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Embryonic Patterning (embryonic + patterning)
Selected AbstractsCongenic method in the chick limb buds by electroporationDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 6 2008Takayuki Suzuki Electroporation is a powerful tool with which to study limb development. Limb development, however, remains an intricate series of events, requiring the precise dissection of developmental processes using relevant transgenes. In this review, we describe the anatomy of the limb field as the basis of targeted electroporation, and specific expression vectors are discussed. We share a useful protocol for electroporation of chick limb buds, and the expression pattern of enhanced green fluorescent protein in the limb buds is used to demonstrate relevant embryonic patterning. Finally, useful trouble-shooting techniques are described. [source] Sharp developmental thresholds defined through bistability by antagonistic gradients of retinoic acid and FGF signalingDEVELOPMENTAL DYNAMICS, Issue 6 2007Albert Goldbeter Abstract The establishment of thresholds along morphogen gradients in the embryo is poorly understood. Using mathematical modeling, we show that mutually inhibitory gradients can generate and position sharp morphogen thresholds in the embryonic space. Taking vertebrate segmentation as a paradigm, we demonstrate that the antagonistic gradients of retinoic acid (RA) and Fibroblast Growth Factor (FGF) along the presomitic mesoderm (PSM) may lead to the coexistence of two stable steady states. Here, we propose that this bistability is associated with abrupt switches in the levels of FGF and RA signaling, which permit the synchronized activation of segmentation genes, such as mesp2, in successive cohorts of PSM cells in response to the segmentation clock, thereby defining the future segments. Bistability resulting from mutual inhibition of RA and FGF provides a molecular mechanism for the all-or-none transitions assumed in the "clock and wavefront" somitogenesis model. Given that mutually antagonistic signaling gradients are common in development, such bistable switches could represent an important principle underlying embryonic patterning. Developmental Dynamics 236:1495,1508, 2007. © 2007 Wiley-Liss, Inc. [source] Mice with mutations in Mahogunin ring finger-1 (Mgrn1) exhibit abnormal patterning of the left,right axisDEVELOPMENTAL DYNAMICS, Issue 12 2006Christina D. Cota Abstract Mahogunin Ring Finger 1 (Mgrn1) encodes a RING-containing protein with ubiquitin ligase activity that has been implicated in pigment-type switching. In addition to having dark fur, mice lacking MGRN1 develop adult-onset spongy degeneration of the central nervous system and have reduced embryonic viability. Observation of complete situs inversus in a small proportion of adult Mgrn1 mutant mice suggested that embryonic lethality resulted from congenital heart defects due to defective establishment and/or maintenance of the left,right (LR) axis. Here we report that Mgrn1 is expressed in a pattern consistent with a role in LR patterning during early development and that many Mgrn1 mutant embryos show abnormal expression of asymmetrically expressed genes involved in LR patterning. A range of complex heart defects was observed in 20,25% of mid-to-late gestation Mgrn1 mutant embryos and another 20% were dead. This finding was consistent with 46,60% mortality of mutants by weaning age. Our results indicate that Mgrn1 acts early in the LR signaling cascade and is likely to provide new insight into this developmental process as Nodal expression was uncoupled from expression of other Nodal-responsive genes in Mgrn1 mutant embryos. Our work identifies a novel role for MGRN1 in embryonic patterning and suggests that the ubiquitination of MGRN1 target genes is essential for the proper establishment and/or maintenance of the LR axis. Developmental Dynamics 235:3438,3447, 2006. © 2006 Wiley-Liss, Inc. [source] Proprotein convertase genes in Xenopus developmentDEVELOPMENTAL DYNAMICS, Issue 3 2005Sylvia Nelsen Abstract Proprotein convertases (PCs) are a family of serine endoproteases that proteolytically activate many precursor proteins within various secretory pathway compartments. Loss-of-function studies have demonstrated a critical role for these proteases in embryonic patterning and adult homeostasis, yet little is known about how substrate selectivity is achieved. We have identified Xenopus orthologs of three PCs: furin, PC6, and PC4. In addition to previously described isoforms of PC6 and furin, four novel splice isoforms of PC6, which are predicted to encode constitutively secreted proteases, and a putative transmembrane isoform of PC4 were identified. Furin and PC6 are expressed in dynamic, tissue-specific patterns throughout embryogenesis, whereas PC4 transcripts are restricted primarily to germ cells and brain in adult frogs. Developmental Dynamics 233:1038,1044, 2005. © 2005 Wiley-Liss, Inc. [source] Roles of nodal-lefty regulatory loops in embryonic patterning of vertebratesGENES TO CELLS, Issue 11 2001Hou Juan Nodal is a signalling molecule that belongs to the transforming growth factor,, superfamily of proteins, and Lefty proteins are antagonists of Nodal signalling. The nodal and lefty genes form positive and negative regulatory loops that resemble the reaction-diffusion system. As a pair, these genes control various events of vertebrate embryonic patterning, including left-right specification and mesoderm formation. In this review, we will focus on recent studies that have addressed the roles of nodal and lefty in mouse development. [source] Bone morphogenetic proteins in tissue engineering: the road from laboratory to clinic, part II (BMP delivery)JOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, Issue 2-3 2008P. C. Bessa Abstract Bone morphogenetic proteins (BMPs) are cytokines with a strong effect on bone and cartilage growth and with important roles during embryonic patterning and early skeletal formation. BMPs have promising potential for clinical bone and cartilage repair, working as powerful bone-inducing components in diverse tissue-engineering products. Synthetic polymers, natural origin polymers, inorganic materials and composites may be used as carriers for the delivery of BMPs. Carriers range from nanoparticles to complex three-dimensional (3D) scaffolds, membranes for tissue-guided regeneration, biomimetic surfaces and smart thermosensitive hydrogels. Current clinical uses include spinal fusion, healing of long bone defects and craniofacial and periodontal applications, amongst others. BMP-2 and BMP-7 have recently received approval by the US Food and Drug Administration (FDA) for specific clinical cases, delivered in absorbable collagen sponges. Considering the expanding number of publications in the field of BMPs, there are prospects of a brilliant future in the field of regenerative medicine of bone and cartilage with the use of BMPs. Copyright © 2008 John Wiley & Sons, Ltd. [source] The Nature of Exocytosis in the Yolk Trophoblastic Layer of Silver Arowana (Osteoglossum bicirrhosum) Juvenile, the Representative of Ancient Teleost FishesTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 11 2009Marta Jaroszewska Abstract We have chosen the silver arowana (Osteoglossum bicirrhosum), a representative of the most ancient teleost family Osteoglossidae, to address the question of yolk nutrients utilization. Silver arowana have particularly large eggs (1,1.5 cm of diameter) and a unique morphology of the yolk. We present evidence that the yolk cytoplasmic zone (ycz) in the "yolksac juveniles" is a very complex structure involved in sequential processes of yolk hydrolysis, lipoprotein particles synthesis, their transport, and exocytosis. Vacuoles filled with yolk granules in different stages of digestion move from the vitellolysis zone through the ycz to be emptied into the microvillar interspace in the process of exocytosis. The area of the ycz with the abundance of the mitochondria must play an important role in providing energy for both the transport of vacuoles and the release of their contents. Therefore, we postulate that the function of yolk syncytial layer (ysl) as the "early embryonic patterning center" transforms in fish larvae or yolksac juveniles into a predominantly specialized role as the yolk trophoblastic layer (ytl) involved in yolk nutrients utilization. In addition to discovering the mechanism of transformation of the ysl function into ytl function, we suggest that the machinery involved in nutrient mobilization and exocytosis in yolk of arowana yolksac juveniles can be very attractive system for studies of regulatory processes in almost all secretory pathways in animal cells. Anat Rec, 2009. © 2009 Wiley-Liss, Inc. [source] Tumor formation by genetic mutations in the components of the Wnt signaling pathwayCANCER SCIENCE, Issue 3 2003Akira Kikuchi The genetics of development and cancer have converged in the identification of intra- and extra-cellular signaling pathways that are aberrantly regulated in cancer, and are also central to embryonic patterning. The Wnt signaling pathway has provided an outstanding example of this. The genes for ,-catenin, ARC, and Axin in the Wnt signaling pathway are often mutated in human cancers. In all such cases, the common denominator is the activation of gene transcription by ,-catenin. The resulting gene expression profile should provide a significant clue to the developmental mechanisms of cancers carrying defects in the Wnt signaling pathway. In this review, the functions of ,-catenin, APC and Axin, and the alterations of the three genes in human cancers are described. (Cancer Sci 2003; 94: 225,229) [source] | |||||||||||||