Self-Made Cells Show Life Could Come From Space
Reuters
Jan 30 2001 12:19AM

WASHINGTON (Reuters) - Tiny little bubbles that can build themselves in the freezing vacuum of space suggest that life, or the seeds of life, could have originated out in the cosmos, scientists say.  In an experiment that duplicated the harsh conditions of space -- cold temperatures, no air, plenty of radiation -- they managed to get artificial cell membranes to form.

The membranes, which resemble soap bubbles, could act as primitive cell walls, David Deamer, a biologist who specializes in membranes at the University of California Santa Cruz, said Monday in a telephone interview.  "This wall is semi-permeable. All membranes are semi-permeable, so that things like water and oxygen get in and out very easily," said Deamer, who worked on the study. "That is what life requires -- it needs to have an inside that is not totally shut off from the outside."  Writing in Tuesday's issue of the Proceedings of the National Academy of Sciences, the researchers said organic compounds from interstellar space might have kick-started life on Earth.
Deamer said the compounds have been found on dust from meteorites carried to Earth, and years ago these compounds were found to "self-assemble" into soapy, water-repelling bubbles.  When the U.S. space agency NASA started its astrobiology program -- a search for life in space -- researchers teamed up to see what it would take to make a cell in space.
"Scientists believe the molecules needed to make a cell's membrane, and thus for the origin of life, are all over space," Louis Allamandola of NASA's Ames Research Center in California, who led the study, said in a statement.  "This discovery implies that life could be everywhere in the universe."
SIMPLE, COMMON COMPOUNDS

The researchers used simple, common compounds, which self-assembled into
something that looked very much like a vesicle or cell membrane.  "This process happens all the time in the dense molecular clouds of space," Allamandola said.  Such compounds could easily have been brought to Earth by a meteorite or asteroid. "The delivery of these compounds could well have been critical to the origin of life on Earth," Allamandola said.  "Maybe these molecules were just the raw lumber lying around that allowed origin-of-life chemicals to move in and set up housekeeping or construct their own houses," added Jason Dworkin, a post-graduate researcher at NASA who did much of the work on the study.

The next step is to see if these little bubbles can support cell-like activity inside and Deamer said they might.  "We are trying on purpose to put things like DNA and RNA inside the vesicles," he said.  DNA and RNA are the genetic basis of life, with DNA carrying the basic instructions for cellular activity and RNA carrying it out.  "In a sense we are trying to make, not an artificial form of life because we are nowhere near this, but a model of what would have led to early life,"  Deamer said.  "We have captured a gene on DNA in a little lipid (fatlike) vesicle. We also captured an enzyme that can use that gene to make RNA. That's all inside a little cellular vesicle."  They are feeding it with chemicals known to support cell activity and so
far it is working, he said.