"Bad news for the 220-mile high club: Researchers find sex in space could lead to life-threatening illnesses"
Experiments on plants showed changes in gravity damages cells.
Researchers say findings could have major implications for human health.
Scientists say zero gravity affects processes involved in reproduction, brain diseases - and even cancer.
March 13th, 2013
Space tourists hoping to join the '220-mile high club' have been brought back to Earth by new research showing sex in space wrecks health.
Experiments on plants show changes in gravity damages cells - and could lead to life-threatening illnesses.
Rumours have abounded for over a decade astronauts have already done the deed although NASA and the Russian government has denied these.
Now scientists say zero gravity affects processes involved in reproduction, brain diseases - and even cancer.
A study found gravity modulates cell 'highway traffic' that ensures the growth and functionality of the male reproductive organ in plants - the pollen tube.
Professor Anja Geitmann, a biologist at Montreal University, said: 'Just like during human reproduction the sperm cells in plants are delivered to the egg by a cylindrical tool.
'Unlike the delivery tool in animals the device used during plant sex consists of a single cell - and only two sperm cells are discharged during each delivery event.
'Our findings offer new insight into how life evolved on Earth and are significant with regards to human health, as a traffic jam on these highways that also exist in human cells can cause cancer and illnesses such as Alzheimer's.'
The interior of animal and plant cells is like a city, with factories called organelles - dedicated to manufacturing, energy production and waste processing.
A network of intracellular 'highways' enables the communication between these factories and the delivery of cargo between them and between the inside of the cell and its external environment. Plant cells have a particularly busy highway system.
Professor Geitmann, whose study is published in PLOS ONE, said: 'Researchers already knew humans, animals and plants have evolved in response to Earth's gravity and they are able to sense it.
'What we are still discovering is how the processes occurring within the cells of the human and plant bodies are affected by the more intense gravity, or hypergravity, that would be found on a large planet, or the microgravity that resembles the conditions on a space craft.
'Intracellular transport processes are particularly sensitive to disturbance, with dramatic consequences for cell functioning. How these processes are affected by a change in gravity is poorly understood.'
In the tests plant cells were placed into a large centrifuge along with a camera attached to a microscope enabling the researchers to track in real time how they develop in the intense gravity generated by the machine.
Co-researcher Dr Youssef Chebli said: 'Thanks to the facilities at the European Space Agency I was able to determine how hypergravity and simulated microgravity affect the intracellular trafficking in the rapidly growing pollen tube.
'We chose pollen - the carrier of the male sperm cells - as our model because of its pivotal role in plant reproduction and agriculture and because of its extraordinarily rapid growth, meaning we could observe the effects of the hypergravity within seconds.'
The researchers stained specific structures within the cells which revealed how the components move around and how the cellular transport logistics responds to the changing gravity environment.
Dr Chebli said: 'We found intracellular traffic flow is compromised under hyper-gravity conditions and both hyper and microgravity affect the precisely coordinated construction of the cellular envelope in the growing cell.
'This allows us not only to understand general principles of the reproductive mechanism in plants but, more importantly, how the intracellular transport machinery in eukaryotic cells responds to altered gravity conditions.
'Our findings have implications for human health as similar effects are likely to occur in human cells such as neurons where long distance intracellular transport is crucial.'
While humans have been a spacefaring species for over 50 years it's doubtful we've yet performed the most basic of acts despite the introduction of mixed-gender crews in 1983.
NASA doesn't explicitly forbid sex while zipping round Earth at 17,500 mph but its code of conduct calls for "relationships of trust" and "professional standards" to be maintained at all times.
But sex in space will happen eventually because manned missions to Mars would last years so abstinence for that long would be a tall order for most people.
And sex would likely be a natural part of life at a lunar or Mars base - especially if the aim is to one day establish a self-sustaining colony.
The rise of private spaceflight should open the door even more to sex in space.
Virgin Galactic hopes to start flying tourists to suborbital space next year.
It has already turned down a $1 million offer from an unidentified party to aid in the production of a sex-in-space movie.
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