IN THIS ISSUE
Summary: This Hypothesis presents a mathematical approach to understanding periodic patterning during development, and suggests ways in which molecular, cellular or mechanical models can be tested.
Summary: This Review summarises our current understanding of the early stages of plant embryogenesis, with a focus on how the major lineages are specified.
STEM CELLS AND REGENERATION
The differential activation of intracellular signaling pathways confers the permissiveness of embryonic stem cell derivation from different mouse strains
Highlighted article: Different mouse strains show distinct JAK-Stat and MAPK activity responses to LIF treatment, accounting for the varying ease of generating stem cells from these lines.
Tetraspanin CD9 and ectonucleotidase CD73 identify an osteochondroprogenitor population with elevated osteogenic properties
Summary: High-throughput screening identifies a subpopulation of mouse mesenchymal progenitors with enhanced osteogenic capacity in both in vivo and in vitro assays.
A plant U-box protein, PUB4, regulates asymmetric cell division and cell proliferation in the root meristem
Highlighted article: The Arabidopsis E3 ubiquitin ligase PUB4 acts downstream of the CLV3/CLE peptides to regulate stem cell division and patterning in the growing root.
Summary: The Arabidopsis AIL and HDG transcription factors exert opposing roles in meristems, acting via physical interactions and shared downstream targets to control proliferation vs. differentiation.
Mediator Med23 deficiency enhances neural differentiation of murine embryonic stem cells through modulating BMP signaling
Summary: A component of the Mediator complex, which regulates RNA pol II activity, modulates BMP signalling to render stem cells less prone to differentiation down the neuronal lineage.
A computational model for the coordination of neural progenitor self-renewal and differentiation through Hes1 dynamics
Summary: Computational modelling deciphers the connections between the cell-cycle machinery and Notch signalling which govern whether neural stem cells proliferate, differentiate or enter quiescence.
Highlighted article: Growth cones from multiple neuronal types form F-actin-rich protrusions called invadosomes, which are necessary for axonal growth as motor neurons exit the spinal cord.
Highlighted article: In the developing fish caudal vein, β-catenin is activated by BMP in a Wnt-independent manner and cooperates with Aggf1 to control venous endothelial cell differentiation.
DNA hypomethylation induces a DNA replication-associated cell cycle arrest to block hepatic outgrowth in uhrf1 mutant zebrafish embryos
Summary: Uhrf1 recruits DNA methyltransferase 1; upon its mutation, cells show enhanced DNA replication but fail to proliferate and ultimately die - leading to reduced organ size.
Summary: Erbb3 knockout mice show cerebellar lamination and subsequent behavioural defects due to impaired proliferation of Bergmann glia - the scaffolds for granule neuron migration.
Summary: BMP signalling is transiently activated in the postnatal mouse retina to terminate the neurogenic program and promote the expression of glial-specific genes.
Surrounding tissues canalize motile cardiopharyngeal progenitors towards collective polarity and directed migration
Summary: Disrupting communication between migrating Ciona cardiac progenitors and their surrounding tissues reveals diverse mechanisms by which neighbouring cells influence directed migration in vivo.
Summary: A subset of cilia proteins are involved in intracellular trafficking of membrane-bound proteins, including planar cell polarity regulators, to non-ciliary locations.
A dynamic Shh expression pattern, regulated by SHH and BMP signaling, coordinates fusion of primordia in the amniote face
Summary: Iterative Shh and BMP signalling mechanisms induce a dynamic pattern of Shh expression in the mouse facial ectoderm that governs morphogenesis of the underlying mesenchyme.
Summary: In male primodial germ cells, depletion of Smad2 leads to loss of male-specific gene expression, while p38 is required for suppression of retinoic acid signalling and meiosis.
TECHNIQUES AND RESOURCES
A gene expression atlas of a bicoid-depleted Drosophila embryo reveals early canalization of cell fate
Summary: Drosophila bicoid mutant embryos show severe patterning phenotypes, but individual cells retain wild-type fates - as judged by expression of key patterning genes at single-cell resolution.
CoinFLP: a system for efficient mosaic screening and for visualizing clonal boundaries in Drosophila
Summary: A new Drosophila tool combines clonal analysis with Gal4/UAS-regulated transcription to enable high-throughput screening of gene knockdown or overexpression in mosaic tissues.