Institute of Automation and Electrometry, the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia.
Institute of Automation and Electrometry, the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia; Institute of Cytology and Genetics, the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia.
Biophys J. 2021 Dec 21;120(24):5619-5630. doi: 10.1016/j.bpj.2021.11.008. Epub 2021 Nov 10.
Cryopreservation of oocytes has already been used to preserve genetic resources, but this technology faces limitations when applied to the species whose oocytes contain large amounts of cytoplasmic lipid droplets. Although cryoinjuries in such oocytes are usually associated with the lipid phase transition in lipid droplets, this phenomenon is still poorly understood. We applied Raman spectroscopy of deuterium-labeled lipids to investigate the freezing of lipid droplets inside cat oocytes. Lipid phase separation was detected in oocytes cryopreserved by slow-freezing protocol. For oocytes supplemented with stearic acid, we found that saturated lipids form the ordered phase being distributed at the periphery of lipid droplets. When an oocyte is warmed to physiological temperatures after cooling, a fraction of saturated lipids may remain in the ordered conformational state. The fractions of monounsaturated and polyunsaturated lipids redistribute to the core of lipid droplets. Monounsaturated lipids undergo the transition to the ordered conformational state below -10°C. Using deuterated fatty acids with a different number of double bonds, we reveal how different lipid fractions are involved in the lipid phase transition of a cytoplasmic lipid droplet and how they can affect cell survival. Raman spectroscopy of deuterated lipids has proven to be a promising tool for studying the lipid phase transitions and lipid redistributions inside single organelles within living cells.
卵母细胞的冷冻保存技术已被用于保存遗传资源，但该技术在应用于卵母细胞中含有大量细胞质脂滴的物种时存在局限性。虽然此类卵母细胞中的冷冻损伤通常与脂滴中的脂质相转变有关，但这一现象仍知之甚少。我们应用氘标记脂质的拉曼光谱研究了猫卵母细胞中脂质滴的冷冻。在慢速冻协议冷冻保存的卵母细胞中检测到脂质相分离。对于用硬脂酸补充的卵母细胞，我们发现饱和脂质形成有序相，分布在脂滴的外围。当卵母细胞冷却后在生理温度下变暖时，一部分饱和脂质可能仍处于有序构象状态。单不饱和和多不饱和脂质的分数重新分布到脂滴的核心。单不饱和脂质在-10°C 以下转变为有序构象状态。使用具有不同双键数的氘化脂肪酸，我们揭示了不同的脂质分数如何参与细胞质脂滴的脂质相转变，以及它们如何影响细胞存活。氘化脂质的拉曼光谱已被证明是研究活细胞内单个细胞器内脂质相转变和脂质重分布的有前途的工具。
