[Paleopsych] Live Science: Human Gene Changes Color of Fish

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Human Gene Changes Color of Fish
http://www.livescience.com/animalworld/051215_fish_color.html
[No bawling about the dangers of racism here, either.]

    By [33]Bjorn Carey
    LiveScience Staff Writer
    posted: 15 December 2005
    02:05 pm ET

    Scientists have changed mutated, golden-colored zebrafish to a standard
    dark-striped, yellowish-white variety by inserting the genetic information 
for
    normal pigmentation into young fish.

    In an interesting twist, they also found that inserting a similar human 
version
    of the pigment gene [34]resulted in the same color change.

    As with humans, zebrafish skin color is determined by pigment cells, which
    contain pigment granules called melanosomes. The number, size and darkness 
of
    melanosomes per pigment cell influence the color of skin.

    For example, people of European descent have fewer, smaller, and lighter
    melanosomes than people of West African ancestry, and Asians fall somewhere 
in
    between.

    The golden zebrafish variant had fewer, smaller, and less heavily pigmented
    melanosomes than normal fish.

    The mutation

    Keith Cheng of Penn State College of Medicine and his colleagues determined 
that
    a dysfunctional, mutated gene was not producing the protein needed to make
    melanosomes.

    "They have a mutation in the gene which causes the protein machinery to say
    `stop,'" Cheng told LiveScience.

    Cheng's team found that when they inserted the normal version of the gene 
into
    two-day-old embryos of the golden fish, they were able to produce 
melanosomes,
    which darkened their skin to the normal color within a few days.

    Next, the researchers searched HapMap, an online database of human genetic
    variation, and found a similar gene for melanosome production in humans. So 
they
    inserted the human gene into golden zebrafish embryos and again changed 
their
    skin color to the darker version.

    "We presume that they got darker because of similar function of the inserted
    gene which normally produces the more abundant, larger, and darker 
melanosomes,"
    Cheng said.

    Human mutation?

    It appears that like the golden zebrafish, light-skinned Europeans also have 
a
    mutation in the gene for melanosome production, resulting in less pigmented
    skin. Scientists suspect variations of this gene may also cause blue eyes 
and
    light hair color in some humans.

    However, Cheng said, it's important to point out that the mutation in the 
human
    and zebrafish genes is different--while the zebrafish version fails 
completely
    to produce the protein to make melanosomes, the mutated human version still
    works, just not quite as well.

    The discovery could lead to advancements in targeting a treatment for 
malignant
    melanoma--the most deadly form of skin cancer--as well as research on ways 
to
    modify skin color without damaging it by tanning or the use of harsh 
chemical
    lighteners.

    This research is detailed in the Dec. 16 issue of the journal Science.

      * [35]Pollution Blamed for Intersex Fish
      * [36]The Real Reason Animals Flaunt Size and Color
      * [37]Bragging Rights: The Smallest Fish Ever
      * [38]Fluorescent Fish Aids Medical Research

    [39][051215_zebrafish_00.jpg]
    [40]The normal zebrafish above has darker stripes than the golden zebrafish
    below. The insets show that the golden zebrafish has fewer, smaller and less
    dense pigment-filled compartments called melanosomes than the normal 
zebrafish.

References

   34. 
http://www.livescience.com/php/multimedia/imagedisplay/img_display.php?pic=051215_zebrafish_02.jpg&cap=The+normal+zebrafish+above+has+darker+stripes+than+the+%ECgolden%EE+zebrafish+below.+The+insets+show+that+the+%ECgolden%EE+zebrafish+has+fewer,+smaller+and+less+dense+pigment-filled+compartments+called+melanosomes+than+the+normal+zebrafish.+Credit%3A+%A9+Science
   35. http://www.livescience.com/environment/intersex_fish_041221.html
   36. http://www.livescience.com/animalworld/ap_050319_deer_antlers.html
   37. http://www.livescience.com/animalworld/041027_Smallest_Fish.html
   38. http://www.livescience.com/imageoftheday/siod_050901.html
   39. 
http://www.livescience.com/php/multimedia/imagedisplay/img_display.php?pic=051215_zebrafish_02.jpg&cap=The+normal+zebrafish+above+has+darker+stripes+than+the+%93golden%94+zebrafish+below.+The+insets+show+that+the+%93golden%94+zebrafish+has+fewer%2C+smaller+and+less+dense+pigment-filled+compartments+called+melanosomes+than+the+normal+zebrafish.+Credit%3A+%A9+Science
   40. 
http://www.livescience.com/php/multimedia/imagedisplay/img_display.php?pic=051215_zebrafish_02.jpg&cap=The+normal+zebrafish+above+has+darker+stripes+than+the+%93golden%94+zebrafish+below.+The+insets+show+that+the+%93golden%94+zebrafish+has+fewer%2C+smaller+and+less+dense+pigment-filled+compartments+called+melanosomes+than+the+normal+zebrafish.+Credit%3A+%A9+Science