Global and Gene Specific Regulation in Response to Physiological State in Freeze Tolerant Anuran Dryophytes chrysoscelis

Global and Gene Specific Regulation in Response to Physiological State in Freeze Tolerant Anuran Dryophytes chrysoscelis

Presenter(s)

Elizabeth Claire Sinnathamby

Description

Cope’s Gray Treefrog, Dryophytes chrysoscelis, seasonally tolerates freezing. During this process, it is subject to cellular stress from factors such as metabolic starvation, DNA damage, toxin accumulation (from cellular metabolism), and the risk of protein misfolding. Preliminary transcriptome data indicates that many mRNA transcripts vary in relative abundance within hepatocytes of D. chrysoscelis during discrete periods of warm acclimation, cold acclimation, freezing, and thawing . Physiological changes that occur in this frog are likely the result of epigenetic regulation—an alteration in gene expression that does not influence DNA sequence. This modification in gene expression can be observed by the subsequent change in relative abundance of mRNA transcripts. This thesis investigates the relative abundance of several mRNA transcripts for (1) methyltransferase genes that mediate some epigenetic regulation by transferring methyl groups (global regulation) and (2) genes that mediate stress responses contributing to freeze tolerance (local regulation). All of the genes selected are orthologous counterparts to those found in humans. We hypothesize that methyltransferases important to the freezing process will be differentially regulated (either up-regulated or down regulated) compared to the warm condition, whereas stress genes that enhance the survivability of the frogs during freezing will be up-regulated and those that are metabolically costly will be down-regulated. These results demonstrate trends in mRNA expression within four biological groups (warm acclimated, cold acclimated, frozen, and freshly thawed) that may be relevant to the freezing process. mRNA was isolated from livers of frogs within the four biological groups at the time they were sacrificed. cDNA was created and relative abundance was identified using RTqPCR techniques. Results were analyzed using ΔΔCt logarithm to calculate fold change. Deeper understanding of physiological processes that either contribute to or are metabolically costly to freeze tolerance may have future applications in human tissue banking and cryopreservation of organs for transplants.

Publication Date

4-24-2019

Project Designation

Honors Thesis

Primary Advisor

Carissa M. Krane

Primary Advisor's Department

Biology

Keywords

Stander Symposium project

Global and Gene Specific Regulation in Response to Physiological State in Freeze Tolerant Anuran Dryophytes chrysoscelis

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