SummarySex selection through sperm sorting offers advantages in regards selection pressure in high-producing livestock. However, the sex-sorting process results in sperm membrane and DNA damage that ultimately decrease fertility. We hypothesized that given the role of protamines in DNA packaging, protamine deficiency could account, at least partially, for the DNA damage observed following sperm sex sorting. To test this, we compared protamine status between unsexed and sexed spermatozoa from two bulls using the fluorochrome chromomycin A3 (CMA3) and flow cytometry. Then, we assessed embryo development following in vitro fertilization (IVF) using the same sperm treatments. Overall, sperm protamination was not different between sexed and unsexed semen. However, one of the two bulls displayed higher rates of protamine deficiency for both unsexed and sexed semen (P < 0.05). Moreover, unsexed semen from this bull yielded lower blastocyst (P < 0.05) and blastocyst hatching rates than unsexed sperm from the other bull. CMA3-positive staining was negatively correlated with cleavage (R2 85.1, P = 0.003) and blastocyst hatching (R2 87.6, P = 0.006) rates in unsexed semen. In conclusion, while the sex-sorting process had no effect on sperm protamine content, we observed a bull effect for sperm protamination, which correlated to embryo development rates following IVF.

中文翻译：

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精子染色质 protamination 影响无性别和有性公牛精液中的胚胎发育

摘要通过精子分选的性别选择在高产牲畜的选择压力方面具有优势。然而，性别分选过程会导致精子膜和 DNA 损伤，最终降低生育能力。我们假设鉴于鱼精蛋白在 DNA 包装中的作用，鱼精蛋白缺乏可能至少部分地解释了精子性别分选后观察到的 DNA 损伤。为了测试这一点，我们使用荧光染料染色霉素 A3 (CMA3) 和流式细胞术比较了来自两只公牛的无性别和有性别精子之间的鱼精蛋白状态。然后，我们评估了以下胚胎发育体外使用相同的精子治疗进行受精（IVF）。总体而言，有性和无性精液之间的精子 protamination 没有差异。然而，两只公牛中的一只在无性别和有性别的精液中都表现出较高的鱼精蛋白缺乏率（磷< 0.05)。此外，这头公牛的无性别精液产生了较低的囊胚（磷< 0.05) 和囊胚孵化率高于其他公牛的未绝育精子。CMA3 阳性染色与卵裂呈负相关（R285.1,磷= 0.003) 和囊胚孵化 (R287.6,磷= 0.006) 无性别精液中的比率。总之，虽然性别分类过程对精子鱼精蛋白含量没有影响，但我们观察到精子鱼精蛋白的公牛效应，这与体外受精后的胚胎发育率相关。