After completing my bachelor’s degree in biology, I did my master’s degree in biological sciences, specializing in Ecology, where I started working with seabirds (brown boobies) and their telomeres. In previous studies with wild birds, it has been found that telomere length can positively predict the individuals’ lifespan, similarly as with humans, but also their reproductive performance, as individuals with longer telomeres have been related with producing more offspring throughout several years. Thus, in ecological studies, telomeres are more commonly interpreted as a marker of individual quality. During my master’s, I evaluated if the telomere length of adults was related to their breeding patterns and their physiological phenotype. I found that individuals’ telomere length was positively related to their mitochondrial content in blood, and that individuals mate assortatively by their telomere length, meaning that females with long telomeres are paired with males with long telomeres, and vice versa.

After my master’s, I decided to keep working with birds, specifically with brown boobies, as they are a fantastic study species, and of special interest in studies about cellular aging, such as those with telomeres. Brown boobies are a long-lived species, living on average about 12 years, although there is a report of one individual reaching 30 years. Also, they have a long reproductive period, where both male and female partners incubate their eggs for around 42 days, and then take care and feed their offspring for 3-4 months. During the incubation period and the first 30 days of chick rearing, it is very easy to capture and manipulate both adults and offspring, for example to get blood samples and perform different experiments, making it easy also to perform longitudinal studies.

For my PhD, I tried to expand the knowledge on how telomeres may be related with different physiological mechanisms, and also to the individuals’ breeding performance, making special use of longitudinal studies, where we can assess the change in telomere length through time, as a more robust measure of cellular maintenance, in both adults and chicks.

First, we followed adults during the incubation period and estimated their change in telomere length during this period. We found that most of the individuals elongated their telomeres, and that a higher telomere elongation were found in individuals with bigger clutches, higher hatching success and better body condition. Then, during the chick rearing period, we found that females with longer telomeres were related to perform longer foraging trips towards more oceanic zones, compared to females with shorter telomeres that perform shorter foraging trips nearer to the shore. Further, females that performed longer foraging trips had chicks in better condition, estimated by a higher growth rate. Thus, we can say that in adults, telomeres are positively reflecting the individuals’ capacity for breeding investment.

With chicks, we monitored all individuals during the first 30 days of life, estimating their change in telomere length during this period. We will evaluate how the change in telomere length is related to the gut microbiome colonization and to the acute physiological stress, estimated by the levels of the hormone corticosterone. However, at this moment this work is still in progress. 

During my internship at the UCSF AME Center, I wanted to explore deeper in the physiological mechanisms that can lead to differences in telomere shortening between individuals. Additionally, I was very excited to learn how all the mechanisms that I have mostly studied in birds, can be applied to human clinical research. During this time, I have worked on two projects. The first evaluated how chronic psychological stress can lead to telomere shortening, through the impairment of mitochondrial biology and telomerase activity. The second project was aimed to understand how obesity, estimated by the Body Mass Index (BMI), can promote a faster telomere shortening, evaluating three possible mediators of this: inflammation, oxidative stress and insulin resistance.

For the future, I hope to expand my knowledge on the bidirectional relationship between mitochondrial biology and telomere maintenance, and how this may be affected by the individuals’ current condition, for example being under a situation of chronic stress or depression.