Skip to comments.Tough Earth bug may be from Mars
Posted on 09/26/2002 3:12:44 PM PDT by Heartlander
Tough Earth bug may be from Mars
19:00 25 September 02
Exclusive from New Scientist Print Edition
A hardy microbe that can withstand huge doses of radiation could have evolved this ability on Mars.
That is the conclusion of Russian scientists who say it would take far longer than life has existed here for the bug to evolve that ability in Earth's clement conditions. They suggest the harsher environment of Mars makes it a more likely birthplace.
The hardy bugs could have traveled to Earth on pieces of rock that were blasted into space by an impacting asteroid and fell to Earth as meteorites.
Deinococcus radiodurans is renowned for its resistance to radiation - it can survive several thousand times the lethal dose for humans. To investigate how the trait might have evolved, Anatoli Pavlov and his colleagues from the Ioffe Physico-Technical Institute in St Petersburg tried to induce it in E. coli.
99.9 per cent deadly
They blasted the bugs with enough gamma rays to kill 99.9 per cent of them, let the survivors recover, and then repeated the process. During the first cycle just a hundredth of the lethal human dose was enough to wipe out 99.9 per cent of the bacteria, but after 44 cycles it took 50 times that initial level to kill the same proportion.
However, the researchers calculate that it would take thousands of such cycles before the E. coli were as hardy as Deinococcus. And on Earth it would take between a million and a hundred million years to accumulate each dose, during which time the bugs would have to be dormant.
Since life originated on Earth about 3.8 billion years ago, Pavlov does not believe that there has been enough time for this resistance to evolve.
On Mars, however, the researchers calculate that dormant bugs could receive the necessary dose in just a few hundred thousand years, because radiation levels there are much higher.
What is more, they point out that the Red Planet wobbles on its rotation axis, producing a regular cycle of climate swings that would drive bacteria into dormancy for long enough to accumulate such doses, before higher temperatures enabled the survivors to recover and multiply. Pavlov reported the results last week at the Second European Workshop on Astrobiology in Graz, Austria.
David Morrison of NASA's Astrobiology Institute is sceptical that Deinococcus came from Mars, pointing out that its genome looks similar to those of other Earthly bacteria. But he admits that there's still no obvious explanation for the bug's resistance to radiation.
"It is certainly a mystery how this trait has developed and why it persists," he says.
Spider mite upsets evolutionary theory
They were bugs before and they're bugs now. Micro-evolution bump. ; * )
Time flies when youre havin fun and fruit flies like bananas.
And why should it. The ability to develop genetic immunity to antibiotics was developed to survive chemical attacks BY OTHER BACTERIA. After all, that is all that antibiotics are--chemicals developed by bacteria that are fatal to other bacteria. In other words "..bacterias antbiotic fighting arsenal" actually arose in response to ANCIENT antibiotics.
Thanks for proving my point. You have moved from actual laboratory demonstration to just-so stories.
Typical brain-dead creationist response. Try looking at a petri dish. That ability is exactly how they TEST FOR BIOLIOGICAL ACTIVITY. Chemical attack is the mode of action in the single-celled world, the ability to quickly adapt to such an attack is well-documented, and by no means "just-so stories". But then, you wouldn't know about that, would you.
How about cobalt thorium G?
Also demonstrating the Darwininians typical response.
Indeed. This would easily be kept in a volume no more than 370,000 times the volume of the observable universe.
Knock yourself out!
I don't remember the decay schemes exactly, but if you start with a large nuclei like uranium, it'll run through a lot of the smaller, more radioactive species like cobalt as it decays into other elements. A lot of the really radioactive elements are so short-lived that they only occur when they decay from something else.
Think of the pooper-scooper you'd need to clean that up.