1,556 research outputs found
Observations of Colloidal Gold Labelled Platelet Microtubules: High Voltage Electron Microscopy and Low Voltage-High Resolution Scanning Electron Microscopy
18 nm colloidal gold-antitubulin and 4 nm colloidal gold-antitubulin were used to label microtubules in adherent, fully spread platelets. Both sizes of marker effectively labelled microtubules in the partially extracted platelets. However only the 4 nm gold penetrated the dense microfilament matrix of the inner filamentous zone so that portions of microtubules within this cytoskeletal zone could be tracked. The gold marker could be visualized well with 1 MeV high voltage transmission EM and with 5 kV or greater secondary imaging or 20 kV backscattered imaging of carbon only coated samples. 1 kV secondary imaging permitted high resolution imaging of the surface of tubules and the microfilaments with their respective associated material. Individual gold-antibody complexes were difficult to identify by shape alone due to the tendency of the antibody coats to blend together when in very close approximation and due to the presence of other molecules or molecular aggregates similar in size to the gold-antibody labels.
Microtubules were seen to wind in and out of the inner and outer filamentous zones as they encircled the granulomere. Some tubules were seen to dead end at the peripheral web. Numerous smaller microtubule loops were present principally in the outer filamentous zone and tubules could be followed as they went from the outer filamentous zone through the inner filamentous zone and into the granulomere
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Deliverable 6.1: Radio spectrum, traffic engineering and resource management
Interplay between Mitochondrial Protein Import and Respiratory Complexes Assembly in Neuronal Health and Degeneration
The fact that >99% of mitochondrial proteins are encoded by the nuclear genome and synthesised in the cytosol renders the process of mitochondrial protein import fundamental for normal organelle physiology. In addition to this, the nuclear genome comprises most of the proteins required for respiratory complex assembly and function. This means that without fully functional protein import, mitochondrial respiration will be defective, and the major cellular ATP source depleted. When mitochondrial protein import is impaired, a number of stress response pathways are activated in order to overcome the dysfunction and restore mitochondrial and cellular proteostasis. However, prolonged impaired mitochondrial protein import and subsequent defective respiratory chain function contributes to a number of diseases including primary mitochondrial diseases and neurodegeneration. This review focuses on how the processes of mitochondrial protein translocation and respiratory complex assembly and function are interlinked, how they are regulated, and their importance in health and disease
Mejora del comportamiento en la extrusión de pastas cerámicas de baja plasticidad.
Shaping by extrusion may be used for the manufacture of tiles, bricks, and also
refractory products. The three fundamental aspects that must be considered to achieve
ideal extrusion conditions are the nature of the material, particle size and Plastic
behaviour. Of these, obtaining a mass of adequate plasticity is essential during the
processing in order to prevent defects such as cracks, laminations or migrations of the
liquid phase [1]. Plastic behaviour depends on numerous factors [2]: size and shape of
the particle, mineralogical composition, presence of electrolytes, organic matter, etc.
With regard to traditional ceramics, as is the case of the manufacture of ceramic
tiles, clay materials are those with the necessary plasticity to carry out the extrusion
process. However, in the absence of clays with sufficient plasticity or when the
composition incorporates a high proportion of other non-plastic ingredients, the
extrusion operation may be seriously compromised, particularly for the manufacture of
large or complex tiles. In these cases it is necessary to add plasticizers or binders to
the pastes to achieve rheological behaviour and plasticity enabling correct processing
of the composition [3].
In this report the influence of different additives in different proportions on the
plasticity index of a ceramic composition was evaluated and the variation of the
plasticity index was related to the behaviour of the paste during extrusion.El conformado por extrusión se puede utilizar para la fabricación de baldosas,
ladrillos, tejas o también productos refractarios. Los tres aspectos fundamentales que
se deben considerar para lograr unas condiciones de extrusión idóneas son la naturaleza
del material, el tamaño de partícula y el comportamiento plástico. De éstas, obtener
una masa de plasticidad adecuada es fundamental durante el procesado, para evitar la
aparición de defectos tales como grietas, laminaciones o migraciones de la fase líquida
[1]. El comportamiento plástico depende de numerosos factores [2]: tamaño y forma
de la partícula, composición mineralógica, presencia de electrolitos, materia orgánica,
etc.
En lo que concierne a las cerámicas tradicionales, como es el caso de la
fabricación de baldosas cerámicas, los materiales arcillosos son los que confieren la
plasticidad necesaria para llevar a cabo el proceso de extrusión. Sin embargo, cuando
no se dispone de arcillas con la plasticidad suficiente o cuando la composición incorpora
otros ingredientes no plásticos en elevada proporción, la operación de extrusión se
puede ver seriamente comprometida, sobre todo en la fabricación de baldosas de gran
formato o de geometría compleja. En estos casos es necesario añadir a las pastas
aditivos plastificantes o ligantes para conseguir un comportamiento reológico y
plasticidad que permitan un correcto procesado de la composición [3].
En este trabajo se evaluó la influencia de la incorporación de diferentes aditivos
en distintas proporciones sobre el índice de plasticidad de una composición cerámica y
se relacionó la variación del índice de plasticidad con el comportamiento de la pasta
durante la extrusión
Broad-scale genetic assessment of Southern Ground-Hornbills (Bucorvus leadbeateri) to inform population management.
The Southern Ground-hornbill (SGH) (Bucorvus leadbeateri) is considered an umbrella species for biodiversity conservation in savannah biomes since they require large territories and significant protection measures that help to conserve a wide range of biodiversity with similar savanna and grassland requirements. Declines of the species are attributed to low reproductive rates coupled with multiple anthropogenic threats, including secondary poisoning, and persecution. Little is known about connectivity and population structure of SGH populations in Africa, south of the equator. Knowledge of population differentiation is needed to ensure that targeted conservation management plans can be implemented to slow population declines and ensure survival of the species. To inform a long-term conservation strategy, we investigated the broad-scale population structure of Southern Ground-hornbill across their sub-equatorial range. Our study based on 16 microsatellite loci identified moderate variation (average of 5.889 alleles per locus and a mean observed heterozygosity of 0.546) similar to other long-lived avian species. In contrast, mitochondrial DNA sequences analysis identified low diversity (Hd = 0.3313, π = 0.0015). A Bayesian assignment approach, principal component analysis, analysis of molecular variance and phylogenetic analysis identified weak to moderate population structuring across long distances and mitochondrial data showed a shallow phylogeny. Restriction to long-distance dispersal was detected that could not be attributed to isolation by distance, suggesting that other factors, such as their dispersal biology, are shaping the observed genetic differentiation. Although our study does not support the designation of populations as independent conservation units, we advocate that population management should continue to follow the Precautionary Principle (mixing founders from the same range state, rather than allowing mixing of founders from the extremes of the range) until there is scientific certainty. Following further research, if no independent conservation units are detected, then the global captive population can contribute to reintroductions across the range. In the wild, populations at the edge of the species range may need additional management strategies and gene flow should be promoted between neighbouring populations
Mass spectrometry of B. subtilis CopZ: Cu(I)-binding and interactions with bacillithiol
CopZ from Bacillus subtilis is a well-studied member of the highly conserved family of Atx1-like copper chaperones. It was previously shown via solution and crystallographic studies to undergo Cu(I)-mediated dimerisation, where the CopZ dimer can bind between one and four Cu(I) ions. However, these studies could not provide information about the changing distribution of species at increasing Cu(I) levels. To address this, electrospray ionisation mass spectrometry using soft ionisation was applied to CopZ under native conditions. Data revealed folded, monomeric CopZ in apo- and Cu(I)-bound forms, along with Cu(I)-bound dimeric forms of CopZ at higher Cu(I) loading. Cu4(CopZ)2 was the major dimeric species at loadings >1 Cu(I)/CopZ, indicating the cooperative formation of the tetranuclear Cu(I)-bound species. As the principal low molecular weight thiol in B. subtilis, bacillithiol (BSH) may play a role in copper homeostasis. Mass spectrometry showed that increasing BSH led to a reduction in Cu(I)-bound dimeric forms, and the formation of S-bacillithiolated apo-CopZ and BSH adducts of Cu(I)-bound forms of CopZ, where BSH likely acts as a Cu(I) ligand. These data, along with the high affinity of BSH for Cu(I), determined here to be β2(BSH) = ∼4 × 1017 M−2, are consistent with a role for BSH alongside CopZ in buffering cellular Cu(I) levels. Here, mass spectrometry provides a high resolution overview of CopZ–Cu(I) speciation that cannot be obtained from less discriminating solution-phase methods, thus illustrating the potential for the wider application of this technique to studies of metal–protein interactions
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