Credit: German Orizola
The levels of radiation to which the frogs living in Chernobyl were exposed did not affect their lifespan or their rate of aging. These two characteristics do not actually differ between samples taken in areas with high levels of radiation and those in monitoring areas without radiation. No differences were found in levels of corticosterone, a hormone associated with the stress response, depending on the radiation these amphibians receive.
These are the main results of research conducted by the University of Oviedo and the Doñana Biological Station CSIC – in which international experts collaborated – which analysed, for the first time, the possible long-term effects of radiation on the lifespan and rate of aging of Chernobyl animals.
The work was published in the journal Biology Letters. German Orizola, professor of zoology at the University of Oviedo, highlights that these results indicate that “the levels of radiation to which frogs are currently exposed at Chernobyl will not be sufficient to cause chronic harm to these organisms.”
Developing this type of study that accurately measures radiation exposure and analyzes long-term biological traits, such as age and rate of aging, “is essential to properly assess the current impact of the accident on wildlife.” “This work reinforces the role of the Chernobyl Exclusion Zone as a life refuge,” adds this researcher. Wilderness must be preserved.”
The authors of the paper recall that almost four decades have passed since the accident occurred at Reactor No. 4 at the Chernobyl Nuclear Power Plant (Ukraine). During this time, radiation levels decreased dramatically in the initially affected areas.
It is estimated that less than 10% of the radiation released in the accident remained, and some of the more dangerous isotopes, such as iodine, disappeared within a few months of the accident.
In fact, recent studies show that Chernobyl has become one of the largest nature reserves in Europe. This explains the importance of carefully assessing the extent to which this incident continues to have harmful effects on the environment today.
Work that started in 2016
The team led by German Orizola has been working in Chernobyl since 2016, studying the condition of animals in the area.
Their studies focused on amphibians, specifically the oriental frog (Hyla orientalis). Previous research revealed no effects of current radiation exposure on various physiological and morphological parameters associated with the health status of this species.
In this work, scientists examined the effects of radiation on the lifespan and rate of aging of these amphibians. This is a key aspect of assessing the long-term effects of radiation exposure, because it can reflect the accumulation of damage throughout an animal’s life.
The fieldwork was carried out in collaboration with Pablo Burraco, researcher at the Doñana Biological Station, in three successive campaigns in Ukraine between 2016 and 2018.
In this study, the researchers sampled these amphibians along the entire gradient of radioactive contamination found in the region, including from some of the most contaminated areas on the planet to areas with no radioactive contamination. In total, they captured more than 200 males of the eastern St. Anthony’s frog at 14 different sites, and took them to their field laboratory in Chernobyl (Ukraine).
“In all the frogs, we calculated the level of absorbed radiation based on environmental radiation and the content of cesium in their muscles and strontium in their bones. This was one of the most precise assessments of absorbed radiation ever made on a vertebrate at Chernobyl,” says Pablo Burraco.
The researchers point out that in amphibians, it is possible to calculate the age of an individual by counting the growth lines of their bones that form every year, in the same way that the age of a tree is obtained. This work also examined the rate of aging of these individuals using telomere length as a marker.
Telomeres are DNA sequences found at the end of chromosomes, which protect genetic material and shorten with each cell division. In addition, corticosterone levels were measured in individuals’ blood as a marker associated with stress response.
More information: Pablo Burraco et al., Ionizing radiation has minimal effects on lifespan, telomere length, and corticosterone levels in Chernobyl tree frogs, Biology Letters (2024). doi: 10.1098/rsbl.2024.0287
Provided by the University of Oviedo
Citation: Chernobyl frogs exposed to radiation show no signs of accelerated aging or increased stress hormone levels (2024, November 7) Retrieved November 13, 2024 from https://phys.org/news/2024-11-chernobyl-frogs-expose -aging-stress.html
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