References of "Brand-Saberi, B"
     in
Bookmark and Share    
Peer Reviewed
See detailDevelopment of the vertebral column: Morphogenesis and genes
Wilting, J; Müller, T S; Ebensperger, C et al

in Vorgel, R; Fanghaenel, J; Giebel, J (Eds.) Aspects of Teratologie (1996)

Detailed reference viewed: 70 (0 UL)
Peer Reviewed
See detailPax-1, a regulator of sclerotome development is induced by notochord and floor plate signals in avian embryos.
Ebensperger, C.; Wilting, J.; Brand-Saberi, B. et al

in Anatomy & Embryology (1995), 191(4), 297-310

Pax-1 encodes for a DNA-binding transcriptional activator that was originally discovered in murine embryos using a probe from the Drosophila paired-box-containing gene, gooseberry-distal. We have cloned ... [more ▼]

Pax-1 encodes for a DNA-binding transcriptional activator that was originally discovered in murine embryos using a probe from the Drosophila paired-box-containing gene, gooseberry-distal. We have cloned the avian Pax-1 gene as a basis for experimental studies of the induction of Pax-1 in the paraxial mesoderm. The amino acid sequence of the paired-domain is exactly the same in the quail and mouse, whereas outside the paired-domain there is 61% homology. Starting at about the eight-somite stage, quail Pax-1 is expressed in the paraxial mesoderm in a craniocaudal sequence. The unsegmented paraxial mesoderm and the two most recently formed somites do not express Pax-1. In the epithelial somite, the somitocoele cells and the cells of the ventral two-thirds of the epithelial wall are positive. As soon as the sclerotome is formed, only a subset of sclerotome cells expresses Pax-1. These are the cells that migrate towards the notochord to form the perinotochordal tube. Expression then becomes restricted to the intervertebral discs, the perichondrium of the vertebral bodies and the connective tissue surrounding the spinal ganglia. Additional expression domains are found in the scapula and the pelvic region, distinct areas of the head, and the epithelium of the second to the fourth visceral pouch. In later stages the thymus is positive. In vitro and in vivo experiments show that the notochord induces Pax-1 in the paraxial mesoderm, but limb bud mesoderm is not competent to respond to notochordal signals. Floor plate is also capable of inducing Pax-1 expression in sclerotome cells. Our studies show that in competent cells of the paraxial mesoderm, Pax-1 is a mediator of signals emanating from the notochord and the floor plate. [less ▲]

Detailed reference viewed: 63 (1 UL)
Peer Reviewed
See detailInitial steps of myogenesis in somites are independent of influence from axial structures.
Bober, E.; Brand-Saberi, B.; Ebensperger, C. et al

in Development (1994), 120(11), 3073-82

Formation of paraxial muscles in vertebrate embryos depends upon interactions between early somites and the neural tube and notochord. Removal of both axial structures results in a complete loss of ... [more ▼]

Formation of paraxial muscles in vertebrate embryos depends upon interactions between early somites and the neural tube and notochord. Removal of both axial structures results in a complete loss of epaxial myotomal muscle, whereas hypaxial and limb muscles develop normally. We report that chicken embryos, after surgical removal of the neural tube at the level of the unsegmented paraxial mesoderm, start to develop myotomal cells that express transcripts for the muscle-specific regulators MyoD and myogenin. These cells also make desmin, indicating that the initial steps of axial skeletal muscle formation can occur in the absence of the neural tube. However, a few days following the extirpation, the expression of MyoD and myogenin transcripts gradually disappears, and becomes almost undetectable after 4 days. From these observations we conclude that the neural tube is not required for the generation of the skeletal muscle cell lineage, but may support the survival or maitenance of further differentiation of the myotomal cell compartment. Notochord transplanted medially or laterally to the unsegmented paraxial mesoderm leads to a ventralization of axial structures but does not entirely prevent the early appearance of myoblasts expressing MyoD transcripts. However, the additional notochord inhibits subsequent development and maturation of myotomes. Taken together, our data suggest that neural tube promotes, and notochord inhibits, the process of myogenesis in axial muscles at a developmental step following the initial expression of myogenic bHLH regulators. [less ▲]

Detailed reference viewed: 118 (1 UL)
Peer Reviewed
See detailThe ventralizing effect of the notochord on somite differentiation in chick embryos.
Brand-Saberi, B.; Ebensperger, C.; Wilting, J. et al

in Anatomy & Embryology (1993), 188(3), 239-45

The dorso-ventral pattern formation of the somites becomes manifest by the formation of the epithelially organized dorsal dermomyotome and the mesenchymal ventrally situated sclerotome. While the ... [more ▼]

The dorso-ventral pattern formation of the somites becomes manifest by the formation of the epithelially organized dorsal dermomyotome and the mesenchymal ventrally situated sclerotome. While the dermomyotome gives rise to dermis and muscle, the sclerotome differentiates into cartilage and bone of the axial skeleton. The onset of muscle differentiation can be visualized by immunohistochemistry for proteins associated with muscle contractility, e.g. desmin. The sclerotome cells and the epithelial ventral half of the somite express Pax-1, a member of a gene family with a sequence similarity to Drosophila paired-box-containing genes. In the present study, changes of Pax-1 expression were studied after grafting an additional notochord into the paraxial mesoderm region. The influence of the notochord and the floor-plate on dermomyotome formation and myotome differentiation has also been investigated. The notochord is found to exert a ventralizing effect on the establishment of the dorso-ventral pattern in the somites. Notochord grafts lead to a suppression of the formation and differentiation of the dorsal somitic derivatives. Simultaneously, a widening of the Pax-1-expressing domain in the sclerotome can be observed. In contrast, grafted roof-plate and aorta do not interfere with dorso-ventral patterning of the somitic derivatives. [less ▲]

Detailed reference viewed: 49 (0 UL)