Cloning and molecular analysis of paraxis: A {\it trans\/}-acting factor required for somite maturation

During vertebrate embryogenesis, cells from the paraxial mesoderm coalesce in a rostral-to-caudal progression to form the somites. Subsequent compartmentalization of the somites yields the sclerotome, myotome and dermatome, which give rise to the axial skeleton, axial musculature, and dermis, respectively. Recently, we cloned a novel basic-Helix-Loop-Helix (bHLH) protein, called scleraxis, which is expressed in the sclerotome, in mesenchymal precursors of bone and cartilage, and in connective tissues. This dissertation focuses on the cloning, expression and functional analysis of a bHLH protein termed paraxis, which is nearly identical to scleraxis within the bHLH region but diverges in both its amino and carboxyl termini. During the process of mouse embryogenesis, paraxis transcripts are first detected at about day 7.5 post coitum within the primitive mesoderm lying posterior to the head and heart primordia. Subsequently, paraxis expression progresses caudally through the paraxial mesoderm, immediately preceding somite formation. Paraxis is expressed at high levels in newly formed somites before the first detectable expression of the myogenic bHLH genes, and as the somite becomes compartmentalized, paraxis becomes downregulated within the myotome.^ To determine the function of paraxis during mammalian embryogenesis, mice were generated with a null mutation in the paraxis locus. Paraxis null mice survived until birth, but exhibited severe foreshortening along the anteroposterior axis due to the absence of vertebrae caudal to the midthoracic region. The phenotype also included axial skeletal defects, particularly shortened bifurcated ribs which were detached from the vertebral column, fused vertebrae and extensive truncation and disorganization caudal to the hindlimbs. Mutant neonates also lacked normal levels of trunk muscle and exhibited defects in the dermis as well as the stratification of the epidermis. Analysis of paraxis -/- mutant embryos has revealed a failure of the somites to both properly epithelialize and compartmentalize, resulting in defects in somite-derived cell lineages. These results suggest that paraxis is an essential component of the genetic pathway regulating somitogenesis. ^

La expresión de las emociones en relación al factor victoria durante la práctica de juegos deportivos

Este estudio tiene como objeto describir la relación entre la práctica de diferentes tipos de juegos motores reglamentados (juegos deportivos con o sin competición) y la expresión de las emociones. Los participantes fueron 726 estudiantes de actividad física y deportes del primer curso de facultades, escuelas de formación del profesorado y de animación deportiva de España y Portugal, a los que previamente se formó en la toma de conciencia en la expresión de las emociones. Realizaron ocho juegos deportivos correspondientes a los cuatro dominios de acción (psicomotriz (en solitario), cooperación, oposición y cooperación/oposición), siendo uno de cada de competición (lo cual implica la victoria o derrota de los participantes) y otro sin competición (nadie gana o pierde). Tras la realización de cada juego el participante registró en un cuestionario validado (Games and Emotions Scale (GES)) la intensidad alcanzada en cada una de las 13 emociones (clasificadas como positivas, negativas y ambiguas). Los resultados (tratamiento estadístico mediante ecuaciones de estimación generalizadas) muestran que la intensidad de las emociones positivas fueron en todos los juegos siempre muy superiores en comparación a la intensidad de las negativas y ambiguas. Ello nos puede confirmar el disfrute durante la práctica de los juegos deportivos. Dicho esto, se observa, por un lado, que la intensidad de las emociones positivas son ligeramente superiores en los juegos sin competición y, por otro lado, que la intensidad de las emociones es superior en la competición en comparación a los juegos sin competición, pero que esta superioridad se debe sobre todo a las emociones negativas y ambiguas. La medición, comparación, victoria y derrota inherentes a la competición puede tender a incrementar la frustración y el rechazo. Por último, se aprecian diferencias significativas entre los cuatro dominios al considerar si existe o no la victoria, especialmente para juegos cooperativos sin competición, donde la intensidad de las emociones positivas sube más que en los otros tipos de juegos y las negativas bajan, confirmando la conveniencia de los juegos cooperativos no competitivos en los programas educativos, reeducativos y recreativos, donde la superación del reto es una tarea colectiva

La expresión de las emociones en relación al factor victoria durante la práctica de juegos deportivos

Este estudio tiene como objeto describir la relación entre la práctica de diferentes tipos de juegos motores reglamentados (juegos deportivos con o sin competición) y la expresión de las emociones. Los participantes fueron 726 estudiantes de actividad física y deportes del primer curso de facultades, escuelas de formación del profesorado y de animación deportiva de España y Portugal, a los que previamente se formó en la toma de conciencia en la expresión de las emociones. Realizaron ocho juegos deportivos correspondientes a los cuatro dominios de acción (psicomotriz (en solitario), cooperación, oposición y cooperación/oposición), siendo uno de cada de competición (lo cual implica la victoria o derrota de los participantes) y otro sin competición (nadie gana o pierde). Tras la realización de cada juego el participante registró en un cuestionario validado (Games and Emotions Scale (GES)) la intensidad alcanzada en cada una de las 13 emociones (clasificadas como positivas, negativas y ambiguas). Los resultados (tratamiento estadístico mediante ecuaciones de estimación generalizadas) muestran que la intensidad de las emociones positivas fueron en todos los juegos siempre muy superiores en comparación a la intensidad de las negativas y ambiguas. Ello nos puede confirmar el disfrute durante la práctica de los juegos deportivos. Dicho esto, se observa, por un lado, que la intensidad de las emociones positivas son ligeramente superiores en los juegos sin competición y, por otro lado, que la intensidad de las emociones es superior en la competición en comparación a los juegos sin competición, pero que esta superioridad se debe sobre todo a las emociones negativas y ambiguas. La medición, comparación, victoria y derrota inherentes a la competición puede tender a incrementar la frustración y el rechazo. Por último, se aprecian diferencias significativas entre los cuatro dominios al considerar si existe o no la victoria, especialmente para juegos cooperativos sin competición, donde la intensidad de las emociones positivas sube más que en los otros tipos de juegos y las negativas bajan, confirmando la conveniencia de los juegos cooperativos no competitivos en los programas educativos, reeducativos y recreativos, donde la superación del reto es una tarea colectiva

La expresión de las emociones en relación al factor victoria durante la práctica de juegos deportivos

Este estudio tiene como objeto describir la relación entre la práctica de diferentes tipos de juegos motores reglamentados (juegos deportivos con o sin competición) y la expresión de las emociones. Los participantes fueron 726 estudiantes de actividad física y deportes del primer curso de facultades, escuelas de formación del profesorado y de animación deportiva de España y Portugal, a los que previamente se formó en la toma de conciencia en la expresión de las emociones. Realizaron ocho juegos deportivos correspondientes a los cuatro dominios de acción (psicomotriz (en solitario), cooperación, oposición y cooperación/oposición), siendo uno de cada de competición (lo cual implica la victoria o derrota de los participantes) y otro sin competición (nadie gana o pierde). Tras la realización de cada juego el participante registró en un cuestionario validado (Games and Emotions Scale (GES)) la intensidad alcanzada en cada una de las 13 emociones (clasificadas como positivas, negativas y ambiguas). Los resultados (tratamiento estadístico mediante ecuaciones de estimación generalizadas) muestran que la intensidad de las emociones positivas fueron en todos los juegos siempre muy superiores en comparación a la intensidad de las negativas y ambiguas. Ello nos puede confirmar el disfrute durante la práctica de los juegos deportivos. Dicho esto, se observa, por un lado, que la intensidad de las emociones positivas son ligeramente superiores en los juegos sin competición y, por otro lado, que la intensidad de las emociones es superior en la competición en comparación a los juegos sin competición, pero que esta superioridad se debe sobre todo a las emociones negativas y ambiguas. La medición, comparación, victoria y derrota inherentes a la competición puede tender a incrementar la frustración y el rechazo. Por último, se aprecian diferencias significativas entre los cuatro dominios al considerar si existe o no la victoria, especialmente para juegos cooperativos sin competición, donde la intensidad de las emociones positivas sube más que en los otros tipos de juegos y las negativas bajan, confirmando la conveniencia de los juegos cooperativos no competitivos en los programas educativos, reeducativos y recreativos, donde la superación del reto es una tarea colectiva

Predicting bed form roughness: the influence of lee side angle

Flow transverse bedforms (ripples and dunes) are ubiquitous in rivers and coastal seas. Local hydrodynamics and transport conditions depend on the size and geometry of these bedforms, as they constitute roughness elements at the bed. Bedform influence on flow energy must be considered for the understanding of flow dynamics, and in the development and application of numerical models. Common estimations or predictors of form roughness (friction factors) are based mostly on data of steep bedforms (with angle-of-repose lee slopes), and described by highly simplified bedform dimensions (heights and lengths). However, natural bedforms often are not steep, and differ in form and hydraulic effect relative to idealised bedforms. Based on systematic numerical model experiments, this study shows how the hydraulic effect of bedforms depends on the flow structure behind bedforms, which is determined by the bedform lee side angle, aspect ratio and relative height. Simulations reveal that flow separation behind bedform crests and, thus, a hydraulic effect is induced at lee side angles steeper than 11 to 18° depending on relative height, and that a fully developed flow separation zone exists only over bedforms with a lee side angle steeper than 24°. Furthermore, the hydraulic effect of bedforms with varying lee side angle is evaluated and a reduction function to common friction factors is proposed. A function is also developed for the Nikuradse roughness (k s), and a new equation is proposed which directly relates k s to bedform relative height, aspect ratio and lee side angle.

Are special economic zones a curse on those "chosen" to be evicted? : evidence form West Bengal, India

Using data from a self-administered survey of 1,017 households we assess the long-term impact of establishing a special economic zone, on those who are exogenously selected to be displaced. We find those who are displaced suffer from lower land compensation and lack of adequate property rights. There is also some evidence of lower labour market participation among those who are displaced. However, in the long term, across measurable welfare indicators, we do not find that displaced households are significantly different from other households. One source of this resilience is through employment at the special economic zone – which is higher among displaced households compared to other households. Another factor that contributed to the absence of differences is spill-over effects; which made access to employment, education and other facilities about homogenous across displaced and non-displaced households.

A note on three factor model of discounting

In Montiel Olea and Strzalecki (2014), authors have axiomatically developed an algorithm to infer the parameters of beta-delta model of cognitive bias (present and future biases). While this is extremely useful, it allows the implied beta to become very large when the response is impatient in the future choices relative to present choices, i.e., when there is a strong future bias. I modify the model to further exponentiate the functional form to get more reasonable beta values.

Inhibition of hypoxia-inducible factor 1 activity by nitric oxide donors in hypoxia

Nitric oxide (NO) is known to have various biologic and pathophysiologic effects on organisms. The molecular mechanisms by which NO exerts harmful effects are unknown, although various O2 radicals and ions that result from reactivity of NO are presumed to be involved. Here we report that adaptive cellular response controlled by the transcription factor hypoxia-inducible factor 1 (HIF-1) in hypoxia is suppressed by NO. Induction of erythropoietin and glycolytic aldolase A mRNAs in hypoxically cultured Hep3B cells, a human hepatoma cell line, was completely and partially inhibited, respectively, by the addition of sodium nitroprusside (SNP), which spontaneously releases NO. A reporter plasmid carrying four hypoxia-response element sequences connected to the luciferase structural gene was constructed and transfected into Hep3B cells. Inducibly expressed luciferase activity in hypoxia was inhibited by the addition of SNP and two other structurally different NO donors, S-nitroso-l-glutathione and 3-morpholinosydnonimine, giving IC50 values of 7.8, 211, and 490 μM, respectively. Inhibition by SNP was also observed in Neuro 2A and HeLa cells, indicating that the inhibition was not cell-type-specific. The vascular endothelial growth factor promoter activity that is controlled by HIF-1 was also inhibited by SNP (IC50 = 6.6 μM). Induction generated by the addition of cobalt ion (this treatment mimics hypoxia) was also inhibited by SNP (IC50 = 2.5 μM). Increased luciferase activity expressed by cotransfection of effector plasmids for HIF-1α or HIF-1α-like factor in hypoxia was also inhibited by the NO donor. We also showed that the inhibition was performed by blocking an activation step of HIF-1α to a DNA-binding form.

soc-2 encodes a leucine-rich repeat protein implicated in fibroblast growth factor receptor signaling

Activation of fibroblast growth factor (FGF) receptors elicits diverse cellular responses including growth, mitogenesis, migration, and differentiation. The intracellular signaling pathways that mediate these important processes are not well understood. In Caenorhabditis elegans, suppressors of clr-1 identify genes, termed soc genes, that potentially mediate or activate signaling through the EGL-15 FGF receptor. We demonstrate that three soc genes, soc-1, soc-2, and sem-5, suppress the activity of an activated form of the EGL-15 FGF receptor, consistent with the soc genes functioning downstream of EGL-15. We show that soc-2 encodes a protein composed almost entirely of leucine-rich repeats, a domain implicated in protein–protein interactions. We identified a putative human homolog, SHOC-2, which is 54% identical to SOC-2. We find that shoc-2 maps to 10q25, shoc-2 mRNA is expressed in all tissues assayed, and SHOC-2 protein is cytoplasmically localized. Within the leucine-rich repeats of both SOC-2 and SHOC-2 are two YXNX motifs that are potential tyrosine-phosphorylated docking sites for the SEM-5/GRB2 Src homology 2 domain. However, phosphorylation of these residues is not required for SOC-2 function in vivo, and SHOC-2 is not observed to be tyrosine phosphorylated in response to FGF stimulation. We conclude that this genetic system has allowed for the identification of a conserved gene implicated in mediating FGF receptor signaling in C. elegans.

Overexpression of transforming growth factor β1 in arterial endothelium causes hyperplasia, apoptosis, and cartilaginous metaplasia

Uninjured rat arteries transduced with an adenoviral vector expressing an active form of transforming growth factor β1 (TGF-β1) developed a cellular and matrix-rich neointima, with cartilaginous metaplasia of the vascular media. Explant cultures of transduced arteries showed that secretion of active TGF-β1 ceased by 4 weeks, the time of maximal intimal thickening. Between 4 and 8 weeks, the cartilaginous metaplasia resolved and the intimal lesions regressed almost completely, in large part because of massive apoptosis. Thus, locally expressed TGF-β1 promotes intimal growth and appears to cause transdifferentiation of vascular smooth muscle cells into chondrocytes. Moreover, TGF-β1 withdrawal is associated with regression of vascular lesions. These data suggest an unexpected plasticity of the adult vascular smooth muscle cell phenotype and provide an etiology for cartilaginous metaplasia of the arterial wall. Our observations may help to reconcile divergent views of the role of TGF-β1 in vascular disease.

Chymase cleavage of stem cell factor yields a bioactive, soluble product

Stem cell factor (SCF) is produced by stromal cells as a membrane-bound molecule, which may be proteolytically cleaved at a site close to the membrane to produce a soluble bioactive form. The proteases producing this cleavage are unknown. In this study, we demonstrate that human mast cell chymase, a chymotrypsin-like protease, cleaves SCF at a novel site. Cleavage is at the peptide bond between Phe-158 and Met-159, which are encoded by exon 6 of the SCF gene. This cleavage results in a soluble bioactive product that is 7 amino acids shorter at the C terminus than previously identified soluble SCF. This research shows the identification of a physiologically relevant enzyme that specifically cleaves SCF. Because mast cells express the KIT protein, the receptor for SCF, and respond to SCF by proliferation and degranulation, this observation identifies a possible feedback loop in which chymase released from mast cell secretory granules may solubilize SCF bound to the membrane of surrounding stromal cells. The liberated soluble SCF may in turn stimulate mast cell proliferation and differentiated functions; this loop could contribute to abnormal accumulations of mast cells in the skin and hyperpigmentation at sites of chronic cutaneous inflammation.

The roles of the two proton input channels in cytochrome c oxidase from Rhodobacter sphaeroides probed by the effects of site-directed mutations on time-resolved electrogenic intraprotein proton transfer

The crystal structures of cytochrome c oxidase from both bovine and Paracoccus denitrificans reveal two putative proton input channels that connect the heme-copper center, where dioxygen is reduced, to the internal aqueous phase. In this work we have examined the role of these two channels, looking at the effects of site-directed mutations of residues observed in each of the channels of the cytochrome c oxidase from Rhodobacter sphaeroides. A photoelectric technique was used to monitor the time-resolved electrogenic proton transfer steps associated with the photo-induced reduction of the ferryl-oxo form of heme a3 (Fe4+ = O2−) to the oxidized form (Fe3+OH−). This redox step requires the delivery of a “chemical” H+ to protonate the reduced oxygen atom and is also coupled to proton pumping. It is found that mutations in the K channel (K362M and T359A) have virtually no effect on the ferryl-oxo-to-oxidized (F-to-Ox) transition, although steady-state turnover is severely limited. In contrast, electrogenic proton transfer at this step is strongly suppressed by mutations in the D channel. The results strongly suggest that the functional roles of the two channels are not the separate delivery of chemical or pumped protons, as proposed recently [Iwata, S., Ostermeier, C., Ludwig, B. & Michel, H. (1995) Nature (London) 376, 660–669]. The D channel is likely to be involved in the uptake of both “chemical” and “pumped” protons in the F-to-Ox transition, whereas the K channel is probably idle at this partial reaction and is likely to be used for loading the enzyme with protons at some earlier steps of the catalytic cycle. This conclusion agrees with different redox states of heme a3 in the K362M and E286Q mutants under aerobic steady-state turnover conditions.

Suppression of tumor necrosis factor-induced cell death by inhibitor of apoptosis c-IAP2 is under NF-κB control

Members of the NF-κB/Rel and inhibitor of apoptosis (IAP) protein families have been implicated in signal transduction programs that prevent cell death elicited by the cytokine tumor necrosis factor α (TNF). Although NF-κB appears to stimulate the expression of specific protective genes, neither the identities of these genes nor the precise role of IAP proteins in this anti-apoptotic process are known. We demonstrate here that NF-κB is required for TNF-mediated induction of the gene encoding human c-IAP2. When overexpressed in mammalian cells, c-IAP2 activates NF-κB and suppresses TNF cytotoxicity. Both of these c-IAP2 activities are blocked in vivo by coexpressing a dominant form of IκB that is resistant to TNF-induced degradation. In contrast to wild-type c-IAP2, a mutant lacking the C-terminal RING domain inhibits NF-κB induction by TNF and enhances TNF killing. These findings suggest that c-IAP2 is critically involved in TNF signaling and exerts positive feedback control on NF-κB via an IκB targeting mechanism. Functional coupling of NF-κB and c-IAP2 during the TNF response may provide a signal amplification loop that promotes cell survival rather than death.

A model of ocular dominance column development by competition for trophic factor

Recent experimental evidence has shown that application of certain neurotrophic factors (NTs) to the developing primary visual cortex prevents the development of ocular dominance (OD) columns. One interpretation of this result is that afferents from the lateral geniculate nucleus compete for postsynaptic trophic factor in an activity-dependent manner. Application of excess trophic factor eliminates this competition, thereby preventing OD column formation. We present a model of OD column development, incorporating Hebbian synaptic modification and activity-driven competition for NT, which accounts for both normal OD column development as well as the prevention of that development when competition is removed. In the “control” situation, when available NT is below a critical amount, OD columns form normally. These columns form without weight normalization procedures and in the presence of positive inter-eye correlations. In the “experimental” case, OD column development is prevented in a local neighborhood in which excess NT has been added. Our model proposes a biologically plausible mechanism for competition between neural populations that is motivated by several pieces of experimental data, thereby accounting for both normal and experimentally perturbed conditions.

The mechanism of proton pumping by cytochrome c oxidase

Cytochrome c oxidase catalyzes the reduction of oxygen to water that is accompanied by pumping of four protons across the mitochondrial or bacterial membrane. Triggered by the results of recent x-ray crystallographic analyses, published data concerning the coupling of individual electron transfer steps to proton pumping are reanalyzed: Conversion of the conventional oxoferryl intermediate F to the fully oxidized form O is connected to pumping of only one proton. Most likely one proton is already pumped during the double reduction of O, and only three protons during conversion of the “peroxy” forms P to O via the oxoferryl form F. Based on the available structural, spectroscopic, and mutagenesis data, a detailed mechanistic model, carefully considering electrostatic interactions, is presented. In this model, each of the four reductions of heme a during the catalytic cycle is coupled to the uptake of one proton via the D-pathway. These protons, but never more than two, are temporarily stored in the regions of the heme a and a3 propionates and are driven to the outside (“pumped”) by electrostatic repulsion from protons entering the active site during turnover. The first proton is pumped by uptake of one proton via the K-pathway during reduction, the second and third proton during the P → F transition when the D-pathway and the active site become directly connected, and the fourth one upon conversion of F to O. Atomic structures are assigned to each intermediate including F′ with an alternative route to O.