The dynamics of two interacting giant

In this thesis, the large N limit of the anomalous dimension of operators in N = 4 super Yang-Mills theory described by restricted Schur Polynomials are studied. The operators studied in this thesis are labelled by Young Di- agrams which have two columns (both long) so that the classical dimension of these operators is O(N). At large N these two column operators mix with each other but are decoupled from operators with n 6= 2 columns. The planar approximation does not does not capture the large N dynamics. The dilata- tion operator is explicitly evaluated for 2, 3, and 4 impurities. In all three cases, for a certain limit, the dilatation operator is a discretized version of the second derivative de ned on a lattice emerging from the Young Diagram itself. The dilatation operator is diagonalized numerically. All eigenvalues are an integer multiple of 8g2 Y M and there are interesting degeneracies in the spectrum. The spectrum obtained in this thesis for the one loop anomalous dimension operator is reproduced by a collection of harmonic oscillators. The equivalence to harmonic oscillators generalizes giant graviton results known for the BPS sector and further implies that the Hamiltonian de ned by the one loop large N dilatation operator is integrable. This is an example of an integrable dilatation operator, obtained by summing both the planar and the non-planar diagrams

TMEM203 is a binding partner and regulator of STING-mediated inflammatory signaling in macrophages

Regulation of IFN signaling is critical in host recognition and response to pathogens while its dysregulation underlies the pathogenesis of several chronic diseases. STimulator of IFN Genes (STING) has been identified as a critical mediator of IFN inducing innate immune pathways, but little is known about direct coregulators of this protein. We report here that TMEM203, a conserved putative transmembrane protein, is an intracellular regulator of STING-mediated signaling. We show that TMEM203 interacts, functionally cooperates, and comigrates with STING following cell stimulation, which in turn leads to the activation of the kinase TBK1, and the IRF3 transcription factor. This induces target genes in macrophages, including IFN-β. Using Tmem203 knockout bone marrow-derived macrophages and transient knockdown of TMEM203 in human monocyte-derived macrophages, we show that TMEM203 protein is required for cGAMPinduced STING activation. Unlike STING, TMEM203 mRNA levels are elevated in T cells from patients with systemic lupus erythematosus, a disease characterized by the overexpression of type I interferons. Moreover, TMEM203 mRNA levels are associated with disease activity, as assessed by serum levels of the complement protein C3. Identification of TMEM203 sheds light into the control of STING-mediated innate immune responses, providing a potential novel mechanism for therapeutic interventions in STING-associated inflammatory diseases

Surprisingly Simple Spectra

The large N limit of the anomalous dimensions of operators in ${\cal N}=4$ super Yang-Mills theory described by restricted Schur polynomials, are studied. We focus on operators labeled by Young diagrams that have two columns (both long) so that the classical dimension of these operators is O(N). At large N these two column operators mix with each other but are decoupled from operators with $n\ne 2$ columns. The planar approximation does not capture the large N dynamics. For operators built with 2, 3 or 4 impurities the dilatation operator is explicitly evaluated. In all three cases, in a certain limit, the dilatation operator is a lattice version of a second derivative, with the lattice emerging from the Young diagram itself. The one loop dilatation operator is diagonalized numerically. All eigenvalues are an integer multiple of $8g_{YM}^2$ and there are interesting degeneracies in the spectrum. The spectrum we obtain for the one loop anomalous dimension operator is reproduced by a collection of harmonic oscillators. This equivalence to harmonic oscillators generalizes giant graviton results known for the BPS sector and further implies that the Hamiltonian defined by the one loop large $N$ dilatation operator is integrable. This is an example of an integrable dilatation operator, obtained by summing both planar and non-planar diagrams.Comment: 34 page

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Interferon gene regulation: not all roads lead to Tolls

Many infectious agents elicit a type I interferon response but, until recently, the molecular details that coordinate interferon (IFN)-alpha and -beta expression during infection were unknown. Innate immune pattern recognition receptors, including Toll-like receptors and cytoplasmic RNA helicases such as retinoic acid-inducible gene, that sense viral nucleic acids have been discovered. Using distinct mechanisms, these receptors trigger cellular signaling pathways, culminating in the activation of interferon regulatory factors that transcriptionally induce IFN-alpha and IFN-beta genes

The E3 ubiquitin ligase Ro52 negatively regulates IFN-beta production post-pathogen recognition by polyubiquitin-mediated degradation of IRF3

Induction of type I IFNs is a fundamental cellular response to both viral and bacterial infection. The role of the transcription factor IRF3 is well established in driving this process. However, equally as important are cellular mechanisms for turning off type I IFN production to limit this response. In this respect, IRF3 has previously been shown to be targeted for ubiquitin-mediated degradation postviral detection to turn off the IFN-beta response. In this study, we provide evidence that the E3 ligase Ro52 (TRIM21) targets IRF3 for degradation post-pathogen recognition receptor activation. We demonstrate that Ro52 interacts with IRF3 via its C-terminal SPRY domain, resulting in the polyubiquitination and proteasomal degradation of the transcription factor. Ro52-mediated IRF3 degradation significantly inhibits IFN-beta promoter activity, an effect that is reversed in the presence of the proteasomal inhibitor MG132. Specific targeting of Ro52 using short hairpin RNA rescues IRF3 degradation following polyI:C-stimulation of HEK293T cells, with a subsequent increase in IFN-beta production. Additionally, shRNA targeting of murine Ro52 enhances the production of the IRF3-dependent chemokine RANTES following Sendai virus infection of murine fibroblasts. Collectively, this demonstrates a novel role for Ro52 in turning off and thus limiting IRF3-dependent type I IFN production by targeting the transcription factor for polyubiquitination and subsequent proteasomal degradation

A strategy for reducing maternal and newborn deaths by 2015 and beyond.

BACKGROUND: Achievement of Millennium Development Goal (MDG) 4 for child survival requires acceleration of gains in newborn survival, and current trends in improving maternal health will also fall short of reaching MDG 5 without more strategic actions. We present a Maternal Newborn and Child Health (MNCH) strategy for accelerating progress on MDGs 4 and 5, sustaining the gains beyond 2015, and further bringing down maternal and child mortality by two thirds by 2030. DISCUSSION: The strategy takes into account current trends in coverage and cause-specific mortality, builds on lessons learned about what works in large-scale implementation programs, and charts a course to reach those who do not yet access services. A central hypothesis of this strategy is that enhancing interactions between frontline workers and mothers and families is critical for increasing the effective coverage of life-saving interventions. We describe a framework for measuring and evaluating progress which enables continuous course correction and improvement in program performance and impact. SUMMARY: Evidence for the hypothesis and impact of this strategy is being gathered and will be synthesized and disseminated in order to advance global learning and to maximise the potential to improve maternal and neonatal survival