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Mechanisms of Development Aug 2007Cilia play key roles in many aspects of embryogenesis and adult physiology in vertebrates. Past genetic screens in zebrafish identified numerous defects of ciliogenesis,...
Cilia play key roles in many aspects of embryogenesis and adult physiology in vertebrates. Past genetic screens in zebrafish identified numerous defects of ciliogenesis, including several mutations in the components of the intraflagellar transport machinery. In contrast to previous studies, here we describe a collection of mutants that affect subpopulations of cilia. Mutant embryos are characterized by a shortening and an abnormal movement of kidney cilia, and in one case also a reduction of cilia length in the Kupffer's vesicle. In contrast to that, the cilia of sensory neurons, including photoreceptor cells, hair cells, and olfactory sensory cells, appear grossly intact. Motility defects of pronephric cilia vary in mutant strains from complete paralysis to an increased frequency of movement, and are associated with left-right asymmetry defects. While ciliary ultrastructure is normal in most mutants, one of the mutant loci is essential for the formation of proper microtubule architecture in the axoneme of pronephric cilia. Mutants characterized in this study reveal intriguing genetic differences between subpopulations of embryonic cilia, and provide an opportunity to study several aspects of cilia structure and function.
Topics: Animals; Body Patterning; Cilia; Mutation; Nephrons; Zebrafish; Zebrafish Proteins
PubMed: 17576052
DOI: 10.1016/j.mod.2007.04.004 -
Developmental Biology Sep 1993Cell migration and cell-cell interactions play important roles in numerous processes during embryogenesis. One of these is the formation of the pronephric (Wolffian)...
Cell migration and cell-cell interactions play important roles in numerous processes during embryogenesis. One of these is the formation of the pronephric (Wolffian) duct (PD), which connects the pronephros to the cloaca. It is currently accepted that in most amphibians the pronephric duct is formed by active migration of the pronephric duct rudiment (PDR) cells along a predetermined pathway. However, there is evidence that in Xenopus, the PD may be formed entirely by in situ segregation of cells out of the lateral mesoderm. In this study, we show, using PDR ablation and Xenopus laevis-Xenopus borealis chimeras, that PD elongation in Xenopus requires both active cell migration and an induced recruitment of cells from the posterior. We also show that PDR cell migration is limited to only a few stages during development and that this temporal control is due, at least in part, to changes in the competence of the PD pathway to support cell migration.
Topics: Animals; Cell Communication; Cell Differentiation; Cell Movement; Chimera; Cloaca; Humans; Time Factors; Wolffian Ducts; Xenopus; Xenopus laevis
PubMed: 8365571
DOI: 10.1006/dbio.1993.1245 -
Developmental Biology Jan 2022The corpuscles of Stannius (CS) represent a unique endocrine organ of teleostean fish that secrets stanniocalcin-1 (Stc1) to maintain calcium homeostasis. Appearing at...
The corpuscles of Stannius (CS) represent a unique endocrine organ of teleostean fish that secrets stanniocalcin-1 (Stc1) to maintain calcium homeostasis. Appearing at 20-25 somite stage in the distal zebrafish pronephros, stc1-expressing cells undergo apical constriction, and are subsequently extruded to form a distinct gland on top of the distal pronephric tubules at 50 h post fertilization (hpf). Several transcription factors (e.g. Hnf1b, Irx3b, Tbx2a/b) and signaling pathways (e.g. Notch) control CS development. We report now that Fgf signaling is required to commit tubular epithelial cells to differentiate into stc1-expressing CS cells. Inhibition of Fgf signaling by SU5402, dominant-negative Fgfr1, or depletion of fgf8a prevented CS formation and stc1 expression. Ablation experiments revealed that CS have the ability to partially regenerate via active cell migration involving extensive filopodia and lamellipodia formation. Activation of Wnt signaling curtailed stc1 expression, but had no effect on CS formation. Thus, our observations identify Fgf signaling as a crucial component of CS cell fate commitment.
Topics: Animals; Cell Differentiation; Endocrine Glands; Fibroblast Growth Factors; Glycoproteins; Pronephros; Wnt Signaling Pathway; Zebrafish; Zebrafish Proteins
PubMed: 34666023
DOI: 10.1016/j.ydbio.2021.10.005 -
Development, Growth & Differentiation Dec 1996The kidney has been used as a model organ to analyze organogenesis. In in vitro experiments using Xenopus blastula ectoderm, the development of pronephric tubules (the...
The kidney has been used as a model organ to analyze organogenesis. In in vitro experiments using Xenopus blastula ectoderm, the development of pronephric tubules (the prototype of the kidney) may be induced by treatment with activin A and retinoic acid (RA). The present study examined whether pronephric tubules induced in ectodermal explants exhibited similar characteristics to those of normal embryos at the molecular level. The experimental conditions required for high frequency induction (100%) of pronephric tubule formation from presumptive ectoderm without the development of muscle and notochord were determined. The developmental expression of the pronephros marker genes Xlim-1 and Xlcaax-1 was examined in induced pronephric tubules. After treatment with 10 ng/mL activin A and 10 mol/L RA, only pronephric tubules were induced at a high frequency. Induced pronephric tubules showed the same timing and patterns of expression for the marker genes Xlim-1 and Xlcaax-1 as normal embryos. These results suggest that the in vitro development of pronephric tubules induced in the presumptive ectoderm by activin A and RA parallels normal development at the molecular level.
PubMed: 37281281
DOI: 10.1046/j.1440-169X.1996.t01-5-00006.x -
Differentiation; Research in Biological... Sep 2001The osmoregulatory function of the pronephric kidney, the first excretory organ of the vertebrate embryo, is essential for embryonic survival. The transport systems...
The osmoregulatory function of the pronephric kidney, the first excretory organ of the vertebrate embryo, is essential for embryonic survival. The transport systems engaged in pronephric osmotic regulation are however poorly understood. The Na,K-ATPase is the key component in renal solute transport and water homeostasis. In the present study, we characterized the alpha, beta, and gamma subunits of the Na,K-ATPase of the developing Xenopus embryo. In addition to the known alpha1, beta1, beta3 and gamma subunits, we report here the identification of a novel cDNA encoding the Xenopus beta2 subunit. We demonstrate by in situ hybridization that each Xenopus Na,K-ATPase subunit exhibits a distinct tissue-specific and developmentally regulated expression pattern. We found that the developing pronephric kidney expresses alpha1, beta1, and gamma subunits uniformly along the entire length of the nephron. Onset of pronephric Na,K-ATPase subunit expression occurred in a coordinated fashion indicating that a common regulatory mechanism may initiate pronephric transcription of these genes. The ability to engage in active Na+ reabsorption appears to be established early in pronephric development, since Na,K-ATPase expression was detected well before the completion of pronephric organogenesis. Furthermore, Na,K-ATPase expression defines at the molecular level the onset of maturation phase during pronephric kidney organogenesis. Taken together, our studies reveal a striking conservation of Na,K-ATPase subunit expression between pronephric and metanephric kidneys. The pronephric kidney may therefore represent a simplified model to dissect the regulatory mechanisms underlying renal Na,K-ATPase subunit expression.
Topics: Amino Acid Sequence; Animals; Cloning, Molecular; Embryo, Nonmammalian; Gene Expression Regulation, Developmental; Kidney; Molecular Sequence Data; Organ Specificity; Phylogeny; Sequence Homology, Amino Acid; Sodium-Potassium-Exchanging ATPase; Xenopus Proteins; Xenopus laevis; Zebrafish Proteins
PubMed: 11686233
DOI: 10.1046/j.1432-0436.2001.680205.x -
Journal of Anatomy Oct 1938
PubMed: 17104742
DOI: No ID Found -
Journal of Anatomy Jan 1944
PubMed: 17104942
DOI: No ID Found -
The International Journal of... 2018LRPAP1, also known as receptor associated protein (RAP) is a small protein of 40 kDa associated with six of the seven members of the evolutionary conserved family of LDL...
LRPAP1, also known as receptor associated protein (RAP) is a small protein of 40 kDa associated with six of the seven members of the evolutionary conserved family of LDL receptors. Numerous studies showed that LRPAP1 has a dual function, initially as a chaperone insuring proper formation of intermolecular disulfide bonds during biogenesis of low density lipoprotein (LDL) receptors and later as an escort protein during trafficking through the endoplasmic reticulum and the early Golgi compartment, preventing premature interaction of receptor and ligand. Because of the general influence of LRPAP1 protein on lipid metabolism, we analyzed the temporal and spatial expression of the Xenopus laevis ortholog of lrpap1. Here, we show that lrpap1 was expressed in the developing neural system, the eye and ear anlagen, the branchial arches, the developing skin and the pronephric kidney. The very high expression level of lrpap1 specifically in the proximal tubules of the developing pronephros establishes this gene as a novel marker for the analysis of pronephros formation.
Topics: Animals; Biomarkers; Embryo, Nonmammalian; Embryonic Development; Gene Expression Regulation, Developmental; Kidney Tubules, Proximal; LDL-Receptor Related Protein-Associated Protein; Organogenesis; Xenopus Proteins; Xenopus laevis
PubMed: 29877571
DOI: 10.1387/ijdb.170295hn -
Developmental Dynamics : An Official... Jul 2005Nephrin (NHPS1) encodes a transmembrane protein of approximately 1,200 amino acids that plays a critical role in podocyte slit-diaphragm formation and the development of...
Nephrin (NHPS1) encodes a transmembrane protein of approximately 1,200 amino acids that plays a critical role in podocyte slit-diaphragm formation and the development of functional mammalian glomerular filtration barriers. In humans and mice with congenital defects in the nephrin gene, the glomerular filtration barrier is defective and protein leakage into the kidney filtrate causes a life-threatening proteinuria. This protein also plays an essential role in the formation of the stellate cells of the Drosophila Malpighian tubules. In this report, the sequence and expression of a Xenopus ortholog of nephrin is described using both conventional and novel three-dimensional (3D) visualization methodologies. Xenopus nephrin encodes a protein of 1,238 amino acids and is expressed at high levels in the forming pronephric kidney glomus, the equivalent of the mammalian glomerulus. Expression commences at stage 25 and is specific to the pronephric glomus up until at least tadpole feeding stages. Two-color fluorescent whole-mount in situ analysis of nephrin expression allowed the 3D shape of the glomus to be imaged and contrasted to the pronephric tubules throughout its morphogenesis. Confocal data processing pipelines were established to generate both volumetric and surface models of the developing pronephros, and a Web-based visualization system was used to generate dynamic and manipulable models of the forming nephric organs. This system allows simple on-line morphometric analysis of the developing pronephric components. As in fish embryos, the glomera first form laterally then migrate medially as the pronephros matures. Unlike in the zebrafish, in Xenopus, this migration stops short of complete fusion of the two glomera at the midline, but a nephrin-positive glomeral nexus does form anteriorly and links the two structures from stage 38 onward.
Topics: Amino Acid Sequence; Animals; DNA, Complementary; Gene Expression Profiling; Gene Expression Regulation, Developmental; Humans; Image Processing, Computer-Assisted; Imaging, Three-Dimensional; Internet; Kidney Glomerulus; Membrane Proteins; Models, Biological; Molecular Sequence Data; Morphogenesis; Sequence Alignment; Sodium-Potassium-Exchanging ATPase; Xenopus laevis
PubMed: 15895368
DOI: 10.1002/dvdy.20415 -
Journal of Cell Science Apr 2014The conserved septin family of filamentous small GTPases plays important roles in mitosis, cell migration and cell morphogenesis by forming scaffolds and diffusion...
The conserved septin family of filamentous small GTPases plays important roles in mitosis, cell migration and cell morphogenesis by forming scaffolds and diffusion barriers. Recent studies in cultured cells in vitro indicate that a septin complex of septin 2, 7 and 9 is required for ciliogenesis and cilia function, but septin function in ciliogenesis in vertebrate organs in vivo is not understood. We show that sept7b is expressed in ciliated cells in different tissues during early zebrafish development. Knockdown of sept7b by using morpholino antisense oligonucleotides caused misorientation of basal bodies and cilia, reduction of apical actin and the shortening of motile cilia in Kupffer's vesicle and pronephric tubules. This resulted in pericardial and yolk sac edema, body axis curvature and hydrocephaly. Notably, in sept7b morphants we detected strong left-right asymmetry defects in the heart and lateral plate mesoderm (situs inversus), reduced fluid flow in the kidney, the formation of kidney cysts and loss of glomerular filtration barrier function. Thus, sept7b is essential during zebrafish development for pronephric function and ciliogenesis, and loss of expression of sept7b results in defects that resemble human ciliopathies.
Topics: Animals; Animals, Genetically Modified; Brain; Cilia; Embryonic Development; Gene Knockdown Techniques; Pronephros; Septins; Zebrafish; Zebrafish Proteins
PubMed: 24496452
DOI: 10.1242/jcs.138495