3 October 2019

The Chatham House Africa Programme designed the Sudan Stakeholder Dialogues series to help identify the factors that have led to the current economic crisis, the immediate steps that need to be taken to avert collapse and stabilize the economy, and the longer-term structural reforms required to set Sudan on the path to recovery. The project is funded by Humanity United.

Research Event

Event participants

Alan Boswell, Senior Analyst for South Sudan, International Crisis Group
Miklos Gosztonyi, Conflict Analyst, South Sudan, Norwegian Refugee Council
Naomi Pendle, Research Fellow, Firoz Lalji Centre for Africa, London School of Economics
Golda Abbé, Founding Member, Ghidam (Via Skype)
Chair: Teohna Williams, CEO, Business Plan for Peace

Invitation Only Research Event

Event participants

Professor Nick Binedell, Founding Director and Sasol Chair of Strategic Management, Gordon Institute of Business Science (GIBS), University of Pretoria

Invitation Only Research Event

Event participants

Miklos Gosztonyi, Conflict Analyst, South Sudan, Norwegian Refugee Council
Matthew F. Pritchard, Research and Policy Specialist, McGill University
Joshua Craze, Writer and Researcher
Teohna Williams, CEO, Business Plan for Peace

In bottom-up, label-free discovery proteomics, biological samples are acquired in a data-dependent (DDA) or data-independent (DIA) manner, with peptide signals recorded in an intact (MS1) and fragmented (MS2) form. While DDA has only the MS1 space for quantification, DIA contains both MS1 and MS2 at high quantitative quality. DIA profiles of complex biological matrices such as tissues or cells can contain quantitative interferences, and the interferences at the MS1 and the MS2 signals are often independent. When comparing biological conditions, the interferences can compromise the detection of differential peptide or protein abundance and lead to false positive or false negative conclusions.

We hypothesized that the combined use of MS1 and MS2 quantitative signals could improve our ability to detect differentially abundant proteins. Therefore, we developed a statistical procedure incorporating both MS1 and MS2 quantitative information of DIA. We benchmarked the performance of the MS1-MS2-combined method to the individual use of MS1 or MS2 in DIA using four previously published controlled mixtures, as well as in two previously unpublished controlled mixtures. In the majority of the comparisons, the combined method outperformed the individual use of MS1 or MS2. This was particularly true for comparisons with low fold changes, few replicates, and situations where MS1 and MS2 were of similar quality. When applied to a previously unpublished investigation of lung cancer, the MS1-MS2-combined method increased the coverage of known activated pathways.

Since recent technological developments continue to increase the quality of MS1 signals (e.g. using the BoxCar scan mode for Orbitrap instruments), the combination of the MS1 and MS2 information has a high potential for future statistical analysis of DIA data.

The use of protein biomarkers as surrogates for clinical endpoints requires extensive multilevel validation including development of robust and sensitive assays for precise measurement of protein concentration. Multiple reaction monitoring (MRM) is a well-established mass-spectrometric method that can be used for reproducible protein-concentration measurements in biological specimens collected via microsampling. The dried blood spot (DBS) microsampling technique can be performed non-invasively without the expertise of a phlebotomist, and can enhance analyte stability which facilitate the application of this technique in retrospective studies while providing lower storage and shipping costs, because cold-chain logistics can be eliminated. Thus, precise, sensitive, and multiplexed methods for measuring protein concentrations in DBSs can be used for de novo biomarker discovery and for biomarker quantification or verification experiments. To achieve this goal, MRM assays were developed for multiplexed concentration measurement of proteins in DBSs.

The lower limit of quantification (LLOQ) was found to have a median total coefficient of variation (CV) of 18% for 245 proteins, whereas the median LLOQ was 5 fmol of peptide injected on column, and the median inter-day CV over 4 days for measuring endogenous protein concentration was 8%. The majority (88%) of the assays displayed parallelism, whereas the peptide standards remained stable throughout the assay workflow and after exposure to multiple freeze-thaw cycles. For 190 proteins, the measured protein concentrations remained stable in DBS stored at ambient laboratory temperature for up to 2 months. Finally, the developed assays were used to measure the concentration ranges for 200 proteins in twenty same sex, same race and age matched individuals.

For more than two decades naturally presented, human leukocyte antigen (HLA)-restricted peptides (immunopeptidome) have been eluted and sequenced using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Since, identified disease-associated HLA ligands have been characterized and evaluated as potential active substances. Treatments based on HLA-presented peptides have shown promising results in clinical application as personalized T cell-based immunotherapy. Peptide vaccination cocktails are produced as investigational medicinal products under GMP conditions. To support clinical trials based on HLA-presented tumor-associated antigens, in this study the sensitive LC-MS/MS HLA class I antigen identification pipeline was fully validated for our technical equipment according to the current US Food and Drug Administration (FDA) and European Medicines Agency (EMA) guidelines.

The immunopeptidomes of JY cells with or without spiked-in, isotope labeled peptides, of peripheral blood mononuclear cells of healthy volunteers as well as a chronic lymphocytic leukemia and a bladder cancer sample were reliably identified using a data-dependent acquisition method. As the LC-MS/MS pipeline is used for identification purposes, the validation parameters include accuracy, precision, specificity, limit of detection and robustness.

Dynamic tyrosine phosphorylation is fundamental to a myriad of cellular processes. However, the inherently low abundance of tyrosine phosphorylation in the proteome and the inefficient enrichment of phosphotyrosine(pTyr)-containing peptides has led to poor pTyr peptide identification and quantitation, critically hindering researchers' ability to elucidate signaling pathways regulated by tyrosine phosphorylation in systems where cellular material is limited. The most popular approaches to wide-scale characterization of the tyrosine phosphoproteome use pTyr enrichment with pan-specific, anti-pTyr antibodies from a large amount of starting material. Methods that decrease the amount of starting material and increase the characterization depth of the tyrosine phosphoproteome while maintaining quantitative accuracy and precision would enable the discovery of tyrosine phosphorylation networks in rarer cell populations. To achieve these goals, the BOOST (Broad-spectrum Optimization Of Selective Triggering) method leveraging the multiplexing capability of tandem mass tags (TMT) and the use of pervanadate (PV) boost channels (cells treated with the broad-spectrum tyrosine phosphatase inhibitor PV) selectively increased the relative abundance of pTyr-containing peptides. After PV boost channels facilitated selective fragmentation of pTyr-containing peptides, TMT reporter ions delivered accurate quantitation of each peptide for the experimental samples while the quantitation from PV boost channels was ignored. This method yielded up to 6.3-fold boost in pTyr quantification depth of statistically significant data derived from contrived ratios, compared with TMT without PV boost channels or intensity-based label-free (LF) quantitation while maintaining quantitative accuracy and precision, allowing quantitation of over 2300 unique pTyr peptides from only 1 mg of T cell receptor-stimulated Jurkat T cells. The BOOST strategy can potentially be applied in analyses of other post-translational modifications where treatments that broadly elevate the levels of those modifications across the proteome are available.

Bacteria secrete siderophores to access iron, a key nutrient poorly bioavailable and the source of strong competition between microorganisms in most biotopes. Many bacteria also use siderophores produced by other microorganisms (exosiderophores) in a piracy strategy. Pseudomonas aeruginosa, an opportunistic pathogen, produces two siderophores, pyoverdine and pyochelin, and is also able to use a panel of exosiderophores. We first investigated expression of the various iron-uptake pathways of P. aeruginosa in three different growth media using proteomic and RT-qPCR approaches and observed three different phenotypic patterns, indicating complex phenotypic plasticity in the expression of the various iron-uptake pathways. We then investigated the phenotypic plasticity of iron-uptake pathway expression in the presence of various exosiderophores (present individually or as a mixture) under planktonic growth conditions, as well as in an epithelial cell infection assay. In all growth conditions tested, catechol-type exosiderophores were clearly more efficient in inducing the expression of their corresponding transporters than the others, showing that bacteria opt for the use of catechol siderophores to access iron when they are present in the environment. In parallel, expression of the proteins of the pyochelin pathway was significantly repressed under most conditions tested, as well as that of proteins of the pyoverdine pathway, but to a lesser extent. There was no effect on the expression of the heme and ferrous uptake pathways. Overall, these data provide precise insights on how P. aeruginosa adjusts the expression of its various iron-uptake pathways (phenotypic plasticity and switching) to match varying levels of iron and competition.

Systemic infection and proliferation of intracellular pathogens require the biogenesis of a growth-stimulating compartment. The gastrointestinal pathogen Salmonella enterica commonly forms highly dynamic and extensive tubular membrane compartments built from Salmonella-modified membranes (SMMs) in diverse host cells. Although the general mechanism involved in the formation of replication-permissive compartments of S. enterica is well researched, much less is known regarding specific adaptations to different host cell types. Using an affinity-based proteome approach, we explored the composition of SMMs in murine macrophages. The systematic characterization provides a broader landscape of host players to the maturation of Salmonella-containing compartments and reveals core host elements targeted by Salmonella in macrophages as well as epithelial cells. However, we also identified subtle host specific adaptations. Some of these observations, such as the differential involvement of the COPII system, Rab GTPases 2A, 8B, 11 and ER transport proteins Sec61 and Sec22B may explain cell line-dependent variations in the pathophysiology of Salmonella infections. In summary, our system-wide approach demonstrates a hitherto underappreciated impact of the host cell type in the formation of intracellular compartments by Salmonella.

Human leukocyte antigen (HLA) B*51:01 and endoplasmic reticulum aminopeptidase 1 (ERAP1) are strongly genetically associated with Behcet's disease (BD). Previous studies have defined two subgroups of HLA-B*51 peptidome containing proline (Pro) or alanine (Ala) at position 2 (P2). Little is known about the unconventional non-Pro/Ala2 HLA-B*51-bound peptides. We aimed to study the features of this novel subpeptidome, and investigate its regulation by ERAP1. CRISPR-Cas9 was used to generate an HLA-ABC-triple knockout HeLa cell line (HeLa.ABC-KO), which was subsequently transduced to express HLA-B*51:01 (HeLa.ABC-KO.B51). ERAP1 was silenced using lentiviral shRNA. Peptides bound to HLA-B*51:01 were eluted and analyzed by mass spectrometry. The characteristics of non-Pro/Ala2, Pro2, and Ala2 peptides and their alteration by ERAP1 silencing were investigated. Effects of ERAP1 silencing on cell surface expression of HLA-B*51:01 were studied using flow cytometry. More than 20% of peptides eluted from HLA-B*51:01 lacked Pro or Ala at P2. This unconventional group of HLA-B*51:01-bound peptides was relatively enriched for 8-mers (with relatively fewer 9-mers) compared with the Pro2 and Ala2 subpeptidomes and had similar N-terminal and C-terminal residue usages to Ala2 peptides (with the exception of the less abundant leucine at position ). Knockdown of ERAP1 increased the percentage of non-Pro/Ala2 from 20% to ~40%, increased the percentage of longer (10-mer and 11-mer) peptides eluted from HLA-B*51:01 complexes, and abrogated the predominance of leucine at P1. Interestingly knockdown of ERAP1 altered the length and N-terminal residue usage of non-Ala2&Pro2 and Ala2 but not the Pro2 peptides. Finally, ERAP1 silencing regulated the expression levels of cell surface HLA-B*51 in a cell-type-dependent manner. In conclusion, we have used a novel methodology to identify an unconventional but surprisingly abundant non-Pro/Ala2 HLA-B*51:01 subpeptidome. It is increased by knockdown of ERAP1, a gene affecting the risk of developing BD. This has implications for theories of disease pathogenesis.

The study of protein subcellular distribution, their assembly into complexes and the set of proteins with which they interact with is essential to our understanding of fundamental biological processes. Complementary to traditional assays, proximity-dependent biotinylation (PDB) approaches coupled with mass spectrometry (such as BioID or APEX) have emerged as powerful techniques to study proximal protein interactions and the subcellular proteome in the context of living cells and organisms. Since their introduction in 2012, PDB approaches have been used in an increasing number of studies and the enzymes themselves have been subjected to intensive optimization. How these enzymes have been optimized and considerations for their use in proteomics experiments are important questions. Here, we review the structural diversity and mechanisms of the two main classes of PDB enzymes: the biotin protein ligases (BioID) and the peroxidases (APEX). We describe the engineering of these enzymes for PDB and review emerging applications, including the development of PDB for coincidence detection (split-PDB). Lastly, we briefly review enzyme selection and experimental design guidelines and reflect on the labeling chemistries and their implication for data interpretation.

Archaic technology wasting time for Canberrans is in the target of new federal agency.

6 November 2019 , Volume 95, Number 6

15 April 2020

Kotaro Hama
Apr 1, 2020; 61:523-536
Patient-Oriented and Epidemiological Research

Dong-Jae Jun
May 1, 2020; 61:746-757
Research Articles

Sandi M. Azab
Mar 31, 2020; 0:jlr.D120000630v1-jlr.D120000630
Methods

Lila M. Gierasch
Apr 1, 2020; 61:465-465
Editorials

In this week's UK Tech Weekly Podcast host Matt Egan is joined by online editor at Techworld.com Scott Carey to discuss all of the news coming out of Microsoft's Build 2016 developer conference, before being joined by producer Chris to talk about the company's genocidal AI chatbot Tay's public meltdown (13:00). Then, acting editor at Macworld.co.uk David Price jumps in to discuss the apparent resolution to the Apple vs FBI fight (29:00).  

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This week host Matt Egan is rejoined by Macworld.co.uk acting editor David Price to chat about Apple's latest Macbook announcements. Then online editor at ComputerworldUK Christina Mercer jumps in to give a break down of Google's fight with the EU over antitrust infringements (13:00). Finally, ex-dating app user Scott Carey, online editor at Techworld.com gives a state of the union on dating apps, from Tinder to Bumble to Happn, if they are good for society and which one is set to corner the market (27:00).  

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Host Matt Egan is joined by producer Chris to talk about the raft of announcements coming out of the Google I/O developer conference this week, including Android N, Google assistant and Allo. Techworld.com editor Charlotte Jee joins in to discuss driverless cars (17:00) following the Queen's speech this week. Finally, acting editor at Macworld.co.uk David Price talks about terrible film adaptations of video games, from Angry Birds to World of Warcraft (29:00). Don't forget to like, share and tell your friends!  

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This week host Matt Egan is joined by first time podder and editor of PC Advisor Jim Martin to chat Microsoft Windows 10 anniversary updates and the impact on Microsoft Surface devices. Producer Chris then comes on to chat about Sky's two big NOW TV announcements, and the future of television and broadband (16:00). Finally, UKTW podcast regular David Price chats about the impact technology is having on our holidays (26:30).  

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Macworld UK’s Acting Editor David Price takes the reins for this edition, and is joined by Online Editor of Computerworld UK Scott Carey to chat about billions and billions of pounds and the acquisition of ARM by SoftBank. Second up, Staff Writer at PC Advisor and Macworld UK Christopher Minasians plugs in to the haunting world of graphics cards and makes sense of it all for the rest of us. Digital Arts Staff Writer Mimi Launder then explains why Twitter has slapped a troll right in the face in order to stand up to Internet bullying.  

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This week Ashleigh Allsopp is simultaneously fascinated and worried by the UK launch of Amazon's Dash buttons, and discusses the many wonderful and not-so-wonderful things they enable you to buy on a drunken whim. Then David Price takes his turn to shine a spotlight on Apple's mysterious tax affairs (12:20) and tries to explain why the Irish government doesn't want to be given 13 billion euros. Finally a surprisingly riled-up Neil Bennett explains why women wearing headphones are not fair game for dimwitted pick-up artists (25:00), and ponders the social conventions surrounding the place of technology in each of our lives.  

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In this week's inexplicably klaxon-heavy and fish-themed APPLE SPECIAL episode, David Price praises Apple for rescuing us from the tyranny of wired headphones, and reveals a hitherto unsuspected penchant for former Everton strikers. Chris Martin (22:41) dazzles us with his knowledge of the Apple Watch Series Two, and display some unusual headphone usage, and Henry Burell (32:51) reveals that Berlin is big, and sheds some light on the tiny corner of tech that *isn't* Apple flavoured. Join us.  

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Host Matt Egan is in a sombre mood this week as the tech industry comes to terms with a Donald Trump US presidency. Staff writer at Macworld UK dives into what this could mean for Silicon Valley, Apple products and wether social media is at fault. Then producer Chris comes on to discuss the latest addition to the VR headset market with Google's Daydream. Will it be held back by a lack of applications though? (14:45) Finally, online editor at Computerworld UK talks about the biggest data breach at a UK bank, as Tesco Bank suffers a £2.5 million cyber theft and what this means for the banking industry as a whole (25:00).  

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Matt Egan is in the presenter chair this week as he chats about Black Friday and the changing face of online retail with acting editor at Macworld UK, David Price. Then online editor at Techworld.com Scott Carey talks Facebook and its recent issues with fake news and Chinese censorship (12:00). Finally, online editor at Computerworld UK Tamlin Magee brings us up to date with the Government's Autumn Statement and what it means for the technology sector (26:00).  

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Host Matt Egan clips us round the ear and tells us to listen up as we chat yet more tech and then some other stuff about tech. Consumer tech editor at PC Advisor Chris Martin lays down his definitive opinion after he went hands on with the Nintendo Switch this week, and why the company really should have had their star plumber ready in time for launch. Tamlin Magee, Online Editor at Computerworld UK then takes us through the odd goings on at Davos, and whether or not the elite can identify with what tech actually means to real working people. To round us up, Acting Macworld UK Editor David Price explains why app prices are going up in the UK for iOS users, and why it might - might - not be UKIP's fault. Sort of.  

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We return like a nerdy phoenix for episode 66, where Henry Burrell leads David Price and Dominic Preston down the tech rabbit hole to discuss the week's news. Amazon Prime Day came and went, but what does it really mean for consumers and the media? Did you buy anything? Did you need it? The team then discuss the odd ongoing story of the man who lost copyright of an image of a monkey to... the monkey that allegedly took it. PETA got involved. It's weird. It's good to be back.  

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