Saturday, 1 June 2013

400-year-old frozen moss brought back to life in scientist’s lab

EDMONTON - In Arctic summers, Catherine La Farge camps out at the toe of the Teardrop glacier on Ellesmere Island in Canada’s North.

The University of Alberta biologist has watched the ice retreat, up to four metres a year now, giving her an unprecedented view of what was entombed under the ice for 400 years — old rocks, mud, and her specialty, ancient moss.

One day, walking along the edge of the ice, La Farge noticed some of the moss had a greenish tinge. That gave her a hunch — could there be life in that old moss after all?

In an amazing experiment, La Farge found the frozen moss was able to revive itself though it had been buried since the Little Ice Age (1550-1850). Her study, published this week in the Proceedings of the National Academy of Science, is shaking up some basic assumptions about land plants.

In the past, when scientists occasionally came across plant material previously frozen under an Arctic glacier, they assumed the plant material was dead. Discoloured and lifeless, it certainly looked like it was.

In 2009, La Farge brought samples back to the lab. On closer examination, she noticed a tiny green stem. There were two possible explanations.

“Either it kept its colour under the glacier or it grew after the moss emerged 400 years later.”

There was only one way to find out.

La Farge ground up the old plant material, put it in petri dishes full of potting soil and set it in the grow chamber next to her office. Then she and graduate student Krista Williams and master’s student David Wilkie watched for signs of life.

It didn’t take long. In about four to six weeks, tiny green filaments or strands called protonema began to grow.

Months later, a dish was almost full of green moss from cells frozen for 400 years. Of 24 samples potted, seven produced new growth.

“It was just incredible,” said La Farge, whose work has given scientists another window into the basic life systems of plants.

“Now we have Little Ice Age moss material that produced juvenile plants.”

In glaciers, there are all kinds of fungi and bacteria, but no one has ever considered that land plants could survive being entombed underneath, she said.

“Now we have to think there may be populations of land plants that survived that freezing. It makes you wonder what’s under the big ice caps in the Arctic and Antarctic and alpine glaciers.

“And we have a 400-year-old lineage of genetic material,” she added.

Mosses are especially hardy and ancient — 400 million years old, she said. Mosses played a key role in moving life from water to land in evolution. They evolved from green algae and paved the way for other land plants.

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