C. elegans embryogenesis begins with a stereotyped sequence of asymmetric cell divisions that are largely responsible for establishing the nematode body plan. These early asymmetries are specified after fertilization by the widely conserved, cortically enriched PAR and PKC-3 proteins, which include three kinases and two PDZ domain proteins. During asymmetric cell divisions in the early embryo, centrosome pairs initially are positioned on transverse axes but then rotate to align with the anteroposterior embryonic axis. We show that rotation of the centrosomal/nuclear complex in an embryonic cell called P1 requires a maternally expressed gene we name spn-4. The predicted SPN-4 protein contains a single RNA recognition motif (RRM), and belongs to a small subfamily of RRM proteins that includes one Drosophila and two human family members. Remarkably, in mutant embryos lacking spn-4 function the transversely oriented ‘P1’ mitotic spindle appears to re-specify the axis of cell polarity, and the division remains asymmetric. spn-4 also is required for other developmental processes, including the specification of mesendoderm, the restriction of mesectoderm fate to P1 descendants, and germline quiescence during embryogenesis. We suggest that SPN-4 post-transcriptionally regulates the expression of multiple developmental regulators. Such SPN-4 targets might then act more specifically to generate a subset of the anterior-posterior asymmetries initially specified after fertilization by the more generally required PAR and PKC-3 proteins.
Interviews with Biologists @ 100 conference speakers
Explore our interviews with keynote speakers from the Biologists @ 100 conference, hosted to celebrate our publisher’s 100th anniversary, where we discuss climate change and biodiversity with Hans-Otto Pörtner and Jane Francis, health and disease with Charles Swanton and emerging technologies with Manu Prakash and Jennifer Lippincott-Schwartz.
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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