How Do Trees Survive the Long, Dark Winter?

winter trees

Like other living organisms that inhabit cold climates, the main issue a tree must contend with in cold conditions is the prevention ice crystal formation within its cells. (Photo credit: Corbis)

Leafless tree branches set against a snowy backdrop set a rather bleak scene. However, while it may appear lifeless, deciduous trees have several strategies to survive the cold and dark conditions of winter. [Read more…]

Songbird Survival in Winter

cardinal sitting on snow-covered tree branch

Songbirds use a number of techniques to survive during the winter. (Photo credit: Jaki Good Miller/Getty Images)

When it’s extremely cold outside, you might bundle up in multiple layers, put on gloves and a hat, and wrap a scarf around your neck. But what do songbirds do to survive cold winter temperatures?

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Arctic Springtails Dehydrate Selves to Survive Harsh Conditions

The harsh conditions of the tundra are no match for the hardy Arctic springtail. (Photo credit: John Schwieder/Alamy)

The Arctic springtail (Megaphorura arctica), also referred to as a snow flea, is a small, wingless insect that lives in the Arctic tundra. This animal gets its name from its ability to catapult itself using a rigid tail that typically remains folded underneath its body and releases in the face of danger. However, in general, the springtail moves from one place to another by crawling.

The Arctic springtail lives in damp, boggy habitats and feeds on organic waste on the forest floor. One of the more interesting features of the Arctic springtail is its ability to survive the freezing temperatures of an Arctic winter. Before periods of extreme cold set in, the springtail dehydrates itself into a small husk. When warmer temperatures arrive, the springtail rehydrates itself and resumes normal activities. This method of survival is called cryoprotective dehydration. Other animals that use this survival method include an Antarctic nematode, an enchytraied worm, Antarctic midge larvae, and the cocoons of a certain species of earthworm.

During the process of cryoprotective dehydration, water is lost from the springtail’s body across a diffusion gradient between the animals super-cooled body fluids and the ice in its surroundings. At a certain point, the springtail loses enough water from its body that its body cannot freeze and it enters a state of metabolic activity suspension.

Recently, scientists conducted a research study to better understand the genetics behind the process of cryoprotective dehydration in Arctic springtails. The study was led by Melody Clark of the British Antarctic Survey (BAS) and featured contributions by her colleagues at the BAS and faculty members of the University of Novi-Sad in Serbia.

The Arctic springtail looks quite similar to its southern cousin, the Antarctic springtail (Cryptopygus antarcticus), pictured here. Magnification unknown. (Photo credit:British Antarctic Survey / Photo Researchers, Inc.)

For their study, the scientists created 6,912 Arctic springtail clones in order to examine the processes and genes involved in this survival method. The researchers studied the springtail’s response to cold- and salt-induced dehydration. They found that cold-induced dehydration was connected with the movement of trehalose, a natural antifreeze contained in the springtail’s body. Trehalose protects cellular systems and tissues from freezing. When conditions were returned to normal, the springtail’s recovery process was marked by the activation of genes involved in energy production, leading to protein production and cell division.

This research is part of a larger project focusing on determining how different species of animals survive desiccation. Scientists are interested in studying this phenomenon as understanding how it works may prove useful in the development of processes and technology related to human medicine such as preserving tissues for transplants.

The results of the scientists study were published online in the July 21, 2009 edition of the open-access journal BMC Genomics. In addition to study author Melody Clark, other researchers who contributed to the report included Michael A. S. Thorne, Jelena Purac, Gavin Burns, Guy Hilyard, Gordana Grubor-Lajsic, and M. Roger Worland.

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