Stable and radiogenic isotope analyses on shark teeth from the Early to the Middle Permian (Sakmarian–Roadian) of the southwestern USA

δ¹⁸O_P values and ⁸⁷Sr/⁸⁶Sr ratios were determined on disarticulated xenacanthiform, hybodontid and ctenacanthid shark tooth material from several Early Permian (Sakmarian–Kungurian) continental bone beds of northern Texas and southern Oklahoma as well as from the marine Middle Permian (Roadian) of northern Arizona. The δ¹⁸O_P values derived from the teeth of bone beds are in the range of 17.6–23.5‰ VSMOW, and are mostly depleted in ¹⁸O by 0.5–5‰ relative to proposed coeval marine δ¹⁸O_P values. This indicates an adaptation to freshwater habitats on the Early Permian coastal plain by several sharks. Distinctly higher δ¹⁸O_P values from two bone beds are attributed to significant evaporative enrichment in ¹⁸O in flood plain ponds. ⁸⁷Sr/⁸⁶Sr ratios of around 0.71077 are notably more radiogenic than ⁸⁷Sr/⁸⁶Sr of contemporaneous seawater. In contrast, the isotopic composition of teeth from the marine Kaibab Formation is characterised by low δ¹⁸O_P values in the range of 13.4–15.6‰ VSMOW while ⁸⁷Sr/⁸⁶Sr ratios of around 0.70821 are closer to the Roadian seawater value. The distinctly depleted δ¹⁸O_P values cannot be readily explained by fluvially affected freshening in a nearshore marine environment, so a diagenetic alteration of the Kaibab material seems to be more likely, excluding it from further interpretation.     

Mapping FLS2 function to structure: LRRs, kinase and its working bits

The plasma membrane-localised FLAGELLIN SENSING 2 (FLS2) receptor is an important component of plant immunity against potentially pathogenic bacteria, acting to recognise the conserved flg22 peptide of flagellin. FLS2 shares the common structure of transmembrane receptor kinases with a receptor-like ectodomain composed of leucine-rich repeats (LRR) and an active intracellular kinase domain. Upon ligand binding, FLS2 dimerises with the regulatory LRR-receptor kinase BRI1-associated kinase 1, which in turn triggers downstream signalling cascades. Although lacking crystal structure data, recent advances have been made in our understanding of flg22 recognition based on structural and functional analyses of FLS2. These studies have revealed critical regions/residues of FLS2 and post-translational modifications that regulate the abundance and activity of this receptor. In this review, we present the current knowledge on the structural mechanism of the FLS2–flg22 interaction and subsequent receptor-mediated signalling.     

Unique monoclonal antibodies specifically bind surface structures on human fetal erythroid blood cells

Background

Continuing efforts in development of non-invasive prenatal genetic tests have focused on the isolation of fetal nucleated red blood cells (NRBCs) from maternal blood for decades. Because no fetal cell-specific antibody has been described so far, the present study focused on the development of monoclonal antibodies (mAbs) to antigens that are expressed exclusively on fetal NRBCs.Methods: Mice were immunized with fetal erythroid cell membranes and hybridomas screened for Abs using a multi-parameter fluorescence-activated cell sorting (FACS). Selected mAbs were evaluated by comparative FACS analysis involving Abs known to bind erythroid cell surface markers (CD71, CD36, CD34), antigen-i, galactose, or glycophorin-A (GPA). Specificity was further confirmed by extensive immunohistological and immunocytological analyses of NRBCs from umbilical cord blood and fetal and adult cells from liver, bone marrow, peripheral blood, and lymphoid tissues.Results: Screening of 690 hybridomas yielded three clones of which Abs from 4B8 and 4B9 clones demonstrated the desired specificity for a novel antigenic structure expressed on fetal erythroblast cell membranes. The antigenic structure identified is different from known surface markers (CD36, CD71, GPA, antigen-i, and galactose), and is not present on circulating adult erythroid cells, except for occasional detectability in adult bone marrow cells.Conclusions:The new mAbs specifically bind the same or highly overlapping epitopes of a surface antigen that is almost exclusively expressed on fetal erythroid cells. The high specificity of the mAbs should facilitate development of simple methods for reliable isolation of fetal NRBCs and their use in non-invasive prenatal diagnosis of fetal genetic status.     

Calponin 2 Acts As an Effector of Noncanonical Wnt-Mediated Cell Polarization during Neural Crest Cell Migration

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Highlights? Cnn2 is expressed in NCCs and required for their migration in frogs and chicks ? Cnn2 is inactivated by noncanonical Wnt signaling ? Loss of Cnn2 causes a switch from cortical actin to central stress fibers ? Cnn2 polarizes the actin cytoskeleton downstream of PCP     

Lichenicolous fungi show population subdivision by host species but do not share population history with their hosts

Lichenicolous fungi are a species-rich biological group growing on lichen thalli. Here, we analyze the genetic structure of the lichenicolous basidiomycete Tremella lobariacearum and three host species (Lobaria pulmonaria, Lobaria macaronesica, and Lobaria immixta) in Macaronesia. We used ordination and analysis of molecular variance to investigate the structuring of genetic variation, and a simulation test to investigate whether rDNA haplotypes of T. lobariacearum were significantly associated with host species. To investigate the evolutionary and demographic history of the lichenicolous fungus and its hosts, we used coalescent samplers to generate trees, and Bayesian skyline plots. We found that the hosts were most important in structuring populations of the lichenicolous species. Despite their wide geographic distribution, the same haplotypes of T. lobariacearum consistently associated with a given host species. Our results suggest that the Lobaria hosts create a selective environment for the lichenicolous fungus. Both the pathogen and the host populations exhibited substantial genetic structure. However, evolutionary and demographic histories differed between the parasite and its hosts, as evidenced by different divergence times and tree topologies.     

Discovery of the Inhibitory Effect of a Phosphatidylinositol Derivative on P-Glycoprotein by Virtual Screening Followed by In Vitro Cellular Studies

P-glycoprotein is capable of effluxing a broad range of cytosolic and membrane penetrating xenobiotic substrates, thus leading to multi-drug resistance and posing a threat for the therapeutic treatment of several diseases, including cancer and central nervous disorders. Herein, a virtual screening campaign followed by experimental validation in Caco-2, MDKCII, and MDKCII mdr1 transfected cell lines has been conducted for the identification of novel phospholipids with P-gp transportation inhibitory activity. Phosphatidylinositol-(1,2-dioctanoyl)-sodium salt (8∶0 PI) was found to significantly inhibit transmembrane P-gp transportation in vitro in a reproducible-, cell line-, and substrate-independent manner. Further tests are needed to determine whether this and other phosphatidylinositols could be co-administered with oral drugs to successfully increase their bioavailability. Moreover, as phosphatidylinositols and phosphoinositides are present in the human diet and are known to play an important role in signal transduction and cell motility, our finding could be of substantial interest for nutrition science as well.     

Interactions of donor sources and media influence the histo‐morphological quality of full‐thickness skin models

Human artificial skin models are increasingly employed as non‐animal test platforms for research and medical purposes. However, the overall histopathological quality of such models may vary significantly. Therefore, the effects of manufacturing protocols and donor sources on the quality of skin models built‐up from fibroblasts and keratinocytes derived from juvenile foreskins is studied. Histo‐morphological parameters such as epidermal thickness, number of epidermal cell layers, dermal thickness, dermo‐epidermal adhesion and absence of cellular nuclei in the corneal layer are obtained and scored accordingly. In total, 144 full‐thickness skin models derived from 16 different donors, built‐up in triplicates using three different culture conditions were successfully generated. In univariate analysis both media and donor age affected the quality of skin models significantly. Both parameters remained statistically significant in multivariate analyses. Performing general linear model analyses we could show that individual medium‐donor‐interactions influence the quality. These observations suggest that the optimal choice of media may differ from donor to donor and coincides with findings where significant inter‐individual variations of growth rates in keratinocytes and fibroblasts have been described. Thus, the consideration of individual medium‐donor‐interactions may improve the overall quality of human organ models thereby forming a reproducible test platform for sophisticated clinical research.     

Reasons for Journal Impact Factor Changes: Influence of Changing Source Items

Both the concept and the application of the impact factor (IF) have been subject to widespread critique, including concerns over its potential manipulation. This study provides a systematic analysis of significant journal Impact Factor changes, based on the relative contribution of either one or both variables of the IF equation (i.e. citations / articles as the numerator / denominator of the quotient). A cohort of JCR-listed journals which faced the most dramatic absolute IF changes between 2013 and 2014 (ΔIF ≥ 3.0, n = 49) was analyzed for the causes resulting in IF changes that theses journals have experienced in the last five years. Along with the variation by number of articles and citations, this analysis includes the relative change of both variables compared to each other and offers a classification of `valid`and `invalid`scenarios of IF variation in terms of the intended goal of the IF to measure journal quality. The sample cohort features a considerable incidence of IF increases (18%) which are qualified as `invalid`according to this classification because the IF increase is merely based on a favorably changing number of articles (denominator). The results of this analysis point out the potentially delusive effect of IF increases gained through effective shrinkage of publication output. Therefore, careful consideration of the details of the IF equation and possible implementation of control mechanisms versus the volatile factor of number of articles may help to improve the expressiveness of this metric.     

Cryopreservation of Endothelial Cells in Various Cryoprotective Agents and Media – Vitrification versus Slow Freezing Methods

Vitrification of endothelial cells (MHECT-5) has not previously been compared with controlled slow freezing methods under standardized conditions. To identify the best cryopreservation technique, we evaluated vitrification and standardized controlled-rate -1°C/minute cell freezing in a -80°C freezer and tested four cryoprotective agents (CPA), namely dimethyl sulfoxide (DMSO), ethylene glycol (EG), propylene glycol (PG), and glycerol (GLY), and two media, namely Dulbecco''s modified Eagle medium Ham’s F-12 (DMEM)and K⁺-modified TiProtec (K⁺TiP), which is a high-potassium-containing medium. Numbers of viable cells in proliferation were evaluated by the CellTiter 96® A_Queous One Solution Cell Proliferation Assay (Promega Corporation, Mannheim, Germany). To detect the exact frozen cell number per cryo vial, DNA content was measured by using Hoechst 33258 dye prior to analysis. Thus, results could be evaluated unconstrained by absolute cell number. Thawed cells were cultured in 25 cm² cell culture flasks to confluence and examined daily by phase contrast imaging. With regard to cell recovery immediately after thawing, DMSO was the most suitable CPA combined with K⁺TiP in vitrification (99 ±0.5%) and with DMEM in slow freezing (92 ±1.6%). The most viable cells in proliferation after three days of culture were obtained in cells vitrificated by using GLY with K⁺TiP (308 ±34%) and PG with DMEM in slow freezing (280 ±27%).     

High diversity of thermophilic cyanobacteria in Rupite hot spring identified by microscopy,cultivation, single-cell PCR and amplicon sequencing

Extremophiles - Genotypic and morphological diversity of cyanobacteria in the Rupite hot spring (Bulgaria) was investigated by means of optical microscopy, cultivation, single-cell PCR, and 16S...