| The quantity and quality of cashmere are associated mainly with the traits of skin follicle. So it is required to understand skin follicle structure, development and its regulative genes for getting goats with good quantity and quality cashmere by selective breeding. In this study, we firstly evaluated the hair follicle structure, morphogenesis and development of the Inner Mongolian Arbas cashmere goats through histological observation of skin section from different fetal stage. Then by using PCR (polymerase chain reaction), Hoxc9 gene was amplified in different goat varieties (Cashmere goat, Angora goat, Boer goat, Sannen and Zang goat). Moreover both their nucleotide and amino acid sequence were also analyzed by the method of bioinformatics. Finally, we cloned fourteen Hox gene fragments of cashmere goat, and investigated the expression of Hox gene during hair follicle development through in situ hybridization. The results suggested as following:1. The original of primary hair follicle could be seen firstly over all goat skin during 55 to 65 day of fetal stage, but its complete structure formed till 105 day, and its development process would finish in 135 day. While the original of secondary hair follicle appeared only in the side of neck in day 65 and spread through whole body in 75 day. Till 105 day, its complete structure came into being. And it got maturation after 125 day.2. The primary and secondary hair follicle grew fastest at the stage of 95～115 day and 105～125 day respectively during whole process. At the same time, their maximal densities were seen separately at the age of 75～85 day or 105～125 day, the value of S/P got highest from 115 day to birth. So in 85 day and 105 day, primary and trio hair follicle group formed respectively.3. The complete structure of epidermis layer was formed at the age of 55～65 day and reached the thickest during 85～95 day, then thickness began to shrink and suddenly enhanced at birth. However, thickness of dermis increased rapidly at the age of 95～125 day and decreased right before birth.4. The Hoxc9 gene of cashmere goat was cloned (GeneBank Accession: DQ873298). Its length of DNA and cDNA was 3308bp and 783bp respectively, which encoded 260 amino acid. Furthermore, the nucleotide and amino acid sequence of Hoxc9 kept high homology in mammalian. Its amino acid sequence had different function sites, and three helixes, three turns and random coil in its tertiary structure. 5. The results of in situ hybridization study showed that mRNA of Hoxc9 gene began to express firstly in epithelial cell in day 75. With development of hair follicle, it expressed in hair matrix, dermal papilla, inner root sheath, outer root sheath and hair shaft. Meanwhile, lots of keratinocytes proliferated during this process. This result indicated that Hoxc9 gene might play a role for proliferation of keratinocyte.6. After Hoxc9 gene of Angora goat, Boer goat, Sannen and Zang goat were amplified by PCR, we found that their nucleotide homology was very high compared with cashmere goat's. And fourteen members of Hox gene family were cloned in cashmere goat, every gene fragment was composed of 117 nucleotides, which encoded a high conservative 39 amino acid peptide. Through in stiu hybridization, the positive signal of HoxA4, HoxA5, HoxA6 and HoxA7 was detected in hair follicle. |
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