2025-12-11 筑波大学
図1 ヌタウナギ(Eptatretus burgeri)の外観と、ひだ状構造を持つ嗅覚器:ひだの両側⾯に嗅神経細胞が分布する。
<関連情報>
- https://www.tsukuba.ac.jp/journal/biology-environment/20251211140000.html
- https://www.tsukuba.ac.jp/journal/pdf/p20251211140000.pdf
- https://www.cell.com/iscience/fulltext/S2589-0042(25)02379-X
ヌタウナギ嗅覚レパートリーが基盤的脊椎動物の嗅覚の系統特異的多様化を明らかにする Hagfish olfactory repertoire illuminates lineage-specific diversification of olfaction in basal vertebrates
Hirofumi Kariyayama ∙ Yusuke Ooi ∙ Hiromu Kashima ∙ … ∙ Riho Harada ∙ Yoko Yamaguchi ∙ Daichi G. Suzuki
iScience Published:November 18, 2025
DOI:https://doi.org/10.1016/j.isci.2025.114118
Highlights
- Genomic and expression analyses reveal hagfish olfactory repertoire
- V2Rs are extensively diversified in hagfish
- Olfactory function of V2Rs is traced back to the common ancestor of vertebrates
- Olfactory repertoires of basal vertebrates underwent lineage-specific evolution
Summary
Chemosensory receptors for olfaction of vertebrates have undergone remarkable diversification, but the ancestral repertoire remains incompletely understood. Here, we present a comprehensive genome-wide survey and gene expression analyses of the olfactory repertoire in hagfish, a cyclostome group that typically inhabits the deep sea with a well-developed olfactory system. We identified 48 olfactory receptors (ORs), two vomeronasal type 1 receptors (V1Rs), 135 typical vomeronasal type 2 receptors (V2Rs), and no trace amine-associated receptors (TAARs) in the inshore hagfish, Eptatretus burgeri. Expression analysis confirmed that most of these genes are expressed predominantly in the olfactory organ, supporting that these receptors are functional. Our findings suggest that typical olfactory V2Rs were present in the common ancestor of all vertebrates. This study highlights the evolution of vertebrate olfaction in a lineage-specific manner, underscoring the importance of hagfish as a key animal for reconstructing the evolutionary history of early vertebrates.
