Biomedical subjects

Andrew Lumsden

Publications and source records attributed to Andrew Lumsden.

21 records · Page 2Linked to original sources

PubMed2002

The paired-type homeobox gene Dmbx1 marks the midbrain and pretectum.

We have isolated a paired-type homeobox gene Dmbx1, previously known as Atx (Development 128 (2001) 4789), from chick and mouse. Sequence similarity reveals that this gene is highly related to the Otx genes. Expression of Dmbx1 commences during gastrulation, when transcripts are detected in a crescent around the anterior neural plate. As development progresses, Dmbx1 marks the prospective midbrain and pretectum. Dmbx1 shares its caudal border of expression with Otx2, while expression is sharply delimited rostrally by the synencephalic-parencephalic boundary, later becoming restricted to the posterior synencephalon. At later stages, Dmbx1 is expressed in dynamic domains of the hindbrain and spinal cord. Additional sites of expression comprise stomodeal ectoderm and foregut endoderm, presomitic mesoderm, and the nasal pit.

Amino Acid Sequence↗

PubMed2002

The migration of cerebellar rhombic lip derivatives.

We have used cell labelling, co-culture and time-lapse confocal microscopy to investigate tangential neuronal migration from the rhombic lip. Cerebellar rhombic lip derivatives demonstrate a temporal organisation with respect to their morphology and response to migration cues. Early born cells, which migrate into ventral rhombomere 1, have a single long leading process that turns at the midline and becomes an axon. Later born granule cell precursors also migrate ventrally but halt at the lateral edge of the cerebellum, correlating with a loss of sensitivity to netrin 1 and expression of Robo2. The rhombic lip and ventral midline express Slit2 and both early and late migrants are repelled by sources of Slit2 in co-culture. These studies reveal an intimate relationship between birthdate, response to migration cues and neuronal fate in an identified population of migratory cells. The use of axons in navigating cell movement suggests that tangential migration is an elaboration of the normal process of axon extension.

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PubMedDate not supplied

Neural crest cells provide species-specific patterning information in the developing branchial skeleton.

The skeletal elements of the branchial region are made by neural crest cells, following tissue interactions with the pharyngeal endoderm. Previous transplantation experiments have claimed that the cranial neural crest is morphogenetically prespecified in respect of its branchial skeletal derivatives, that is, that information for the number, size, shape, and position of its individual elements is already determined in these cells when they are still in the neural folds. This positional information would somehow be preserved during delamination from the neural tube and migration into the branchial arches, before being read out as a spatial pattern of chondrogenesis and osteogenesis. However, it now appears that signals from the endoderm are able to specify not only the histogenic differentiation state of neural crest cells but also the identity and orientation of the branchial skeletal elements. It is therefore important to ask whether fine details of branchial skeletal pattern such as those that exist between different species are also governed by extrinsic factors, such as the endoderm, or by the neural crest itself. We have grafted neural crest between duck and quail embryos and show that the shape and size of the resulting skeletal elements is donor derived. The ability to form species-specific patterns of craniofacial skeletal tissue thus appears to be an inherent property of the neural crest, expressed as species-specific responses to endodermal signals.

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