Posts Tagged ‘Chernobyl’
“In the beginning there is the stem cell; it is the origin of an organism’s life”*…
C.H. Waddington’s powerful image of embryonic stem cells specializing on a rolling landscape has captivated biologists since the 1950s. As Philip Ball reports, experimental data is finally confirming– and complicating– his visionary ideas…
By the middle of the 20th century, it had begun to seem that biology was almost solved. Charles Darwin’s theory of evolution by natural selection explained how organisms change and adapt. The modern science of genetics showed how it works at the molecular scale. Genes governing the traits of organisms get passed down from parent to offspring, and random mutations create the variations from which natural selection picks the “fittest.” Natural selection and genetics fitted together in what the biologist Julian Huxley christened “the modern synthesis” in his 1942 book). Once it was shown in 1953 that the genes are encoded by DNA, the rest of biology looked like little more than piecing together details.
But not everyone was satisfied. The British biologist Conrad Hal Waddington), known to his friends and colleagues as Wad, thought this focus on genes was all very well. But it wasn’t clear to him, or anyone else, exactly how genes shape the forms and features of organisms — how they reliably generate all the different tissues of the body, in all the right places, during embryonic development. Around the same time that Huxley unveiled the modern synthesis, Waddington presented a novel picture of how this might unfold.
He visualized the developmental process as a landscape with hills and valleys that split every so often like those in a river network. At the very top of the highest hill he imagined a ball, which represented a population of cells in their earliest embryonic form — what we now call stem or pluripotent cells, which have the potential to become any cell type. The progression of the cells towards their fates — to become, say, skin cells, muscle cells, or nerve cells — is like the ball rolling downhill through the landscape.
When the ball reaches a branching point (bifurcation), the model’s “gravity” pulls it to one track or the other: In scientific terms, it must differentiate. Through a particular sequence of such branching decisions, Waddington argued, cells specialize into their mature types, or fates, each expressing a particular set of genes. The cells are restricted to a small number of well-defined states because they are “canalized,” in Waddington’s lexicon: trapped and channeled by the sides of the valley. In this way, a limited number of cell types reliably arise from the activity of an army of genes.
Waddington’s landscape has been “remarkably useful as a conceptual scaffold,” said James Briscoe, a developmental biologist at the Francis Crick Institute in London. “The core ideas — that development is progressive, that cell states are distinct, that bifurcations represent [cell] fate decisions, that canalization implies robustness — all survive.”
“There’s so much richness to some of the concepts Waddington was trying to share,” said Susanne Rafelski, a biochemist at the Institute for Stem Cell and Regenerative Medicine in Seattle.
But the concept was more of a visual metaphor than a representation of an actual biological process. Or so it seemed. In the past several years, researchers have mapped out the real topography of cell-state spaces — in effect, Waddington’s landscapes — from experimental data collected from many thousands of cells over the course of embryonic development. Those analyses are revealing that development is not a mere readout of a genetic program, but rather a dynamic process in which communities of cells build themselves, and the very landscape they navigate, by mutual negotiation and interaction, into an organism.
This cartography of development is now helping researchers understand how identical cells in the early embryo develop into the distinct tissues and cell types of a complex organism. This matters enormously for regenerative medicine and stem-cell engineering, Briscoe said: “If you understand the landscape topology and know where the bifurcations lie, you can in principle design methods that steer cell populations to desired states with precision, rather than by trial and error.”
Waddington’s metaphor, then, could be the key to understanding and reshaping possibilities for what cells, tissues, and embryos can be…
Read on: “How Does Life Unfold? A Landscape Metaphor Comes Into Its Own.” from @philipcball.bsky.social in @quantamagazine.org.
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As we appreciate adaptability, we might send healing birthday greetings to Robert Peter Gale; he was born on this date in 1945. A physician and medical researcher, he conducted important research into leukemia and other bone marrow disorders (e.g., aplastic anemia). Gale was a a pioneer in bone marrow transplantation and co-founded the International Bone Marrow Registry. But he is perhaps most widely known for his assistance to foreign governments in treating radiation victims – to the Soviet Union (1986) after the Chernobyl disaster and to Brazil (1987) following an accident in Goiania. As a specialist in bone marrow transplants, he volunteered to treat Chernobyl victims and was invited by Mikhail Gorbachev to travel with a group to Moscow immediately after the April 1986 accident. He performed bone marrow transplants on 13 Chernobyl victims (though many of the highly exposed Chernobyl survivors have since died from latent radiation effects).
“I’m having a magenta day. Not just red, but magenta!”*…
Your correspondent is still on the road; regular service resumes on or around May 6. Meantime, a colorful update…
Forget about red hot. A new color-coded heat warning system relies on magenta to alert Americans to the most dangerous conditions they may see this summer.
The National Weather Service and the Centers for Disease Control and Prevention on Monday — Earth Day — presented a new online heat risk system that combines meteorological and medical risk factors with a seven-day forecast that’s simplified and color-coded for a warming world of worsening heat waves.
“For the first time we’ll be able to know how hot is too hot for health and not just for today but for coming weeks,” Dr. Ari Bernstein, director of the National Center for Environmental Health, said at a joint news conference by government health and weather agencies.
Magenta is the worst and deadliest of five heat threat categories, hitting everybody with what the agencies are calling “rare and/or long-duration extreme heat with little to no overnight relief.” It’s a step higher than red, considered a major risk, which hurts anyone without adequate cooling and hydration and has impacts reverberating through the health care system and some industries. Red is used when a day falls within the top 5% hottest in a particular location for a particular date; when other factors come into play, the alert level may bump even higher to magenta, weather service officials said.
On the other hand, pale green is little to no risk. Yellow is minor risk, mostly to the very young, old, sick and pregnant. Orange is moderate risk, mostly hurting people who are sensitive to heat, especially those without cooling, such as the homeless.
“When red-hot isn’t enough: New government heat risk tool sets magenta as most dangerous level,” from @AP.
* Stephen King, Needful Things
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As we reassess risk, we might recall that it was on this date in 1986 that Russia announced the Chernobyl nuclear disaster, two days after it happened.
“Oh happy people of the future, who have not known these miseries and perchance will class our testimony with the fables”*…
The Plague of Florence as Described by Boccaccio, an etching (ca. early 19th century) by Luigi Sabatelli of a plague-struck Florence in 1348, as described by Petrarch’s friend Giovanni Boccaccio — Source.
The Italian poet and scholar Francesco Petrarch [see almanac entry here] lived through the most deadly pandemic in recorded history, the Black Death of the 14th century, which saw up to 200 million die from plague across Eurasia and North Africa. Through the unique record of letters and other writings Petrarch left us, Paula Findlen explores how he chronicled, commemorated, and mourned his many loved ones who succumbed, and what he might be able to teach us today…
Love, death, and friendship in a time of pandemic: “Petrarch’s Plague.”
* Petrarch, from a 1347 letter to his brother, who lived in a monastery in Montrieux
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As we learn from history, we might recall that it was on this date in 1986 that the British government banned the slaughter and movement of lambs in parts of Cumbria, Scotland and Wales; heavy rainfall in those areas had showered fallout from the Cernobyl nuclear disaster onto farms there. (The transfer of radionuclides to sheep and goat products is greater than to cattle.) As the ban lifted, animals’ radiation levels were monitored before they were allowed to be sold at market. The number of failing animals peaked in 1992, but some still recorded higher levels of caesium as recently as 2011.
“One ingredient of many fiascos is that great, massive, heart-wrenching chaos and failure are more likely to occur when great ambitions come into play”*…
There’s a term for when a single hiccup triggers a chain reaction that makes everything go absolutely, altogether, totally, and undeniably wrong, causing a large and intricate system to collapse on itself. On the street you might call it a fiasco—but in more formal parlance it’s called “cascading failure.”
Sound familiar? If you’ve been through an electrical grid outage, there’s a good chance you’ve heard it in that context. It’s not a new phenomenon, but it’s a relatively recent term, and the complexity of modern life has multiplied the real-life scenarios for its use in the fields of technology, biology, and finance. The easiest way to think about cascading failure is as a line of tumbling dominoes—or the plot of Jurassic Park, a blockbuster about how the smallest of errors can lead to total catastrophe…
Epic power blackouts, the “flash crash,” coronavirus response, and so much more: “Cascading Failure.”
* Ira Glass, in his introduction to “Opening Night,” Act One of the This American Life episode “Fiasco“… and the funniest 21 minutes of radio your correspondent has ever heard.
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As we consider causation, we might recall that it was on this date in 1986, at 11:10p, that operators at the the Chernobyl Nuclear Power Plant in the Ukraine received the go-ahead to commence a safety test that was scheduled to coincide with a routine shutdown for maintenance. Just over two hours later, an unexpected power surge triggered what we now know as “The Chernobyl disaster”– considered, even after Fukushima, the worst nuclear catastrophe in history. It killed 31 people directly, including 28 workers and firefighters who died of acute radiation poisoning during the cleanup. Experts believe it likewise caused thousands of premature cancer deaths, though the exact number is disputed. To this day, the area around the plant remains so contaminated that it’s officially closed to human habitation.
A view of the facility three days after the incident
“Better to see something once than to hear about it a thousand times”*…
In recent years, the Zone, a highly restricted area in northern Ukraine that surrounds the site of the 1986 nuclear disaster, has become a tourist hotspot. Each morning, tour buses queue at the entry checkpoint where a souvenir shop plastered with nuclear warning symbols peddles neon keyrings and radiation suits. The guides’ t-shirts read: “Follow me and you will survive”. In fact, the dangers are minimal. Along their tightly demarcated routes, these visitors will be exposed to less radiation than during a routine x-ray.
Existing in the shadows of this highly commodified industry is the secretive subculture of the “stalkers”: mostly young Ukrainian men who sneak into the Zone illegally to explore the vast wilderness on their own terms. The name originates from the 1972 Russian science fiction novel Roadside Picnic. Written by brothers Arkady and Boris Strugatsky, it tells the story of contaminated “zones” created on Earth by aliens, in which rogue stalkers roam, hoping to recover valuable alien technology. The book inspired Andrei Tarkovsky’s 1979 cult-classic film Stalker.
Beyond youthful rebellion, the motivations of the modern stalkers are complex, and speak to the national trauma that resulted from a tragedy whose effects will be felt for generations. And now there is another side to the practice. Enterprising stalkers have started offering their own “illegal tours” to travellers seeking a less restricted (and therefore more dangerous) experience of the Exclusion Zone. I joined one such tour in an effort to discover why visitors might chose a stalker over an official guide. Can a subculture that is so tied to deep wells of personal and national loss really offer something of value to an outsider?…
Accompany Aram Balakjian on a beautifully-photographed expedition through the forbidden area: “Into the Zone: 4 days inside Chernobyl’s secretive ‘stalker’ culture.”
* Uzbek proverb
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As we take the tour, we might recall that it was on this date in 2000, via an announcement by then Secretary of Energy Bill Richardson, and after decades of denial, that a U.S. government study conceded that cancer and premature deaths of workers at 14 nuclear weapons plants since WW II were caused by radiation and chemicals.
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