Ron A, Urieli S
J Protozool. 1977 Feb;24(1):150-4. doi: 10.1111/j.1550-7408.1977.tb05293.x.
In this study the characteristics of the synthesis of DNA and RNA in the nuclei of Loxodes were investigated. Loxodes striatus is a primitive ciliate with 2 pairs of structurally differentiated diploid nuclei, the macro- and micronuclei. The macronuclei and differentiated morphologically into a clearly recoginzable central core and an outer zone. To determine DNA and RNA synthesis, individual organisms were analyzed by autoradiography after incubating groups of cells with a 3H-labeled precursor ([3H]thymidine for DNA and [3H]uridine for RNA). The following observations were made: (A) All portions of macro- and micronuclei appeared to contain DNA as judged by the localizations of incorporated [3H]thymidine. (B) The macro- and micronuclei did not synthesize DNA at the same time; moreover, the duration of DNA synthesis in the former was much longer than of the latter nucleus. (C) Replication of DNA in the inner core and outer zone of the macronucleus occurred at separate times with little if any overlap. (D) All of the detectable [3H]uridine incorporation was found in the macronucleus and none in the micronucleus. Within the macronucleus the central core was more heavily labeled. (E) The quantitative differences in the label of the different components synthesis can occur in adult macronuclei. The possible explantion of these results is discussed in the context of the nuclear evolution of ciliates and of recent information on nuclear differentiation.
在本研究中，对斜管虫细胞核中DNA和RNA的合成特性进行了研究。条纹斜管虫是一种原始纤毛虫，具有两对结构上有差异的二倍体核，即大核和小核。大核在形态上分化为一个清晰可辨的中央核心和一个外部区域。为了确定DNA和RNA的合成，在用3H标记的前体（用于DNA的[3H]胸腺嘧啶核苷和用于RNA的[3H]尿嘧啶核苷）孵育细胞群后，通过放射自显影对单个生物体进行分析。得到了以下观察结果：（A）根据掺入的[3H]胸腺嘧啶核苷的定位判断，大核和小核的所有部分似乎都含有DNA。（B）大核和小核不同时合成DNA；此外，前者DNA合成的持续时间比后者长得多。（C）大核内核心和外部区域的DNA复制在不同时间发生，几乎没有重叠。（D）所有可检测到的[3H]尿嘧啶核苷掺入都发生在大核中，小核中未检测到。在大核内，中央核心标记更重。（E）不同成分合成标记的定量差异可能发生在成年大核中。在纤毛虫核进化以及核分化的最新信息背景下，讨论了这些结果的可能解释。
