Kasimanickam R K, Kasimanickam V R, Arangasamy A, Kastelic J P
Department of Veterinary Clinical Sciences, Washington State University, Pullman, WA, 99164, USA.
Department of Veterinary Clinical Sciences, Washington State University, Pullman, WA, 99164, USA; Center for Reproductive Biology, Washington State University, Pullman, WA, 99164, USA.
Theriogenology. 2017 Feb;89:162-168. doi: 10.1016/j.theriogenology.2016.11.011. Epub 2016 Nov 16.
Mammalian sperm are exposed to a natural hypoosmotic environment during male-to-female reproductive tract transition; although this activates sperm motility in vivo, excessive swelling can harm sperm structure and function. Aquaporins (AQPs) is a family of membrane-channel proteins implicated in sperm osmoregulation. The objective was to determine associations among relative sperm volume shift, hypoosmotic swelling test (HOST), sperm aquaporin (AQP) 7 mRNA abundances, and sire conception rate (SCR; fertility estimate) in Holstein bulls at a commercial artificial insemination center. Three or four sires for each full point SCR score from -4 to +4 were included. Each SCR estimate for study bulls (N = 30) was based on > 500 services (mean ± SEM) of 725 ± 13 services/sire). Sperm from a single collection day (two ejaculates) from these commercial Holstein bulls were used. Relative mRNA expression of AQP7 in sperm was determined by polymerase chain reaction. Mean relative sperm volume shift and percentage of sperm reacted in a HOST (% HOST) were determined (400 sperm per bull) after incubating in isoosmotic (300 mOsm/kg) and hypoosmotic (100 mOsm/kg) solutions for 30 min. There was no correlation between %HOST and SCR (r = 0.28 P > 0.1). However, there was a positive correlation between relative sperm volume shift and SCR (r = 0.65, P < 0.05). Furthermore, AQP7 mRNA abundance was positively correlated to both relative volume shift (r = 0.73; P < 0.05) and to SCR (r = 0.67; P < 0.05). The mRNA expressions of AQP7 and relative sperm volume shift differed (P < 0.05) among low- (<2 SCR), average- (-2 to +2) and high- (>2) fertility sire groups. In conclusion, bulls with higher SCR had significantly greater AQP7 mRNA abundance in frozen-thawed sperm. This plausibly contributed to greater regulation of sperm volume shift, which apparently conferred protection from detrimental swelling and impaired functions.
在从雄性生殖道向雌性生殖道过渡的过程中，哺乳动物的精子会暴露于天然的低渗环境中；尽管这会在体内激活精子活力，但过度肿胀会损害精子的结构和功能。水通道蛋白（AQPs）是一类与精子渗透压调节有关的膜通道蛋白家族。本研究的目的是确定商业人工授精中心的荷斯坦公牛的相对精子体积变化、低渗肿胀试验（HOST）、精子水通道蛋白（AQP）7 mRNA丰度与 sire 受孕率（SCR；生育力估计值）之间的关联。纳入了SCR评分从-4到+4的每个完整评分点的三到四头公牛。研究公牛（N = 30）的每个SCR估计值基于> 500次输精（平均±SEM）（每头公牛725±13次输精）。使用了这些商业荷斯坦公牛单个采精日（两次射精）的精子。通过聚合酶链反应测定精子中AQP7的相对mRNA表达。在等渗（300 mOsm/kg）和低渗（100 mOsm/kg）溶液中孵育30分钟后，测定平均相对精子体积变化和HOST反应精子的百分比（%HOST）（每头公牛400个精子）。%HOST与SCR之间无相关性（r = 0.28，P>0.1）。然而，相对精子体积变化与SCR之间存在正相关（r = 0.65，P<0.05）。此外，AQP7 mRNA丰度与相对体积变化（r = 0.73；P<0.05）和SCR（r = （0.67；P<0.05）均呈正相关。低生育力（<2 SCR）、平均生育力（-2至+2）和高生育力（>2）公牛组之间，AQP7的mRNA表达和相对精子体积变化存在差异（P<0.05）。总之，SCR较高的公牛冻融精子中AQP7 mRNA丰度显著更高。这可能有助于更好地调节精子体积变化，从而明显保护精子免受有害肿胀和功能受损的影响。
