This study investigated how the effects of photoperiod on circadian clock genes in the skin contribute to the regulation of hair follicle cycling of Inner Mongolia white cashmere goats. Twenty-four female (non-pregnant) Inner Mongolia white cashmere goats aged 1 - 1.5 years old with similar live weights (mean, 20.36 ± 2.63 kg) were randomly allocated into two groups: a natural daily photoperiod group (NDPP group:10 - 16 hr Light, n = 12) and a short daily photoperiod group (SDPP group: 7 hr Light:17 hr Dark, n = 12). All goats were housed in individual pens from May 15 to October 15, 2015 and were fed the same diets. We detected the mRNA expression of brain and muscle arnt-like protein-1 (Bmal1), circadian locomotor output control kaput (Clock), cryptochrome-1 (Cry1), period homolog-1 (Per1) and Rev-erbα genes in the goat skin. ANOVA revealed a significant 24 hr (10:00 hr, 14:00 hr, 18:00 hr, 22:00 hr, 02:00 hr, 06:00 hr, 10:00 hr) variation between the SDPP and NDPP groups for three months (July, September, and October). In summary, the current results confirm that an intrinsic oscillating molecular clock exists in goat skin, and that the clock is important for potential timing mechanisms at the anagen phase of hair follicles, which would contribute to the regulation mechanisms of hair follicle cell proliferation.

中文翻译：

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光周期对皮肤生物钟基因的影响有助于内蒙古白绒山羊毛囊循环的调控。

本研究探讨光周期对皮肤生物钟基因的影响如何促进内蒙古白绒山羊毛囊循环的调控。24只雌性（非妊娠）内蒙古白绒山羊，年龄1～1.5岁，活重相近（平均20.36±2.63 kg），随机分为两组：自然日光照组（NDPP组：10 - 16 小时光照，n = 12）和短日光周期组（SDPP 组：7 小时光照：17 小时黑暗，n = 12）。2015 年 5 月 15 日至 10 月 15 日期间，所有山羊都被圈养在单独的围栏中，并饲喂相同的日粮。我们检测了山羊大脑和肌肉 arnt-like protein-1 (Bmal1)、昼夜节律运动输出控制 kaput (Clock)、cryptochrome-1 (Cry1)、period homolog-1 (Per1) 和 Rev-erbα 基因的 mRNA 表达皮肤。方差分析显示 SDPP 和 NDPP 组在 24 小时（10:00 小时、14:00 小时、18:00 小时、22:00 小时、02:00 小时、06:00 小时、10:00 小时）之间存在显着差异三个月（七月、九月、十月）。总之，目前的结果证实山羊皮肤中存在内在振荡分子钟，并且该时钟对于毛囊生长期的潜在计时机制很重要，这将有助于毛囊细胞增殖的调节机制。