My research about Kohaku is still going on with as much passionate as those first days. Although I have shifted my interest a bit to “irregular red pigment distribution,” the mystery of Kohaku coloration is still an attractive question mark. A few months ago, when looking back those clip and pictures of green Marble swordtail offspring that I used to breed sourcing from Mr. Nekoba, a sudden question came up in me that urged me to Mr. Trochu inquiring about the origin of his Marble swordtails (You will find Marble swordtail very fascinating in the below pictures). After being explained the way Marble swordtails created, I spent extra time gazing at his fish pictures, then realized something in common between the two lines; Something is much of consistency, rather than just a common name “Marble”. So, I pasted all pictures on the same page and start sketching my thoughts, which you could see briefly below in this post. Marble, came from the cross of Hamburg swordtail to Red swordtail represent the interference of black pigment and red pigment, which is dominant in each strain. So, when they are expressed on a single body, they (black and red) started to overlap consecutively, or more accurate, they competed to each other showing distinguishable area of strong expression; or in other words, their competition revealed the areas of origin. On those pictures to the left of Marble swordtails, I drew some black arrows pointing the place where black pigment really invaded and dominant over the red, besides the black lateral pigmentation line along the fish body. Those area would also mean where the red pigmentation be weakest; as the matter of fact, black pigmented area isolated and bring up the areas of red origin. Recalling about my analysis 2 years ago, when I hypothesized that the red coloration is controlled by some genes of a family: 1) Red cap [Hr] gene: express from top head, extend to mouth, gill, neck, chest, then pectoral fins. 2) Dorsal red [Dr] gene: express from high back, around body down to belly, up to dorsal fin if being strong enough. 3) Red tail [Tr] gene: express from caudal peduncle covering lower body till anal fin, also may extend to caudal fin if being strong enough. Now, it seems to me the Marble pattern did support my hypothesis: “Following that suggestion, popular Kohaku Koi phenotype [Red-White-Red] is assumed to be the loss of function in Dr gene [Dr-]. As the matter of fact, when being under strong expression, Hr or Tr gene may cover part of Dr expression region, even overlapping each other, but a suppressed Dr [Dr-] always show a triangle of white pattern as shown in the second picture below. Source:https://ctswordtail.weebly.com/blog/kohaku-koi-swordtail-coloration-hypothesis-based-on-phenotype-observation#comments” From the angle of research by observation-based data, my hypothesis would be very limited support, but I hope in the future I could hand on genetics research technique to decode the mystery of Kohaku swordtail. (to be continued…)
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AuthorDay by day, night by night, my hobby keeps surviving in limited time and space, but never stop! Categories
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September 2019
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