Developmental Dynamics

Key findings:

• Undifferentiated ENCCs at the colorectal wavefront express HNK-1, N-cadherin, Sox10, p75, and L1CAM.

• ENCCs colonize the colorectum in a rostrocaudal direction during embryonic days 6.5–8.0 and subsequently differentiate rostrocaudally into neurons and glia.

• The results highlight a range of markers, including neuronal cell adhesion molecules, which can be used to label cells at the migration wavefront.

Key findings:

• Monopodial branching is not determined by autocrine morphogen gradients.

• TGFβ1 and BMP4 differentially affect branching and growth of the airways.

• Development of the airway epithelium obeys power-law dynamics.

• Branch sites scale with the size of the organ.

Key findings:

• Craniofacial perturbations in the Xenopus tadpole become normalized over time.

• The jaw and branchial arches achieve both normal position and morphology. Eyes, nose and otoliths achieve normal position but varying degrees of normal morphology.

• Two parameters, distance from the brain and angle from the midline, define normal position of craniofacial structures. Perturbed structures eventually achieve normal values for these parameters even though they start from abnormal initial conditions.

• These results shed light on the information processing and decision-making processes that underlie biological tissues' innate ability to repair deformities.

Key findings:

• dhx8 mutant fish are embryonic lethal.

• dhx8 mutant embryos have hematopoietic defects.

• dhx8 mutant embryos have cell division defects.

• dhx8 mutant embryos have RNA splicing defects.

Key findings:

• Mast cell abundance is up to ten-fold greater in the stroma surrounding ducts, compared to lobules; however, both structures show a peak at day 28 of age.

• Mast cell frequency in the lobule is significantly increased during diestrus II, the regressive phase of the estrous cycle.

• After peaking at day 2 of pregnancy, mast cell abundance declines steadily throughout pregnancy, but is rapidly restored to baseline levels in early post-lactational involution.

• Capillary abundance is cyclic in the resting gland terminal ductal lobular unit, with a peak during metestrus, when limited secretory differentiation occurs.

• Capillary abundance per lobular alveolus progressively increases throughout lactation, is maintained until day 2 of involution, progressively decreasing thereafter.

Key findings:

• Lissencephaly-1 is required for stem cell maintenance in planarians.

• Inhibition of Lissencephaly-1 leads to mitotic arrest and loss of the stem cell population.

• Lissencephaly-1 regulates the function of the mitotic spindle apparatus.

Key Findings:

• Mice lacking C/EBPα and C/EBPβ in the lung epithelium display impaired airway epithelial cell differentiation.

• Disruption of both Cebpa and Cebpb results in a more severe pulmonary phenotype than deletion of either gene alone.

• C/EBPα and C/EBPβ play partially overlapping roles in regulating airway epithelial differentiation.

Key findings:

• Twist1 regulates the development of the mandibular ramus.

• Twist1 regulates molar development and cusp formation.

• Mandibular hypoplasia causes cleft palate following a Pierre-Robin-like sequence.

• Twist1 controls the ossification of the mandible with Hand2.

Key Findings:

• Cyclin D1 is expressed in postnatal retinal progenitors.

• Fewer RPCs in Cyclin D1^−/− retina, but proliferation persists past the normal developmental period.

• Cyclin D3 is precociously expressed in Cyclin D1^−/− RPCs but doesn't compensate for loss of Cyclin D1.

• Altered production of late-born retinal cell types in Cyclin D1^−/− retina.

• Developmental timing of retinal histogenesis depends on aspects of Cyclin D1 function that are not shared by other D-cyclins.

Key findings:

• LPP3-deficiency reduces the amount of spinal neural precursors and neurons differentiated from embryonic stem cells.

• Absence of LPP3 decreases proliferation of neural precursors and increases apoptosis during the neural differentiation of embryoid bodies.

• Lack of LPP3 expression stimulates the differentiation of smooth muscle actin-expressing cells in ES cells differentiated under neuralizing conditions.

• Lack of LPP3 produces the accumulation of extracellular dihydro-S1P in embryoid bodies differentiated under neuralizing conditions.

• Lack of LPP3 in in vitro differentiated spinal neurons affects neurite outgrowth through the activation of Rho and PI3K.

Key findings:

• A new Cre/loxP system allows Gal4-dependent mosaic gene expression in various Drosophila tissues.

• This method efficiently induces mosaic gene expression in most embryonic tissues, including the epidermis, amnioserosa, tracheal system, malpighian tubules, foregut, and midgut. However, it is inefficient in neuronal tissue and does not occur in the visceral muscles.

• This method induces mosaic gene expression from embryonic stage 9.

Key findings:

• Disruption of pprc1 gene causes peri-implantation embryonic lethality. Developmental deficiencies in pprc1^−/− embryos occur during peri-implantation.

• In vitro culturing of pprc1^−/− blastocysts is susceptible to growth retardation.

• PPRC1 mRNA is expressed during preimplantation embryonic development.

• PPRC1 mRNA is rapidly up-regulated during early embryoid body formation.

Key findings:

• The expression pattern of Lzts1 in mouse and chick spinal cord is similar but not identical suggesting a fundamental and conserved embryonic function.

• Consistent with a potential role in cell cycle regulation/exit, Lzts1 mRNA is enriched in spinal neurons at the border of the ventricular and mantle zones.

• Lzts1 protein is expressed in motor, commissural and dorsal root ganglia axons and soma during periods of axon path finding and soma migration.

• Together, the profile of Lzts1 is consistent with a potential role(s) in cell cycle regulation, axon guidance, fasciculation, growth or neuronal migration.

Key findings:

• The expression pattern of each myogenic regulatory factor (MRF) during embryonic development highlights three successive myogenic waves in Xenopus somites.

• A first median and lateral myogenesis initiates before dermomyotome formation in Xenopus.

• Xenopus craniofacial myogenesis is characterized by the presence of Myf5- or Myod-lineages.

Key findings:

• EphB3 is expressed in pancreatic pro-endocrine cells, but not mature hormone producing cells.

• Detailed developmental expression pattern of EphB3 during first and secondary transition of pancreatic development suggest different differentiation rates.

• Pulse-chase techniques using an EphB3rtTA BAC-transgenic mice establishes the timeframe for embryonic endocrine cell maturation: ∼2 days.