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1.
Opt Express ; 29(6): 9098-9122, 2021 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-33820345

RESUMO

We analytically and numerically investigate surface second-harmonic generation (SHG) from a stack of dielectric layers. We develop a theoretical formalism based on the transfer matrix method for the calculation of the surface-driven second-harmonic radiation from multilayer structures and elaborate it for the case of ultrathin dielectric layers using a power series expansion to derive the effective surface nonlinear tensor for the whole stack. We show that for deeply subwavelength thicknesses of the layers the surface responses from all interfaces can efficiently sum up, leading to largely enhanced efficiency of SHG. As a result, such surface-driven nonlinearity can become comparable to the bulk nonlinearity in noncentrosymmetric semiconductors and can yield high performance for nonlinear nanophotonic applications.

2.
Sci Rep ; 10(1): 10545, 2020 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-32601374

RESUMO

We analyse possibilities to quantitatively evaluate the surface second-order optical nonlinearity in noncentrosymmetric materials based on polarization-resolved analysis of far-field radiation patterns of second-harmonic generation. We analytically demonstrate that for plane-wave illumination the contribution to the second-harmonic signal from the surface of a nonlinear medium exhibits different polarization properties and angular dependencies compared to the contribution from the bulk. In view of this, we optimize the illumination geometry in order to enable the most efficient separation and comparison of both nonlinearities. Furthermore, we consider the illumination of an AlGaAs slab by a tightly-focused linearly-polarized Gaussian beam as an alternative measurement geometry. It is found that the reliable separation of the surface nonlinearity contribution as well as a wide range of detectable values can be achieved with this geometry as well.

3.
Dev Cell ; 1(2): 251-64, 2001 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-11702784

RESUMO

Mutations in the zebrafish knypek locus impair gastrulation movements of convergent extension that narrow embryonic body and elongate it from head to tail. We demonstrate that knypek regulates cellular movements but not cell fate specification. Convergent extension movement defects in knypek are associated with abnormal cell polarity, as mutant cells fail to elongate and align medio-laterally. Positional cloning reveals that knypek encodes a member of the glypican family of heparan sulfate proteoglycans. Double mutant and overexpression analyses show that Knypek potentiates Wnt11 signaling, mediating convergent extension. These studies provide experimental and genetic evidence that glypican Knypek acts during vertebrate gastrulation as a positive modulator of noncanonical Wnt signaling to establish polarized cell behaviors underlying convergent extension movements.


Assuntos
Gástrula/fisiologia , Proteoglicanas de Heparan Sulfato/genética , Proteoglicanas de Heparan Sulfato/fisiologia , Proteínas de Peixe-Zebra , Sequência de Aminoácidos , Animais , Padronização Corporal , Divisão Celular , Clonagem Molecular , Cisteína/química , Relação Dose-Resposta a Droga , Glicoproteínas/metabolismo , Hibridização In Situ , Modelos Genéticos , Dados de Sequência Molecular , Mutação , Fenótipo , Ligação Proteica , Estrutura Terciária de Proteína , RNA/metabolismo , RNA Mensageiro/metabolismo , Homologia de Sequência de Aminoácidos , Transdução de Sinais , Fatores de Tempo , Proteínas Wnt , Peixe-Zebra
4.
Cell Death Differ ; 13(2): 223-35, 2006 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-16096653

RESUMO

Cell culture work has identified the tumor suppressor p53 as a component of the S-phase checkpoint control system, while in vivo studies of this role of p53 in whole-vertebrate systems were limited. Here, we describe zebrafish mutants in the DNA polymerase delta catalytic subunit 1, based on the positional cloning of the flathead (fla) gene. fla mutants display specific defects in late proliferative zones, such as eyes, brain and cartilaginous elements of the visceral head skeleton, where cells display compromised DNA replication, followed by apoptosis, and partial or complete loss of affected tissues. Antisense-mediated knockdown of p53 in fla mutants leads to a striking rescue of all phenotypic traits, including completion of replication, survival of cells, and normal differentiation and tissue formation. This indicates that under replication-compromised conditions, the p53 branch of the S-phase checkpoint is responsible for eliminating stalled cells that, given more time, would have otherwise finished their normal developmental program.


Assuntos
Apoptose , Diferenciação Celular , DNA Polimerase III/metabolismo , Mutação , Proteína Supressora de Tumor p53/fisiologia , Peixe-Zebra/genética , Sequência de Aminoácidos , Animais , Encéfalo/citologia , Encéfalo/embriologia , Proliferação de Células , DNA Polimerase III/deficiência , DNA Polimerase III/genética , Replicação do DNA , Olho/citologia , Olho/embriologia , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Masculino , Dados de Sequência Molecular , Fenótipo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fase S , Crânio/citologia , Crânio/embriologia , Proteína Supressora de Tumor p53/deficiência , Proteína Supressora de Tumor p53/genética , Regulação para Cima/genética , Regulação para Cima/fisiologia , Peixe-Zebra/embriologia , Peixe-Zebra/fisiologia , Zigoto/citologia , Zigoto/enzimologia , Zigoto/fisiologia
5.
Curr Biol ; 4(3): 189-202, 1994 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-7922324

RESUMO

BACKGROUND: In Drosophila melanogaster and Caenorhabditis elegans, the elucidation of developmental mechanisms has relied primarily on the systematic induction and isolation of mutations in genes with specific functions in development. Such an approach has not yet been possible in a vertebrate species, owing to the difficulty of analyzing and keeping a sufficiently high number of mutagenized lines of animals. RESULTS: We have developed the methods necessary to perform large-scale saturation screens for mutations affecting embryogenesis in the zebrafish, Danio (Brachydanio) rerio. Firstly, a new aquarium system was developed to raise and keep large numbers of strains of genetically different fish safely and with little maintenance care. Secondly, by placing adult male fish in water containing the chemical mutagen, ethylnitrosourea, we induced point mutations in premeiotic germ cells with a rate of one to three mutations per locus per 1,000 mutagenized haploid genomes. This rate, which is similar to the mutagenesis rates produced by ethylmethanesulfonate in Drosophila, was determined for alleles at four different pigmentation genes. Finally, in a pilot screen in which mutagenized fish were inbred for two generations and scored for embryonic mutants, we isolated 100 recessive mutations with phenotypes visible in the homozygous embryos. CONCLUSION: The high rate of induction and recovery of point mutations, in addition to an efficient aquarium system to house large numbers of mutagenized lines, means that it is now possible to perform saturation mutagenesis screens in a vertebrate, similar to those done in invertebrates.


Assuntos
Peixe-Zebra/genética , Criação de Animais Domésticos , Animais , Cruzamentos Genéticos , Desenvolvimento Embrionário e Fetal/genética , Metanossulfonato de Etila , Etilnitrosoureia , Feminino , Deleção de Genes , Genes Letais , Masculino , Meiose/genética , Mitose/genética , Mutagênese , Projetos Piloto , Mutação Puntual , Espermatogênese/genética , Peixe-Zebra/embriologia
6.
Trends Genet ; 13(1): 14-21, 1997 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-9009843

RESUMO

Members of the Hedgehog family of signaling molecules mediate many important short- and long-range patterning processes during invertebrate and vertebrate development. In the fly, a single hedgehog gene regulates segmental and imaginal disc patterning. In contrast, in vertebrates a hedgehog gene family is involved in the control of left-right asymmetry, polarity in the central nervous system (CNS), somites and limb, organogenesis, chondrogenesis and spermatogenesis. Here, we review recent experiments addressing the function of the various Hedgehog members during invertebrate and vertebrate development.


Assuntos
Proteínas de Drosophila , Regulação da Expressão Gênica no Desenvolvimento , Proteínas de Insetos/fisiologia , Proteínas/fisiologia , Transativadores , Animais , Drosophila/embriologia , Drosophila/genética , Previsões , Proteínas Hedgehog , Humanos , Proteínas de Insetos/química , Proteínas/química , Transdução de Sinais , Vertebrados/genética
7.
Cell Death Differ ; 12(1): 52-64, 2005 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-15529176

RESUMO

The tumor suppressor p53 has two alternative effects, causing either cell cycle arrest or apoptosis. These different effects are supposed to be mediated by the transcriptional activation of different target genes. perp, encoding a transmembrane protein of the Pmp22 family, is a transcriptional p53 target exclusively upregulated in apoptotic cells. However, its role during normal development had remained largely unclear. Here, we report the isolation and characterization of a zebrafish perp homolog. Upon overexpression in early zebrafish embryos, perp induces apoptosis. In addition, it contributes to p53-dependent and UV-induced cell death. However, during normal zebrafish development, perp displays a p53-independent and spatially restricted expression in specific cell types and tissues. Antisense-mediated loss of Perp function leads to increased apoptosis in perp-expressing cells of the developing skin and notochord. We conclude that, in contrast to its proapoptotic function in stressed cells, Perp plays an antiapoptotic role during normal zebrafish development to regulate tissue-specific cell survival.


Assuntos
Proteínas de Membrana/genética , Proteínas de Peixe-Zebra/genética , Peixe-Zebra/embriologia , Animais , Apoptose/fisiologia , Apoptose/efeitos da radiação , Inibidores de Caspase , Caspases/metabolismo , Sobrevivência Celular/efeitos da radiação , Clonagem Molecular , Embrião não Mamífero/metabolismo , Embrião não Mamífero/efeitos da radiação , Regulação da Expressão Gênica no Desenvolvimento/efeitos da radiação , Proteínas de Membrana/fisiologia , Notocorda/embriologia , Notocorda/metabolismo , Fosfoproteínas/genética , RNA Mensageiro/administração & dosagem , Pele/embriologia , Pele/metabolismo , Transativadores/genética , Fatores de Transcrição/genética , Proteína Supressora de Tumor p53/genética , Raios Ultravioleta , Peixe-Zebra/genética , Proteínas de Peixe-Zebra/fisiologia
8.
Mech Dev ; 108(1-2): 179-84, 2001 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11578872

RESUMO

In this paper we describe the mRNA expression patterns of members of the bone morphogenetic protein (BMP) signalling pathway in the developing zebrafish ear. bmp2b, 4, and 7 are expressed in discrete areas of otic epithelium, some of which correspond to sensory patches. bmp2b and 4 mark the developing cristae before and during the appearance of differentiated hair cells. bmp4 is also expressed in a dorsal, non-sensory region of the ear. Expression of bmps in cristae is conserved between zebrafish, chick, and mouse, but there are also notable differences in ear expression patterns between these species. Of five zebrafish BMP antagonists, only one (follistatin) shows significant expression in the otic epithelium. The type I receptor bmpr-IB shows localised expression in the ear epithelium. Mediators of BMP signalling, smad1 and smad5, are expressed in statoacoustic and lateral line ganglia; smad5 is also expressed at low levels throughout the ear epithelium. An inhibitory smad, smad6, is expressed laterally in the ear epithelium. Lateral line primordia and neuromasts also express bmp2b, 4, follistatin, smad1, and smad5. The conservation of bmp expression in cristae among different species adds weight to the growing evidence that BMPs are required for the development of the vertebrate ear.


Assuntos
Proteínas Morfogenéticas Ósseas/genética , Orelha Interna/embriologia , Peixe-Zebra/embriologia , Peixe-Zebra/genética , Animais , Padronização Corporal/genética , Embrião de Galinha , Regulação da Expressão Gênica no Desenvolvimento , Hibridização In Situ , Camundongos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Transdução de Sinais
9.
Gene ; 246(1-2): 69-80, 2000 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-10767528

RESUMO

smad genes encode transcription factors involved in the signal transduction of members of the TGFbeta superfamily. We report here the cloning, characterization and genomic mapping of smad2, smad3 and smad4 from the zebrafish, Danio rerio. In Xenopus, smad2 overexpression has been shown to interfere with gastrulation and dorsal cell fate specification. However, full-length zebrafish smad2, although functionally active in Xenopus explants, has no effect when overexpressed in zebrafish embryos. In contrast, an N-terminally truncated, constitutively active version of Smad2 protein causes severe dorsalization or partial secondary axis formation, pointing to a role of Smad2 during mesoderm and axis formation. The temporal and spatial expression patterns of zebrafish smad2, 3 and 4 were investigated by developmental RT-PCR and whole mount in-situ hybridization. All three genes show strong and ubiquitous maternal expression. Zygotic expression is weak and ubiquitous in the case of smad2, and strong and ubiquitious in the case of smad4, while smad3 shows a spatially restricted zygotic expression pattern. It is expressed in migrating neural crest cells of the trunk and a subset of cells in the diencephalon in close proximity to the expression domain of the Nodal-related protein Cyclops/Ndr2/Znr1, a potential signal upstream of Smad2/3 required for eye-field separation and floor plate specification. Overexpression of truncated smad2 in cyclops mutant embryos leads to a rescue of the eye and floorplate defects. These data suggest that Smad2 acts as a mediator of Nodal signals during zebrafish midline signaling, while Smad3 might be involved in later steps of eye field separation.


Assuntos
Proteínas de Ligação a DNA/genética , Transativadores/genética , Proteínas de Xenopus , Proteínas de Peixe-Zebra , Peixe-Zebra/genética , Sequência de Aminoácidos , Animais , Mapeamento Cromossômico , Clonagem Molecular , Embrião não Mamífero/metabolismo , Desenvolvimento Embrionário , Regulação da Expressão Gênica no Desenvolvimento , Peptídeos e Proteínas de Sinalização Intracelular , Dados de Sequência Molecular , Mutação , Fatores de Crescimento Neural , RNA Mensageiro/administração & dosagem , RNA Mensageiro/genética , Homologia de Sequência de Aminoácidos , Proteínas Smad , Proteína Smad2 , Proteína Smad3 , Proteína Smad4 , Fator de Crescimento Transformador beta/genética , Xenopus/genética , Peixe-Zebra/embriologia
10.
Sci Rep ; 4: 5886, 2014 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-25073935

RESUMO

Crystalline silicon photonic crystal slabs are widely used in various photonics applications. So far, the commercial success of such structures is still limited owing to the lack of cost-effective fabrication processes enabling large nanopatterned areas (≫ 1 cm(2)). We present a simple method for producing crystalline silicon nanohole arrays of up to 5 × 5 cm(2) size with lattice pitches between 600 and 1000 nm on glass and flexible plastic substrates. Exclusively up-scalable, fast fabrication processes are applied such as nanoimprint-lithography and silicon evaporation. The broadband light trapping efficiency of the arrays is among the best values reported for large-area experimental crystalline silicon nanostructures. Further, measured photonic crystal resonance modes are in good accordance with light scattering simulations predicting strong near-field intensity enhancements greater than 500. Hence, the large-area silicon nanohole arrays might become a promising platform for ultrathin solar cells on lightweight substrates, high-sensitive optical biosensors, and nonlinear optics.

13.
Development ; 119(4): 1107-18, 1993 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-8306877

RESUMO

Snail, a zinc finger protein, is required for the formation of the ventral furrow and the mesoderm during gastrulation of the Drosophila embryo. snail homologues have been cloned from Xenopus and mouse. We have isolated a zebrafish homologue of snail, designated sna-1. Like its Drosophila counterpart, Sna-1 protein is nuclear. Maternal and zygotic sna-1 transcripts are ubiquitously distributed in zebrafish embryos of cleavage and blastula stages. In gastrulating embryos, sna-1 is expressed in involuting cells of the germ ring, but not in those at the dorsal midline, the presumptive notochordal region. After involution, the expression is maintained in the paraxial mesoderm and becomes prominent in the muscle pioneer precursors, followed by expression at the posterior somite boundaries. Later, sna-1 is expressed in neural crest and mesodermal derivatives of the head region. Sna-1 expression is induced in animal cap cells by activin A. The early sna-1 expression pattern in gastrulating zebrafish no tail (ntl) mutant embryos is normal except a reduction in the level of sna-1 transcription, suggesting that Ntl protein is not the key activator of sna-1 transcription in vivo, but might be involved in the enhancement or maintenance of sna-1 transcription. Data obtained in studies with ectopic ntl expression support this model.


Assuntos
Sequência Conservada , Gástrula/fisiologia , Expressão Gênica/fisiologia , Genes/genética , Peixe-Zebra/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Western Blotting , Drosophila/genética , Mesoderma/fisiologia , Dados de Sequência Molecular , Crista Neural/fisiologia , Peixe-Zebra/embriologia
14.
Dev Biol ; 194(2): 166-71, 1998 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-9501021

RESUMO

Recent results have indicated that cAMP-dependent protein kinase (PKA) acts as a negative regulator of Hedgehog signaling in target cells of the vertebrate embryo. Consequently, suppression of PKA activity is sufficient to mimic the effect of receiving a Hedgehog signal. We have explored whether PKA-inhibiting Gi-proteins (GiPs) may also be involved in the regulation of Hedgehog signaling. Zebrafish embryos were injected with RNA encoding pertussis toxin (Ptx), a specific inhibitor of GiPs. These embryos developed phenotypic traits opposite to embryos expressing a dominant negative form of the PKA regulatory subunit (dnPKA), including a fusion of the eyes, a lack of ventral specification in the forebrain, and an expansion of the sclerotome at the expense of adaxial fates in the posterior somites. These effects can be partially rescued by coexpression of dnPKA, but not by coexpression of Indian Hedgehog, suggesting that GiPs act upstream of PKA and downstream of Hedgehogs. Other Hedgehog- and PKA-dependent processes, sclerotomal specification and adaxial specification in the first five somites, are not negatively affected by Ptx. Thus, GiPs may be involved in Hedgehog signaling in some, but not all target cells.


Assuntos
Indução Embrionária , Subunidades alfa Gi-Go de Proteínas de Ligação ao GTP/fisiologia , Toxina Pertussis , Proteínas/fisiologia , Transdução de Sinais , Transativadores , Fatores de Virulência de Bordetella/metabolismo , Peixe-Zebra/embriologia , Animais , Padronização Corporal , Encéfalo/embriologia , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Dimerização , Olho/embriologia , Técnicas de Transferência de Genes , Proteínas Hedgehog , Ligantes , RNA/metabolismo , Receptores de Superfície Celular/metabolismo , Fatores de Virulência de Bordetella/genética
15.
Dev Dyn ; 216(3): 285-98, 1999 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-10590480

RESUMO

Smad1 and smad5 encode transcription factors that have been implicated in the transduction of signaling by the bone morphogenetic proteins Bmp2 and/or Bmp4. Here we report the characterization of Smad1 and Smad5 from the zebrafish, Danio rerio. Although smad1, smad5, bmp2b, and bmp4 are all expressed during gastrulation and although all four proteins have ventralizing activities, they appear to play distinct roles during dorsoventral pattern formation. smad1 expression starts shortly before the onset of gastrulation. It is expressed on the ventral side of the embryo, whereas smad5 transcripts are both maternally and zygotically provided and ubiquitously distributed. Injection studies and mutant analyses suggest that the ventral smad1 expression is positively regulated by Bmp2b, but not by Bmp4 signaling, whereas smad5 expression is independent of Bmp2b. Also, the dorsalized phenotype of bmp2b-mutant embryos can be rescued by exogenous Smad1, but not by Smad5. Together, these data suggest that smad1 acts later than smad5 and is itself a transcriptional target of Smad5-mediated Bmp2b signaling. During later stages of development, smad1 is expressed in eyes, dorsal cells of rhombomeres 1, 3, and 5, and somites, with highest mRNA levels in the presumptive sclerotome and adaxial regions near the notochord. Injection experiments indicate that this somitic smad1 expression is positively regulated by hedgehog signaling from the dorsal midline, thus perhaps accounting for the recently reported sonic hedgehog-induced competence of sclerotomal cells to Bmp2/4 signals.


Assuntos
Padronização Corporal/fisiologia , Proteínas de Ligação a DNA/metabolismo , Proteínas de Drosophila , Fosfoproteínas/metabolismo , Transativadores/metabolismo , Peixe-Zebra/embriologia , Animais , Proteína Morfogenética Óssea 2 , Proteína Morfogenética Óssea 4 , Proteínas Morfogenéticas Ósseas/genética , Proteínas Morfogenéticas Ósseas/metabolismo , Clonagem Molecular , DNA Complementar/metabolismo , Olho/embriologia , Olho/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Proteínas Hedgehog , Hibridização In Situ , Proteínas de Insetos/metabolismo , Mutação , Fenótipo , Filogenia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transdução de Sinais/fisiologia , Proteínas Smad , Proteína Smad5 , Fatores de Tempo , Distribuição Tecidual , Fator de Crescimento Transformador beta/metabolismo , Proteínas de Peixe-Zebra
16.
Dev Dyn ; 222(4): 681-7, 2001 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-11748836

RESUMO

Bone morphogenetic proteins (Bmps) and their roles during early dorsoventral patterning of the vertebrate embryo are well understood. The role and regulation of a more distant member of this family, the anti-dorsalizing morphogenetic protein (Admp), however, are less clear. Here, we report the isolation and characterization of zebrafish admp. Unlike other bmps, admp is exclusively expressed on the dorsal side. Expression starts at blastula stages in the region of the organizer, giving rise to anterior neuroectoderm and axial mesoderm. During the course of gastrulation, both the neuroectodermal and the mesodermal admp transcripts vanish in an anterior-posterior wave. The maintenance of admp expression is positively influenced by Nodal signaling and by Bozozok (Boz), an organizer-promoting homeodomain protein acting as a repressor of early bmp2b expression. Despite the positive effect of boz on admp expression, Boz and Admp have rather opposite effects on zebrafish patterning, as revealed in gain- and loss-of-function experiments. Upon overexpression, admp has Bmp-like activities causing a smaller organizer and enhanced ventral specification, very similar to the phenotype caused by the loss of boz function in mutant embryos. Antisense-based admp knockdown, on the other side, leads to an enlarged organizer and impaired ventral and posterior development, as observed in embryos after boz overexpression. This finding indicates that admp is required for the development of embryonic structures normally suppressed by organizer activities. The seeming discrepancy between the regulative and functional relationship of boz and admp is discussed, and models are proposed according to which Admp might be part of a negative feedback loop to pattern and confine the organizer region.


Assuntos
Proteínas Morfogenéticas Ósseas/fisiologia , Organizadores Embrionários/fisiologia , Proteínas de Peixe-Zebra , Peixe-Zebra/embriologia , Animais , Blastocisto/fisiologia , Padronização Corporal/fisiologia , Proteínas Morfogenéticas Ósseas/isolamento & purificação , Proteínas Morfogenéticas Ósseas/metabolismo , Embrião não Mamífero/fisiologia , Gástrula/fisiologia , Proteínas de Homeodomínio/fisiologia , Mesoderma/fisiologia , Sistema Nervoso/embriologia , Proteína Nodal , Transdução de Sinais/fisiologia , Distribuição Tecidual , Fator de Crescimento Transformador beta/fisiologia
17.
Genes Dev ; 13(16): 2072-86, 1999 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-10465785

RESUMO

The mechanisms that control cell proliferation and cell differentiation during morphogenesis of the endochondral skeleton of vertebrates are poorly understood. Indian hedgehog (Ihh) signaling from prehypertrophic chondrocytes has been implicated in the control of chondrocyte maturation by way of feedback control of a second secreted factor parathyroid hormone-related peptide (PTHrP) at the articular surfaces. Analysis of an Ihh null mutant suggests a more extensive role for Ihh in skeletal development. Mutants display markedly reduced chondrocyte proliferation, maturation of chondrocytes at inappropriate position, and a failure of osteoblast development in endochondral bones. Together, the results suggest a model in which Ihh coordinates diverse aspects of skeletal morphogenesis through PTHrP-dependent and independent processes.


Assuntos
Condrócitos/citologia , Osteogênese/fisiologia , Proteínas/metabolismo , Transdução de Sinais , Transativadores , Alelos , Animais , Cartilagem/citologia , Diferenciação Celular , Divisão Celular , Deleção de Genes , Proteínas Hedgehog , Camundongos , Camundongos Endogâmicos C57BL , Osteoblastos/fisiologia , Proteínas/genética
18.
Genes Dev ; 10(19): 2452-61, 1996 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-8843197

RESUMO

According to a model based on embryological studies in amphibia, dorsoventral patterning is regulated by the antagonizing function of ventralizing bone morphogenetic proteins (BMPs) and dorsalizing signals generated by Spemann's organizer. Large-scale mutant screens in the zebrafish, Danio rerio, have led to the isolation of two classes of recessive lethal mutations affecting early dorsoventral pattern formation. dino mutant embryos are ventralized, whereas swirl mutants are dorsalized. We show that at early gastrula stages, dino and swirl mutants display an expanded or reduced Bmp4 expression, respectively. The dino and swirl mutant phenotypes both can be phenocopied and rescued by the modulation of BMP signaling in wild-type and mutant embryos. By suppressing BMP signaling in dino mutants, adult fertile dino -/- fish were generated. These findings, together with results from the analysis of dino-swirl double mutants, indicate that dino fulfills its dorsalizing activity via a suppression of swirl-dependent, BMP-like ventralizing activities. Finally, cell transplantation experiments show that dino is required on the dorsal side of early gastrula embryos and acts in a non-cell-autonomous fashion. Together, these results provide genetic evidence in support of a mechanism of early dorsoventral patterning that is conserved among vertebrate and invertebrate embryos.


Assuntos
Padronização Corporal , Proteínas Morfogenéticas Ósseas/fisiologia , Mutação/fisiologia , Receptores de Fatores de Crescimento , Peixe-Zebra/embriologia , Animais , Receptores de Proteínas Morfogenéticas Ósseas , Proteínas Morfogenéticas Ósseas/análise , Proteínas Morfogenéticas Ósseas/genética , Proteínas de Transporte , Transplante de Células , Quimera , Ectoderma , Embrião não Mamífero/química , Embrião não Mamífero/citologia , Desenvolvimento Embrionário , Epistasia Genética , Gástrula , Expressão Gênica , Mesoderma , Fenótipo , Proteínas/fisiologia , RNA Mensageiro , Receptores de Superfície Celular/fisiologia , Transdução de Sinais , Peixe-Zebra/genética
19.
Genes Dev ; 10(6): 647-58, 1996 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-8598293

RESUMO

Midline signaling by Hedgehog (Hh) family members has been implicated in patterning the vertebrate embryo. We have explored the potential regulatory role of cAMP-dependent protein kinase A (PKA) in these events. Zebrafish embryos injected with RNAs encoding Sonic hedgehog (Shh), Indian hedgehog (Ihh), or a dominant-negative regulatory subunit of PKA, PKI, have equivalent phenotypes. These include the expansion of proximal fates in the eye, ventral fates in the brain, and adaxial fates in somites and head mesenchyme. Moreover, ectopic expression of PKI partially rescues somite and optic stalk defects in no tail and cyclops mutants that lack midline structures that normally synthesize Shh. Conversely, all cell types promoted by ectopic expression of hhs and PKI are suppressed in embryos injected with RNA encoding a constitutively active catalytic subunit of PKA (PKA*). These results, together with epistasis studies on the block of ectopic Hh signaling by PKA*, indicate that PKA acts in target cells as a common negative regulator of Hedgehog signaling.


Assuntos
Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Desenvolvimento Embrionário , Indução Embrionária , Proteínas/metabolismo , Transdução de Sinais , Transativadores , Animais , Sistema Nervoso Central/embriologia , Clonagem Molecular , Proteínas Quinases Dependentes de AMP Cíclico/antagonistas & inibidores , Proteínas Quinases Dependentes de AMP Cíclico/genética , Epistasia Genética , Olho/embriologia , Regulação da Expressão Gênica no Desenvolvimento , Técnicas de Transferência de Genes , Proteínas Hedgehog , Mutação/genética , Fenótipo , Proteínas/genética , RNA/genética , RNA/metabolismo , Peixe-Zebra/embriologia
20.
Development ; 124(22): 4457-66, 1997 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-9409664

RESUMO

Early dorsoventral pattern formation in vertebrate embryos is regulated by opposing activities of ventralizing bone morphogenetic proteins (BMPs) and dorsal-specific BMP antagonists such as Chordin, Noggin and Follistatin. Specific defects in early dorsoventral patterning have been recently found in a number of zebrafish mutants, which exhibit either a ventralized or dorsalized phenotype. One of these, the ventralized mutant chordino (originally called dino) is caused by a mutation in the zebrafish chordin homologue and interacts genetically with the dorsalized mutant swirl. In swirl mutant embryos, dorsal structures such as notochord and somites are expanded while ventral structures such as blood and nephros are missing. Here we demonstrate that the swirl phenotype is caused by mutations in the zebrafish bmp2 gene (zbmp2). While injection of mRNAs encoded by the mutant alleles has no ventralizing effect, injection of wild-type zbmp2 mRNA leads to a complete rescue of the swirl mutant phenotype. Fertile adult mutant fish were obtained, showing that development after gastrulation is not dependent on zbmp2 function. In addition zBMP2 has no maternal role in mesoderm induction. Our analysis shows that swirl/BMP2, unlike mouse BMP2 but like mouse BMP4, is required for early dorsoventral patterning of the zebrafish embryo.


Assuntos
Proteínas Morfogenéticas Ósseas/genética , Peptídeos e Proteínas de Sinalização Intercelular , Mutação , Fator de Crescimento Transformador beta , Peixe-Zebra/embriologia , Peixe-Zebra/genética , Alelos , Animais , Proteína Morfogenética Óssea 2 , Proteína Morfogenética Óssea 4 , Proteínas Morfogenéticas Ósseas/metabolismo , Primers do DNA/genética , Feminino , Ligação Genética , Glicoproteínas/genética , Coração/embriologia , Hematopoese/genética , Masculino , Mesoderma/citologia , Camundongos , Camundongos Knockout , Fenótipo , RNA Mensageiro/genética , Peixe-Zebra/metabolismo , Proteínas de Peixe-Zebra
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