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Developing Eye (developing + eye)
Selected AbstractsIdentification of Tgf,1i4 as a downstream target of Foxc1DEVELOPMENT GROWTH & DIFFERENTIATION, Issue 5 2006Paula Sommer Craniofacial development is severely affected by null mutations in Foxc1, indicating a multifunctional role for Foxc1 in ocular, maxilla and mandible, skull and facial gland development. To delineate signaling pathways in which Foxc1 is involved we compared the transcriptomes of whole heads of Foxc1+/+ and Foxc1,/, embryos using a candidate cDNA array comprising genes expressed in the head mesenchyme and ocular region, and a 7K oligo array. Absence of Foxc1 led to downregulation of Stat1 and Galnt4, and upregulation of Tgf,1i4 at embryonic day 13.5 in the developing head mesenchyme. Comparative analyses revealed differences in the expression pattern of Tgf,1i4 in the head mesenchyme of Foxc1,/, and Foxc1+/+ embryos. In the ocular regions of Foxc1,/, embryos, Tgf,1i4 was expressed in higher levels in the conjunctival epithelium and in the condensing mesenchyme on the nasal aspect of the developing eye while in wild-type embryos more intense expression was seen in the mesenchyme on the temporal aspect of the eye. Such data indicate that Foxc1 regulation of Tgf,1i4 is complex and may be cell-type dependent. Analysis of the regulation of Tgf,1i4 by Foxc1 in a more homogenous cell population, mesenchymal cells isolated from the periocular region revealed that, in these cells, Foxc1 negatively regulated Tgf,1i4 expression, presumably via secreted factors such as TGF-,1. Since Foxc1 expression is essential for normal craniofacial development, it is possible that its downstream targets play a role in the development of the phenotypes associated with null mutations in Foxc1. [source] Identification of genes expressed preferentially in the developing peripheral margin of the optic cupDEVELOPMENTAL DYNAMICS, Issue 9 2009Jeffrey M. Trimarchi Abstract Specification of the peripheral optic cup by Wnt signaling is critical for formation of the ciliary body/iris. Identification of marker genes for this region during development provides a starting point for functional analyses. During transcriptional profiling of single cells from the developing eye, two cells were identified that expressed genes not found in most other single cell profiles. In situ hybridizations demonstrated that many of these genes were expressed in the peripheral optic cup in both early mouse and chicken development, and in the ciliary body/iris at subsequent developmental stages. These analyses indicate that the two cells probably originated from the developing ciliary body/iris. Changes in expression of these genes were assayed in embryonic chicken retinas when canonical Wnt signaling was ectopically activated by CA-,-catenin. Twelve ciliary body/iris genes were identified as upregulated following induction, suggesting they are excellent candidates for downstream effectors of Wnt signaling in the optic cup. Developmental Dynamics 238:2327,2339, 2009. © 2009 Wiley-Liss, Inc. [source] Expression patterns of the opsin 5,related genes in the developing chicken retinaDEVELOPMENTAL DYNAMICS, Issue 7 2008Sayuri Tomonari Abstract The opsin gene family encodes G protein,coupled seven-transmembrane proteins that bind to a retinaldehyde chromophore for photoreception. It has been reported that opsin 5 is expressed in mammalian neural tissue, but its function has been elusive. As a first step to understand the function for opsin 5 in the developing eye, we searched for chicken opsin 5 -related genes in the genome by a bioinformatic approach and isolated opsin 5 cDNA fragments from the embryonic retina by RT-PCR. We found that there are three opsin 5,related genes, designated cOpn5m (chicken opsin 5, mammalian type), cOpn5L1 (chicken opsin 5 - like 1), and cOpn5L2 (chicken opsin 5 - like 2), in the chicken genome. Quantitative PCR analysis has revealed that cOpn5m is the most abundant in the developing and early posthatching neural retina. In situ hybridization analysis has shown that cOpn5m is specifically expressed in subsets of differentiating ganglion cells and amacrine cells. These results suggest that the mammalian type opsin 5 may contribute to the development of these retinal cells in the chicken. Developmental Dynamics 237:1910,1922, 2008. © 2008 Wiley-Liss, Inc. [source] Skeletal elements in the vertebrate eye and adnexa: Morphological and developmental perspectivesDEVELOPMENTAL DYNAMICS, Issue 5 2006Tamara A. Franz-Odendaal Abstract Although poorly appreciated, the vertebrate eye and adnexa are relatively common sites for skeletogenesis. In many taxa, the skeleton contributes to internal reinforcement in addition to the external housing of the eye (e.g., the circumorbital bones and eyelids). Eyeball elements such as scleral cartilage and scleral ossicles are present within a broad diversity of vertebrates, albeit not therian mammals, and have been used as important models for the study of condensations and epithelial,mesenchymal interactions. In contrast, other elements invested within the eye or its close surroundings remain largely unexplored. The onset and mode of development of these skeletal elements are often variable (early versus late; involving chondrogenesis, osteogenesis, or both), and most (if not all) of these elements appear to share a common neural crest origin. This review discusses the development and distribution of the skeletal elements within and associated with the developing eye and comments on homology of the elements where these are questionable. Developmental Dynamics 235:1244,1255, 2006. © 2006 Wiley-Liss, Inc. [source] Neuronal leucine-rich repeat 6 (XlNLRR-6) is required for late lens and retina development in Xenopus laevisDEVELOPMENTAL DYNAMICS, Issue 4 2006Adam D. Wolfe Abstract Leucine-rich repeat proteins expressed in the developing vertebrate nervous system comprise a complex, multifamily group, and little is known of their developmental function in vivo. We have identified a novel member of this group in Xenopus laevis, XlNLRR-6, and through sequence and phylogenetic analysis, have placed it within a defined family of vertebrate neuronal leucine-rich repeat proteins (NLRR). XlNLRR-6 is expressed in the developing nervous system and tissues of the eye beginning at the neural plate stage, and expression continues throughout embryonic and larval development. Using antisense morpholino oligonucleotide (MO) -mediated knockdown of XlNLRR-6, we demonstrate that this protein is critical for development of the lens, retina, and cornea. Reciprocal transplantation of presumptive lens ectoderm between MO-treated and untreated embryos demonstrate that XlNLRR-6 plays autonomous roles in the development of both the lens and retina. These findings represent the first in vivo functional analysis of an NLRR family protein and establish a role for this protein during late differentiation of tissues in the developing eye. Developmental Dynamics 235:1027,1041, 2006. © 2006 Wiley-Liss, Inc. [source] The fabp4 gene of zebrafish (Danio rerio) , genomic homology with the mammalian FABP4 and divergence from the zebrafish fabp3 in developmental expressionFEBS JOURNAL, Issue 6 2007Rong-Zong Liu Teleost fishes differ from mammals in their fat deposition and distribution. The gene for adipocyte-type fatty acid-binding protein (A-FABP or FABP4) has not been identified thus far in fishes. We have determined the cDNA sequence and defined the structure of a fatty acid-binding protein gene (designated fabp4) from the zebrafish genome. The polypeptide sequence encoded by zebrafish fabp4 showed highest identity to the Had -FABP or H6-FABP from Antarctic fishes and the putative orthologs from other teleost fishes (83,88%). Phylogenetic analysis clustered the zebrafish FABP4 with all Antarctic fish H6-FABPs and putative FABP4s from other fishes in a single clade, and then with the mammalian FABP4s in an extended clade. Zebrafish fabp4 was assigned to linkage group 19 at a distinct locus from fabp3. A number of closely linked syntenic genes surrounding the zebrafish fabp4 locus were found to be conserved with human FABP4. The zebrafish fabp4 transcripts showed sequential distribution in the developing eye, diencephalon and brain vascular system, from the middle somitogenesis stage to 48 h postfertilization, whereas fabp3 mRNA was located widely in the embryonic and/or larval central nervous system, retina, myotomes, pancreas and liver from middle somitogenesis to 5 days postfertilization. Differentiation in developmental regulation of zebrafish fabp4 and fabp3 gene transcription suggests distinct functions for these two paralogous genes in vertebrate development. [source] Dynamic expression of Krüppel-like factor 4 (Klf4), a target of transcription factor AP-2, during murine mid-embryogenesisTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 2 2003Julia Ehlermann Abstract Krüppel-like factor 4 (Klf4) belongs to the family of transcription factors that are thought to be involved in the regulation of epithelial and germ cell differentiation, based on their expression in postproliferative cells of the skin, gut, and testes. Gene ablation experiments suggest that Klf4 plays a role in keratinocyte differentiation, since mice lacking Klf4 fail to establish proper barrier function and, as a consequence, die postnatally due to dehydration. Recent studies have shown that Klf4 is also expressed in postnatal male mice, in postmeiotic sperm cells undergoing terminal differentiation into sperm cells. However, prior to the current study, the expression pattern of Klf4 during early and mid-embryogenesis had not been examined. Here we demonstrate that Klf4 transcripts can be detected from embryonic day 4.5 (E4.5) on in the developing conceptus, and that Klf4 expression before E10 is restricted to extraembryonic tissues. The embryo proper displays a highly dynamic and changing Klf4 signal from E10 of murine development on. In addition to being expressed in a stripe of mesenchymal cells extending from the forelimb bud rostrally over the branchial arches to the developing eye, Klf4 is also expressed in the mesenchyme surrounding the nasal pit at day E11.5. In addition, Klf4 has been detected in the apical ectodermal ridge and adjacent mesenchymal cells in the limb buds, and in mesenchymal cells of the developing body wall in trunk areas. These findings suggest that Klf4 plays an important role in regulating cellular proliferation, which underlies the morphogenetic changes that shape the developing embryo. Anat Rec Part A 273A:677,680, 2003. © 2003 Wiley-Liss, Inc. [source] An in ovo chicken model to study the systemic and localized teratogenic effects of valproic acidBIRTH DEFECTS RESEARCH, Issue 4 2002Amy I. Whitsel Background The antiepileptic valproic acid (VPA) is a teratogen whose embryopathic mechanism(s) remain uncertain. Elucidating potential cellular and molecular effects of VPA is complicated by systemic application paradigms. We developed an in ovo model to reproduce the teratogenic effects of VPA and a localized VPA application procedure to determine whether VPA can selectively effect abnormal development in one region of the embryo. Methods VPA was applied topically to chicken embryos in ovo at different embryonic stages. Embryos were later evaluated for gross and skeletal anomalies. Pax-2 and Pax-6 protein expression in the developing eye was also evaluated because VPA-induced eye anomalies are similar to those seen by the disruption of Pax-2 and Pax-6. For localized application, a thin sheet of the synthetic polymer Elvax was impregnated with VPA. A small piece of the VPA-impregnated polymer was applied directly to the presumptive wing bud region in Stage 10,17 embryos. Embryos were examined for gross and skeletal anomalies. Sham controls were employed for all experiments. Results Chicken embryos exposed to VPA in ovo demonstrated increased mortality, growth delay and anomalies similar to ones previously seen in humans: neural tube, cardiovascular, craniofacial, limb and skeletal. Pax-2 and Pax-6 protein expression was qualitatively diminished in the eye. Localized wing bud VPA exposure caused structural abnormalities in the developing wing in the absence of other anomalies in the embryos. These wing defects were similar to those observed after topical whole-embryo VPA application. Conclusions These results indicate that at least one mechanism for the teratogenicity of VPA involves a direct effect on developing tissue. The nature of the abnormalities observed implies that this effect may be mediated by disruption of genes that regulate pattern formation. Teratology 66:153,163, 2002. © 2002 Wiley-Liss, Inc. [source] New blood for hemoglobin in the lens: roles in stem cell differentiation and fibre cell organelle loss?ACTA OPHTHALMOLOGICA, Issue 2008MA WRIDE Purpose Evidence is emerging for haemoglobin (Hb) expression outside the vascular system. We previously demonstrated Hb expression in the mouse lens during post-natal development and cataract progression. Here, we extended this work by carrying out a comprehensive spatio-temporal analysis of Hb subunit expression during mouse lens development and maturation. Methods We used RT-PCR, Western blotting and immunofluorescence to analyze Hb expression in mouse eyes (E16.5 to 9 wks). We also used a sensitive heme assay to test for the presence of heme in the lens by colourimetric assay and histological staining of paraffin-embedded sections. Results Hb subunits were expressed in lens epithelial cells and cortical lens fibre cells. However, the heme assay revealed negligible levels of this prosthetic group in the lens. Hb immunofluorescence was also observed in other regions of the developing eye including the cornea, the retinal ganglion cell layer and the retinal pigment epithelium. Finally, we also observed Hb expression in early embryos by microarray and during differentiation of embryonic stem (ES) cells into embryoid bodies (EBs) in vitro. Conclusion These results suggest a paradigm shift: Hb subunits are expressed in the eye during development and in the adult and, therefore, may have novel roles in ocular development, physiology and pathophysiology. The absence of heme from the lens indicates that at least some of these functions may be independent of oxygen metabolism. The pattern of expression of Hb in lens epithelial cells and cortical lens fibre cells may indicate an involvement for Hb subunits in lens epithelial cell differentiation into lens fibre cells and/or lens fibre cell organelle loss. [source] | ||||||||||