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Thread: Genetically Enginneered Koi

  1. #11
    Daihonmei MikeM's Avatar
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    Well, Ric, you got me reading about piebald patterning. The scientific literature loses me fairly quickly. The 'dumbed down' attempts are not very satisfactory, but there is a good bit written by dog and cat breeders. I've also come across internet essays concerning all sorts of animals from horses to pythons. Piebald patterning does seem to have a randomness to it, but there are also tendencies, such as the white blaze on the head of a horse. It is said that with pythons the head is least likely to have white/yellow to appear. With cats, the tail is said to be least prone to white spotting. There seems to be a common theme that with repeated selective breeding the randomness of the spotting can be reduced and something like a consistent patterning can appear, but my impression is that even with determined effort identical patterning is not reliably accomplished. What is accomplished is a strengthened tendency for the spotting to appear in particular places/areas.... or for the 'spots' to become huge, giving an impression of a white base color with patches of other colors.

    So, the notion of being able to assure a specific pattern in koi seems farfetched today.

    Here is a discussion about cats that is rather typical of the sorts of things I've found written about several types of animals:

    PIEBALD SPOTTING

    White spotted, or piebald, cats are very common.� Spotting may occur with any coat color, and is mainly due to the effect of one gene with two co-dominant alleles. The spotted allele, S, creates responsible for white spots, while the s allele is not.� Hence, the homozygote, ss, has no white spots.� The heterozygote, Ss, has restricted areas of white spotting; usually the feet, nose, chest, and belly.� Finally, the SS homozygote has white regions covering more than half the body.� In the latter case, people usually consider the dark patches to be spots.� However, in reality, it is the larger white area that is the spot, and in fact, a �spotted� (SS) cat may even be completely white!

    The degree of spotting varies tremendously, but spotting patterns usually follow a regular progression.� Cats with the least spotting have small spots on the breast and belly.� Increased spotting seems to progress to cover the entire belly, the neck, chin and front feet.� Finally, cats with the most spotting have spots up the sides, over the back and onto the head.� The tail seems to be the last area to have white spots.� Since cats vary continuously in the extent of spotting, and the pattern of spotting is not completely random, it is unlikely that only one gene determines the degree of spotting.� There is evidence of at least one other gene that has a weak spotting effect.� It can cause a very small white spot on the throat, breast, or on the belly near the hind legs.� In fact, several genes probably modify the action of the major spotting gene to produce the continuum of spotting patterns seen in cat populations.� Since the action of these weak modifier genes is not well understood, we will score only the major spotting gene in our cat survey.

    The spotted allele, S, hampers the migration of melanocytes during embryonic development.� White spots are areas lacking melanocytes.� Thus, within these patches a spotted cat will exhibit the same pleiotropy as caused by the dominant-white gene.� For example, if an eye is within a spot, it will be blue.� Thus, spotted cats may be blue-eyed or odd-eyed.� Further, if the spot encompasses an ear, the cat will be deaf in that ear.� Since a spot often covers the eye when it covers the ear, an odd-eyed cat will frequently be deaf on the blue-eyed side.�

    The spotting gene has in interesting effect on the patterning in tortoiseshell (Oo) cats.� With the ss genotype, there is no white spotting and the orange and black are intermingled, usually without large patches of either orange or black.� With either Ss or SS genotypes, there are white spots and the orange and black occur as distinct patches.� These cats are called calico cats (or, sometimes, tortoiseshell and white).� This pattern seems to be due to the effect of the spotting allele on embryonic melanocyte migration.�

  2. #12
    Honmei ricshaw's Avatar
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    I breed birds. With birds we tell people that the range of Pied expression can go all the way from a bird with only one white feather to an all white bird.

  3. #13
    Daihonmei MikeM's Avatar
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    It's nice to be learning more all the time.

  4. #14
    Tategoi bobbysuzanna's Avatar
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    Will be interesting to see how they get around the tetraploid genome issues that koi possess.

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