Departamento de Biología, Unidad de Genética, Universidad Autónoma de Madrid, 20849-Madrid, Spain.
Theriogenology. 2011 Jan 15;75(2):206-11. doi: 10.1016/j.theriogenology.2010.09.011. Epub 2010 Oct 30.
This study examined the dynamic response of Spermatozoa DNA Fragmentation after sex selection in bulls using a MoFlo(®) SX (Beckman Coulter, Miami FL) spermatozoa sorter. The dynamic response of spermatozoa DNA fragmentation refers to the changing values of SDF, i.e., rate of SDF (rSDF), when analyzed periodically over a set incubation time at 37 °C. A dynamic assessment of SDF using non-sorted and sex-sorted spermatozoa samples during 72 h of incubation at 37 °C was performed. Results showed a reduced DNA longevity in sex-sorted frozen-thawed spermatozoa, with spermatozoa DNA damage appearing between 24 h and 48 h. The baseline SDF level was higher in conventional frozen-thawed than in sex-sorted frozen-thawed spermatozoa samples; while the reverse occurred for the rSDF. The afore-mentioned result produced a crossover point between both dynamic tendencies of SDF for sex-sorted versus conventional samples. We defined this crossover point as the Crossover Positioning Time (CPT) or the time (in hours) where both curves crossover after a period of spermatozoa incubation at 37 °C. The point at which the CPT occurs could be used as an indicator of the rSDF for individual bulls after X- and Y-chromosome bearing spermatozoa selection. CPT values produced a window of SDF ranging between 24 h and 48 h in the present experiment. It is proposed that higher values for CPT are indicative of bulls presenting chromatin that is more resistant to the external stressors affecting spermatozoa DNA after spermatozoa sorting.
本研究使用 MoFlo(®)SX（贝克曼库尔特，迈阿密，佛罗里达州）精子分选仪检测了公牛精子性别选择后精子 DNA 碎片化的动态反应。精子 DNA 碎片化的动态反应是指在 37°C 孵育一定时间内，定期分析时 SDF 的变化值，即 SDF 率（rSDF）。在 37°C 孵育 72 小时期间，对非分选和性别分选的精子样本进行了 SDF 的动态评估。结果表明，在冷冻解冻的精子中，性别分选的精子 DNA 寿命缩短，精子 DNA 损伤出现在 24 小时至 48 小时之间。在常规冷冻解冻的精子样本中，基础 SDF 水平高于性别分选的冷冻解冻的精子样本；而 rSDF 则相反。上述结果产生了 SDF 对于性别分选和常规样本的两种动态趋势之间的交叉点。我们将这个交叉点定义为交叉定位时间（CPT），或者在 37°C 孵育一段时间后两条曲线交叉的时间（以小时为单位）。CPT 发生的时间点可以用作 X 染色体和 Y 染色体携带的精子选择后个体公牛 rSDF 的指标。CPT 值在本实验中产生了 24 小时至 48 小时之间的 SDF 窗口。提出更高的 CPT 值表明公牛的染色质对精子分选后影响精子 DNA 的外部应激因素更具抵抗力。
