Towards Understanding the Mechanism of Wolbachia-Induced Cytoplasmic Incompatibility

Wolbachia is a vertically transmitted intracellular bacterium that infects a large number of arthropods and filarial nematodes. Many strains of Wolbachia manipulate host reproduction through cytoplasmic incompatibility (CI). In its simplest form, CI is a phenomenon where male host infected with Wolbachia cannot produce viable offspring with uninfected females; this apparent sterility is restored when the male host mates with Wolbachia-infected females—a phenomenon called rescue. Since Wolbachia is transmitted through the female germline, CI helps Wolbachia propagate in the host population. These properties of CI have been utilized in Wolbachia-based methods to control mosquito-borne diseases such as Dengue and Zika and these methods have proven to be effective in field trials.In recent years, pairs of Wolbachia proteins expressed by two syntenic genes have been discovered as CI factors (Cifs) that is responsible for CI induction and rescue. They are able to recapitulate the CI-like defect and rescue phenomena when expressed in transgenic Drosophila, mosquito and yeast S. Cerevisiae. Different functional models have been proposed to explain how CI factors induce and rescue CI. However, the detailed molecular mechanism remains elusive. This thesis describes projects aimed at elucidating the mechanism of Wolbachia-induced CI. In the first two projects, we aim to identify the enzymatic target of CidB—a CI factor possessing deubiquitylase (DUB) activity. DUB is an enzyme that specifically cleaves ubiquitin, an important post-translational modifier protein, from its substrates. We first developed and characterized an unbiased tool based on OtUBD to purify ubiquitylated proteins from biological samples. Using OtUBD pulldowns and proteomics, we were able to screen for candidate DUB substrates of CidB in yeast. OtUBD also proves to be a versatile, efficient, and economical new tool for general ubiquitin-related research with specific advantages over other methods, such as in detecting monoubiquitylation or ubiquitin linkages to noncanonical sites. In another project, we investigated the role of the interactions between the cognate Cif pair—CinA and CinB—in CI rescue. Through collaboration, we solved the crystal structure of the CinA-CinB complex. With structurally guided mutagenesis, we demonstrated that the binding between CinA-CinB is crucial for rescue in yeast and transgenic Drosophila systems. These experiments provide evidences to differentiate between different CI models. In summary, the studies described here offer valuable insights towards understanding of the mechanism of CI as well as a novel method to study ubiquitin-related topics in general

Risk assessment of arrhythmias related to three antiseizure medications: a systematic review and single-arm meta-analysis

ObjectiveAntiseizure medications (ASMs) are first line therapy for seizure disorders. Their effects on arrhythmias, especially the risk of arrhythmias associated with lacosamide (LCM), levetiracetam (LEV), and perampanel (PER), have been intensely investigated.MethodsWe searched four databases (PubMed, EMBASE, Cochrane Library, and Web of Science) until August 6, 2023. We used a common effects model and reported data as pooled incidence with 95% CIs. Meta-analyses were conducted to elucidate the risk of arrhythmias with different drugs, and Egger’s regression was performed to detect publication bias analysis.ResultsWe included 11 clinical trials with 1,031 participants. The pooled incidence of arrhythmias in the LEV group was 0.005 (95% CI: 0.001-0.013), while it was 0.014 in the LCM group (95% CI: 0.003-0.030). Publication bias analyses indicated no significant bias in the LEV group (t = 0.02, df = 4, p-value = 0.9852) but a significant bias in the LCM group (t = 5.94, df = 3, p-value = 0.0095). We corrected for this bias in the LCM group using the trim-and-fill method, which yielded a similar pooled incidence of 0.0137 (95% CI: 0.0036-0.0280), indicating good reliability. Due to insufficient studies, we could not conduct a meta-analysis for PER, and we analyzed them in our systematic review.ConclusionThe use of LCM significantly elevated the risk of arrhythmias, while LEV had non-significant arrhythmogenic effects. As for the arrhythmogenic effects of PER, more clinical trials are needed in the future

Engineered Ovalbumin Nanoparticles for Cancer Immunotherapy

Ovalbumin (OVA) is a protein antigen that is widely used for eliciting cellular and humoral immune responses in cancer immunotherapy. As an alternative to solute OVA, engineering approach is developed herein towards protein nanoparticles (pNPs) based on reactive electrospraying. The resulting pNPs are comprised of polymerized OVA, where individual OVA molecules are chemically linked via poly(ethylene glycol) (PEG) units. Controlling the PEG/OVA ratio allows for fine‐tuning of critical physical properties, such as particle size, elasticity, and, at the molecular level, mesh size. As the PEG/OVA ratio decreased, OVA pNPs are more effectively processed by dendritic cells, resulting in higher OT‐I CD8+ cells proliferation in vitro. Moreover, pNPs with lower PEG/OVA ratios elicit enhanced lymphatic drainage in vivo and increased uptake by lymph node macrophages, dendritic cells, and B cells, while 500 nm OVA pNPs show poor draining lymph nodes delivery. In addition, pNPs with lower PEG/OVA ratios result in higher anti‐OVA antibody titers in vivo, suggesting improved humoral immune responses. Importantly, OVA pNPs result in significantly increased median survival relative to solute OVA antigen in a mouse model of B16F10‐OVA melanoma. This work demonstrates that precisely engineered OVA pNPs can improve the overall anti‐tumor response compared to solute antigen.As an alternative to solute antigens for cancer immunotherapy, protein nanoparticles (pNPs) comprised of polymerized antigen linked by poly(ethylene glycol) units are developed based on reactive electrospraying. This engineering approach allows fine tuning the physico‐chemical properties of pNPs such as particle size, elasticity, and mesh size. These properties are related to pNPs enhanced antigen‐specific immune responses and improved anti‐tumor efficacy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/163384/3/adtp202000100-sup-0001-SuppMat.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163384/2/adtp202000100.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163384/1/adtp202000100_am.pd

Early bruising detection of ‘Korla’ pears by low-cost visible-LED structured-illumination reflectance imaging and feature-based classification models

IntroductionNondestructive detection of thin-skinned fruit bruising is one of the main challenges in the automated grading of post-harvest fruit. The structured-illumination reflectance imaging (SIRI) is an emerging optical technique with the potential for detection of bruises.MethodsThis study presented the pioneering application of low-cost visible-LED SIRI for detecting early subcutaneous bruises in ‘Korla’ pears. Three types of bruising degrees (mild, moderate and severe) and ten sets of spatial frequencies (50, 100, 150, 200, 250, 300, 350, 400, 450 and 500 cycles m-1) were analyzed. By evaluation of contrast index (CI) values, 150 cycles m-1 was determined as the optimal spatial frequency. The sinusoidal pattern images were demodulated to get the DC, AC, and RT images without any stripe information. Based on AC and RT images, texture features were extracted and the LS-SVM, PLS-DA and KNN classification models combined the optimized features were developed for the detection of ‘Korla’ pears with varying degrees of bruising.Results and discussionIt was found that RT images consistently outperformed AC images regardless of type of model, and LS-SVM model exhibited the highest detection accuracy and stability. Across mild, moderate, severe and mixed bruises, the LS-SVM model with RT images achieved classification accuracies of 98.6%, 98.9%, 98.5%, and 98.8%, respectively. This study showed that visible-LED SIRI technique could effectively detect early bruising of ‘Korla’ pears, providing a valuable reference for using low-cost visible LED SIRI to detect fruit damage

Sodium Tanshinone IIA Sulfonate Prevents Radiation-Induced Toxicity in H9c2 Cardiomyocytes

The present study was designed to elucidate the key parameters associated with X-ray radiation induced oxidative stress and the effects of STS on X-ray-induced toxicity in H9c2 cardiomyocytes. Cytotoxicity of STS and radiation was assessed by MTT. Antioxidant activity was evaluated by SOD and MDA. Apoptosis was measured by the flow cytometry, Hoechst 33258, clonogenic survival assay, and western blot. It was found that the cell viability of H9c2 cells exposed to X-ray radiation was significantly decreased in a dose-dependent manner and was associated with cell cycle arrest at the G0/G1 phase as well as apoptosis. STS treatment significantly reversed the morphological changes, attenuated radiation-induced apoptosis, and improved the antioxidant activity in the H9c2 cells. STS significantly increased the Bcl-2 and Bcl-2/Bax levels and decreased the Bax and caspase-3 levels, compared with the cells treated with radiation alone. STS treatment also resulted in a significant increase in p38-MAPK activation. STS could protect the cells from X-ray-induced cell cycle arrest, oxidative stress, and apoptosis. Therefore, we suggest the STS could be useful for the treatment of radiation-induced cardiovascular injury

Binary diamondoid molecular gels

We demonstrate the formation of gels composed of saturated carbon cage, diamondoid molecules that are rendered attractive through acid-base, non-covalent interactions (hydrogen bonding either with or without proton transfer). The gels are formed by mixing dimethyl sulfoxide (DMSO) solutions of 1-adamantanecarboxylic acid (A1C) with 1-adamantylamine (A1N). Upon mixing at vanishing concentrations, these diamondoid molecules rapidly aggregate. At approximately 3% by weight, the resulting suspension forms a percolated network. These resulting gels have elastic moduli of 10^2-10^4Pa at diamondoid concentrations in the 3-7wt% range. With increasing applied stress these gels yield and shear thin. Upon cessation of the applied stress, the gels recover their quiescent properties and demonstrate reversibility. At 1:1 mole ratio of 1-adamantanecarboxylic acid (A1C) and 1-adamantylamine (A1N), the gel’s elastic modulus increases as ϕx with x~4. Transmission Electron Microscope (TEM) images indicate that the gels are formed from a network of interwoven and branched fibers. In combination, the flow properties and TEM images indicate that the fibers can be broken down under shear and reform in the absence of shear. Both Wide-angle and Small-angle X-ray Scattering (WAXS and SAXS) are used to investigate the gel’s microstructure. Particular attention is paid to determine the applicability of models for colloidal gelation to these molecular gels

Research on the Impact of Financial Flexibility on Innovation Investment from the Perspective of Institutional Ownership

Uncertainty in the business environment brings many challenges and opportunities to enterprises. This paper studies the impact of financial flexibility on innovation investment from the perspective of institutional ownership, using data of A-share high-tech enterprises from 2014 to 2018 as the empirical analysis sample. The results show that financial flexibility can promote innovation investment. Moreover, compared with state-owned enterprises, cash flexibility plays a more significant role in promoting non-stateowned enterprises, while debt flexibility only promotes innovation investment in non-state-owned enterprises. Through further research, it is found that the size of institutional investors’ shareholding has the positive moderating effect on the relationship between financial flexibility and innovation investment. In addition, non-independent institutional investors’ shareholding plays a negative role in regulating the impact of financial flexibility on innovation investment