The Experts below are selected from a list of 14925 Experts worldwide ranked by ideXlab platform
Carlos F Ibanez - One of the best experts on this subject based on the ideXlab platform.
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growth differentiation factor 11 signals through the transforming growth factor β receptor alk5 to regionalize the Anterior Posterior Axis
EMBO Reports, 2006Co-Authors: Olov Andersson, Eva Reissmann, Carlos F IbanezAbstract:Growth differentiation factor 11 (GDF11) contributes to regionalize the mouse embryo along its Anterior–Posterior Axis by regulating the expression of Hox genes. The identity of the receptors that mediate GDF11 signalling during embryogenesis remains unclear. Here, we show that GDF11 can interact with type I receptors ALK4, ALK5 and ALK7, but predominantly uses ALK4 and ALK5 to activate a Smad3-dependent reporter gene. Alk5 mutant embryos showed malformations in Anterior–Posterior patterning, including the lack of expression of the Posterior determinant Hoxc10, that resemble defects found in Gdf11-null mutants. A heterozygous mutation in Alk5, but not in Alk4 or Alk7, potentiated Gdf11−/−-like phenotypes in vertebral, kidney and palate development in an Acvr2b−/− background, indicating a genetic interaction between the two receptor genes. Thus, the transforming growth factor-β (TGF-β) receptor ALK5, which until now has only been associated with the biological functions of TGF-β1 to TGF-β3 proteins, mediates GDF11 signalling during embryogenesis.
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Growth differentiation factor 11 signals through the transforming growth factor‐β receptor ALK5 to regionalize the Anterior–Posterior Axis
EMBO Reports, 2006Co-Authors: Olov Andersson, Eva Reissmann, Carlos F IbanezAbstract:Growth differentiation factor 11 (GDF11) contributes to regionalize the mouse embryo along its Anterior–Posterior Axis by regulating the expression of Hox genes. The identity of the receptors that mediate GDF11 signalling during embryogenesis remains unclear. Here, we show that GDF11 can interact with type I receptors ALK4, ALK5 and ALK7, but predominantly uses ALK4 and ALK5 to activate a Smad3-dependent reporter gene. Alk5 mutant embryos showed malformations in Anterior–Posterior patterning, including the lack of expression of the Posterior determinant Hoxc10, that resemble defects found in Gdf11-null mutants. A heterozygous mutation in Alk5, but not in Alk4 or Alk7, potentiated Gdf11−/−-like phenotypes in vertebral, kidney and palate development in an Acvr2b−/− background, indicating a genetic interaction between the two receptor genes. Thus, the transforming growth factor-β (TGF-β) receptor ALK5, which until now has only been associated with the biological functions of TGF-β1 to TGF-β3 proteins, mediates GDF11 signalling during embryogenesis.
Sebastian M. Shimeld - One of the best experts on this subject based on the ideXlab platform.
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retinoic acid hox genes and the Anterior Posterior Axis in chordates
BioEssays, 1996Co-Authors: Sebastian M. ShimeldAbstract:In vertebrate development, the HOX genes act to specify cell identity along much of the Anterior-Posterior Axis of the embryonic central nervous system. In all vertebrates examined to date, the vitamin A metabolite retinoic acid is implicated in the patterning of the Anterior Posterior Axis and the induction of HOX gene expression. Two recent papers have extended the study of retinoic acid induction of HOX genes to the closest relatives of the vertebrates, amphioxus and tunicates(1,2). In both these species, exogenous retinoic acid is able to induce ectopic expression of HOX 1 genes in the Anterior central nervous system. This suggests that retinoic acid control of Anterior-Posterior Axis formation and HOX induction is not specific to vertebrates. However, in the more distantly related echinoderms and arthropods, retinoic acid does not seem to act in the same way. Thus the role of retinoic acid in Anterior-Posterior Axis specification may be a chordate innovation, perhaps linked to the evolution of another chordate character, the dorsal neural tube.
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Retinoic acid, HOX genes and the Anterior‐Posterior Axis in chordates
BioEssays, 1996Co-Authors: Sebastian M. ShimeldAbstract:In vertebrate development, the HOX genes act to specify cell identity along much of the Anterior-Posterior Axis of the embryonic central nervous system. In all vertebrates examined to date, the vitamin A metabolite retinoic acid is implicated in the patterning of the Anterior Posterior Axis and the induction of HOX gene expression. Two recent papers have extended the study of retinoic acid induction of HOX genes to the closest relatives of the vertebrates, amphioxus and tunicates(1,2). In both these species, exogenous retinoic acid is able to induce ectopic expression of HOX 1 genes in the Anterior central nervous system. This suggests that retinoic acid control of Anterior-Posterior Axis formation and HOX induction is not specific to vertebrates. However, in the more distantly related echinoderms and arthropods, retinoic acid does not seem to act in the same way. Thus the role of retinoic acid in Anterior-Posterior Axis specification may be a chordate innovation, perhaps linked to the evolution of another chordate character, the dorsal neural tube.
Lars Schwabe - One of the best experts on this subject based on the ideXlab platform.
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Time-dependent memory transformation along the hippocampal Anterior–Posterior Axis
Nature Communications, 2018Co-Authors: Lisa C. Dandolo, Lars SchwabeAbstract:With time, memories undergo a neural reorganization that is linked to a transformation of detailed, episodic into more semantic, gist-like memory. Traditionally, this reorganization is thought to involve a redistribution of memory from the hippocampus to neocortical areas. Here we report a time-dependent reorganization within the hippocampus, along its Anterior–Posterior Axis, that is related to the transformation of detailed memories into gist-like representations. We show that mnemonic representations in the Anterior hippocampus are highly distinct and that Anterior hippocampal activity is associated with detailed memory but decreases over time. Posterior hippocampal representations, however, are more gist-like at a later retention interval, and do not decline over time. These findings indicate that, in addition to the well-known systems consolidation from hippocampus to neocortex, there are changes within the hippocampus that are crucial for the temporal dynamics of memory. Detailed memories are transformed into gist-like memories over time. Here, the authors report that this change is linked to a time-dependent reorganization within the hippocampus, such that Anterior activity supporting memory specificity declines over time while Posterior activity patterns carrying gist representations remain more stable.
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Time-dependent memory transformation along the hippocampal Anterior-Posterior Axis.
Nature communications, 2018Co-Authors: Lisa C. Dandolo, Lars SchwabeAbstract:With time, memories undergo a neural reorganization that is linked to a transformation of detailed, episodic into more semantic, gist-like memory. Traditionally, this reorganization is thought to involve a redistribution of memory from the hippocampus to neocortical areas. Here we report a time-dependent reorganization within the hippocampus, along its Anterior–Posterior Axis, that is related to the transformation of detailed memories into gist-like representations. We show that mnemonic representations in the Anterior hippocampus are highly distinct and that Anterior hippocampal activity is associated with detailed memory but decreases over time. Posterior hippocampal representations, however, are more gist-like at a later retention interval, and do not decline over time. These findings indicate that, in addition to the well-known systems consolidation from hippocampus to neocortex, there are changes within the hippocampus that are crucial for the temporal dynamics of memory. Detailed memories are transformed into gist-like memories over time. Here, the authors report that this change is linked to a time-dependent reorganization within the hippocampus, such that Anterior activity supporting memory specificity declines over time while Posterior activity patterns carrying gist representations remain more stable.
Jonathan S. Marchant - One of the best experts on this subject based on the ideXlab platform.
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planarian Anterior Posterior Axis is established by interaction of voltage dependent ca2 influx and β catenin signaling at the early stage of regeneration
Developmental Biology, 2009Co-Authors: Taisaku Nogi, Dan Zhang, John D. Chan, Jonathan S. MarchantAbstract:Concurrent session 3: Mechanisms of developmental patterning Program/Abstract # 18 Dynamic interpretation of the Hedgehog gradient drives wing disc patterning in Drosophila Marcos Nahmad, Angela Stathopoulos Department of CDS, Caltech, Pasadena, CA, USA Div. of Biol., Caltech, Pasadena, CA, USA Morphogens are classically defined as molecules that control patterning by acting at a distance to regulate gene expression in a concentration-dependent manner. In the Drosophila wing imaginal disc, secreted Hedgehog (Hh) forms an extracellular gradient that organizes patterning along the Anterior–Posterior Axis by defining at least three different domains of gene expression. However, a direct spatial correspondence between the boundaries of these patterns and Hh-concentration thresholds has not been demonstrated. We have acquired evidence that the interpretation of Hh signaling depends on the history of exposure to Hh and that a single concentration threshold is sufficient to support multiple outputs. Mathematical modeling and computer simulations suggest that a spatial ‘overshoot’ of the Hh gradient occurs, that is, a transient gradient in which the Hh-concentration profile is expanded compared to the steady-state gradient. This overshoot results from the gene network architecture, in particular, it depends on Hh-dependent up-regulation of the Hh receptor, Patched (Ptc). Through a temporal examination of Hh-target gene expression in vivo, we observe that particular borders of expression shift Posteriorly, and subsequently refine. Furthermore, when the network structure is altered such that Ptc transcription is no longer activated in response to Hh signaling, we find that the patterns of gene expression, which have distinct borders in wild-type discs, now in fact overlap. Taken together, our results demonstrate that the overshoot of the Hh gradient is necessary to establish different patterns of gene expression. doi:10.1016/j.ydbio.2009.05.025 Program/Abstract # 19 Planarian Anterior–Posterior Axis is established by interaction of voltage-dependent Ca influx and β-catenin signaling at the early stage of regeneration Taisaku Nogi, Dan Zhang, John D. Chan, Jonathan S. Marchant Department of Pharmacology and The Stem Cell Institute, University of Minnesota Medical School, MN, USA Since the classic experiments of Marsh and Beams in the 1950s, it has been suggested that endogenous voltage gradients play an important role in planarian regeneration. Here, we show voltagedependent Ca influx is a key regulator of Anterior–Posterior (AP) Axis specification during planarian regeneration. Using a pharmacological screen of Ca signaling modulators in the planarian D. japonica, we identified that praziquantel (PZQ) – a voltage-operated Ca channel (VOCC) activator – had a robust effect to yield a bipolar (two-headed) phenotype from regenerating trunk fragments. PZQtreated fragments displayed a mirror-imaged pharynx and Posterior, rather than ectopic, head. This effect was Ca-dependent and increased by a variety of depolarizing agents known to couple to VOCCs. Time-window experiments and in situ hybridization of marker gene expression demonstrated PZQ treatment impacted the early stages of regeneration (<18 h post amputation) and produced a complete Anteriorization. Chemical genetic analysis identified that Ltype voltage-operated Cachannel (VOCC) β subunits were essential for PZQ action as in vivo RNAi for βsubunits counteracted PZQ-evoked bipolarity. Finally, β-catenin RNAi and PZQ co-treatment synergistically caused the bipolar phenotype, suggesting PZQ-evoked Ca signals inhibit Wnt/β-catenin signaling. Taken together, these data suggest voltage-dependent Ca influx is an upstream factor to Wnt/ β-catenin signals that establish AP Axis polarity during planarian regeneration. doi:10.1016/j.ydbio.2009.05.026 Program/Abstract # 20 The diverse functions of transcriptional factor AP2 (TFAP2) targets in neural crest development Ting Thalia Luo, Yan Xu, Janaki Rangarajan, Trevor Hoffman, Yoo-Seok Hwang, Thomas Schilling, Thomas Sargent Lab. of Mol. Genet., NICHD/NIH, Bethesda, MD 20892, USA Department of Dev. and Cell. Biol. Univ. of California, Irvine, CA 92697, USA Neural crest (NC) cells are a unique feature of vertebrate embryos, arising from the border of neural and non-neural ectoderm as the result of inductive signals including BMP and Wnt, among others. NC cells migrate extensively to give rise to a wide variety of cell lineages, i.e., the craniofacial bones, pigment cells, neurons and glia of the peripheral nervous system. We showed that the transcription factor AP2 (TFAP2) plays an important role in regulating gene expression in NC cells, and is positively regulated by BMP and Wnt. By the microarray approach, we have identified three predominantly NC expressed genes as TFAP2 targets: PCNS, Myosin X (MyoX) and Inca, were intensively studied in the Xenopus and zebrafish by in vivo and in vitro. PCNS is a novel protocadherin which appears to regulate cadherin mediated cell–cell adhesion. MyoX is a non-muscle myosin known to play important roles in the formation of filopodia and cell Developmental Biology 331 (2009) 390–391
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Planarian Anterior–Posterior Axis is established by interaction of voltage-dependent Ca2+ influx and β-catenin signaling at the early stage of regeneration
Developmental Biology, 2009Co-Authors: Taisaku Nogi, Dan Zhang, John D. Chan, Jonathan S. MarchantAbstract:Concurrent session 3: Mechanisms of developmental patterning Program/Abstract # 18 Dynamic interpretation of the Hedgehog gradient drives wing disc patterning in Drosophila Marcos Nahmad, Angela Stathopoulos Department of CDS, Caltech, Pasadena, CA, USA Div. of Biol., Caltech, Pasadena, CA, USA Morphogens are classically defined as molecules that control patterning by acting at a distance to regulate gene expression in a concentration-dependent manner. In the Drosophila wing imaginal disc, secreted Hedgehog (Hh) forms an extracellular gradient that organizes patterning along the Anterior–Posterior Axis by defining at least three different domains of gene expression. However, a direct spatial correspondence between the boundaries of these patterns and Hh-concentration thresholds has not been demonstrated. We have acquired evidence that the interpretation of Hh signaling depends on the history of exposure to Hh and that a single concentration threshold is sufficient to support multiple outputs. Mathematical modeling and computer simulations suggest that a spatial ‘overshoot’ of the Hh gradient occurs, that is, a transient gradient in which the Hh-concentration profile is expanded compared to the steady-state gradient. This overshoot results from the gene network architecture, in particular, it depends on Hh-dependent up-regulation of the Hh receptor, Patched (Ptc). Through a temporal examination of Hh-target gene expression in vivo, we observe that particular borders of expression shift Posteriorly, and subsequently refine. Furthermore, when the network structure is altered such that Ptc transcription is no longer activated in response to Hh signaling, we find that the patterns of gene expression, which have distinct borders in wild-type discs, now in fact overlap. Taken together, our results demonstrate that the overshoot of the Hh gradient is necessary to establish different patterns of gene expression. doi:10.1016/j.ydbio.2009.05.025 Program/Abstract # 19 Planarian Anterior–Posterior Axis is established by interaction of voltage-dependent Ca influx and β-catenin signaling at the early stage of regeneration Taisaku Nogi, Dan Zhang, John D. Chan, Jonathan S. Marchant Department of Pharmacology and The Stem Cell Institute, University of Minnesota Medical School, MN, USA Since the classic experiments of Marsh and Beams in the 1950s, it has been suggested that endogenous voltage gradients play an important role in planarian regeneration. Here, we show voltagedependent Ca influx is a key regulator of Anterior–Posterior (AP) Axis specification during planarian regeneration. Using a pharmacological screen of Ca signaling modulators in the planarian D. japonica, we identified that praziquantel (PZQ) – a voltage-operated Ca channel (VOCC) activator – had a robust effect to yield a bipolar (two-headed) phenotype from regenerating trunk fragments. PZQtreated fragments displayed a mirror-imaged pharynx and Posterior, rather than ectopic, head. This effect was Ca-dependent and increased by a variety of depolarizing agents known to couple to VOCCs. Time-window experiments and in situ hybridization of marker gene expression demonstrated PZQ treatment impacted the early stages of regeneration (
R. Valentini - One of the best experts on this subject based on the ideXlab platform.
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Stabilometric analysis after percutaneous of ruptured Achilles tendon repair
2002Co-Authors: B. Martinelli, V. Cimarosti, R. ValentiniAbstract:the Achilles tendon, without residual functional deficit despite increased Achilles tendon thickness and sural triceps hypotrophy, underwent stabilometric analysis to detect any unsettled mechanism in postural control. The analysis was performed using a platform equipped with sensors to detect sole pressures, which was connected to a computer that calculates the average centre of pressure and a series of parameters related to centre of pressure sway. As no statistically significant differences were found in the parameters between the patients and a control group of 14 healthy volunteers, a study was undertaken to better understand the differences in reaction between the two limbs, particularly as regards the leg-foot system. V(Y) is a parameter that measures the average speed of the centre of pressure sway on the Anterior-Posterior Axis. In all 14 patients it was greater in the operated limb, suggesting worse control on the Anterior-Posterior Axis.
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Stabilometric analysis after percutaneous repair of ruptured Achilles tendon
Foot and Ankle Surgery, 2002Co-Authors: B. Martinelli, V. Cimarosti, R. ValentiniAbstract:Summary Fourteen patients treated with percutaneous repair following rupture of the Achilles tendon, without residual functional deficit despite increased Achilles tendon thickness and sural triceps hypotrophy, underwent stabilometric analysis to detect any unsettled mechanism in postural control. The analysis was performed using a platform equipped with sensors to detect sole pressures, which was connected to a computer that calculates the average centre of pressure and a series of parameters related to centre of pressure sway. As no statistically significant differences were found in the parameters between the patients and a control group of 14 healthy volunteers, a study was undertaken to better understand the differences in reaction between the two limbs, particularly as regards the leg-foot system. V(Y) is a parameter that measures the average speed of the centre of pressure sway on the Anterior-Posterior Axis. In all 14 patients it was greater in the operated limb, suggesting worse control on the Anterior-Posterior Axis.
