Studies on the mitochondrial nucleoids in Euglena

(1)关于溴化乙锭和氯霉素对线粒体核样物质的影响，溴化乙锭(EB)处理10天后，细胞增殖停止，呼吸活性下降55%。线粒体大部分变细，有少量的冠状突起，有的呈杯状，有堆积的冠状突起。EB作用2天以上后，线粒体核团数量明显减少。EB处理3d后，约有一半的细胞未检测到线粒体核样物质。用CAP治疗10天后，呼吸活动减少47%。CAP不减少线粒体核团的数量，但增加了线粒体脊的数目和体积。(2)免疫电子显微镜检测到叶绿体和线粒体核团中的DNA，发现叶绿体中的核团由直径50-70 nm的缠绕丝状结构组成。缠绕的线缠绕在一起，形成直径100-200 nm的较厚的结节。线粒体中的类核团多为球形或卵圆形，直径70~130 nm。叶绿体和线粒体中的类核都含有与DNA线条紧密接触的核心。这些类核的外观结构与以前用常规电子显微镜观察到的结构有很大不同。

(1) Concerning the effects of ethidium bromide and chloramphenicol on the mitochondrial nucleoids.Ethidium bromide (EB) stopped the multiplication of cells and decreased their respiratory activity by 55% after treatment for 10 days. Most of the mitochondria became slender with few cristae and some became cup-shaped with stacked cristae. Mitochondrial nucleoids decreased markedly in number after treatment with EB for more than 2 days. After treatment for 3 days with EB, mitochondrial nucleoids could not be detected in about half of all cells examined. Treatment with CAP for 10 days reduced the respiratory activity by 47%. CAP did not decrease the number of mitochondrial nucleoids but it increased the number of cristae and the volume of mitochondria.(2) Concerning the detection of DNA in the nucleoids of chloroplasts and mitochondria by immunoelectron microscopy.Nucleoids in chloroplasts appeared to be composed of twisted threads of 50-70nm in diameter. The twisted threads were entangled to form thicker nodes of 100-200nm in diameter. Most nucleoids in mitochondria were spherical or ovoid, 70-130nm in diameter. Nucleoids both in chloroplasts and in mitochondria contained cores with which DNA threads were in tight contact. These apparent structures of nucleoids were very different from those previously observed by conventional electron microscopy.