Near chromosome-level genome assembly of the microsporidium Hamiltosporidium tvaerminnensis.

Microsporidia are intracellular parasitic fungi whose genomes rank among the smallest of all known eukaryotes. A number of outstanding questions remain concerning the evolution of their large-scale variation in genome architecture, responsible for genome size variation of more than an order of magnitude. This genome report presents the first near-chromosomal assembly of a large-genome microsporidium, Hamiltosporidium tvaerminnensis. Combined Oxford Nanopore, Pacific Biosciences (PacBio), and Illumina sequencing led to a genome assembly of 17 contigs, 11 of which represent complete chromosomes. Our assembly is 21.64 Mb in length, has an N50 of 1.44 Mb, and consists of 39.56% interspersed repeats. We introduce a novel approach in microsporidia, PacBio Iso-Seq, as part of a larger annotation pipeline for obtaining high-quality annotations of 3,573 protein-coding genes. Based on direct evidence from the full-length Iso-Seq transcripts, we present evidence for alternative polyadenylation and variation in splicing efficiency, which are potential regulation mechanisms for gene expression in microsporidia. The generated high-quality genome assembly is a necessary resource for comparative genomics that will help elucidate the evolution of genome architecture in response to intracellular parasitism. © The Author(s) 2023. Published by Oxford University Press on behalf of The Genetics Society of America.

Citation

Pascal Angst, Jean-François Pombert, Dieter Ebert, Peter D Fields. Near chromosome-level genome assembly of the microsporidium Hamiltosporidium tvaerminnensis. G3 (Bethesda, Md.). 2023 Sep 30;13(10)

Mesh Tags

PMID: 37565496

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