Rising from the depths, mosses that have been frozen in suspended animation for hundreds of year grow again! You may recall that zombie mosses were in the news last summer, well they are back. In this study, published last week in Current Biology, mosses were dug up from an island in Antarctica and regenerated new plants in the laboratory. Digging up and growing mosses is typically not a news-worthy activity. The amazing thing about these mosses is that they had been buried in the permanently frozen ground (permafrost) for the last 1,500 years, since Roman times.
This story was covered by a variety of news sources. By far my favorite was Jennifer Frazier's coverage for National Geographic. She did a great job of discussing the science and soliciting comments from scientists doing similar research. For an audio clip of the story, I enjoyed the 60 second science podcast from Sophie Bushwick at Scientific American.
Let's put this study in perspective. Mosses can survive freezing. This is a known ability. Mosses are buried beneath the snow during winter in many places across the globe and each spring they thaw and resume growth. This study pushes our knowledge of this phenomenon to the extreme and leads to some questions.
How long can mosses survive frozen and recover? In the National Geographic article, Dr. LaFarge mentions that they have an upcoming study to test whether 50,000 year old mosses can resume growth. There will most definitely be more to come on this topic.
What are the compounds inside moss cells that act as antifreeze, helping them to prepare for and survive freezing? I know that I have read a paper on this somewhere. My memory says that they are called LEA proteins, but I can't recall which paper discussed them relating to mosses.
Can all species of mosses survive this long? Thinking ecologically, my guess would be that mosses from the tropics would not be able to survive frozen for even a single winter, let alone hundreds of years. Whereas, thinking systematically, the mosses that grew from 400 years ago (LaFarge et al 2013) were from four different moss families (Aulacomniaceae, Encalyptaceae, Ditrichaceae, Pottiaceae) and the one in this study is from a different family, the Dicranaceae. From this small sample it looks like surviving frozen for extended periods of time is a feature of many groups of mosses.
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| Figure S1 from Roads et al. 2014.Chorisodontium aciphyllum moss bank sampled in this study; (a) map of Signy Island indicating the study location; (b) coring the moss bank; (c) surface section of clearly separable gametophytes; (d) fresh-collected section of core from within the permafrost layer. |
This supplemental figure from the paper gives you a peek into some of the research methods. The upper right shows the researchers collecting mosses in the field. The lower right is a freshly collected core of mosses. It is amazing how compact the sample appears. It looks like a solid metal rod, but really the bottom left is a pulled-apart version of the bottom right.
I am looking forward to the next tale of zombie mosses from LaFarge and colleagues.
Can 50,000 year old mosses grow again?
