Cool Place of the Week #9- Lake Vostok, Antartica

Picture from this article.

Lake Vostok is one of about 150  subglacial lakes located in Antarctica. It is covered by over 2 miles of ice. Scientists have been trying to drill through the ice to the lake since 1998- the project has been plagued by funding shortages, equipment failures and harsh environmental condtitions (we're talking temperatures hitting -128 degrees Fahrenheit). Another big issue that slowed the project was the possibility of contaminating Lake Vostok with drilling fluids (kerosene and Freon), which has been isolated for millions of years (between 15 and 34 million years).  It is quite possible that the lake contains new life forms unknown to science. On the other hand, it's possible that the lake is devoid of life, due to its super high oxygen levels. Even if that were the case, that would make Lake Vostok the first water body on Earth to contain no life.

Russian scientists have confirmed a few days ago that they have successfully reached the lake, just before being forced to pack up for the harsh Antarctic winter.

I am really excited to see what is found. This is ground breaking science here, having possible implications for extraterrestrial life It goes without saying that I will be sure to keep you posted on any developments!


Contributing articles from: The New York Times and The Week.

An Update on "An Unusual Bacteria"

Last week I wrote an article ("An Unusual Bacteria") about a potentially ground breaking finding that a bacterium had been found to be using arsenic in its DNA structure. A few days ago I came across an article in Scientific American about a follow up study that was performed.

The follow up study grew the bacteria , GFAJ-1, in arsenic and very little phosphorus, like the methods used in the original paper. The DNA of the grown bacteria was then purified and sent off for analysis using a caesium chloride gradient and then a mass spectrometer. The results showed that no arsenic was found in the DNA.

However, these results have yet to be published in a peer-reviewed scientific paper, so this new finding must be taken with a grain of salt. The author of the original paper about GFAJ-1, Felisa Wolfe-Simon, countered that perhaps the caesium chloride gradient made any arsenic-containing DNA too fragile, and broke apart, and not appearing in a significant way in the results. Also, it could be argued that the follow up study did not starve the bacteria of enough phosphorus so that it would start using arsenic.

An Unusual Bacteria

Mono Lake in California is not your traditional lake; it is in what's known as an endorheic basin, meaning that there is no outflow of water from the lake to the ocean. As a result, Mono Lake has accumulated a lot of dissolved salts and is very alkaline; it is also naturally high in arsenic. Despite those harsh conditions, Mono Lake is thriving with life, and is also an important stop over for migratory birds.

A paper was published in December 2011(here is a link to the paper) about a potentially unique strain of bacteria found in Mono Lake. The bacteria, called GFAJ-1 (I read in an article a while back that it stands for "Give Felisa A Job," Felisa, being the lead researcher. I can't find the original article that says that though) not only survives in an enviornment with high arsenic levels, but is also thought to utilize arsenic into its DNA structure. You know, arsenic, the toxic heavy metal? Wait a second....

Transmission electron micrograph of the bacterium

 GFAJ-1.  Credit: Science/AAAS.

What the research team proposed is that this bacteria is using arsenic in its DNA instead of phosphorus. On a strictly structural basis, this would be possible for a few reasons- Both arsenic and phosphorus are in the same column of the periodic table and thus have the same number of valence electrons, meaning that they both can make the same number of bonds. Arsenic and phosphorus also have similar atomic radii. And it turns out that they both have almost the same electronegativity (arsenic is 2.18 and phosphorus is 2.19) which is just a fancy term for the affinity of an atom to attract electrons (and thus make bonds). However they have different ionization energies (the energy required to remove an electron), though in comparison to the other elements, the two are rather close.

The research team brought the bacteria back to the lab, and did some experiments growing the bacteria in a phosphorus limited environment (no added phosphorus, only what was originally present in the samples), and found that GFAJ-1 grew fine- that the arsenic was definitely not impeding the growth. The team also did experiments to find evidence that GFAJ-1 was actually incorporating the arsenic into its own biomolecules, by tracing radioactive arsenic. The results indicated that GFAJ-1 was actually using the arsenic in its DNA.

This finding rocked the scientific world, because it was a generally accepted fact that the elements necessary for life included carbon, hydrogen, oxygen, nitrogen, phosphorus,and sulfur. So to find that an organism was using arsenic instead of phosphorus was has huge implications for understanding different life forms, both here on Earth and in space. Perhaps there are other instances of elemental substitution that make life possible on other planets?

As with any radical idea, this finding has its critics. There is a lot of skepticism about how the samples were analyzed and the conclusions of the research team. It's an interesting find nonetheless, and I look forward to seeing what further research has to find on the idea!