成黑色素细胞生成过程中信号调节的研究进展

动物体内的黑色素细胞合成了黑色素从而决定其肤色和毛色。全身各处的黑色素细胞有2种来源:①由神经管上皮细胞分化而来的视网膜色素上皮细胞;②由神经嵴细胞在胚胎发育早期分化为成黑色素细胞进而发育成熟为黑色素细胞从而行使其功能。通过对小鼠和人类的发育遗传学研究,结果表明神经嵴细胞衍生的黑色素细胞的发育分化是一个非常复杂的过程,受到多重信号因子的调控。其中影响黑色素细胞发育过程的转录因子有SOX10、MITF和PAX3,信号通路有KIT及其配体KITL信号通路、WNT/β-catenin信号通路、EDN3及其受体EDNRB信号通路。MITF被认为是黑色素细胞发育过程中非常关键的调控因子,而3条通路也被认为与神经嵴细胞来源的黑色素细胞的发育有极为密切的关系且能调节MITF功能及其活性。作者总结了这个领域的研究进展并指出早期神经嵴细胞的发育调控可能是乌骨鸡和乌骨绵羊乌质性状形成的根本原因。     

动物黑色素细胞及其相关性状形成机制的研究进展

黑色素细胞是合成黑色素的细胞，由其前体细胞黑色素母细胞分化而来，胚胎期黑色素母细胞的形成有两次，一次是具有黑色素细胞特性的神经嵴细胞沿背外侧迁移而形成，另一次是由沿腹侧迁移的神经嵴细胞亚细胞雪旺氏细胞前体（Schwann cell precursors，SCPs）受到某种信号诱导后形成，这是皮肤中黑色素细胞形成的主要方式。黑色素细胞的形成与动物毛发颜色及其他重要经济性状密切相关，其形成的增多或减少，异位形成或异位侵袭均可能导致相应的疾病，但脊椎动物中具有典型黑色素细胞异位形成特征的乌骨鸡却繁衍至今，而且是重要的食用和药用经济动物。探索黑色素细胞的形成及其对相关性状的影响不但能为动物经济性状育种提供相关理论基础，也可为相关疾病的治疗提供理论依据。作者从黑色素细胞的来源及其形成过程中参与的信号因子来探讨其形成机制，并对黑色素细胞相关性状的形成机制尤其是乌质性状进行综述。     

Proportions of melanocyte stimulating hormone-immunoreactive cells in the adenohypophysis of Silky fowl and hyperpigmentation-free cockerels

Alpha‐melanocyte stimulating hormone (α‐MSH) is one of the main regulators for melanocytes, and the adenohypophysis is one of the major tissues for the synthesis of this hormone. The Silky fowl is a characteristic breed of chicken with hyperpigmentation throughout the body. The involvement of the adenohypophysis in the hyperpigmentation of this breed is not known. In the present study, the proportion of melanocyte stimulating hormone‐immunopositive cells (MSH cells) in the adenohypophysis was immunocytochemically compared between Silky, Red Cornish × New Hampshire (RN) crossbred and Japanese bantam cockerels at 15 weeks of age. After the body and gland were weighed, the adenohypophyseal cells were enzymatically dispersed and immunostained for α‐MSH, and the immunopositive MSH cells were counted. The weights of the body and adenohypophysis were heaviest in the RN crossbred, followed by the Silky and lightest in the bantam cockerels. In contrast, the ratio between adenohypophysis and bodyweight was much larger in the Silky and the bantam than in the RN crossbreed (P < 0.05). The population of MSH cells in the adenohypophysis was larger in the Silky (14.3%) than in the RN crossbreed (8.0%) and the bantam (8.1%) cockerels (P < 0.05). From these results, it was concluded that prepubertal Silky cockerel have numerous MSH cells in the adenohypophysis suggesting a relationship to hyperpigmentation.     

Pigmentation of the aortic and pulmonary valves in C57BL/6J x Balb/cByJ hybrid mice of different coat colours

Neural crest‐derived melanocytes have been recorded in several parts of the mammalian heart but not in the pulmonary valve. We report here the presence of melanin‐containing cells in the leaflets (cusps) of both the aortic and pulmonary valves. A total of 158 C57BL/6J x Balb/cByJ hybrid mice exhibiting four coat colours, namely black, white, agouti and non‐agouti brown, were examined. We sought for any relationship between the presence of melanocytes in the valves and the coat colour of the animals. The pigmentation levels of the leaflets were accomplished using a scale of five pigment intensities. White mice lacked pigment in the heart. In 10.5% of the remaining animals, there were melanocytes in the pulmonary valve leaflets. Thus, this is the first study to report the presence of such cells in the pulmonary valve of mammals. Melanocytes occurred in the leaflets of the aortic valves of 87.2% of mice. The incidence of melanocytes and the pigmentation level of the leaflets did not statistically differ according to the coat colours of the animals. This disagrees with previous observations, indicating that the amount of melanocytes in the heart reflects that of the skin. The incidence and distribution of melanocytes in aortic and pulmonary valves are consistent with the notion that the formation of the arterial valves is mediated by specific subpopulations of neural crest cells. We hypothesize that melanocytes, even not producing melanin, may be more frequent in the heart than previously thought, exerting presumably an immunological function.     

急性热应激对泰和乌骨鸡胸肌酪氨酸酶表达和黑色素含量的影响

试验旨在研究急性热应激对泰和乌骨鸡胸肌酪氨酸酶基因表达及黑色素含量的影响。选取144只42日龄泰和鸟骨鸡．随机分为2组：即常温对照组和急性热应激组,每组4个重复．每个重复18只鸡。结果表明,急性热应激极显著地提高了热应激12h时泰和乌骨鸡胸肌酪氨酸酶mRNA的表达（P〈0．01）,并具有提高其热应激24h时的表达量的趋势（P〉0．05）,对其恢复常温后24h、6d、20d的表达量无显著影响（P〉0．05）;急性热应激极显著地降低了热应激24h时泰和乌骨鸡胸肌黑色素的含量（P〈0．01）。并具有降低其热应激12h时黑色素含量的趋势（P〉0．05）,极显著地提高了其恢复常温后24h时胸肌黑色素的含量（P〈0．01）,对其恢复常温后6d、20d的黑色素含量无显著影响（P〉0．05）。     

云南地区乌骨绵羊黑色素的初步研究

对7只兰坪乌骨绵羊、4只本地绵羊(非乌骨绵羊)和2羽乌骨鸡组织器官黑色素进行了测定,结果表明:乌骨绵羊黑色素与乌骨鸡黑色素的IR光谱基本一致,黑色物质主要是真黑色素;乌骨绵羊各组织器官中的黑色素含量高于本地绵羊;黑色素在乌骨绵羊组织器官中的沉积表现出明显的时(年龄)空(组织器官)差异,即随着年龄的增加,组织器官中的黑色素含量也随之增加;各组织器官中黑色素含量高低顺序为肝脏>气管、心脏、肾脏>脾脏、肺>舌、肌肉、皮肤>骨骼,与乌骨鸡的沉积模式有所不同;乌骨绵羊组织器官中黑色素含量与绵羊的毛色有关,黑毛绵羊组织器官黑色素含量高于花毛绵羊。     

Age-related changes in the intramuscular distribution of melanocytes in the Silky fowl

1. The characteristics of melanocyte distribution in skeletal muscles in the Silky fowl were investigated in association with growth. 2. Pectoralis (PT) and iliotibialis lateralis (ITL) muscles from 1-, 3-, 5-, 10-, 20- and 30-week-old Silky males were weighed and collagen type I was detected in frozen sections immunohistochemically. 3. Melanocytes were observed in the collagen type I-immunopositive endomysium and perimysium in both muscles. 4. Image analysis indicated that the total area occupied by melanocytes in histological sections sharply decreased from 0.61% to 0.16% in PT muscle and from 1.67% to 0.33% in ITL muscle at 1 to 3 weeks, and then gradually decreased. The melanocyte area was larger in ITL muscle than in PT muscle until 10 weeks of age. 5. We concluded that the proportion of intramuscular melanocytes in the Silky fowl differs between types of muscles in the early stages of development, and it decreases with growth.     

家鸡羽色性状遗传调控机制研究进展

自然界中鸟类呈现出丰富的羽毛颜色,羽色性状在躲避天敌、捕食、求偶及抵御紫外线等方面都具有重要作用。对鸡羽毛颜色性状的研究有助于加强品种区分、识别,在育种工作中建立品种间的显著标识和保障同一品种外观整齐尤为重要。羽毛颜色是禽类表型遗传研究的重要组成部分,它主要由黑色素和类胡萝卜素所决定。目前鸡羽毛颜色性状遗传调控机制的研究大多集中在黑色素相关通路,其中,Wnt、KIT/KITL和EDN3/EDNRB等信号通路对黑素细胞的生长发育、迁移和分化具有重要的调控作用,α-MSH/ASIP-MC1R信号通路负责调控黑色素的合成。已有研究显示,通过全基因组范围内的遗传变异检测技术挖掘与羽色性状相关的基因和变异位点,可以揭示黑羽、麻羽、显性白羽、隐形白羽、常染色体白化、银羽、性连锁不完全白化、深棕色羽、淡紫色羽(灰羽)、非依赖酪氨酸酶的隐性白羽、斑点羽和性连锁横斑羽(芦花羽)等多种羽色性状的遗传调控机制。此外,以图灵模型为理论基础可以解释复杂羽色图案的形成机制。作者通过总结黑色素相关调控通路与图灵模型对家鸡羽毛颜色性状的遗传调控机制,对近年来已经确定基因座的家鸡羽毛颜色性状相关研究展开综述,以期为鸡羽色分子机制研究以及在育种过程中开展鸡羽色性状标记辅助选择提供参考。     

中国地方品种丝羽乌骨鸡白细胞介素2基因的克隆及遗传进化分析

鸡白细胞介素2（ChIL-2)是近年来新发现的一类细胞因子。根据Sundick等发表的鸡IL-2基因序列设计一对特异性引物,从ConA体外激活的脾脏淋巴细胞中提取mRNA,通过RT-PCR方法扩增和克隆了我国地方品种丝羽乌骨鸡IL-2cDNA,丝羽乌骨鸡IL-2基因由734nt组成,编码-由143个氨基酸组成的前体蛋白,基因5’端含有17个核苷酸和3'端含有285个核苷酸组成的非编码区,3'UTR中含有4个重复的“ATTTA”序列。编码蛋白氨基酸与Kestrel,Obese和SC品系的来杭鸡比较,氨基酸的突变主要发生在28-32位,这一区域丝羽乌骨鸡和Kestrel来杭鸡相同,Obese和SC鸡相同,基因系统进化树分析表明丝羽乌骨鸡和Kestrel来杭鸡具有很近的亲缘关系,Lbese和SC鸡具有很近的亲缘关系。中国的药用鸡品种-丝羽乌骨鸡在非常保守的133位发生了氨基酸突变,我们推测这可能与该品种鸡具有很强的抗病能力有关。     

Five alternative splicing variants of the TYR gene and their different roles in melanogenesis in the Muchuan black-boned chicken

1. The TYR gene encodes tyrosinase, a multifunctional enzyme that is essential for melanin biosynthesis in melanocytes. This experiment involved the cloning and characterisation of the TYR gene in chicken. Five alternative splice variants were identi?ed in the black feather bulb and designated as TYR-AS1, TYR-AS2, TYR-AS3, TYR-AS4 and TYR-AS5.

2. Among the 11 chicken tissues examined, the feather bulb, comb and skin showed higher levels of all TYR variants. All TYR variants were expressed at significantly different levels in black and white feather bulbs (P < 0.05) and may be involved in melanin formation in plumage. Only TYR-AS1, which plays an important role in muscle melanogenesis, was significantly differentially expressed between black and white muscle (P < 0.01). All TYR variants were expressed at significantly different levels in black and white skin (P < 0.01).

3. The mRNA expression levels of the 5 variants were closely associated with skin melanogenesis in the chicken. These findings provide new clues to the molecular mechanism of melanin formation in the Muchuan black-boned chicken.     

The biology of melanocytes

In veterinary medicine, our understanding of the biology and regulation of melanocytic function is mostly based on information realized from human and murine studies. Improved understanding of the biology of melanocytes is needed to develop more effective treatment regimens for malignant melanoma and other melanocytic disorders. In vertebrates, melanocytes are well known for their role in skin pigmentation, hair and feather coloration, and for their ability to produce and distribute melanin to surrounding keratinocytes. Enzymes involved in melanin synthesis are present exclusively in melanosomes. The type of melanin synthesized by melanocytes in mammals is regulated at a genetic, biochemical and environmental level. These regulatory factors affect not only the phenotypic appearance, but also the photoprotective properties of melanin. This review addresses the biology of melanocytes, melanin synthesis and the photoprotective properties of melanin.     

Nutritive constituents of Silky fowl eggs: comparison with hen eggs of White Leghorn origin

In the present study, proportional parts, amounts of major constituents, vitamins, minerals and fatty acids composition of Silky fowl eggs were examined compared with those of hen eggs. The ratio of egg yolk weight to whole egg weight of Silky fowl egg was significantly larger than that of egg yolk of hen egg. The amount of cholesterol of Silky fowl eggs were significantly (P < 0.01) less than those of hen eggs. The amount of vitamins (B2, B6, D and E), calcium and potassium in Silky fowl eggs were significantly higher than those of hen eggs. Unsaturated fatty acids in Silky fowl eggs were 62.5% among total fatty acids, the unsaturated fatty acids of hen eggs were 53.9%. Especially, the contents of arachidonic acid, docosapentaenoic acid and docosahexaenoic acid in Silky fowl eggs were significantly larger than in hen eggs.     

脊椎动物神经嵴细胞发育相关非编码RNA研究进展

神经嵴是脊椎动物胚胎发育中的一种过渡性结构,神经嵴细胞经诱导后可迁移、分化成机体多种类型的细胞以形成重要组织的一部分。研究显示,部分非编码RNA对神经嵴细胞发育具有一定调控作用。非编码RNA是一种不参与编码蛋白质,对转录后水平的基因表达有调控作用的RNA。神经嵴细胞的正常发育影响着机体重要组织的发育,相关研究对于色素异常、肠道神经节细胞发育异常等遗传性疾病的治疗具有重要意义。本文综述了近几年与神经嵴细胞发育相关的非编码RNA研究进展。     

鸡Wnt3a基因组织表达差异与SNPs对鸡毛囊密度性状的遗传效应

Wnt家族成员3a （Wnt family member 3a,Wnt3a）基因是Wnt信号通路的重要成员,Wnt信号通路在动物皮肤毛囊的发生发育中具有重要作用。试验以Wnt3a为候选基因,旨在探讨鸡Wnt3a基因的组织表达差异与单核苷酸多态性（single nucleotide polymorphisms,SNPs）位点对鸡皮肤毛囊密度性状的遗传效应。用实时荧光定量PCR检测Wnt3a基因在鸡不同组织中的表达差异;用PCR扩增直接测序法对Wnt3a基因的SNPs位点进行筛查,验证和分析不同SNPs位点基因型背部毛囊密度的差异;用实时荧光定量PCR技术检测不同品种鸡皮肤组织中Wnt3a基因mRNA表达差异。结果表明,Wnt3a mRNA在皮肤组织中表达量最高,显著高于其他组织（P<0.05）,其次是肝脏、睾丸、卵巢和下丘脑,心脏、胸肌、垂体和脾脏等组织表达量较低。在Wnt3a基因第2和3外显子区各筛选到1个SNP位点：g.2587569 G>A和g.2555812 T>C;在第3内含子区筛选到1个SNP位点：g.2555377 T>C。卡方检验结果显示,3个位点均极显著偏离Hardy-Weinberg平衡。群体遗传参数分析发现,g.2555812 T>C位点为中度多态,有效等位基因数为1.7,遗传变异程度较g.2587569 G>A和g.2555377 T>C位点高。SNP位点分型与毛囊密度的关联分析结果表明,g.2555377 T>C位点CC基因型个体的毛囊密度显著高于TT和CT基因型个体（P<0.05）。在毛囊密度具有显著差异的不同品种鸡的背部皮肤组织中,Wnt3a mRNA表达差异显著（P<0.05）。该研究结果为进一步深入解析Wnt3a在鸡皮肤毛囊生长发育中的作用、筛选与毛囊密度性状相关的辅助育种标记提供了基础资料。     

商品代白羽乌骨鸡早期肉用性能的观测

对商品代白羽乌骨鸡早期肉用性能进行了观测，并以泰和鸡、黄羽乌骨鸡为对照组。结果表明：１０周龄体重，白羽乌骨鸡为１０３１．５ｇ、黄羽乌骨鸡为８５４．６ｇ、泰和鸡为５０３．０ｇ，三个鸡种间差异极显著。三个鸡种饲料转化比、屠宰率差异不显著。     

黑色素细胞相关调控因子研究进展

黑色素细胞是皮肤组织中的一种特殊细胞,黑色素细胞能够产生黑色素并且传递给周围的角质细胞。黑色素传递并停留在这些角质细胞中,能够防止光线辐射对染色体产生损伤,对细胞产生一定的保护作用。黑色素的合成受到许多复杂的调控因子的调控,小眼畸形转录因子在调控黑色素的合成及黑色素细胞的迁移和生存起着非常重要的作用。在小鼠中,干细胞因子或者是它的感受器c-Kit的突变会导致黑色素细胞异常表型。黑色素细胞通过福斯匹林和α黑色素细胞刺激素与黑素皮质素受体结合刺激黑色素的生成;刺鼠信号蛋白会抑制酪氨酸蛋白酶的活性,进而减少黑色素的产量。WNT信号对于神经嵴细胞分化为黑色素细胞有影响,影响黑色素细胞的数量进而影响黑色素的产量。促肝细胞生长素是酪氨酸激酶的感受器,能够促进和保持黑色素细胞产生黑色素的活性。控制合成内皮缩血管肽的受体及配体EDN3的基因的突变会导致黑色素细胞的缺失。     

应用微卫星标记对12个中国地方乌骨鸡品种遗传多样性的研究

利用27个微卫星DNA标记对12个地方乌骨鸡品种进行遗传多样性分析，通过计算等位基因频率、多态信息含量、杂合度、有效等位基因数和遗传距离，评估各品种内遗传变异和各品种间遗传相关，并根据遗传距离对12个鸡品种进行了聚类分析。结果表明，各乌骨鸡群体的遗传多样性较为丰富，并具有较高的选择潜力。平均杂合度最高的是竹乡鸡，为0．670；最低的是江山乌骨鸡，为0．581。27个微卫星标记中4个为中度多态座位，1个低度多态座位，22个为高度多态座位；LEI0234与LEI0192分别检测到了10．3与12．2个等位基因。以标准遗传距离为准，遗传距离最近的为沐川乌骨鸡与略阳鸡，为0．1002，而乌蒙乌骨鸡与略阳鸡最远，为0．2546。通过UPG—MA法聚类后，略阳鸡、沐川乌骨鸡、兴文乌骨鸡、盐津乌骨鸡、竹乡鸡首先聚为1类，江山乌骨鸡、郧阳白羽乌鸡、余干乌骨鸡聚为1类；金湖乌凤鸡、丝绒乌骨鸡和丝毛乌骨鸡聚为第3类；乌蒙乌骨鸡独为一类。     

Distribution of N-acetylneuraminic acid and sialylglycan in eggs of the Silky fowl

1. The distribution of sialic acid in the eggs of original Silky fowl was investigated. The sialic acid contents of the yolk, albumen and the chalaza of a single egg were 205.2, 11.96 and 0.83 mg, respectively. 2. The sialic acid content of the yolk of Silky eggs was 11.5-fold higher than that of a conventional domestic fowl yolk. 3. Sialic acid isolated from Silky yolk was entirely N-acetylneuraminic acid (NeuAc). No N-glycolylneuraminic acid or O-acetyl containing sialic acid was observed. 4. The structure of the major sialylglycan in Silky egg yolk was determined to be a disialyl-biantennary chain in which the NeuAc residues were alpha2-6 linked to glucose. No alpha2-3 linkage was observed. 5. Thus, the Silky fowl's egg provides an excellent source of NeuAc and sialylglycan.     

鸡冷诱导RNA结合蛋白基因序列分析及组织表达

为研究鸡冷诱导RNA结合蛋白(CIRP)基因的结构特征和组织定量分布情况,根据GenBank中原鸡CIRP基因(NM-001031347)的编码区序列自行设计引物,从健康雏鸡脾脏中扩增青脚麻羽鸡CIRP基因的编码区(CDS)并进行生物信息学分析;设计引物建立实时荧光定量RT-PCR,检测CIRP mRNA在雏鸡各组织器官中的分布及相对表达水平。结果显示,鸡CIRP基因CDS区全长573bp,编码190个氨基酸,其氨基端包含一个RNA结合域,羧基端富含RGG重复序列,推导的多肽链羧基端比鸭、斑胸草雀及哺乳动物要多18个氨基酸;CIRP基因在鸡各被检组织器官中均有表达,相对表达水平由低到高分别为法氏囊、肺脏、胰腺、胸腺、脾脏、睾丸、盲肠扁桃体、心脏、脑、肾脏、哈德氏腺、肝脏。本研究为进一步探讨鸡CIRP基因的遗传进化及其在病原感染中的作用提供了参考。     

丝羽乌骨鸡群体遗传结构的微卫星标记分析

用 9对微卫星引物对 170只丝羽乌骨鸡的基因组DNA进行扩增 ,结果表明 ,9个微卫星标记在该品系中都表现出了丰富的多态性 ,所有扩增结果都能重复。微卫星标记平均每个座位检测到 4 .5 6个等位基因 (3～ 7个 )。 9对微卫星引物平均多态信息含量为 0 .6 0 72 ,标记平均杂合度为 0 .74 2 3。本研究的结果可以为进一步利用微卫星进行丝羽乌骨鸡种质特性等研究提供一定的参考