Identification of chick rax/rx genes with overlapping patterns of expression during early eye and brain development

Ohuchi, Hideyo; Tomonari, Sayuri; Itoh, Hiroyuki; Matsukawa, Takashi; Noji, Sumihare

doi:10.1016/s0925-4773(99)00094-5

Cited by 60 publications

(50 citation statements)

References 9 publications

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“…4j) as seen in some laterality mutants (Bisgrove et al, 2000), although the expression was still asymmetric. No significant changes were detected in expression of a posterior-lateral marker cdx (Marom et al, 1997;Ehrman and Yutzey, 2001) and an anterior marker rax (Ohuchi et al, 1999) (not shown).…”

Section: Inhibition Of Midline Cell Death Results In Laterality Defectsmentioning

confidence: 91%

Cell death along the embryo midline regulates left–right sidedness

Kelly

Wei

Matsukawa

2002

Developmental Dynamics

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During embryogenesis, leftright sidedness is established by asymmetric expression of laterality genes. A recent model predicts the presence of a functional midline that divides the left side of the embryonic disc from the right side, separating left-and right-inducing signals. We show evidence that this midline is formed from a distinct population of cells within the primitive streak. Cells in the dorsal midline of the chick primitive streak display unique expression of the gastrulation markers fgf-8 and brachyury. These midline cells are fated to die, and dead cells remain in the midline during gastrulation. Inhibition of midline cell death compromises the early expression of laterality genes, such as shh and nodal and randomizes the direction of heart looping. We suggest that cell death along the primitive streak midline is a novel mechanism involved in the regulation of leftright asymmetry during early embryogenesis.

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Section: Inhibition Of Midline Cell Death Results In Laterality Defectsmentioning

confidence: 91%

Cell death along the embryo midline regulates left–right sidedness

Kelly

Wei

Matsukawa

2002

Developmental Dynamics

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“…cRax is detectable in the ectoderm anterior to Hensen's node at stage 4. During neurulation, cRax is expressed similarly to mice in the anterior neural folds in the prospective retina, and in the ventral forebrain (Ohuchi et al, 1999). cRaxL is expressed in the anterior neural ectoderm somewhat later than cRax.…”

Section: Conservation Of Structure and Expression Of Rx Genesmentioning

confidence: 97%

“…Recently a small family of paired-like homeobox genes that is critical for eye formation, the Rx/Rax (for Retinal homeobox) family, has been identified (Casarosa et al, 1997;Eggert et al, 1998;Furukawa et al, 1997b;Loosli et al, 2001;Mathers et al, 1997;Ohuchi et al, 1999).…”

Section: Initial Stages Of Vertebrate Eye Developmentmentioning

confidence: 99%

“…The structure of Rx genes is very conserved and since their discovery, they have been described in several vertebrate and invertebrate species including chicken, Xenopus, mouse, medaka, Drosophila, zebrafish, and human (Casarosa et al, 1997;Eggert et al, 1998;Furukawa et al, 1997b;Loosli et al, 2001;Mathers et al, 1997;Ohuchi et al, 1999). The number of Rx genes varies among different species, and generally ranges from one to three.…”

Section: Conservation Of Structure and Expression Of Rx Genesmentioning

confidence: 99%

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Regulation of vertebrate eye development by Rx genes

Bailey

El‐Hodiri²,

Zhang³

et al. 2004

Int. J. Dev. Biol.

156

127

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The paired-like homeobox-containing gene Rx has a critical role in the eye development of several vertebrate species including Xenopus, mouse, chicken, medaka, zebrafish and human. Rx is initially expressed in the anterior neural region of developing embryos, and later in the retina and ventral hypothalamus. Abnormal regulation or function of Rx results in severe abnormalities of eye formation. Overexpression of Rx in Xenopus and zebrafish embryos leads to overproliferation of retinal cells. A targeted elimination of Rx in mice results in a lack of eye formation. Mutations in Rx genes are the cause of the mouse mutation eyeless (ey1), the medaka temperature sensitive mutation eyeless (el) and the zebrafish mutation chokh. In humans, mutations in Rx lead to anophthalmia. All of these studies indicate that Rx genes are key factors in vertebrate eye formation. Because these results cannot be easily reconciled with the most popular dogmas of the field, we offer our interpretation of eye development and evolution.

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“…In particular, Xenopus has been successfully used to analyze eye development, with well-documented pathways for eye induction, lens formation, retinal pathfinding and vascularization (Holt, 1984;Henry and Grainger, 1990;Chien et al, 1993;Hirsch and Harris, 1997;Kenyon et al, 1999;Lupo et al, 2005). In addition, studies have reported the generation of ectopic eyes in tadpoles through surgical techniques, and more recently through embryonic microinjection of a number of 'eye control genes' including Pax6, Rx1, Otx2 and Six3 (Koo and Graziadei, 1995;Chow et al, 1999;Ohuchi et al, 1999;Ashery-Padan and Gruss, 2001;Kenyon et al, 2001;Sedohara et al, 2003;Bailey et al, 2004), as well as through modulation of bioelectrical determinants of organ identity (Pai et al, 2012). Ectopic eyes induced in the cranial region of tadpoles appear to extend 'cellular bridges' and axons towards the optic tecta of the host and these structures are maintained across metamorphosis into adulthood (Harris, 1986;Koo and Graziadei, 1995;Sedohara et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

Ectopic eyes outside the head inXenopustadpoles provide sensory data for light-mediated learning

Blackiston

Levin

2013

Journal of Experimental Biology

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SUMMARYA major roadblock in the biomedical treatment of human sensory disorders, including blindness, has been an incomplete understanding of the nervous system and its ability to adapt to changes in sensory modality. Likewise, fundamental insight into the evolvability of complex functional anatomies requires understanding brain plasticity and the interaction between the nervous system and body architecture. While advances have been made in the generation of artificial and biological replacement components, the brainʼs ability to interpret sensory information arising from ectopic locations is not well understood. We report the use of eye primordia grafts to create ectopic eyes along the body axis of Xenopus tadpoles. These eyes are morphologically identical to native eyes and can be induced at caudal locations. Cell labeling studies reveal that eyes created in the tail send projections to the stomach and trunk. To assess function we performed light-mediated learning assays using an automated machine vision and environmental control system. The results demonstrate that ectopic eyes in the tail of Xenopus tadpoles could confer vision to the host. Thus ectopic visual organs were functional even when present at posterior locations. These data and protocols demonstrate the ability of vertebrate brains to interpret sensory input from ectopic structures and incorporate them into adaptive behavioral programs. This tractable new model for understanding the robust plasticity of the central nervous system has significant implications for regenerative medicine and sensory augmentation technology.

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Identification of chick rax/rx genes with overlapping patterns of expression during early eye and brain development

Cited by 60 publications

References 9 publications

Cell death along the embryo midline regulates left–right sidedness

Cell death along the embryo midline regulates left–right sidedness

Regulation of vertebrate eye development by Rx genes

Ectopic eyes outside the head inXenopustadpoles provide sensory data for light-mediated learning

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