DNA repair

Did you Know???

There is a microbe that grows in the Dead Sea that is teaching scientists about the art of DNA repair.

Came across this article - Found it very interesting!!!

This microbe, called Halobacterium, may hold the key to protecting astronauts from one of the greatest threats they would face during a mission to Mars:  Space Radiation.  The harsh radiation of interplanetary space can penetrate astonauts' bodies, damaging the DNA in their cells, which can cause cancer and other illnesses.  DNA damage is also behind cancers that people suffer here on Earth.

Halobacterium appears to be a master of the complex art of DNA repair.  This mastery is what scientists want to learn from.

" We have completely fragmented their DNA.  I mean we have completely destroyed it by bombarding it with radiation.  And they can reassemble their entire chromosome and put it back in to working order within several hours"  says Adrienne Kish, member of the research group studying Halobacterium at the University of Maryland.

Being a virtuoso at repairing damaged DNA makes Halobacterium one hardy little microbe:  in experiments by Maryland research group, Halobacterium has survived normally-lethal doses of ultraviolet Radiation (UV), extreme dryness, and even the vacuum of space.

But why is Halobacterium such a tenacious survivor?  What caused it to evolve such dexterous DNA repair mechanisms?  And how do those mechanisms work?

Jocelyne DiRuggiero, leader of the Maryland research group, has been exploring these question for the last five years.  She believes the answer stems form the fact that Halobacterium naturally lives in some rater inhospitable places:  ultra-salty bodies of water such as the DEAD SEA.

Most sea live would quickly shrivel up and die in the Dead Sea's briny water, which is 10 times saltier than normal seawater.  The extreme saltiness damages an organism's cells, and especially the DNA inside those cells.  This happens because DNA molecules are accustomed to being surrounded by a dense swarm of water molecules, and DNA actually depends on the influence of these water molecules to keep its double-helix structures intact and to avoid damage.  but in ultra-salty waters, the dissolved salt crowds out the water molecules.  Partially deprived of the contact with water they need, the long strands of DNA  suffer damage and even break, causing the cell to malfunction or die.

Evolving to cope with a salty lifestyle could explain why Halobacterium is so good at surviving radiation and other ravages.

Halobacterium is something of a "Renaissance bug".  It dabbles in a bit of everything.  This genome of only 2400 genes contains several distinct sets of DNA-repair mechanisms.  Some of these sets of tools are like the DNA-repair tools found in plants and animals, other sets are more like those of bacteria, and still others are characteristic of a lesser-known group of lice called "Archaea"  (the group that Halobacterium belongs to).  Halobacterium has them all.
Beyond even that, Halobacterium has a few novel DNA-repair mechanisms that no one has ever seen before!!!

Wow, pretty amazing!!!


Extracts taken from:  First Science.com
6 January 2001
By Patrick L Barry.