Friday, June 12, 2015

How much DNA is there on Earth?

Scimex: In a UK study that would put Sesame Street's Count to shame, researchers have attempted to measure the total sum of DNA on Earth. The authors found the final number to be in the 50 trillion trillion trillions (5 followed by 37 zeros), and say that the study can now lead to new research opportunities about life on Earth. The first study to count the sum total of all DNA everywhere on Earth – in the cells of plants, animals and tiny organisms such as bacteria – estimates that it weighs about 50 billion tonnes; enough to fill one billion shipping containers. This is equivalent to 50 trillion trillion trillion (5 followed by 37 zeros) of the fundamental chemical "letters" – known as base pairs – that allow DNA to encode genetic information.

The authors say that their study, which publishes on June 11th in the Open Access journal PLOS Biology, gives a new perspective on Earth's biodiversity, by enabling comparisons between various groups of organisms. They suggest that it could provide a fresh approach to conservation planning and policymaking.
The researchers, based at the University of Edinburgh, used available data on the genetics of various species and their populations to make the first estimate of the amount of DNA present in plants and animals. They also researched DNA data for other forms of life including bacteria and fungi – which include some of the most populous organisms on Earth.
To store the information contained in the biosphere's DNA you would need a billion trillion of the world's most powerful supercomputers (1 followed by 21 zeros). And as all the cells on the planet use that information by transcribing their genes from DNA to RNA, the authors estimate that they use a total processing power greatly exceeding a trillion trillion operations per second.
Aside from highlighting these spectacular computational properties of life on Earth, the authors hope their approach might enable the targeting of geographical regions or habitats that may be more important than others for preserving biodiversity, which could be useful as a complementary method to assist prioritizing and assessing conservation efforts.
They say that their study has revealed opportunities for new research about life on Earth, such as a better understanding of the density of organisms in various environments, and how genome sizes and chromosome levels differ across kingdoms. They emphasise that this study represents an initial estimate, and expect that their calculations can be refined as more information becomes available.
Hanna Landenmark of the School of Physics and Astronomy, University of Edinburgh – one of the authors of the article – said: "This preliminary estimate could potentially provide an additional way to quantify natural and anthropogenic processes and changes in the biosphere, which can inform conservation efforts and assessments of habitat and diversity loss."
Another author, Professor Charles Cockell, added: "This offers a way to look at the total information content of the biosphere and how it's changed over time, rather than just focusing biodiversity assessments on the number and types of species."