IN THIS ISSUE
Summary: This Primer summarises our current understanding of the diversity of WT1 functions in mammalian tissues and organs and how WT1 mutations can lead to disease.
Summary: This Review describes the gene regulatory networks, signaling pathways, morphogenetic movements and cell dynamics underlying organogenesis of the mammalian pancreas.
STEM CELLS AND REGENERATION
Live fate-mapping of joint-associated fibroblasts visualizes expansion of cell contributions during zebrafish fin regeneration
Summary: In zebrafish, a tph1b-expressing population of fibroblast-like cells is restricted to the joints of uninjured fins but contributes more broadly during regeneration.
Linking the environment, DAF-7/TGFβ signaling and LAG-2/DSL ligand expression in the germline stem cell niche
Summary: In the C. elegans germline, a DAF-3 binding element is required for the distal tip cell Notch pathway response to the environment and to DAF-7/TGFβ signaling, modulating developmental expansion of the stem cell pool.
A novel function for the IκB inhibitor Cactus in promoting Dorsal nuclear localization and activity in the Drosophila embryo
Summary: During dorsoventral patterning of the Drosophila embryo, ventral and lateral aspects of the embryonic Dorsal/NFκB gradient can behave differently in response to variations in Cactus concentration.
PLCζ is the physiological trigger of the Ca2+ oscillations that induce embryogenesis in mammals but conception can occur in its absence
Highlighted article: In mice, PLCζ-null sperm fail to trigger the Ca2+ oscillations in eggs that normally initiate embryogenesis in mammals, resulting in polyspermy and subfertility but not sterility.
Loss of DNA methylation in zebrafish embryos activates retrotransposons to trigger antiviral signaling
Highlighted article: Globally hypomethylated uhrf1 and dnmt1 mutants mount an interferon response, marking epigenetically damaged cells for immune clearance and limiting transposon activity.
Asymmetric distribution of hypoxia-inducible factor α regulates dorsoventral axis establishment in the early sea urchin embryo
Highlighted article: Oxygen-sensitive hydroxylases regulate HIFα, and consequently nodal, asymmetry in the prospective dorsal and ventral blastula, providing positional bias for dorsoventral patterning.
Cas9-mediated excision of Nematostella brachyury disrupts endoderm development, pharynx formation and oral-aboral patterning
Summary: Brachyury is a key regulator of mesoderm, but is also found in diploblasts, which lack this tissue layer. Knockout experiments reveal its widespread effects on the endomesodermal gene regulatory network.
Summary: Branch elongation during Drosophila tracheal development mechanistically resembles MyoII-independent collective cell migration; tensile forces resulting from tip cell migration are reduced by cell elongation and passive stalk cell intercalation.
Summary: foxQ2 and six3 form a regulatory module at the top of the gene network governing anterior development of the Tribolium castaneum embryo.
Summary: Bmp4 activates the mesoderm progenitor gene network via key regulators, such as brachyury and Nkx1-2, and prevents premature differentiation to mesodermal-derived lineages.
TECHNIQUES AND RESOURCES
Summary: Dissecting the genetic programs in distinct regions of the pharyngeal arches illuminates the roles of Edn1 and Jagged-Notch signaling and identifies novel domain-specific genes in craniofacial patterning.