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Detection of multiple autoantibodies in patients with ankylosing spondylitis using nucleic acid programmable protein arrays [11. Microarrays/Combinatorics/Display Technology]

Ankylosing Spondylitis (AS) is a common, inflammatory rheumatic disease, which primarily affects the axial skeleton and is associated with sacroiliitis, uveitis and enthesitis. Unlike other autoimmune rheumatic diseases, such as rheumatoid arthritis or systemic lupus erythematosus, autoantibodies have not yet been reported to be a feature of AS. We therefore wished to determine if plasma from patients with AS contained autoantibodies and if so, characterize and quantify this response in comparison to patients with Rheumatoid Arthritis (RA) and healthy controls. Two high-density nucleic acid programmable protein arrays expressing a total of 3498 proteins were screened with plasma from 25 patients with AS, 17 with RA and 25 healthy controls. Autoantigens identified were subjected to Ingenuity Pathway Analysis in order to determine patterns of signalling cascades or tissue origin. 44% of patients with Ankylosing Spondylitis demonstrated a broad autoantibody response, as compared to 33% of patients with RA and only 8% of healthy controls. Individuals with AS demonstrated autoantibody responses to shared autoantigens, and 60% of autoantigens identified in the AS cohort were restricted to that group. The AS patients autoantibody responses were targeted towards connective, skeletal and muscular tissue, unlike those of RA patients or healthy controls. Thus, patients with AS show evidence of systemic humoral autoimmunity and multispecific autoantibody production. Nucleic Acid Programmable Protein Arrays constitute a powerful tool to study autoimmune diseases.




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Interpretation of data underlying the link between CCD and an invertebrate iridescent virus [Invited]

No abstract




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Oxidative stress-mediated regulation of proteasome complexes [Other]

Oxidative stress has been implicated in aging and many human diseases, notably neurodegenerative disorders and various cancers. The reactive oxygen species that are generated by aerobic metabolism and environmental stressors can chemically modify proteins and alter their biological functions. Cells possess protein repair pathways to rescue oxidized proteins and restore their functions. If these repair processes fail, oxidized proteins may become cytotoxic. Cell homeostasis and viability are therefore dependent on the removal of oxidatively damaged proteins. Numerous studies have demonstrated that the proteasome plays a pivotal role in the selective recognition and degradation of oxidized proteins. Despite extensive research, oxidative stress-triggered regulation of proteasome complexes remains poorly defined. Better understanding of molecular mechanisms underlying proteasome function in response to oxidative stress will provide a basis for developing new strategies aimed at improving cell viability and recovery as well as attenuating oxidation-induced cytotoxicity associated with aging and disease. Here we highlight recent advances in the understanding of proteasome structure and function during oxidative stress and describe how cells cope with oxidative stress through proteasome-dependent degradation pathways.




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WITHDRAWN: Heralds of parallel MS: Data-independent acquisition surpassing sequential identification of data dependent acquisition in proteomics [Research]

This article has been withdrawn by the authors. This article did not comply with the editorial guidelines of MCP. Specifically, single peptide based protein identifications of 9-19% were included in the analysis and discussed in the results and conclusions. We wish to withdraw this article and resubmit a clarified, corrected manuscript for review.




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Recent Advances in Analytical Approaches for Glycan and Glycopeptide Quantitation [Review]

Growing implications of glycosylation in physiological occurrences and human disease have prompted intensive focus on revealing glycomic perturbations through absolute and relative quantification. Empowered by seminal methodologies and increasing capacity for detection, identification, and characterization, the past decade has provided a significant increase in the number of suitable strategies for glycan and glycopeptide quantification. Mass spectrometry-based strategies for glycomic quantitation have grown to include metabolic incorporation of stable isotopes, deposition of mass difference and mass defect isotopic labels, and isobaric chemical labeling, providing researchers with ample tools for accurate and robust quantitation. Beyond this, workflows have been designed to harness instrument capability for label-free quantification and numerous software packages have been developed to facilitate reliable spectrum scoring. In this review, we present and highlight the most recent advances in chemical labeling and associated techniques for glycan and glycopeptide quantification.




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Recent advances in software tools for more generic and precise intact glycopeptide analysis [Review]

Intact glycopeptide identification has long been known as a key and challenging barrier to the comprehensive and accurate understanding the role of glycosylation in an organism. Intact glycopeptide analysis is a blossoming field that has received increasing attention in recent years. Mass spectrometry (MS)-based strategies and relative software tools are major drivers that have greatly facilitated the analysis of intact glycopeptides, particularly intact N-glycopeptides. This manuscript provides a systematic review of the intact glycopeptide identification process using mass spectrometry data generated in shotgun proteomic experiments, which typically focus on N-glycopeptide analysis. Particular attention is paid to the software tools that have been recently developed in the last decade for the interpretation and quality control of glycopeptide spectra acquired using different MS strategies. The review also provides information about the characteristics and applications of these software tools, discusses their advantages and disadvantages, and concludes with a discussion of outstanding tools.




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A Pragmatic Guide to Enrichment Strategies for Mass Spectrometry-based Glycoproteomics [Review]

Glycosylation is a prevalent, yet heterogeneous modification with a broad range of implications in molecular biology. This heterogeneity precludes enrichment strategies that can be universally beneficial for all glycan classes. Thus, choice of enrichment strategy has profound implications on experimental outcomes. Here we review common enrichment strategies used in modern mass spectrometry (MS)-based glycoproteomic experiments, including lectins and other affinity chromatographies, hydrophilic interaction chromatography (HILIC) and its derivatives, porous graphitic carbon (PGC), reversible and irreversible chemical coupling strategies, and chemical biology tools that often leverage bioorthogonal handles. Interest in glycoproteomics continues to surge as MS instrumentation and software improve, so this review aims to help equip researchers with necessary information to choose appropriate enrichment strategies that best complement these efforts.




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Integrated glycoproteomics identifies a role of N-glycosylation and galectin-1 on myogenesis and muscle development [Research]

Many cell surface and secreted proteins are modified by the covalent addition of glycans that play an important role in the development of multicellular organisms. These glycan modifications enable communication between cells and the extracellular matrix via interactions with specific glycan-binding lectins and the regulation of receptor-mediated signaling. Aberrant protein glycosylation has been associated with the development of several muscular diseases suggesting essential glycan- and lectin-mediated functions in myogenesis and muscle development but our molecular understanding of the precise glycans, catalytic enzymes and lectins involved remain only partially understood. Here, we quantified dynamic remodeling of the membrane-associated proteome during a time-course of myogenesis in cell culture. We observed wide-spread changes in the abundance of several important lectins and enzymes facilitating glycan biosynthesis. Glycomics-based quantification of released N-linked glycans confirmed remodeling of the glycome consistent with the regulation of glycosyltransferases and glycosidases responsible for their formation including a previously unknown di-galactose-to-sialic acid switch supporting a functional role of these glycoepitopes in myogenesis. Furthermore, dynamic quantitative glycoproteomic analysis with multiplexed stable isotope labelling and analysis of enriched glycopeptides with multiple fragmentation approaches identified glycoproteins modified by these regulated glycans including several integrins and growth factor receptors. Myogenesis was also associated with the regulation of several lectins most notably the up-regulation of galectin-1 (LGALS1). CRISPR/Cas9-mediated deletion of Lgals1 inhibited differentiation and myotube formation suggesting an early functional role of galectin-1 in the myogenic program. Importantly, similar changes in N-glycosylation and the up-regulation of galectin-1 during postnatal skeletal muscle development were observed in mice. Treatment of new-born mice with recombinant adeno-associated viruses to overexpress galectin-1 in the musculature resulted in enhanced muscle mass. Our data form a valuable resource to further understand the glycobiology of myogenesis and will aid the development of intervention strategies to promote healthy muscle development or regeneration.




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Thermal proteome profiling in zebrafish reveals effects of napabucasin on retinoic acid metabolism [Research]

Thermal proteome profiling (TPP) allows for the unbiased detection of drug – target protein engagements in vivo. Traditionally, one cell type is used for TPP studies, with the risk of missing important differentially expressed target proteins. The use of whole organisms would circumvent this problem. Zebrafish embryos are amenable to such an approach. Here, we used TPP on whole zebrafish embryo lysate to identify protein targets of napabucasin, a compound that may affect Signal transducer and activator of transcription 3 (Stat3) signaling through an ill-understood mechanism. In zebrafish embryos, napabucasin induced developmental defects consistent with inhibition of Stat3 signaling. TPP profiling showed no distinct shift in Stat3 upon napabucasin treatment, but effects were detected on the oxidoreductase, Pora, which might explain effects on Stat3 signaling. Interestingly, thermal stability of several aldehyde dehydrogenases (Aldhs) was affected. Moreover, napabucasin activated ALDH enzymatic activity in vitro. Aldhs have crucial roles in retinoic acid metabolism and functionally we validated napabucasin-mediated activation of the retinoic acid pathway in zebrafish in vivo. We conclude that TPP profiling in whole zebrafish embryo lysate is feasible and facilitates direct correlation of in vivo effects of small molecule drugs with their protein targets.




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Isolation of acetylated and unmodified protein N-terminal peptides by strong cation exchange chromatographic separation of TrypN-digested peptides [Technological Innovation and Resources]

We developed a simple and rapid method to enrich protein N-terminal peptides, in which the protease TrypN is first employed to generate protein N-terminal peptides without Lys or Arg and internal peptides with two positive charges at their N-termini, and then the N-terminal peptides with or without N-acetylation are separated from the internal peptides by strong cation exchange chromatography according to a retention model based on the charge/orientation of peptides. This approach was applied to 20 μg of human HEK293T cell lysate proteins to profile the N-terminal proteome. On average, 1,550 acetylated and 200 unmodified protein N-terminal peptides were successfully identified in a single LC/MS/MS run with less than 3% contamination with internal peptides, even when we accepted only canonical protein N-termini registered in the Swiss-Prot database. Since this method involves only two steps, protein digestion and chromatographic separation, without the need for tedious chemical reactions, it should be useful for comprehensive profiling of protein N-termini, including proteoforms with neo-N-termini.




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Peptidomics-driven strategy reveals peptides and predicted proteases associated with oral cancer prognosis [Research]

Protease activity has been associated with pathological processes that can lead to cancer development and progression. However, understanding the pathological unbalance in proteolysis is challenging since changes can occur simultaneously at protease, their inhibitor and substrate levels. Here, we present a pipeline that combines peptidomics, proteomics and peptidase predictions for studying proteolytic events in the saliva of seventy-nine patients and their association with oral squamous cell carcinoma (OSCC) prognosis. Our findings revealed differences in the saliva peptidome of patients with (pN+) or without (pN0) lymph node metastasis and delivered a panel of ten endogenous peptides correlated with poor prognostic factors plus five molecules able to classify pN0 and pN+ patients (ROC-AUC>0.85). In addition, endo- and exopeptidases putatively implicated in the processing of differential peptides were investigated using cancer tissue gene expression data from publicly repositories reinforcing their association with poorer survival rates and prognosis in oral cancer. The dynamics of the OSCC-related proteolysis was further explored via the proteomic profiling of saliva. This revealed that peptidase/endopeptidase inhibitors exhibited reduced levels in the saliva of pN+ patients, as confirmed by SRM-MS, whilst minor changes were detected in the level of saliva proteases. Taken together, our results indicated that proteolytic activity is accentuated in the saliva of OSCC patients with lymph node metastasis and, at least in part, this is modulated by reduced levels of salivary peptidase inhibitors. Therefore, this integrated pipeline provided better comprehension and discovery of molecular features with implications in the oral cancer metastasis prognosis.




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Proteomic identification of Coxiella burnetii effector proteins targeted to the host cell mitochondria during infection [Research]

Modulation of the host cell is integral to the survival and replication of microbial pathogens. Several intracellular bacterial pathogens deliver bacterial proteins, termed ‘effector proteins’ into the host cell during infection by sophisticated protein translocation systems, which manipulate cellular processes and functions. The functional contribution of individual effectors is poorly characterised, particularly in intracellular bacterial pathogens with large effector protein repertoires. Technical caveats have limited the capacity to study these proteins during a native infection, with many effector proteins having only been demonstrated to be translocated during over-expression of tagged versions. Here we developed a novel strategy to examine effector proteins in the context of infection. We coupled a broad, unbiased proteomics-based screen with organelle purification to study the host-pathogen interactions occurring between the host cell mitochondrion and the Gram-negative, Q fever pathogen Coxiella burnetii. We identify 4 novel mitochondrially-targeted C. burnetii effector proteins, renamed Mitochondrial Coxiella effector protein (Mce) B to E. Examination of the subcellular localisation of ectopically expressed proteins confirmed their mitochondrial localisation, demonstrating the robustness of our approach. Subsequent biochemical analysis and affinity enrichment proteomics of one of these effector proteins, MceC, revealed the protein localises to the inner membrane and can interact with components of the mitochondrial quality control machinery. Our study adapts high-sensitivity proteomics to study intracellular host-pathogen interactions, providing a robust strategy to examine the sub-cellular localisation of effector proteins during native infection. This approach could be applied to a range of pathogens and host cell compartments to provide a rich map of effector dynamics throughout infection.




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Thyroglobulin interactome profiling defines altered proteostasis topology associated with thyroid dyshormonogenesis [Research]

Thyroglobulin (Tg) is a secreted iodoglycoprotein serving as the precursor for T3 and T4 hormones. Many characterized Tg gene mutations produce secretion-defective variants resulting in congenital hypothyroidism (CH). Tg processing and secretion is controlled by extensive interactions with chaperone, trafficking, and degradation factors comprising the secretory proteostasis network. While dependencies on individual proteostasis network components are known, the integration of proteostasis pathways mediating Tg protein quality control and the molecular basis of mutant Tg misprocessing remain poorly understood. We employ a multiplexed quantitative affinity purification–mass spectrometry approach to define the Tg proteostasis interactome and changes between WT and several CH-variants. Mutant Tg processing is associated with common imbalances in proteostasis engagement including increased chaperoning, oxidative folding, and engagement by targeting factors for ER-associated degradation (ERAD). Furthermore, we reveal mutation-specific changes in engagement with N-glycosylation components, suggesting distinct requirements for one Tg variant on dual engagement of both oligosaccharyltransferase complex isoforms for degradation. Modulating dysregulated proteostasis components and pathways may serve as a therapeutic strategy to restore Tg secretion and thyroid hormone biosynthesis.




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Prediction and validation of mouse meiosis-essential genes based on spermatogenesis proteome dynamics [Research]

The molecular mechanism associated with mammalian meiosis has yet to be fully explored, and one of the main reasons for this lack of exploration is that some meiosis-essential genes are still unknown. The profiling of gene expression during spermatogenesis has been performed in previous studies, yet few studies have aimed to find new functional genes. Since there is a huge gap between the number of genes that are able to be quantified and the number of genes that can be characterized by phenotype screening in one assay, an efficient method to rank quantified genes according to phenotypic relevance is of great importance. We proposed to rank genes by the probability of their function in mammalian meiosis based on global protein abundance using machine learning. Here, nine types of germ cells focusing on continual substages of meiosis prophase I were isolated, and the corresponding proteomes were quantified by high-resolution mass spectrometry. By combining meiotic labels annotated from the MGI mouse knockout database and the spermatogenesis proteomics dataset, a supervised machine learning package, FuncProFinder, was developed to rank meiosis-essential candidates. Of the candidates whose functions were unannotated, four of ten genes with the top prediction scores, Zcwpw1, Tesmin, 1700102P08Rik and Kctd19, were validated as meiosis-essential genes by knockout mouse models. Therefore,  mammalian meiosis-essential genes could be efficiently predicted based on the protein abundance dataset, which provides a paradigm for other functional gene mining from a related abundance dataset.




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Proteomic analyses identify differentially expressed proteins and pathways between low-risk and high-risk subtypes of early-stage lung adenocarcinoma and their prognostic impacts [Research]

The histopathological subtype of lung adenocarcinoma (LUAD) is closely associated with prognosis. Micropapillary or solid predominant LUAD tends to relapse after surgery at an early stage, whereas lepidic pattern shows a favorable outcome. However, the molecular mechanism underlying this phenomenon remains unknown. Here, we recruited 31 lepidic predominant LUADs (LR: low-risk subtype group) and 28 micropapillary or solid predominant LUADs (HR: high-risk subtype group). Tissues of these cases were obtained and label-free quantitative proteomic and bioinformatic analyses were performed. Additionally, prognostic impact of targeted proteins was validated using The Cancer Genome Atlas databases (n=492) and tissue microarrays composed of early-stage LUADs (n=228). A total of 192 differentially expressed proteins were identified between tumor tissues of LR and HR and three clusters were identified via hierarchical clustering excluding eight proteins. Cluster 1 (65 proteins) showed a sequential decrease in expression from normal tissues to tumor tissues of LR and then to HR and was predominantly enriched in pathways such as tyrosine metabolism and ECM-receptor interaction, and increased matched mRNA expression of 18 proteins from this cluster predicted favorable prognosis. Cluster 2 (70 proteins) demonstrated a sequential increase in expression from normal tissues to tumor tissues of LR and then to HR and was mainly enriched in pathways such as extracellular organization, DNA replication and cell cycle, and high matched mRNA expression of 25 proteins indicated poor prognosis. Cluster 3 (49 proteins) showed high expression only in LR, with high matched mRNA expression of 20 proteins in this cluster indicating favorable prognosis. Furthermore, high expression of ERO1A and FEN1 at protein level predicted poor prognosis in early-stage LUAD, supporting the mRNA results. In conclusion, we discovered key differentially expressed proteins and pathways between low-risk and high-risk subtypes of early-stage LUAD. Some of these proteins could serve as potential biomarkers in prognostic evaluation.




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A proteomic approach to understand the clinical significance of acute myeloid leukemia-derived extracellular vesicles reflecting essential characteristics of leukemia [Research]

Extracellular vesicle (EV) proteins from acute myeloid leukemia (AML) cell lines were analyzed using mass spectrometry. The analyses identified 2450 proteins, including 461 differentially expressed proteins (290 upregulated and 171 downregulated). CD53 and CD47 were upregulated and were selected as candidate biomarkers. The association between survival of patients with AML and the expression levels of CD53 and CD47 at diagnosis was analyzed using mRNA expression data from The Cancer Genome Atlas database. Patients with higher expression levels showed significantly inferior survival than those with lower expression levels. Enzyme-linked immunosorbent assay results of the expression levels of CD53 and CD47 from EVs in the bone marrow of patients with AML at diagnosis and at the time of complete remission with induction chemotherapy revealed that patients with downregulated CD53 and CD47 expression appeared to relapse less frequently. Network model analysis of EV proteins revealed several upregulated kinases, including LYN, CSNK2A1, SYK, CSK, and PTK2B. The potential cytotoxicity of several clinically applicable drugs that inhibit these kinases was tested in AML cell lines. The drugs lowered the viability of AML cells. The collective data suggest that AML-derived EVs could reflect essential leukemia biology.




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The peptide vaccine of the future [Review]

The approach of peptide-based anti-cancer vaccination has proven the ability to induce cancer-specific immune responses in multiple studies for various cancer entities. However, clinical responses remain so far limited to single patients and broad clinical applicability was not achieved. Therefore, further efforts are required to improve peptide vaccination in order to integrate this low side effect therapy into the clinical routine of cancer therapy. To design clinically effective peptide vaccines in the future, different issues have to be addressed and optimized comprising antigen target selection as well as choice of optimal adjuvants and vaccination schedules. Furthermore, the combination of peptide-based vaccines with other immuno- and molecular targeted therapies as well as the development of predictive biomarkers could further improve efficacy. In this review, current approaches in the development of peptide-based vaccines and critical implications for optimal vaccine design are discussed.




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Plasma proteomic data can contain personally identifiable, sensitive information and incidental findings [Research]

The goal of clinical proteomics is to identify, quantify, and characterize proteins in body fluids or tissue to assist diagnosis, prognosis, and treatment of patients. In this way, it is similar to more mature omics technologies, such as genomics, that are increasingly applied in biomedicine. We argue that, similar to those fields, proteomics also faces ethical issues related to the kinds of information that is inherently obtained through sample measurement, although their acquisition was not the primary purpose. Specifically, we demonstrate the potential to identify individuals both by their characteristic, individual-specific protein levels and by variant peptides reporting on coding single nucleotide polymorphisms. Furthermore, it is in the nature of blood plasma proteomics profiling that it broadly reports on the health status of an individual – beyond the disease under investigation. Finally, we show that private and potentially sensitive information, such as ethnicity and pregnancy status, can increasingly be derived from proteomics data. Although this is potentially valuable not only to the individual, but also for biomedical research, it raises ethical questions similar to the incidental findings obtained through other omics technologies. We here introduce the necessity of - and argue for the desirability for - ethical and human rights-related issues to be discussed within the proteomics community. Those thoughts are more fully developed in our accompanying manuscript. Appreciation and discussion of ethical aspects of proteomic research will allow for deeper, better-informed, more diverse, and, most importantly, wiser guidelines for clinical proteomics.




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Identification of novel serological autoantibodies in Takayasu arteritis patients using HuProt arrays [Research]

To identify novel autoantibodies of Takayasu arteritis (TAK) using HuProt array-based approach. A two-phase approach was adopted. In Phase I, serum samples collected from 40 TAK patients, 15 autoimmune disease patients, and 20 healthy subjects were screened to identify TAK-specific autoantibodies using human protein (HuProt) arrays. In Phase II, the identified candidate autoantibodies were validated with TAK-focused arrays using an additional cohort comprised of 109 TAK patients, 110 autoimmune disease patients, and 96 healthy subjects. Subsequently, the TAK-specific autoantibodies validated in Phase II were further confirmed using Western blot analysis. We identified and validated eight autoantibodies as potential TAK-specific diagnostic biomarkers, including anti-SPATA7, -QDPR, -SLC25A2, -PRH2, -DIXDC1, -IL17RB, -ZFAND4, and -NOLC1 antibodies, with AUC of 0.803, 0.801, 0.780, 0.696, 0.695, 0.678, 0.635 and 0.613, respectively. SPATA7 could distinguish TAK from healthy and disease controls with 73.4% sensitivity at 85.4% specificity, while QDPR showed 71.6% sensitivity at 86.4% specificity. SLC25A22 showed the highest sensitivity of 80.7%, but at lower specificity of 67.0%. In addition, PRH2, IL17RB and NOLC1 showed good specificities of 88.3%, 85.9% and 86.9%, respectively, but at lower sensitivities (<50%). Finally, DIXDC1 and ZFAND4 showed moderate performance as compared with the other autoantibodies. Using a decision tree model, we could reach a specificity of 94.2% with AUC of 0.843, a significantly improved performance as compared to that by each individual biomarker. The performance of three autoantibodies, namely anti-SPATA7, -QDPR and -PRH2, were successfully confirmed with Western blot analysis. Using this two-phase strategy, we identified and validated eight novel autoantibodies as TAK–specific biomarker candidates, three of which could be readily adopted in a clinical setting.




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Multi-sample mass spectrometry-based approach for discovering injury markers in chronic kidney disease [Research]

Urinary proteomics studies have primarily focused on identifying markers of chronic kidney disease (CKD) progression. Here, we aimed to determine urinary markers of CKD renal parenchymal injury through proteomics analysis in animal kidney tissues and cells and in the urine of patients with CKD. Label-free quantitative proteomics analysis based on liquid chromatography-tandem mass spectrometry was performed on urine samples obtained from 6 normal controls and 9, 11, and 10 patients with CKD stages 1, 3, and 5, respectively, and on kidney tissue samples from a rat CKD model by 5/6 nephrectomy. Tandem mass tag-based quantitative proteomics analysis was performed for primary cultured glomerular endothelial cells (GECs) and proximal tubular epithelial cells (PTECs) before and after inducing 24-h hypoxia injury. Upon hierarchical clustering, out of 858 differentially expressed proteins (DEPs) in the urine of CKD patients, the levels of 416 decreased and 403 increased sequentially according to the disease stage, respectively. Among 2965 DEPs across 5/6 nephrectomized and sham-operated rat kidney tissues, 86 DEPs showed same expression patterns in the urine and kidney tissue. After cross-validation with two external animal proteome datasets, 38 DEPs were organized; only 10 DEPs, including serotransferrin, gelsolin, poly ADP-ribose polymerase 1, neuroblast differentiation-associated protein AHNAK, microtubule-associated protein 4, galectin-1, protein S, thymosin beta-4, myristoylated alanine-rich C-kinase substrate, and vimentin were finalized by screening human GECs and PTECs data. Among these ten potential candidates for universal CKD marker, validation analyses for protein S and galectin-1 were conducted. Galectin-1 was observed to have a significant inverse correlation with renal function as well as higher expression in glomerulus with chronic injury than protein S. This constitutes the first multi-sample proteomics study for identifying key renal-expressed proteins associated with CKD progression. The discovered proteins represent potential markers of chronic renal cell and tissue damage and candidate contributors to CKD pathophysiology.




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Systematic identification of P. falciparum sporozoite membrane protein interactions reveals an essential role for the p24 complex in host infection [Research]

Sporozoites are a motile form of malaria-causing Plasmodium falciparum parasites that migrate from the site of transmission in the dermis through the bloodstream to invade hepatocytes. Sporozoites interact with many cells within the host, but the molecular identity of these interactions and their role in the pathology of malaria is poorly understood. Parasite proteins that are secreted and embedded within membranes are known to be important for these interactions, but our understanding of how they interact with each other to form functional complexes is largely unknown. Here, we compile a library of recombinant proteins representing the repertoire of cell surface and secreted proteins from the P. falciparum sporozoite and use an assay designed to detect extracellular interactions to systematically identify complexes. We identify three protein complexes including an interaction between two components of the p24 complex that is involved in the trafficking of glycosylphosphatidylinositol (GPI)-anchored proteins through the secretory pathway. Plasmodium parasites lacking either gene are strongly inhibited in the establishment of liver stage infections. These findings reveal an important role for the p24 complex in malaria pathogenesis and show that the library of recombinant proteins represents a valuable resource to investigate P. falciparum sporozoite biology.




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CMMB (Carboxylate Modified Magnetic Bead) -based isopropanol gradient peptide fractionation (CIF) enables rapid and robust off-line peptide mixture fractionation in bottom-up proteomics [Research]

Deep proteome coverage in bottom-up proteomics requires peptide-level fractionation to simplify the complex peptide mixture before analysis by tandem mass spectrometry. By decreasing the number of co-eluting precursor peptide ions, fractionation effectively reduces the complexity of the sample leading to higher sample coverage and reduced bias towards high abundance precursors that are preferentially identified in data-dependent acquisition strategies. To achieve this goal, we report a bead-based off-line peptide fractionation method termed CIF or Carboxylate modified magnetic bead-based isopropanol gradient peptide fractionation. CIF is an extension of the SP3 (single-pot solid-phase-enhanced sample preparation) strategy and provides an effective but complementary approach to other commonly used fractionation methods including strong cation exchange (SCX) and reversed phase (RP)-based chromatography. We demonstrate that CIF is an effective offline separation strategy capable of increasing the depth of peptide analyte coverage both when used alone or as a second dimension of peptide fractionation in conjunction with high pH RP. These features make it ideally suited for a wide range of proteomic applications including the affinity purification of low abundance bait proteins.




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Unraveling the MAX2 Protein Network in Arabidopsis thaliana: Identification of the Protein Phosphatase PAPP5 as a Novel MAX2 Interactor [Research]

The F-box protein MORE AXILLARY GROWTH 2 (MAX2) is a central component in the signaling cascade of strigolactones (SLs) as well as of the smoke derived karrikins (KARs) and the so far unknown endogenous KAI2 ligand (KL). The two groups of molecules are involved in overlapping and unique developmental processes, and signal-specific outcomes are attributed to perception by the paralogous α/β-hydrolases DWARF14 (D14) for SL and KARRIKIN INSENSITIVE 2/ HYPOSENSITIVE TO LIGHT (KAI2/HTL) for KAR/KL. Additionally, depending on which receptor is activated, specific members of the SUPPRESSOR OF MAX2 1 (SMAX1) – LIKE (SMXL) family control KAR/KL and SL responses. As proteins that function in the same signal transduction pathway often occur in large protein complexes, we aimed at discovering new players of the MAX2, D14 and KAI2 protein network by tandem affinity purification using Arabidopsis cell cultures. When using MAX2 as a bait, various proteins were co-purified among which general components of the Skp1-Cullin-F-box complex and members of the CONSTITUTIVE PHOTOMORPHOGENIC 9 signalosome. Here, we report the identification of a novel interactor of MAX2, a type 5 serine/threonine protein phosphatase, designated PHYTOCHROME-ASSOCIATED PROTEIN PHOSPHATASE 5 (PAPP5). Quantitative affinity purification pointed at PAPP5 as being more present in KAI2 rather than D14 protein complexes. In agreement, mutant analysis suggests that PAPP5 modulates KAR/KL-dependent seed germination in suboptimal conditions and seedling development. Additionally, a phosphopeptide enrichment experiment revealed that PAPP5 might dephosphorylate MAX2 in vivo independently of the synthetic strigolactone analog, rac-GR24. Together, by analyzing the protein complexes to which MAX2, D14 and KAI2 belong, we revealed a new MAX2 interactor, PAPP5, that might act through dephosphorylation of MAX2 to control mainly KAR/KL- related phenotypes and, hence, provide another link with the light pathway.




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Separation and identification of permethylated glycan isomers by reversed phase nanoLC-NSI-MS [Research]

High performance liquid chromatography has been employed for decades to enhance detection sensitivity and quantification of complex analytes within biological mixtures. Among these analytes, glycans released from glycoproteins and glycolipids have been characterized as underivatized or fluorescently tagged derivatives by HPLC coupled to various detection methods. These approaches have proven extremely useful for profiling the structural diversity of glycoprotein and glycolipid glycosylation but require the availability of glycan standards and secondary orthogonal degradation strategies to validate structural assignments. A robust method for HPLC separation of glycans as their permethylated derivatives, coupled with in-line MSn fragmentation to assign structural features independent of standards, would significantly enhance the depth of knowledge obtainable from biological samples. Here, we report an optimized workflow for LC-MS analysis of permethylated glycans that includes sample preparation, mobile phase optimization, and MSn method development to resolve structural isomers on-the-fly. We report baseline separation and MSn fragmentation of isomeric N- and O-glycan structures, aided by supplementing mobile phases with Li+, which simplifies adduct heterogeneity and facilitates cross-ring fragmentation to obtain valuable monosaccharide linkage information. Our workflow has been adapted from standard proteomics-based workflows and, therefore, provides opportunities for laboratories with expertise in proteomics to acquire glycomic data with minimal deviation from existing buffer systems, chromatography media, and instrument configurations. Furthermore, our workflow does not require a mass spectrometer with high-resolution/accurate mass capabilities. The rapidly evolving appreciation of the biological significance of glycans for human health and disease requires the implementation of high-throughput methods to identify and quantify glycans harvested from sample sets of sufficient size to achieve appropriately powered statistical significance. The LC-MSn approach we report generates glycan isomeric separations, robust structural characterization, and is amenable to auto-sampling with associated throughput enhancements.




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High-throughput and site-specific N-glycosylation analysis of human alpha-1-acid glycoprotein offers a great potential for new biomarker discovery [Research]

Alpha-1-acid glycoprotein (AGP) is an acute phase glycoprotein in blood, which is primarily synthetized in the liver and whose biological role is not completely understood. It consists of 45% carbohydrates that are present in the form of five N-linked complex glycans. AGP N-glycosylation was shown to be changed in many different diseases and some changes appear to be disease-specific, thus it has a great diagnostic and prognostic potential. However, AGP glycosylation was mainly analyzed in small cohorts and without detailed site-specific glycan information. Here, we developed a cost-effective method for a high-throughput and site-specific N-glycosylation LC-MS analysis of AGP which can be applied on large cohorts, aid in search for novel disease biomarkers and enable better understanding of AGP’s role and function in health and disease. The method does not require isolation of AGP with antibodies and affinity chromatography, but AGP is enriched by acid precipitation from 5 μl of bloodplasma in a 96 well format. After trypsinization, AGP glycopeptides are purified using a hydrophilic interaction chromatography based solid-phase extraction and analyzed by RP-LC-ESI-MS. We used our method to show for the first time that AGP N-glycan profile is stable in healthy individuals (14 individuals in 3 time points), which is a requirement for evaluation of its diagnostic potential. Furthermore, we tested our method on a population including individuals with registered hyperglycemia in critical illness (59 cases and 49 controls), which represents a significantly increased risk of developing type 2 diabetes. Individuals at higher risk of diabetes presented increased N-glycan branching on AGP’s second glycosylation site and lower sialylation of N-glycans on AGP’s third and AGP1’s fourth glycosylation site. Although this should be confirmed on a larger prospective cohort, it indicates that site-specific AGP N-glycan profile could help distinguish individuals who are at risk of type 2 diabetes.




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Exploring Public International Law and the Rights of Individuals with Chinese Scholars - Part One

Exploring Public International Law and the Rights of Individuals with Chinese Scholars - Part One Other resource sysadmin 29 October 2018

As part of a roundtable series, Chatham House and China University of Political Science and Law (CUPL) jointly organized this four-day meeting at Chatham House for international lawyers to discuss a wide range of issues related to public international law and the rights of individuals.

The Representative of China at the 19th Session of the Human Rights Council, Palais des Nations, Geneva. 27 February 2012. Photo: UN Photo Geneva/Violaine Martin.

The specific objectives were to:

  • create a platform for Chinese international law academics working on international human rights law issues to present their thinking and exchange ideas with counterparts from outside China;
  • build stronger understanding within the wider international law community of intellectual debates taking place in China about the international human rights system and China’s role within it;
  • support networking between Chinese and non-Chinese academics working on international human rights and related areas of international law.

The roundtable forms part of a wider Chatham House project exploring China’s impact on the international human rights system and was inspired by early discussions with a burgeoning community of Chinese academics thinking, writing (mainly in Chinese) and teaching about international human rights law.

For China University of Political Science and Law, one of the largest and most prestigious law schools in China and perhaps the only university in the world with an entire faculty of international law, the initiative is part of a drive to forge partnerships beyond China in the international law field.

The roundtable had a total of 22 participants, 10 Chinese (from universities and other academic institutions in Beijing and Shanghai) and 12 non-Chinese (from Australia, Germany, the Netherlands, Switzerland, the United Kingdom and the United States).

All discussions were held in English under the Chatham House Rule.




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Exploring Public International Law and the Rights of Individuals with Chinese Scholars - Part Two

Exploring Public International Law and the Rights of Individuals with Chinese Scholars - Part Two Other resource sysadmin 30 October 2018

As part of a roundtable series, Chatham House and China University of Political Science and Law (CUPL) held a two-day roundtable meeting in Beijing on public international law and the rights of individuals.

The Representative of China at the 19th Session of the Human Rights Council, Palais des Nations, Geneva. 27 February 2012. Photo: UN Photo Geneva/Violaine Martin.

The specific objectives were to:

  • create a platform for Chinese international law academics working on international human rights law issues to present their thinking and exchange ideas with counterparts from outside China;
  • build stronger understanding within the wider international law community of intellectual debates taking place in China about the international human rights system and China’s role within it;
  • support networking between Chinese and non-Chinese academics working on international human rights and related areas of international law.

The roundtable forms part of a wider Chatham House project exploring China’s impact on the international human rights system and was inspired by early discussions with a burgeoning community of Chinese academics thinking, writing (mainly in Chinese) and teaching about international human rights law.

For CUPL, one of the largest and most prestigious law schools in China and perhaps the only university in the world with an entire faculty of international law, the initiative is part of a drive to forge partnerships beyond China in the international law field.

The meeting in Beijing was hosted by CUPL and involved 20 participants, 10 Chinese (from universities and other academic institutions in Beijing) and 10 non-Chinese (from Australia, the Netherlands, South Africa, Switzerland, the United Kingdom and the United States).

To ensure continuity while also expanding the experts network being built, the second meeting included a mix of participants from the first meeting and some new participants.

All discussions were held in English under the Chatham House Rule.




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Exploring Public International Law and the Rights of Individuals with Chinese Scholars - Part Three

Exploring Public International Law and the Rights of Individuals with Chinese Scholars - Part Three Other resource sysadmin 30 October 2018

As part of a roundtable series, Chatham House, China University of Political Science and Law (CUPL) and the Graduate Institute Geneva held a two-day roundtable meeting in Geneva on public international law and the rights of individuals.

The Representative of China at the 19th Session of the Human Rights Council, Palais des Nations, Geneva. 27 February 2012. Photo: UN Photo Geneva/Violaine Martin.

The specific objectives were to:

  • create a platform for Chinese international law academics working on international human rights law issues to present their thinking and exchange ideas with counterparts from outside China;
  • build stronger understanding within the wider international law community of intellectual debates taking place in China about the international human rights system and China’s role within it;
  • support networking between Chinese and non-Chinese academics working on international human rights and related areas of international law.

The roundtable forms part of a wider Chatham House project exploring China’s impact on the international human rights system and was inspired by early discussions with a burgeoning community of Chinese academics thinking, writing (mainly in Chinese) and teaching about international human rights law.

For CUPL, one of the largest and most prestigious law schools in China and perhaps the only university in the world with an entire faculty of international law, the initiative is part of a drive to forge partnerships beyond China in the international law field.

The meeting in Geneva was co-hosted by the Graduate Institute Geneva and involved 19 participants, 9 Chinese (from six research institutions in Beijing and Shanghai) and 11 non-Chinese (from eight research institutions in Australia, Germany, the Netherlands, Switzerland, the United Kingdom and the United States).

To ensure continuity while also expanding the expert network being built, the third meeting included a mix of participants from the first two meetings and some new participants

All discussions were held in English under the Chatham House Rule.




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Proportionality in the Conduct of Hostilities: The Incidental Harm Side of the Assessment

Proportionality in the Conduct of Hostilities: The Incidental Harm Side of the Assessment Research paper sysadmin 6 December 2018

Clarification of international humanitarian law is important in ensuring compliance with the rule of proportionality, but a culture of compliance within armed forces and groups is also crucial.

Members of civil right defence conduct a search and rescue operation on destroyed buildings after an airstrike was carried out over the city of Jisr al-Shughur in Idlib province in Syria, on 6 May 2018. Photo: Hadi Harrat/Anadolu Agency/Getty Images.

Summary

  • Military operations are taking place with increasing frequency in densely populated areas. Such operations result in loss of life and harm to civilians, as well as damage to civilian objects, (including infrastructure providing essential services). In order to protect civilians, it is imperative that armed forces and groups comply with the rules of international humanitarian law on the conduct of hostilities, including the rule of proportionality.
  • The rule of proportionality prohibits attacks which may be expected to cause incidental loss of civilian life, injury to civilians, damage to civilian objects or a combination thereof, which would be excessive in relation to the concrete and direct military advantage anticipated. This research paper analyses the key steps that belligerents must take to give effect to the rule, with a particular focus on one side of proportionality assessments – the expected incidental harm.
  • Those undertaking proportionality assessments before or during an attack must consider whether the expected harm will be caused by the attack, and whether that harm could be expected (that is, was it reasonably foreseeable).
  • For the purpose of proportionality assessments, injury to civilians includes disease, and there is no reason in principle to exclude mental harm, even though it is currently challenging to identify and quantify it. Damage to civilian objects includes damage to elements of the natural environment.
  • Once the incidental harm to be considered has been identified, a value or weight must be assigned to it. This is then balanced against the value or weight of the military advantage anticipated from the attack to determine whether the harm would be excessive.
  • In the determination of whether the expected incidental harm would be excessive compared to the anticipated military advantage, ‘excessive’ is a wide but not indeterminate standard.
  • Belligerents should develop methodologies so that those planning and deciding attacks are provided with all necessary information on expected incidental harm, and to assist them in assigning weight to the incidental harm to be considered.
  • If it becomes apparent that the rule of proportionality will be contravened, the attack in question must be cancelled or suspended.
  • Clarification of the law is important in ensuring compliance with the rule of proportionality, but a culture of compliance within armed forces and groups, inculcated by their leaders, is also crucial.




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The Costs of Fuelling Humanitarian Aid

The Costs of Fuelling Humanitarian Aid Research paper sysadmin 7 December 2018

As humanitarian crises become more protracted and aid budgets face unprecedented scrutiny, agencies could save millions by switching from diesel and oil fuels to cleaner energy sources.

A convoy of trucks carrying humanitarian assistance provided by the World Food Program (WFP) to Southern Sudanese refugees. Photo by ASHRAF SHAZLY/AFP/Getty Images.

Download the accompanying toolkit

Most refugee and internal displacement camps are in remote locations, so humanitarian agencies consume large amounts of fuel on the transport of staff, equipment, and goods such as food and water.

Operations tend to rely on on-site electricity generation to power reception centres, clinics, schools, food storage, water-pumping and street lighting. Despite the essential role of energy in humanitarian action, and the UN’s stated commitment to carbon neutrality by 2020, there is no concerted effort to move away from fossil fuel to date.

Summary points

  • Agencies are paying too much for the energy they consume. They are overwhelmingly dependent on oil fuel for electricity generation, even though renewable energy solutions are reducing costs for those deploying them in similar conditions. Well-below-optimum standards of efficiency in buildings, generator use and fleet management are also the norm.
  • Agencies typically have few incentives to do things better. There is rarely motivation to conserve fuel, nor performance indicators for energy or fuel use. In addition, energy spending and use lacks transparency.
  • Few agencies collect and report on energy use. Where numbers are available, they are usually partial and unverified. Energy costs are rarely transparent in budgets; and donors do not know how much is being spent.
  • We estimate that around 5 per cent of humanitarian agencies’ expenditure goes on diesel, petrol and associated costs such as fixing generators. That would mean that the sector spent some $1.2 billion on polluting fuel in 2017.
  • Based on current best-practice, the sector could save at least 10 per cent of fuel costs on ground transport, 37 per cent through behaviour change and more efficient technologies, and 60 per cent on generation – all using currently available, affordable and proven practice and technology changes.
  • At current prices, this could mean operational savings of over $517 million a year for the humanitarian sector, roughly equal to 5 per cent of UNHCR’s funding gap for 2017.
  • In Kenya, annual spending on diesel and petrol for the seven agencies surveyed was $6.7 million in 2017. Replacing gensets with solar systems could create significant savings due the costs of diesel, the likelihood of protracted camp situations, and the opportunities that off-grid solar would offer for extending electricity access to refugees and local populations in Garissa and Turkana counties.
  • In Jordan, solar energy now powers the majority of camp facilities and many households. However, the use of grid electricity by humanitarian agencies’ large head offices in Amman remains high and expensive. Improving the energy efficiency of buildings is a priority for savings.
  • In Burkina Faso’s Goudoubo camp, NGO offices are desperately short of power – they have no computers or air-conditioning. Investment in renewable forms of energy for this and other camp services such as street lighting and water pumping would enable better service provision, and could drive increased rural energy access among host populations across this area of the Sahel.

Toolkit

An accompanying toolkit, Powering Ahead: Improving How We Use and Account for Energy in Humanitarian Operations, provides practical guidance for humanitarian agencies that want to make energy cost savings and reduce their carbon and emissions footprint.




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Subsidies and Sustainable Agriculture: Mapping the Policy Landscape

Subsidies and Sustainable Agriculture: Mapping the Policy Landscape Research paper sysadmin 10 December 2019

Agricultural subsidies shape production and consumption patterns, with potentially significant effects on poverty, nutrition and other sustainability concerns. This paper maps the different types of support provided by governments to the agricultural sector, and highlights some of the complex political economy dynamics that underpin the relevant policies.

Aerial view of a wheat field on 24 May 2019 in Linyi, Shandong Province of China. Photo: Getty Images.

Summary

  • Agricultural subsidies, a mainstay of government policy, have a large part in shaping production and consumption patterns, with potentially significant effects as regards poverty, food security, nutrition, and other sustainability concerns such as climate change, land use practices and biodiversity.
  • There are multiple types of direct and indirect support provided by governments to various actors in the agricultural sector; and in terms of political economy, there are complex dynamics underpinning the policies that sustain these subsidies.
  • Overall, subsidies targeting producers have the most significant effect on production, and the greater trade-distorting effect. These subsidies promote domestic production and discourage imports, leading to overproduction that is largely disposed of on the international market, with the help of export subsidies. This can tend to intensify negative environmental agricultural practices, such as cultivating marginal land, unsustainable types of intensification, or incentivizing excessive pesticide and fertilizer use.
  • On the other hand, producer subsidies that are not tied to output of a specific commodity (i.e. delinked) have far fewer distorting impacts and could help to deliver sustainable outcomes. For example, this type of subsidies can require crop diversification or be linked to conservation of permanent grassland.
  • Subsidies that enable transfers to consumers, for example through food stamp programmes, also serve to delink production from consumption, can foster healthier diets, can play an important role in delivering food accessibility and security among low-income groups, and can represent one of the less trade-distorting subsidies.
  • If subsidies are to be reformed to help promote healthier diets and encourage more sustainable production, it is essential to understand not only the type and amount of support that key countries provide, but also the domestic dynamics that can shape such policies.
  • While price support, input subsidies or investment aids remain the central pillars of programmes in large developing countries such as Brazil, China or India, other economies – notably including the EU and Japan – focus on direct payments, support for general services and set-aside schemes, as well as significant border protection. The US, for its part, has tended to focus on subsidized insurance schemes and food programmes for poorer consumers.
  • If subsidies are to deliver policy objectives, their design and implementation should delink production from consumption. For example, consumer subsidies designed to deliver nutrition and food security, or payments for environmental services to enable more environmentally friendly production systems, could prove to be the most effective, least trade-distorting means of achieving more sustainable and equitable agricultural production.
  • The political economy of food means that the removal of subsidies is often highly sensitive, and tends to be met with significant resistance. However, reform that delinks support from production through a gradual transition process could ultimately prove successful in delivering effective subsidy schemes.
  • Effective subsidy schemes must by design be truly result- and performance-based, supported by robust and objective indicators. At the same time, engaging multiple actors along key commodity value chains – including leading importing and exporting countries, traders and transporters – could lead to the development of international, commodity-specific arrangements that are able to deliver effective nutrition and sustainability goals.




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Mycobacteria excise DNA damage in 12- or 13-nucleotide-long oligomers by prokaryotic-type dual incisions and performs transcription-coupled repair [Genomics and Proteomics]

In nucleotide excision repair, bulky DNA lesions such as UV-induced cyclobutane pyrimidine dimers are removed from the genome by concerted dual incisions bracketing the lesion, followed by gap filling and ligation. So far, two dual-incision patterns have been discovered: the prokaryotic type, which removes the damage in 11–13-nucleotide-long oligomers, and the eukaryotic type, which removes the damage in 24–32-nucleotide-long oligomers. However, a recent study reported that the UvrC protein of Mycobacterium tuberculosis removes damage in a manner analogous to yeast and humans in a 25-mer oligonucleotide arising from incisions at 15 nt from the 3´ end and 9 nt from the 5´ end flanking the damage. To test this model, we used the in vivo excision assay and the excision repair sequencing genome-wide repair mapping method developed in our laboratory to determine the repair pattern and genome-wide repair map of Mycobacterium smegmatis. We find that M. smegmatis, which possesses homologs of the Escherichia coli uvrA, uvrB, and uvrC genes, removes cyclobutane pyrimidine dimers from the genome in a manner identical to the prokaryotic pattern by incising 7 nt 5´ and 3 or 4 nt 3´ to the photoproduct, and performs transcription-coupled repair in a manner similar to E. coli.




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Nonspecific DNA binding by P1 ParA determines the distribution of plasmid partition and repressor activities [Microbiology]

The faithful segregation, or “partition,” of many low-copy number bacterial plasmids is driven by plasmid-encoded ATPases that are represented by the P1 plasmid ParA protein. ParA binds to the bacterial nucleoid via an ATP-dependent nonspecific DNA (nsDNA)-binding activity, which is essential for partition. ParA also has a site-specific DNA-binding activity to the par operator (parOP), which requires either ATP or ADP, and which is essential for it to act as a transcriptional repressor but is dispensable for partition. Here we examine how DNA binding by ParA contributes to the relative distribution of its plasmid partition and repressor activities, using a ParA with an alanine substitution at Arg351, a residue previously predicted to participate in site-specific DNA binding. In vivo, the parAR351A allele is compromised for partition, but its repressor activity is dramatically improved so that it behaves as a “super-repressor.” In vitro, ParAR351A binds and hydrolyzes ATP, and undergoes a specific conformational change required for nsDNA binding, but its nsDNA-binding activity is significantly damaged. This defect in turn significantly reduces the assembly and stability of partition complexes formed by the interaction of ParA with ParB, the centromere-binding protein, and DNA. In contrast, the R351A change shows only a mild defect in site-specific DNA binding. We conclude that the partition defect is due to altered nsDNA binding kinetics and affinity for the bacterial chromosome. Furthermore, the super-repressor phenotype is explained by an increased pool of non-nucleoid bound ParA that is competent to bind parOP and repress transcription.




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Optimized incorporation of an unnatural fluorescent amino acid affords measurement of conformational dynamics governing high-fidelity DNA replication [DNA and Chromosomes]

DNA polymerase from bacteriophage T7 undergoes large, substrate-induced conformational changes that are thought to account for high replication fidelity, but prior studies were adversely affected by mutations required to construct a Cys-lite variant needed for site-specific fluorescence labeling. Here we have optimized the direct incorporation of a fluorescent un-natural amino acid, (7-hydroxy-4-coumarin-yl)-ethylglycine, using orthogonal amber suppression machinery in Escherichia coli. MS methods verify that the unnatural amino acid is only incorporated at one position with minimal background. We show that the single fluorophore provides a signal to detect nucleotide-induced conformational changes through equilibrium and stopped-flow kinetic measurements of correct nucleotide binding and incorporation. Pre-steady-state chemical quench methods show that the kinetics and fidelity of DNA replication catalyzed by the labeled enzyme are largely unaffected by the unnatural amino acid. These advances enable rigorous analysis to establish the kinetic and mechanistic basis for high-fidelity DNA replication.




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Genetic evidence for the involvement of mismatch repair proteins, PMS2 and MLH3, in a late step of homologous recombination [Cell Biology]

Homologous recombination (HR) repairs DNA double-strand breaks using intact homologous sequences as template DNA. Broken DNA and intact homologous sequences form joint molecules (JMs), including Holliday junctions (HJs), as HR intermediates. HJs are resolved to form crossover and noncrossover products. A mismatch repair factor, MLH3 endonuclease, produces the majority of crossovers during meiotic HR, but it remains elusive whether mismatch repair factors promote HR in nonmeiotic cells. We disrupted genes encoding the MLH3 and PMS2 endonucleases in the human B cell line, TK6, generating null MLH3−/− and PMS2−/− mutant cells. We also inserted point mutations into the endonuclease motif of MLH3 and PMS2 genes, generating endonuclease death MLH3DN/DN and PMS2EK/EK cells. MLH3−/− and MLH3DN/DN cells showed a very similar phenotype, a 2.5-fold decrease in the frequency of heteroallelic HR-dependent repair of restriction enzyme–induced double-strand breaks. PMS2−/− and PMS2EK/EK cells showed a phenotype very similar to that of the MLH3 mutants. These data indicate that MLH3 and PMS2 promote HR as an endonuclease. The MLH3DN/DN and PMS2EK/EK mutations had an additive effect on the heteroallelic HR. MLH3DN/DN/PMS2EK/EK cells showed normal kinetics of γ-irradiation–induced Rad51 foci but a significant delay in the resolution of Rad51 foci and a 3-fold decrease in the number of cisplatin-induced sister chromatid exchanges. The ectopic expression of the Gen1 HJ re-solvase partially reversed the defective heteroallelic HR of MLH3DN/DN/PMS2EK/EK cells. Taken together, we propose that MLH3 and PMS2 promote HR as endonucleases, most likely by processing JMs in mammalian somatic cells.




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Kapler preaches focus at camp amid rumors

Phillies manager Gabe Kapler has a little advice for the players who could be impacted most if the team signs Bryce Harper or Manny Machado.




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Hoskins would love to play alongside Harper

Will Rhys Hoskins be bummed if Bryce Harper signs elsewhere?




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Here's your guide to Angels Spring Training

It's almost time for Spring Training yet again, as Angels pitchers and catchers report to their Spring Training complex in Tempe, Ariz. on Feb. 12.




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Ausmus eager to guide Halos as camp opens

Spring Training is officially here for the Angels, with pitchers and catchers reporting to Tempe Diablo Stadium on Tuesday. And there's a new face at manager, with Brad Ausmus replacing longtime skipper Mike Scioscia this offseason.




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Covid-19: NHS staff will be offered vaccine this autumn, but JCVI recommends more limited rollout




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Covid inquiry: UKHSA chief is challenged on view that evidence for FFP3 masks is “weak”




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Tuberculosis: Disruption to health services from pandemic has allowed cases to reach record levels worldwide




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Lack of evidence for interventions offered in UK fertility centres




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Overdiagnosis of thyroid cancer




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Can Liberation Movements Really Rid Southern Africa of Corruption?

Can Liberation Movements Really Rid Southern Africa of Corruption? Expert comment sysadmin 16 December 2019

Southern Africa’s national liberation movements have survived ‘end of decade’ elections across the region. Combating corruption has been at the heart of many of the campaigns, but the question is can they succeed?

Supporters of the Namibian incumbent president and ruling party South West Africa People’s Organisation (SWAPO) presidential candidate Hage Geingob cheer and dance. Photo by GIANLUIGI GUERCIA/AFP via Getty Images.

Swapo’s victory in Namibia two weeks ago was the last in a series of recent ‘end of decade’ elections that have returned dominant parties to power across Southern Africa. However, the “enduring appeal of liberation” is wearing thin.

Experiences across the region show that if governments are to deliver on their electoral promises, they must empower institutions, actively promote a culture of accountability and transparency within their party ranks and pursue economic reforms that untangle the web of party-state-business alliances. Such actions are critical for the survival of national liberation movements as the dominant force in the politics of Southern Africa – but will be difficult to implement.

Avoid political factionalism

South Africa, Botswana, Angola and Zimbabwe all saw new presidents take over just before elections. All used the rhetoric of anti-corruption to distance themselves from the tainted image of their predecessors. But acting on this requires a shift in mind-set in parties that have always preferred to deal with their problems behind closed doors. High profile adversaries from past regimes make tempting targets but could also drive party divisions.

In Angola, the transition of power was safeguarded by an agreement that former president José Eduardo dos Santos would be immune from prosecution. But this week his son faced corruption charges before the country’s supreme court, a high-profile example of a wave of anti-corruption cases across Southern Africa, driven by dominant parties wary of their future.

The allegations against José Filemino De Sousa Dos Santos, nickname ‘Zenu’, include a $500-million fraud involving the country’s central bank. Pressure is also mounting on Zenu’s sister Isabel — once prominent in Angola, she is now absent from public life.

Other leaders have had to tread more carefully. Immunity was a luxury Cyril Ramaphosa was neither willing nor politically able to grant Jacob Zuma in South Africa. Reliant on a few close allies at the top of the party, Ramaphosa lacks foot soldiers at the grassroots level, and his campaign against corruption within the ANC has faced persistent opposition.

Rebuilding institutions and empowering authorities takes time, and with few high-profile cases to point to, people are getting restless. This is also the case in Zimbabwe, where a worsening economic situation has left policy reformers politically isolated.

Party, state, and business

Long term incumbency has blurred the distinction between the party and the state. Liberation movements have created vast party-linked business empires. Political allegiance grants access to economic resources through appointments to lucrative positions in state-owned enterprises, preferential bids for tenders and licenses, and direct access to decision makers.

In Angola, this was fuelled by oil revenues. In South Africa, state capture flourished in an environment where the ANC and its constituent elements had significant power on the panels that chose leaders for state-owned enterprises (SOEs). In Namibia, an Icelandic fishing company paid backhanders to officials for fishing rights in what has become known as the ‘Fishrot’ scandal. Zanu-PF officials’ access to preferential foreign exchange rates present them with lucrative opportunities in Zimbabwe.

Ending this bureaucratic rent seeking goes beyond appointing ‘clean’ officials, which has been central to the anti-corruption campaigns in Angola and South Africa. Governments must also allow scrutiny of the state and empower those institutions designed for that role, such as the National Prosecuting Authority and the Public Protector in South Africa. Zimbabwe’s auditor general has published an in-depth report of the state of corruption in the country’s SOEs.

Companies must also be held to account for their role in aiding, and at worst directly benefitting, from state graft. International businesses have actively sought to benefit from corruption. They are now starting to face the consequences. A former Credit Suisse banker has pleaded guilty in the US over handling alleged kickbacks in Mozambique’s $2-billion “tuna bond” scandal. Global banks and consultancies continue to feel the squeeze for their complicity in state capture in South Africa.

Competition and pluralism

National liberation movements may only have a limited window within which to act. Across the region civil society campaigns and investigative journalists have shed light on some of the worst abuses of power. Anti-corruption campaigns are starting to bite. The state will continue to play a central role in Southern African economies, an important arbiter of economic transformation able to balance the region’s highly unequal and resource-dependent economies.

But opposition, civil society and the media are also critical for the progression towards democratic competition and pluralism in Southern Africa. Parliaments remain vital for holding rulers to account. Long used to unchallenged dominance, liberation movements have significant adjustments to make to rise to the challenge of a new era.

This article was originally published in the Mail and Guardian.




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COVID-19 in South Africa: Leadership, Resilience and Inequality

COVID-19 in South Africa: Leadership, Resilience and Inequality Expert comment sysadmin 7 May 2020

In a world looking for leadership, South Africa’s president Cyril Ramaphosa has been remarkable. One year after he carried the time-worn ANC through a national election, South Africans are crying out for more.

Cyril Ramaphosa at NASREC Expo Centre in Johannesburg where facilities are in place to treat coronavirus patients. Photo by JEROME DELAY/POOL/AFP via Getty Images.

In the COVID-19 crisis so far, Cyril Ramaphosa has been widely praised for displaying the decisive leadership so many hoped for when they cast their ballot for him in May 2019. Buttressed by others such as health minister Dr Zweli Mkhize, and on a simple objective to prevent transmission, South Africa has been a lesson to the world. Act fast. Act hard.

Former president Thabo Mbeki’s disastrous response to the HIV crisis cast a long shadow over his legacy, and Ramaphosa has taken note. South Africa has had one of the tightest lockdowns in the world. No exercise. No cigarettes. No alcohol.

The lockdown was imposed when the country had only around 1,000 recorded cases and just two deaths. As a result, transmission from returning travellers has not yet led to an exponential infection rate within the community. The government’s swift reaction has bought much needed time with the peak now seemingly delayed to September or October.

Continental and national leadership

Ramaphosa has also emerged as a key focal point for Africa-wide responses. As current chair of the African Union (AU) he leads the continental engagement with the World Health Organization (WHO), and the various international finance institutions, while South African officials are working with the AU and the United Nations Economic Commission for Africa (UNECA) on a push for African debt restructuring.

He has also been active in trouble shooting to unlock external assistance to the continent, including from China and Russia. Appointing special envoys is typical of his boardroom-honed leadership style.

International and regional partnerships are vital for resilience and the arrival of 217 Cuban doctors to South Africa is strongly reminiscent of the liberationist solidarity of the Cold War era. And regional economies remain dependent on South Africa to protect their own vulnerable citizens. Following the 2008 financial crisis, it was South Africa’s regional trading relationships that remained robust, while trade with its main global partners in China and the US dropped.

Despite the plaudits, Ramaphosa remains vulnerable to challenge at home, notably around his failure to stimulate South Africa’s moribund economy. On the eve of lockdown, Moody’s joined its peers Standard and Poor’s and Fitch in giving South Africa a below investment grade credit rating. The move was a long time coming. Long mooted economic reforms were slow to materialise, and South Africa had fallen into recession.

Ramaphosa depends on a small core of close advisors and allies, initially united in apparent opposition to the kleptocratic rule of President Jacob Zuma and the deep patronage networks he created within both the party and the state. But this allegiance is being tested by economic reality. Support within the party was already drifting prior to the crisis.

Disagreements are not just technocratic – there are big ideological questions in play around the role of the state in the economy, the level of intervention, and its affordability, with key government figures sceptical of rapid market reforms. Energy minister and former union stalwart Gwede Mantashe is wary of job losses, and minister of public enterprises Pravin Gordhan protective of state-owned enterprises (SOEs). Before coronavirus hit, Ramaphosa seemed content to allow these policy disputes to play themselves out with little decisive intervention.

Slow progress on reform, against worsening economic performance, left Ramaphosa and his allies exposed. In January the president missed the UK’s African Investment Summit in order to assert control over a party meeting at which it was expected his detractors would seek to remove Gordhan.

COVID-19 has sharpened thinking

As the independently assertive - and eminently quotable - pro-market reformist finance minister Tito Mboweni stated, ‘you can’t eat ideology’. Accelerated reform and restructuring is required if the government turns to the International Monetary Fund (IMF) for assistance.

For the first time, Gordhan has been forced to deny a bailout to beleaguered state airline South African Airways (SAA), and the government’s lockdown bailout of R500 billion has been applauded by business. Much like the fiscal stimulus and recovery plan of 2018, it relies on smart spending, targeting sectors with high multiplier effects. It also includes significant reserve bank loans.

But it has been criticised for not doing enough to help the most vulnerable. There is considerable fear of what could happen when the virus takes hold in South Africa’s townships and informal settlements where social distancing is almost impossible, basic toilet facilities are shared, and HIV and TB rates high.

There are mounting concerns of the humanitarian cost of a prolonged lockdown, and the government has been faster than others in implementing a tiered lockdown system, trying to get people back to work and keep the economy afloat.

South Africa has been criticized by the UN for the use of lethal force by security forces in enforcing lockdown and, in a society plagued by corruption, there are fears legislation to stop the spread of false information could be used to restrict legitimate reporting on the virus response or other issues.

COVID-19 shines a spotlight on societies’ fault-lines worldwide. South Africa is often touted as having one of the highest levels of inequality in the world but, in a globalized economy, these divisions are international as much as they are local.

Resilience comes from within, but also depends on regional and global trading and financial systems. South Africans and international partners have long recognised Ramaphosa’s leadership qualities as an impressive voice for the global south.

But he must also be an advocate for South Africa’s poor. This crisis could accelerate implementation of his landmark pro-poor National Health Insurance and Universal Health Care programmes. Or the hit of COVID-19 on top of South Africa’s existing economic woes could see them derailed entirely. Ramaphosa must push through economic reforms at the same time as managing COVID-19 and rebuilding trust in his government.




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Webinar: South Africa's Economic Recovery Beyond COVID-19

Webinar: South Africa's Economic Recovery Beyond COVID-19 27 May 2020 — 1:00PM TO 2:00PM Anonymous (not verified) 18 May 2020

South Africa’s rapid action to prevent accelerated domestic transmission of the coronavirus has been widely praised. But, as in many countries, despite a substantial bailout, the pandemic is causing significant damage to the economy, from which it will take a long time to recover.
 
Even before the pandemic, South Africa’s economy was in recession. Citizens’ support is being tested by the need for immediate livelihood protection, and long term recovery will require public trust.
 
As the long-standing party of government, the African National Congress (ANC) is at the forefront of policy formation and debates on the future role of the state in the governance of state-owned enterprises, and transformation policies such as empowerment legislation and land reform.
 
At this webinar, Paul Mashatile, Treasurer General of the African National Congress (ANC), discusses the party’s priorities for economic recovery during and after the pandemic. He is joined for the Q&A by Enoch Godongwana, Chair of the ANC’s Economic Transformation Committee.

Read meeting summary




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Patients taking dabigatran to prevent stroke should avoid simvastatin and lovastatin, study suggests




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Long term aircraft noise is linked to incidence of high blood pressure




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Development and validation of outcome prediction models for aneurysmal subarachnoid haemorrhage: the SAHIT multinational cohort study