Three Substrains of the Cyanobacterium Anabaena sp Strain PCC 7120 Display Divergence in Genomic Sequences and hetC Function
Three Substrains of the Cyanobacterium Anabaena sp Strain PCC 7120 Display Divergence in Genomic Sequences and hetC Function
复制标题
蓝藻鱼腥藻 sp 菌株 PCC 7120 的三个亚株在基因组序列和 hetC 功能上表现出差异
DOI：
10.1128/jb.00076-18
复制
发表时间：
2018
影响因子：
3.2
通讯作者：
Xu Xudong
中科院分区：
文献类型：
--
作者：
Wang Yali;Gao Yuan;Gao Hong;Zhang Cheng-Cai;Xu Xudong
Anabaena sp.菌株pcc7120是异囊蓝藻细胞分化和模式分子研究的模式菌株。在研究同一生物体的不同实验室中，已经注意到异囊发育的细微差异。在这项研究中，在三个亚菌株的基因组中发现了360个突变，包括单核苷酸多态性（snp）、小插入/缺失（indel； 1至3 bp）、片段缺失和转位。由于基因组的多倍体性质和多细胞形态，异质/杂合碱基也被鉴定出来，但当用超声波将丝状碎片镀上后可以完全分离。在Anabaena sp.菌株PCC 7120的异囊形成过程中，hetcs是一个在发育细胞中上调的基因，在大约一半的其他异囊形成蓝藻中发现。Anabaena sp. PCC 7120的tchin3亚株失活导致不同的表型：形成异囊，分化细胞继续分裂，或同时存在异囊和分裂的分化细胞。这些突变体中phez - GFP的表达也表现出不同的绿色荧光蛋白（GFP）荧光模式。因此，这些基因的功能受到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。异囊形成是全球氮固定的重要细胞分化过程，我们对异囊形成的分子遗传学知识主要是基于对Anabaena sp.菌株PCC 7120的研究。在这里，我们发现该菌株正在进行快速的微进化，导致与杂种囊发育相关的某些基因（如hec）的表型变异。该研究提供了一个正在进行的微进化的例子，以多细胞多拷贝基因组微生物的多个异质/杂合单核苷酸多态性（snp）为标志。
Anabaena 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.hetCis a gene upregulated in developing cells during heterocyst formation in Anabaena sp. strain PCC 7120 and found in approximately half of other heterocyst-forming cyanobacteria. Inactivation ofhetCin 3 substrains of Anabaena 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 PhetZ-gfpin thesehetCmutants also showed different patterns of green fluorescent protein (GFP) fluorescence. Thus, the function ofhetCis influenced by the genomic background and epistasis and constitutes an example of evolution under way.IMPORTANCEOur knowledge about the molecular genetics of heterocyst formation, an important cell differentiation process for global N2fixation, is mostly based on studies with Anabaena 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 ashetC. This study provides an example for ongoing microevolution, marked by multiple heterogeneous/heterozygous single nucleotide polymorphisms (SNPs), in a multicellular multicopy-genome microorganism.