Dual topologies of myotomal collagen XV and Tenascin C act in concert to guide and shape developing motor axons.

During development, motor axons are guided toward muscle target by various extrinsic cues including extracellular matrix (ECM) proteins whose identities and cellular source remain poorly characterized. Here, using single-cell RNAseq of sorted GFP cells from -injected zebrafish embryos, we unravel the slow muscle progenitors (SMP) pseudotemporal trajectory at the single-cell level and show that differentiating SMPs are a major source of ECM proteins. The SMP core-matrisome was characterized and computationally predicted to form a basement membrane-like structure tailored for motor axon guidance, including basement membrane-associated ECM proteins, as collagen XV-B, one of the earliest core-matrisome gene transcribed in differentiating SMPs and the glycoprotein Tenascin C.

A mechano- and heat-gated two-pore domain K channel controls excitability in adult zebrafish skeletal muscle.

TRAAK channels are mechano-gated two-pore-domain K channels. Up to now, activity of these channels has been reported in neurons but not in skeletal muscle, yet an archetype of tissue challenged by mechanical stress. Using patch clamp methods on isolated skeletal muscle fibers from adult zebrafish, we show here that single channels sharing properties of TRAAK channels, i.

Lack of the myotendinous junction marker col22a1 results in posture and locomotion disabilities in zebrafish.

The myotendinous junction (MTJ) is essential for the integrity of the musculoskeletal unit. Here, we show that gene ablation of the MTJ marker col22a1 in zebrafish results in MTJ dysfunction but with variable degrees of expression and distinct phenotypic classes. While most individuals reach adulthood with no overt muscle phenotype (class 1), a subset of the progeny displays severe movement impairment and die before metamorphosis (class 2).

Eye morphogenesis in the blind Mexican cavefish.

The morphogenesis of the vertebrate eye consists of a complex choreography of cell movements, tightly coupled to axial regionalization and cell type specification processes. Disturbances in these events can lead to developmental defects and blindness. Here, we have deciphered the sequence of defective events leading to coloboma in the embryonic eye of the blind cavefish of the species Astyanax mexicanus.

Fgfr3 Is a Positive Regulator of Osteoblast Expansion and Differentiation During Zebrafish Skull Vault Development.

Gain or loss-of-function mutations in fibroblast growth factor receptor 3 (FGFR3) result in cranial vault defects highlighting the protein's role in membranous ossification. Zebrafish express high levels of fgfr3 during skull development; in order to study FGFR3's role in cranial vault development, we generated the first fgfr3 loss-of-function zebrafish (fgfr3 ). The mutant fish exhibited major changes in the craniofacial skeleton, with a lack of sutures, abnormal frontal and parietal bones, and the presence of ectopic bones.