Morphological Characterization And Expression Analysis Of Genes For Horn And Hair Follicle Of Yak

Yak is a specific genetic resource in highland pastoral areas. Horn is the organization structure of bovine, and the self-defense weapons for animals struggle. However, in the process of modern intensive production, Horn become the restriction of animal production traits, because of its damage for animals and people. One reason of yak’s name is because of its long clothing hair and thick, which is the basis for adaptation of yak in alpine habitats, also to bring certain economic benefits for herders. Based on this, this article is going to studies on yak horn and hair follicle morphogenesis, and analysis their candidate genes. In order to providing scientific basis for yak molecular breeding and scientific management.The horn bud and forehead skin tissue from horn and polled yak of different gestational age were collected, through the preparation of frozen section, observe and contrast the formation and development of the horns; and analyzed the mRNA different expression of OLIG1, OLIG2, IFNAR1, IFNAR2, C1H21orf62, GCFC1, IFNGR2, SYNJ1, IL10 RB, GART, RXFP2, FOXL2, TWIST1, TWIST2, ZEB2, E-cadherin, P-cadherin genes using real-time quantitative PCR(qRT-PCR). Results show that the yak horn appears in the gestational age between 60~75days, the horn bud was white dots surround by the melanin particles in the early stage. With increasing gestational age, skin thickening performed that the keratinocytes of stratum spinosum cell vacuoles and the cellular layer increased, corneous layer is thick; Horn bud has no hair follicle development, hair bud when the gestational age is 135 days, it’s about 50 days later than the skin; and the polled yaks in the same gestational age no difference in stratum spinosum structure and skin. Candidate genes OLIG1, IFNAR1, C1H21orf62, SYNJ1, IL10 RB, GART, RXFP2, TWIST2 and E-cadherin gene showed no differences between horn and skin(P > 0.05). There are significant difference of IFNGR2, FOXL2, TWIST1 and P-cadherin gene between horn buds from horned and polled yaks(P < 0.05). IFNAR2 and GCFC1 had significant transcription difference in the expression of horn bud and skin(P < 0.05). OLIG2 and ZEB2 had highly significant transcription difference in horn bud expression(P < 0.01). We concluded that OLIG2 and FOXL2 might be the key candidate genes. ZEB2, TWIST1 and IFNGR2 might also involve in the formation of horn. P-cadherin might participate in development of horn.Observation Yak embryo tissue sections of the skin of the head, research on hair follicle morphogenesis. By the expressing of E-cadherin protein that performed in immunohistochemistry, analyze the expression level of protein. Using qRT-PCR method to comparing the mRNA transcription levels of E-cadherin gene in different month fetal head skin. Results showed that the fetal head skin begins to form primary hair buds in embryonic age of 60~70 days, and form the hair bulbs structure in the embryonic age of 130 days. Secondary hair follicles differentiation out from primary hair follicles in gestational age 80~90 days; Observed the parts of the fetal skin melanin gathering situations in different periods, the hair follicles differentiation was started from head, of which lower, eyebrows, eyelashes, and horn site are the most obvious; E-cadherin protein acts on the epidermis, dermis and hair follicles, high expressed in epidermis, and showed moderate positive expression in hair follicles. E-cadherin gene mRNA express an uptrend in different embryonic age of Yak skin hair follicle, and express an lower value at the embryonic age of 90 days, obviously below 70 days, 120 days and 130 days(P < 0.05). It suggests that E-cadherin gene is most likely involved in the development of Yak hair follicles.