Alba, the glowing rabbit that made headlines two years ago for being, well, a glowing rabbit, has met an untimely death, according to the French researcher who genetically engineered her.

Alba the glowing rabbit was 4 years old. Or 2-1/2, depending on who's talking.

The bunny died about a month ago for reasons that are not clear, said Louis-Marie Houdebine, a genetic researcher at France's National Institute of Agronomic Research.

"I was informed one day that bunny was dead without any reason," Houdebine said. "So, rabbits die often. It was about 4 years old, which is a normal lifespan in our facilities."

Alba was an albino rabbit engineered by splicing the green fluorescent protein (GFP) of a jellyfish into her genome. Houdebine said he did not believe the GFP gene played a role in the animal's demise.

Eduardo Kac, the artist who created a flurry by making her a work of art, doesn't buy it, however.

First, Alba's not 4, she's 2-1/2, Kac says (a rabbit's lifespan is up to 12 years), because she was bred by Houdebine specifically for him in January 2000.

Houdebine says he simply picked a rabbit with a gentle disposition that was already in his lab.

Second, he believes Houdebine might be declaring the bunny gone in order to put an end to a two-year, unwelcome barrage of media attention.

If she really is dead, Kac will never realize the final phase of his project, which was to take Alba home and keep her as a pet.

Kac says he and Houdebine originally collaborated on the GFP bunny project, until Houdebine's director put the kibosh on it.

"My director did not understand," Houdebine said. "He said I should not give the rabbit (to someone) outside the lab."

Houdebine said that yes, they spoke about preliminary plans for Kac to use the bunny for his project and take it to an art show in Avignon. But he denies he bred an animal specifically for Kac.

He said it's one of many GFP rabbits generated almost five years ago to be used as a model to follow the fate of embryonic cells in developing embryos.

"When E. Kac visited us, we examined three or four GFP rabbits," Houdebine said. "He decided that one of them was his bunny, because it seemed a peaceful animal."

Houdebine says he would not have agreed to engineer one animal specifically for any artist.

This disputed point has led fellow artists and critics to question whether Kac can rightly take credit for the Alba project.

But Kac insists that Houdebine did, in fact, agree to make the bunny specifically for him.

Kac found out sometime in mid-2000 that Houdebine's director had a problem with the project and would not allow the rabbit to be taken from the lab.

Houdebine was initially apologetic, Kac said. But after an article ran on the front page of the Boston Globe on Sept. 17, 2000, their relationship cooled.

"It was in the Sunday edition right underneath the U.S. gold medal in the Olympics," Kac said. "It was the opposite of what they wanted to see. They wanted to silence the project."

Houdebine and his director were opposed to the now-famous, brilliantly glowing photograph of Alba. They and other researchers say the rabbit doesn't actually glow so brightly and uniformly.

"Kac fabricated data for his personal use," Houdebine said. "This is why we totally stopped any contact with him."

"The scientific fact is that the rabbit is not green," he said. "He should have never published that. This was very disagreeable for me."

Kac believes the scientists were simply afraid of public criticism. Meanwhile, he wanted to do the opposite – to encourage discourse on the transgenic rabbit.

"This director refuses to participate openly in a debate about what is done with public money," he said. "It's very easy to fear and reject what you don't know. As long as they continue to isolate themselves, this mistrust will continue."

The eyes and ears of the rabbit are green under ultraviolet light, Houdebine said, but the fur does not glow, because it's dead tissue that doesn't express the gene. Only if the rabbit were shaved would the body glow, he said.

Other researcher/artists who have done projects similar to Kac's have doubted the photograph's authenticity.

"The picture itself is a construction," said Reinhard Nestelbacher, a molecular biologist at the University of Salzburg, who created a similar art project called Green using mice that carried the GFP gene.

"The rabbit could never look like that," he said. "The main reason is that the GFP gene is expressed, for example, in the skin and cannot be expressed in the hair."

Kac said the photo was not altered. It was taken with an ultraviolet light and a yellow filter, which removes the blue light and reveals the fluorescence – the same way some GFP mice were filmed by a TV crew for his The Eighth Day project, and also the way Nestelbacher photographed his mice.

But a photograph of Nestelbacher's GFP mice with fur shows only a tiny hint of green inside the ear.

Some have suggested that a "control" rabbit should be photographed.

"I wonder if an albino rabbit without the GFP gene would glow green under those conditions," said Hunter O'Reilly, an artist, geneticist and lecturer at the University of Wisconsin at Parkside.

Peter Barna is a color and lighting expert in Brooklyn, and teaches color theory in the graduate school of industrial design at the Pratt Institute. He has done lighting for the Guggenheim Museum in New York as well as NBC.

"There are lots of ways of doing what's been done, but I would not discount the fact that it could be done genetically," Barna said.

Barna said he didn't have enough information to know exactly how the image was created, but there are dozens of possibilities.

A white shirt lit with an ultraviolet light appears to glow, as anyone who's been to a dance club knows.

"Most of it comes from the detergents you use, because they contain phosphorous that makes it look whiter than white," Barna said. "So, who knows, you could bathe a rabbit in it. That's aside from just painting or dying it."

In any case, Barna said it's always tricky to replicate light seen by the human eye in a photograph.

"It's almost impossible to duplicate," he said. "Photographs always do lie in some way or another whether you intend to or not."

Others figured Kac didn't intend for people to think the photo realistic.

"Art misrepresents reality all the time – and he's an artist, not a scientist," said Stuart Newman, a member of the Council for Responsible Genetics and a cell biologist at New York Medical College, "but I think people are beholden to tell the truth."