Distinct mechanisms of Drosophila CRYPTOCHROME-mediated light-evoked membrane depolarization and in vivo clock resetting.

Drosophila CRYPTOCHROME (dCRY) mediates electrophysiological depolarization and circadian clock resetting in response to blue or ultraviolet (UV) light. These light-evoked biological responses operate at different timescales and possibly through different mechanisms. Whether electron transfer down a conserved chain of tryptophan residues underlies biological responses following dCRY light activation has been controversial. To examine these issues in in vivo and in ex vivo whole-brain preparations, we generated transgenic flies expressing tryptophan mutant dCRYs in the conserved electron transfer chain and then measured neuronal electrophysiological phototransduction and behavioral responses to light. Electrophysiological-evoked potential analysis shows that dCRY mediates UV and blue-light-evoked depolarizations that are long lasting, persisting for nearly a minute. Surprisingly, dCRY appears to mediate red-light-evoked depolarization in wild-type flies, absent in both cry-null flies, and following acute treatment with the flavin-specific inhibitor diphenyleneiodonium in wild-type flies. This suggests a previously unsuspected functional signaling role for a neutral semiquinone flavin state (FADH•) for dCRY. The W420 tryptophan residue located closest to the FAD-dCRY interaction site is critical for blue- and UV-light-evoked electrophysiological responses, while other tryptophan residues within electron transfer distance to W420 do not appear to be required for light-evoked electrophysiological responses. Mutation of the dCRY tryptophan residue W342, more distant from the FAD interaction site, mimics the cry-null behavioral light response to constant light exposure. These data indicate that light-evoked dCRY electrical depolarization and clock resetting are mediated by distinct mechanisms

The Burden of Cognitive Impairment in Patients With End-Stage Renal Disease and Impact on Dialysis Modality Choice

IntroductionKidney disease is associated with significant cognitive dysfunction. Subjective reports of cognitive ability have not been studied extensively in chronic kidney disease. We investigated the association between objective and subjective cognitive functions in predialysis patients and their association with self-care dialysis modality choice.MethodsCross-sectional data from the Barriers to Successful Implementation of Care in Home Haemodialysis study were used for the study of cognition in 220 predialysis patients. The data were used to ascertain the demographics, clinical, laboratory, and neuropsychometric variables. The latter includes Trail Making Tests (TMT) parts A and B, Modified Mini Mental State Examination, and metacognition questionnaire for subjective assessment of one’s cognitive ability. The outcome variable was fully assisted and self-care dialysis modality choice.ResultsWithin the study cohort, 90 patients chose fully assisted hemodialysis and 114 patients chose self-care dialysis. The median Modified Mini Mental State Examination, TMT part A, and TMT part B scores were greater for the assisted versus the self-care group. Metamemory was not significantly different between groups, but the metaconcentration score was significantly worse in the group choosing assisted dialysis. Higher (i.e., better) metaconcentration scores were significantly associated with the self-care modality choice in the univariate and hierarchical regression analyses. Adjusted and unadjusted analyses showed a significant association between perceived concentration and TMT part B scores (P < 0.01). With every 1.6-minute increase in TMT part B score, there was a 1-unit reduction in metaconcentration score, and the latter was associated with 20% lower odds of choosing self-care dialysis over a fully assisted dialysis modality.DiscussionPatients’ self-perception of cognitive ability is a significant predictor of self-care dialysis modality choice. Subjective report of “metaconcentration” is also strongly associated with poorer outcome on the TMT part B

Fano resonances in a three-terminal nanodevice

The electron transport through a quantum sphere with three one-dimensional wires attached to it is investigated. An explicit form for the transmission coefficient as a function of the electron energy is found from the first principles. The asymmetric Fano resonances are detected in transmission of the system. The collapse of the resonances is shown to appear under certain conditions. A two-terminal nanodevice with an additional gate lead is studied using the developed approach. Additional resonances and minima of transmission are indicated in the device.Comment: 11 pages, 5 figures, 2 equations are added, misprints in 5 equations are removed, published in Journal of Physics: Condensed Matte

Prebiotic synthesis of cysteine peptides that catalyze peptide ligation in neutral water

Peptide biosynthesis is performed by ribosomes and several other classes of enzymes, but a simple chemical synthesis may have created the first peptides at the origins of life. a-Aminonitriles—prebiotic a–amino acid precursors—are generally produced by Strecker reactions. However, cysteine’s aminothiol is incompatible with nitriles. Consequently, cysteine nitrile is not stable, and cysteine has been proposed to be a product of evolution, not prebiotic chemistry. We now report a high-yielding, prebiotic synthesis of cysteine peptides. Our biomimetic pathway converts serine to cysteine by nitrile-activated dehydroalanine synthesis. We also demonstrate that N-acylcysteines catalyze peptide ligation, directly coupling kinetically stable—but energy-rich—a-amidonitriles to proteinogenic amines. This rare example of selective and efficient organocatalysis in water implicates cysteine as both catalyst and precursor in prebiotic peptide synthesis

Snake orbits and related magnetic edge states

We study the electron motion near magnetic field steps at which the strength and/or sign of the magnetic field changes. The energy spectrum for such systems is found and the electron states (bound and scattered) are compared with their corresponding classical paths. Several classical properties as the velocity parallel to the edge, the oscillation frequency perpendicular to the edge and the extent of the states are compared with their quantum mechanical counterpart. A class of magnetic edge states is found which do not have a classical counterpart.Comment: 8 pages, 10 figure

Mattrygghet i Europa: en kartlegging av kritiske matpraksiser og kulturelle forskjeller i Frankrike, Norge, Portugal, Romania og Storbritannia

How is food handled in safe and unsafe ways from retail to fork in European households? This is the overall research question raised in this report. The aim of this report is to contribute to an in-depth, detailed, empirical and nuanced analysis of how food is handled in everyday life in five European countries: France, Norway, Portugal, Romania and the UK. The first chapters (Part 1) describe the food cultural difference and food safety variation between the five countries, theories of practices that underpin the study and the transdisciplinary methods employed for studying shopping, transportation, storage and cooking a meal with chicken and raw vegetables in 75 European households. The first empirical chapters (Part 2) introduce the households in this study (chapter 2.1), discuss the everyday food life the households (chapter 2.2) and describe food anxieties and experiences with foodborne illnesses (chapter 2.3). Part 3 concentrates on food procuring and organising practices in the households and includes three empirical discussions of shopping (chapter 3.1), transportation (chapter 3.2) and storage (chapter 3.3). Part 4 discusses food preparation and comprises five chapters discussing the order of cooking (chapter 4.1), chicken preparation (chapter 4.2), vegetable preparation (chapter 4.3), determining doneness (chapter 4.4) and washing hands (chapter 4.5). Finally, Part 5 discusses the main findings in the report and suggests further research steps.info:eu-repo/semantics/publishedVersio

Prebiotic Catalytic Peptide Ligation Yields Proteinogenic Peptides by Intramolecular Amide Catalyzed Hydrolysis Facilitating Regioselective Lysine Ligation in Neutral Water

The prebiotic origin of catalyst-controlled peptide synthesis is fundamental to understanding the emergence of life. Building on our recent discovery that thiols catalyze the ligation of amino acids, amides, and peptides with amidonitriles in neutral water, we demonstrate the outcome of ligation depends on pH and that high pKa primary thiols are the ideal catalysts. While the most rapid thiol catalyzed peptide ligation occurs at pH 8.5-9, the most selective peptide ligation, that tolerates all proteinogenic side chains, occurs at pH 7. We have also identified the highly selective mechanism by which the intermediate peptidyl amidines undergo hydrolysis to α-peptides while demonstrating that the hydrolysis of amidines with nonproteinogenic structures, such as β- and γ-peptides, displays poor selectivity. Notably, this discovery enables the highly α-selective protecting-group-free ligation of lysine peptides at neutral pH while leaving the functional ε-amine side chain intact

Relationships between speed, change of direction and jump performance with cricket specific speed tests in male academy cricketers

Objectives: The aim of this study was to investigate the relationships between general speed and change of direction speed and‘cricket specific’ speed tests and the relationships between jump performance and speed and change of direction ability in male academy cricketers. Design and Methods: Sixteen academy male cricketers (age: 17 ± 0.7 years; height: 176.9 ± 6.2 cm; mass: 72.2 ± 13.2 kg) performed tests of 20 m sprint, 505 change of direction (COD) on both left and right legs, “quick single” with bat (WB) (17.68m), running-a-two WB, running-a-three WB, countermovement jump (CMJ), and drop jump (DJ). Results: Intra-class correlation coefficients (ICC’s) revealed high within-session reliability for all tests (ICC ≥ 0.92; p ≤ 0.001),except 0-5 m (ICC = 0.642; p ≤ 0.001) and 0-10 m (ICC = 0.708; p ≤ 0.001) tests. General speed tests showed strong relationships to ‘cricket specific’ speed tests (20 m sprint - running-a-two; r = 0.951; p ≤ 0.01; 20 m sprint - running-a-three; r = 0.937; p ≤ 0.01; ‘quick single’; r = 0.951; p ≤ 0.01). Strong relationships were also observed between the 505 right foot COD times and all cricket specific tests (r = 0.909- 0.934; p ≤ 0.01). CMJ height showed the strongest correlations with: 20 m (r = -0.668;p ≤ 0.01); 505 left (r = -0.789; p ≤ 0.01); 505 right (r = -0.807; p ≤ 0.01); “quick single” WB (r = -0.739; p ≤ 0.01); running-a two WB (r = -0.742; p ≤ 0.01); running-a-three (WB) (r = -0.733; p ≤ 0.01). Conclusions: The findings suggest that general speed and COD tests are highly appropriate to assess cricket specific qualities in youth cricketers

Two-dimensional electron gas in a linearly varying magnetic field: Quantization of the electron and current density

Published versio