In subglacial lake, surprising life goes on: Team identifies species in most inhospitable realm

Jul 05, 2013
Schematic cross-section of Lake Vostok (above), drawn to scale (based on a radar study of Lake Vostok along the glacial flow line to the ice core drill site [2]) and metagenomic/metatranscriptomic summary (below). Credit: PLoS ONE 8(7): e67221. doi:10.1371/journal.pone.0067221

Lake Vostok, buried under a glacier in Antarctica, is so dark, deep and cold that scientists had considered it a possible model for other planets, a place where nothing could live.

However, work by Dr. Scott Rogers, a Bowling Green State University professor of biological sciences, and his colleagues has revealed a surprising variety of life forms living and reproducing in this most extreme of environments. A paper published June 26 in PLOS ONE details the thousands of species they identified through DNA and RNA sequencing.

"The bounds on what is habitable and what is not are changing," Rogers said.

This is the fourth article the group has published about its Lake Vostok investigations. The team included Dr. Paul Morris, biology, who with Scott and doctoral student Yury Shtarkman conducted most of the ; former doctoral students Zeynep Koçer, now with the Department of Infectious Diseases, Division of Virology, at St. Jude's Research Hospital in Memphis, performed most of the laboratory work; Ram Veerapaneni, now at BGSU Firelands, Tom D'Elia, now at Indian River State College in Florida, and undergraduate student Robyn Edgar, computer science.

Their work was supported by several grants, including two from the National Science Foundation, one from U.S. Department of Agriculture and one from the BGSU Faculty Research Committee. Together, the amount dedicated to the project was more than $250,000.

When thinking about Lake Vostok, you have to think big. The fourth-deepest on Earth, it is also the largest of the 400-some subglacial lakes known in Antarctica. The ice that has covered it for the past 15 million years is now more than two miles deep, creating tremendous pressure in the lake. Few nutrients are available. The lake lies far below sea level in a depression that formed 60 million years ago when the shifted and cracked. The weather there is so harsh and unpredictable that scientists visiting must have special gear and take survival training.

Not only had most scientists believed Lake Vostok completely inhospitable to life, some thought it might even be sterile.

Far from it, Rogers found. Working with core sections removed from the deep layer of ice that accreted from lake water that froze onto the bottom of the glacier where it meets the lake, Rogers examined ice as clear as diamonds that formed in the great pressure and relatively warm temperatures found at that depth. The team sampled cores from two areas of the lake, the southern main basin and near an embayment on the southwestern end of the lake.

"We found much more complexity than anyone thought," Rogers said. "It really shows the tenacity of life, and how organisms can survive in places where a couple dozen years ago we thought nothing could survive."

By sequencing the DNA and RNA from the accretion ice samples, the team identified thousands of bacteria, including some that are commonly found in the digestive systems of fish, crustaceans and annelid worms, in addition to fungi and two species of archaea, or single-celled organisms that tend to live in extreme environments. Other species they identified are associated with habitats of lake or ocean sediments. Psychrophiles, or organisms that live in extreme cold, were found, along with heat-loving thermophiles, which suggests the presence of hydrothermal vents deep in the lake. Rogers said the presence of marine and freshwater species supports the hypothesis that the lake once was connected to the ocean, and that the freshwater was deposited in the lake by the overriding glacier.

The largest number of species overall was found in the area near the embayment, including many that are common to freshwater environments, as well as marine species, psychrophiles and thermophiles. Numerous others were found that remain unidentified. The embayment appears to contain much of the biological activity in the lake.

"Many of the species we sequenced are what we would expect to find in a lake," Rogers said. "Most of the organisms appear to be aquatic (freshwater), and many are species that usually live in ocean or lake sediments."

For Shtarkman, who came to BGSU from St. Petersburg, Russia, the project has proven so engrossing that he foresees a possible lifetime of study around it. "It's a very challenging project and the more you study, the more you want to know," he said. "Every day you are discovering something new and that leads to more questions to be answered. In studying the environmental DNA and RNA, we ask how similar are these sequences to those of sequences from organisms already identified in national databases. We are tracing the evolution and the ecology of the lake itself.

Before 35 million years ago, Antarctica had a temperate climate and was inhabited by a diverse assemblage of plants and animals. About 34 million years ago, Rogers said, a "huge drop in temperature occurred" and ice covered the lake, when it was probably still connected to the Southern Ocean. This lowered sea level by about 300 feet, which could have cut off Lake Vostok from the ocean. The ice cover was intermittent until a second big plunge in temperature took place 14 million years ago, and sea level dropped even farther.

As the ice crept across the lake, it plunged the lake into total darkness and isolated it from the atmosphere, and led to increasing pressure in the lake from the weight of the glacier. While many species probably disappeared from the lake, many seem to have survived, as indicated by Rogers' results.

Rogers's group had worked for several years on identifying and studying organisms in the Vostok accretion ice using a procedure involving culturing colonies of bacteria and fungi, but the process was slow, especially for graduate students who needed results for their theses.

"We started thinking of doing it a different way," Rogers said.

Instead of culturing living organisms, they concentrated on sequencing DNA and RNA in the ice. These methods, called metagenomics and metatranscriptomics, produced thousands of sequences at a time that were then analyzed using computers—procedures referred to collectively as "Big Data" methods. In contrast, it usually took years to generate enough cultured organisms for a few dozen sequences.

The problem changed from having too few sequences to having too many sequences to analyze, Rogers said. After two years of computer analysis, the final results showed that Lake Vostok contains a diverse set of microbes, as well as some multicellular organisms.

Long before he began using metagenomics and metatranscriptomics to study the ice, Rogers and his team had developed a method to ensure purity. Sections of core ice were immersed in a sodium hypochlorite (bleach) solution, then rinsed three times with sterile water, removing an outer layer. Under strict sterile conditions, the remaining core ice was then melted, filtered and refrozen.

"Using this method, we can assure its reliability almost to 100 percent," Rogers said.

Eventually, the process rendered pellets of nucleic acids containing both DNA and RNA, able to be sequenced.

Rogers said the team erred strongly on the conservative side in reporting its results, including only those sequences of which it could be absolutely certain were from the accretion ice, but there are a multitude of others he feels are probably from the lake, opening the door to additional investigation.

The DNA sequences they produced have been deposited in the National Center for Biotechnology GenBank database, and will be available to other researchers for further study.

Explore further: Image: Towing the Costa Concordia

More information: Shtarkman YM, Koçer ZA, Edgar R, Veerapaneni RS, D'Elia T, et al. (2013) Subglacial Lake Vostok (Antarctica) Accretion Ice Contains a Diverse Set of Sequences from Aquatic, Marine and Sediment-Inhabiting Bacteria and Eukarya. PLoS ONE 8(7): e67221. doi:10.1371/journal.pone.0067221

Journal reference: PLoS ONE search and more info website

Provided by Bowling Green State University

4.9 /5 (12 votes)

Related Stories

Russia finds 'new bacteria' in Antarctic lake

Mar 07, 2013

Russian scientists believe they have found a wholly new type of bacteria in the mysterious subglacial Lake Vostok in Antarctica, the RIA Novosti news agency reported on Thursday.

CryoSat maps largest-ever flood beneath Antarctica

Jul 02, 2013

(Phys.org) —ESA's CryoSat satellite has found a vast crater in Antarctica's icy surface. Scientists believe the crater was left behind when a lake lying under about 3 km of ice suddenly drained.

Scientists drill two miles down to ancient Lake Vostok

Feb 13, 2012

(PhysOrg.com) -- Russian scientists last week finished penetrating more than two miles through the Antarctic ice sheet to Lake Vostok, a huge freshwater lake that has been buried under the ice for millions ...

Recommended for you

NASA sees Genevieve squeezed between 3 tropical systems

13 hours ago

The resurrected Tropical Depression Genevieve appears squeezed between three other developing areas of low pressure. Satellite data from NOAA and NASA continue to show a lot of tropical activity in the Eastern ...

User comments : 19

Adjust slider to filter visible comments by rank

Display comments: newest first

grondilu
5 / 5 (1) Jul 05, 2013
> which suggests the presence of hydrothermal vents deep in the lake.

Oh boy. Someone HAS TO check it out. James Cameron, are you reading this???
Torbjorn_Larsson_OM
5 / 5 (3) Jul 06, 2013
Most impressive is that they found a bivalve at 100 % sequence identity and two arthropods nearly as good. As for the fishes inferred from fish parasites, yes, they were quite a set so why not? The hydrothermal vent and the oxygen supplied with the ice would supply enough energy, we already know most of that from deep sea vents.

Europa looks more and more intriguing.
geokstr
1.7 / 5 (7) Jul 06, 2013
How can they be certain that there are no outlets to the ocean?
geokstr
1.7 / 5 (6) Jul 07, 2013
How can they be certain that there are no outlets to the ocean?

You know, it's really too bad that physorg took away the ability to see who rated comments.

I asked a simple, non-political, non-controversial question about the science, with no attacks on AGW or Obama or socialism, and not even an uncivil "-tard" style personal ad hominem against another commenter like most of the leftists do here, and managed to get to get two out of three "1"s for my prior "thoughtcrimes".

Not that I really give a rat's derriere about my ratings, but it does go to show that once a political opponent has been revealed to leftists, the hate-mongering begins on everything. And the new physorg accommodates your inner bully wannabe tendencies by allowing you to do it in total secrecy. Oh, the joy of it for you!

St Karl and Saul the Apostle would be proud. The only thing Orwell got wrong was the year.
JohnGee
1.6 / 5 (7) Jul 07, 2013
Lol, you think you live in Orwell's 1984 because some people on the internet are giving you " '1's " without you seeing who did it? I'm guessing you think Paula Deen is having her free speech rights violated, right? Your persecution complex is showing.

I asked a simple, non-political, non-controversial question about the science, with no attacks on AGW or Obama or socialism
This is NOT par for the course and I think you need to excuse people if they assume all your posts are total garbage. I've seen few exceptions.

Not that I really give a rat's derriere about my ratings
You just posted a 145 word essay-of-care on the subject. I bet it won't be the last time either.

PS: You can still see who rates your comments, you're just too stupid to find it. I'd tell you how but I don't want to rob you of the opportunity to bootstrap yourself to the solution.
Noumenon
1.5 / 5 (44) Jul 07, 2013
I asked a simple, non-political, non-controversial question about the science, with no attacks on AGW or Obama or socialism -geokstr
This is NOT par for the course and I think you need to excuse people if they assume all your posts are total garbage. - johndee


You're not excused. If you rate a comment you're expected to have read it, not to have made assumption of it. The comment ratings are not meant to express your general opinion about a poster either.

It's clear that because of your abuse of the comment rating system, and other troll raters like "open", "lite", "toot", "6of28", "NOM", etc, the last of which is actually associated with physorg somehow,... the rating system is faulty and should be disabled.
JohnGee
1.6 / 5 (7) Jul 07, 2013
If you rate a comment you're expected to have read it, not to have made assumption of it. The comment ratings are not meant to express your general opinion about a poster either.
You're making up rules like an 8-year-old that's about to lose a game of Monopoly. I will rate user's posts as I see fit.

That is all.
Noumenon
1.5 / 5 (44) Jul 07, 2013
An 8-year old would comprehend that the rules, as I have expressed them, are self evident in the given context, and would not attempt to argue to the contrary.
JohnGee
2 / 5 (4) Jul 08, 2013
They aren't your rules to express, so here are the rules:
http://phys.org/help/comments/

Your crybaby rating rule isn't in there. It would be pretty simple to enforce the rule--if it actually existed--so I'm fairly sure that's not the moderator's intent. You are astoundingly arrogant for someone who is so frequently and completely wrong.

I will rate user's posts as I see fit.

That is all.
Noumenon
1.4 / 5 (43) Jul 08, 2013
I will rate user's posts as I see fit.


How will you rate user's posts if you don't read them?
Noumenon
1.4 / 5 (43) Jul 08, 2013
They aren't your rules to express, so here are the rules:
http://phys.org/help/comments/

Your crybaby rating rule isn't in there. It would be pretty simple to enforce the rule--if it actually existed--so I'm fairly sure that's not the moderator's intent. You are astoundingly arrogant for someone who is so frequently and completely wrong.


I said the rules are self evident.

The rating controls are located next to each comment, so it stands to reason that they're to be used accordingly. How is it possible that this is ambiguous to you? Or do you think you can just lie yourself out of the hole you've dug.
JohnGee
1.8 / 5 (5) Jul 08, 2013
If your made up childish rules were correct, you would be required by the website's software to post in response before you could rate. QED.
Noumenon
1.5 / 5 (44) Jul 08, 2013
Wow, so "NOM", who is associated with the PhysOrg website, (can post without having any activity-page updated), actually rates me a 1 for the above post admonishing misuse of the rating system.

I guess that's why the rating system is not disabled,.. PhysOrg mods like to troll rate posters they don't like.
Noumenon
1.4 / 5 (43) Jul 08, 2013
If your made up childish rules were correct, you would be required by the website's software to post in response before you could rate. QED.


Only if the mods are competent with the web software, and set it up that way. I have requested all manner of such things to PhysOrg, to no avail.

Those rules are obvious and implicit given that the rating control is at each comment. But in your defense it is only obvious to 99.95%.
JohnGee
1.8 / 5 (5) Jul 08, 2013
Only if the mods are competent with the web software, and set it up that way. I have requested all manner of such things to PhysOrg, to no avail.
Are you autistic?

Those rules are obvious and implicit given that the rating control is at each comment.
How the hell else would there be rating of individual comments? You sound like a ufologist. (It hovered. UFO! It darted away. UFO! It flew backwards. UFO! There are rating controls on every comment even though there could be no other way of doing it. UFO!)
Noumenon
1.4 / 5 (43) Jul 08, 2013
Those rules are obvious and implicit given that the rating control is at each comment.


How the hell else would there be rating of individual comments?


Exactly, so know you understand that I did not invent any rules, and now you understand to read the comments before rating them.

Only if the mods are competent with the web software, and set it up that way. I have requested all manner of such things to PhysOrg, to no avail.


Are you autistic?

Huh?
JohnGee
1.8 / 5 (5) Jul 08, 2013
Now you are changing your crybaby rules. Wasn't it originally I had to comment if I disagreed? Tone down the histrionics and you may have an easier time making up your mind.

I will rate user's posts as I see fit.

That is all.
Noumenon
1.4 / 5 (43) Jul 08, 2013
Wasn't it originally I had to comment if I disagreed?


Nope, you just made that up. That would be a good idea, but I don't recall saying that in this thread. What started this silly banter was that you rated geokstr a 1 without reading his post and admitted having done so. Stay focused.
Gmr
1.7 / 5 (6) Jul 08, 2013
About the ice - I think there is some possibility expressed that some influx may have occurred -but given that it's 200 feet below sea level, outflow is less likely. In other words, we might find strangers, but any natives will be a few hundred thousand years unique at the outside.