 Name: Folio Navigation guide is always with me. Feel free to ask anything about Studio.  イノは比較的良く知られた遺伝子 ですが、ダイリュートは あまり有名ではないかも知れません イノ遺伝子は 黒と濃褐色を消す性質がありますから 原色に掛けてても、茶に掛けても 写真のような色合いになります （注）黒だけを消すのが茶の遺伝子 ダイリュートは 色素の「種類」には影響がなく 色素の「量」だけを減らす性質があります 原色に掛けると薄いチョコレート色に （ブラックブラウンのダイリュート） 茶に掛けると薄い茶になります （フォーンのダイリュート） 薄い茶は一見すると「濃いイノ」の ように見え、目も赤みを帯びるので 遺伝的な意味は全く異なるのですが 現象の類似性から 一般にはイノとして扱われるようです （実際にはダイリュートなのですが） そんな訳で イノとダイリュートを混同した 交配が多かったと考えられ イノと称する個体には ダイリュート遺伝子を持ったものが 多いようです ダイリュートは劣性遺伝子なので 通常は隠れていて 一定の確率で現れます イノを育てていて、色の極端に薄い 子供が出てきたらダイリュートが 入っていたことになります 右図のダイリュート・イノは そのイノとダイリュートが 同時に現れた場合の色合いです  右図でご紹介しなかったのが 白いジュウシマツです 全身真っ白といっても遺伝的には 二種類があります： (a)色素に着目した場合 右図のライン上の究極の姿が 「アルビノ」と呼ばれる白です 色素を作る機能が全くないので 真っ白になります 目も赤く透けて見えます 但し、注意が必要なのは アルビノは白くても柄模様は ちゃんと持っているということです 模様に色がつかなので 判別できませんが 柄の遺伝子はちゃんと持っています (b)この対極が「白ジュウ」です 白ジュウの場合、色素を作る機能は 完全に働いています 目も黒く色素をもっています 但し、柄模様が全身白斑という 模様なしの状態になっています 同じ白でも(a)と(b)は 遺伝的には正反対の状況です 目の色の違いだけじゃ ないのですね |
SECRET OF COLOR :Pigment System of Society Finch Come on and look! This is the introduction of one of the breeding techniques to control colors of Society Finch. The face color of the finch is defined by layers of several pigments and patterns; It is like a pointillism picture; You may recall, for example, a Georges Seurat. Here is how. It is so amazing! ■ 
■TOP■INSIDE THE WARDROBE ■THREE STEPS FOR DILUTION ■TO MAKE A SET OF IDENTICAL GENES 【INSIDE THE WARDROBE】 Today, we have about 180 colors for Society Finch. Scholarly research on this subject has been made by Kanji Kawabata, who is a genetics scientist and is believed to be the best Society Finch expert in the world. An extensive reference is available at his website "Invitation to Bengalese Finch (at p.5-4)". Since it may be too extensive to review them all here, just a part of the basic system for a gradational color change, the Studio's favorite, is introduced (still very long!):  ■
■TOP■INSIDE THE WARDROBE ■THREE STEPS FOR DILUTION ■TO MAKE A SET OF IDENTICAL GENES 【THREE STEPS FOR DILUTION】 The base color of Society Finch is called Black-Brown. It is a very dark brown color made by mixture of several different kinds of melanin; for instance, Black, Dark-Brown and Brown. That means each melanin "dot" has pure color; but collectively "dots" are seen as Black-Brown. Understanding the structure, we remove each kind of melanin, just one by one, to make nicely diluted face colors. Three types of genes help us: ＜STEP 1: Effect of Fawn Gene＞ Fawn Gene is recessive and hinders formation of Black melanin. (Recessive heredity will be explained later.) Since Black melanin dots are removed, it is seen as clear Brown. Black melanin disappears also from beaks and legs, so that those parts become pastel pink. It may be hard to notice, but you can find that eyes of Brown Finch also have been diluted by Fawn Gene to be red wine color in the sunlight. Aren't they sweet? ＜STEP 2: Effect of Ino Gene＞ Ino Gene hinders formation of both Black melanin and Dark-Brown melanin. The gene is recessive and sexlinked. (Sexlinked heredity will be explained later.) Since Black dots and Dark-Brown dots are removed, it is seen as nicely diluted cream color and is called a Cream-Ino. Beaks and legs of Cream -Inos are pastel pink and, most notably, eyes of them are shining red! ＜STEP 3: Effect of Dilute Gene＞ While above mentioned genes hinder some levels of melanin formation, Dilute Gene has an effect on "quantity" of melanin. By importing Dilute Gene into a Cream-Ino, for example, we breed a bird with a more subtle and diluted color. Density of pigments becomes so low that a body of a bird becomes almost white; you only see very light brown "shadows" left. It is often hard to distiguish Diluted Cream-Inos from white ones. ■
■TOP■INSIDE THE WARDROBE ■THREE STEPS FOR DILUTION ■TO MAKE A SET OF IDENTICAL GENES 【TO MAKE A SET OF IDENTICAL GENES】  A phenotype is defined by a pair of genes of chromosomes. One gene is from the father and the other is from the mother. The phenotype seen only when identical genes are met is called "recessive". Both Fawn heredity and Dilute heredity are recessive. ＜1. Recessive Inheritance＞  In a cross of Normal Finch and Dilute Finch, we only have the Normal appearance in the next generation, although the Dilute Gene has been inherited in all cases. We see the Dilute appearance, one out of four, in the third generation. The Ino appearance also requires the pair of identical genes, but is somewhat unique because it is "sexlinked". The Ino Gene happens to be on a sex chromosome, so that expressions differ depending on the genders. Please remenber that the types of sex chromosomes of birds are described as ZZ(male) and ZW(female); while those are XY(male) and XX(female) for human. The Ino Gene is linked with the Z-chromosome; therefore a hen carrying a Z-chromosome with an Ino Gene appears to be cream color. ＜2. Sexlinked Inheritance＞  In a cross of an Ino cock and a Normal hen, all the hens in the next generation become Inos, while all the cocks, each of which carries an Ino Gene with one of its Z-chromosomes, become Normals. We see Ino cocks, one out of two, in the third generation. Although there may be exceptions, it is the herediary rule that to make a set of identical genes of chromosomes is required to fix a certain phenotype. That is always the goal. by Folio, as Navigator by Kaz, Finch Studio 2005.08.08 (1st script) 2006.10.21 (English Edition) |
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