Comments by J. C. Spencer

Trehalose is at the forefront of new discoveries that are emerging in glycomics, genomics, cryogenics, and cryobiology. The little pest called the springtail bug is providing new insights into its own survival by using trehalose as a natural antifreeze to dehydrate and rehydrate. Identifying antifreeze genes may open a whole new world of science.

Today�s story as published by ScienceNews:

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Sleeping ugly

Study reveals genetic details behind springtails� winter survival
By Laura Sanders
Web edition : 9:28 am July 22, 2009

FREEZE DRIED: Arctic springtails (Megaphorura arctica) dry themselves out to survive harsh winters. These scanning electron microscope images show a full-sized springtail (top, about 3 millimeters long) and one that�s ready to hunker down for winter (bottom).Courtesy of K. Robinson and M. R. Worland

Instead of chopping firewood and pulling out the mittens to prepare for chilly winter days, the Arctic springtail hunkers down and dries itself out. A study published online July 21 in BMC Genomics identifies some of the genes that allow for the millimeters-long arthropod�s extreme wintering stunt.

When temperatures drop below freezing, Arctic springtails (Megaphorura arctica) lose a massive amount of water and shrivel into little husks. In this way � a method called cryoprotective dehydration � the critters ride out harsh winter temperatures. When conditions improve, the animals rehydrate, dust themselves off and crawl away.

�This whole question of what happens during dehydration is terribly interesting,� says David Denlinger, an insect physiologist at Ohio State University in Columbus. �Here is an animal that has figured out how to survive � dried out.�

Study leader Melody Clark of the British Antarctic Survey, based in Cambridge, and her colleagues collected springtails from mossy areas beneath cliffs in the Arctic and took them back to the laboratory in England. Once there, the researchers set up an experiment to monitor which of the springtails� genes are active during dehydration and rehydration.

�We�ve tried to emulate what happens in winter,� Clark says. Because room temperature is too balmy for the Arctic animals, she and her colleagues kept the springtails at about 5� Celsius (41� Fahrenheit) and gradually chilled them to -7� C. Between 0 and -2� C, the springtails started to darken and shrivel, eventually entering dormancy. Some of the springtails were allowed to gradually warm back up to 5� C over the course of 18 hours.

Using a hand-built gene chip that catalogues thousands of Arctic springtail genes, the researchers found genes that were active in the shriveled, dry animal and genes that were active after the animal had just rehydrated. Clark says the experiments turned up many of �the likely suspects,� genes whose products help protect cells from damage under extreme conditions.

For instance, the gene for trehalose, a sugar that serves as cellular antifreeze, was more active when the springtails were dehydrated, the researchers found. Genes that encode proteins that continuously help refold damaged proteins were also more active in the dehydrated state. �These genes help keep everything going until conditions return to normal,� Clark says. As the animals rehydrated, genes that encode proteins important for producing energy and remodeling tissues were more active, providing a genetic glimpse into the recovery process.

Not much was known about the genes responsible for such extreme survival, Denlinger says. �This paper provides the best datasets so far, and points to interesting clues about how it [the springtail] survives.�

Understanding animals� strategies for getting through harsh conditions � particularly freezing temperatures � may be relevant for the medical field, including long-term tissue storage, Denlinger says. Of the Arctic springtails� tricks, he says, �It would be a wonderful thing if we could do that to transplant tissues.�

http://www.sciencenews.org/view/generic/id/45792/title/Sleeping_ugly

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Scientists identify 'antifreeze' genes
[Date: 2009-07-22]

EU-funded researchers have identified the genes that allow insects called Arctic springtails to survive temperatures as low as -14�C. The study, published in the journal BMC Genomics, was supported in part by the SLEEPING BEAUTY ('Dormancy of cells and organisms-strategies for survival and preservation') project, which is funded under the 'New and emerging science and technology' (NEST) Activity area of the Sixth Framework Programme (FP6).

'This is the first in-depth molecular study on the underlying cold survival mechanisms in this species,' commented Melody Clark of the British Antarctic Survey, the lead author of the article. 'Such information is not only of interest to ecologists, but also to the medical field of cryobiology.'

Many species of springtail can survive low temperatures; most achieve this by using the 'freeze avoidance' technique, and some use freeze tolerance. However, the Arctic springtail, Megaphorura arctica, uses a third, rarer technique known as cryoprotective dehydration. As temperatures fall, these tiny creatures dehydrate themselves, taking on the appearance of shrivelled husks in the process.

When the weather becomes more clement, the insects rehydrate themselves and resume their normal activities.

In this study, researchers from the British Antarctic Survey and the University of Novi-Sad in Serbia teamed up to identify the genes controlling the processes of dehydration and rehydration.

Their analyses revealed that a wide range of genes become active as temperatures fall, including genes controlling the production of a natural antifreeze called trehalose as well as genes involved in tissue and cell remodelling.

When temperatures rise and the springtail recovers, genes involved in energy production, tissue repair and cell division are activated. The findings could have important implications for those working on techniques for preserving cells and tissues at low temperatures for long periods.

'This is part of a larger European project called SLEEPING BEAUTY, which is looking at how different animals survive desiccation,' said Dr Clark. 'Understanding how animals survive harsh cold environments will hopefully provide novel solutions for medical research and preserving tissues for transplant operations.'

For more information, please visit:

BMC Genomics:
http://www.biomedcentral.com/bmcgenomics/

British Antarctic Survey: http://www.antarctica.ac.uk/

Category: Project results
Data Source Provider: BMC Genomics
Document Reference: Clark, M.S. et al. (2009) Surviving the cold molecular analyses of insect cryoprotective dehydration in the Arctic springtail Megaphorura arctica (Tullberg). BMC Genomics 10:328. DOI:10.1186/1471-2164-10-328.
Subject Index: Coordination, Cooperation; Environmental Protection; Life Sciences; Medicine, Health; Scientific Research

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