AN AUTORADIOGRAPHIC AND HISTOCHEMICAL LOCALIZATION OF SULFATED POLYSACCHARIDES IN EUCHEUMA NUDUM (RHODOPHYTA)1

The predominant sulfated polysaccharide, ?-carrageenan, was localized in the middle lamella of epidermal, cortical and medullary cells of Eucheumanudum J. Agardh. Autoradiographic studies with ³⁵SO₄= indicated that the label was first incorporated in the inner wall and ultimately deposited in the middle lamella of all cells, and in an outer wall layer of the epidermal cells. There was no evidence for cytoplasmic incorporation of the label. The middle lamella stained with alcian blue, was γ-metachromatic with toluidina blue O and bound diaminobenzidine-osmium tetroxide. This region was also positive with periodic acid-Schiff's (PAS) ragent, possibly demonstrating cellulose and/or a nonsulfated precursor of ?-carrageenan. A proposed model for extracellular sulfation includes production and secretion of a nonsulfated polygalactan and sulfotransferase enzyme(s) by the golgi apparatus and endoplasmic reticulum, respectively. Free sulfate in the wall would be bound to the precursor polysaccharide, with much of the resulting carrageenan migrating to the middle lamella facilitating mutual cell growth.     

High-dose versus standard-dose vitamin D supplementation in older adults with COVID-19 (COVIT-TRIAL): A multicenter,open-label,randomized controlled superiority trial

BackgroundVitamin D supplementation has been proposed as a treatment for Coronavirus Disease 2019 (COVID-19) based on experimental data and data from small and uncontrolled observational studies. The COvid19 and VITamin d TRIAL (COVIT-TRIAL) study was conducted to test whether a single oral high dose of cholecalciferol (vitamin D3) administered within 72 hours after the diagnosis of COVID-19 improves, compared to standard-dose cholecalciferol, the 14-day overall survival among at-risk older adults infected with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2).Methods and findingsThis multicenter, randomized, controlled, open-label, superiority trial involved collaboration of 9 medical centers in France. Patients admitted to the hospital units or living in nursing homes adjacent to the investigator centers were eligible if they were ≥65 years, had SARS-CoV-2 infection of less than 3 days, and at least 1 COVID-19 worsening risk factor (among age ≥75 years, SpO2 ≤94%, or PaO₂/FiO₂ ≤300 mm Hg). Main noninclusion criteria were organ failure requiring ICU, SpO2 ≤92% despite 5 L/min oxygen, life expectancy <3 months, vitamin D supplementation >800 IU/day during the preceding month, and contraindications to vitamin D supplements. Eligible and consenting patients were randomly allocated to either a single oral high-dose (400,000 IU) or standard-dose (50,000 IU) cholecalciferol administered under medical supervision within 72 hours after the diagnosis of COVID-19. Participants and local study staff were not masked to the allocated treatment, but the Steering Committee and the Data and Safety Monitoring Board were masked to the randomization group and outcome data during the trial. The primary outcome was 14-day overall mortality. Between April 15 and December 17, 2020, of 1,207 patients who were assessed for eligibility in the COVIT-TRIAL study, 254 met eligibility criteria and formed the intention-to-treat population. The median age was 88 (IQR, 82 to 92) years, and 148 patients (58%) were women. Overall, 8 (6%) of 127 patients allocated to high-dose cholecalciferol, and 14 (11%) of 127 patients allocated to standard-dose cholecalciferol died within 14 days (adjusted hazard ratio = 0.39 [95% confidence interval [CI], 0.16 to 0.99], P = 0.049, after controlling for randomization strata [i.e., age, oxygen requirement, hospitalization, use of antibiotics, anti-infective drugs, and/or corticosteroids] and baseline imbalances in important prognostic factors [i.e., sex, ongoing cancers, profuse diarrhea, and delirium at baseline]). The number needed to treat for one person to benefit (NNTB) was 21 [NNTB 9 to ∞ to number needed to treat for one person to harm (NNTH) 46]. Apparent benefits were also found on 14-day mortality due to COVID-19 (7 (6%) deaths in high-dose group and 14 (11%) deaths in standard-dose group; adjusted hazard ratio = 0.33 [95% CI, 0.12 to 0.86], P = 0.02). The protective effect of the single oral high-dose administration was not sustained at 28 days (19 (15%) deaths in high-dose group and 21 (17%) deaths in standard-dose group; adjusted hazard ratio = 0.70 [95% CI, 0.36 to 1.36], P = 0.29). High-dose cholecalciferol did not result in more frequent adverse effects compared to the standard dose. The open-label design and limited study power are the main limitations of the study.ConclusionsIn this randomized controlled trial (RCT), we observed that the early administration of high-dose versus standard-dose vitamin D3 to at-risk older patients with COVID-19 improved overall mortality at day 14. The effect was no longer observed after 28 days.Trial registrationClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT04344041","term_id":"NCT04344041"}}NCT04344041.

In a randomized trial, Cedric Annweiler and colleagues evaluate whether a single high dose of vitamin D3 improves survival among older adults in France with SARS-CoV-2 infection.     

Assessing the effect of complex ground types on ground‐dwelling arthropod movements with video monitoring: Dealing with concealed movements under a layer of plant residues

Understanding the effect of ground types on foraging movements of ground‐dwelling arthropods is a key step to managing their spatial distribution as required for successful conservation biological control. Indeed, fine movements at the centimeter scale can strongly influence the foraging ability of pest predators. However, because radio frequency identification or harmonic tracking techniques are not yet suitable for small species and video tracking focuses on uniform and light backgrounds, foraging movements have rarely been studied in relation to ground types. We present a method to track a ground‐dwelling arthropod (the earwig Euborellia caraibea) at night, walking on two contrasted ground types: bare soil and soil partly covered with a stratum of banana plant residues allowing individuals to hide periodically. The tracking of individuals within these ground types was achieved by infrared light, tagging individuals, video treatments, and semi‐automatic cleaning of trajectories. We tested different procedures to obtain segments with identical durations to quantify speeds and sinuosities. These procedures were characterized by the junction time gap between trajectory fragments, the rediscretization time of trajectories, and whether or not to use interpolation to fill in missing points in the trajectories. Earwigs exhibited significantly slower and more sinuous movements on soil with banana plant residues than on bare soil. Long time gaps for trajectory junction, extended rediscretization times, and interpolation were complementary means to integrate concealed movements in the trajectories. The highest slowdown in plant residues was detected when the procedure could account for longer periods under the residues. These results suggest that earwigs spent a significant amount of time concealed by the residues. Additionally, the residues strongly decreased the earwigs'' movement. Since the technical solutions presented in this study are inexpensive, easy to set up, and replicate, they represent valuable contributions to the emerging field of video monitoring.     

Lysosomal enzyme precursors in coated vesicles derived from the exocytic and endocytic pathways

The molecular forms of two lysosomal enzymes, cathepsin C and cathepsin D, have been examined in lysosomes and coated vesicles (CVs) of rat liver. In addition, the relative proportion of these lysosomal enzymes residing in functionally distinct CV subpopulations was quantitated. CVs contained newly synthesized precursor forms of the enzymes in contrast to lysosomes where only the mature forms were detected. Exocytic and endocytic CV subpopulations were prepared by two completely different protocols. One procedure, a density shift method, uses cholinesterase to alter the density of CVs derived from exocytic or endocytic pathways. The other relies on electrophoretic heterogeneity to accomplish the CV subfractionation. Subpopulations of CVs prepared by either procedure showed similar results, when examined for their relative proportion of cathepsin C and cathepsin D precursors. Within the starting CV preparation, exocytic CVs contained approximately 80-90% of the total steady-state levels of these enzymes while the level in the endocytic population was approximately 10-13%. The implications of these findings are discussed with regard to lysosome trafficking.     

治疗性克隆与体细胞重编程：殊途同归

治疗性克隆和体细胞重编程是制备患者特异性自体干细胞的两种不同策略,近期已取得了重大的研究进展.治疗性克隆是通过体细胞核移植后形成克隆囊胚进而获得胚胎干细胞,体细胞重编程则是将特异性转录因子导入到体细胞核中而建立诱导性多潜能干细胞(induced pluripotent stem cells,iPS细胞).两者在方法学路径、技术难题、伦理争议等方面各不相同,但在应用研究层面上都涉及到干细胞的定向诱导分化、细胞移植治疗等相同的问题.本文总结了这两种生物技术的研究进展及其异同点.     

Modelling pollination services across agricultural landscapes

Background and Aims

Crop pollination by bees and other animals is an essential ecosystem service. Ensuring the maintenance of the service requires a full understanding of the contributions of landscape elements to pollinator populations and crop pollination. Here, the first quantitative model that predicts pollinator abundance on a landscape is described and tested.

Methods

Using information on pollinator nesting resources, floral resources and foraging distances, the model predicts the relative abundance of pollinators within nesting habitats. From these nesting areas, it then predicts relative abundances of pollinators on the farms requiring pollination services. Model outputs are compared with data from coffee in Costa Rica, watermelon and sunflower in California and watermelon in New Jersey–Pennsylvania (NJPA).

Key Results

Results from Costa Rica and California, comparing field estimates of pollinator abundance, richness or services with model estimates, are encouraging, explaining up to 80 % of variance among farms. However, the model did not predict observed pollinator abundances on NJPA, so continued model improvement and testing are necessary. The inability of the model to predict pollinator abundances in the NJPA landscape may be due to not accounting for fine-scale floral and nesting resources within the landscapes surrounding farms, rather than the logic of our model.

Conclusions

The importance of fine-scale resources for pollinator service delivery was supported by sensitivity analyses indicating that the model''s predictions depend largely on estimates of nesting and floral resources within crops. Despite the need for more research at the finer-scale, the approach fills an important gap by providing quantitative and mechanistic model from which to evaluate policy decisions and develop land-use plans that promote pollination conservation and service delivery.Key words: Agriculture, bees, ecosystem services, landscape ecology, model, land use, pollinators     

Molecular Diversity of New Thermococcales Isolates from a Single Area of Hydrothermal Deep-Sea Vents as Revealed by Randomly Amplified Polymorphic DNA Fingerprinting and 16S rRNA Gene Sequence Analysis

Members of the Thermococcales are anaerobic Archaea belonging to the kingdom Euryarchaea that are studied in many laboratories as model organisms for hyperthermophiles. We describe here a molecular analysis of 86 new Thermococcales isolates collected from six different chimneys of a single hydrothermal field located in the 13°N 104°W segment of the East Pacific ridge at a depth of 2,330 m. These isolates were sorted by randomly amplified polymorphic DNA (RAPD) fingerprinting into nine groups, and nine unique RAPD profiles were obtained. One RAPD group corresponds to new isolates of Thermococcus hydrothermalis, whereas all other groups and isolates with unique profiles are different from the 22 reference strains included in this study. Analysis of 16S rRNA gene sequences of representatives of each RAPD group and unique profiles showed that one group corresponds to Pyrococcus strains, whereas all the other isolates are Thermococcus strains. We estimated that our collection may contain at least 11 new species. These putative species, isolated from a single area of hydrothermal deep-sea vents, are dispersed in the 16S rRNA tree among the reference strains previously isolated from diverse hot environments (terrestrial, shallow water, hydrothermal vents) located around the world, suggesting that there is a high degree of dispersal of Thermococcales. About one-half of our isolates contain extrachromosomal elements that could be used to search for novel replication proteins and to develop genetic tools for hyperthermophiles.     

Regulation of cell adhesion to collagen via β1 integrins is dependent on interactions of filamin A with vimentin and protein kinase C epsilon

Cell adhesion and spreading on collagen, which are essential processes for development and wound healing in mammals, are mediated by β1 integrins and the actin and intermediate filament cytoskeletons. The mechanisms by which these separate cytoskeletal systems interact to regulate β1 integrins and cell spreading are poorly defined. We previously reported that the actin cross-linking protein filamin A binds the intermediate filament protein vimentin and that these two proteins co-regulate cell spreading. Here we used deletional mutants of filamin A to define filamin A-vimentin interactions and the subsequent phosphorylation and re-distribution of vimentin during cell spreading on collagen. Imaging of fixed and live cell preparations showed that phosphorylated vimentin is translocated to the cell membrane during spreading. Knockdown of filamin A inhibited cell spreading and the phosphorylation and re-distribution of vimentin. Knockdown of filamin A and/or vimentin reduced the cell surface expression and activation of β1 integrins, as indicated by immunoblotting of plasma membrane-associated proteins and shear force assays. In vitro pull-down assays using filamin A mutants showed that both vimentin and protein kinase C? bind to repeats 1-8 of filamin A. Reconstitution of filamin-A-deficient cells with full-length filamin A or filamin A repeats 1-8 restored cell spreading, vimentin phosphorylation, and the cell surface expression of β1 integrins. We conclude that the binding of filamin A to vimentin and protein kinase Cε is an essential regulatory step for the trafficking and activation of β1 integrins and cell spreading on collagen.