Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 11 de 11
Filter
1.
J Anat ; 199(Pt 1-2): 195-204, 2001.
Article in English | MEDLINE | ID: mdl-11523823

ABSTRACT

Emerging developmental studies contribute to our understanding of vertebrate evolution because changes in the developmental process and the genes responsible for such changes provide a unique way for evaluating the evolution of morphology. Endoskeletal limbs, the locomotor organs that are unique to vertebrates, are a popular model system in the fields of palaeontology and phylogeny because their structure is highly visible and their bony pattern is easily preserved in the fossil records. Similarly, limb development has long served as an excellent model system for studying vertebrate pattern formation. In this review, the evolution of vertebrate limb development is examined in the light of the latest knowledge, viewpoints and hypotheses.


Subject(s)
Avian Proteins , Biological Evolution , Extremities/embryology , Animals , Chick Embryo , Ectoderm/physiology , Fibroblast Growth Factors/genetics , Fishes , Gene Expression , Genes , Humans , Limb Buds , Mesoderm/physiology , Mice , Morphogenesis/physiology , T-Box Domain Proteins
2.
Dev Growth Differ ; 43(2): 165-75, 2001 Apr.
Article in English | MEDLINE | ID: mdl-11284966

ABSTRACT

To clarify the roles of fibroblast growth factors (FGF) in limb cartilage pattern formation, the effects of various FGF on recombinant limbs that were composed of dissociated and reaggregated mesoderm and ectodermal jackets were examined. Fibroblast growth factor-soaked beads were inserted just under the apical ectodermal ridge (AER) of recombinant limbs and the recombinant limbs were grafted and allowed to develop. Control recombinant limbs without FGF beads formed one or two cartilage elements. Recombinants with FGF-4 beads formed up to five cartilage elements, which were aligned along the anteroposterior (AP) axis. Each cartilage element showed digit-like segmentation. In contrast, recombinants with FGF-2 beads showed formation of multiple thick and unsegmented cartilage rods, which elongated inside and outside the AP plane from the distal end of the recombinants. Recombinants with FGF-8 beads formed a truncated cartilage pattern and recombinants with FGF-10 beads formed a cartilage pattern similar to that of the control recombinants. The expression of the Fgf-8, Msx-1 and Hoxa-13 genes in the developing recombinant limbs were examined. FGF-4 induced extension of the length of the Fgf-8-positive epidermis, or AER, along the AP axis 5 days after grafting, at which time the digits are specified. FGF-2 induced expansion of the Msx-1-positive area, first in the proximal direction and then along the dorsoventral axis. The functions of these FGF in recombinant and normal limb patterning are discussed in this paper.


Subject(s)
Extremities/growth & development , Fibroblast Growth Factors/physiology , Recombination, Genetic , Animals , Chick Embryo , Gene Expression Regulation, Developmental/physiology , Homeodomain Proteins/genetics
3.
Dev Biol ; 219(1): 18-29, 2000 Mar 01.
Article in English | MEDLINE | ID: mdl-10677252

ABSTRACT

A young tadpole of an anuran amphibian can completely regenerate an amputated limb, and it exhibits an ontogenetic decline in the ability to regenerate its limbs. However, whether mesenchymal or epidermal tissue is responsible for this decrease of the capacity remains unclear. Moreover, little is known about the molecular interactions between these two tissues during regeneration. The results of this study showed that fgf-10 expression in the limb mesenchymal cells clearly corresponds to the regenerative capacity and that fgf-10 and fgf-8 are synergistically reexpressed in regenerating blastemas. However, neither fgf-10 nor fgf-8 is reexpressed after amputation of a nonregenerative limb. Nevertheless, nonregenerative epidermal tissue can reexpress fgf-8 under the influence of regenerative mesenchyme, as was demonstrated by experiments using a recombinant limb composed of regenerative limb mesenchyme and nonregenerative limb epidermis. Taken together, our data demonstrate that the regenerative capacity depends on mesenchymal tissue and suggest that fgf-10 is likely to be involved in this capacity.


Subject(s)
Fibroblast Growth Factors/genetics , Regeneration/genetics , Xenopus/genetics , Xenopus/physiology , Amino Acid Sequence , Animals , Chimera/genetics , Chimera/physiology , Epidermis/physiology , Extremities/physiology , Fibroblast Growth Factor 10 , Fibroblast Growth Factor 8 , Gene Expression Regulation, Developmental , Humans , In Situ Hybridization , Larva/genetics , Larva/growth & development , Larva/physiology , Mesoderm/physiology , Molecular Sequence Data , Sequence Homology, Amino Acid , Xenopus/growth & development , Xenopus Proteins
5.
Proc Natl Acad Sci U S A ; 96(20): 11376-81, 1999 Sep 28.
Article in English | MEDLINE | ID: mdl-10500184

ABSTRACT

Asymmetric expression of Sonic hedgehog (Shh) in Hensen's node of the chicken embryo plays a key role in the genetic cascade that controls left-right asymmetry, but its involvement in left-right specification in other vertebrates remains unclear. We show that mouse embryos lacking Shh display a variety of laterality defects, including pulmonary left isomerism, alterations of heart looping, and randomization of axial turning. Expression of the left-specific gene Lefty-1 is absent in Shh(-/-) embryos, suggesting that the observed laterality defects could be the result of the lack of Lefty-1. We also demonstrate that retinoic acid (RA) controls Lefty-1 expression in a pathway downstream or parallel to Shh. Further, we provide evidence that RA controls left-right development across vertebrate species. Thus, the roles of Shh and RA in left-right specification indeed are conserved among vertebrates, and the Shh and RA pathways converge in the control of Lefty-1.


Subject(s)
Congenital Abnormalities/etiology , Gene Expression Regulation, Developmental , Proteins/physiology , Trans-Activators , Transforming Growth Factor beta/genetics , Tretinoin/physiology , Animals , Base Sequence , Chick Embryo , Hedgehog Proteins , Left-Right Determination Factors , Mice , Mice, Knockout , Molecular Sequence Data , RNA, Messenger/analysis
6.
Mech Dev ; 87(1-2): 181-4, 1999 Sep.
Article in English | MEDLINE | ID: mdl-10495283

ABSTRACT

In here we report the identification of two new members of the T-box gene family, zf-tbx5 and zf-tbx4, from the Zebrafish, Danio rerio. The amino acid sequences within the T-box domain share high homology with the mouse, chick, and newt orthologs. Whole mount in situ hybridization revealed specific expression of these genes in the eye and Fin buds. zf-tbx5 expression is restricted to the pectoral Fin bud, whilst zf-tbx4 transcripts are confined in the pelvic Fin bud. These results reveal the conserved expression pattern of Tbx5 and Tbx4 during appendage development in all animal species studied to date.


Subject(s)
Animal Structures/metabolism , Avian Proteins , Gene Expression Regulation, Developmental , T-Box Domain Proteins/metabolism , Zebrafish Proteins , Amino Acid Sequence , Animals , Eye/embryology , In Situ Hybridization , Molecular Sequence Data , Phylogeny , Sequence Homology, Amino Acid , T-Box Domain Proteins/genetics , Time Factors , Zebrafish
7.
Dev Biol ; 211(1): 133-43, 1999 Jul 01.
Article in English | MEDLINE | ID: mdl-10373311

ABSTRACT

During vertebrate limb development, the apical ectodermal ridge (AER) plays a vital role in both limb initiation and distal outgrowth of the limb bud. In the early chick embryo the prelimb bud mesoderm induces the AER in the overlying ectoderm. However, the direct inducer of the AER remains unknown. Here we report that FGF7 and FGF10, members of the fibroblast growth factor family, are the best candidates for the direct inducer of the AER. FGF7 induces an ectopic AER in the flank ectoderm of the chick embryo in a different manner from FGF1, -2, and -4 and activates the expression of Fgf8, an AER marker gene, in a cultured flank ectoderm without the mesoderm. Remarkably, FGF7 and FGF10 applied in the back induced an ectopic AER in the dorsal median ectoderm. Our results suggest that FGF7 and FGF10 directly induce the AER in the ectoderm both of the flank and of the dorsal midline and that these two regions have the competence for AER induction. Formation of the AER of the dorsal median ectoderm in the chick embryo is likely to appear as a vestige of the dorsal fin of the ancestors.


Subject(s)
Extremities/embryology , Fibroblast Growth Factors/pharmacology , Growth Substances/pharmacology , Animals , Chick Embryo , Ectoderm/drug effects , Fibroblast Growth Factor 10 , Fibroblast Growth Factor 7 , Fibroblast Growth Factor 8 , Fibroblast Growth Factors/metabolism , Gene Expression Regulation, Developmental/drug effects , In Situ Hybridization , RNA, Messenger/metabolism , Tissue Transplantation
8.
Mech Dev ; 80(2): 219-21, 1999 Feb.
Article in English | MEDLINE | ID: mdl-10072792

ABSTRACT

T-box genes are conserved in all animal species. We have identified two members of the T-box gene family from the zebrafish, Danio rerio. Zf-tbr1 and zf-tbx3 share high amino acid identity with human, murine, chick and Xenopus orthologs and are expressed in specific regions during zebrafish development.


Subject(s)
DNA-Binding Proteins/genetics , Gene Expression Regulation, Developmental , T-Box Domain Proteins , Transcription Factors/genetics , Xenopus Proteins , Zebrafish Proteins , Zebrafish/genetics , Amino Acid Sequence , Animals , DNA-Binding Proteins/biosynthesis , Embryo, Nonmammalian/metabolism , Humans , Mice , Molecular Sequence Data , Organ Specificity , Sequence Alignment , Sequence Homology, Amino Acid , Species Specificity , Transcription Factors/biosynthesis , Xenopus , Zebrafish/embryology
9.
Dev Growth Differ ; 41(6): 645-56, 1999 Dec.
Article in English | MEDLINE | ID: mdl-10646794

ABSTRACT

In vertebrates visceral asymmetry is conserved along the left-right axis within the body. Only a small percentage of randomization (situs ambiguus), or complete reversal (situs inversus) of normal internal organ position and structural asymmetry is found in humans. A breakdown in left-right asymmetry is occasionally associated with severe malformations of the organs, clearly indicating that the regulated asymmetric patterning could have an evolutionary advantage over allowing random placement of visceral organs. Genetic, molecular and cell transplantation experiments in humans, mice, zebrafish, chick and Xenopus have advanced our understanding of how initiation and establishment of left-right asymmetry occurs in the vertebrate embryo. In particular, the chick embryo has served as an extraordinary animal model to manipulate genes, cells and tissues. This chick model system has enabled us to reveal the genetic pathways that occur during left-right development. Indeed, genes with asymmetric expression domains have been identified and well characterized using the chick as a model system. The present review summarizes the molecular and experimental studies employed to gain a better understanding of left-right asymmetry pattern formation from the first split of symmetry in embryos, to the exhibition of asymmetric morphologies in organs.


Subject(s)
Body Patterning/genetics , Viscera/embryology , Animals , Embryo, Nonmammalian , Embryonic and Fetal Development , Gene Expression Regulation, Developmental , Humans , Morphogenesis/genetics , Mutation
10.
Development ; 125(22): 4417-25, 1998 Nov.
Article in English | MEDLINE | ID: mdl-9778501

ABSTRACT

We have determined that Strong's Luxoid (lstJ) [corrected] mice have a 16 bp deletion in the homeobox region of the Alx-4 gene. This deletion, which leads to a frame shift and a truncation of the Alx-4 protein, could cause the polydactyly phenotype observed in lstJ [corrected] mice. We have cloned the chick homologue of Alx-4 and investigated its expression during limb outgrowth. Chick Alx-4 displays an expression pattern complementary to that of shh, a mediator of polarizing activity in the limb bud. Local application of Sonic hedgehog (Shh) and Fibroblast Growth Factor (FGF), in addition to ectodermal apical ridge removal experiments suggest the existence of a negative feedback loop between Alx-4 and Shh during limb outgrowth. Analysis of polydactylous mutants indicate that the interaction between Alx-4 and Shh is independent of Gli3, a negative regulator of Shh in the limb. Our data suggest the existence of a negative feedback loop between Alx-4 and Shh during vertebrate limb outgrowth.


Subject(s)
Body Patterning , Extremities/embryology , Homeodomain Proteins/genetics , Limb Deformities, Congenital , Nerve Tissue Proteins , Repressor Proteins , Trans-Activators , Xenopus Proteins , Amino Acid Sequence , Animals , Chick Embryo , Cloning, Molecular , DNA-Binding Proteins , Extremities/surgery , Feedback , Fibroblast Growth Factors , Hedgehog Proteins , Kruppel-Like Transcription Factors , Mice , Mice, Mutant Strains , Molecular Sequence Data , Polydactyly/genetics , Proteins , Sequence Analysis, DNA , Sequence Deletion , Sequence Homology, Amino Acid , Species Specificity , Tissue Transplantation , Transcription Factors , Zinc Finger Protein Gli3
11.
Nature ; 394(6693): 545-51, 1998 Aug 06.
Article in English | MEDLINE | ID: mdl-9707115

ABSTRACT

The handedness of visceral organs is conserved among vertebrates and is regulated by asymmetric signals relayed by molecules such as Shh, Nodal and activin. The gene Pitx2 is expressed in the left lateral plate mesoderm and, subsequently, in the left heart and gut of mouse, chick and Xenopus embryos. Misexpression of Shh and Nodal induces Pitx2 expression, whereas inhibition of activin signalling blocks it. Misexpression of Pitx2 alters the relative position of organs and the direction of body rotation in chick and Xenopus embryos. Changes in Pitx2 expression are evident in mouse mutants with laterality defects. Thus, Pitx2 seems to serve as a critical downstream transcription target that mediates left-right asymmetry in vertebrates.


Subject(s)
Body Patterning/physiology , Homeodomain Proteins/physiology , Nuclear Proteins , Trans-Activators , Transcription Factors/physiology , Transforming Growth Factor beta , Activin Receptors, Type II , Animals , Chick Embryo , Culture Techniques , Hedgehog Proteins , Mice , Molecular Sequence Data , Nodal Protein , Paired Box Transcription Factors , Proteins/physiology , Receptors, Growth Factor/physiology , Situs Inversus/embryology , Xenopus , Homeobox Protein PITX2
SELECTION OF CITATIONS
SEARCH DETAIL
...