Chakrabarty Jitamanyu, Banerjee Dipankar, Pal Debasish, De Joydeep, Ghosh Amitabha, Majumder G C
Sperm Biology Division, Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Jadavpur, Kolkata 700 032, India.
Cryobiology. 2007 Feb;54(1):27-35. doi: 10.1016/j.cryobiol.2006.10.191. Epub 2007 Jan 16.
Membrane damage is one of the main reasons for reduced motility and fertility of sperm cells during cryopreservation. Using a model system of sperm cryopreservation developed in our laboratory, we have investigated the detailed changes due to cryopreservation in the plasma membrane lipid composition of the goat epididymal sperm cells. Total lipid and its components, i.e., neutral lipids, glycolipids and phospholipids decreased significantly after cryopreservation. Among neutral lipids sterols, steryl esters and 1-O-alkyl-2,3-diacyl glycerols decreased appreciably, while among phospholipids, major loss was observed for phosphatidyl choline and phosphatidyl ethanolamine. Unsaturated fatty acids bound to the phospholipids diminished while the percentage of saturated acids increased. The cholesterol:phospholipid ratio enhanced and the amount of hydrocarbon, which was unusually high, increased further on cryopreservation. The data indicates that profound increase of the hydrophobicity of the cell membrane is one of the major mechanisms by which spermatozoa acquire potential to resist or combat stress factors like cryodamage. The results are compatible with the view that for survival against cryodamage, sperm cells modulate the structure of their outer membrane by shedding off preferentially some hydrophilic lipid constituents of the cell membrane.
膜损伤是精子细胞在冷冻保存过程中活力和受精能力降低的主要原因之一。利用我们实验室开发的精子冷冻保存模型系统，我们研究了山羊附睾精子细胞质膜脂质组成因冷冻保存而发生的详细变化。冷冻保存后，总脂质及其成分，即中性脂质、糖脂和磷脂显著减少。在中性脂质中，固醇、固醇酯和1-O-烷基-2,3-二酰基甘油明显减少，而在磷脂中，磷脂酰胆碱和磷脂酰乙醇胺损失较大。与磷脂结合的不饱和脂肪酸减少，而饱和脂肪酸的百分比增加。胆固醇与磷脂的比例增加，冷冻保存后异常高的烃含量进一步增加。数据表明，细胞膜疏水性的显著增加是精子获得抵抗或对抗冷冻损伤等应激因素潜力的主要机制之一。这些结果与以下观点一致，即精子细胞为了抵抗冷冻损伤而存活，通过优先脱落细胞膜中一些亲水性脂质成分来调节其外膜结构。
