Browsing by Author "Malik, Hannan Rauf"

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    Investigating the coordination of thermoregulation by thermosensory mechanisms
    (2021-11) Malik, Hannan Rauf; McFarlane, Sarah; Schnetkamp, Paul; Altier, Christophe; Thompson, Roger
    Thermoregulation is a critical homeostatic process through which organisms maintain cellular and physiological integrity. Depending on how thermoregulation occurs, organisms can be categorized as either endothermic, using heat from metabolic processes for thermoregulation, and ectothermic, not relying on metabolic heat for thermoregulation. Ectotherms also link their body temperature to that of the ambient environment. Both endotherms and ectotherms utilize a superfamily of polymodal proteins known as transient receptor potential (TRP) channels to initiate the thermoregulatory response. TRPM8, a member of the TRPM subfamily, has been characterized as a transducer of cold sensor in various vertebrates through functioning as a cutaneous thermoreceptor. There is still a paucity of information on this protein, whether it is expressed in the skin of the ectotherm, Xenopus laevis and its involvement in the afferent thermoregulatory response. This thesis explores the thermoregulatory response of Xenopus laevis to cooling, as well as the expression and putative function of TRPM8. First, I demonstrate that Xenopus laevis embryos exhibit a rapid, systemic melanosome aggregation upon introduction to non-noxious cool temperatures. Second, I examine the expression of the TRPM subfamily via RT-PCR in Xenopus, and then identify the expression of TRPM8 at the protein level in the skin of this ectotherm. Lastly, I demonstrate the role of TRPM8 in the thermoregulatory response, as a TRPM8 agonist phenocopies the melanosome aggregation seen as a response in cool temperatures, while an antagonist diminishes the melanosome aggregation. My work elucidates the thermoregulatory response of Xenopus laevis, as well as the role of TRPM8 in mediating the melanosome aggregation to add to the growing literature of this ion channel in thermoregulation and transducing cold.