Molecular and Phenotypic Characterization of Nannizzia (Arthrodermataceae)

Mycopathologia - Phylogenetic studies of the family Arthrodermataceae have revealed seven monophyletic dermatophyte clades representing the genera Trichophyton, Epidermophyton, Nannizzia,...     

Organic acids and ethanol inhibit the oxidation of methane by mire methanotrophs

Aerobic methane (CH(4) ) oxidation reduces the emission of CH(4) from mires and is regulated by various environmental factors. Organic acids and alcohols are intermediates of the anaerobic degradation of organic matter or are released by plant roots. Methanotrophs isolated from mires utilize these compounds preferentially to CH(4) . Thus, the effect of organic acids and ethanol on CH(4) oxidation by methanotrophs of a mire was evaluated. Slurries of mire soil oxidized supplemental CH(4) down to subatmospheric concentrations. The dominant pmoA and mmoX genotypes were affiliated with sequences from Methylocystis species capable of utilization of acetate and atmospheric CH(4) . Soil slurries supplemented with acetate, propionate or ethanol had reduced CH(4) oxidation rates compared with unsupplemented or glucose-supplemented controls. Expression of Methylocystis-affiliated pmoA decreased when CH(4) consumption decreased in response to acetate and was enhanced after acetate was consumed, at which time the consumption of CH(4) reached control levels. The inhibition of methanotroph activity might have been due to either toxicity of organic compounds or their preferred utilization. CH(4) oxidation was reduced at 5 and 0.5 mM of supplemental organic compounds. Acetate concentrations may exceed 3 mM in the investigated mire. Thus, the oxidation of CH(4) might decrease in microzones where organic acids occur.     

High-resolution proxies for wood density variations in Terminalia superba

Background and Aims

Density is a crucial variable in forest and wood science and is evaluated by a multitude of methods. Direct gravimetric methods are mostly destructive and time-consuming. Therefore, faster and semi- to non-destructive indirect methods have been developed.

Methods

Profiles of wood density variations with a resolution of approx. 50 µm were derived from one-dimensional resistance drillings, two-dimensional neutron scans, and three-dimensional neutron and X-ray scans. All methods were applied on Terminalia superba Engl. & Diels, an African pioneer species which sometimes exhibits a brown heart (limba noir).

Key Results

The use of X-ray tomography combined with a reference material permitted direct estimates of wood density. These X-ray-derived densities overestimated gravimetrically determined densities non-significantly and showed high correlation (linear regression, R² = 0·995). When comparing X-ray densities with the attenuation coefficients of neutron scans and the amplitude of drilling resistance, a significant linear relation was found with the neutron attenuation coefficient (R² = 0·986) yet a weak relation with drilling resistance (R² = 0·243). When density patterns are compared, all three methods are capable of revealing the same trends. Differences are mainly due to the orientation of tree rings and the different characteristics of the indirect methods.

Conclusions

High-resolution X-ray computed tomography is a promising technique for research on wood cores and will be explored further on other temperate and tropical species. Further study on limba noir is necessary to reveal the causes of density variations and to determine how resistance drillings can be further refined.     

The temporal structure of feeding behavior

Meals have long been considered relevant units of feeding behavior. Large data sets of feeding behavior of cattle, pigs, chickens, ducks, turkeys, dolphins, and rats were analyzed with the aims of 1) describing the temporal structure of feeding behavior and 2) developing appropriate methods for estimating meal criteria. Longer (between-meal) intervals were never distributed as the negative exponential assumed by traditional methods, such as log-survivorship analysis, but as a skewed Gaussian, which can be (almost) normalized by log-transformation of interval lengths. Log-transformation can also normalize frequency distributions of within-meal intervals. Meal criteria, i.e., the longest interval considered to occur within meals, can be estimated after fitting models consisting of Gaussian functions alone or of one Weibull and one or more Gaussian functions to the distribution of log-transformed interval lengths. Nonuniform data sets may require disaggregation before this can be achieved. Observations from all species were in conflict with assumptions of random behavior that underlie traditional methods for criteria estimation. Instead, the observed structure of feeding behavior is consistent with 1) a decrease in satiety associated with an increase in the probability of animals starting a meal with time since the last meal and 2) an increase in satiation associated with an increase in the probability of animals ending a meal with the amount of food already consumed. The novel methodology proposed here will avoid biased conclusions from analyses of feeding behavior associated with previous methods and, as demonstrated, can be applied across a range of species to address questions relevant to the control of food intake.     

Structure-based lead identification of ATP-competitive MK2 inhibitors

MK2 kinase is a promising drug discovery target for the treatment of inflammatory diseases. Here, we describe the discovery of novel MK2 inhibitors using X-ray crystallography and structure-based drug design. The lead has in vivo efficacy in a short-term preclinical model.     

Animal orientation strategies for movement in flows

For organisms that fly or swim, movement results from the combined effects of the moving medium - air or water - and the organism's own locomotion. For larger organisms, propulsion contributes significantly to progress but the flow usually still provides significant opposition or assistance, or produces lateral displacement ('drift'). Animals show a range of responses to flows, depending on the direction of the flow relative to their preferred direction, the speed of the flow relative to their own self-propelled speed, the incidence of flows in different directions and the proportion of the journey remaining. We here present a classification of responses based on the direction of the resulting movement relative to flow and preferred direction, which is applicable to a range of taxa and environments. The responses adopted in particular circumstances are related to the organisms' locomotory and sensory capacities and the environmental cues available. Advances in biologging technologies and particle tracking models are now providing a wealth of data, which often demonstrate a striking level of convergence in the strategies that very different animals living in very different environments employ when moving in a flow.     

The Ia.2 epitope defines a subset of lipid raft-resident MHC class II molecules crucial to effective antigen presentation

Previous work established that binding of the 11-5.2 anti-I-A(k) mAb, which recognizes the Ia.2 epitope on I-A(k) class II molecules, elicits MHC class II signaling, whereas binding of two other anti-I-A(k) mAbs that recognize the Ia.17 epitope fail to elicit signaling. Using a biochemical approach, we establish that the Ia.2 epitope recognized by the widely used 11-5.2 mAb defines a subset of cell surface I-A(k) molecules predominantly found within membrane lipid rafts. Functional studies demonstrate that the Ia.2-bearing subset of I-A(k) class II molecules is critically necessary for effective B cell-T cell interactions, especially at low Ag doses, a finding consistent with published studies on the role of raft-resident class II molecules in CD4 T cell activation. Interestingly, B cells expressing recombinant I-A(k) class II molecules possessing a β-chain-tethered hen egg lysosome peptide lack the Ia.2 epitope and fail to partition into lipid rafts. Moreover, cells expressing Ia.2(-) tethered peptide-class II molecules are severely impaired in their ability to present both tethered peptide or peptide derived from exogenous Ag to CD4 T cells. These results establish the Ia.2 epitope as defining a lipid raft-resident MHC class II conformer vital to the initiation of MHC class II-restricted B cell-T cell interactions.     

Alphacoronavirus transmissible gastroenteritis virus nsp1 protein suppresses protein translation in mammalian cells and in cell-free HeLa cell extracts but not in rabbit reticulocyte lysate

The nsp1 protein of transmissible gastroenteritis virus (TGEV), an alphacoronavirus, efficiently suppressed protein synthesis in mammalian cells. Unlike the nsp1 protein of severe acute respiratory syndrome coronavirus, a betacoronavirus, the TGEV nsp1 protein was unable to bind 40S ribosomal subunits or promote host mRNA degradation. TGEV nsp1 also suppressed protein translation in cell-free HeLa cell extract; however, it did not affect translation in rabbit reticulocyte lysate (RRL). Our data suggested that HeLa cell extracts and cultured host cells, but not RRL, contain a host factor(s) that is essential for TGEV nsp1-induced translational suppression.