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