P. Macchi

Publications (2)2.83 Total impact

• Article: Partial respecification of nasotemporal polarity in double-temporal chick and chimeric chick-quail eyes.

  B K Mueller, D Dütting, A Haase, A Feucht, P Macchi
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  ABSTRACT: In chick embryos, naso-temporal polarity of the retina becomes established before Hamburger-Hamilton stage 10. To examine the plasticity of the early eye anlage, double-temporal eyes were made using stage 10-11 (E1.5) chick embryos and stage 8-9 quail embryos. In vivo and in vitro experiments revealed that these double-temporal compound eyes were not completely temporal but nasal in a large peripheral part of the graft. Four hours after transplantation, the nasal-specific fork head transcription factor CBF1 was not expressed in double-temporal eyes but was clearly detectable 24 h later. This suggests that in the peripheral part of the graft, temporal positional values were changed into nasal positional values by a respecification process.
  Mechanisms of Development 07/1998; 74(1-2):15-28. · 2.83 Impact Factor
• Article: RGM is a repulsive guidance molecule for retinal axons

  P P Monnier, A Sierra, P. Macchi, L. Deitinghoff, J S Andersen, M Mann, M. Flad, M R Hornberger, B Stahl, F Bonhoeffer, B K Mueller
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  ABSTRACT: Axons rely on guidance cues to reach remote targets during nervous system development(1). A well-studied model system for axon guidance is the retinotectal projection. The retina can be divided into halves; the nasal half, next to the nose, and the temporal half. A subset of retinal axons, those from the temporal half, is guided by repulsive cues expressed in a graded fashion in the optic tectum(2,3), part of the midbrain. Here we report the cloning and functional characterization of a membrane-associated glycoprotein, which we call RGM (repulsive guidance molecule). This molecule shares no sequence homology with known guidance cues, and its messenger RNA is distributed in a gradient with increasing concentration from the anterior to posterior pole of the embryonic tectum. Recombinant RGM at low nanomolar concentration induces collapse of temporal but not of nasal growth cones and guides temporal retinal axons in vitro, demonstrating its repulsive and axon-specific guiding activity.
  Nature, v.419, 392-395 (2002).