FGF-10 Stimulates Limb Regeneration Ability in Xenopus laevis

AbstractBy reciprocal transplantation experiments with regenerative and nonregenerative Xenopus limbs, we recently demonstrated that the regenerative capacity of a Xenopus limb depends on mesenchymal tissue and we suggested that fgf-10 is likely to be involved in this capacity (Yokoyama et al., 2000, Dev. Biol. 219, 18–29). However, the data obtained in that study are not conclusive evidence that FGF-10 is responsible for the regenerative capacity. We therefore investigated the role of FGF-10 in regenerative capacity by directly introducing FGF-10 protein into nonregenerative Xenopus limb stumps. Exogenously applied FGF-10 successfully stimulated the regenerative capacity, resulting in the reinduction of all gene expressions (including shh, msx-1, and fgf-10) that we examined and the regeneration of well-patterned limb structures. We report here for the first time that a certain molecule activates the regenerative capacity of Xenopus limb, and this finding suggests that FGF-10 could be a key molecule in possible regeneration of nonregenerative limbs in higher vertebrates

Ephrin-A2 regulates position-specific cell affinity and is involved in cartilage morphogenesis in the chick limb bud

AbstractIn the developing limb bud, mesenchymal cells show position-specific affinity, suggesting that the positional identity of the cells is represented as their surface properties. Since the affinity is regulated by glycosylphosphatidylinositol (GPI)-anchored cell surface proteins, and by EphA4 receptor tyrosine kinase, we hypothesized that the GPI-anchored ligand, the ephrin-A family, also contributes to the affinity. Here, we describe the role of ephrin-A2 in the chick limb bud. Ephrin-A2 protein is uniformly distributed in the limb bud during early limb development. As the limb bud grows, expression of ephrin-A2 is strong in its proximal-to-intermediate regions, but weak distally. The position-dependent expression is maintained in vitro, and is regulated by FGF protein, which is produced in the apical ectodermal ridge. To investigate the role of ephrin-A2 in affinity and in cartilage morphogenesis of limb mesenchyme, we ectopically expressed ephrin-A2 in the limb bud using the retrovirus vector, RCAS. Overexpressed ephrin-A2 modulated the affinity of the mesenchymal cells that differentiate into autopod elements. It also caused malformation of the autopod skeleton and interfered with cartilage nodule formation in vitro without inhibiting chondrogenesis. These results suggest that ephrin-A2 regulates the position-specific affinity of limb mesenchyme and is involved in cartilage pattern formation in the limb

Glycosylphosphatidylinositol-Anchored Cell Surface Proteins Regulate Position-Specific Cell Affinity in the Limb Bud

AbstractAlthough regional differences in mesenchymal cell affinity in the limb bud represent positional identity, the molecular basis for cell affinity is poorly understood. We found that treatment of the cell surface with bacterial phosphatidylinositol-specific phospholipase C (PI-PLC) could change cell affinity in culture. When PI-PLC was added to the culture medium, segregation of the progress zone (PZ) cells from different stage limb buds was inhibited. Similarly, sorting out of the cells from different positions along the proximodistal (PD) axis of the same stage limb buds was disturbed. Since PI-PLC can remove glycosylphosphatidylinositol (GPI)-anchored membrane bound proteins from the cell surface, the GPI-anchored cell surface proteins may be involved in sorting out. To define the GPI-anchored molecules that determine the segregation of limb mesenchymal cells, we examined the effect of neutralizing antibody on the EphA4 receptor that binds to GPI-anchored cell surface ligands, called ephrin-A. Sorting out of the PZ cells at different stages could be inhibited by the neutralizing antibody to EphA4. These results suggest that EphA4 and its GPI-anchored ligands are, at least in part, involved in sorting out of limb mesenchymal cells with different proximal–distal positional values, and that GPI-anchored cell surface proteins play important roles in determining cell affinity in the limb bud

Multiple Digit Formation inXenopusLimb Bud Recombinants

AbstractWe prepared recombinant limb buds ofXenopustadpoles by grafting a mesenchyme mass of the hindlimb bud. TheXenopusrecombinant limb buds with dissociated and reaggregated mesenchyme developed more than 30 digits with cartilage segmentation, while those with undissociated mesenchyme developed a limb with normal cartilage pattern. Before the formation of multiple digits, a patchy expression pattern offgf-8,an AER marker, was observed in the distal region of recombinant limb buds.shh,a ZPA (zone of polarizing activity) marker, was expressed broadly in the distal region of recombinants. Recombinant limb buds with the reaggregated mesenchyme of anterior halves formed anterior digits with claws, and those with the mesenchyme of posterior halves formed posterior digits without claws. The temporal and spatial changes in the potency of multiple digit formation are discussed with reference to the regenerative capacity ofXenopuslimb buds

英国小説史におけるサミュエル・リチャードソンの文学の意味

金沢大学教養学部研究課題/領域番号:X40440-----13168, 研究期間(年度):1965出典：研究課題「英国小説史におけるサミュエル・リチャードソンの文学の意味」課題番号X40440-----13168（KAKEN：科学研究費助成事業データベース（国立情報学研究所）） （https://kaken.nii.ac.jp/ja/grant/KAKENHI-PROJECT-X40440-----13168/）を加工して作

A New Method for Calculating Arrival Distribution of Ultra-High Energy Cosmic Rays above 10^19 eV with Modifications by the Galactic Magnetic Field

We present a new method for calculating arrival distribution of UHECRs including modifications by the galactic magnetic field. We perform numerical simulations of UHE anti-protons, which are injected isotropically at the earth, in the Galaxy and record the directions of velocities at the earth and outside the Galaxy for all of the trajectories. We then select some of them so that the resultant mapping of the velocity directions outside the Galaxy of the selected trajectories corresponds to a given source location scenario, applying Liouville's theorem. We also consider energy loss processes of UHE protons in the intergalactic space. Applying this method to our source location scenario which is adopted in our recent study and can explain the AGASA observation above 4 \times 10^{19} eV, we calculate the arrival distribution of UHECRs including lower energy (E>10^19 eV) ones. We find that our source model can reproduce the large-scale isotropy and the small-scale anisotropy on UHECR arrival distribution above 10^19 eV observed by the AGASA. We also demonstrate the UHECR arrival distribution above 10^19 eV with the event number expected by future experiments in the next few years. The interesting feature of the resultant arrival distribution is the arrangement of the clustered events in the order of their energies, reflecting the directions of the galactic magnetic field. This is also pointed out by Alvarez-Muniz et al.(2002). This feature will allow us to obtain some kind of information about the composition of UHECRs and the magnetic field with increasing amount of data.Comment: 10 pages, 8 figures, to appear in the Astrophysical Journa

FGF7 and FGF10 Directly Induce the Apical Ectodermal Ridge in Chick Embryos

AbstractDuring 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

A Hilbert warping method for camera-based finger-writing recognition, in:

Abstract We propose a time-warping algorithm for recognizing finger actions by a camera. In the proposed method, an input image sequence is aligned to the reference sequences by phase-synchronization of the analytic signals, and then classified by comparing the cumulative distances. A major benefit of this method is that overfitting to sequences of incorrect categories is restricted. The proposed method exhibited high recognition accuracy in finger-writing character recognition

Ergonomic dual four-bar linkage knee exoskeleton for stair ascent assistance

Introduction: Robotic exoskeletons are emerging technologies that have demonstrated their effectiveness in assisting with Activities of Daily Living. However, kinematic disparities between human and robotic joints can result in misalignment between humans and exoskeletons, leading to discomfort and potential user injuries.Methods: In this paper, we present an ergonomic knee exoskeleton based on a dual four-bar linkage mechanism powered by hydraulic artificial muscles for stair ascent assistance. The device comprises two asymmetric four-bar linkage mechanisms on the medial and lateral sides to accommodate the internal rotation of the knee and address the kinematic discrepancies between these sides. A genetic algorithm was employed to optimize the parameters of the four-bar linkage mechanism to minimize misalignment between human and exoskeleton knee joints. The proposed device was evaluated through two experiments. The first experiment measured the reduction in undesired load due to misalignment, while the second experiment evaluated the device’s effectiveness in assisting stair ascent in a healthy subject.Results: The experimental results indicate that the proposed device has a significantly reduced undesired load compared to the traditional revolute joint, decreasing from 14.15 N and 18.32 N to 1.88 N and 1.07 N on the medial and lateral sides, respectively. Moreover, a substantial reduction in muscle activities during stair ascent was observed, with a 55.94% reduction in surface electromyography signal.Discussion: The reduced undesired load of the proposed dual four-bar linkage mechanism highlights the importance of the adopted asymmetrical design for reduced misalignment and increased comfort. Moreover, the proposed device was effective at reducing the effort required during stair ascent