Effect of Temperature on the Growth Rate of Caenorhabditis elegans

Abstract

The growth rate of N2, wild-type, strain of Caenorhabditis elegans was studied at three different temperatures to determine if temperature significantly affects their growth rate. The setup consisted of three treatments, with four replicates each, which included incubation temperatures of 25°C (the control), 17°C, and 11°C. Initially 5 adult hermaphrodites were placed on a transfer plate, and then transferred to 60 mm petri dishes containing Escherichia coli for each replicate, totaling 20 worms for each treatment. Incubated over a period of 9 days, the total number of adult C. elegans was estimated by using grids every 24 hours. The 95% confidence intervals of all treatments overlapped up to Day 4, and started to separate/not overlap for all treatments from Day 4 to Day 9. Thus, the total number of adults for each treatment was found to be significantly different. Plotting a linear relationship of the total number of adults versus time resulted in a correlation coefficient, r, of 0.9386, 0.9491, and 0.7572 for 25°C, 17°C, and 11°C, respectively. The slope of these linear plots were found to be 150.87 ± 18.37, 61.05 ± 6.72, and 13.54 ± 3.87 with units of adults per day for temperatures of 25°C, 17°C, and 11°C, respectively, which also do not overlap. Since the results are significantly different, these quantitative descriptions of the slopes from the linear plot are representations of the growth rates for the corresponding growth temperatures. Despite the significance of the results, there were some sources of error, including the overestimation in counting the adults, the damage done to the worms during pickup and transfer, genetic variation, and non-uniform observation period. We concluded that as the growth temperature decreases, the growth rate of C. elegans also decreases.