Microbial mats of the Tswaing impact crater: results of a South African exobiology expedition and implications for the search for biological molecules on Mars

We describe microbial mats from the Tswaing impact crater in South Africa. The mats provide insights into the unique biological characteristics of impact craters and can help strategies for the search for biomolecules on Mars

Testing the limits of contextual constraint: interactions with word frequency and parafoveal preview during fluent reading

Contextual constraint is a key factor affecting a word's fixation duration and its likelihood of being fixated during reading. Previous research has generally demonstrated additive effects of predictability and frequency in fixation times. Studies examining the role of parafoveal preview have shown that greater preview benefit is obtained from more predictable and higher frequency words versus less predictable and lower frequency words. In two experiments, we investigated effects of target word predictability, frequency, and parafoveal preview. A 3 (Predictability: low, medium, high) × 2 (Frequency: low, high) design was used with Preview (valid, invalid) manipulated between experiments. With valid previews, we found main effects of Predictability and Frequency in both fixation time and probability measures, including an interaction in early fixation measures. With invalid preview, we again found main effects of Predictability and Frequency in fixation times, but no evidence of an interaction. Fixation probability showed a weak Predictability effect and Predictability-Frequency interaction. Predictability interacted with Preview in early fixation time and probability measures. Our findings suggest that high levels of contextual constraint exert an early influence during lexical processing in reading. Results are discussed in terms of models of language processing and eye movement control

Early EEG correlates of word frequency and contextual predictability in reading

Previous research into written language comprehension has been equivocal as to whether word frequency and contextual predictability effects share an early time course of processing. Target word frequency (low, high) and its predictability from prior context (low, high) were manipulated across two-sentence passages. Context sentences were presented in full, followed by word-by-word presentation (300 ms SOA) of target sentences. ERPs were analysed across left-to-right and anterior-to-posterior regions of interest within intervals from 50 to 550 ms post-stimulus. The onset of significant predictability effects (50–80 ms) preceded that of frequency (P1, 80–120 ms), while both main effects were generally sustained through the N400 (350–550 ms). Critically, the frequency-predictability interaction became significant in the P1 and was sustained through the N400, although the specific configuration of effects differed across components. The pattern of findings supports an early, chronometric locus of contextual predictability in recognising words during reading

A tool for subjective and interactive visual data exploration

We present SIDE, a tool for Subjective and Interactive Visual Data Exploration, which lets users explore high dimensional data via subjectively informative 2D data visualizations. Many existing visual analytics tools are either restricted to specific problems and domains or they aim to find visualizations that align with user’s belief about the data. In contrast, our generic tool computes data visualizations that are surprising given a user’s current understanding of the data. The user’s belief state is represented as a set of projection tiles. Hence, this user-awareness offers users an efficient way to interactively explore yet-unknown features of complex high dimensional datasets

Flexible delivery of Er:YAG radiation at 2.94 µm with negative curvature silica glass fibers:a new solution for minimally invasive surgical procedures

We present the delivery of high energy microsecond pulses through a hollow-core negative-curvature fiber at 2.94 µm. The energy densities delivered far exceed those required for biological tissue manipulation and are of the order of 2300 J/cm(2). Tissue ablation was demonstrated on hard and soft tissue in dry and aqueous conditions with no detrimental effects to the fiber or catastrophic damage to the end facets. The energy is guided in a well confined single mode allowing for a small and controllable focused spot delivered flexibly to the point of operation. Hence, a mechanically and chemically robust alternative to the existing Er:YAG delivery systems is proposed which paves the way for new routes for minimally invasive surgical laser procedures

V-ATPase expression during development of Artemia franciscana embryos: Potential role for proton gradients in anoxia signaling

Under anoxia, Artemia franciscana embryos downregulate metabolic processes and approach an ametabolic state. Entrance into this quiescent state is accompanied by a profound acidification of the intracellular space, and more than two decades of research now clearly demonstrates that this acidification is critical to metabolic downregulation in anoxic embryos. However, the proximal mechanisms responsible for the pH shift remain largely unidentified. Here, we report evidence demonstrating expression of the V-ATPase in encysted embryos and present an argument for its involvement in the intracellular acidification induced by anoxia. We identified a single B-subunit cDNA sharing the greatest degree of sequence similarity with \u27generalist-type\u27 homologues from mammals (brain-type) and invertebrates. Quantitative analysis of B-subunit mRNA demonstrates differential expression throughout early development, and western blot analyses confirm the expression of at least six V-ATPase subunits in both heavy membranes and microsomal vesicles. The critical need for proton pumping during the anoxia-tolerant stage of development is demonstrated by incubation with the V-ATPase inhibitor bafilomycin A1, which halts embryonic development. Importantly, net proton flux from V-ATPase-acidified compartments to the surrounding cytoplasm is likely under anoxia and may significantly contribute to the enigmatic acidification critical to quiescence

Cryopreservation of lipid bilayers by LEA proteins from Artemia franciscana and trehalose

© 2016 Elsevier Inc. The capacity of Late Embryogenesis Abundant (LEA) proteins and trehalose to protect liposomes against freezing-induced damage was examined by measuring the leakage of 5(6)-carboxyfluorescein (CF). Liposomes were prepared to simulate the lipid compositions of the inner leaflet of the plasma membrane, outer mitochondrial membrane (OMM), and inner mitochondrial membrane (IMM). Two recombinant LEA proteins belonging to Group 3 (AfrLEA2 and AfrLEA3m) were expressed and purified from embryos of Artemia franciscana. Only OMM-like liposomes were significantly protected by AfrLEA2 and AfrLEA3m against freeze-thaw damage; at the highest protein:lipid mass ratio tested, leakage of CF was 56.3% of control with AfrLEA3m and 29.3% with AfrLEA2. By comparison, trehalose provided protection to all compositional types. The greatest stabilization during freezing occurred when trehalose was present on both sides of the bilayer. When mitochondria isolated from rat liver were freeze-thawed in trehalose solution, the OMM remained intact based on the absence of increased oxygen consumption when cytochrome c was added during oxidative phosphorylation (OXPHOS). Respiratory control ratios (OXPHOS/LEAK) were depressed by only 30% after freeze-thawing in trehalose compared to non-frozen controls, which indicated some retention of OXPHOS capacity by the IMM. Trehalose then was loaded into the matrix (0.24 μmol/mg mitochondrial protein) by transient opening of the permeability transition pore, a procedure optimized for retention of OMM integrity. Surprisingly, respiratory control ratios were not improved after freeze-thawing with external plus matrix trehalose, when compared to external trehalose alone. This result could perhaps be explained by insufficient accumulation of matrix trehalose