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Past Shows
June 25, 2005
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Creating Chimeras
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The Chimera of Ancient Greece - Artist's rendition
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The ancient Greek created the concept of the chimera. In their legends she was a fire breathing animal, with the head of a lion, the body of a goat and the tail of a snake. Today modern medicine creates its own chimeras. But rather than monsters, these animals are helping us to understand some of the mysteries of diseases like cancer.
Dr. John Dick, from the University of Toronto, is learning the secrets of leukemia with his chimeras. He's created mice that have human blood running through their veins. He says one major advantage of working with chimeras is it speeds up the process of therapy development.
Another researcher who's created chimeras is Dr. Evan Balaban, from McGill University. His chimeras are birds; chickens, where part of their brain comes from quails. This change in brain cells has caused the birds behaviour to change, making the chicks act like baby quails.
Today, researchers are turning their attention to studies of the brain. There are some who want to transfer human neurons into mice. And that has ethicists concerned. Dr. Cynthia Cohen, from Georgetown University, says the public doesn't want to see animals that have "human" traits, such as speech or the ability to do math. She thinks we need more public education before we start work with new types of chimeras.
Phillip Karpowicz, a researcher from the University of Toronto, thinks concerns about mice developing human abilities are overblown. While he says it's possible, it's extremely unlikely that mice skulls would be large enough to hold human brains.
For Dr. Francoise Baylis, at Dalhousie University, the big concern is that we're moving too fast to develop this technology. She'd like full public consultation to decide what research is appropriate, and what to do if we create new species that share some characteristics with the human race.
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Redback Spider Sex
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A corpse indicates what awaits a male redback spider entering a female's web - Courtesy, Dr. Andrade and Ken Jones
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Humans have, for the most part, figured out how to change sexual reproduction from something of a biological necessity, to something pleasurable. Not so for the redback spiders. For them sex is deadly serious. Literally. We know that many male spiders get eaten by the female after mating. That’s what scientists call sexual cannibalism. But as Dr. Maydianne Andrade has discovered, the redback spider has added a rather brutal twist to the cannibalistic mating ritual. Like most spiders, the female redback has two separate sperm storage organs. That means the male needs to mate with her twice to maximize his reproductive success. The catch is that the female redback likes to start eating the male while she's mating with him. To get to the second mating, the male redback has developed a trick where he sucks in his belly, as it were, to protect his vital organs from the female's attack. This allows him to survive long enough to mate once, court her again, and mate with her a second and last time before she finally does him in. Dr. Andrade is an assistant professor of zoology at the University of Toronto, Scarborough Campus.
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Low Light Life
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Hydrothermal vent bacteria, GSB1
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Life blooms in the deep-sea oases formed around hydrothermal vents, but it lives in the dark, as these vents occur far deeper than sunlight can penetrate. The energy for the bacteria that form base of the food chain is supplied by the chemical soup that circulates up from the vents, not from the solar energy that fuels most life on our planet. That makes it all the more surprising that Dr. Tom Beatty, a microbiologist from the University of British Columbia, and his team have found a photosynthetic bacterium at one of these vents. This bacterium ekes out a living from the minimal light generated by infra-red energy from the hot environment and stray photons produced by chemical reactions. These light levels are so low that they're undetectable by human eyes. That bacteria can live under such circumstances suggests that this kind of environment might have been the place where photosynthesis first evolved.
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Chickadee Communication
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Black Capped Chickadee |
The chickadee's chirping sounds like pleasant background noise to human ears, but Chris Templeton, a graduate student in the department of biology at the University of Washington in Seattle, has found that for the chickadees it means much more. Despite the apparent simplicity of the call, chickadees can communicate where they've spotted a predator, what kind of action to take (hide or attack) and how dangerous the particular predator is. It's a level of detail in the call that hadn't been suspected before.
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Web Extra: Some Crickets Like it Rough
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Male alpine bush crickets (top) make for rough lovers - Courtesy, Dr. Vahed |
The cricket equivalent of dinner and a movie before moving in for the first kiss is the song males produce by vibrating their wings. Female crickets appreciate this kind of serenading before letting a male mate with her. But according to Dr. Karim Vahed, there’s one species - the alpine bush cricket - where the males are so virile they don’t have time for any gentleman-like behaviour. They simply sneak up on the female, wrestle her to the ground and force their way with her. Or him. The crickets are so keen to spread their sperm they will jump on any cricket that moves: young, old, male or female. And not only that, after a recovery of as little as 18 seconds these males are ready to go again. Other crickets need to rest for several days between mating. Dr. Vahed is a Reader in Behavioural Ecology at the University of Derby and he thinks the rough sex might be advantageous to the female. It appears the stronger the male and the better able he is at holding the female down, the stronger their offspring.
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Question of the Week: Radiation & Cancer
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Philip Winter in Saskatoon writes: If radiation can cause cancer, why is radiation therapy used to treat cancer?
To answer this question, we are joined by Dr. David Skarsgard, a radiation oncologist at the Saskatoon Cancer Centre.
Last week
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