An Tana, Dugarjaviin Manglai, Han Haige
Inner Mongolia Key Laboratory of Equine Science Research and Technology Innovation, Inner Mongolia Agricultural University, Hohhot 010018, China.
Genes (Basel). 2024 Dec 11;15(12):1589. doi: 10.3390/genes15121589.
BACKGROUND/OBJECTIVES: The Mongolian horse, one of the oldest and most genetically diverse breeds, exhibits a wide variety of coat colors and patterns, including both wild-type and unique features. A notable characteristic of dun Mongolian horses is the presence of Bider markings-symmetrical, black-mottled patterns observed on the shoulder blades. These markings are also seen in Przewalski's horses. The dun coat color, a common wild-type phenotype in domestic horses, is characterized by pigment dilution with distinct dark areas and is regulated by mutations in the gene. This study aimed to investigate the role of in the development of Bider markings in dun Mongolian horses.
Skin tissue samples were collected from three key anatomical regions of dun Mongolian horses with Bider markings: the croup, dorsal midline, and shoulder. Histological staining was conducted to examine the skin and hair follicle structure and pigment distribution. RT-qPCR was used to measure mRNA expression, while immunoblotting and immunohistochemistry were employed to analyze TBX3 protein levels and localization.
Hematoxylin and eosin staining revealed the skin and hair follicle structures, including the epidermis, hair shaft, and hair bulb across different stages of the hair growth cycle. Differences in pigmentation were observed across the sampling sites. The croup and the light-colored area of the shoulder showed asymmetrical pigmentation, while the dorsal midline and dark-colored area of the shoulder displayed symmetrical pigmentation. mRNA expression levels were significantly higher in the croup compared to the shoulder and dorsal midline; however, corresponding TBX3 protein expression did not show significant differences. Immunohistochemical analysis localized TBX3 protein predominantly in the hair bulb and epidermis.
This study demonstrates region-specific differences in expression that correlate with pigmentation patterns in dun Mongolian Bider horses. These findings provide valuable insights into the molecular mechanisms underlying Bider markings, offering a deeper understanding of the genetic regulation of coat color and primitive markings in equines.
背景/目的：蒙古马是最古老且基因多样性最高的品种之一，拥有多种毛色和斑纹，包括野生型和独特特征。蒙古马的一个显著特征是存在比德斑纹——在肩胛骨上观察到的对称、黑色斑驳的图案。普氏野马也有这些斑纹。暗褐色毛色是家马中常见的野生型表型，其特征是色素稀释且有明显的深色区域，由该基因的突变调控。本研究旨在探讨该基因在暗褐色蒙古马比德斑纹形成中的作用。
从有比德斑纹的暗褐色蒙古马的三个关键解剖区域采集皮肤组织样本：臀部、背部中线和肩部。进行组织学染色以检查皮肤和毛囊结构以及色素分布。采用RT-qPCR测量该基因的mRNA表达，同时利用免疫印迹和免疫组织化学分析TBX3蛋白水平和定位。
苏木精-伊红染色揭示了皮肤和毛囊结构，包括毛发生长周期不同阶段的表皮、毛干和毛球。在采样部位观察到色素沉着差异。臀部和肩部浅色区域显示不对称色素沉着，而背部中线和肩部深色区域显示对称色素沉着。该基因的mRNA表达水平在臀部显著高于肩部和背部中线；然而，相应的TBX3蛋白表达没有显著差异。免疫组织化学分析将TBX3蛋白主要定位在毛球和表皮。
本研究证明了该基因表达的区域特异性差异与暗褐色蒙古马比德斑纹的色素沉着模式相关。这些发现为比德斑纹的分子机制提供了有价值的见解，有助于更深入地了解马的毛色和原始斑纹的遗传调控。
