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[P240]: Guidance of dopaminergic axonal projections in zebrafish
Author(s) -
Kastenhuber E.,
Ryu S.,
Driever W.
Publication year - 2006
Publication title -
international journal of developmental neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.761
H-Index - 88
eISSN - 1873-474X
pISSN - 0736-5748
DOI - 10.1016/j.ijdevneu.2006.09.299
Subject(s) - citation , library science , neuroscience , zebrafish , psychology , computer science , biology , genetics , gene
The PLAP secretory trap method was designed to identify novel transmembrane proteins with restricted expression in the developing mouse brain (Leighton et al., 2001). Previous studies utilising this method isolated a gene trap insertion in Tumour Endothelial Marker 7-related (TEM7R) which encodes a transmembrane protein with a structure and expression pattern suggestive of a role in axon guidance and organisation of the developing brain. In addition to a region of nidogen homology, the TEM7R protein contains a plexin repeat, a domain found in known axon guidance molecules such as Semaphorins and Plexins. We utilised Optical Projection Tomography (Sharpe et al., 2002) a new technique for 3D optical microscopy, to visualise early embryonic TEM7R expression in the mouse. Discrete TEM7R expression was found in the dorsal half of the eye and along the floor of the midbrain, as well as in the cortical hem and in the midbrain–hindbrain boundary, two of the major organising centres of the developing mammalian brain. TEM7R expression was also observed in a subset of peripherally projecting axons. At later stages of development, cellular and axonal reporter genes revealed TEM7R expression in a discrete subset of cells and tracts in the brain including the fimbria, stria terminalis, glial wedge, mamillary nuclei and a subset of thalamic nuclei. Binding of the extracellular portion of TEM7R was investigated through the production of an alkaline phosphatase tagged protein. This fusion protein was found to bind within the brain in a widespread but specific pattern. Homozygous TEM7R gene trap mutants did not survive to birth and lethality occurred at a stage precluding analysis of the role of TEM7R in brain development and axon guidance. To enable functional analyses, we are currently generating a conditional allele in the mouse and are investigating TEM7R expression in the chick with a view to manipulating its expression through in ovo electroporation techniques.