Science Friday: DIY Fruit Fireball | All Polar Bears are Irish | Dolphins Healing Powers; Electroreception of one Species

Fruit Fireballs

You may think that oranges seem are a fairly boring sort of fruit. Discover their more exciting side in this simple experiment.
What you need

Orange peel, ideally from a large orange with a thick juicy skin
A candle

What to Do

If you bend a piece of orange peel you often get a spray of orange oily stuff coming out. The idea is to direct this spray upwards into the side of a candle flame.
Be careful, this can be more effective than you expect. Make sure that your hands and anything else easily damaged by flame is below the candle flame!

How it works at the link

http://www.thenakedscientists.com/HTML/content/kitchenscience/exp/fruit-fireballs/

Today's Polar Bears Trace Ancestry To ... Ireland?

Nearly 12 percent of Americans claim some Irish ancestry. Even President Obama has a little Irish in him. But we've got nothing on polar bears.

According to a study in the journal Current Biology, every polar bear alive today can trace its ancestry to one mama bear that lived in Ireland during the last Ice Age. And what's more, she wasn't even a polar bear: She was a brown bear.

Study co-author Beth Shapiro, an associate professor of biology at Penn State University, tells Guy Raz, host of weekends on All Things Considered, that her team studied DNA extracted from ancient bear bones.

"In every cell, there are two different sources of DNA. There's the mitochondrial DNA, which you inherit from your mother," she says, "and there's the nuclear DNA, which is a mix of the DNA that you get from your mother and your father."

When Shapiro looked at the nuclear DNA, she found that brown bears and polar bears began to evolve separately from each other around a million years ago. But the mitochondrial DNA, the kind you inherit from your mother, told a very different story.

"They diverged only about 20- or 30,000 years ago," she says. "And that difference is intriguing, and it means there's something weird going on in the history of polar bears.

[...]

http://www.npr.org/2011/07/23/138640834/todays-polar-bears-trace-ancestry-to-ireland

Dolphins' 'Remarkable' Recovery from Injury Offers Important Insights for Human Healing

ScienceDaily (July 25, 2011) — A Georgetown University Medical Center (GUMC) scientist who has previously discovered antimicrobial compounds in the skin of frogs and in the dogfish shark has now turned his attention to the remarkable wound healing abilities of dolphins.

A dolphin's ability to heal quickly from a shark bite with apparent indifference to pain, resistance to infection, hemorrhage protection, and near-restoration of normal body contour might provide insights for the care of human injuries, says Michael Zasloff, M.D., Ph.D.

For a "Letter" published July 21 in the Journal of Investigative Dermatology, Zasloff, an adjunct professor at GUMC and former Dean of Research, interviewed dolphin handlers and marine biologists from around the world, and reviewed the limited literature available about dolphin healing to offer some new observations about what he calls the "remarkable" and "mysterious" ability of dolphins to heal.

"Much about the dolphin's healing process remains unreported and poorly documented," says Zasloff. "How does the dolphin not bleed to death after a shark bite? How is it that dolphins appear not to suffer significant pain? What prevents infection of a significant injury? And how can a deep, gaping wound heal in such a way that the animal's body contour is restored? Comparable injuries in humans would be fatal. "

Zasloff explains the dolphin healing process by synthesizing scattered reports of known aspects of dolphin biology.

For example, he proposes the same diving mechanism (diving reflex) that diverts blood from the periphery of the body during a dolphin's deep plunge down in water depths also could be triggered after an injury. Less blood at the body's surface means less blood loss.

As for pain, Zasloff's review suggests the dolphin's apparent indifference "clearly represents an adaptation favorable for survival." Still, he says, the neurological and physiological mechanisms engaged to reduce pain remain unknown.

The prevention of infection is perhaps less of a mystery. Despite gaping wounds and deep flesh tears, those who observe dolphins following shark bites have not noted significant rates of infection. Zasloff says it's likely that the animal's blubber holds key answers.

Blubber and its composition have been studied extensively for many years because it accumulates many toxic pollutants of human origin, such as heavy metals from its food sources, which allows scientists to monitor environmental pollution, Zasloff says. It is therefore well documented that blubber also contains natural organohalogens which are known to have antimicrobial properties and antibiotic activity.

"It's most likely that the dolphin stores its own antimicrobial compound and releases it when an injury occurs," Zasloff predicts. "This action could control and prevent microbial infection while at the same time prevent decomposition around the animal's injury."

Finally, Zasloff explores the ability of the dolphin's wound to heal in a way that restores the dolphin's body contour. He says the dolphin's healing ability is less like human healing and more like regeneration.

[...]

http://www.sciencedaily.com/releases/2011/07/110721095834.htm

Dolphin hunts with electric sense

By Richard Black Environment correspondent, BBC News

A South American dolphin is the first "true mammal" to sense prey by their electric fields, scientists suggest.

The researchers first showed that structures on the animal's head were probably sensory organs, then found it could detect electric fields in water.

Electroreception is well known in fish and amphibians, but until now the only mammal example was the platypus.

Writing in the Royal Society's journal Proceedings B, the scientists say other cetaceans may show the same ability.

The Guiana dolphin (Sotalia guianensis) lives around the east coast of South America, and resembles the much more common bottlenose variety.

Like all of the toothed cetaceans, it hunts and locates using sound.

But the researchers have now shown that at close range, it can also sense electrical signals.

They are not as sensitive as sharks and rays, but can detect signals of the same size as those produced in water when fish move their muscles.

"It feeds in the bottom [of the sea] a lot, and it lives in water where there can be a lot of silt and mud suspended," said project leader Wolf Hanke from the University of Rostock, Germany.

"And echolocation doesn't work at very close range, so this is where electrolocation would come in."

[...]

http://www.bbc.co.uk/news/science-environment-14292330