Kinesin expands and stabilizes the GDP-microtubule lattice

Kinesin-1 is a nanoscale molecular motor that walks towards the fast-growing (plus) ends of microtubules, hauling molecular cargo to specific reaction sites in cells. Kinesin-driven transport is central to the self-organization of eukaryotic cells and shows great promise as a tool for nano-engineering1. Recent work hints that kinesin may also play a role in modulating the stability of its microtubule track, both in vitro2,3 and in vivo4, but the results are conflicting5,6,7 and the mechanisms are unclear. Here, we report a new dimension to the kinesin–microtubule interaction, whereby strong-binding state (adenosine triphosphate (ATP)-bound and apo) kinesin-1 motor domains inhibit the shrinkage of guanosine diphosphate (GDP) microtubules by up to two orders of magnitude and expand their lattice spacing by ~1.6%. Our data reveal an unexpected mechanism by which the mechanochemical cycles of kinesin and tubulin interlock, and so allow motile kinesins to influence the structure, stability and mechanics of their microtubule track

\u27Candidatus Xenohaliotis californiensis\u27, a newly described pathogen of abalone, Haliotis spp., along the west coast of North America

Withering syndrome is a fatal disease of wild and cultured abalone. Haliotis spp., that inhabit the west coast of North America. The aetiological agent of withering syndrome has recently been identified as a member of the family Rickettsiaceae in the order Rickettsiales. Using a combination of morphological, serological, life history and genomic (16S rDNA) characterization. we have identified this bacterium as a unique taxon and propose the provisional status of \u27Candidatus Xenohaliotis californiensis\u27, The Gram-negative. obligate intracellular pleomorphic bacterium is found within membrane-bound vacuoles in the cytoplasm of abalone gastrointestinal epithelial cells. The bacterium is not cultivable on synthetic media or in fish cell lines (e.g. CHSE-214) and may be controlled by tetracyclines (oxytetracycline) but not by chloramphenicol, clarithromycin or sarafloxicin. Phylogenetic analysis based on the 16S rDNA of \u27Candidatus Xenohaliotis californiensis\u27 places it in the alpha-subclass of the class Proteobacteria but not to the four recognized subtaxa of the alpha-Proteobacteria (alpha-1, alpha-2, alpha-3 and alpha-4). The bacterium can be detected in tissue squashes stained with propidium iodide, microscopic examination of stained tissue sections, PCR or in situ hybridization. \u27Candidatus Xenohaliotis californiensis\u27 can be differentiated from other closely related alpha-Proteobacteria by its unique 16S rDNA sequence

Estimating fine-root production by tree species and understorey functional groups in two contrasting peatland forests

Background and aims Estimation of root-mediated carbon fluxes in forested peatlands is needed for understanding ecosystem functioning and supporting greenhouse gas inventories. Here, we aim to determine the optimal methodology for utilizing ingrowth cores in estimating annual fine-root production (FRP) and its vertical distribution in trees, shrubs and herbs. Methods We used 3-year data obtained with modified ingrowth core method and tested two calculation methods: 'ingrowth-dividing' and `ingrowth-subtracting'. Results The ingrowth-dividing method combined with a 2-year incubation of ingrowth cores can be used for the 'best estimate' of FRP. The FRP in the nutrient-rich fen forest (561 g m(-2)) was more than twice that in the nutrient-poor bog forest (244 g m(-2)). Most FRP occurred in the top 20-cm layer (76-82 %). Tree FRP accounted for 71 % of total FRP in the bog and 94 % in the fen forests, respectively, following the aboveground vegetation patterns; however, in fen forest the proportions of spruce and birch in FRP were higher than their proportions in stand basal area. Conclusions Our methodology may be used to study peatland FRP patterns more widely and will reduce the volume of labour-intensive work, but will benefit from verification with other methods, as is the case in all in situ FRP studies.Peer reviewe

Does the age of fine root carbon indicate the age of fine roots in boreal forests?

To test the reliability of the radiocarbon method for determining root age, we analyzed fine roots (originating from the years 1985 to 1993) from ingrowth cores with known maximum root age (1 to 6 years old). For this purpose, three Scots pine (Pinus sylvestris L.) stands were selected from boreal forests in Finland. We analyzed root 14C age by the radiocarbon method and compared it with the above-mentioned known maximum fine root age. In general, ages determined by the two methods (root 14C age and ingrowth core root maximum age) were in agreement with each other for roots of small diameter (<0.5mm). By contrast, in most of the samples of fine roots of larger diameter (1.5-2mm), the 14C age of root samples of 1987-89 exceeded the ingrowth core root maximum age by 1-10 years. This shows that these roots had received a large amount of older stored carbon from unknown sources in addition to atmospheric CO2 directly from photosynthesis. We conclude that the 14C signature of fine roots, especially those of larger diameter, may not always be indicative of root age, and that further studies are needed concerning the extent of possible root uptake of older carbon and its residence time in roots. Keywords: fine root age, Pinus sylvestris, radiocarbon, root carbon, ingrowth cores, tree ringPeer reviewe

Fine-root turnover rates of European forests revisited: an analysis of data from sequential coring and ingrowth cores

Background and Aims Forest trees directly contribute to carbon cycling in forest soils through the turnover of their fine roots. In this study we aimed to calculate root turnover rates of common European forest tree species and to compare them with most frequently published values. Methods We compiled available European data and applied various turnover rate calculation methods to the resulting database. We used Decision Matrix and Maximum-Minimum formula as suggested in the literature. Results Mean turnover rates obtained by the combination of sequential coring and Decision Matrix were 0.86 yr−1 for Fagus sylvatica and 0.88 yr−1 for Picea abies when maximum biomass data were used for the calculation, and 1.11 yr−1 for both species when mean biomass data were used. Using mean biomass rather than maximum resulted in about 30 % higher values of root turnover. Using the Decision Matrix to calculate turnover rate doubled the rates when compared to the Maximum-Minimum formula. The Decision Matrix, however, makes use of more input information than the Maximum-Minimum formula. Conclusions We propose that calculations using the Decision Matrix with mean biomass give the most reliable estimates of root turnover rates in European forests and should preferentially be used in models and C reporting

Broken replication forks trigger heritable DNA breaks in the terminus of a circular chromosome

<p><u>(A) Circular map of the <i>E</i>. <i>coli</i> chromosome</u>: <i>oriC</i>, <i>dif</i> and <i>terD</i> to <i>terB</i> sites are indicated. Numbers refer to the chromosome coordinates (in kb) of MG1655. (<u>B) Linear map of the terminus region:</u> chromosome coordinates are shown increasing from left to right, as in the marker frequency panels (see Figure 1C for example), therefore in the opposite direction to the circular map. In addition to <i>dif</i> and <i>ter</i> sites, the positions of the <i>parS</i>_pMT1 sites used for microscopy experiments are indicated. (<u>C) MFA analysis of terminus DNA loss in the <i>recB</i> mutant</u>: sequence read frequencies of exponential phase cells normalized to the total number of reads were calculated for each strain. Ratios of normalized reads in isogenic wild-type and <i>recB</i> mutant are plotted against chromosomal coordinates (in kb). The profile ratio of the terminus region is enlarged and the profile of the corresponding entire chromosomes is shown in inset. Original normalized profiles used to calculate ratios are shown in <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1007256#pgen.1007256.s005" target="_blank">S1 Fig</a>. The position of <i>dif</i> is indicated by a red arrow. The <i>ter</i> sites that arrest clockwise forks (<i>terC</i>, <i>terB</i>, green arrow) and counter-clockwise forks (<i>terA</i>, <i>terD</i>, blue arrow) are shown. <u>(D) Schematic representation of focus loss in the <i>recB</i> mutant:</u> Time-lapse microscopy experiments showed that loss of a focus in the <i>recB</i> mutant occurs concomitantly with cell division in one of two daughter cells, and that the cell that keeps the focus then generates a focus-less cell at each generation. The percentage of initial events was calculated as the percentage of cell divisions that generate a focus-less cell, not counting the following generations. In this schematic representation, two initial events occurred (generations #2 and #7) out of 9 generations, and focus loss at generation #2 is heritable. Panels shown in this figure were previously published in [<a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1007256#pgen.1007256.ref019" target="_blank">19</a>] and are reproduced here to introduce the phenomenon.</p

Modern Clinical Research on LSD

All modern clinical studies using the classic hallucinogen lysergic acid diethylamide (LSD) in healthy subjects or patients in the last 25 years are reviewed herein. There were five recent studies in healthy participants and one in patients. In a controlled setting, LSD acutely induced bliss, audiovisual synesthesia, altered meaning of perceptions, derealization, depersonalization, and mystical experiences. These subjective effects of LSD were mediated by the 5-HT2A receptor. LSD increased feelings of closeness to others, openness, trust, and suggestibility. LSD impaired the recognition of sad and fearful faces, reduced left amygdala reactivity to fearful faces, and enhanced emotional empathy. LSD increased the emotional response to music and the meaning of music. LSD acutely produced deficits in sensorimotor gating, similar to observations in schizophrenia. LSD had weak autonomic stimulant effects and elevated plasma cortisol, prolactin, and oxytocin levels. Resting-state functional magnetic resonance studies showed that LSD acutely reduced the integrity of functional brain networks and increased connectivity between networks that normally are more dissociated. LSD increased functional thalamocortical connectivity and functional connectivity of the primary visual cortex with other brain areas. The latter effect was correlated with subjective hallucinations. LSD acutely induced global increases in brain entropy that were associated with greater trait openness 14 days later. In patients with anxiety associated with life-threatening disease, anxiety was reduced for 2 months after two doses of LSD. In medical settings, no complications of LSD administration were observed. These data should contribute to further investigations of the therapeutic potential of LSD in psychiatry

Quantifying head acceleration exposure via instrumented mouthguards (iMG): a validity and feasibility study protocol to inform iMG suitability for the TaCKLE project

Instrumented mouthguards (iMGs) have the potential to quantify head acceleration exposures in sport. The Rugby Football League is looking to deploy iMGs to quantify head acceleration exposures as part of the Tackle and Contact Kinematics, Loads and Exposure (TaCKLE) project. iMGs and associated software platforms are novel, thus limited validation studies exist. The aim of this paper is to describe the methods that will determine the validity (ie, laboratory validation of kinematic measures and on-field validity) and feasibility (ie, player comfort and wearability and practitioner considerations) of available iMGs for quantifying head acceleration events in rugby league. Phase 1 will determine the reliability and validity of iMG kinematic measures (peak linear acceleration, peak rotational velocity, peak rotational acceleration), based on laboratory criterion standards. Players will have three-dimensional dental scans and be provided with available iMGs for phase 2 and phase 3. Phase 2 will determine the on-field validity of iMGs (ie, identifying true positive head acceleration events during a match). Phase 3 will evaluate player perceptions of fit (too loose, too tight, bulky, small/thin, held mouth open, held teeth apart, pain in jaw muscles, uneven bite), comfort (on lips, gum, tongue, teeth) and function (speech, swallowing, dry mouth). Phase 4 will evaluate the practical feasibility of iMGs, as determined by practitioners using the system usability scale (preparing iMG system and managing iMG data). The outcome will provide a systematic and robust assessment of a range of iMGs, which will help inform the suitability of each iMG system for the TaCKLE project

Stakeholder perceptions of a tackle law variation to reduce concussion incidence in community rugby union: A qualitative study

This study aimed to investigate the perceptions of key stakeholder groups, i.e. coaches, players, and referees, of a reduced maximum legal tackle height law variation trial in a collegiate amateur rugby competition. A pragmatic qualitative approach was used. Eighteen semi-structured interviews were performed. Thematic analysis was used to analyse the data. Three main law trial-related themes and four additional contextual themes were identified. The most important contextual factors include perceptions of resource scarcity of the implementation context, deficient concussion knowledge and lack of education among all stakeholder groups, tackle technique deficiencies, and an entrenched culture of a dismissive attitude towards serious injuries and non-disclosure of concussion by players. Real-world challenges such as inconsistent sanctioning during gameplay, multi-tackler tackles, and player fatigue underscore the gap between the theoretical knowledge of the law and the complex, dynamic nature of its execution. Furthermore, deeply ingrained issues like entrenched tackle techniques, the quality of coaching, and prevailing attitudes towards concussion compounded these challenges, indicating a need for a more comprehensive approach to bridge the divide between understanding and implementation. Despite these challenges, several participants felt the law variation was still more effective than the existing law; and that it created more awareness around concussion, while sending a clear message that player welfare is being taken seriously. Collectively these factors indicate the difficulty of addressing a complex problem such as concussion, with a law variation intervention in a challenging (resource-constrained) setting

Consensus on a video analysis framework of descriptors and definitions by the Rugby Union Video Analysis Consensus group

Using an expert consensus-based approach, a rugby union Video Analysis Consensus (RUVAC) group was formed to develop a framework for video analysis research in rugby union. The aim of the framework is to improve the consistency of video analysis work in rugby union and help enhance the overall quality of future research in the sport. To reach consensus, a systematic review and Delphi method study design was used. After a systematic search of the literature, 17 articles were used to develop the final framework that described and defined key actions and events in rugby union (rugby). Thereafter, a group of researchers and practitioners with experience and expertise in rugby video analysis formed the RUVAC group. Each member of the group examined the framework of descriptors and definitions and rated their level of agreement on a 5-point agreement Likert scale (1: strongly disagree; 2: disagree; 3: neitheragree or disagree; 4: agree; 5: strongly agree). The mean rating of agreement on the five-point scale (1: strongly disagree; 5: strongly agree) was 4.6 (4.3–4.9), 4.6 (4.4–4.9), 4.7 (4.5–4.9), 4.8 (4.6–5.0) and 4.8 (4.6–5.0) for the tackle, ruck, scrum, line-out and maul, respectively. The RUVAC group recommends using this consensus as the starting framework when conducting rugby video analysis research. Which variables to use (if not all) depends on the objectives of the study. Furthermore, the intention of this consensus is to help integrate video data with other data (eg, injury surveillance)