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Functional Diversification of Rice AGO1 Proteins
No full textGlobal demand for food is outpacing gains from conventional plant breeding. Scientists have turned to molecular crop breeding techniques to increase crop output and mitigate global hunger; however, a common setback in this process is the pleiotropic effects of target genes. We need to develop strategies to specifically modulate desired traits without incurring undesired penalties. Natural evolution frequently balances such tradeoffs through extensive regulation, which we can leverage to produce more specific results. Reproductive development is an important target of breeding efforts due to its direct effect on yield. Rice, a major staple food crop for half the world’s population, is a model organism due to its well-annotated genome and genetic tractability, making it an ideal candidate for molecular study. Small RNAs (sRNAs) are an important and widespread mechanism of regulation in plants, and sRNA pathways have expanded over time. To study the sRNA landscape during anther development of rice, we created sRNA and expression atlases of anther development in Kitaake rice and discovered new compositionally and temporally distinct clusters of 21- and 24-nt phasiRNAs. Though there are thousands of sRNAs, there are only 19 Argonaute (AGO) proteins in rice, which load sRNAs and carry out gene repression, making them attractive candidates for breeding efforts. We studied the functional diversification of the four rice AGO1 proteins, since AtAGO1 is known to play a role in plant development and stress response, thus making AGO1 a good candidate for study regarding regulation for specificity. We studied different potential mechanisms of differentiation and found evidence of neofunctionalization based on spatiotemporal expression and subcellular localization. Furthermore, we found an erect panicle mutant phenotype of the osago1b single mutant. These findings provide us with potential molecular mechanisms driving specific functions among paralogs, which we can leverage to uncouple plieotropic effects in crop breeding efforts
Defining B cell responses to emerging viral pathogens
No full textThe primary series of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines greatly reduced the burden of the coronavirus disease 2019 (COVID-19) pandemic and saved millions of lives. However, waning levels of circulating neutralizing antibodies and the continuous emergence of SARS-CoV-2 variants with increasing numbers of mutations in the spike (S) protein have decreased vaccine effectiveness and led to a recommendation for booster immunizations. In addition, new vaccines based on circulating variants have been developed to enhance the ability of induced antibodies to combat such variants. However, a critical unanswered question was how prior exposure to the ancestral SARS-CoV-2 strain impacts the subsequent immune response following exposure to variant viruses. Specifically, do variant-based booster immunizations induce de novo B cell responses to that variant, or do they primarily recall preexisting B cells targeted against shared epitopes? Understanding this distinction is essential for the rational design of vaccine strategies that can induce broadly neutralizing antibodies against mutating viruses. Herein, we evaluated antigen-specific B cell responses following SARS-CoV-2 mRNA-based booster immunizations in humans. Using ultrasound-guided fine needle aspiration to serially sample draining axillary lymph nodes, we showed that boosting with either the ancestral SARS-CoV-2 mRNA vaccine or the bivalent B.1.351/B.1.617.2 (Beta/Delta) mRNA vaccine elicited robust S-specific germinal center (GC) B cell responses in all sampled participants. These GC responses persisted for at least eight weeks post-booster immunization, leading to significantly more mutated antigen-specific bone marrow plasma cell (BMPC) and memory B cell (MBC) compartments. We also showed that S-specific plasmablast and GC responses predominantly originated from preexisting clonal lineages, which is consistent with our observation that most MBC-derived monoclonal antibodies (mAbs) recognized the original SARS-CoV-2 S protein. Nonetheless, using a more targeted sorting approach, we isolated mAbs that recognized the BA.1 S protein but not the original SARS-CoV-2 S protein from individuals who received the mRNA-1273.529 booster, suggesting that immunization with the monovalent B.1.1.529 BA.1-matched vaccine could induce rare de novo B cell responses against novel epitopes in the B.1.1.529 BA.1 S protein. Therefore, SARS-CoV-2 booster immunizations in humans induce robust GC B cell responses, and immunization with a distinct antigen can generate de novo B cell responses targeting variant-specific epitopes. Over the course of the COVID-19 pandemic, a dozen mAbs that target the virus S protein have been approved for clinical use in treating those infected by, or exposed to, SARS-CoV-2. These antibodies, which largely target the receptor-binding domain (RBD) of the S protein, were all raised against and efficiently neutralize the original SARS-CoV-2 strain (WA1/2020). While WA1/2020-targeting antibodies can provide a degree of protection against emerging variants, including those with minor mutations, they may lose efficacy against variants with significant changes in their S proteins. In fact, all clinically authorized mAbs are now rendered inactive by the latest Omicron subvariants, raising the question of whether antibodies that are specifically tailored to the unique features of Omicron can maintain efficacy against newer, more divergent Omicron subvariants. Herein, we assessed the ability of Omicron BA.1-specific mAbs to recognize and neutralize recently emerged SARS-CoV-2 Omicron subvariants. Out of six mAbs tested, only one mAb, 1A05, demonstrated broad binding and neutralization capacity against multiple SARS-CoV-2 Omicron subvariants, from BA.1 through HV.1. Prophylactic administration of 1A05 significantly reduced infectious virus titers for Omicron BA.5 in the lungs, nasal turbinate, and nasal wash of infected animals. Structural analysis of 1A05 Fab fragment in complex with Omicron BA.1 RBD using cryo-electron microscopy (cryo-EM) showed that the bulk of the 1A05 footprint overlapped with the receptor-binding motif (RBM), allowing 1A05 to achieve neutralization by blocking ACE2 binding. However, with the continuous evolution of Omicron subvariants and the emergence of antibody-evading JN.1, 1A05 lost efficacy, indicating that Omicron BA.1-specific B cell responses may lose efficacy against newer, more divergent Omicron subvariants, which emphasizes the need for mAbs with enhanced breadth and resilience against the continuously evolving SARS-CoV-2. Overall, the studies I describe here provide crucial insights into how prior exposure to SARS-CoV-2 shapes subsequent immune responses, particularly in the context of variant-adapted vaccines. This knowledge not only informs strategies for combating the ongoing evolution of SARS-CoV-2 but also helps us prepare against future emerging viruses
Letter to Congress from Harvey A. Friedman Center for Aging, June 24, 2025
Get PDFLetter to Members of Congress: We are gerontological social work researchers with expertise in productive aging; that is, activities that produce goods or services for society, whether paid for or not. We mainly focus on risk and protective factors to employment, caregiving, and volunteering in later life, and the many health, economic, and social outcomes.
Attached are peer reviewed scientific journal articles and policy briefs that underscore the importance of social policies that enable older adults to contribute to society through productive aging. In simple terms, increasing opportunities for older adults to remain productively engaged through work, volunteering, and caregiving is good for individuals, families, the economy, and society at large.
Briefly, we outline a few research findings as they relate to Protecting Older Workers Against Age Discrimination Act (POWADA, S. 1820), Lifespan Respite Care Reauthorization Act (S. 830), The Older Americans Act, namely the Senior Community Service Employment Program, and Civic Engagement
Navigating Uncertainty: An Ethnography of an Abortion Clinic in Post-Dobbs Ohio
No full textThis dissertation explores how an independent abortion clinic in Ohio navigated legal and political uncertainty following the Supreme Court’s Dobbs v. Jackson Women’s Health decision, which overturned federal abortion protections. I argue that uncertainty became a mechanism of reproductive governance, influencing both patient and provider capacities to seek and provide abortion care. Through ethnographic fieldwork conducted six months post-Dobbs, I examine how the clinic resisted state-imposed constraints to maintain patient access amid shifting legislation, including Ohio’s six-week abortion ban (OH SB23) and additional legal challenges. The study highlights three key areas: (1) the clinic’s efficiency-driven organizational structure, which enabled rapid adaptation; (2) strategies to disrupt state-mandated fetal personhood claims, such as reinterpretations of ultrasound protocols; and (3) the politicization of medical authority during Ohio’s 2023 citizen-initiated ballot initiative to constitutionally protect abortion. By centering on-the-ground strategies, this research challenges narratives of clinics as passive victims of restrictive laws, reframing them as dynamic spaces of tactical resistance
From Anorthosite to Silicic Volcanics: Photometry, Composition, and Buoyancy of Crustal Rock Types on the Moon
No full textTo better constrain the formation and evolution of the lunar crust, this dissertation addresses two key aspects of lunar crustal formation: the primary feldspathic crust, formed during solidification of an ancient lunar magma ocean (LMO), and non-mare silicic volcanic constructs, which represent either secondary or tertiary crustal formation processes. Specifically, we performed photometry on Lunar Reconnaissance Orbiter Camera (LROC) Narrow Angle Camera (NAC) images to determine the single-scattering albedo (SSA) of surface features that expose these two non-mare crustal rock types. Using digital terrain models (DTMs) derived from LROC NAC images of each analysis region, we accounted for potential topographic effects by calculating the local incidence and emission at the scale of the DTM (2-5 meters per pixel), producing high spatial resolution SSA values that correlate approximately linearly with the mafic mineral content of mature regolith. Chapter 2 uses photometric analyses of LROC NAC images and the relationship between SSA and mafic mineral content to assess the extent and distribution of plagioclase within the Moon’s primary crust. Previous spectral analyses have detected the presence of highly pure plagioclase in numerous locations in uplift features, leading workers to infer that a thick, global layer of highly pure anorthosite (“PAN”; \u3e 98% plagioclase) exists in the Moon’s crust. The production of this layer would have required highly efficient separation of plagioclase crystals from mafic cumulates and melt during the formation of the primary crust. We determined the composition of eight uplift features across the lunar surface where spectral analyses have determined the presence of highly pure anorthosite. Of the sites analyzed, only the inner Rook Mountains of Orientale Basin possess SSA values that indicate the presence of high percentages of PAN over extensive portions of the uplifted units. Other analysis locations contain only small exposures of highly pure anorthositic material, with the majority of material indicating a feldspathic crust with anorthosite noritic (~75-80% plagioclase) compositions. Our results suggest that the primary flotation crust within the LMO contained moderate proportions of trapped melt, with high separation efficiencies occurring in some cases on local scales. Chapters 3 and 4 focus on examples of lunar nonmare volcanism, which morphologic and spectral analyses have determined formed from highly viscous, silicic magmas. These features could be instances of the Moon’s secondary crust, formed from the silica-enriched residual melt derived from silicate liquid immiscibility or extended fractional crystallization of a basaltic melt reservoir, or tertiary crust, created from partial remelting of fertile crust by basaltic underplating. Evaluating the degree and distribution of silicic material within and between non-mare silicic volcanic features can help elucidate likely formation mechanism(s). In chapter 3, we performed photometric analyses using LROC NAC images to evaluate the compositions of two regions of nonmare silicic volcanism: the Gruithuisen Domes (GD) and the Compton-Belkovich Volcanic Complex (CBVC). Analyses of the SSA values within separate morphologic units within the CBVC revealed high values of SSA, indicating the presence of a range of rhyolitic (SiO2 ~72-77 wt%) compositions mixed with pyroclastic ejecta. On the basis of this compositional variation, we suggest that the CBVC was formed from highly silicic melt produced from extended fractional crystallization. Analysis of the distribution of SSA values of the Gruithuisen Domes indicates extensive mixing between components with distinct compositions: a silica-rich dome component of dacitic or rhyolitic composition (SiO2 = 67-70 wt%) material and at least one or more FeO-rich component. The smaller range of silicic compositions in this region supports previous hypotheses that the Gruithuisen Domes formed from melt generated from crustal partial melting; however, the unknown origin of the more FeO-rich component complicates interpretations. Likely sources of the more FeO-rich materials are ejecta deposits from nearby large impact craters such as Iridum and Mairan, and mare basalt ejected onto the domes by nearby impact craters into the embaying mare basalts. In Chapter 4, we test the hypothesis of multiple sources of material on the Gruithuisen Domes and implications for the mode of their emplacement. Geologic and morphologic studies indicate the presence of three major compositional types within and surrounding the Gruithuisen Domes: (1) silicic dome material, (2) non-mare KREEP-rich material exemplified by deposits to the north of the domes, and (3) basaltic mare material such as embays the domes. Using published compositions of Apollo 12 and Apollo 14 samples to represent component compositions, we calculate the concentrations of FeO (wt%) and Th (ppm) when various proportions of the components are linearly mixed. Based on the observed FeO and calculated Th concentrations across Gamma and Delta Dome, we suggest that the regolith across the domes is composed of mostly nonmare KREEP material (50-80%) mixed with smaller amounts of dome material (15-40%) and a variable amount of mare material that is usually \u3c 10% but could be as large as 20%. These mixing proportions differ in and around impact craters where dome material can compose up to 100% of the surface regolith. We infer that the Domes formed by a mechanism that facilitated this scale of mixing. We hypothesize that buoyant, silicic melt formed by crustal partial melting in the shallow upper crust rose into the megaregolith, where it attained neutral buoyancy before breaching the surface. As silicic melt continued to rise, buoyancy forces from the melt exerted pressure on the material above it, inflating and doming the surface from below, forming the Gruithuisen Domes. After emplacement, impacts exposed and excavated the silicic dome material, where it mixed with preexisting KREEP-rich surface regolith. Finally, local impacts into the embaying mare basalt added small amounts of basaltic material onto the domes. The analyses completed in this dissertation leverage the high spatial resolutions of LROC NAC images, enabling assessment of local-scale compositional variation. Photometric analyses of LROC NAC images facilitate the determination and comparison of compositions at the outcrop scale at multiple locations across the lunar surface, allowing us to determine both the composition of individual crustal features as well as the presence of broad compositional trends. These variations are useful for assessing both local crustal rock types and evaluating the implications of rock type variability on mechanisms of emplacement. Analyzing photometric parameters of the surface, such as SSA, derived from LROC NAC images at high resolution allows us to perform detailed and comprehensive compositional analyses that can only be rivaled by in situ data collection or sample return
BCLAF1 is a Novel Regulator of Hematopoietic Stem Cells
No full textHematopoietic stem cells (HSC) maintain both a self-renewal capacity to persist throughout life and an ability to differentiate into mature cell lineages. HSC self-renewal programs are often ectopically activated in leukemia cells to sustain developmental arrest and neoplastic proliferation. Recently, the transcriptional regulator Bclaf1 (Bcl2 associated transcription factor 1) was shown to support proliferation and block differentiation of AML blasts. Bclaf1 is ubiquitously expressed in hematopoietic cells but its function in normal hematopoiesis has not been elucidated. Our data demonstrate that BCLAF1 promotes HSC development and function. To study the role of BCLAF1 in normal HSCs, we used murine models with constitutive deletion of BCLAF1 in hematopoietic cells (Vav Cre:Bclaf1f/f) or inducible global deletion (Mx-Cre:Bclaf1f/f). We find that Vav-Cre:Bclaf1f/f mice have normal fetal liver HSC numbers at embryonic day 14.5 (E14.5), but significantly reduced HSCs at embryonic day 17.5 (E17.5). This defect persists into adult bone marrow but does not exaggerate with age. However, induced deletion of BCLAF1 in adult Mx-Cre:Bclaf1f/f mice via treatment with poly(I:C) results in normal HSC numbers in the bone marrow. This data suggests that loss of BCLAF1 impairs HSC development but does not impair maintenance of homeostatic HSC populations. To examine the function of BCLAF1-deficient HSCs, we performed transplantation of 20 sorted LSK SLAM E17.5 fetal liver HSCs from Bclaf1f/f or Vav-Cre:Bclaf1f/f mice. Donors cells from Vav-Cre:Bclaf1f/f mice have significantly reduced multilineage repopulation capacity post-transplant. Transplantation of Vav-Cre:Bclaf1f/f adult bone marrow results in a similar defect in repopulation. Although loss of BCLAF1 in adult mice did not result in a reduction in HSC numbers, interestingly, 1:1 whole bone marrow transplants of Mx-Cre:Bclaf1f/f cells also resulted in a significant defect in HSC repopulation. These data demonstrate that BCLAF1 promotes normal HSC repopulation and self-renewal. We sought to characterize the mechanism by which BCLAF1 functions to promote HSC development and function. CITEseq of fetal Vav-Cre:Bclaf1f/f LSK cells reveals a reduction in long-term repopulating HSCs. Additionally, stress response genes are upregulated in BCLAF1-deficient LSK cells across all transcriptional clusters. CUT&RUN sequencing reveals that BCLAF1 associates with chromatin throughout the genome of fetal and adult hematopoietic cells, likely through indirect mechanisms, to regulate transcriptional programs. These results establish a novel function for the transcriptional regulator BCLAF1 in limiting stress responses in HSCs to preserve HSC development during embryogenesis and repopulation function after stem cell transplant
Chaperone-Usher Pathway Pili Adhesin Conformations and Inhibitors in Urinary Tract Infections
Get PDFAntibiotic resistant bacteria are becoming increasingly difficult-to-treat resulting in increased morbidity and mortality, especially for common infections such as urinary tract infections (UTIs). Globally, UTIs afflict over 400 million people a year. Numerous different gram-negative and gram-positive bacterial species cause UTIs, including uropathogenic Escherichia coli (UPEC), Klebsiella pneumoniae, and Acinetobacter baumannii. Many of these bacterial species are listed as pathogens of urgent concern by the Center for Disease Control due to the dangerous rise and prevalence of antibiotic resistance necessitating development of new therapeutic measures. Bacteria utilize adhesin factors, such as chaperone-usher pathway (CUP) pili to gain a foothold in the bladder, where if left untreated, progress to pyelonephritis and sepsis. A model CUP pilus is the UPEC type 1 pilus which is a long extracellular fiber tipped with the two-domain mannose binding adhesin FimH. FimH facilitates UPEC attachment to the bladder epithelium and is essential to UPEC bladder infection. Due to structural interactions between the two domains, the UPEC FimH adhesin exists in a conformational equilibrium between a high-affinity relaxed state and a low-affinity tense state. Naturally occurring FimH sequence variants can allosterically shift the conformational equilibrium towards higher or lower affinity, but shifting the equilibrium to either direction leads to attenuation of UPEC in mouse models of UTI. Paradoxically, K. pneumoniae encodes a nearly identical FimH protein that is essential in bladder pathogenesis yet binds with very low-affinity. Using a combination of crystallography, in vitro binding assays, and mouse infection experiments, I delineated the structure-function relationship between the K. pneumoniae FimH conformational equilibrium and UTI pathogenesis. Despite high sequence conservation, I identified naturally occurring K. pneumoniae FimH sequence variants from human catheter infections that allosterically shifted the two-domain FimH towards higher affinity. These higher affinity FimH variants increased bladder titers in uncomplicated UTI, but not CAUTI, partially explaining the epidemiology of K. pneumoniae UTI. To develop antibiotic-sparing treatments of UTI, we developed monoclonal antibodies (mAbs) to E. coli and K. pneumoniae FimH. We identified high-affinity mAbs to purified FimH lectin domain truncate protein, but discovered that the natural conformational equilibrium of two-domain FimH decreased mAb binding affinity. Many mAbs displayed binding preference for the relaxed FimH structural state due to the structural interactions between FimH and the mAbs. We found a subset of mAbs with the same binding epitope that prevented UPEC infection in mice in an Fc-independent manner. Together, we identified a new potential treatment of E. coli and K. pneumoniae UTI and outlined a road map for future development of mAbs to bacterial adhesins. While the development of anti-adhesin therapeutics, such as ligand mimetics and mAbs, have been successful, we lack the biochemical ligand binding information needed to apply ligand mimetics to other adhesins and development of mAbs is time and labor intensive. Recent advancements in deep learning and protein structural prediction have led to the design of de novo proteins, proteins that do not exist in nature, with novel functions. We utilized protein design to create miniprotein inhibitors to the A. baumannii adhesins Abp1D and Abp2D involved in catheter-associated UTI (CAUTI). I crystallized and structurally characterized a cross-reactive miniprotein to the binding pocket of Abp1D and Abp2D. The leading miniprotein therapeutic prevented A. baumannii infection in our murine CAUTI model. Protein design offers an efficient method to create therapeutics for bacterial virulence factors and allows precise targeting of less characterized bacterial adhesins. In addition, there are numerous CUP pili among gram-negative bacteria that have diverse structures resulting in differential ligand specificity. Further showing the structural diversity of adhesins, I solved the crystal structure of the Yeh-like adhesin (YhlD) receptor binding domain highlighting a unique CUP pili adhesin binding domain structure with a mobile flap that may contribute to E. coli attachment in the gastrointestinal tract (GIT). Together, this work highlights the structural biology of CUP pili adhesins and their involvement in UTI and GIT colonization. My dissertation outlines common themes in CUP pili adhesin function, conformational dynamics, and inhibition that establish a foundational paradigm for understanding bacterial attachment in disease and therapeutic intervention
Design and Delivery of Trump Accounts: Clearing Fund and Custodian Network With Automatic Enrollment
No full textEnacting legislation established the federal Trump Accounts policy and directed the U.S. Treasury Department to implement it. Drawing upon insights and evidence from Child Development Account research conducted by the Center for Social Development and others, this brief proposes a two-step strategy for the policy’s implementation: (a) a clearing fund and custodian network and (b) a three-pathway automatic-enrollment system. The brief details the proposal and discusses its implications
The Impacts of the St. Louis Guaranteed Basic Income Program on Credit Health
No full textHow does guaranteed basic income influence the credit of recipients?
In late 2023, the City of St Louis launched a pilot program providing $500 a month for 18 months to more than 500 low-income St. Louis households with children. Researchers from the Center for Social Development and the Brown School Evaluation Center conducted a mixed-methods evaluation of the program, tracking recipients’ journeys over the pilot’s duration. This brief presents findings from analyses of administrative credit records on the effects of the St. Louis Guaranteed Basic Income Program on the credit scores, payment delinquencies, and credit utilization of participants
Living with Purpose
No full textHaving purpose is good for all of us at any age. Patrick Hill, Professor of Psychological and Brain Sciences at WashU, defines purpose as the “notion that you have daily activities you find meaningful or engaging and that give you direction for your life [and] reasons to continue going.” In a major sense, purpose can be described as the why of living, instead of the how