Coat colours in Border Collies边境的被毛色(转)

天边的岸-POCO宠

Biological background of coat colours
被毛色的生物学背景
A certain cell type is responsible for the colour of the skin and coat: the melanocyte. Inside these melanocytes the formation of pigment granules takes place. These granules consist of the actual pigments: eumelanin and phaeomelanin. Eumelanin is responsible for the darker colours such as black, blue, chocolate brown and phaeomelanin causes the lighter yellow/red colours such as tan, red, yellow.
melanocyte（黑色素细胞）是决定皮肤和被毛的细胞形式。在黑色素细胞内部有细小的色素颗粒构成。正是这些小颗粒组成了二种色素：真黑素和棕黑素。真黑素决定了深色系，如黑、蓝、巧克力色；棕黑素则影响浅色的红黄系，如茶色、红色、黄色。
The melanocytes originate in the embryo from the so called neural crest. At a certain point in the development of the embryo these cells migrate to various parts of the body where they will cause the colouring to show. Also various sensory cells (e.g. from the eye and ear) originate from this neural crest. A number of genetic defects of the sensory organs is connected to certain colours and patterns, because of problems with this migration.

黑色素细胞产生于胚胎期的一种称之为neural crest（神经末稍）。在胚胎期，这些细胞被送往全身各部位，从而呈现出颜色。而且各种感观细胞，如眼、耳，也是产生于neural crest。一些感观器官的基因缺陷与某些颜色和形式相联系，正是因为其运送过程中出错了。

Inside the melanocyte a number of mechanisms control the formation of pigment. A couple of enzymes catalyse the chemical transformation from tyrosine to the resulting pigment. The rate of activity of the enzymes is controled through receptors in the cell membrane.
在黑色素细胞中，还有一些因素影响着色素的形成。酶通过催化作用把酪氨酸转化为色素，而酶的活化力受到细胞膜的影响。

The genes that determine the coat colour can influence all of the processes mentioned above (plus a few other processes). The method of interaction of the individual genes (loci) will be explained below if possible.
决定被毛颜色的基因受到上述多种因素的影响，也许还有一些因素。下面解释一下单个基因间的交互作用。
Overview of loci

单基因观点

A (Agouti)
This locus controls the distribution of pigment in an individual hair. This gene acts in the hair follicles where the melanocyte can switch between eumelanin and phaeomelanin (dark pigment and tan pigment). The actual switching mechanism is unknown, but is situated in the dermis and for some alleles in the epidermis.
The agouti colour does not occur in the Border Collie as far as I know.

A（Agouti）　它主要集中于个体的毛发的色素集中度。　此基因作用于毛囊中，也就是黑色素细胞内分化为真黑素还是棕黑素的地方。这个分化过程还不了解，但在真皮层和上表皮层存在。就我所知，这种基因颜色不存在于边境犬中。
The sable colour is rather rare and does often not show the classical effect of a dark dorsal area with a lighter abdomen. The hairs have dark ends. Some authors suggest that Ayat dogs have a darker colour than AyAy dogs. In mice however AyAy is supposed to be lethal (prenatal).
黑貂色十分少有，不会现出常有的黑背浅腹。毛发的尾尖是黑色的。一些作用认为Ayat的狗比AyAy的狗颜色更深。而在老鼠研究中，AyAy则被认为是致命的。

The at allele together with white markings produces the tricolour pattern. The transition of tan coloured hairs to dark hairs is very sudden. Tan markings occur in certain areas: above the eyes, on the cheeks, at the shoulder joint, the front and innerside of the elbow and the lower arm, the front and innerside of the knee and lower leg and below the tail. The dog must be homozygote atat to have tanpoint markings.

当at这对等位基因出现时，就能产生三色的形式。棕色转为黑色是十分突然的，当棕色常出现在如下地方：眼四周、脸颊、肩内侧、肘的前端和内侧、肘根、膝的前端和内侧、膝根、尾根，那么这只狗的基因形式肯定为atat。
Many authors also mention the saddle pattern. The dark colouring is concentrated in a saddle-like patch on the back. On the head one can also find black markings. The pattern is not as specific as the tricolour markings.
许多作者也提到saddle 形式。在背部出现鞍状的黑色斑纹，在头部也可以发现黑色斑纹。这类形式并不是三色的特例。

Alleles
等位基因


A fully coloured　　全色
Ay sable　　　　　貂色
asa saddle　　　　鞍形斑
ag Agouti　　　　　环纹

at tricolour or tanpoint　　三色或tanpoint


B (Black/brown)　黑棕色　
This locus encodes the Tyronsinase related protein 1 (Tyrp1), which catalyzes a quite distal step in the synthesis of melanin. The eumelanin granules in bb animals are brown instead of black and shperoid instead of ovoid.


Alleles　　等位基因
B black　　黑色　现性
b brown　　棕色　隐性



D (Diluted)
The D-gene determines the shape of the melanocytes. In dd animals the pigment cells are misshapen, the pigment granules are fewer and larger, and the cells have fewer and thinner dendritic processes. The result is that the colour looks paler, although melanin production is not affected, nor is the microstructure of the pigment granules. Black becomes blue, chocolate brown becomes lilac.

D基因影响着黑色素细胞的外形，在基因为dd的动物中，色素细胞是畸形的。色素颗粒大而少，细胞加工过程中少而薄小，因而结果是颜色看上去淡化，黑色成了蓝色，巧克力成了淡紫色。
Alleles　　　　
D not diluted　　　　不淡化
d diluted　　　　　　　淡化

E (Extension)
The activity of tyrosinase is controlled by a few receptors in the cell membrane of the melanocytes (so called melanocortin peptide receptors); one of which is MC1R. These receptors bind melanocyte-stimulating hormone αMSH and other melanocortin peptides. The extensions gene interacts with the agouti gene through these receptors: Ay dogs have a defect in the synthesis of αMSH, resulting in phaeomelanin becoming visible.

酪氨酸酶的活化是受到一种称之为melanocortin peptide receptors的黑色素细胞膜内的receptors控制，其中一种receptor就是MC1R.这些receptor影响着黑色素内的荷尔蒙激素（促黑激素）以及其它皮质素的形成。 extensions 基因和agouti 基因通过receptor相互影响,基因形式为Ay的狗在促黑激素上有缺陷，结果就是棕黑素主导。
Dominant alleles cause the extension of eumelan。in and recessive alleles the extension of phaeomelanin
强势基因引起真黑素的扩张，隐性基因引起棕黑素的扩张

Alleles
E eumelanin present　　　　现性　真黑素
e eumelanin surpressed　　　隐性　真黑素被抑制

M (Merle)　陨石

This gene has acquired quite a bad name. If this dominant gene is present only once, the base colour changes into an irregular pattern of various grades of dilution. If the dog has two copies of the allele (homozygous), the dilution is much stronger. The often (nearly) white animals can suffer from blindness, deafness and/or be sterile.

这种基因有一种不好名声。如果有一个其强势基因，狗的基本色就会出现不正常、不同程度的淡化。如果有二个（纯合），这种淡化就十分强烈。几乎这类的白色动物都会是耳聋和眼肓或者不育。

This type of dominance is called 'incomplete dominant'. Although a single Merle gene is visible the effect is fully visible in a homozygous animal.

这类强势称之为不完全控制。一个单基因可见，纯合体则更可见。

To the best of my knowledge there are no adverse effects in heterozygous animals which makes the colour safe to use (if no Merle to Merle matings are used). In general there should be no fear of 'carriers' for this gene since the effect is easily visible. In very rare cases a dog can look like a non-Merle, while he is genetically a merle ("Phantom merle"). When such a dog is mated to a merle part (25%) of the pups will be homozygous for merle. In Sable Merles the merle pattern is actually only visible in pups. Later on the effect is nearly invisible. To be on the safe side one should not mate sables to merles.

就我所知，　杂合体是没什么弊处的（不是墨尔配墨尔），是安全的颜色。总之，当其影响可见时，不必害怕携带这类基因的狗。在很少的例子时，一些遗传性的墨尔看不出它是陨石。当这类狗与墨尔相配，其小狗中有百分之二十五就会出现纯合。在Sable的陨石中，其陨石形式只在小时可见，长大后会变化成几乎不可见。因而，应该避免用Sable与墨尔相配。

Alleles
M Merle　　　　　　陨石
m not merle　　　　非陨石


S (Spotted)
Controls the distribution of colour on the body. Various authors are rather unclear when it comes to describing the different patterns.

控制身体颜色的分布。众多作者在介绍各种不同花纹时都不十分清晰。

S is hardly present in the Border Collie and sw is rare. A few authors mention that sp causes a rather irregular pattern. Probably si is the most common in the Border Collie.
Extremely white Borders usually are swsw (except for double merles).

S基因在边境中几乎不出现，SW很为少见。一些作者提出SP能引起不规则的花纹，有可能SI是边境中较为常见的。特别是白色的边境，通常都是swsw基因形式（除开双墨尔的）

It is very likely that a number of modifier genes causes the variation in markings. Since the variation caused by these modifiers is rather extensive the various markings blend into another marking.

非常有可能，正是这些改基因引起花纹的不同形态，这种变化的扩张与其它形式的花纹相混合。

Alleles
S totally pigmented　　　　　　　　全色
si irish spotted/collie marked　　　柯利花纹
sp piebald spotted　　　　　　　　斑点花　
sw extremely white — only ears and base of tail is coloured　非常白色　只是眼睛和尾根有色


T (Ticking)

The white parts of the dog contain freggles. This causes the mottled effect in the Border.

含白色花纹的狗都有freggle，这影响着边境花斑效果。

Accordign to some authors this gene show intermediary inheritance, so TT animals are heavier ticked than Tt animals.

有些作者认为这种基因是遗传的，所以TT基因形式的动物比Tt形式的有更厚重的tick.
Alleles
T Ticked
t no ticking
M (Merle)　陨石

This gene has acquired quite a bad name. If this dominant gene is present only once, the base colour changes into an irregular pattern of various grades of dilution. If the dog has two copies of the allele (homozygous), the dilution is much stronger. The often (nearly) white animals can suffer from blindness, deafness and/or be sterile.

这种基因有一种不好名声。如果有一个其强势基因，狗的基本色就会出现不正常、不同程度的淡化。如果有二个（纯合），这种淡化就十分强烈。几乎这类的白色动物都会是耳聋和眼肓或者不育。

好可怕，只觉得陨石的眼睛很漂亮，像宝石一样，但是我不喜欢那个颜色，感觉脏脏的
还是黑白好啊，还有巧克力色也很漂亮

以上内容为之家论坛边境版的sumpur翻译的，转载在此处供大家学习。在此向sumpur表示感谢！

边边迷

好复杂，，慢慢看！

凯瑞宝贝

都能看得懂~~学习了!