Telomeres dynamics across early life of the Cuban Brown Anole (Anolis sagrei)

Abstract

Telomere length is a key biomarker for cellular senescence and organismal survival. However, relatively little research has been conducted on the dynamics of telomeres in early life, particularly in reptiles. Through the research in this thesis, I focus on telomere dynamics in the early life stages of the brown anole lizard (Anolis sagrei). In my first project, I test if telomere length changes in the blood cells during the transition from embryo to 1-week post-hatching, and whether telomeres in males are females differ at this early stage. To do this I optimize and validate a molecular sexing method to identify sex of the brown anoles that yielded. I use qPCR assay to quantify telomere length in blood cells, and I tested whether telomere length changes during the transition from the embryonic stage, within 24-hour of hatching, and to one-week of age. I found that across the three time points observed that there were no significant differences in telomere length between ages. When testing for sex specific differences in telomere lengths across these time points, I also found no sex specific differences. In the second project, I aimed to determine if the addition of insulin-like growth hormone factors (IGFs) and growth rate would impact telomere dynamics in the early life of the brown anole lizard, and if this response differed by sex. To do this, I introduce IGF-I and IGF-II through periodic injections to juvenile brown anoles and quantified their telomere length in the blood cells at 13-weeks of age. I found no significant differences across injection treatments. When I compared 13-week-olds that received IGF injection treatments to the week one, I also found no significant difference for age in telomere lengths. Lastly, I quantified growth for each individual using total snout-vent-length (SVL) change and body mass change between week 1 and week 13 to test for potential relationships between IGF treatment, growth, telomere length, and sex. I found that telomere length change in the interaction between growth and treatment, where telomere lengths decreased in both orange and yellow treatments but increase in the pink treatment. Sex was also significant in each model with males having longer telomeres relative to females. My work described in this thesis helps to move the scientific community forward in various ways. Firstly, through this work I was able to develop a molecular sexing protocol via qPCR using primer and probe set for an autosomal gene and an X-linked gene alongside telomere analysis via qPCR. Secondly, this work provides the knowledge of telomere dynamics during the early life stages of A. sagrei for cross species telomere analysis. I show that telomeres lengths do not vary in male or female A. sagrei in embryonic stage and at one week of life, but males did have longer telomeres at 13 weeks of life. Further research is needed to understand how telomeres change as the animals continue into adulthood. These findings would provide foundational work to expand upon to better understand telomere dynamics in a model reptile species in future studies. During my time at Auburn University, I have had many more contributions to the scientific field outside of my thesis experimental work. A large portion of my efforts have gone toward to collection, processing of 1,600 A. sagrei eggs, and subsequent care of the animals for a NIH-funded project to develop a new reptile model for sex-specific aging. Periodic collection of biometrics for the 1,200 individuals such as SVL, body mass, back pattern photos and bite force. Collection and preservation of fine tissues including liver, heart, brain, skeletal muscle, and blood tissue for several hundred A. sagrei. Various primer and probe set designs and optimization for molecular sexing to be performed on other species such as brown anole lizards, zebra finches and alligator lizards. Additionally, I helped train many undergraduate researchers in both animal care and data collection procedures and molecular laboratory techniques.