The secret to Antarctic worms’ survival in the most extreme conditions may have implications for future storage of organ transplants, say University of Otago researchers.
With Marsden fund backing, Zoology’s Associate Professor David Wharton, in collaboration with colleagues Dr Craig Marshall (Biochemistry) and postdoctoral researcher Dr Gordon Goodall (also in Zoology/Biochemistry) grew a culture of Antarctic worms or “nematodes” in the laboratory to find out exactly how they cope.
“ This froth of Antarctic worms is the only culture in the world we know of”, Wharton says. “Depending on how quickly freezing occurs, the nematode copes in one of two ways. If there is a rapid freezing, the ice seeds into their bodies making the cells themselves freeze. And if ice forms slowly, they dehydrate rather than freeze as they lose water to the surrounding ice.”
The project culminated in the complete gene sequencing of the ice-active protein in this tiny one millimetre long nematode, a protein that makes the worm capable of enduring both dehydration and freezing - the latter for at least nine months.
There are other cold-tolerant organisms - some plants, insects, fish and bacteria – which produce ice-active proteins, but none quite like this one. “It’s not like the “anti-freeze” in fish – the ice still forms in the body of the nematode, but this particular protein stabilises the ice – it actually stops the crystals growing, which is crucial to its survival,” says Wharton.
A search of gene sequence data-bases turned up nematodes with similar proteins which suggests the Antarctic variety has “adapted this protein to suit its particularly severe conditions.”
While the prime motivation for this work is to fully understand the nature of this protein, “it’s always important to keep an eye open for practical uses,” says Wharton. Experiments with the Food Science Department , looking at how ice-active proteins might be used to help store ice cream for longer without it recrystallising, are already underway.
And while Wharton’s team won’t be pursuing these particular applications themselves, there are other exciting possibilities using ice-active proteins to control the formation and stability of ice – to improve current preserving techniques for transplant organs or sperm, for instance, or to provide frost protection to plants.