Search

Histochemical detection of tartrate-resistant acid phosphatase (TRAP) activity is a fundamental technique for visualizing osteoclastic bone resorption and assessing osteoclast activity status in tissues. This approach has mostly employed colorimetric detection, which has limited quantification of activity in situ and co-labelling with other skeletal markers. Here we report simple colorimetric and fluorescent TRAP assays in zebrafish and medaka, two important model organisms for investigating the pathogenesis of bone disorders. We show fluorescent TRAP staining, utilising the ELF97 substrate, is a rapid, robust and stable system to visualise and quantify osteoclast activity in zebrafish, and is compatible with other fluorescence stains, transgenic lines and antibody approaches. Using this approach, we show that TRAP activity is predominantly found around the base of the zebrafish pharyngeal teeth, where osteoclast activity state appears to be heterogeneous. Published version

During bone development and repair, osteoblasts are recruited to bone deposition sites. To identify the origin of recruited osteoblasts, cell lineage tracing using Cre/loxP recombination is commonly used. However, a confounding factor is the use of transgenic Cre drivers that do not accurately recapitulate endogenous gene expression or the use of knock-in Cre drivers that alter endogenous protein activity or levels. Here, we describe a CRISPR/Cas9 homology-directed repair knock-in approach that allows efficient generation of Cre drivers controlled by the endogenous gene promoter. In addition, a self-cleaving peptide preserves the reading frame of the endogenous protein. Using this approach, we generated col10a1p2a-CreERT2 knock-in medaka and show that tamoxifen-inducible CreERT2 efficiently recombined loxP sites in col10a1 cells. Similar knock-in efficiencies were obtained when two unrelated loci (osr1 and col2a1a) were targeted. Using live imaging, we traced the fate of col10a1 osteoblast progenitors during bone lesion repair in the medaka vertebral column. We show that col10a1 cells at neural arches represent a mobilizable cellular source for bone repair. Together, our study describes a previously unreported strategy for precise cell lineage tracing via efficient and non-disruptive knock-in of Cre.

Matrix metalloproteases (MMPs) play crucial roles in extracellular matrix (ECM) modulation during osteoclast-driven bone remodeling. In the present study, we used transcriptome profiling of bone cells in a medaka model for osteoporosis and bone regeneration to identify factors critical for bone remodeling and homeostasis. This identified

Purpose The purpose of this paper is to provide a process view into moments of entrepreneurial crisis within the venture formation process caused by environmental stressors. A new construct is conceptualized, the entrepreneurial breaking point (EBP), as a critical and potentially insurmountable moment of crisis caused by an entrepreneur’s appraisal of environmental threats during a new venture’s formation. Design/methodology/approach To develop the EBP within a process model, this study builds upon previous environmental frameworks by expanding upon and infusing a situated social cognitive approach with a stress perspective. Findings The theoretical framework developed sheds light on the complex person-environment interaction that can create an EBP, the process of experiencing an EBP, how individuals vary in their activation of coping resources to respond to an EBP and how an EBP can ultimately result in new venture exit, sustained performance or growth. Practical implications The paper discusses implications for entrepreneurs during these moments of crises, including suggesting the use of trusted, impartial third-parties to overcome individual weaknesses, increasing awareness of the various environmental threats and finding a balance between goal-related commitment and adaptation. Originality/value This paper contributes to the existing literature by operationalizing and contextualizing a special case of socio-cognition under duress, filling an identified need for process work, exploring some reasons for EBP response variation across different entrepreneurs and elaborating on how the behavioral outcomes of an EBP may affect venture performance.

Abnormal blood flow mechanics can result in pathological heart malformation, underlining the importance of understanding embryonic cardiac fluid mechanics. In the current study, we performed image-based computational fluid dynamics simulation of the zebrafish embryonic heart ventricles and characterized flow mechanics, organ dynamics, and energy dynamics in detail. 4D scans of 5 days post-fertilization embryonic hearts with GFP-labelled myocardium were acquired using line-scan focal modulation microscopy. This revealed that the zebrafish hearts exhibited a wave-like contractile/relaxation motion from the inlet to the outlet during both systole and diastole, which we showed to be an energy efficient configuration. No impedance pumping effects of pressure and velocity waves were observed. Due to its tube-like configuration, inflow velocities were higher near the inlet and smaller at the outlet and vice versa for outflow velocities. This resulted in an interesting spatial wall shear stress (WSS) pattern where WSS waveforms near the inlet and those near the outlet were out of phase. There was large spatial variability in WSS magnitudes. Peak WSS was in the range of 47.5–130 dyne/cm2 at the inflow and outflow tracts, but were much smaller, in the range of 4–11 dyne/cm2, in the mid-ventricular segment. Due to very low Reynolds number and the highly viscous environment, intraventricular pressure gradients were high, suggesting substantial energy losses of flow through the heart.

Multifunctional adhesives out of a polymer matrix and electrically conductive fillers are known to typically decrease in bond strength with increasing filler content, while the electrical r...

Based on the economic theory of dual structure, the authors of this study conducted an empirical analysis on the relationship between entrepreneurship and poverty alleviation using panel da...

This manuscript presents an empirically tested model of entrepreneurial intentions based upon social cognitive career theory (SCCT). Our study consisted of 320 undergraduate business studen...

Summary Displacement experiments have demonstrated that experienced migratory birds translocated thousands of kilometers away from their migratory corridor can orient toward and ultimately reach their intended destinations. 1 This implies that they are capable of “true navigation,” commonly defined 2 , 3 , 4 as the ability to return to a known destination after displacement to an unknown location without relying on familiar surroundings, cues that emanate from the destination, or information collected during the outward journey. 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 In birds, true navigation appears to require previous migratory experience 5 , 6 , 7 , 14 , 15 (but see Kishkinev et al. 16 and Piersma et al. 17 ). It is generally assumed that, to correct for displacements outside the familiar area, birds initially gather information within their year-round distribution range, learn predictable spatial gradients of environmental cues within it, and extrapolate from those to unfamiliar magnitudes—the gradient hypothesis. 6 , 9 , 18 , 19 , 20 , 21 , 22 However, the nature of the cues and evidence for actual extrapolation remain elusive. Geomagnetic cues (inclination, declination, and total intensity) provide predictable spatial gradients across large parts of the globe and could serve for navigation. We tested the orientation of long-distance migrants, Eurasian reed warblers, exposing them to geomagnetic cues of unfamiliar magnitude encountered beyond their natural distribution range. The birds demonstrated re-orientation toward their migratory corridor as if they were translocated to the corresponding location but only when all naturally occurring magnetic cues were presented, not when declination was changed alone. This result represents direct evidence for migratory birds’ ability to navigate using geomagnetic cues extrapolated beyond their previous experience.

As a ubiquitous environmental pollutant, benzo[a]pyrene (BaP) has been extensively studied for over 80 years. While much research has focused on its genotoxic and carcinogenic effects, considerably less attention has been paid to the osteotoxicity of BaP. Notably, environmental exposure to BaP is associated with skeletal malformation and bone impairment. Recent studies indicated that ancestral BaP exposure can cause transgenerational osteotoxicity in the unexposed F3 offspring. The consequences of environmental BaP/PAH pollution are thus likely to be severe and require re-assessment. We have reviewed the research status of BaP osteotoxicity, and a summary of genetic and epigenetic factors in the regulation of bone metabolism is provided as the basis for elucidating the mechanisms underlying transgenerational BaP osteotoxicity. Based on published studies on this topic, we propose that the transgenerational inheritance of osteotoxicity in fish induced by ancestral BaP exposure is mediated via epigenetically dysregulated bone miRNAs/genes. Two possible epigenetic regulatory circuits of BaP on bone miRNAs and genes are proposed: (i) bone miRNAs are dysregulated via altered DNA methylation and/or histone modifications, affecting target gene expression/activity; (ii) dysregulation of bone genes through altered DNA methylation and/or histone modifications. Our proposed mode of action (MOA) intends to serve as a basis for hypothesis testing in further in-depth studies. We emphasize that future works must verify the proposed MOA to assess its human relevance, and to decipher the underlying mechanism(s) of transgenerational BaP osteotoxicity.

The European Space Agency's INTErnational Gamma-Ray Astrophysics Laboratory (ESA/INTEGRAL) was launched aboard a Proton-DM2 rocket on 17 October 2002 at 06:41 CEST, from Baikonur in Kazakhstan. Since then, INTEGRAL has been providing long, uninterrupted observations (up to about 47h, or 170ksec, per satellite orbit of 2.7 days) with a large field-of-view (FOV, fully coded: 100 deg), millisecond time resolution, keV energy resolution, polarization measurements, as well as additional wavelength coverage at optical wavelengths. This is realized by two main instruments in the 15keV to 10MeV energy range, the spectrometer SPI (spectral resolution 3keV at 1.8MeV) and the imager IBIS (angular resolution: 12arcmin FWHM), complemented by X-ray (JEM-X; 3–35keV) and optical (OMC; Johnson V-band) monitor instruments. All instruments are co-aligned to simultaneously observe the target region. A particle radiation monitor (IREM) measures charged particle fluxes near the spacecraft. The Anti-coincidence subsystems of the main instruments, built to reduce the background, are also very efficient all-sky γ-ray detectors, which provide virtually omni-directional monitoring above ∼75keV. Besides the long, scheduled observations, INTEGRAL can rapidly (within a couple of hours) re-point and conduct Target of Opportunity (ToO) observations on a large variety of sources. INTEGRAL observations and their scientific results have been building an impressive legacy: The discovery of currently more than 600 new high-energy sources; the first-ever direct detection of Ni and Co radio-active decay lines from a Type Ia supernova; spectroscopy of isotopes from galactic nucleo-synthesis sources; new insights on enigmatic positron annihilation in the Galactic bulge and disk; and pioneering gamma-ray polarization studies. INTEGRAL is also a successful actor in the new multi-messenger astronomy introduced by non-electromagnetic signals from gravitational waves and from neutrinos: INTEGRAL found the first prompt electromagnetic radiation in coincidence with a binary neutron star merger. Up to now more than 1750 scientific papers based on INTEGRAL data have been published in refereed journals. In this paper, we will give a comprehensive update of the satellite status after more than 18 years of operations in a harsh space environment, and an account of the successful Ground Segment., Kuulkers, Erik, et al., he OMC team has been funded by different Spanish grants, including Spanish State Research Agency grants PID2019–107061GB–C61 and MDM–2017-0737 (Unidad de Excelencia María de Maeztu – CAB). The INTEGRAL French teams acknowledge partial funding from the French Space Agency (CNES). The Danish JEM-X gratefully acknowledges support from the Danish PRODEX delegation through contract C90057. The INTEGRAL Italian team acknowledges support form the Italian Space Agency, ASI, along these years via different agreements, last of which is 2019–35-HH.0. LH acknowledges support from SFI under grant 19/FFP/6777 and the EU AHEAD2020 project (grant agreement 871158). MH acknowledges support from Spanish MICINN grant PID2019-108709GB-I00. TS is supported by the German Research Society (DFG-Forschungsstipendium SI 2502/1-1 & SI 2502/3-1).

The INTEGRAL hard X-ray surveys have proven to be of fundamental importance. INTEGRAL has mapped the Galactic plane with its large field of view and excellent sensitivity. Such hard X-ray snapshots of the whole Milky Way on a time scale of a year are beyond the capabilities of past and current narrow-FOV grazing incidence X-ray telescopes. By expanding the INTEGRAL X-ray survey into shorter timescales, a productive search for transient X-ray emitters was made possible. In more than fifteen years of operation, the INTEGRAL observatory has given us a sharper view of the hard X-ray sky, and provided the triggers for many follow-up campaigns from radio frequencies to gamma-rays. In addition to conducting a census of hard X-ray sources across the entire sky, INTEGRAL has carried out, through Earth occultation maneuvers, unique observations of the large-scale cosmic X-ray background, which will without question be included in the annals of X-ray astronomy as one of the mission's most salient contribution to our understanding of the hard X-ray sky., Comment: 23 pages, 16 figures, 1 table, will be published in New Astronomy Reviews issue 15 years of INTEGRAL science

The threat of climate change is forcing the world to decarbonize all economic sectors. Ammonia primarily used for fertilizer production and a potential, ‘hydrogen carrier’ currently accounts for ~27% of global hydrogen consumption and ~1% of global greenhouse gas emissions. In this analysis, we assess the techno-economic potential of ammonia production using onshore wind, open-field photovoltaic and batteries for both domestic usage and export scenarios in India, which is currently one of the world's largest producer and importer of ammonia. Our results reveal that India's potential can comfortably satisfy global ammonia demand with lowest ammonia costs of 723 EUR/tNH3 and 765 EUR/tNH3 for the domestic and export scenario, respectively. To compete with conventional ammonia production a carbon tax of 224–335 €/tCO2 would be required. Finally, costs of shipping liquid hydrogen and the ‘hydrogen carrier’ ammonia are similar here giving other economic, environmental and safety factors higher relevance.

Neurexins are presynaptic transmembrane proteins that control synapse activity and are risk factors for autism spectrum disorder. Zebrafish, a popular model for behavioral studies, has six neurexin genes, but their functions in embryogenesis and behavior remain largely unknown. We have previously reported that nrxn2a is aberrantly spliced and specifically dysregulated in motor neurons (MNs) in models of spinal muscular atrophy. In this study, we generated nrxn2aa−/− mutants by CRISPR/Cas9 to understand nrxn2aa function at the zebrafish neuromuscular junction (NMJ) and to determine the effects of its deficiency on adult behavior. Homozygous mutant embryos derived from heterozygous parents did not show obvious defects in axon outgrowth or synaptogenesis of MNs. In contrast, maternal-zygotic (MZ) nrxn2aa−/− mutants displayed extensively branched axons and defective MNs, suggesting a cell-autonomous role for maternally provided nrxn2aa in MN development. Analysis of the NMJs revealed enlarged choice points in MNs of mutant larvae and reduced co-localization of pre- and post-synaptic terminals, indicating impaired synapse formation. Severe early NMJ defects partially recovered in late embryos when mutant transcripts became strongly upregulated. Ultimately, however, the induced defects resulted in muscular atrophy symptoms in adult MZ mutants. Zygotic homozygous mutants developed normally but displayed increased anxiety at adult stages. Together, our data demonstrate an essential role for maternal nrxn2aa in NMJ synapse establishment, while zygotic nrxn2aa expression appears dispensable for synapse maintenance. The viable nrxn2aa−/− mutant furthermore serves as a novel model to study how an increase in anxiety-like behaviors impacts other deficits.

In mammals, osteoclasts differentiate from macrophages in the monocyte lineage. Although many factors driving osteoclast formation are known, the detailed processes underlying precursor recruitment, differentiation, and interaction of macrophages with other cell types involved in bone remodeling are poorly understood. Using live imaging in a transgenic medaka osteoporosis model, where ectopic osteoclasts are induced by RANKL expression, we show that a subset of macrophages is recruited to bone matrix to physically interact with bone‐forming osteoblast progenitors. These macrophages subsequently differentiate into cathepsin K‐ (ctsk‐) positive osteoclasts. One day later, other macrophages are recruited to clear dying osteoclasts from resorbed bone by phagocytosis. To better understand the molecular changes underlying these dynamic processes, we performed transcriptome profiling of activated macrophages upon RANKL induction. This revealed an upregulation of several bone‐related transcripts. Besides osteoclast markers, we unexpectedly also found expression of osteoblast‐promoting signals in activated macrophages, suggesting a possible non‐cell autonomous role in osteogenesis. Finally, we show that macrophage differentiation into osteoclasts is dependent on inflammatory signals. Medaka deficient for TNFα or treated with the TNFα‐inhibitor pentoxifylline exhibited impaired macrophage recruitment and osteoclast differentiation. These results show the involvement of inflammatory signals and the dynamics of a distinct subset of macrophages during osteoclast formation. © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Ancestral benzo[

Sexual selection results in sex-specific characters like the conspicuously pigmented extension of the ventral tip of the caudal fin - the “sword” - in males of several species of Xiphophorus fishes. To uncover the genetic architecture underlying sword formation and to identify genes that are associated with its development, we characterized the sword transcriptional profile and combined it with genetic mapping approaches. Results showed that the male ornament of swordtails develops from a sexually non-dimorphic prepattern of transcription factors in the caudal fin. Among genes that constitute the exclusive sword transcriptome only two are located in the genomic region associated with this trait; the chaperone, fkbp9, and the potassium channel, kcnh8 that in addition to its neural function performs a role known to affect fin growth. This indicates that during evolution of swordtails a brain gene has been recruited for an additional function in establishing a male ornament.

Flight passenger behavior comprises, for example, booking requests as well as cancelations and the no-show phenomenon before the departure of an airplane while airline fleet assignment describes the task of putting together among other things—but above all—an attractive schedule of origin–destination flight connections with corresponding takeoff and landing times. We propose an approach that takes into account the interrelations between flight passenger behavior and airline fleet assignment and integrates aircraft-type allocation to flight legs, the treatment of different booking classes, the offering of specific as well as flexible products to flight passengers, and overbooking decisions to avoid empty seats in airplanes. An exemplary description of how the new approach reacts to alterations of the underlying situation is added to show the flexibility and advantages of our model formulation.

This study applies action research (AR)—defined as a cyclical process of continuous improvement of practical and real-life problems—to investigate the evolution of a voluntary, noncredit, collaborative coworking environment for student entrepreneurs at a nonresidential college. The goal of the article is to illustrate how entrepreneurship educators can use AR as a catalyst to continuously improve entrepreneurship education environments based on a deeper understanding of students’ needs and entrepreneurial development levels. We conclude with a general reflection about the AR project and the implications of AR to the larger entrepreneurship education context.

In the following study, we investigated thermally and photolytically induced transformations of acylcyclotetrasilanes (Me3Si)2Si4Me8(Me3Si)COR (compounds 9a-c; R = alkyl, aryl). Mild thermolysis of 9a-c below 130 °C cleanly and selectively afforded the corresponding endocyclic silenes 10b-d irrespective of the nature of the substituents at the carbonyl moiety. Thus, the previously unknown heterocyclopolysilane 10b could be isolated by crystallization and fully characterized including single crystal X-ray crystallography. Upon photolysis with light of λ ≥ 300 nm 9a-c showed Brook type 1,3-Si → O migration reactions under formation of the silenes 10a-c with exo- and endocyclic Si C double bonds. In this case the substituent at the carbonyl moiety largely determines the type of the resulting silene. Contrary to alkyl substituted educts, which form both types of silenes, aryl substituted acylcyclotetrasilanes exclusively afford the endocyclic derivative. 10b,c were photochemically unstable and underwent different degradation processes while 10d was surprisingly stable under similar conditions. Photolysis of 9a-c, in the presence of methanol, cleanly afforded the expected 1,2-addition products of the Si C double bond.

Nonmammalian vertebrates have the capacity of lifelong tooth replacement. In all vertebrates, tooth formation requires contact and interaction between the oral or pharyngeal epithelium and the underlying mesenchyme. To secure lifelong replacement, the presence of odontogenic stem cells has been postulated, particularly in the epithelial compartment. This study uses an advanced teleost fish species, the marine medaka Oryzias melastigma, a close relative to Oryzias latipes, to examine the expression and distribution of telomerase reverse transcriptase (Tert), the catalytic unit of telomerase, in developing pharyngeal teeth and to relate these data to the proliferative activity of the cells. The data are complemented by expression analysis of the pluripotency marker oct4 and bona fide stem cell marker lgr5. Tert distribution and tert expression in developing tooth germs show a dynamic spatiotemporal pattern. Tert is present first in the mesenchyme but is downregulated as the odontoblasts differentiate. In contrast, in the epithelial enamel organ, Tert is absent during early stages of tooth formation and upregulated first in ameloblasts. Later, Tert is expressed and immunolocalized throughout the entire inner enamel epithelium. The pattern of Tert distribution is largely mutually exclusive with that of proliferating cell nuclear antigen (PCNA) immunoreactivity: highly proliferative cells, as revealed by PCNA staining, are negative for Tert; conversely, PCNA-negative cells are Tert-positive. Only the early condensed mesenchyme is both Tert- and PCNA-positive. The absence of tert-positive cells in the epithelial compartment of early tooth germs is underscored by the absence of oct4- and lgr5-positive cells, suggesting ways other than stem cell involvement to secure continuous renewal.

Die Kühlung von Gebäuden und der damit verbundene Energieeinsatz gewinnen zunehmend an Bedeutung. Gerade bei großen Gebäuden, bei denen sich, bedingt durch ihre Nutzung, die benötigte Kälteleistung in größeren Dimensionen bewegt, kann die Nutzung von regenerativen Energien einen ganz besonderen Beitrag zum Umweltschutz und zur Ressourcenschonung darstellen. Diese Metadaten wurden zur Verfügung gestellt von der Literaturdatenbank RSWB®plus

Data literacy has become a critical skill to deal with the complexities of the information-driven society of the 21st century. At the same time, data visualization has long escaped the boundaries of science and has become a pervasive - often unrecognized - part of our everyday lives. In this paper, we introduce Diagram Safari, an educational game to foster data literacy among children 9 to 11 years old by teaching about diagrams and charts in a playful manner. We report on the iterative design process and on a preliminary evaluation with 23 children showing that the game was well received and that the difficulty was appropriate for the target audience.

Wie diagnostiziert man Beeinträchtigungen bei Entwicklungsverzögerungen im Vorschulalter, Lern-, Leistungs- und Verhaltensproblemen sowie Behinderungen unterschiedlicher Art bei Kindern und Jugendlichen? Wie leitet man adäquate Fördermaßnahmen aus der Diagnose ab? Das Standardwerk der sonder- und heilpädagogischen Diagnostik erläutert förderdiagnostische Sichtweisen und Methoden und informiert lernzielorientiert über - wissenschafts- und testtheoretische Grundlagen, - die Praxis der Förderdiagnostik in einzelnen Anwendungsfeldern, - forderungsorientierte, sonderpädagogische Gutachtenerstellung.

The identification of disease-causing mutations has in recent years progressed immensely due to whole genome sequencing approaches using patient material. The task accordingly is shifting from gene identification to functional analysis of putative disease-causing genes, preferably in an in vivo setting which also allows testing of drug candidates or biotherapeutics in whole animal disease models. In this review, we highlight the advances made in the field of bone diseases using small laboratory fish, focusing on zebrafish and medaka. We particularly highlight those human conditions where teleost models are available.

Given the limitations and side effects of many synthetic drugs, natural products are an important alternative source for drugs and medications for many diseases. Icariin (ICA), one of the main flavonoids from plants of the Epimedium genus, has been shown to ameliorate osteoporosis and improve bone health in preclinical studies. Those studies have used different in vivo models, mostly rodents, but the underlying mechanisms remain unclear. The present study shows, for the first time, that ICA reduces bone damage in a Rankl-induced medaka fish (Oryzias latipes), a non-rodent osteoporosis model. Live imaging was previously performed in this model to characterize antiresorptive and bone-anabolic properties of drugs. Here, a new quantification method (IM ) was established based on the length of mineralized neural arches to quantify levels of bone mineralization damage and protection in early post-embryonic fish. This method was validated by quantification of three levels of bone damage in three independent Rankl fish lines, and by the determination of different degrees of severity of osteoporosis-like phenotypes in one Rankl line exposed to variable Rankl induction schemes. IM was also used to quantify the efficacy of alendronate and etidronate, two common anti-osteoporotic bisphosphonates, and revealed comparable bone protective effects for ICA and alendronate in this fish osteoporosis model. This study's data support the value of the medaka fish model for bone research and establish a method to screen for novel osteoprotective compounds.

Aviation data comprise, e.g., bookings and cancellations by consumers as well as no show situations before departure, aircraft-type assignments to flight legs and overbooking-decisions to avoid empty seats in airplanes. Here deterministic linear programming (DLP) is a widely used approach to process this kind of data in an area called airline network revenue management for which adaptions of a basic DLP-model to overbooking situations as well as the offering of flexible products are known. We combine these concepts in a model which simultaneously allows the incorporation of overbooking-decisions and the offering of specific as well as flexible products. Additionally, we further extend this integrated formulation to allow the treatment of different booking-classes and aircraft-type assignment considerations. We present characteristics of the new approach, which uses the overlapping science directions of data analysis and operations research, point out differences to already known results in airline network revenue management, describe an example which illustrates how the different aspects can be considered, and indicate the advantages of our model in view of various data settings.

Osteoporosis is an increasing burden on public health as the world-wide population ages and effective therapeutics are severely needed. Two pathways with high potential for osteoporosis treatment are the retinoic acid (RA) and endocannabinoid system (ECS) signaling pathways. We sought to elucidate the roles that these pathways play in bone development and maturation. Here, we use chemical treatments to modulate the RA and ECS pathways at distinct early, intermediate, and late times bone development in zebrafish. We further assessed osteoclast activity later in zebrafish and medaka. Finally, by combining sub-optimal doses of AR and ECS modulators, we show that enhancing RA signaling or reducing the ECS promote bone formation and decrease osteoclast abundance and activity. These data demonstrate that RA signaling and the ECS can be combined as sub-optimal doses to influence bone growth and may be key targets for potential therapeutics.

Recent studies from mammalian, fish, and in vitro models have identified bone and cartilage development as sensitive targets for dioxins and other aryl hydrocarbon receptor ligands. In this study, we assess how embryonic 2,3,7,8-tetrachlorochlorodibenzo-p-dioxin (TCDD) exposure impacts axial osteogenesis in Japanese medaka (Oryzias latipes), a vertebrate model of human bone development. Embryos from inbred wild-type Orange-red Hd-dR and 3 transgenic medaka lines (twist:EGFP, osx/sp7:mCherry, col10a1:nlGFP) were exposed to 0.15 nM and 0.3 nM TCDD and reared until 20 dpf. Individuals were stained for mineralized bone and imaged using confocal microscopy to assess skeletal alterations in medial vertebrae in combination with a qualitative spatial analysis of osteoblast and osteoblast progenitor cell populations. Exposure to TCDD resulted in an overall attenuation of vertebral ossification characterized by truncated centra, and reduced neural and hemal arch lengths. Effects on mineralization were consistent with modifications in cell number and cell localization of transgene-labeled osteoblast and osteoblast progenitor cells. Endogenous expression of osteogenic regulators runt-related transcription factor 2 (runx2) and osterix (osx/sp7), and extracellular matrix genes osteopontin (spp1), collagen type I alpha I (col1), collagen type X alpha I (col10a1), and osteocalcin (bglap/osc) was significantly diminished at 20 dpf following TCDD exposure as compared with controls. Through global transcriptomic analysis more than 590 differentially expressed genes were identified and mapped to select pathological states including inflammatory disease, connective tissue disorders, and skeletal and muscular disorders. Taken together, results from this study suggest that TCDD exposure inhibits axial bone formation through dysregulation of osteoblast differentiation. This approach highlights the advantages and sensitivity of using small fish models to investigate how xenobiotic exposure may impact skeletal development.

This paper examines the choices of retail investors in the market for structured financial products with a focus on implicit and explicit pricing components. We evaluate more than 72,000 single stock discount certificates on a daily basis from 2004 through 2008. The certificates are quoted an average of 0.58% above their fair value before the financial crisis, increasing to 1.24% during 2008. Although credit risk explains a major part (39%) of the certificates’ overpricing, we find that issuer default risk does not have any influence on investors’ product choices. Instead, retail investors are strongly influenced by irrational factors such as issuer and product familiarity. Finally, investors are found to make poor product choices (in terms of bid/ask spreads and markups over fair value), resulting in significant losses.