Evolutionary significance of the ring-like plastid nucleus in the primitive red alga Cyanidioschyzon merolae as revealed by drying.
Evolutionary significance of the ring-like plastid nucleus in the primitive red alga Cyanidioschyzon merolae as revealed by drying.
复制标题
通过干燥揭示原始红藻 Cyanidioschyzon merolae 中环状质体核的进化意义。
DOI：
10.1007/s00709-020-01496-y
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发表时间：
2020
期刊：
影响因子：
2.9
通讯作者：
H. Kuroiwa
中科院分区：
文献类型：
--
作者：
T. Kuroiwa;M. Ohnuma;Y. Imoto;F. Yagisawa;O. Misumi;N. Nagata;H. Kuroiwa
原生质体起源于一个自由生活的蓝藻祖先，并拥有自己的基因组--可能有几个DNA副本。这些基因组组织在位于中心位置的叶绿体核(CN型pt核)中，由先前存在的叶绿体通过二进制分裂产生。具有CN型pt核的祖先藻类分化为两个基本的真核生物谱系：具有圆形(CL型)pt核的红藻和具有分散的小(SN型)pt核的绿藻。虽然绿藻和植物中的pt-核的分子动力学正在被分析，但最初具有CN型pt-核的藻类转化为CL型的红藻的过程还没有被研究过。在这里，我们证明了原始红藻蓝藻中的CN-型铂核可以通过干燥而转变为CL-型，从而产生轻微的细胞膨胀。这一结果表明，CN型铂原子核是由CL型原子核的致密堆积形成的，这表明Ac。类秋海藻是红藻谱系的原始祖先。我们还观察到CL型铂核具有链状珠状结构。每个珠子很可能是一个很小的DNA单位，类似于褐藻中的CL型pt-核。因此，我们的结果是Ac。褐藻次生内生共生体的候选类分节藻。
Primary plastids originated from a free-living cyanobacterial ancestor and possess their own genomes—probably a few DNA copies. These genomes, which are organized in centrally located plastid nuclei (CN-type pt-nuclei), are produced from preexisting plastids by binary division. Ancestral algae with a CN-type pt-nucleus diverged and evolved into two basal eukaryotic lineages: red algae with circular (CL-type) pt-nuclei and green algae with scattered small (SN-type) pt-nuclei. Although the molecular dynamics of pt-nuclei in green algae and plants are now being analyzed, the process of the conversion of the original algae with a CN-type pt-nucleus to red algae with a CL-type one has not been studied. Here, we show that the CN-type pt-nucleus in the primitive red algaCyanidioschyzon merolaecan be changed to the CL-type by application of drying to produce slight cell swelling. This result implies that CN-type pt-nuclei are produced by compact packing of CL-type ones, which suggests that aC. merolae–like alga was the original progenitor of the red algal lineage. We also observed that the CL-type pt-nucleus has a chain-linked bead-like structure. Each bead is most likely a small unit of DNA, similar to CL-type pt-nuclei in brown algae. Our results thus suggest aC. merolae–like alga as the candidate for the secondary endosymbiont of brown algae.