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Science

Multicellular Life Evolves In Months, In a Lab 285

Posted by Soulskill
from the selecting-for-extroverted-cells dept.
ananyo writes "The origin of multicellular life, one of the most important developments in Earth's history, could have occurred with surprising speed, U.S. researchers have shown. In the lab, a single-celled yeast (Saccharomyces cerevisiae) took less than 60 days to evolve into many-celled clusters that behaved as individuals. The clusters even developed a primitive division of labor, with some cells dying so that others could grow and reproduce. Multicellular life has evolved independently at least 25 times, but these transitions are so ancient that they have been hard to study. The researchers wanted to see if they could evolve multicellularity in a single-celled organism, using gravity as the selective pressure. In a tube of liquid, clusters of yeast cells settle at the bottom more quickly than single cells. By culturing only the cells that sank, they selected for those that stick together. After many rounds of selection over 60 days, the yeast had evolved into 'snowflakes' comprising dozens of cells."
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Multicellular Life Evolves In Months, In a Lab

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  • by Anonymous Coward on Tuesday January 17, 2012 @11:00PM (#38733946)
    This is likely just re-emergence of previously evolved and currently dormant behavior.
  • by damn_registrars (1103043) <damn.registrars@gmail.com> on Tuesday January 17, 2012 @11:04PM (#38733976) Homepage Journal
    Experimental evolution of multicellularity [pnas.org]

    And PNAS has it listed as open access, which means you should be able to download the full text regardless of your subscriber (or non-subscriber) status. Just click the Full Text link.
  • by Anonymous Coward on Tuesday January 17, 2012 @11:15PM (#38734044)

    Also mentioned in tfa. The scientist says that he plans to do an experiment with organisms without multicellular ancestors.

  • by Samantha Wright (1324923) on Tuesday January 17, 2012 @11:21PM (#38734076) Homepage Journal
    That's a big question! We currently believe that the circumstances that created life were pretty harsh in some respects and extremely mild in others. There are a number of different ideas floating around [wikipedia.org], including the proverbial primordial soup, clouds of space dust (panspermia), and a boiling puddle of fat. Most likely, the conditions that were on Earth billions of years ago (a hot boiling hell with a mostly hydrogen atmosphere, amongst other things) contributed substantially to the factors that led to life's rise.
  • Flocculation (Score:3, Informative)

    by Wookie Monster (605020) on Tuesday January 17, 2012 @11:22PM (#38734086)
    Yeast already has a natural ability to flocculate, differing by strain. All they did is use artificial selection to produce a new strain of yeast with higher flocculation. The article mentions that yeast evolved from a multicellular life form and that the next experiment will use single celled organisms which did not evolve this way. I suspect it will take much longer than 60 days to see any results.
  • by wisebabo (638845) on Tuesday January 17, 2012 @11:28PM (#38734132) Journal

    Not to diminish the importance of multi-cellularity (and of this discovery) but wasn't the development of Eukaryotes (cells with Nuclei and other differentiated organelles) the big step needed for complex life? I mean with chloroplasts you get plants and mitochondria (or mitoklorines for you Star Wars fans) you get animals.

    With multi-cellularity and prokaryotes you get strombolites (algal mats).

    That said, it shows that evolution can happen quite quickly and can overcome some serious obstacles in a short amount of time in a very limited scope (a laboratory workbench). When multiplied by geologic ages and oceans of room is it any wonder that life has evolved in so many fascinating ways?

  • by Samantha Wright (1324923) on Tuesday January 17, 2012 @11:35PM (#38734168) Homepage Journal
    Yeah... But! There are plenty of fancy single-celled eukaryotes that are fantastically dull. Multicellular life is still a pretty neat thing. You just wait; give molecular biology enough time and we'll see experiments that recreate the emergence of eukaryotes, animals, chordates, mammals, primates, hominids, and finally molecular biologists. Just give 'em time.
  • by Samantha Wright (1324923) on Tuesday January 17, 2012 @11:39PM (#38734194) Homepage Journal
    This has indeed been pondered! We're pretty sure that all life that presently exists all comes from one root, however. If there ever were alternative life-starting events, they didn't survive. The reason for this is that all extant organisms share a number of completely arbitrary decisions called chirality [wikipedia.org] (if you know any physics, that's left-handed vs. right-handed molecular symmetry.) Chirality is completely random in the chemical reactions that produce amino acids and nucleotides, but absolutely fixed, in the same way, in every living organism we've studied. A number of environmental tests have been conducted specifically to look for organisms of contrary chirality, but we haven't found anything yet.
  • by Anonymous Coward on Tuesday January 17, 2012 @11:42PM (#38734208)

    This was on RichardDawkins.net back in June, and in the version of the article linked there, there were these telling paragraphs:

    Sceptics, however, point out that many yeast strains naturally form colonies, and that their ancestors were multicellular tens or hundreds of millions of years ago. As a result, they may have retained some evolved mechanisms for cell adhesion and programmed cell death, effectively stacking the deck in favour of Ratcliff's experiment.

    "I bet that yeast, having once been multicellular, never lost it completely," says Neil Blackstone, an evolutionary biologist at Northern Illinois University in DeKalb. "I don't think if you took something that had never been multicellular you would get it so quickly."

  • by airuck (300354) on Wednesday January 18, 2012 @12:17AM (#38734392)

    10 yeast cells clumped together have more mass than 1 yeast cell. Therefore they sink to the bottom of a tube.

    Bzzt. Please review the difference between mass and density and the relationship between density and buoyancy.

  • by Eskarel (565631) on Wednesday January 18, 2012 @12:26AM (#38734430)

    The summary is true, but ultimately misleading.

    This is evolution, and it did happen in months. What it doesn't account for is getting the clumping gene in the first place, and that the likelihood of getting selection pressures as extreme as the ones in the lab is fairly low.

    They've proven that yeast has the capacity to evolve in this way given the right selection pressures, which is interesting. With additional research they may be able to prove that many other single celled life forms have the same capacity, from which we may extrapolate that the gene responsible for this behavior either occurred very early or is a relatively minor mutation.

    The "more quickly than we believed" part is probably bogus. They applied extreme selection pressures to this particular colony of yeast and so they got an extreme time scale result the same would happen in any species if you extrapolated for the length of a given generation. You could do the same thing to humans for some arbitrary characteristic.

  • by koekepeer (197127) on Wednesday January 18, 2012 @12:54AM (#38734556)

    IIRC from the times when I used yeast in my PhD research, wild type (that means: not mutated) S. cerevisiae clumps in advanced stationary phase (end of growth curve, nutritional deprivation). Such circumstances happen more often that not in the real life of S. cerevisae: just imagine that in nature it cannot walk to the nearest grapevine and say 'hey lets do some sugar fermentation here'... no it depends on being able to survive in times of drought. ne way it does that is through forming spores, another way of temporarily surviving could be this kind of 'clumping'. So, the 'clumping gene' is already there, it is just expressed in certain circumstances, circumstances easily simulated in a lab situation.

    In my mind the argument would revolve around self-organisation versus (old, dormant) organisational information still present in the S. cerevisae genome. I'm bummed I cannot access the original article at the PNAS site, else I could comment on that in a bit more detail.

  • by Samantha Wright (1324923) on Wednesday January 18, 2012 @02:15AM (#38734980) Homepage Journal
    Yep. It's called endosymbiotic theory. For a while it was just a crazy idea, but we're pretty sure we know exactly what kind of bacterium it came from (purple and green sulphur bacteria for mitochondria and chloroplasts, respectively.) Another name for it might be "yet another blatant dagger in the back of intelligent design," but genomics is a treasure trove of those on any day.
  • by Xoltri (1052470) on Wednesday January 18, 2012 @12:05PM (#38738728)
    No, fermentation to produce alcohol is completely anaerobic regardless of if it is an ale or a lager. There is an initial aerobic phase that the yeast use to reproduce, but once the dissolved oxygen is used up they start the good kind of fermentation, the kind that makes alcohol and co2. Furthermore, I'm not sure what date to assign to when "God got his driving license", however according to Wikipedia lager yeast (otherwise known as bottom fermenting) dates back only till the 1400's.

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