Perfect Narrowband Absorber Based on Patterned Graphene-Silica Multilayer Hyperbolic Metamaterials

Plasmonics - Graphene-based hyperbolic metamaterials are well known for their optical anisotropy, high absorption of electromagnetic radiation, and low energy loss. We proposed a novel multilayer...     

Effects of physical connection and genetic identity of neighbouring ramets on root-placement patterns in two clonal species

Root-placement patterns were examined in the clonal species Glechoma hederacea and Fragaria vesca when grown with different types of neighbours. Three different patterns were predicted as consequences of different types of interactions between roots: the avoidance pattern if root growth decreases in the presence of neighbouring roots; the intrusive pattern if root growth increases towards neighbouring roots; and the unresponsive pattern if root growth is unaffected by neighbouring roots. Experiments were conducted in which physical connection between ramets, and the genetic identity of neighbouring ramets, were manipulated. The patterns of distribution of entire root systems and elongation rates of individual roots were measured. Root systems and individual roots of G. hederacea avoided contact with roots of neighbouring ramets, irrespective of connection to the neighbour and its genetic or specific identity. In contrast, F. vesca roots grew equally towards and away from intraspecific ramet neighbours and their elongation was stimulated by contact with roots of G. hederacea ramets. These results demonstrate that root-placement patterns of plants grown with different types of neighbours vary between species, and suggest that factors additional to resource depletion could be involved in their development.     

Structural aspects of the functional activity of the cerebral cortex synapses in the early postresuscitation period

The numeral density of the revealed with the help of PTA-plane and twisted asymmetric and symmetric interneuronal contacts of the sensomotor brain cortex of rats after 6 minutes mechanical asphyxia has been studied. It was revealed that in 90 minutes and 6 hours the relative contacts of the concave synapses will be increased progressively. This reaction has the compensatory-adaptive character and ensures the restoration of the integrative activity of the brain during the early postresuscitation period.     

Characterisation of a Multi-ligand Binding Chemoreceptor CcmL (Tlp3) of Campylobacter jejuni

Campylobacter jejuni is the leading cause of human gastroenteritis worldwide with over 500 million cases annually. Chemotaxis and motility have been identified as important virulence factors associated with C. jejuni colonisation. Group A transducer-like proteins (Tlps) are responsible for sensing the external environment for bacterial movement to or away from a chemical gradient or stimulus. In this study, we have demonstrated Cj1564 (Tlp3) to be a multi-ligand binding chemoreceptor and report direct evidence supporting the involvement of Cj1564 (Tlp3) in the chemotaxis signalling pathway via small molecule arrays, surface plasmon and nuclear magnetic resonance (SPR and NMR) as well as chemotaxis assays of wild type and isogenic mutant strains. A modified nutrient depleted chemotaxis assay was further used to determine positive or negative chemotaxis with specific ligands. Here we demonstrate the ability of Cj1564 to interact with the chemoattractants isoleucine, purine, malic acid and fumaric acid and chemorepellents lysine, glucosamine, succinic acid, arginine and thiamine. An isogenic mutant of cj1564 was shown to have altered phenotypic characteristics of C. jejuni, including loss of curvature in bacterial cell shape, reduced chemotactic motility and an increase in both autoagglutination and biofilm formation. We demonstrate Cj1564 to have a role in invasion as in in vitro assays the tlp3 isogenic mutant has a reduced ability to adhere and invade a cultured epithelial cell line; interestingly however, colonisation ability of avian caeca appears to be unaltered. Additionally, protein-protein interaction studies revealed signal transduction initiation through the scaffolding proteins CheV and CheW in the chemotaxis sensory pathway. This is the first report characterising Cj1564 as a multi-ligand receptor for C. jejuni, we therefore, propose to name this receptor CcmL, Campylobacter chemoreceptor for multiple ligands. In conclusion, this study identifies a novel multifunctional role for the C. jejuni CcmL chemoreceptor and illustrates its involvement in the chemotaxis pathway and subsequent survival of this organism in the host.     

Foraging for space and avoidance of physical obstructions by plant roots: a comparative study of grasses from contrasting habitats

Physical obstructions that reduce space for root growth can profoundly affect plant performance. The aim of this study was to investigate the ability of roots to avoid obstructions and forage for usable space, and to reveal the mechanism involved. Eight grass species from four genera were examined. Each genus included species characteristic of habitats with high and low nutrient availability. The ability to limit root mass and to adjust morphology within substrate containing obstructions in the form of gravel was investigated. A treatment with activated carbon, which adsorbs organic compounds, was used to examine the possible involvement of root exudates in responses to obstructions. Only species characteristic of nutrient-poor habitats restricted placement of root mass in substrate containing obstructions, and this response disappeared in the presence of activated carbon. Root morphological responses to obstructions differed from those shown in response to nutrient-poor conditions or compacted soil. These results suggest that the ability to avoid obstructions is dependent on the sensitivity of roots to their own exudates accumulating in the vicinity of obstructions. This is similar to other behavioural responses in which cues or signals are used to adjust growth before stressful conditions are encountered.     

The "no reflow" phenomenon in the cerebral cortex in the early postischemic period

Experiments on white rats with clinical death due to blood loss were made to demonstrate the presence of the "no-reflow" focuses in the cerebral cortex in the first minutes of recirculation. The microcirculatory disturbances were functional in nature and were determined by the spasm of the small intracranial arteries, arterioles and precapillary sphincters.     

Effect of hypoxia on the structure of the presynaptic grid of the interneuronal contacts of the rat neocortex

Hypoxic effect (a 6 minute asphyxia) on the presynaptic grid structure and on the amount of synapses in the neocortex has been studied in white rats using the method of selective staining of synapses with phosphoric tungsten acid. Neurofilamentous formations of the presynaptic grid appeared to be most labile structures. Dense projections of the presynaptic grid are most sensitive to hypoxia: their height, distinctness of the frame, and the intensity degree of phosphoric tungsten acid staining decrease. The content of intermediate form contacts with low indistict dense projections increases with the increase in the number of light type changed synapses. The principle organization of the presynaptic grid does not change in the posthypoxic period: hexagonal division of dense projections and places of vesicular attachment are kept. The hypertrophy of the presynaptic grid is also kept during that process.     

Plastic restructuring of cerebral cortex synapses in the postischemic period

Using the technique for the cerebral tissue contrasting with phosphoric-tungsten acid, synaptic architectonics of the molecular layer of the rat sensomotor cortex has been studied for 30 days of recirculation after 5 minutes' stop of the systemic circulation resulted from an acute hemorrhage. Gradation of the synapses per groups is performed according to the height of compact projections of the presynaptic network. Dynamics of the synaptic compactness changes with different height is stated to differ essentially during the postischemic period. A conclusion is made that in reconstruction of the synaptic architectonics of the neocortex during the postischemic period a leading role belongs to the change of state of specialized paramembranous microfilamentous compact projections of the presynaptic network. They make a part of the neuronal cytoskeleton and are included into a single integral complex--the system of subcytoskeleton and are included into a single integral complex--the system of subsynaptic units.