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  1. #1
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    Default Why do clones have different markings?

    I was just looking at pictures of Sapphire and her two 3 year old clones and each has a different blaze. Anyone know why? I thought a clone would be a duplicate.



  2. #2
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    Markings are part genetic, part environmental.....

    Jennifer



  3. #3
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    Because although they have identical genes, those genes can be expressed differently. To greatly simplify this idea - two horses may have the same color genes for a chestnut coat, but they will be different shades of red. The clones all have the same genes which determine that they will have a blaze, but the exact shape and size can differ. And yes, for markings there can be some environmental factors as well (in utero).



  4. #4
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    No idea if it's "exact" or not, but I was always told that the general marking was genetic, the end product a factor of liquid swirling in the womb as the cells were forming.
    If A equals success, then the formula is: A = X + Y + Z, X is work. Y is play. Z is keep your mouth shut. - Albert Einstein



  5. #5
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    Epigenetic markers....the same reason my identical twin sons don't look exactly alike:

    http://www.sciencenewsforkids.org/20...en-from-birth/



  6. #6
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    It's not the same as the shade of color - those genetics are pure genetics (though diet/environment could make them look a bit different at times due to sun exposure or not, sufficient nutrition or not, etc). Liver is liver, that comes from inside.

    But the uterine environment is thought strongly to play some role in the shape and general size of white markings. But the clones are still going to have a blaze, of sorts, if the original did, still going to have white legs if the original did. But the size and placement can vary a bit.

    Top Gun had 3 white legs - his clone, Cryozootech Top Gun, has 4

    But an original with a little star and nothing else isn't going to sprout a clone who has white legs and a big ol' belly splotch
    ______________________________
    The CoTH CYA - please consult w/your veterinarian under any and all circumstances. - ET


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  7. #7
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    I don't think anyone knows what actually leads to the position and extent of white markings on horses. I've read that it has to do with the migration..or lack thereof...of melanocytes (the pigmented skin cells) to the distal part of the limb bud during early development. If they don't make it all the way out there and proliferate, parts of teh body are unpigmented (white). The same probably directs melanocyte migration to the in the head. White patches = lack of melanocytes. Errors in directions to these cells cause white spots. As people who bred horses liked white patches, these coat patterns stayed in the gene pool. They're definitely inherited.

    The answer, though, is differences in gene expression in a cell. Clones have identical DNA, but the way the DNA is transcribed to RNA, and the way the RNA is translated to making a protein, can be specific to the cell. There are epigenetic factors - basically, chemicals that adhere to certain parts of the genome - that dictate NOT whether the DNA is there, but how often the DNA is read to make RNA and how efficiently that is made into functional proteins. Think about a fertilized egg. It divides into two cells, then 4 cells, then 8 cells, then 16 cells, then 32 cells, etc. Every time the cell divides, it has to make a perfect copy of its DNA. The cell machinery isn't always perfect and little changes in DNA can occur. Also, those chemicals that can affect gene expression can get added or subtracted as cells divide. Many of them, however, are passed on to the daughter cells. That's how identical cells can have different levels of gene expression, and how people and horses and dogs with identical DNA can express that DNA differently and have unique physical features.

    People used to say that differences in mare markings are due to the mare's womb, becuase two identical twins can have different markings. But twins from the same horse can have different markings and I think our understanding of genetics and epigenetics has evolved greatly since those first articles were published in the 80s and 1990.
    Proud member of the Colbert Dressage Nation


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  8. #8
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    Default

    Thanks guys, very informative!



  9. #9
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    Did a story on this and was told by a genetics expert that what is inherited is the tendency to have white markings. Where they end up is due to conditions in the womb.
    co-author of
    Duel for the Crown: Affirmed, Alydar, and Racing's Greatest Rivalry
    www.duelforthecrown.com


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  10. #10
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    Can someone post a link to a pic? I'd love to see!
    Destiny is not a matter of chance, it is a matter of choice; it is not a thing to be waited for, it is a thing to be achieved. - William Jennings Bryan

    http://www.halcyon-hill.com



  11. #11
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    Here's the best picture I know. Smart Little Lena top, and his 5 clones as foals
    http://justthinking.us/sites/default...a%20Clones.jpg

    Here they are as youngsters
    http://4.bp.blogspot.com/-yeb_22Wllw...a%2Bclones.jpg
    ______________________________
    The CoTH CYA - please consult w/your veterinarian under any and all circumstances. - ET


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  12. #12
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    Quote Originally Posted by JB View Post
    Here's the best picture I know. Smart Little Lena top, and his 5 clones as foals
    http://justthinking.us/sites/default...a%20Clones.jpg

    Here they are as youngsters
    http://4.bp.blogspot.com/-yeb_22Wllw...a%2Bclones.jpg
    How interesting!! They DO all have the same ears, though...
    "Hope is a good thing, maybe the best of things, and no good thing ever dies."

    "It's supposed to be hard...the hard is what makes it great!" (Jimmy Dugan, "A League of Their Own")


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  13. #13
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    Another great article about this phenomenon:

    http://theamericanscholar.org/my-for...medium=twitter

    As mentioned above, I have identical, er well, monozygotic, twin sons, so this has been a topic of special interest for me.

    Enjoy!



  14. #14
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    Quote Originally Posted by Dr. Doolittle View Post
    How interesting!! They DO all have the same ears, though...
    That's the 1st thing I noticed too, there ears were identical!! And their head shape too looked similar even without the same markings.



  15. #15
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    Those things SHOULD be (nearly) identical
    ______________________________
    The CoTH CYA - please consult w/your veterinarian under any and all circumstances. - ET



  16. #16
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    Quote Originally Posted by SportArab View Post
    Did a story on this and was told by a genetics expert that what is inherited is the tendency to have white markings. Where they end up is due to conditions in the womb.
    That's based on an old study. We know so much more about genetics, epigenetics, and cell biology than the late 80's. Who was your genetics expert?
    Proud member of the Colbert Dressage Nation



  17. #17
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    Quote Originally Posted by J-Lu View Post
    That's based on an old study. We know so much more about genetics, epigenetics, and cell biology than the late 80's. Who was your genetics expert?
    Actually, this would have been in the late 90s early 2000s. Unfortunately, don't have access to the story anymore due to several computer meltdowns.
    co-author of
    Duel for the Crown: Affirmed, Alydar, and Racing's Greatest Rivalry
    www.duelforthecrown.com



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