Today, Mars is barren and lifeless; it is believed that it may once have been inhabited by organisms that share a common ancestor with those on earth. New evidence is emerging to support the hypothesis that life existed on Mars. This includes the discovery of methane gas which is produced by some terrestrial microbes and this has led scientists to hypothesise that life still may be present just below the surface. In order to gain concrete evidence for life on Mars, Gary Ruvkun and colleagues plan to send a DNA sequenc
er to Mars to look for traces of DNA that may be present in the Martian soil and subsequently sequence them. The Martian environment may have been different to its present rocky and barren state and thus would have been able to support forms of life.
Some researchers believe that if life was present on Mars, then those organisms would have shared an evolutionary past with organisms that are present on Earth today. This hypothesis is based on the fact that when the solar system was formed, rock bodies that collided with planets may have been energetic enough to displace fragments between planets. These fragments may have carried with them ancient forms of life which blossomed on Earth and Mars.
To find and sequence DNA on Mars’ surface, an automatic DNA sequencer will be sent to Mars. This automatic sequencer will be able to gather samples of soil and ice and detect whether DNA fragments are present by marking them with fluorescent dyes. If small amounts of DNA are found, then the polymerase chain reaction will be employed in order to obtain a large enough sample to make the sequencing process more efficient and accurate. To determine evolutionary links between Martian and terrestrial organisms, researchers will look for a similarity in the DNA sequence which encodes for the 16S ribosomal RNA. This rRNA is an integral part of ribosomes in the cell and hence has not mutated or evolved over the generations.
Although the DNA sequencer has already been tested on earth with conditions similar to those on Mars, there is scepticism about the viability and validity of these tests. Although, sequencing Martian DNA would be the ultimate proof for life on Mars, some scientists believe other, broader tests should be carried out before attempts are made to find and sequence DNA. The future of this exciting new project rests now on obtaining funding grants and further improving the technique and only time will tell whether Ruvkun and colleagues are successful in finding traces of life on Mars.
Reference: http://www.newscientist.com/article/dn16933-dna-analysis-may-be-done-on-mars-for-first-time.html
