Faron Justyna, Bernaś Tytus, Sas-Nowosielska Hanna, Klag Jerzy
Department of Animal Histology and Embryology, University of Silesia, Katowice, Poland.
Lab. for Imaging Tissue Structure and Function, Nencki Institute of Experimental Biology, Warsaw, Poland.
PLoS One. 2015 Feb 11;10(2):e0117187. doi: 10.1371/journal.pone.0117187. eCollection 2015.
We examined six types of cells that form the ovary of the earthworm Dendrobena veneta ogonia, prooocytes, vitellogenic oocytes, trophocytes, fully grown postvitellogenic oocytes and somatic cells of the gonad. The quantitative stereological method revealed a much higher "volume density" of mitochondria in all of the types of germ-line cells except for the somatic cells. Fluorescent vital stain JC-1, however, showed a much higher oxidative activity of mitochondria in the somatic cells than in the germ-line cells. The distribution of active and inactive mitochondria within the studied cells was assessed using the computer program ImageJ. The analysis showed a higher luminosity of inactive mitochondria in all of the types of germ-line cells and a higher luminosity of active mitochondria in somatic cells. The OXPHOS activity was found in somatic cells mitochondria and in the peripheral mitochondria of the vitellogenic oocytes. The detection of reactive oxygen species (ROS) revealed a differentiated distribution of ROS in the different cell types. The amount of ROS substances was lower in somatic cells than in younger germ-line cells. The ROS level was also low in the cytoplasm of fully grown postwitellogenic oocytes. The distribution of the MnSOD enzyme that protects mitochondria against destructive role of ROS substances was high in the oogonia and in prooocytes and it was very high in vitellogenic and postvitellogenic oocytes. However, a much lower level of this protective enzyme was observed in the trophocytes and the lowest level was found in the cytoplasm of somatic cells. The lower mitochondrial activity and higher level of MnSOD activity in germ-line cells when compared to somatic cells testifies to the necessity of the organisms to protect the mitochondria of oocytes against the destructive role of the ROS that are produced during oxidative phosphorylation. The protection of the mitochondria in oocytes is essential for the transfer of healthy organelles to the next generation.
我们研究了构成蚯蚓Dendrobena veneta卵巢的六种细胞类型，即卵原细胞、初级卵母细胞、卵黄生成期卵母细胞、滋养细胞、完全成熟的卵黄生成后期卵母细胞以及性腺的体细胞。定量体视学方法显示，除体细胞外，所有生殖系细胞类型中的线粒体“体积密度”都高得多。然而，荧光活体染料JC-1显示，体细胞中线粒体的氧化活性比生殖系细胞中的高得多。使用计算机程序ImageJ评估了所研究细胞内活性和非活性线粒体的分布。分析表明，所有生殖系细胞类型中非活性线粒体的亮度较高，而体细胞中活性线粒体的亮度较高。在体细胞线粒体和卵黄生成期卵母细胞的外周线粒体中发现了氧化磷酸化活性。活性氧（ROS）的检测揭示了ROS在不同细胞类型中的差异分布。体细胞中ROS物质的含量低于较年轻的生殖系细胞。完全成熟的卵黄生成后期卵母细胞的细胞质中ROS水平也较低。保护线粒体免受ROS物质破坏作用的锰超氧化物歧化酶（MnSOD）在卵原细胞和初级卵母细胞中的分布较高，在卵黄生成期和卵黄生成后期卵母细胞中非常高。然而，在滋养细胞中观察到这种保护酶的水平要低得多，而在体细胞的细胞质中发现的水平最低。与体细胞相比，生殖系细胞中线粒体活性较低且MnSOD活性较高，这证明生物体有必要保护卵母细胞的线粒体免受氧化磷酸化过程中产生的ROS的破坏作用。保护卵母细胞中的线粒体对于将健康的细胞器传递给下一代至关重要。
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