Showing posts with label science fiction. Show all posts
Showing posts with label science fiction. Show all posts

Monday, 21 January 2013

Lost in Space

Astronauts may risk Alzheimer's

Astronauts May Risk Alzheimer’s - London Student
21 Jan 2013 | News and Features
Written by Helga Groll
It may sound like science fiction, but ‘Space Tourism’ is already here, and a recent study suggests such trips to space could be harmful to our brains.
Outside the Earth’s protective atmosphere, cosmic radiation has been found to produce a variety of health effects, from increased risk of cancer and cardiovascular disorders to the weakening of the immune system. These might not be the only issues though. A recent study suggests that astronauts could also be more prone to suffering from Alzheimer’s disease. Researchers exposed mice to radiation comparable to the amount astronauts would experience on a mission to Mars. The scientists found that memory was impaired and protein plaques had formed in the brain. These plaques are characteristic in those with Alzheimer’s; they alter or stop the communication between nerve cells, which leads to cognitive impairment. Although this study highlights possible non-anticipated dangers for astronauts, it is too early to be fully aware of the risks to humans of space travel.
The research only looked at very few mice, and exclusively males were studied. The mice were also genetically modified in a way that made them predisposed to developing Alzheimer’s disease. This means they had genes that increased their susceptibility to getting the disease, although they should still have remained healthy under normal circumstances. M. Kerry O’Banion, Professor of Neurobiology and Anatomy at the University of Rochester stated: “the mice tended to show plaque pathology starting at 5 to 6 months of age. Our results could indicate that environmental stimuli can influence Alzheimer’s pathology, at least in a mouse model.”
The problem is that the scientists can’t be certain whether the decrease in cognitive function was caused by radiation alone, or because of a combination of radiation and gene mutation. It is also unclear how long astronauts would need to be exposed to the radiation to suffer from health effects. “The dose duration was very different for mice and astronauts. Thus we cannot draw a simple conclusion yet” Professor O’Banion added.

While space tourism might remain science fiction for most of us (an 8 day trip costs around $20 million USD), it is important to minimise the risks for astronauts or space tourists by developing better radiation shielding for the space crafts. 44 years after the infamous “one small step for man, one giant leap for mankind”, we certainly have come far in our exploration of space. Perhaps at this point we should consider exploring our own planet Earth for a while longer. Five billion years have shaped this planet into its current form, and it is perfectly adapted to risks such as cosmic radiation. We owe it to ourselves and future generations to do our best to conserve it. After all, despite our desire to find new worlds to explore, mother Earth may be the only liveable planet accessible to us for a long time.

Monday, 19 November 2012

Test Tube Dinosaurs

Will Jurassic Park become reality?

Test Tube Dinosaurs? - London Student
19 Nov 2012 | News and Features
Written by Helga Groll
Dinosaurs, the giant primeval beasts, have fascinated old and young for generations. Michael Crichton and Steven Spielberg’s Jurassic Park has inspired fantasies that we might one day see these prehistoric creatures in real life. In the movie, scientists used dinosaur blood from the stomachs of fossilised parasitic insects that were once sucking on T-rex and Co to extract DNA and bring the fearsome reptiles back to life.
Recent studies have investigated how plausible this DNA preservation and extraction could be. An Australian research team used buried Moa bones to conclude that DNA would not survive longer than 6.8 million years. A pretty impressive time span, however dinosaurs first appeared around 230 millions of years ago, and died out almost 70 million years ago.
The international research group examined 150 leg bones of the Moa, a giant extinct bird. The bones ranged between about 600 and 8,000 years old and were collected from three different sites. Palaeo-geneticists led by Morten Allentoft at the University of Copenhagen and Michael Bunce at Murdoch University in Perth, Australia found the half-life of DNA to be 521 years. This meant that after 521 years, half of the bonds in DNA had degraded, leaving half of the genetic information unreadable.
DNA has a limited ‘life span’ or, more accurately, chemical stability. Without the repair mechanisms present in a living cell, DNA decays and is eaten by micro-organisms. After 6.8 million years, the DNA would be completely destroyed. This makes finding intact DNA from more than 100 million years ago, the ‘prime time’ of dinosaurs, very unlikely. As for DNA long enough to be sequenced in a lab and studied, Dr Allenthoft says “such fragments will be gone long before the 6.8 million year mark”. Such a result would shatter hopes that we will be buying our tickets to a real Jurassic Park in the near future.
However, another recent study of ancient bones suggests there could be a twist in the story. The team analysed bones cells (osteocytes) of two dinosaurs, Tyrannosaurus rex and Brachylophosaurus canadensis. They claim to have found remnants of osteocytes, which could contain DNA. These remains are yet to be verified; and even if the cells contained DNA there may not be enough left to confirm its origin. Osteocytes are comparatively ‘invincible’ and cannot be destroyed and could be preserved in ancient tissue.
Dr Mary H Schweitzer, lead author of the study criticised the previous study, stating that “These authors did not test fossils dating back older, rather predicted that DNA would be gone by a certain time point”. She adds that her bone samples do not agree with this hypothesis; “We have 4 independent lines of evidence that there is material chemically consistent with DNA”
Even if DNA remains in these dinosaur bones, the slow degradation over time may mean not enough remains to study the genetic information of the animals through genetic sequencing. “We can’t demonstrate that the reactive material inside these dinosaur ‘cells’ is dinosaur DNA without sequence.”

So where does that leave Jurassic Park? For long strands of DNA to have any chance of surviving a 65 million year wait to the modern day, they would require perfect conditions. So could there be an untouched, perfectly preserved dinosaur genome under the Earth waiting to be discovered? “I would not completely dismiss the idea that that DNA can survive longer than we think under some extreme and rare conditions” explains Dr. Allenthoft, “but at the moment there is nothing suggesting that we will ever get authentic DNA from dinosaur bones”.