* Mars Provokes Curiosity * Plotting Plant Pathogens * Pinning Down the Permian Extinction * Downs: The History of a Disability * Science Fact or Science Fiction - Radiation *



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Mars Provokes Curiosity

Next Friday, November 25, the Mars Science Laboratory Mission will depart on an eight-month journey to deliver the Curiosity rover to the Red Planet.  Curiosity will follow in the footsteps of the immensely successful Spirit and Opportunity rover missions, but should exceed them in nearly every way.  According to the Project Scientist for the mission, Dr. John Grotzinger of the Geology Department at the California Institute of Technology, Curiosity is a bigger, more powerful and more capable machine.  Curiosity will literally climb mountains to look at Martian geology, and unveil more about the history of Mars, when the planet was thought to be warmer, wetter and potentially more hospitable to life.
     

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Plotting Plant Pathogens

leafhopper.jpg This species of Leafhopper is found in both Canada and the US, courtesy John Innes Centre
Phytoplasmas are pathogenic bacteria that infect plants and manipulate them by impairing their defenses against insects, such as sap-sucking leafhoppers.  As a result, the leafhoppers thrive on the infected plants.  In fact, new research by Dr Allyson MacLean - a Canadian scientist - and colleagues at the John Innes Centre in Norwich, England - found that the female leafhopper lays 60 percent more eggs on plants infected by the phytoplasma, known as Aster Yellows Witches Broom.  The phytoplasma bacteria benefit as the newly hatched leafhopper nymphs immediately feed on the infected plant.   As the nymphs mature and migrate, they carry the parasitic bacteria to healthy plants, guaranteeing a life-long relationship.
     

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Pinning Down the Permian Extinction

henderson-ucalgary.jpgCharles Henderson (middle) of the University of Calgary collects material from a sedimentary layer in Shangsi, Sichuan Province, China. Courtesy of Charles Henderson/University of Calgary
The Permian Extinction is thought to be the most devastating of the five major extinctions in the history of the Earth.  Possibly as many as 95% of the marine species, and 70% of terrestrial life on Earth was wiped out.  It may well have been as close as complex life on Earth has ever come to being extinguished.  For all that, however, the date and ultimate cause of the extinction have been uncertain.  Dr. Charles Henderson of the Department of Geoscience at the University of Calgary, and his colleagues, have pinned down the date of the extinction to precisely 252.28 million years ago, and found other evidence that suggests the cause of the event was massive lava flows from a super-volcano in what is now Siberia, which triggered 200,000 years of intense global warming.
      

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Downs: The History of a Disability

downs.jpg
There was a time, not so very long ago, when doctors used to refer to people, whom we now call mentally challenged, as imbeciles, cretins or morons. And we hid them away in places like The Institution for Feeble Minded Children, or the National Asylum for Idiots. The most common reason that thousands of children were locked away in those asylums and institutions, was that they had what we now call Downs, or Down Syndrome - a condition that results from having an extra copy of chromosome 21.  But before the world learned of the genetic causes of Downs, just over 50 years ago, it was universally known as Mongolism, and the people with the condition, Mongoloids. They were shunned, ridiculed, locked up, and often sterilized. 

Much has changed in the past 5 decades, both in terms of our understanding of the genetics of Downs, and our attitudes toward people with Downs. But according to Dr. David Wright, Professor of the History of Medicine at McGill University, our attitudes may not have changed as much as we think.  Dr. Wright has just written the first history of the syndrome, called Downs: The History of a Disability.

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Science Fact or Science Fiction - Radiation

This is another episode of our occasional feature, Science Fact or Science Fiction. From time to time, we present a commonly held idea or popular saying - and ask a Canadian scientist to set us straight on whether we should believe it or not. And today's popular belief comes to us from Tony Corsillo in Toronto, who says - "Flying exposes us to higher levels of radiation."

To help us with this question, we contacted Dr. Pamela Tume, a nuclear engineer at Candu Energy, who has studied flying and radiation. She says it is science fact.

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Theme music bed copyright Raphaël Gluckstein, Creative Commons License by-nc-nd-2.0