Red Birds Carry On Colorful Chemistry
让鸟儿呈红色的物质

Many red-colored birds have to convert yellow pigments in their food into the red pigments that make their feathers and beaks so brilliant
许多红色的鸟可以将食物中的黄色素转化为红色素，从而让它们的羽毛和喙变得鲜艳。

播音/撰文： Karen Hopkin

翻译：bing

审校：吴非

The redder, the better. And I’m not talking about beets, roses or presidential candidates. I’m talking birds. Well, some birds. In various species, red coloration in a male’s feathers or beak is an indication of fitness. A splash of red can attract a mate or warn off a rival.
越红越好。我不是指甜菜，玫瑰或者总统候选人，我在谈论的是鸟。在一些种类的鸟中，雄鸟的羽毛或喙成红色则代表着它们十分健康。红色的斑点可以吸引异性（配偶）或者向竞争者发出警告。

Now two teams of researchers have determined the chemistry that allows our flamboyantly feathered friends to cloak themselves in crimson. Bottom line: many birds eat plants that are rich in compounds with a distinctive yellow pigmentation—which some birds can modify chemically to form the red pigment that becomes their calling card.
是什么样的化学物质可以让鸟儿们把自己笼罩在红色的大衣下？最近，两组研究人员为我们揭晓了答案：许多鸟类进食的植物富含黄色素，而它们可以把这种物质转化为他们的名片——红色素。

To tease out the details, the scientists compared birds that can make the red compounds with those that can't.
为得到答案，科学家将可以制造红色素的鸟与其他鸟进行对比研究。

The first team studied the red canary, which was created about a century ago by breeders who crossed the more familiar yellow canary with a bird called a red siskin. The researchers combed through the genomes of all three kinds of birds to see whether red canaries got any reddening genes from the siskin side—genes that their yellow brethren lack.
第一个团队研究红金丝雀。大约在一个世纪前，一位饲养员将我们熟知的黄金丝雀与黑头红金翅雀（red siskin）杂交，得到红金丝雀。研究人员梳理了三种鸟的基因，他们想知道红金丝雀是否遗传了黑头红金翅雀拥有，而黄金丝雀缺乏的增红基因（reddening genes）。

Their search pointed them to a member of the cytochrome P450 family. These are enzymes that are often involved in breaking down toxins. The particular enzyme for turning yellow to red was at levels a thousand times higher in the skin of red canaries compared to their yellow fellows. [Ricardo J. Lopes et al., Genetic Basis for Red Coloration in Birds]
结果表明，颜色转变的关键是一种位于细胞色素P450家族（cytochrome P450 family）的酶。该家族的酶常被用于分解毒素。而其中专门用于将黄色素转变为红色素的酶，在红金丝雀皮肤中的含量比黄金丝雀高出一千倍。

The second research team arrived at a similar conclusion based on studies of zebra finches. Most zebra finches have a bright orange-to-red beak. But one kind of mutant zebra finch has a yellow beak.
第二个研究团队对斑胸草雀（zebra finches）进行研究，也得出类似的结论。大多数斑胸草雀的喙呈鲜艳的橘色到红色，但有一种突变的斑胸草雀的喙却是黄色的。

Turns out that these yellow-beaked birds have multiple mutations in and around their P450 genes. Which pretty much cut the yellow-to-red enzyme levels in their beaks down to zero. The findings can be read in the journal Current Biology. [Nicholas I. Mundy et al., Red Carotenoid Coloration in the Zebra Finch Is Controlled by a Cytochrome P450 Gene Cluster]
这表明这些黄喙斑胸草雀的基因在细胞色素P450及其附近发生了多处突变，从而导致喙中将黄色素转为红色素的酶的含量几乎降至零。该发现也被刊登在了《当代生物学》（Current Biology）杂志上。

Interestingly, many birds that are not red still have cytochrome P450 genes—to make red pigments in the retina that enhance their color vision. If they could somehow activate this enzyme in other parts of their bodies, they might both see well and look even better. Or maybe just redder.
—Karen Hopkin

有趣的是，许多不显红色的鸟类也含有细胞色素P450基因，这是为了在视网膜上增加红色颜料进而增强它们对颜色的感知。如果它们能在身体其他部位激活这种酶，它们的视力或许可以变得更好，或者……也许只是变得更红。
—Karen Hopkin