脊椎動物の交感神経系の起源に関する数十年にわたる誤解を覆す(Debunking a Decades-Long Misconception about the Origin of the Vertebrate Sympathetic Nervous System)

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2024-04-17 カリフォルニア工科大学(Caltech)

長年にわたり、ヤツメウナギには交感神経が存在しないと考えられていましたが、マリアンヌ・ブロナー教授の研究室での新たな発見により、この見解が覆されました。ヤツメウナギは発達の遅い段階で交感神経を持つことが判明し、交感神経系の進化に関する理解が更新されました。具体的には、ヤツメウナギの交感神経は受精後約1か月で現れ、ラルバ段階の4か月で成熟します。これは、他の脊椎動物と比較して極めて遅い発達であり、交感神経の形成が脊椎動物全体で進化的に保存されていることを示しています。

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脊椎動物の黎明期における交感神経ニューロンの神経堤起源 Neural crest origin of sympathetic neurons at the dawn of vertebrates

Brittany M. Edens,Jan Stundl,Hugo A. Urrutia & Marianne E. Bronner
Nature  Published:17 April 2024
DOI:https://doi.org/10.1038/s41586-024-07297-0

脊椎動物の交感神経系の起源に関する数十年にわたる誤解を覆す(Debunking a Decades-Long Misconception about the Origin of the Vertebrate Sympathetic Nervous System)

Abstract

The neural crest is an embryonic stem cell population unique to vertebrates1 whose expansion and diversification are thought to have promoted vertebrate evolution by enabling emergence of new cell types and structures such as jaws and peripheral ganglia2. Although jawless vertebrates have sensory ganglia, convention has it that trunk sympathetic chain ganglia arose only in jawed vertebrates3,4,5,6,7,8. Here, by contrast, we report the presence of trunk sympathetic neurons in the sea lamprey, Petromyzon marinus, an extant jawless vertebrate. These neurons arise from sympathoblasts near the dorsal aorta that undergo noradrenergic specification through a transcriptional program homologous to that described in gnathostomes. Lamprey sympathoblasts populate the extracardiac space and extend along the length of the trunk in bilateral streams, expressing the catecholamine biosynthetic pathway enzymes tyrosine hydroxylase and dopamine β-hydroxylase. CM-DiI lineage tracing analysis further confirmed that these cells derive from the trunk neural crest. RNA sequencing of isolated ammocoete trunk sympathoblasts revealed gene profiles characteristic of sympathetic neuron function. Our findings challenge the prevailing dogma that posits that sympathetic ganglia are a gnathostome innovation, instead suggesting that a late-developing rudimentary sympathetic nervous system may have been characteristic of the earliest vertebrates.

生物化学工学
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