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Two discoveries win 2019 Nobel Prizes

By Chukwuma Muanya
10 October 2019   |   1:54 am
The discoveries of first extrasolar planet orbiting a Sun-like star and how cells sense oxygen have won the 2019 Nobel Prizes in Physics and Medicine.

First extrasolar planet orbiting a Sun-like star CREDIT: NASA

*First extrasolar planet orbiting star, how cells sense oxygen clinch awards
*Scientists identify new world with water, temperature that could support life

The discoveries of first extrasolar planet orbiting a Sun-like star and how cells sense oxygen have won the 2019 Nobel Prizes in Physics and Medicine.According to the reports published by journal Nature, Michel Mayor and Didier Queloz, who discovered the first extrasolar planet orbiting a Sun-like star, share award with theoretical cosmologist James Peebles; and William Kaelin, Peter Ratcliffe and Gregg Semenza share the award for discoveries that are crucial for understanding diseases such as cancer.

Also, a group of researchers have provided data from the Hubble Space Telescope which reveals there is water vapour in the atmosphere of an Earth-size planet outside the solar system.The findings of the scientists were published in preprint journal on, making the planet a plausible candidate in the search for alien life.

The exoplanet called K2-18b orbits a star smaller than the sun, but it is in the so-called “habitable zone” where it is warm enough for liquid water to exist on the planet’s surface.Meanwhile, cosmologist James Peebles and astronomers Michel Mayor and Didier Queloz have won the 2019 Nobel Prize in Physics for discoveries about the evolution of the Universe and Earth’s place in it.

In 1995, Mayor, at the University of Geneva, and his then-student Queloz announced the first discovery of an exoplanet orbiting a Sun-like star — launching a field that has become one of astronomy’s hottest. They detected the planet through its tiny gravitational pull on the star 51 Pegasi, a technique that is now used to study some of the more than 4,000 exoplanets known to exist.

James Peebles, who is at Princeton University in New Jersey, developed a theoretical framework that the Nobel Committee said forms “the foundation of our modern understanding of the Universe’s history, from the Big Bang to the present day”.

Peebles helped to lay the theoretical foundations for the cosmic microwave background (CMB), the ‘afterglow’ of the Big Bang, and to establish the current ‘standard model’ of the evolution of the Universe. In this model, the mysterious substance known as dark matter plays a central part in assembling large-scale structures of the cosmos, such as galaxies and clusters of galaxies.

Also, a trio of researchers has won the 2019 Nobel Prize in Physiology or Medicine for describing how cells sense and respond to changing oxygen levels by switching genes on and off — a discovery that has been key in understanding human diseases such as cancer and anaemia.

The three scientists are cancer researcher William Kaelin at the Dana-Farber Cancer Institute in Boston, Massachusetts; physician-scientist Peter Ratcliffe at the University of Oxford, United Kingdom (UK), and the Francis Crick Institute in London; and geneticist Gregg Semenza at Johns Hopkins University in Baltimore, Maryland. The team also won the Albert Lasker Basic Medical Research Award in 2016.

Their work has helped researchers to understand how the body adapts to low oxygen levels by, for example, cranking out red blood cells and growing new blood vessels.

Meanwhile, Mayor and Queloz, who are both Swiss and were born in 1942 and 1966, respectively, share one half of the prize, worth nine million Swedish kronor (US$910,000). Peebles, who was born in Winnipeg, Canada, in 1935, will receive the other half.Mayor and Queloz’s discovery “started modern exoplanet science”, says Guillem Anglada-Escudé, an astronomer at the Institute for Space Sciences-CSIC in Barcelona, Spain.

Researchers had previously discovered exoplanets around spinning cores of dead stars known as pulsars, but not around stars similar to our own — which astronomers hope may host habitable planets. The pair’s discovery came as a surprise to the astronomy community. The planet they detected, called 51 Pegasi b, is a gas giant, a type that astronomers had expected would orbit a solar system’s outer reaches.

But the pair found it orbiting around 10 times closer to its star than Mercury is to the Sun. The discovery was an early sign that other planetary systems might not follow the template of our own Solar System.

Meanwhile, a cancer biologist at the University of Pennsylvania in Philadelphia, Celeste Simon, said: “This is a fundamental discovery that they’ve contributed to. All organisms need oxygen, so it’s really important.”A physiologist at the University of Cambridge, UK, and the Karolinska Institute in Stockholm, and a member of the Nobel Assembly, Randall Johnson, said: “The field really coalesced around this discovery, which was dependent on each one of their findings. This really was a three-legged stool.”

The body’s tissues can be deprived of oxygen during exercise or when blood flow is interrupted, such as during a stroke. Cells’ ability to sense oxygen is also crucial for the proper growth of a developing fetus and placenta, and it’s also important for tumour growth, because the mass of rapidly growing cells can deplete oxygen in the interior of a tumour.

In work conducted in the 1990s, the scientists discovered the molecular processes that cells go through to respond to oxygen levels in the body. They found that central to this is a mechanism involving proteins called hypoxia-inducible factor (HIF) and VHL.

Semenza and Ratcliffe studied the regulation of a hormone called erythropoietin (EPO), which is crucial for stimulating the production of red blood cells in response to low levels of oxygen. Semenza and his team identified a pair of genes that encode the two proteins that form the protein complex HIF, which turns on certain genes and boosts EPO production when oxygen is low.

Meanwhile, Kaelin showed that a gene called VHL also seemed to be involved in how cells respond to oxygen. Kaelin was studying a genetic syndrome called von Hippel-Lindau’s disease; families with the disease carry mutations in VHL, and the condition raises the risk of certain cancers.Ratcliffe and his team later found that the protein expressed by the VHL gene interacts with one of the components of HIF, turning off responses to low-oxygen conditions by marking the HIF component for destruction once oxygen levels rise.

And in 2001, teams led by Kaelin and Ratcliffe both elucidated more details about this process. They discovered that, when oxygen is present, a chemical modification to the VHL protein, called prolyl hydroxylation, allows VHL to bind to HIF, which leads to its breakdown. But this modification is blocked when cells are oxygen-starved, kick-starting the activity of HIF.

As a result, cells can react to low oxygen levels by simply blocking the breakdown of HIF, notes Mark Dewhirst, a cancer biologist at Duke University in Durham, North Carolina. “The cell can respond in minutes.”

The work has led researchers to develop drugs that target oxygen-sensing processes, including those in cancer. Drugs, called prolyl hydroxylase inhibitors, that prevent VHL from binding to HIF and causing its degradation are also being investigated as treatments for anaemia and renal failure. Chinese regulators approved the first of these drugs in 2018.

“You could argue that some aspect of this is going to be germane to all diseases you can think of,” says Simon.Colleagues hailed the trio as role models for other scientists. “They are extremely humble people,” says Dewhirst. “All three of them hold scientific rigour and reproducibility to the absolute highest standard,” adds Simon.

Kaelin, in particular, has taken his field to task for pursuing possible cancer treatments that aren’t backed up by strong evidence. “The most dangerous result in science is the one you were hoping for, because you declare victory and get lazy,” he told scientists at a 2018 talk at the US National Institutes of Health in Bethesda, Maryland.In a 2017 essay in Nature, he offered some advice for peer reviewers: “The main question when reviewing a paper should be whether its conclusions are likely to be correct, not whether it would be important if it were true. Real advances are built with bricks, not straw.”

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