GLOWING ANIMALS: Pictures Shining for Science

Crystal Jelly

How does it glow?

Green fluorescent protein, naturally occurring

What can we learn?

In 1961 researcher Osamu Shimomura of the Marine Biological Laboratory in Massachusetts noticed a molecule in this jellyfish that glowed bright green under ultraviolet light (as pictured).

After extracting the molecule from 10,000 specimens, Shimomura found the protein that creates the glow.

At some point, a light bulb went off. Some of Shimomura's colleagues realized that the protein could be attached to other proteins--enabling scientists to mark proteins of their choice with a green glow.

Since then, Shimomura's green fluorescent protein (GFP) has been used to decrypt previously invisible processes, like the spread of cancer or the development of nerve cells--earning Shimomura and colleagues a Nobel Prize in 2008.

Fluorescent proteins have also been used to engineer some truly strange beasts (and the odd plant), such as the glowing puppies, monkeys, mice, fish and other animals .



Rhesus Macaque Monkey

How does it glow?

Green fluorescent protein, introduced into DNA of egg via virus (2008)

What can we learn?

Scientists at the Yerkes National Primate Research Center in Atlanta are using green fluorescent protein to study Huntington's disease, which destroys nervous tissue.

In 2008 the researchers infected unfertilized monkey eggs with an HIV-like virus, which changed the eggs' DNA to include the defect that causes Huntington's.

The virus also introduced a protein that would make rhesus monkeys fluoresce under ultraviolet light (as pictured)--making it easier to study the effects of the disease on the monkeys' brains.



Cat

How does it glow?

Red fluorescent protein, introduced via a virus into cloned DNA, which was implanted in cat eggs, then implanted in mother (2007)

What can we learn?

Scientists at Gyoengsang National University in South Korea both cloned a Turkish Angora house cat and made it fluorescent—as shown in the glowing cat (left) photographed in a dark room under ultraviolet light. (The nonfluorescent cat, at right, appears green in these conditions.)

The scientists weren't the first to clone a cat--they weren't even the first to clone a fluorescent cat. But they were the first to clone a cat that fluoresces red.

It's hoped that the red glow, which appears in every organ of the cats, will improve the study of genetic diseases.


Tobacco

How does it glow?

Firefly luciferase gene, introduced via a virus into tobacco DNA (1986)

What can we learn?

Iowa State University scientists inserted a genetic structure from fireflies into a tobacco plant, causing it to glow.

Unlike the gleam spurred by green fluorescent protein, the firefly-derived glow--caused by the pigment luciferin and the enzyme luciferase--does not require ultraviolet light to fluoresce. The firefly light, though, does require oxygen and, under some conditions, ATP, a molecule involved in energy storage inside cells.



Nematode Worm

How does it glow?

Green fluorescent protein, introduced into its DNA (2005)

What can we learn?

In 2005 University of Utah biologists wanted to study worm rhythm. They isolated a gene they believed to control swallowing, egg laying, and pooping.

To test their hypothesis, the team tagged the gene with green fluorescent protein in a worm. Sure enough, the throat, intestines, and gonads of the animal all glowed green (pictured at right).

To double-check, the team disabled the gene in another worm. That gave them a worm that could not swallow (left), which died at a small size because it could not eat.

The experiment may sound esoteric, but humans have rhythmic activities--swallowing, ovulating, giving birth, defecating--controlled by a similar gene, so the glowing worm could lead to solutions for a variety of ailments.


Zebrafish

How does it glow?

Green, yellow, and red fluorescent protein, introduced into its DNA (2003)

What can we learn?

In 1999 scientists at the National University of Singapore began working with zebra fish and green fluorescent protein, hoping to engineer a fish that would glow in the presence of toxic chemicals.

In the process, the scientists created fish that fluoresce all the time (under ultraviolet light) and in a range of colors.

A few years later, the first fluorescent pet hit the market, after Singapore had become the first country to authorize the sale of the genetically modified fish in 2003. Later that year "GloFish" (pictured) debuted in the United States, where in 2009 they retail for five to ten dollars at some pet stores.

Though fluorescent pet fish have spawned no scientific advances, they inspired the creation and clarification of laws governing genetically modified pets. The United States, for example, was initially forced to classify the genetic modification as a drug.



Dog

How does it glow?

Red fluorescent protein, introduced via a virus into cloned DNA (2009)

What can we learn?

In the same city that gave the world its first cloned, fluorescent-red cat, another group of Seoul scientists--this time at Seoul National University--engineered the world's first cloned, fluorescent red dog on April 26, 2009.

Ruppy the beagle--a combination of "ruby" and "puppy"--is the first successful clone of a genetically modified dog.

Believe it or not, the glow wasn't the point of the experiment--just evidence of the genetically modified nature of the beast.

The ability to clone genetically modified dogs should improve the study of human genetic diseases in dogs, such as Parkinson's, according to the research team.