Bench G S, Friz A M, Corzett M H, Morse D H, Balhorn R
Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, CA 94550, USA.
Cytometry. 1996 Apr 1;23(4):263-71. doi: 10.1002/(SICI)1097-0320(19960401)23:4<263::AID-CYTO1>3.0.CO;2-I.
The total amount of phosphorus and sulfur inside the nuclei of individual bull, stallion, hamster, human, and mouse sperm from fertile subjects has been measured using Particle Induced X-ray Emission (PIXE). Using the sulfur masses, we determined the total protamine (protamine 1 plus protamine 2) mass within the sperm nuclei of each species. Using the phosphorus masses, we determined the DNA mass present within the sperm nuclei of each species. The results reveal that although the relative proportion of protamine 1 to protamine 2 varies among the species examined, the total protamine mass to DNA mass ratio is similar in bull, stallion, hamster, and mouse sperm nuclei. In contrast, mature human sperm nuclei were found to contain significantly less protamine. This observation is consistent with other studies, which suggest that as much as 15% of the DNA in human sperm remain packaged by histones. Using the data obtained for bull sperm, the length of DNA that could be covered by each protamine 1 molecule in bull sperm has been estimated. Making the assumption that the size of the protamine 1 binding site on DNA is similar in the sperm of these species, the length of DNA covered by a single protamine 2 molecule also has been estimated.
利用粒子诱导X射线发射（PIXE）技术，对来自可育个体的公牛、种马、仓鼠、人类和小鼠精子细胞核内的磷和硫总量进行了测量。利用硫的含量，我们确定了每个物种精子细胞核内鱼精蛋白（鱼精蛋白1加鱼精蛋白2）的总量。利用磷的含量，我们确定了每个物种精子细胞核内DNA的含量。结果显示，尽管在所研究的物种中鱼精蛋白1与鱼精蛋白2的相对比例有所不同，但公牛、种马、仓鼠和小鼠精子细胞核中鱼精蛋白总量与DNA总量的比例相似。相比之下，发现成熟人类精子细胞核中的鱼精蛋白含量明显较少。这一观察结果与其他研究一致，这些研究表明，人类精子中多达15%的DNA仍由组蛋白包装。利用公牛精子获得的数据，估计了公牛精子中每个鱼精蛋白1分子所能覆盖的DNA长度。假设这些物种精子中DNA上鱼精蛋白1结合位点的大小相似，也估计了单个鱼精蛋白2分子所覆盖的DNA长度。
