University of the Ryukyus · Faculty of Science · 助教

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• Taxonomic insights and evolutionary history in East Asia terrestrial slugs of the genus Meghimatium2023 · Shun Ito, Daishi Yamazaki, Yuichi Kameda, Osamu Kagawa, Bin Ye, Takumi Saito, Kazuki Kimura, Van Tu Do, Satoshi Chiba, Takahiro Hirano
• Phylogenomic analyses reveal incongruences between divergence times and fossil records of freshwater snails in East Asia2023 · Takahiro Hirano, Takumi Saito, Shun Ito, Bin Ye, T. Mason Linscott, Do Van Tu, Zhengzhong Dong, Satoshi Chiba
• First report of the snail mite Riccardoella triodopsis (Acari: Ereynetidae) from Mainland China2023 · Tsukasa Waki, Takahiro Hirano, Bin Ye, Satoshi Shimano
• De novo genome assembly and genome skims reveal LTRs dominate the genome of a limestone endemic Mountainsnail (Oreohelix idahoensis)2022 · Abstract Background Calcareous outcrops, rocky areas composed of calcium carbonate (CaCO₃), often host a diverse, specialized, and threatened biomineralizing fauna. Despite the repeated evolution of physiological and morphological adaptations to colonize these mineral rich substrates, there is a lack of genomic resources for calcareous rock endemic species. This has hampered our ability to understand the genomic mechanisms underlying calcareous rock specialization and manage these threatened species. Results Here, we present a new draft genome assembly of the threatened limestone endemic land snail Oreohelix idahoensis and genome skim data for two other Oreohelix species. The O. idahoensis genome assembly (scaffold N50: 404.19 kb; 86.6% BUSCO genes) is the largest (~ 5.4 Gb) and most repetitive mollusc genome assembled to date (85.74% assembly size). The repetitive landscape was unusually dominated by an expansion of long terminal repeat (LTR) transposable elements (57.73% assembly size) which have shaped the evolution genome size, gene composition through retrotransposition of host genes, and ectopic recombination. Genome skims revealed repeat content is more than 2–3 fold higher in limestone endemic O. idahoensis compared to non-calcareous Oreohelix species. Gene family size analysis revealed stress and biomineralization genes have expanded significantly in the O. idahoensis genome. Conclusions Hundreds of threatened land snail species are endemic to calcareous rock regions but there are very few genomic resources available to guide their conservation or determine the genomic architecture underlying CaCO₃ resource specialization. Our study provides one of the first high quality draft genomes of a calcareous rock endemic land snail which will serve as a foundation for the conservation genomics of this threatened species and for other groups. The high proportion and activity of LTRs in the O. idahoensis genome is unprecedented in molluscan genomics and sheds new light how transposable element content can vary across molluscs. The genomic resources reported here will enable further studies of the genomic mechanisms underlying calcareous rock specialization and the evolution of transposable element content across molluscs.

• 小笠原諸島の陸産貝類保全2022 · 自然環境研究センター 寄附金
• 第31回（令和3年度）学術研究助成2022 · 昭和聖徳記念財団
• 東北大学 若手アンサンブルグラント2021 · 東北大学
• 笹川科学研究助成2021 · 日本科学協会

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