Algal affinity and possible life cycle of the early Cambrian acritarch. Yurtusia uniformis. from South China
Algal affinity and possible life cycle of the early Cambrian acritarch. Yurtusia uniformis. from South China
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藻类亲和力和早期寒武纪原源的可能生命周期。
DOI：
10.1111/pala.12491
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发表时间：
2020
期刊：
影响因子：
2.6
通讯作者：
Ben Yang
中科院分区：
文献类型：
--
作者：
Xiaodong Shang;Pengju Liu;Małgorzata Moczydłowska;Ben Yang
湖北长阳地区寒武系底部岩家河组中发现了大量保存完好的球形有机壁微体化石Yurtusia uniformis。薄而中空的突起在囊泡的双层壁之间延伸。首次在该属中观察到囊泡腔内的单个到多个内部体，代表生殖结构（分裂的子细胞）。囊泡壁上可能会出现一个小的圆形穿孔，以释放内部的体。保存在不同生命阶段的标本的形态分析显示，随着囊泡的大小增加，过程逐渐变长。内体（子细胞）在囊泡内经历多次连续分裂，伴随着囊泡和突起的同时生长。细胞的生长规律、子细胞的形成和释放以及现存藻类与所研究微体化石之间的显著形态相似性表明，Yurtusia uniformis可能是一种绿色微体藻类，与Trebouxiophyceae甚至Chlorellales（Chlorophyta）有密切关系。个体的生长和繁殖模式表明，单形钇单胞菌是一种活跃生长的营养细胞，而不是一种代谢惰性的包囊或休眠孢子。在现代绿藻生活史的基础上，提出了均匀叶星藻的营养生长和无性繁殖的生活史。多个内部细胞可能代表在无性繁殖期间由成熟的自孢子囊产生的自孢子，其随后在从打开的自孢子囊释放后发育成独立的年轻营养细胞。
Abundant, well‐preserved specimens of spheroidal organic‐walled microfossilYurtusia uniformisare reported from the basal Cambrian Yanjiahe Formation in the Changyang area of Hubei Province, South China. Thin and hollow processes extend between the double walls of the vesicle. The single to multiple internal bodies within the vesicle cavity are observed in the genus for the first time, representing reproductive structures (dividing daughter cells). A small circular perforation may occur on the vesicle wall to release the internal bodies. Morphological analyses of specimens preserved at various life stages reveal that processes gradually became longer as the vesicle grew in size. The internal bodies (daughter cells) underwent several successive divisions within the vesicle, which was accompanied by the simultaneous growth of both vesicle and processes. The regular growth of cells, formation and release of daughter cells, and the remarkable morphological similarity between extant algae and the studied microfossils suggest thatYurtusia uniformisis probably a green microalga that may be closely related to the Trebouxiophyceae or even Chlorellales (Chlorophyta). The growth and reproductive mode of individuals indicates thatY. uniformisis an actively growing vegetative cell of microalgae, rather than a metabolically inert cyst or resting spore. A life cycle involving vegetative growth and asexual reproduction is proposed forY. uniformison the basis of the life histories of modern chlorophytes. The multiple internal cells may represent autospores produced by a mature autosporangium during asexual reproduction, which subsequently developed into separate young vegetative cells after their release from the opened autosporangium.