ゼブラフィッシュは科学研究で良く用いられるモデル動物ですが、ヒトと違って胃がありません。ゼブラフィッシュに限らず、魚の中には胃を持たない種があります。アロワナ、なまず、ニジマス、タラ、カンパチ、メダカ、イトヨ、フグ、マンボウ、シーラカンスなどは胃を持たないようです。
もう少し詳しくいうと、条鰭類の科の7%、種の20~27%が無胃類で、進化の過程で胃の喪失はなんと独立に15回も起きていたと考えれています。
- 科学新聞2024年6月14日（金）胃持たない魚類 4遺伝子が決失 新たに4つの遺伝子（slc26a9, kcne2, cldn18a, vsig1)を見出した。
- Gastrointestinal transcription factors drive lineage-specific developmental programs in organ specification and cancer SCIENCE ADVANCES 11 Dec 2019 Vol 5, Issue 12 DOI: 10.1126/sciadv.aax8898 Sox2 is not only essential for gastric specification, by maintaining chromatin accessibility at forestomach lineage loci, but also sufficient to promote forestomach/esophageal transformation upon Cdx2 deletion.
- Stomach development, stem cells and disease 15 FEBRUARY 2016 Development (2016) 143 (4): 554–565. https://doi.org/10.1242/dev.124891 https://journals.biologists.com/dev/article/143/4/554/47787/Stomach-development-stem-cells-and-disease The transcription factors SOX2 and CDX2 define the sharp boundaries of the prospective stomach and intestine, possibly through mutual cross-antagonism. BARX1 is expressed specifically in mid-gestation stomach mesenchyme and induces secreted Wnt antagonists (sFRPs) to attenuate Wnt signaling, which ordinarily promotes intestinal development, in the overlying stomach epithelium.
- 学位論文 The origin of the vertebrate stomach and the paradox of loss Ferreira, Odete Marinho Gonçalves. Universidade do Porto (Portugal) ProQuest Dissertations & Theses, 2017. 10598508. https://www.proquest.com/openview/9bc990ae1b1563bd49833281ce3049ea/