"
1986, ano que o terrível
desastre nuclear de Chernobyl (Ucrânia) aconteceu.
Com o ocorrido, a usina de Chernobyl liberou uma
quantidade letal de
material radioativo que contaminou uma quilométrica região atmosférica.
Em termos comparativos, o material radioativo disseminado naquela
ocasião era assustadoramente quatrocentas vezes maior que o das bombas
utilizadas no bombardeio às cidades de Hiroshima e Nagasaki, no fim da
Segunda Guerra Mundial.
Estudos científicos revelam que a
população atingida pelos altos níveis de radiação sofre uma série de
enfermidades. Além disso, os descendentes dos atingidos apresentam uma
grande incidência de problemas congênitos e anomalias genéticas".
Desde que a cidade foi evacuada, se tornou uma cidade fantasma.....
.....a não ser pela fauna silvestre.
Li um trabalho muito interessante que mostra os
efeitos da radiação nas aves que vivem na região isolada.
A exposição a radiação ionizante causa danos às células e produz compostos chamados de
radicais livres. O corpo se protege contra estes compostos usando
antioxidantes, mas quando a taxa de radicais livres é muito alta, os antioxidantes não dão conta, causando
envelhecimento acelerado, câncer e morte.
Foram capturadas 152 aves de 16 espécies diferentes em regiões diversas dentro do perímetro de isolamento (
algumas mais e outras menos afetadas pela radiação).
Eles coletaram
sangue (
para medir níveis de antioxidantes, danos no DNA e stress oxidativo) e
penas (
para medir os níveis de dois tipos de melanina - a eumelanina e a feomelanina) de cada ave .
A maior parte dos resultados foram surpreendentes: os
níveis de antioxidantes estavam aumentados e o estado geral das aves era ótimo, já o nível de stress oxidativo e os danos no DNA estavam baixos.
No entanto,
as aves que produzem mais feomelanina (
coloração avermelhada e rosada) obtiveram resultados negativos: os níveis de antioxidantes estavam diminuidos e o estado geral das aves era ruim, já
o nível de stress oxidativo e os danos no DNA estavam aumentados.
O motivo disso? A feomelanina utiliza uma grande quantidade de antioxidantes para a sua produção.
Este é o primeiro estudo que mostra que animais conseguem se adaptar a exposição a radiação ionizante.
Desculpa o post longo, mas era um tema meio complexo :)
Boa semana!
Verônica Pardini, DVM
Nearly three decades
since the disaster and
it seems the birds living in the exclusion zone around Chernobyl are
adapting to long-term radiation exposure. And some of them aren’t even
just coping, they appear to be benefiting.
Ionizing radiation damages cells by producing reactive compounds called
free radicals. The body protects itself using antioxidants, but if
their levels are too low, then the radiation produces genetic damage and
oxidative stress (when free radicals overwhelm the bodies defenses), leading to aging and death.
Previous studies of wildlife at Chernobyl showed that chronic radiation
exposure depleted antioxidants and increased oxidative damage. “We
found the opposite,” Ismael Galván of the
Spanish National Research Council says in a
news release.
Using mist nets, Galván and colleagues captured 152 birds from 16
different species at eight different sites inside or near the exclusion
zone, an area that spans 30 kilometers in radius. Humans can’t live
here, although the area has become somewhat of an accidental ecological
experiment. (Pictured, mist nets strung along a pasture near the power
plant.) The team measured the background radiation levels of each site
-- these ranged from 0.02 to 92.90 micro Sieverts per hour.
They took feather and blood samples from each bird before releasing them. In the blood samples, they measured levels of the
antioxidant glutathione, oxidative stress, and DNA damage. With the feathers, they measured levels of
melanin pigments. Eumelanin (black
and brown) and pheomelanin (red and pink) are types of melanin. Because
the production of the latter uses up antioxidants, animals who produce
the most pheomelanins are likely to be more susceptible to the effects
of ionizing radiation. They just don’t have enough antioxidants left
over to fend off the free radicals.
However, birds who produce larger amounts of pheomelanin and lower
amounts of eumelanin pay a cost: poorer body condition, decreased
glutathione, and increased oxidative stress and DNA damage. The two
negatively affected birds -- the great tit (Parus major) and the barn swallow (Hirundo rustica) -- both produce large amounts of the pinkish pigment in their feathers.
Previous lab experiments have shown that, with prolonged exposure to
low doses, humans and other animals can adapt to radiation. And that it
increases resistance to larger, subsequent doses. This study shows the
first evidence that animals in the wild can adapt to ionizing
radiation.
Read more at
http://www.iflscience.com/plants-and-animals/birds-adapting-chernobyls-radiation#tRwRJAkzgtMvDU6B.99
Nearly three decades
since the disaster and
it seems the birds living in the exclusion zone around Chernobyl are
adapting to long-term radiation exposure. And some of them aren’t even
just coping, they appear to be benefiting.
Ionizing radiation damages cells by producing reactive compounds called
free radicals. The body protects itself using antioxidants, but if
their levels are too low, then the radiation produces genetic damage and
oxidative stress (when free radicals overwhelm the bodies defenses), leading to aging and death.
Previous studies of wildlife at Chernobyl showed that chronic radiation
exposure depleted antioxidants and increased oxidative damage. “We
found the opposite,” Ismael Galván of the
Spanish National Research Council says in a
news release.
Using mist nets, Galván and colleagues captured 152 birds from 16
different species at eight different sites inside or near the exclusion
zone, an area that spans 30 kilometers in radius. Humans can’t live
here, although the area has become somewhat of an accidental ecological
experiment. (Pictured, mist nets strung along a pasture near the power
plant.) The team measured the background radiation levels of each site
-- these ranged from 0.02 to 92.90 micro Sieverts per hour.
They took feather and blood samples from each bird before releasing them. In the blood samples, they measured levels of the
antioxidant glutathione, oxidative stress, and DNA damage. With the feathers, they measured levels of
melanin pigments. Eumelanin (black
and brown) and pheomelanin (red and pink) are types of melanin. Because
the production of the latter uses up antioxidants, animals who produce
the most pheomelanins are likely to be more susceptible to the effects
of ionizing radiation. They just don’t have enough antioxidants left
over to fend off the free radicals.
However, birds who produce larger amounts of pheomelanin and lower
amounts of eumelanin pay a cost: poorer body condition, decreased
glutathione, and increased oxidative stress and DNA damage. The two
negatively affected birds -- the great tit (Parus major) and the barn swallow (Hirundo rustica) -- both produce large amounts of the pinkish pigment in their feathers.
Previous lab experiments have shown that, with prolonged exposure to
low doses, humans and other animals can adapt to radiation. And that it
increases resistance to larger, subsequent doses. This study shows the
first evidence that animals in the wild can adapt to ionizing
radiation.
Read more at
http://www.iflscience.com/plants-and-animals/birds-adapting-chernobyls-radiation#tRwRJAkzgtMvDU6B.99
