RESUMEN
There is a growing requirement in computational neuroscience for tools that permit collaborative model building, model sharing, combining existing models into a larger system (multi-scale model integration), and are able to simulate models using a variety of simulation engines and hardware platforms. Layered XML model specification formats solve many of these problems, however they are difficult to write and visualise without tools. Here we describe a new graphical software tool, SpineCreator, which facilitates the creation and visualisation of layered models of point spiking neurons or rate coded neurons without requiring the need for programming. We demonstrate the tool through the reproduction and visualisation of published models and show simulation results using code generation interfaced directly into SpineCreator. As a unique application for the graphical creation of neural networks, SpineCreator represents an important step forward for neuronal modelling.
Asunto(s)
Modelos Neurológicos , Redes Neurales de la Computación , Neuronas/fisiología , Programas Informáticos , Ganglios Basales/fisiología , Simulación por Computador , Cuerpo Estriado/fisiología , Humanos , Interfaz Usuario-ComputadorRESUMEN
Reanalysis of the tryptic digests of soybean seed coat peroxidase (SBP) and its carboxyamidated peptide derivatives in the light of more complete sequence data has thrown light on the diglycosylated tryptic peptides, TP13 (Leu[183-205]Arg) and TP15 (Cys[208-231]Arg). Matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analyses indicate that although all potential sites carry some glycan substituents, not all sites are fully occupied. Tryptic glycopeptide TP13, carrying two N-glycosylation consensus sequons (Asn185 and Asn197), occurs mainly (85-90%) as the diglycosylated species, the remainder (10-15%) being monoglycosylated. In contrast, tryptic peptide TP15, also with two N-glycosylation sites (Asn211 and Asn216), is primarily monoglycosylated (approximately 90%), with the remainder (10%) being diglycosylated. No non-glycosylated TP13 or TP15 was observed. Some artifacts are noted in the reactions of N-terminal cysteine residues and aspartate/asparagines residues in glycopeptide TP15. Mapping the glycans onto the crystal structure of SBP shows that these are asymmetrically distributed on the molecule, occurring primarily on the substrate-channel face of the enzyme. In contrast, the glycans of HRP, isozyme c, are more uniformly distributed over the enzyme surface.
Asunto(s)
Glycine max/enzimología , Peroxidasas/química , Peroxidasas/metabolismo , Semillas/enzimología , Amidas/química , Amidas/metabolismo , Secuencia de Aminoácidos , Glicosilación , Datos de Secuencia Molecular , Peso Molecular , Fragmentos de Péptidos/química , Fragmentos de Péptidos/metabolismo , Polisacáridos/química , Tiazinas/síntesis químicaRESUMEN
Macromolecular crystals for X-ray diffraction studies are typically grown in vitro from pure and homogeneous samples; however, there are examples of protein crystals that have been identified in vivo. Recent developments in micro-crystallography techniques and the advent of X-ray free-electron lasers have allowed the determination of several protein structures from crystals grown in cellulo. Here, an atomic resolution (1.2â Å) crystal structure is reported of heterogeneous milk proteins grown inside a living organism in their functional niche. These in vivo-grown crystals were isolated from the midgut of an embryo within the only known viviparous cockroach, Diploptera punctata. The milk proteins crystallized in space group P1, and a structure was determined by anomalous dispersion from the native S atoms. The data revealed glycosylated proteins that adopt a lipocalin fold, bind lipids and organize to form a tightly packed crystalline lattice. A single crystal is estimated to contain more than three times the energy of an equivalent mass of dairy milk. This unique storage form of nourishment for developing embryos allows access to a constant supply of complete nutrients. Notably, the crystalline cockroach-milk proteins are highly heterogeneous with respect to amino-acid sequence, glycosylation and bound fatty-acid composition. These data present a unique example of protein heterogeneity within a single in vivo-grown crystal of a natural protein in its native environment at atomic resolution.
RESUMEN
Three cationic peroxidases have been detected in early, middle, and late corn steep water, with pI values of approximately 8.9, approximately 9.5, and >10.0. The major cationic corn steep water peroxidase (CSWP), with a pI >10, was purified 36400-fold with a 12% recovery from late steep water by a combination of acetone and ammonium sulfate precipitation and sequential chromatography on CM-cellulose, phenyl-Sepharose, and Sephadex G-75. The UV-vis spectrum of purified CSWP is typical of other plant class III peroxidases. The RZ (A(403)/A(280)) of CSWP was between 2.6 and 2.9. It is not glycosylated and exhibited an M(r) of 30662 +/- 7 by MALDI-TOF MS. The pH optimum of CSWP depends on the substrate, and it is active on 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid), guaiacol, ferulic acid, o-dianisidine, o-phenylenediamine, and pyrogallol but is not active on either syringaldazine or ascorbate. At 75 degrees C and pH 4.5, the enzyme has half-lives of 22.7 min (0 mM Ca(2+)) and 248 min (1 mM Ca(2+)). The enzyme is stable at room temperature (22-25 degrees C), losing <3% of the activity at pH 4.5 and <10% at pH 6.2 over 400 h in the presence of 1 mM Ca(2+).
Asunto(s)
Peroxidasas/aislamiento & purificación , Agua/química , Zea mays/enzimología , Aminoácidos/análisis , Carbohidratos/análisis , Cationes , Electroforesis en Gel de Poliacrilamida , Estabilidad de Enzimas , Concentración de Iones de Hidrógeno , Punto Isoeléctrico , Espectrometría de Masas , Peso Molecular , Peroxidasas/química , Peroxidasas/metabolismo , Especificidad por SustratoRESUMEN
Behavioural observations suggest that orang-utans are semi-solitary animals with females being philopatric and males roaming more widely in search of receptive partners, leading to the prediction that females are more closely related than males at any given site. In contrast, our study presents evidence for male and female philopatry in the orang-utan. We examined patterns of relatedness and parentage in a wild orang-utan population in Borneo using noninvasively collected DNA samples from animals observed to defecate, and microsatellite markers to assess dispersal and mating strategies. Surprisingly, resident females were equally as related to other resident females (mean r(xy) = 0.303) as resident males were to other resident males (mean r(xy) = 0.305). Moreover, resident females were more related to each other and to the resident males than they were to nonresident females, and resident males were more related to each other (and resident females) than they were to nonresident males. We assigned genetic mothers to 12 individuals in the population, while sires could be identified for eight. Both flanged males and unflanged males achieved paternity, similar to findings reported for Sumatran orang-utans.
Asunto(s)
Pongo pygmaeus/fisiología , Reproducción/fisiología , Animales , Femenino , Genotipo , Malasia , Masculino , Linaje , Pongo pygmaeus/genéticaRESUMEN
Risk management has become an everyday aspect of medicine. Pediatric emergency medicine training programs have a unique opportunity to educate fellows in the area of risk management, along with other areas of medical administration. This curriculum should provide a guideline for a logical and workable education in the basics of risk management.
Asunto(s)
Curriculum , Medicina de Emergencia/educación , Becas , Pediatría/educación , Gestión de Riesgos , Medicina de Emergencia/economía , Servicios de Información , Pediatría/economía , Estados UnidosRESUMEN
High-resolution scanning Hall probe microscopy has been used to image vortex configurations in very large periodic arrays of artificial pinning sites. Strong matching effects are seen at fields where either one or two vortices can sit at a site; with three vortices per site, however, no clear matching is observed. Matching effects have also been observed at several fractional multiples of the matching field, including 1/5, 1/4, 1/3, 1/2, and 3/4. These fractional values are characterized by striking domain structure and grain boundaries.
RESUMEN
Insulin-responsive aminopeptidase (IRAP) colocalizes with glucose transporter type 4 (GLUT4) in adipocytes and is recruited to the plasma membrane in response to insulin. Microinjection of peptides corresponding to the IRAP cytoplasmic domain sequences causes GLUT4 recruitment in adipocytes. Inhibitors of protein kinase C-zeta (PKC-zeta) abolish the insulin-induced GLUT4 recruitment in rat adipocytes. These findings suggest an interesting possibility that PKC-zeta may phosphorylate IRAP, playing a key role in GLUT4/IRAP recruitment. To test this possibility, here we studied the (32)P incorporation into IRAP catalyzed by PKC-zeta in insulin-stimulated cells. There was a small but significant (32)P incorporation into IRAP in rat adipocytes, which was partly abolished upon addition of a PKC-zeta pseudosubstrate, suggesting that PKC-zeta may be responsible in part for the IRAP phosphorylation in adipocytes. PKC-zeta also catalyzed the incorporation of (32)P not only into IRAP in GLUT4 vesicles isolated from rat adipocytes but also into the IRAP cytoplasmic domain inserts in glutathione S-transferase-fusion proteins, demonstrating direct IRAP phosphorylation by PKC-zeta. Reversed-phase HPLC, matrix-assisted laser desorption ionization mass spectrometry, and radiosequencing of the tryptic digests of the (32)P-labeled IRAP fusion proteins identified Ser-80 and Ser-91 as major phosphorylation sites. In GLUT4 vesicles, the (32)P incorporation into IRAP was exclusively localized at a 6.9-kDa tryptic fragment identified as IRAP(76-138) and the (32)P labeling at Ser-80 accounted for 80-90% of the total IRAP labeling, suggesting that Ser-80 is the major phosphorylation site in intact IRAP. These findings are consistent with the possibility that the IRAP cytoplasmic domain phosphorylation by PKC-zeta plays a key role in insulin-induced IRAP or GLUT4 recruitment in adipocytes.