In Xenopus, the Mix/Bix family of homeobox genes has been implicated in mesendoderm development. Mixl1 is the only known murine member of this family. To examine the role of Mixl1 in murine embryogenesis, we used gene targeting to create mice bearing a null mutation of Mixl1. Homozygous Mixl1 mutant embryos can be distinguished from their littermates by a marked thickening of the primitive streak. By the early somite stage, embryonic development is arrested, with the formation of abnormal head folds, foreshortened body axis, absence of heart tube and gut, deficient paraxial mesoderm, and an enlarged midline tissue mass that replaces the notochord. Development of extra-embryonic structures is generally normal except that the allantois is often disproportionately large for the size of the mutant embryo. In chimeras, Mixl1–/– mutant cells can contribute to all embryonic structures, with the exception of the hindgut, suggesting that Mixl1 activity is most crucial for endodermal differentiation. Mixl1 is therefore required for the morphogenesis of axial mesoderm, the heart and the gut during embryogenesis.
About us
Our publisher, The Company of Biologists, turns 100 this year. Read about the history of the Company and find out what Sarah Bray, our Chair of the Board of Directors, has to say.
Biologists @ 100 - join us in Liverpool in March 2025
We are excited to invite you to a unique scientific conference, celebrating the 100-year anniversary of The Company of Biologists, and bringing together our different communities. The conference will incorporate the Spring Meetings of the BSCB and the BSDB, the JEB Symposium Sensory Perception in a Changing World and a DMM programme on antimicrobial resistance. Find out more and register by 28 February 2025 to join us in March 2025 in Liverpool, UK.
Call for papers – Lifelong Development: the Maintenance, Regeneration and Plasticity of Tissues
Development invites you to submit your latest research to our upcoming special issue – Lifelong Development: the Maintenance, Regeneration and Plasticity of Tissues. This issue will be coordinated by Guest Editors Meritxell Huch (Max Planck Institute of Molecular Cell Biology and Genetics, Germany) and Mansi Srivastava (Harvard University and Museum of Comparative Zoology, USA), working alongside our team of academic Editors. Submit your articles by 15 May 2025.
A case for broadening our view of mechanism in developmental biology
In this Perspective, B. Duygu Özpolat and colleagues survey researchers on their views on what it takes to infer mechanism in developmental biology. They examine what factors shape our idea of what we mean by ‘mechanism’ and suggest a path forward that embraces a broad outlook on the diversity of studies that advance knowledge in our field.
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