State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, China.
Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, China.
J Bacteriol. 2018 Jun 11;200(13). doi: 10.1128/JB.00076-18. Print 2018 Jul 1.
sp. strain PCC 7120 is a model strain for molecular studies of cell differentiation and patterning in heterocyst-forming cyanobacteria. Subtle differences in heterocyst development have been noticed in different laboratories working on the same organism. In this study, 360 mutations, including single nucleotide polymorphisms (SNPs), small insertion/deletions (indels; 1 to 3 bp), fragment deletions, and transpositions, were identified in the genomes of three substrains. Heterogeneous/heterozygous bases were also identified due to the polyploidy nature of the genome and the multicellular morphology but could be completely segregated when plated after filament fragmentation by sonication. is a gene upregulated in developing cells during heterocyst formation in sp. strain PCC 7120 and found in approximately half of other heterocyst-forming cyanobacteria. Inactivation of in 3 substrains of sp. PCC 7120 led to different phenotypes: the formation of heterocysts, differentiating cells that keep dividing, or the presence of both heterocysts and dividing differentiating cells. The expression of P - in these mutants also showed different patterns of green fluorescent protein (GFP) fluorescence. Thus, the function of is influenced by the genomic background and epistasis and constitutes an example of evolution under way. Our knowledge about the molecular genetics of heterocyst formation, an important cell differentiation process for global N fixation, is mostly based on studies with sp. strain PCC 7120. Here, we show that rapid microevolution is under way in this strain, leading to phenotypic variations for certain genes related to heterocyst development, such as This study provides an example for ongoing microevolution, marked by multiple heterogeneous/heterozygous single nucleotide polymorphisms (SNPs), in a multicellular multicopy-genome microorganism.
sp. 菌株 PCC 7120 是研究异形胞形成蓝藻细胞分化和模式形成的模式菌株。在同一生物体内，不同实验室在研究异形胞发育时注意到了细微的差异。在这项研究中，在三个亚菌株的基因组中鉴定出 360 个突变，包括单核苷酸多态性 (SNP)、小插入/缺失 (indel; 1 至 3 bp)、片段缺失和转座。由于基因组的多倍体性质和多细胞形态，也鉴定出了异质/杂合碱基，但通过超声处理丝状断裂后平板培养，可以完全分离。 是 sp. 菌株 PCC 7120 异形胞形成过程中发育细胞上调的基因，在大约一半的其他异形胞形成蓝藻中发现。在 3 个 sp. PCC 7120 亚菌株中失活 导致不同的表型：异形胞的形成、不断分裂的分化细胞、或异形胞和分裂分化细胞的存在。这些突变体中 P 的表达也显示出不同的绿色荧光蛋白 (GFP) 荧光模式。因此， 的功能受基因组背景和上位性的影响，构成了正在进行的进化的一个例子。我们对异形胞形成的分子遗传学的了解，这是全球氮固定的一个重要细胞分化过程，主要基于对 sp. 菌株 PCC 7120 的研究。在这里，我们表明这种菌株正在进行快速的微观进化，导致与异形胞发育相关的某些基因的表型变异，例如 这项研究为正在进行的微观进化提供了一个例子，其标志是多细胞多拷贝基因组微生物中存在多种异质/杂合单核苷酸多态性 (SNP)。
