Insights into the Understanding of the Nickel-Based Pre-Catalyst Effect on Urea Oxidation Reaction Activity.

Nickel-based catalysts are regarded as the most excellent urea oxidation reaction (UOR) catalysts in alkaline media. Whatever kind of nickel-based catalysts is utilized to catalyze UOR, it is widely believed that the in situ-formed Ni3+ moieties are the true active sites and the as-utilized nickel-based catalysts just serve as pre-catalysts. Digging the pre-catalyst effect on the activity of Ni3+ moieties helps to better design nickel-based catalysts. Herein, five different anions of OH-, CO32-, SiO32-, MoO42-, and WO42- were used to bond with Ni2+ to fabricate the pre-catalysts ß-Ni(OH)2, Ni-CO3, Ni-SiO3, Ni-MoO4, and Ni-WO4. It is found that the true active sites of the five as-fabricated catalysts are the same in situ-formed Ni3+ moieties and the five as-fabricated catalysts demonstrate different UOR activity. Although the as-synthesized five catalysts just serve as the pre-catalysts, they determine the quantity of active sites and activity per active site, thus determining the catalytic activity of the catalysts. Among the five catalysts, the amorphous nickel tungstate exhibits the most superior activity per active site and can catalyze UOR to reach 158.10 mA·cm-2 at 1.6 V, exceeding the majority of catalysts. This work makes for a deeper understanding of the pre-catalyst effect on UOR activity and helps to better design nickel-based UOR catalysts.

Optical section structured illumination-based Förster resonance energy transfer imaging.

Förster resonance energy transfer (FRET) microscopy is an important tool suitable for studying molecular interactions in living cells. Optical section structured illumination microscopy (OS-SIM), like confocal microscopy, has about 200 nm spatial resolution. In this report, we performed quantitative 3-cube FRET imaging in OS-SIM mode and widefield microscopy (WF) mode, respectively, for living cells expressing FRET constructs consisting of Cerulean (C, donor) and Venus (V, acceptor). OS-SIM images exhibited higher resolution than WF images. Four spectral crosstalk coefficients measured under OS-SIM mode are consistent with those measured under WF mode. Similarly, the system calibration factors G and k measured under OS-SIM mode were consistent with those measured under WF mode. The measured FRET efficiency (E) values of C32V and C17V as well as C5V constructs, standard FRET plasmids, in living Hela cells were EC32VOSF=0.32±0.02,EC17VOSF=0.38±0.02 , and EC5VOSF=0.45±0.03 , and the measured acceptor-to-donor concentration ratios ( Rc ) were RC32VOSF=1.07±0.03 , RC17VOSF=1.09±0.03 , and RC5VOSF=1.02±0.04 , consistent with the reported values. Collectively, our data demonstrates that OS-SIM can be integrated into FRET microscopy to build an OS-SIM-FRET with confocal microscopy-like resolution.

Measuring calibration factors by imaging a dish of cells expressing different tandem constructs plasmids.

Three-cube Förster resonance energy transfer (FRET) method is the most extensively applied approach for live-cell FRET quantification. Reliable measurements of calibration factors are crucial for quantitative FRET measurement. We here proposed a modified TA-G method (termed as mTA-G) to simultaneously obtain the FRET-sensitized quenching transition factor (G) and extinction coefficients ratio (γ) between donor and acceptor. mTA-G method includes four steps: (1) predetermining the ratio ranges of the sensitized emission of acceptor (FC ) to the donor excitation and donor channel image (IDD [(DA])) for all FRET plasmids; (2) culturing the cells which express every FRET plasmid in one dish respectively; (3) distinguishing and marking the cells expressing different FRET plasmids by detecting their FC /IDD (DA) values; (4) linearly fitting FC /IAA (DA) (acceptor excitation and acceptor channel image) to IDD (DA)/IAA (DA) for different kinds of cells. We implemented mTA-G method by imaging tandem constructs cells with different FRET efficiency cultured in one dish on different days, and obtained consistent G and γ values. mTA-G method not only circumvents switchover of different culture dishes but also keep the constant imaging conditions, exhibiting excellent robustness, and thus will expands the biological applications of quantitative FRET analysis in living cells.

Stiffness Modulation in Flexible Rotational Triboelectric Nanogenerators for Dual Enhancement of Power and Reliability.

Rotational nanogenerators with flexible triboelectric layers have wide applications and high reliability. However, flexible materials cause a severe reduction in contact force and thus triboelectric output power. Unlike previous works devising complex auxiliary structures to solve this issue, this paper focuses on improving the contact material mechanics and proposes a stiffness modulation method. By introducing fine patterns to the contacting rotor-stator pairs, the effective elastic modulus was regulated from approximately 103 to 105 MPa, and the output voltage was modulated from approximately 24.39% to 375.87% compared to the non-patterned rotor-stator pairs, corresponding to a maximal a 14 times increase in output power. A maximal power density of 18.75 W/m2 was achieved on 10 MΩ resistance at 9.6 Hz, which is even beyond the power density of most rigid triboelectric interfaces. Moreover, high reliability could be maintained when the volume ratio of the horizontal patterns exceeded a threshold value of 33.5% as the stator and 63.6% as the rotor for a 0.5 mm linewidth. These results prove the efficacy of the stiffness modulation method for jointly achieving high output power and high reliability in flexible rotational triboelectric nanogenerators.

An ultra-soft conductive elastomer for multifunctional tactile sensors with high range and sensitivity.

Flexible tactile sensors have become important as essential tools for facilitating human and object interactions. However, the materials utilized for the electrodes of capacitive tactile sensors often cannot simultaneously exhibit high conductivity, low modulus, and strong adhesiveness. This limitation restricts their application on flexible interfaces and results in device failure due to mechanical mismatch. Herein, we report an ultra-low modulus, highly conductive, and adhesive elastomer and utilize it to fabricate a microstructure-coupled multifunctional flexible tactile sensor. We prepare a supramolecular conductive composite film (SCCF) as the electrode of the tactile sensor using a supramolecular deep eutectic solvent, polyvinyl alcohol (PVA) solution, poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), and MXene suspension. We employ a polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) film containing 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIM:TFSI) as the dielectric layer to fabricate capacitive sensors with an electrical double layer structure. Furthermore, we enhance the performance of the device by incorporating coupled pyramid and dome microstructures, which endow the sensor with multi-directional force detection. Our SCCF exhibits extremely high conductivity (reaching 710 S cm-1), ultra-low modulus (0.8 MPa), and excellent interface adhesion strength (>120 J m-2). Additionally, due to the outstanding conductivity and unique structure of the SCCF, it possesses remarkable electromagnetic shielding ability (>50 dB). Moreover, our device demonstrates a high sensitivity of up to 1756 kPa-1 and a wide working range reaching 400 kPa, combining these attributes with the requirements of an ultra-soft human-machine interface to ensure optimal contact between the sensor and interface materials. This innovative and flexible tactile sensor holds great promise and potential for addressing various and complex demands of human-machine interaction.

Bioinspired electrically stable, optically tunable thermal management electronic skin via interfacial self-assembly.

The skin is the largest organ in the human body and serves vital functions such as sensation, thermal management, and protection. While electronic skin (E-skin) has made significant progress in sensory functions, achieving adaptive thermal management akin to human skin has remained a challenge. Drawing inspiration from squid skin, we have developed a hybrid electronic-photonic skin (hEP-skin) using an elastomer semi-embedded with aligned silver nanowires through interfacial self-assembly. With mechanically adjustable optical properties, the hEP-skin demonstrates adaptive thermal management abilities, warming in the range of +3.5°C for heat preservation and cooling in the range of -4.2°C for passive cooling. Furthermore, it exhibits an ultra-stable high electrical conductivity of âˆ¼4.5×104 S/cm, even under stretching, bending or torsional deformations over 10,000 cycles. As a proof of demonstration, the hEP-skin successfully integrates stretchable light-emitting electronic skin with adaptive thermal management photonic skin.

Perturbation of zebrafish swimbladder development by enhancing Wnt signaling in Wif1 morphants.

Wnt signaling plays critical roles in development of both tetrapod lung and fish swimbladder, which are the two evolutionary homologous organs. Our previous data reveal that down-regulation of Wnt signaling leads to defective swimbladder development. However, the effects of up-regulation of Wnt signaling on swimbladder development remain unclear. By knockdown of the Wnt protein inhibitory gene wif1, we demonstrated that up-regulation of Wnt signaling also resulted in perturbed development of the swimbladder. Specifically, the growth of epithelium and mesenchyme was greatly inhibited, the smooth muscle differentiation was abolished, and the organization of mesothelium was disturbed. Furthermore, our data reveal that it is the reduced cell proliferation, but not enhanced apoptosis, that contributes to the disturbance of swimbladder development in wif1 morphants. Blocking Wnt signaling by the Wnt antagonist IWR-1 did not affect wif1 expression in the swimbladder, but complete suppression of Hedgehog signaling in smo-/- mutants abolished wif expression, consistent with our earlier report of a negative feedback regulation of Wnt signaling in the swimbladder by the Hedgehog signaling. Our works established the importance of proper level of Wnt signaling for normal development of swimbladder in zebrafish.

Current status of diagnosis and treatment of pulmonary hypertension in Chinese tertiary hospitals: A nationwide survey.

We intended to evaluate the diagnosis and treatment status of pulmonary hypertension (PH) in China and provide the basis for the design of the Chinese PH centers system. A questionnaire survey was conducted by sampling from Chinese Class A tertiary hospitals that have carried out the clinical work of PH, including the composition of PH clinical team, the current application of examinations related to PH diagnosis, the availability of PAH-specific medicine and the implementation of PH-related intervention and surgery. A total of 44 valid questionnaires from 20 provinces were collected in this survey. In the vast majority of centers (83.33%, n = 35), pulmonary artery catheterization was routinely performed under X-ray guidance. In 19.05% (n = 8) of centers, pressure measurements were determined at the right time (the end of normal expiration). Only 73.81% (n = 31) centers have carried out acute vasoreactivity testing. Prostacyclin analogues and prostaglandin receptor agonists were just prescribed in 45.45% (n = 20) of the centers. 19 centers (43.18%) were capable of performing balloon pulmonary angioplasty (BPA) and pulmonary endarterectomy (PEA), while 25% (n = 11) were able to perform BPA, PEA, and lung transplantation. There was no significant difference in the diagnosis and treatment of PH between economic regions. The majority of Chinese tertiary hospitals were well equipped with the corresponding personnel, examinations and medicines related to PH, but the standardization and specialization of the management of PH need to be strengthened.

A comparative study on the diagnostic efficacy of different diagnostic criteria for exercise pulmonary hypertension.

BACKGROUND: Exercise pulmonary hypertension (ePH) has three common diagnostic criteria: the mean pulmonary artery pressure (mPAP) > 30 mmHg and total pulmonary resistance (TPR) at peak exercise >3 Wood units ("Joint criteria"), the mPAP/cardiac output (CO) slope of the two-point measurement (ΔmPAP/ΔCO) > 3 mmHg/L/min ("Two-point criteria"), and the mPAP/CO slope of the multi-point data >3 mmHg/L/min ("Multi-point criteria"). We compared the diagnostic efficacy of these criteria, which remain controversial. METHODS: Following resting right heart catheterization (RHC), all patients underwent exercise RHC (eRHC). The patients were divided into different ePH and non-exercise pulmonary hypertension (nPH) groups according to the above criteria. Joint criteria were used as the reference to compare the other two, namely diagnostic concordance, sensitivity and specificity. We conducted further analysis to determine the correlation between different diagnostic criteria grouping and the clinical severity of PH. RESULTS: Thirty-three patients with mPAPrest ≤ 20 mmHg were enrolled. a) Diagnostic concordance, sensitivity and specificity: compared with Joint criteria, the diagnostic concordances of Two-point criteria and Multi-point criteria were 78.8% (κ = 0.570, P < 0.01) and 90.9% (κ = 0.818, P < 0.01), respectively; the sensitivity of Two-point criteria was high (100%), but the specificity was poor (56.3%); however, Multi-point criteria exhibited higher sensitivity (94.1%) and specificity (87.5%). b) Clinically relevant analysis: a significant difference was observed in several clinical severity indicators between ePH and nPH patients according to Multi-point criteria grouping(all P < 0.05). CONCLUSION: Multi-point criteria are more clinically relevant and provide better diagnostic efficiency.

Highly sensitive, wide-pressure and low-frequency characterized pressure sensor based on piezoresistive-piezoelectric coupling effects in porous wood.

Lightweight and highly compressible materials have received considerable attention in flexible pressure sensing devices. In this study, a series of porous woods (PWs) are produced by chemical removal of lignin and hemicellulose from natural wood by tuning treatment time from 0 to 15 h and extra oxidation through H2O2. The prepared PWs with apparent densities varying from 95.9 to 46.16 mg/cm3 tend to form a wave-shaped interwoven structure with improved compressibility (up to 91.89 % strain under 100 kPa). The sensor assembled from PW with treatment time of 12 h (PW-12) exhibits the optimal piezoresistive-piezoelectric coupling sensing properties. For the piezoresistive properties, it has high stress sensitivity of 15.14 kPa-1, covering a wide linear working pressure range of 0.06-100 kPa. For its piezoelectric potential, PW-12 shows a sensitivity of 0.443 V·kPa-1 with ultralow frequency detection as low as 0.0028 Hz, and good cyclability over 60,000 cycles under 0.41 Hz. The nature-derived all-wood pressure sensor shows obvious superiority in the flexibility for power supply requirement. More importantly, it presents fully decoupled signals without cross-talks in the dual-sensing functionality. Sensor like this is capable of monitoring various dynamic human motions, making it an extremely promising candidate for the next generation artificial intelligence products.

The interaction of epithelial Ihha and mesenchymal Fgf10 in zebrafish esophageal and swimbladder development.

Developmental patterning and growth of the vertebrate digestive and respiratory tracts requires interactions between the epithelial endoderm and adjacent mesoderm. The esophagus is a specialized structure that connects the digestive and respiratory systems and its normal development is critical for both. Shh signaling from the epithelium regulates related aspects of mammalian and zebrafish digestive organ development and has a prominent effect on esophageal morphogenesis. The mechanisms underlying esophageal malformations, however, are poorly understood. Here, we show that zebrafish Ihha signaling from the epithelium acting in parallel, but independently of Shh, controls epithelial and mesenchymal cell proliferation and differentiation of smooth muscles and neurons in the gut and swimbladder. In zebrafish ihha mutants, the esophageal and swimbladder epithelium is dysmorphic, and expression of fgf10 in adjacent mesenchymal cells is affected. Analysis of the development of the esophagus and swimbladder in fgf10 mutant daedalus (dae) and compound dae/ihha mutants shows that the Ihha-Fgf10 regulatory interaction is realized through a signaling feedback loop between the Ihha-expressing epithelium and Fgf10-expressing mesenchyme. Disruption of this loop further affects the esophageal and swimbladder epithelium in ihha mutants, and Ihha acts in parallel to but independently of Shha in this process. These findings contribute to the understanding of epithelial-mesenchymal interactions and highlight an interaction between Hh and Fgf signaling pathways during esophagus and swimbladder development.

Self-Powered Multifunctional Electronic Skin Based on Carbon Nanotubes/Poly(dimethylsiloxane) for Health Monitoring.

Flexible and multifunctional electronic skin (e-skin) has received remarkable attention for its potential applications in health monitoring, human-machine interface, and artificial sensory nerves. However, conventional multifunctional e-skins require complex material systems, sophisticated fabrication, and external power supplies, leading to increased preparation cost and duration, thus hindering their large-scale utilization. Herein, a self-powered multifunctional e-skin system with properties of pressure, temperature, underwater sensing, and photothermal heating is designed based on carbon nanotubes/poly(dimethylsiloxane) (CNT/PDMS) acting as both the multifunctional sensing layer and the cathode of the power supply. Our micropyramidal structured e-skin exhibits outstanding pressure sensitivity (1.51 × 103 kPa-1) over a wide sensing range (2.5-255.7 kPa) and maintains ultralong-term durability (>20 000 cycles). It can also provide personalized photothermal therapy at an adjustable temperature (40-110 °C) and heating area under near-infrared irradiation due to the photothermal effect of CNTs, with the temperature being detected synchronously by current signals. Additionally, the hydrophobicity of the CNT/PDMS film endows our device with underwater sensing capability. Furthermore, practical healthcare applications have been demonstrated with reliable signal quality and stability, such as daily activities and underwater movements/temperature monitoring, SOS Morse code communication, and human-machine interface. This work could provide insight on developing simple, stable, and wearable healthcare devices with self-power supply and multifunction.

Production of marker-free transgenic rice expressing tissue-specific Bt gene.

The hybrid Bacillus thuringiensis (Bt) δ-endotoxin gene Cry1Ab/Ac was used to develop a transgenic Bt rice (Oryza sativa L.) targeting lepidopteran insects of rice. Here, we show the production of a marker-free and tissue-specific expressing transgenic Bt rice line L24 using Agrobacterium-mediated transformation and a chemically regulated, Cre/loxP-mediated DNA recombination system. L24 carries a single copy of marker-free T-DNA that contains the Cry1Ab/Ac gene driven by a maize phosphoenolpyruvate carboxylase (PEPC) gene promoter. The marker-free T-DNA was integrated into the 3' untranslated region of rice gene Os01g0154500 on the short arm of chromosome 1. Compared to the constitutive and non-specific expression of the P (Actin1):Cry1Ab/Ac:T (Nos) gene in the control Bt rice line T51-1, the P ( Pepc ):Cry1Ab/Ac:T (Nos ) gene was detected only in the leaf and stem tissues of L24. More importantly, compared to high levels of CRY1Ab/Ac proteins accumulated in T51-1 seeds, the CRY1Ab/Ac proteins were not detectable in L24 seeds by Western blot analysis. As demonstrated by insect bioassay, L24 provided similar level of resistance to rice leaffolder (Cnaphalocrocis medinalis) as T51-1. The marker-free transgenic line L24 can be used directly in rice breeding for insect resistance to lepidopteran insects where absence of Bt toxin protein in the seed is highly desirable.

Privacy preserving anomaly detection based on local density estimation.

Anomaly detection has been widely researched in financial, biomedical and other areas. However, most existing algorithms have high time complexity. Another important problem is how to efficiently detect anomalies while protecting data privacy. In this paper, we propose a fast anomaly detection algorithm based on local density estimation (LDEM). The key insight of LDEM is a fast local density estimator, which estimates the local density of instances by the average density of all features. The local density of each feature can be estimated by the defined mapping function. Furthermore, we propose an efficient scheme named PPLDEM based on the proposed scheme and homomorphic encryption to detect anomaly instances in the case of multi-party participation. Compared with existing schemes with privacy preserving, our scheme needs less communication cost and less calculation cost. From security analysis, our scheme will not leak privacy information of participants. And experiments results show that our proposed scheme PPLDEM can detect anomaly instances effectively and efficiently, for example, the recognition of activities in clinical environments for healthy older people aged 66 to 86 years old using the wearable sensors.

Mediated Non-geminate Recombination in Ternary Organic Solar Cells Through a Liquid Crystal Guest Donor.

The approach via ternary blends prompts the increase of absorbed photon density and resultant photocurrent enhancement in organic solar cells (OSCs). In contrast to actively reported high efficiency ternary OSCs, little is known about charge recombination properties and carrier loss mechanisms in these emerging devices. Here, through introducing a small molecule donor BTR as a guest component to the PCE-10:PC71BM binary system, we show that photocarrier losses via recombination are mitigated with respect the binary OSCs, owing to a reduced bimolecular recombination. The gain of the fill factor in ternary devices are reconciled by the change in equilibrium between charge exaction and recombination in the presence of BTR toward the former process. With these modifications, the power conversion efficiency in ternary solar cells receives a boost from 8.8 (PCE-10:PC71BM) to 10.88%. We further found that the voltage losses in the ternary cell are slightly suppressed, related to the rising charge transfer-state energy. These benefits brought by the third guest donor are important for attaining improvements on key photophysical processes governing the photovoltaic efficiencies in organic ternary solar cells.

Bcl-xL inhibits PINK1/Parkin-dependent mitophagy by preventing mitochondrial Parkin accumulation.

This report aims to explore how Bcl-xL, a Bcl-2 family protein, regulates PINK1/Parkin-dependent mitophagy. Compared with the Hela cells expressing Parkin alone, co-expression of Bcl-xL significantly inhibited CCCP (Carbonyl cyanide 3- chlorophenylhydrazone)-induced mitochondrial Parkin accumulation and mitophagy. Western blotting analysis illustrated that over-expressed Bcl-xL inhibited CCCP-induced decrease of mitochondrial proteins in Parkin over-expressed cells. Fluorescence loss in photobleaching (FLIP) analyses demonstrated that Bcl-xL inhibited the CCCP-induced translocation of Parkin into mitochondria not by retrotranslocating Parkin from mitochondria to cytoplasm. Fluorescence resonance energy transfer (FRET) imaging revealed in Hela cells that Bcl-xL physically bound with Parkin to form oligomer in cytoplasm, and that Bcl-xL also directly interacted with PINK1 on mitochondria. analysis for HEK293 T cells verified that endogenous Bcl-xL interacted with both endogenous Parkin and PINK1. Collectively, Bcl-xL inhibits PINK1/Parkin- dependent mitophagy by preventing the accumulation of Parkin on mitochondria via two regulation ways: directly binds to Parkin in cytoplasm to prevent the translocation of Parkin from cytoplasm to mitochondria and directly binds to PINK1 on mitochondria to inhibit the Parkin from cytoplasm to mitochondria by PINK1.

Anomaly detection in ECG based on trend symbolic aggregate approximation.

ECG anomaly detection is a necessary approach to detect disease Electrocardiography( ECG) signals before the detail diagnosis process in medical field to gauge the health of the human heart. Nowadays, there are many anomaly detection methods for ECG detection including supervised learning and unsupervised learning. For supervised learning, it requires the knowledge of expert and different types of Arrhythmia data for training. However, since the anomalies are less and unknown in many cases which are di cult to distinguish and be labeled, unsupervised methods are more suitable to detect the ECG anomalies. Furthermore, the existing unsupervised learning studies do not take ECG shape into account where different diseases have different shapes. In this paper, a novel simple trend aggregate approximation method is proposed, the relative binary trend representation are used to record the shape feature in original time series and to detect the anomaly heart signals by similarity comparison. We use the ECG dataset in UCR Time Series Classification Archive to obtain ECG time series data and the experiment results are assessed by means of sensitivity, specificity, false alarm rate measures which is robust and promising with high accuracy.

Mitf is a transcriptional activator of medaka germ genes in culture.

Germ cells express a unique subset of genes called germ genes mostly encoding RNA-binding proteins such as Dazl, Dnd and Vasa. How germ gene expression is controlled remains illusive, because in no organism has a transcription factor been identified that regulate expression of these genes. Microphthalmia-associated transcription factor (Mitf) has been reported to show expression in male mouse germ cells of the adult testis. Here we report in the fish medaka (Oryzias latipes) that Mitf is a transcription activator of germ gene expression. Mitf is a master regulator of melanocyte development, which activates melanogenic genes through binding to the E-box containing consensus CANNTG. The E-box was found to be present in 23-26 copies in the promoters of medaka germ genes dazl, dnd and vasa. Importantly, forced Mitf expression enhanced the transcriptional activity of the three gene promoters by up to more than 10 fold and remarkably increased the level of endogenous dazl, dnd and vasa transcripts in cell culture. Transfection of Mitf expression vectors was sufficient to induce directed differentiation of medaka embryonic stem cells into melanocytes. Fluorescence in situ hybridization revealed the expression of both medaka mitf genes in adult germ cells of male and female gonads. Mitf is well-known as the melanocyte master regulator. Our results offer first evidence that Mitf may act as a transcriptional activator of germ gene expression in medaka.

Wnt signaling is required for early development of zebrafish swimbladder.

BACKGROUND: Wnt signaling plays critical roles in mammalian lung development. However, Wnt signaling in the development of the zebrafish swimbladder, which is considered as a counterpart of mammalian lungs, have not been explored. To investigate the potential conservation of signaling events in early development of the lung and swimbladder, we wish to address the question whether Wnt signaling plays a role in swimbladder development. METHODOLOGY/PRINCIPAL FINDINGS: For analysis of zebrafish swimbladder development, we first identified, by whole-mount in situ hybridization (WISH), has2 as a mesenchymal marker, sox2 as the earliest epithelial marker, as well as hprt1l and elovl1a as the earliest mesothelial markers. We also demonstrated that genes encoding Wnt signaling members Wnt5b, Fz2, Fz7b, Lef1, Tcf3 were expressed in different layers of swimbladder. Then we utilized the heat-shock inducible transgenic lines hs:Dkk1-GFP and hs:ΔTcf-GFP to temporarily block canonical Wnt signaling. Inhibition of canonical Wnt signaling at various time points disturbed precursor cells specification, organization, anterioposterior patterning, and smooth muscle differentiation in all three tissue layers of swimbladder. These observations were also confirmed by using a chemical inhibitor (IWR-1) of Wnt signaling. In addition, we found that Hedgehog (Hh) signaling was activated by canonical Wnt signaling and imposed a negative feedback on the latter. SIGNIFICANCE/CONCLUSION: We first provided a new set of gene markers for the three tissue layers of swimbladder in zebrafish and demonstrated the expression of several key genes of Wnt signaling pathway in developing swimbladder. Our functional analysis data indicated that Wnt/ß-catenin signaling is required for swimbladder early development and we also provided evidence for the crosstalk between Wnt and Hh signaling in early swimbladder development.

Expression of components of Wnt and Hedgehog pathways in different tissue layers during lung development in Xenopus laevis.

Although Wnt and Hedgehog (Hh) signaling pathways play important roles in mouse lung development, these have not been explored in the development of Xenopus lung. This may be due to the lack of specific molecular markers for different layers of tissue in Xenopus lung and/or insufficient knowledge on expression patterns of Wnt and Hh signaling components in Xenopus lung. In this study, we first described the early morphogenesis of Xenopus laevis lung by using surfactant protein C (sftpc) as a marker of lung epithelium and compared it with the expression patterns of several genes of Wnt and Hh pathways in Xenopus lungs. Our data showed that wnt7b was expressed in the entire lung epithelium from stage 37 to stage 45, while two other Wnt signaling components, wnt5a and wif1 (wnt inhibitory factor 1), were expressed in the mesenchyme layer of the entire lungs through stages 39-41. We also found that sonic hedgehog (shh) was expressed at stage 41 only in the anterior, but not in the posterior part of the lungs. These results show the expression of wnt5a, wnt7b, wif1 and shh in different layers of tissue of Xenopus lungs at early developmental stages, which implies different roles of these genes in the early development of Xenopus lungs. Our study for the first time defined specific molecular markers for description of early lung development in Xenopus, as well as provided information about expression of components of Wnt and Hh pathways in early Xenopus lungs, which should be useful for future functional studies.