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IGF-1 Signaling Pathway and the Epigenetic Memory of Thermotolerance in C. Elegans

AJAS · 2019

Emma Tysinger · New Hampshire Science Academy

Overview

The goal of this study was to see if the Insulin/IGF-1 Signaling pathway (IIS pathway) is involved in the epigenetic memory of thermotolerance in Caenorhabditis elegans (C. elegans). The IIS pathway mediates longevity, metabolism and stress-resistance, which includes thermotolerance. This pathway activates a family of small heat shock proteins (such as hsp16) that helps maintain protein homeostasis by preventing other proteins from unfolding during exposure to extreme heat. It has been shown that higher temperatures can induce a heat resistance that can be inherited in C. elegans. The two experiments presented in this report explore the connection between the IIS pathway and this inherited thermotolerance. The first experiment investigated the duration of the inherited thermotolerance by analyzing the death rates of C. elegans at extreme temperatures (37ºC) for progeny of nematodes grown in warmer (25ºC) and optimal (20ºC) temperatures over 5 generations. The control group was the progeny of nematodes grown at 20ºC and the experimental group was the progeny of nematodes grown at 25ºC to induce thermotolerance. Wild type worms and two strains of C. elegans with mutations in the IIS pathway (daf-16 and age-1) were compared to see if the number of generations that inherited thermotolerance in the experimental group would change. The daf-16 was a null mutation (less thermotolerant) and the age-1 was a down-regulated mutation (more thermotolerant). Wild type and daf-16 mutants inherited the thermotolerance for 4 generations whereas age-1 mutants inherited the thermotolerance for 5 generations. An ANOVA test among the three strains for each generation showed that there was no statistical difference in the rate at which the thermotolerance was lost among the three strains (p > 0.05). This suggests that this pathway is not responsible for how long the epigenetic memory of thermotolerance lasts. The second experiment compared the relative expression levels of heat shock protein 16 (hsp-16.1 and hsp-16.2) after heat shock in the progeny of the control (20ºC) and experimental (25ºC) groups using quantitative real-time PCR (RT-PCR). There was no observed trend in reference to the association between heat shock protein and inherited thermotolerance. Although initial results are inconclusive, this experiment established a reliable RNA extraction and RT-PCR protocol for future use in our lab.

Competition history

  • AJAS 2019 Category not listed

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Source: AAAS Annual Meeting (Confex) / American Junior Academy of Science

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