The shell-forming proteome of Lottia gigantea reveals both deep conservations and lineage-specific novelties

19 pagesInternational audienceProteins that are occluded within the molluscan shell, the so-called shell matrix proteins (SMPs), are an assemblage of biomolecules attractive to study for several reasons. They increase the fracture resistance of the shell by several orders of magnitude, determine the polymorph of CaCO(3) deposited, and regulate crystal nucleation, growth initiation and termination. In addition, they are thought to control the shell microstructures. Understanding how these proteins have evolved is also likely to provide deep insight into events that supported the diversification and expansion of metazoan life during the Cambrian radiation 543 million years ago. Here, we present an analysis of SMPs isolated form the CaCO(3) shell of the limpet Lottia gigantea, a gastropod that constructs an aragonitic cross-lamellar shell. We identified 39 SMPs by combining proteomic analysis with genomic and transcriptomic database interrogations. Among these proteins are various low-complexity domain-containing proteins, enzymes such as peroxidases, carbonic anhydrases and chitinases, acidic calcium-binding proteins and protease inhibitors. This list is likely to contain the most abundant SMPs of the shell matrix. It reveals the presence of both highly conserved and lineage-specific biomineralizing proteins. This mosaic evolutionary pattern suggests that there may be an ancestral molluscan SMP set upon which different conchiferan lineages have elaborated to produce the diversity of shell microstructures we observe nowadays. DATABASE: Novel protein sequences reported in this article have been deposited in Swiss-Prot database under accession nos. B3A0P1-B3A0S4

Injectable Hydrogels Based on Pluronic/Water Systems Filled with Alginate Microparticles for Biomedical Applications

A (model) composite system for drug delivery was developed based on a thermoresponsive hydrogel loaded with microparticles. We used Pluronic F127 hydrogel as the continuous phase and alginate microparticles as the dispersed phase of this composite system. It is well known that Pluronic F127 forms a gel when added to water in an appropriate concentration and in a certain temperature range. Pluronic F127 hydrogel may be loaded with drug and injected, in its sol state, to act as a drug delivery system in physiological environment. A rheological characterization allowed the most appropriate concentration of Pluronic F127 (15.5 wt%) and appropriate alginate microparticles contents (5 and 10 wt%) to be determined. Methylene blue (MB) was used as model drug to perform drug release studies in MB loaded Pluronic hydrogel and in MB loaded alginate microparticles/Pluronic hydrogel composite system. The latter showed a significantly slower MB release than the former (10 times), suggesting its potential in the development of dual cargo release systems either for drug delivery or tissue engineering

Novel Weak Decays in Doubly Strange Systems

The strangeness-changing ($\Delta S = 1$) weak baryon-baryon interaction is studied through the nonmesonic weak decay of double-$\Lambda$ hypernuclei. Besides the usual nucleon-induced decay $\Lambda N \to N N$ we discuss novel hyperon-induced decay modes $\Lambda \Lambda \to \Lambda N$ and $\Lambda \Lambda \to \Sigma N$. These reactions provide unique access to the exotic $\Lambda \Lambda$K and $\Lambda \Sigma$K vertices which place new constraints on Chiral Pertubation Theory ($\chi$PT) in the weak SU(3) sector. Within a meson-exchange framework, we use the pseudoscalar $\pi,\eta,K$ octet for the long-range part while parametrizing the short-range part through the vector mesons $\rho, \omega, K^*$. Realistic baryon-baryon forces for the $S=0,-1$ and -2 sectors account for the strong interaction in the initial and final states. For $^6_{\Lambda \Lambda}$He the new hyperon-induced decay modes account for up to 4% of the total nonmesonic decay rate. Predictions are made for all possible nonmesonic decay modes.Comment: 19 pages, 2 ps figures, 9 table

Proton-neutron quadrupole interactions: an effective contribution to the pairing field

We point out that the proton-neutron energy contribution, for low multipoles (in particular for the quadrupole component), effectively renormalizes the strength of the pairing interaction acting amongst identical nucleons filling up a single-j or a set of degenerate many-j shells. We carry out the calculation in lowest-order perturbation theory. We perform a study of this correction in various mass regions. These results may have implications for the use of pairing theory in medium-heavy nuclei and for the study of pairing energy corrections to the liquid drop model when studying nuclear masses.Comment: 19 pages, TeX, 3 tables, 2 figures. Accepted in PR

5-ht inhibition of rat insulin 2 promoter cre recombinase transgene and proopiomelanocortin neuron excitability in the mouse arcuate nucleus

A number of anti-obesity agents have been developed that enhance hypothalamic 5-HT transmission. Various studies have demonstrated that arcuate neurons, which express proopiomelanocortin peptides (POMC neurons), and neuropeptide Y with agouti-related protein (NPY/AgRP) neurons, are components of the hypothalamic circuits responsible for energy homeostasis. An additional arcuate neuron population, rat insulin 2 promoter Cre recombinase transgene (RIPCre) neurons, has recently been implicated in hypothalamic melanocortin circuits involved in energy balance. It is currently unclear how 5-HT modifies neuron excitability in these local arcuate neuronal circuits. We show that 5-HT alters the excitability of the majority of mouse arcuate RIPCre neurons, by either hyperpolarization and inhibition or depolarization and excitation. RIPCre neurons sensitive to 5-HT, predominantly exhibit hyperpolarization and pharmacological studies indicate that inhibition of neuronal firing is likely to be through 5-HT1F receptors increasing current through a voltage-dependent potassium conductance. Indeed, 5-HT1F receptor immunoreactivity co-localizes with RIPCre green fluorescent protein expression. A minority population of POMC neurons also respond to 5-HT by hyperpolarization, and this appears to be mediated by the same receptor-channel mechanism. As neither POMC nor RIPCre neuronal populations display a common electrical response to 5-HT, this may indicate that sub-divisions of POMC and RIPCre neurons exist, perhaps serving different outputs

Valuing EQ-5D-Y-3L health states using a discrete choice experiment: do adult and adolescent preferences differ?

Background An important question in the valuation of children’s health is whether the preferences of younger individuals should be captured within value sets for measures that are aimed at them. This depends on whether younger individuals can complete valuation exercises and whether their preferences differ from those of adults. This study compared the preferences of adults and adolescents for EQ-5D-Y-3L health states using latent scale values elicited from a discrete choice experiment (DCE). Methods An online DCE survey, comprising 15 pairwise choices, was provided to samples of UK adults and adolescents (aged 11–17 y). Adults considered the health of a 10-year-old child, whereas adolescents considered their own health. Mixed logit models were estimated, and comparisons were made using relative attribute importance (RAI) scores and a pooled model. Results In total, 1000 adults and 1005 adolescents completed the survey. For both samples, level 3 in pain/discomfort was most important, and level 2 in self-care the least important, based on the relative magnitudes of coefficients. The RAI scores (normalized on self-care) indicated that adolescents gave less weight relative to adults to usual activities (1.18 v. 1.51; P < 0.05), pain/discomfort (1.77 v. 3.12; P < 0.01), and anxiety/depression (1.64 vs. 2.65; P < 0.01). The pooled model indicated evidence of differences between the two samples in both levels in pain/discomfort and anxiety/depression. Limitations The perspective of the DCE task differed between the 2 samples, and no data were collected to anchor the DCE data to generate value sets. Conclusions Adolescents could complete the DCE, and their preferences differed from those of adults taking a child perspective. It is important to consider whether their preferences should be incorporated into value sets

The Nucleon Spectral Function at Finite Temperature and the Onset of Superfluidity in Nuclear Matter

Nucleon selfenergies and spectral functions are calculated at the saturation density of symmetric nuclear matter at finite temperatures. In particular, the behaviour of these quantities at temperatures above and close to the critical temperature for the superfluid phase transition in nuclear matter is discussed. It is shown how the singularity in the thermodynamic T-matrix at the critical temperature for superfluidity (Thouless criterion) reflects in the selfenergy and correspondingly in the spectral function. The real part of the on-shell selfenergy (optical potential) shows an anomalous behaviour for momenta near the Fermi momentum and temperatures close to the critical temperature related to the pairing singularity in the imaginary part. For comparison the selfenergy derived from the K-matrix of Brueckner theory is also calculated. It is found, that there is no pairing singularity in the imaginary part of the selfenergy in this case, which is due to the neglect of hole-hole scattering in the K-matrix. From the selfenergy the spectral function and the occupation numbers for finite temperatures are calculated.Comment: LaTex, 23 pages, 21 PostScript figures included (uuencoded), uses prc.sty, aps.sty, revtex.sty, psfig.sty (last included

Super-Hubbard models and applications

We construct XX- and Hubbard- like models based on unitary superalgebras gl(N|M) generalising Shastry's and Maassarani's approach of the algebraic case. We introduce the R-matrix of the gl(N|M) XX model and that of the Hubbard model defined by coupling two independent XX models. In both cases, we show that the R-matrices satisfy the Yang--Baxter equation, we derive the corresponding local Hamiltonian in the transfer matrix formalism and we determine the symmetry of the Hamiltonian. Explicit examples are worked out. In the cases of the gl(1|2) and gl(2|2) Hubbard models, a perturbative calculation at two loops a la Klein and Seitz is performed.Comment: 26 page

Strangeness nuclear physics: a critical review on selected topics

Selected topics in strangeness nuclear physics are critically reviewed. This includes production, structure and weak decay of $\Lambda$--Hypernuclei, the $\bar K$ nuclear interaction and the possible existence of $\bar K$ bound states in nuclei. Perspectives for future studies on these issues are also outlined.Comment: 63 pages, 51 figures, accepted for publication on European Physical Journal

Alcance de la implementación del aprendizaje-servicio en cinco universidades jesuitas en Filipinas

L'aprenentatge servei és una forma d'educació vivencial en la qual els estudiants participen en activitats que aborden les necessitats humanes i de la comunitat juntament amb oportunitats estructurades dissenyades intencionadament per promoure l'aprenentatge i el desenvolupament dels estudiants. Les institucions d'educació superior filipines estan fent intents d'integrar l'aprenentatge servei als seus sistemes educatius. En aquest estudi qualitatiu actual, es va descriure el mecanisme d'aprenentatge servei en 5 institucions d'educació superior jesuïtes ubicades a diferents regions de les Filipines. La rúbrica d'autoavaluació de Furco per a la institucionalització de l'aprenentatge servei es va utilitzar com a eina d'avaluació. Els resultats van revelar que encara que les institucions estudiades eren totes universitats jesuïtes, cadascuna mostrava experiències úniques i diferents nivells d'implementació de l'aprenentatge servei. També variaven en el mecanisme o enfocament d'implementació. El que era evident entre les cinc institucions d'educació superior jesuïtes és el seu compromís compartit amb el servei i la justícia social com a part de la seva missió i identitat. La diferència en el nivell d'implementació entre les cinc institucions depèn de la longevitat de l'aprenentatge servei a la institució, el nombre de programes que utilitzen l'aprenentatge servei com a pedagogia, el compromís sostingut i la persistència dels administradors, el professorat i el personal no acadèmic.Service-learning is a form of experiential education in which students engage in activities that address human and community needs together with structured opportunities intentionally designed to promote student learning and development. Philippine Higher Education Institutions (HEIs) are making attempts to integrate service-learning in their educational systems. In this current qualitative study, the mechanism of service learning in 5 Jesuit higher education institutions located in different regions in the Philippines was described. Furco’s Self-Assessment Rubric for institutionalization of service learning as a framework was used as the evaluation tool. Results revealed that even if the institutions studied were all Jesuit universities, each one exhibited unique experiences and different levels of implementation of service learning. They also vary in the mechanism or approach of implementation. What was evident among the five Jesuit higher education institutions is their shared commitment towards service and social justice as part of their mission and identity. The difference in the level of implementation among the five HEIs depends on the longevity of the service learning in the institution, the number of programs that utilize service learning as a pedagogy, sustained commitment and persistence of the administrators, faculty and staff.El aprendizaje-servicio es una forma de educación experiencial en la que los estudiantes participan en actividades que abordan las necesidades humanas y de la comunidad junto con oportunidades estructuradas diseñadas intencionalmente para promover el aprendizaje y el desarrollo de los estudiantes. Las Instituciones de Educación Superior de Filipinas (IES) están intentando integrar el aprendizaje-servicio en sus sistemas educativos. En este estudio cualitativo, se describió el mecanismo de aprendizaje-servicio en 5 instituciones jesuitas de educación superior ubicadas en diferentes regiones de Filipinas. La rúbrica de autoevaluación de Furco para la institucionalización del aprendizaje-servicio se utilizó como herramienta de evaluación. Los resultados revelaron que incluso cuando las instituciones estudiadas eran todas universidades jesuitas, cada una exhibía experiencias únicas y diferentes niveles de implementación del aprendizaje-servicio. También varían en el mecanismo o enfoque de implementación. Lo que fue evidente entre las cinco instituciones jesuitas de educación superior fue su compromiso compartido con el servicio y la justicia social como parte de su misión e identidad. La diferencia en el nivel de implementación entre las cinco IES depende de la longevidad del aprendizaje-servicio en la institución, la cantidad de programas que utilizan el aprendizaje-servicio como pedagogía, el compromiso sostenido y la persistencia de los administradores, profesores y personal no académico