... in the nucleus, and deployment of guidance and adhesion cues to the cell surface. To identify genes involved in neurite targeting by retinal ganglion cells (GCs), their presynaptic partners in the retina, and their postsynaptic targets in the optic tectum, we undertook a forward genetic screen for mutations...

... are candidate regulators of this process in the dorsal midbrain (tectum) and anterior hindbrain (cerebellum). En1 mutants lack most of the tectum and cerebellum and die at birth, whereas En2 mutants are viable with a smaller cerebellum and foliation defects. Our previous studies indicated that the difference...

... midbrain, the future optic tectum. Wnts act both as patterning signals and as regulators of cell growth. In the developing tectum, Wnt signaling is mitogenic; however, the mechanism of Wnt function is not known. As a step towards better understanding this mechanism, we have identified two new Wnt targets...

...-specific conditional knockout of Lmx1b . As a result of these molecular defects, the development of the tectum and cerebellum was severely impaired in Lmx1b -/- mice. Taken together, our results indicate that Lmx1b plays an essential role in the development of the tectum and cerebellum by regulating...

... a distinct subset of retinal ganglion cells (RGCs),which project mainly into one of the four retinorecipient layers of the tectum and into a small subset of the extratectal arborization fields. In this transgenic line, we carried out an ENU-mutagenesis screen by scoring live zebrafish larvae for anatomical...

...Tatsuya Sato; Harukazu Nakamura The mes/metencephalic boundary (isthmus) is an organizing center for the optic tectum and cerebellum. Fgf8 is accepted as a crucial organizing signal. Previously, we reported that Fgf8b could induce cerebellum in the mesencephalon, while Fgf8a transformed...

... neocortex and tectum, whereas the Gli genes, which are targets and mediators of SHH signaling, are expressed in proliferative zones. In vitro and in vivo assays show that SHH is a mitogen for neocortical and tectal precursors and that it modulates cell proliferation in the dorsal brain. Together with its...

...Eiji Matsunaga; Isato Araki; Harukazu Nakamura Pax3/7 is expressed in the alar plate of the mesencephalon. The optic tectum differentiates from the alar plate of the mesencephalon, and expression of Pax3/7 is well correlated to the tectum development. To explore the function of Pax3 and Pax7...

..., the cerebellum differentiates in the metencephalon and the tectum differentiates in the mesencephalon. Based on the assumption that strong Fgf8 signal induces the cerebellum and that the Fgf8b signal is stronger than that of Fgf8a, we carried out experiments to misexpress Fgf8b and Fgf8a in chick embryos. Fgf8a...

...Yuji Watanabe; Harukazu Nakamura ABSTRACT Chick midbrain comprises two major components along the dorsoventral axis, the tectum and the tegmentum. The alar plate differentiates into the optic tectum, while the basal plate gives rise to the tegmentum. It is largely unknown how the differences...

... organizer in acerebellar mutants, which lack a MHB and cerebellum, but retain a tectum, and are mutant for fgf8 , a candidate inducer and polarizer. We examine the retinotectal projection in the mutants to assay polarity in the tectum. In mutant tecta, retinal ganglion cell (RGC) axons form overlapping...

... added exogenously to the developing Xenopus optic pathway, severely disrupt target recognition causing axons from the retina to bypass their primary target, the optic tectum. Significantly, HS sidechains from a neuro-epithelial perlecan variant that preferentially bind FGF-2, HS(FGF-2), cause aberrant...

... degeneration mutants. These 18 mutants have restricted cell death mainly in the tectum and the dorsal hindbrain after 36 hours. The degeneration does not spread and disappears at later stages of development. Class II: early focal neural degeneration mutants. Ten mutants in this class exhibit transient...

... have isolated mutants in the zebrafish Danio rerio that have defects in axonal connectivity between the retina and tectum. 5-day-old fish larvae were screened by labeling retinal ganglion cells with DiI and DiO and observing their axonal projections to and on the tectum. 82 mutations, representing 13...

... to the target position; such pathways are in no way characteristic of actually observed axonal pathways (see Fig. 4 ). In some cases where individual fibres invading the tectum have been traced, considerable meandering was observed with respect to the pathway. This applies especially to misrouted...

...William A. Harris; Christine E. Holt; Friedrich Bonhoeffer ABSTRACT Time-lapse video recordings were made of individual retinal ganglion cell fibres growing to and terminating in the optic tectum of Xenopus embryos. The fibres were stained by inserting a crystal of the lipophilic fluorescent dye...