The Pelagophyceae are marine stramenopile algae that include Aureoumbra lagunensis and Aureococcus anophagefferens, two microbial species notorious for causing harmful algal blooms. Despite their ecological significance, relatively few genomic studies of pelagophytes have been carried out. To improve understanding of the biology and evolution of pelagophyte algae, we sequenced complete mitochondrial genomes for A. lagunensis (CCMP1510), Pelagomonas calceolata (CCMP1756), and five strains of Aureoc. anophagefferens (CCMP1707, CCMP1708, CCMP1850, CCMP1984, and CCMP3368) using Nanopore long-read sequencing. All pelagophyte mitochondrial genomes assembled into single, circular mapping contigs between 39,376 bp (P. calceolata) and 55,968 bp (A. lagunensis) in size. Mitochondrial genomes for the five Aureoc. anophagefferens strains varied slightly in length (42,401–42,621 bp) and were 99.4–100.0% identical. Gene content and order were highly conserved between the Aureoc. anophagefferens and P. calceolata genomes, with the only major difference being a unique region in Aureoc. anophagefferens containingDNA adenine and cytosine methyltransferase (dam/dcm) genes that appear to be the product of lateral gene transfer from a prokaryotic or viral donor. Although the A. lagunensis mitochondrial genome shares seven distinct syntenic blocks with the other pelagophyte genomes, it has a tandem repeat expansion comprising ∼40% of its length, and lacks identifiable rps19 and glycine tRNA genes. Laterally acquired self-splicing introns were also found in the 23S rRNA (rnl) gene of P. calceolata and the coxI gene of the five Aureoc. anophagefferens genomes. Overall, these data provide baseline knowledge about the genetic diversity of bloom-forming pelagophytes relative to nonbloom-forming species.

中文翻译：

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中层藻的线粒体基因组进化

Pelagophyceae 是海洋原生藻类，包括 Aureoumbra lagunensis 和 Aureococcus anophagefferens，这两种微生物物种因导致有害藻类大量繁殖而臭名昭著。尽管它们具有生态意义，但对上层植物的基因组研究相对较少。为了加深对浮游藻的生物学和进化的了解，我们对 A. lagunensis (CCMP1510)、Pelagomonas calceolata (CCMP1756) 和五种 Aureoc 菌株的完整线粒体基因组进行了测序。噬菌体（CCMP1707、CCMP1708、CCMP1850、CCMP1984 和 CCMP3368）使用 Nanopore 长读长测序。所有浮游植物线粒体基因组组装成大小在 39,376 bp (P. calceolata) 和 55,968 bp (A. lagunensis) 之间的单个圆形映射重叠群。五个 Aureoc 的线粒体基因组。anophagefferens 菌株的长度略有不同（42,401–42,621 bp），99.4–100.0% 相同。Aureoc 之间的基因内容和顺序高度保守。anophagefferens 和 P. calceolata 基因组，唯一的主要区别是 Aureoc 中的一个独特区域。噬菌体含有 DNA 腺嘌呤和胞嘧啶甲基转移酶 (dam/dcm) 基因，这些基因似乎是来自原核或病毒供体的横向基因转移的产物。尽管 A. lagunensis 线粒体基因组与其他浮游植物基因组共享七个不同的同线块，但它具有串联重复扩增，占其长度的 ∼40%，并且缺乏可识别的 rps19 和甘氨酸 tRNA 基因。在 P. calceolata 的 23S rRNA (rnl) 基因和五个 Aureoc 的 coxI 基因中也发现了横向获得的自剪接内含子。噬菌体基因组。全面的，