Science briefing: Simple cells for early life

Science briefing: Simple cells for early life
By Alan Cane
Published: June 6 2008 02:20 Last updated: June 6 2008 02:20
Simple cells for early life forms
The earliest living organisms – single, free-living cells – could have depended for their existence on structures that were very simple compared with the highly evolved structures we see today.
The cell membrane, for example, has sophisticated pumps, channels and pores for moving materials in and out of the cell. Researchers at Massachusetts General Hospital, writing in the journal Nature, say the most primitive cells made do with simple membranes of fatty acids. When these chemicals are concentrated in water, they assemble into membranes, which then close to form tiny spheres.
The researchers say such membranes would allow small molecules to enter the cell while large molecules, such as the genetic materials DNA and RNA, would be trapped. How these simple membranes evolved into today’s complex structures is unknown but it is clear the distinction between living and non-living was very fine when the world was young.
A hungry mob is an angry mob
Hungry individuals are often bad tempered and aggressive. Now scientists believe that it is not simple belligerence but follows a decline in serotonin, whose manufacture in the body depends on eating well and regularly.
Serotonin is one of the most important chemical messengers. It is made in the body from foods such as chicken soup and chocolate, which are rich in the chemical tryptophan (hence, some think, the “feel-good” factor associated with these foods). Serotonin levels are, inevitably, lower when someone is hungry.
Some kind of association between serotonin and behaviour had been suspected for some time but now Cambridge university scientists have the proof of the pudding, as it were, by persuading volunteers, both hungry and well-fed, to play a game that tests reactions to unfair behaviour. As the players’ serotonin levels fell, their ire rose at what they saw as unreasonable actions by their opponents.
Molly Crockett, one of the Cambridge team, said: “Our research suggests serotonin plays a critical role in social decision-making by normally keeping aggressive responses in check.” The result may help to explain illnesses associated with low serotonin levels such as depression and obsessive compulsive disorder. The work is reported in Science Express on Friday.
Car fumes could power the lights
Scientists across the world are seeking ways to turn waste heat from motor vehicles into power, to achieve lower carbon dioxide emissions and lower fuel consumption.
Researchers at the Fraunhofer Institute in Freiburg, Germany, are working on a thermoelectric generator to convert heat from car exhaust fumes into electricity. The Fraunhofer device depends on a temperature gradient: the greater the gradient, the more electricity generated.
Harald Böttner, head of the thermoelectric systems department, says exhaust gas temperatures can reach more than 700ºC, creating a steep gradient between gas and engine cooling fluid.
The thermoelectric convertor makes use of this differential to generate an electric current. This power source could, eventually, replace the alternator, responsible for a car’s electrical needs.
Mr Böttner says it could cut petrol consumption by between 5 and 7 per cent in an average car. The Fraunhofer researchers plan to build prototypes of their invention.