Identification of eight novel coagulation factor XIII subunit A mutations: implied consequences for structure and function

Severe hereditary coagulation factor XIII deficiency is a rare homozygous bleeding disorder affecting one person in every two million individuals. In contrast, heterozygous factor XIII deficiency is more common, but usually not associated with severe hemorrhage such as intracranial bleeding or hemarthrosis. In most cases, the disease is caused by F13A gene mutations. Causative mutations associated with the F13B gene are rarer.

Recent advances into understanding some aspects of the structure and function of mammalian and avian lungs

Recent findings are reported about certain aspects of the structure and function of the mammalian and avian lungs that include (a) the architecture of the air capillaries (ACs) and the blood capillaries (BCs); (b) the pulmonary blood capillary circulatory dynamics; (c) the adaptive molecular, cellular, biochemical, compositional, and developmental characteristics of the surfactant system; (d) the mechanisms of the translocation of fine and ultrafine particles across the airway epithelial barrier; and (e) the particle-cell interactions in the pulmonary airways. In the lung of the Muscovy duck Cairina moschata, at least, the ACs are rotund structures that are interconnected by narrow cylindrical sections, while the BCs comprise segments that are almost as long as they are wide. In contrast to the mammalian pulmonary BCs, which are highly compliant, those of birds practically behave like rigid tubes. Diving pressure has been a very powerful directional selection force that has influenced phenotypic changes in surfactant composition and function in lungs of marine mammals. After nanosized particulates are deposited on the respiratory tract of healthy human subjects, some reach organs such as the brain with potentially serious health implications. Finally, in the mammalian lung, dendritic cells of the pulmonary airways are powerful agents in engulfing deposited particles, and in birds, macrophages and erythrocytes are ardent phagocytizing cellular agents. The morphology of the lung that allows it to perform different functions-including gas exchange, ventilation of the lung by being compliant, defense, and secretion of important pharmacological factors-is reflected in its "compromise design."

Structure and function of CinD (YtjD) of Lactococcus lactis, a copper-induced nitroreductase involved in defense against oxidative stress

In Lactococcus lactis IL1403, 14 genes are under the control of the copper-inducible CopR repressor. This so-called CopR regulon encompasses the CopR regulator, two putative CPx-type copper ATPases, a copper chaperone, and 10 additional genes of unknown function. We addressed here the function of one of these genes, ytjD, which we renamed cinD (copper-induced nitroreductase). Copper, cadmium, and silver induced cinD in vivo, as shown by real-time quantitative PCR. A knockout mutant of cinD was more sensitive to oxidative stress exerted by 4-nitroquinoline-N-oxide and copper. Purified CinD is a flavoprotein and reduced 2,6-dichlorophenolindophenol and 4-nitroquinoline-N-oxide with k(cat) values of 27 and 11 s(-1), respectively, using NADH as a reductant. CinD also exhibited significant catalase activity in vitro. The X-ray structure of CinD was resolved at 1.35 A and resembles those of other nitroreductases. CinD is thus a nitroreductase which can protect L. lactis against oxidative stress that could be exerted by nitroaromatic compounds and copper.

Diversity of structure and function of alpha1alpha6beta3delta GABAA receptors: comparison with alpha1beta3delta and alpha6beta3delta receptors

delta subunit-containing gamma-aminobutyric acid, type A (GABA(A))receptors are expressed extrasynaptically and mediate tonic inhibition. In cerebellar granule cells, they often form receptors together with alpha(1) and/or alpha(6) subunits. We were interested in determining the architecture of receptors containing both subunits. We predefined the subunit arrangement of several different GABA(A) receptor pentamers by concatenation. These receptors composed of alpha(1), alpha(6), beta(3), and delta subunits were expressed in Xenopus oocytes. Currents elicited in response to GABA were determined in the presence and absence of 3alpha,21-dihydroxy-5alpha-pregnan-20-one (THDOC) or ethanol, or currents were elicited by 4,5,6,7-tetrahydroisoxazolo[5,4-c]-pyridin-3-ol (THIP). Several subunit configurations formed active channels. We therefore conclude that delta can assume multiple positions in a receptor pentamer made up of alpha(1), alpha(6), beta(3), and delta subunits. The different receptors differ in their functional properties. Functional expression of one receptor type was only evident in the combined presence of the neurosteroid THDOC with the channel agonist GABA. Most, but not all, receptors active with GABA/THDOC responded to THIP. None of the receptors was modulated by ethanol concentrations up to 30 mm. Several observations point to a preferred position of delta subunits between two alpha subunits in alpha(1)alpha(6)beta(3)delta receptors. This property is shared by alpha(1)beta(3)delta and alpha(6)beta(3)delta receptors, but there are differences in the additionally expressed isoforms.

Structure and function of the glucose PTS transporter from Escherichia coli

The glucose transporter IICB of the Escherichia coli phosphotransferase system (PTS) consists of a polytopic membrane domain (IIC) responsible for substrate transport and a hydrophilic C-terminal domain (IIB) responsible for substrate phosphorylation. We have overexpressed and purified a triple mutant of IIC (mut-IIC), which had recently been shown to be suitable for crystallization purposes. Mut-IIC was homodimeric as determined by blue native-PAGE and gel-filtration, and had an eyeglasses-like structure as shown by negative-stain transmission electron microscopy (TEM) and single particle analysis. Glucose binding and transport by mut-IIC, mut-IICB and wildtype-IICB were compared with scintillation proximity and in vivo transport assays. Binding was reduced and transport was impaired by the triple mutation. The scintillation proximity assay allowed determination of substrate binding, affinity and specificity of wildtype-IICB by a direct method. 2D crystallization of mut-IIC yielded highly-ordered tubular crystals and made possible the calculation of a projection structure at 12Å resolution by negative-stain TEM. Immunogold labeling TEM revealed the sidedness of the tubular crystals, and high-resolution atomic force microscopy the surface structure of mut-IIC. This work presents the structure of a glucose PTS transporter at the highest resolution achieved so far and sets the basis for future structural studies.

Effects of anticancer drug docetaxel on the structure and function of the rabbit olfactory mucosa

Docetaxel (DCT) is an anticancer drug which acts by disrupting microtubule dynamics in the highly mitotic cancer cells. Thus, this drug has a potential to affect function and organization of tissues exhibiting high cellular turnover. We investigated, in the rabbit, the effects of a single human equivalent dose (6.26mg/kg, i.v.) of DCT on the olfactory mucosa (OM) through light and electron microscopy, morphometry, Ki-67 immunostaining, TUNEL assay and the buried food test for olfactory sensitivity. On post-exposure days (PED) 5 and 10, there was disarrangement of the normal cell layering in the olfactory epithelium (OE), apoptotic death of cells of the OE, Bowman's glands and axon bundles, and the presence (including on PED 3) of blood vessels in the bundle cores. A decrease in bundle diameters, olfactory cell densities and cilia numbers, which was most significant on PED 10 (49.3%, 63.4% and 50%, respectively), was also evident. Surprisingly by PED 15, the OM regained normal morphology. Furthermore, olfactory sensitivity decreased progressively until PED 10 when olfaction was markedly impaired, and with recovery from the impairment by PED 15. These observations show that DCT transiently alters the structure and function of the OM suggesting a high regenerative potential for this tissue.

Ecosystem structure, function, and composition in rangelands are negatively affected by livestock grazing

Reports of positive or neutral effects of grazing on plant species richness have prompted calls for livestock grazing to be used as a tool for managing land for conservation. Grazing effects, however, are likely to vary among different response variables, types, and intensity of grazing, and across abiotic conditions. We aimed to examine how grazing affects ecosystem structure, function, and composition. We compiled a database of 7615 records reporting an effect of grazing by sheep and cattle on 278 biotic and abiotic response variables for published studies across Australia. Using these data, we derived three ecosystem measures based on structure, function, and composition, which were compared against six contrasts of grazing pressure, ranging from low to heavy, two different herbivores (sheep, cattle), and across three different climatic zones. Grazing reduced structure (by 35%), function (24%), and composition (10%). Structure and function (but not composition) declined more when grazed by sheep and cattle together than sheep alone. Grazing reduced plant biomass (40%), animal richness (15%), and plant and animal abundance, and plant and litter cover (25%), but had no effect on plant richness nor soil function. The negative effects of grazing on plant biomass, plant cover, and soil function were more pronounced in drier environments. Grazing effects on plant and animal richness and composition were constant, or even declined, with increasing aridity. Our study represents a comprehensive continental assessment of the implications of grazing for managing Australian rangelands. Grazing effects were largely negative, even at very low levels of grazing. Overall, our results suggest that livestock grazing in Australia is unlikely to produce positive outcomes for ecosystem structure, function, and composition or even as a blanket conservation tool unless reduction in specific response variables is an explicit management objective.

Snake venom C-type lectins interacting with platelet receptors. Structure-function relationships and effects on haemostasis

Snake venoms contain components that affect the prey either by neurotoxic or haemorrhagic effects. The latter category affect haemostasis either by inhibiting or activating platelets or coagulation factors. They fall into several types based upon structure and mode of action. A major class is the snake C-type lectins or C-type lectin-like family which shows a typical folding like that in classic C-type lectins such as the selectins and mannose-binding proteins. Those in snake venoms are mostly based on a heterodimeric structure with two subunits alpha and beta, which are often oligomerized to form larger molecules. Simple heterodimeric members of this family have been shown to inhibit platelet functions by binding to GPIb but others activate platelets via the same receptor. Some that act via GPIb do so by inducing von Willebrand factor to bind to it. Another series of snake C-type lectins activate platelets by binding to GPVI while yet another series uses the integrin alpha(2)beta(1) to affect platelet function. The structure of more and more of these C-type lectins have now been, and are being, determined, often together with their ligands, casting light on binding sites and mechanisms. In addition, it is relatively easy to model the structure of the C-type lectins if the primary structure is known. These studies have shown that these proteins are quite a complex group, often with more than one platelet receptor as ligand and although superficially some appear to act as inhibitors, in fact most function by inducing thrombocytopenia by various routes. The relationship between structure and function in this group of venom proteins will be discussed.

Na+ channel function, regulation, structure, trafficking and sequestration.

This paper is the second of a series of three reviews published in this issue resulting from the University of California Davis Cardiovascular Symposium 2014: Systems approach to understanding cardiac excitation-contraction coupling and arrhythmias: Na(+) channel and Na(+) transport. The goal of the symposium was to bring together experts in the field to discuss points of consensus and controversy on the topic of sodium in the heart. The present review focuses on Na(+) channel function and regulation, Na(+) channel structure and function, and Na(+) channel trafficking, sequestration and complexing.

Caspase-3-independent photoreceptor degeneration by N-methyl-N-nitrosourea (MNU) induces morphological and functional changes in the mouse retina

Retinal degeneration is followed by significant changes in the structure and function of photoreceptors in humans and several genetic animal models. However, it is not clear whether similar changes occur when the degeneration is induced pharmacologically. Therefore, our aim was to investigate the influence of retinotoxic N-methyl-N-nitrosourea (MNU) on the function, morphology and underlying molecular pathways of programmed cell death.

From Structure to Function: Characterization of Cu(I) Adducts in Leveler Additives by DFT Calculations

We present the first molecular model of the coordination complex formed by Cu(I) and imidazole-epichlorohydrin polymers. Our calculations show that the Cu(I) ion has linear coordination and the whole complex has neutral charge. Our model suggests salt couple pairing as the driving force for the formation of the surface-confined precipitation, which is crucial to obtain flat surfaces in industrial copper deposition processes, required for mass fabrication of state-of-the-art electronic and memory devices.