Killer jellyfish

A jellyfish with a deadly sting has been bred in captivity for the first time by Australian scientists, opening up the possibility of developing an antivenom.

The tiny box jellyfish, with a bell just 12 millimetres long, is responsible for Irukandji syndrome, a potentially fatal condition that attacks the central nervous system.

Researchers Heather Walling and Lisa-ann Gershwin from the CRC Reef Research Centre at James Cook University (JCU) in Townville announced their results this week.

The jellyfish, Carukia barnesi, had gone through a planktonic stage and were now attached to rocks on the floor of an aquarium at the Marine Aquaculture Research Facility Unit at JCU.

Irukandji jellyfish are found around the northern coast of Australia. And the species grown in captivity is one of nine to cause Irukandji syndrome, which killed two tourists in Australia in 2002.

Gershwin said Irunkandji syndrome began with a mild sting, like a mosquito bite. Within an hour, victims experienced severe lower back pain, shooting pains all over the body, cramping, nausea, vomiting, profuse sweating and coughing.

Depending on the species, loss of motor control and paralysis could follow, with some victims eventually dying of brain haemorrhages or heart failure.

Gershwin, who also works at the Australian Institute of Marine Science, said the deadly syndrome could be responsible for many more deaths not diagnosed at first.

"The significance of being able to breed these little guys is huge," said Gershwin.

What do jellyfish eat?

Breeding the jellyfish was the first stage to developing an antivenom, she said, which required between 10,000 and 1,000,000 jellyfish.

She said developing an antivenom would involve extracting the toxin from the stinging cells, chopping the molecule up into "different bits" and testing different concentrations of those bits in animals.

Captive breeding also meant more jellyfish toxins were available for scientists to study potential pharmaceutical benefits, and could also allow for rapid diagnostic techniques for Irukandji stings.

"Because of the incredible potency of the toxins, the likelihood of being able to harvest useful chemicals is very high," said Gershwin.

"Researchers require reliable supplies of the jellyfish, which Mother Nature doesn't always provide. People are poised ready to pounce on the next available specimens."

Gershwin said she wasn't sure what defining factor had allowed them to breed the jellyfish successfully; she said it was "mostly luck". Many researchers had been trying to breed the jellyfish since the 2002 deaths.

Clues to the nervous system

Dr Michael Corkeron from Townsville Hospital, a doctor who is developing a new treatment for the syndrome, said that a better understanding of its physiology would most likely lead to better ways to treat it.

Anything that affected the central nervous system like that might also help researchers understand how the nervous system worked, he said.

And perhaps scientists would find out whether the toxin held clues to mechanisms that could block particular effects on the system, Corkeron told ABC Science Online.

"You have to wonder if something so powerful holds some pharmaceutical benefits," he said. Source