Periodic Reporting for period 1 - UnravelOxStress (Oxygen, telomeres and sex: experimental elucidation of oxidative stress effects in life history evolution)
Reporting period: 2020-03-02 to 2022-03-01
Oxidative stress refers to the imbalance between antioxidants and reactive oxygen species (ROS) generated during aerobic respiration, and it has often been hypothesized to play a central role in disease and life history evolution, including ageing. However, whether oxidative stress modulates patterns of growth, ageing or survival is still an enigma, largely because the high reactivity of ROS makes oxidative stress difficult to measure. This project aimed at resolving the long standing conundrum of the effects of oxidative stress on ageing and key fitness components using a novel non-invasive experimental approach that bypasses the side effects of pharmacological approaches. Captive zebra finches were exposed to hyperoxic air in a specially designed cabinet and this project was able to show that this manipulation increased oxidative stress levels in blood. The same hyperoxic treatment was then applied to nestlings to test how oxidative stress affects cellular ageing (telomere attrition). Telomeres are highly conserved DNA structures at the ends of eukaryotic chromosomes that shorten with cellular division and oxidative stress, thus suggesting a role in the ageing process. This part of the project is currently under analyses but upon publication, it will shed light on the roles of oxidative stress in life history evolution and telomere dynamics, and on whether the effects of oxidative stress on increased telomere shortening seen in vitro are also observed in vivo.
During this project, we were also able to test the effect of other extrinsic stressors on telomere shortening. Parasites are known to increase oxidative stress, and using a wild population of jackdaws this project showed that infection with a blood-sucking parasite during the developmental stage increases telomere shortening.
The results from this Action have significant societal impact. Understanding the underlying mechanisms of ageing in natural and captive model populations aids in the development of human ‘healthy ageing’ policies and conservation policies, for example by improving the management of endangered species that exhibit declining reproduction with age. By producing high impact publications the project will also inform the specialised audience ranging from evolutionary biologists, physiological ecologists or conservationists to immunologists or biomedical researchers.
During this project, we were also able to test the effect of other extrinsic stressors on telomere shortening. Parasites are known to increase oxidative stress, and using a wild population of jackdaws this project showed that infection with a blood-sucking parasite during the developmental stage increases telomere shortening.
The results from this Action have significant societal impact. Understanding the underlying mechanisms of ageing in natural and captive model populations aids in the development of human ‘healthy ageing’ policies and conservation policies, for example by improving the management of endangered species that exhibit declining reproduction with age. By producing high impact publications the project will also inform the specialised audience ranging from evolutionary biologists, physiological ecologists or conservationists to immunologists or biomedical researchers.
This project was significantly impacted by the Covid-19 pandemic and its restrictions. The experiments that were originally planned required an oxygen-pumping machine that was limited to medical use during the Covid-19 outbreak, coinciding with the start of the project. This and other limitations (i.e. postponed animal experimentation courses required to proceed with experiments) incurred in significant delays and adjustments to the objectives had to be made. The work that was conducted during the first year included fieldwork preparations for the study on the wild jackdaw population, fieldwork, animal experimentation and radioactive protection officer course and analyses of results. During the second year of the project, the facilities were arranged for animal housing and a pilot study was conducted leading to approval from the animal welfare committee on the zebra finch experiment. Then the breeding stage commenced and the families were moved to the hyperoxic cabinets for the main experiment on the effects of oxidative stress during development. The researcher received training in the laboratory techniques and the results from this experiment are currently being analysed. The dissemination of results has been limited due to cancellation or postponing of conferences but the researcher is attending the Society for Experimental Biology conference in Montpellier, July 2022, in which the results from this project will be disseminated as an oral contribution. Other means of results dissemination included talk in weekly group meetings and training of early career researchers, Master students and undergraduate students (1 Master student and 3 undergraduate students).
Progress beyond the state of the art include the novel results showing that a blood-sucking parasite affects nestling telomere shortening in a wild bird population, which are currently being written into a scientific paper; and the novel and non-toxic experimental manipulation of the oxygen conditions in the newly designed cabinets, that has resulted in a successful manipulation of the physiological oxidative stress levels in captive bird species. Despite the limitations and delays in the project, this work will result in at least 4 scientific publications: 2 on the effects of parasites on ageing in a wild bird population, and 2 on the relationship between oxidative stress, ageing and life-history decisions in a captive bird population. The longer-term effects of the developmental manipulations on life-history decisions, ageing and survival parameters will continue to be monitored after the end of this project. The results on the relationship between oxidative stress and telomere shortening during development will be presented in international conferences, demonstrating the impact that the research carried out during this project will have in the scientific community. Regarding impact to a wider and more general audience, given the limitations during the pandemic, no courses or workshops could be organised in the proposed institutions throughout Europe, but this are still pending and plans will be made to arrange these and disseminate the above-mentioned results. So far, 4 students have been trained, showing how this project has already generated an impact in early-career researchers that have the potential to be incorporated into the academic workforce.