Loading ...
Sorry, an error occurred while loading the content.

[evol-psych] Worm Shows Link Between Mutation And Behavior Change

Expand Messages
  • Ian Pitchford
    January 4, 2000 Worm Shows Link Between Mutation And Behavior Change A tiny transparent worm has enabled the first complete description of the biochemical
    Message 1 of 1 , Jan 4, 2000
    • 0 Attachment
      January 4, 2000
      Worm Shows Link Between Mutation And Behavior Change

      A tiny transparent worm has enabled the first complete description of the
      biochemical steps leading from a genetic mutation to a change in behavior,
      UT Southwestern Medical Center at Dallas investigators have reported.
      The understanding of the connection between genes and behavior at the
      molecular level is a major goal of neurobiology.

      "A question we want to answer in looking at the human genome is what
      controls behavior," said Dr. Leon Avery, associate professor of molecular
      biology at UT Southwestern and senior author of the paper. "I believe a lot
      of the genetics of human behavior will be understandable in molecular terms
      through a change in a single ion channel or single receptor molecule."

      The report appeared in the December 24th issue of Science.

      The researchers studied a worm called a c. elegans that had a mutation that
      affected its feeding behavior. They showed that the mutation in the gene
      exp-2 caused an abnormality in a potassium channel so that it remained open
      rather than opening and closing normally. This alteration prevented opening
      of the pharynx, the muscle used to eat.

      The opening of the potassium channel, called EXP-2, causes muscle
      relaxation. Normally the muscle relaxes a fifth of a second after
      contraction of the muscle. In the mutant worms, it relaxed in a 20th of a
      second after the contraction. This meant the muscle never contracted or
      opened all the way. The worms could not eat much because they could not
      take in adequate food.

      "A good way to imagine this is that the pharyngeal muscle is like a pump,
      pumping food into the worm," Avery said. "It works very much like a human
      heart. If a heart pumps too fast, it can't really pump any blood before it
      starts to relax again."

      Because the scientists were able to describe the biophysical,
      electrophysiological and behavioral effects of this mutation, they now know
      every step in the causal chain linking a mutation to altered feeding
      behavior in c. elegans. The researchers believe that studying such changes
      in molecules eventually may answer behavioral questions right down to why
      some people are cheerful and others are grumpy.

      The scientists also concluded from studying the worms' EXP-2 channel, which
      is related to the human potassium channel HERG, that these similarly
      functioning channels, although different in structure and sequence,
      apparently evolved to fill the same needs in different animals.

      The researchers now will try to determine if modifying the behavior of the
      EXP-2 channel also changes the worms' feeding behavior.

      The lead author of the study, Dr. M. Wayne Davis, recently earned his
      doctorate at UT Southwestern and is now at the University of Utah. Dr.
      Richard Fleischhauer, postdoctoral fellow, and Dr. Rolf Joho, associate
      professor of cell biology, both in the UT Southwestern Center for Basic
      Neuroscience, and Dr. Joseph Dent, assistant professor of biology at McGill
      University, Montreal, collaborated on the study.

      National Institutes of Health grants supported this research. - By Susan A.
    Your message has been successfully submitted and would be delivered to recipients shortly.