The study of the mechanism of Arabidopsis immutans variegation

The immutans variegation mutant of Arabidopsis has green and white sectored leaves due to lack of IMMUTANS (IM), a plastid membrane terminal oxidase that transfers electrons from plastoquinone to molecular oxygen. IM bears similarity to alternative oxidase (AOX) of mitochondrial inner membranes. IM functions in a number of redox pathways, including carotenoid biosynthesis and chlororespiration, and its activity is especially important early in chloroplast biogenesis when the photosynthetic electron transport chain is not yet fully functional. To gain insight into factors that are able to compensate for a lack of IM in the green sectors of immutans, we initiated a second site suppressor screen to identify mutants of im that have a non-variegated, all-green phenotype. We report that suppression of variegation in ATG791, an activation-tagged im line, is due to over-expression of the gene for mitochondrial AOX2. AOX2 is present and functional in chloroplast thylakoids of this line, and its presence there does not perturb steady state photosynthesis, at least under standard lab conditions. The finding that AOX2 is able to substitute for IM is surprising given that the genes for these two proteins diverged prior to the endosymbiotic events that gave rise to the eukaryotic plant cell, and they have very different substrate-specificities, functional domains, and modes of regulation, presumably optimized for function in different membrane milieu in different cellular compartments. Our results raise the intriguing possibility that AOX2 is normally dual-targeted to mitochondria and chloroplasts

Dynamic remodeling and rapid manufacturing of functional materials by ring-opening metathesis polymerization

Ring-opening metathesis polymerization (ROMP) is a powerful and broadly applicable method to synthesize polymeric materials with unique architectures and useful functions. Remarkable progress has been made on the molecular design of catalysts and monomers that allows precise control over ROMP. The research presented in this dissertation investigates ROMP behavior of cyclic olefins with different ring nature in the bulk state, which is much less explored in the literature compared to solution ROMP. Structure-property relationships were constructed to advance fundamental understanding and provide guidance for further monomer design. Potential applications of these monomers in dynamic remodeling and rapid manufacturing were also demonstrated. As ROMP is driven by the release of ring strain, a monomer-polymer equilibrium would be established for monomers with low ring strain energy. Chapter 2 investigates the reversibility of equilibrium ROMP and explores the feasibility of depolymerization in the bulk state upon a mild thermal stimulus. We conducted a systematic study on ceiling temperatures (Tc) of substituted cyclopentenes to quantitatively describe the polymerizability of the low-strain monomers both in solution and in the bulk state. This study also identified the important role of anchor group effect in Tc. With the establishment of tunable Tcs, Chapter 3 focuses on the development of thermally reversible networks for remodeling applications by employing multifunctional cyclopentenes. These neat monomers undergo ROMP at room temperature to afford mechanically robust, cross-linked polymers; at slightly elevated temperatures, the resulting polymers readily depolymerize to a free-flowing liquid. This polymerization-depolymerization process, characterized by thermal analysis and rheological tests, is triggered solely by temperature changes and is reversible for several cycles. When cyclic olefins with large ring strain energy are polymerized, ROMP becomes irreversible and highly exothermic. The heat generated can be utilized as the energy source to trigger further polymerization; ultimately, a propagating reaction wave is produced to convert the available monomer to polymer. This process is termed as frontal ring-opening metathesis polymerization (FROMP) which has great potential in manufacturing large parts of thermosets and composites in a rapid and energy-efficient manner. Since only exo- and endo-dicyclopentadiene have been reported as FROMP monomers, Chapter 4 expands the scope of monomers and builds the structure-property relationship to guide functional materials design. We investigated 30 strained cyclic olefins and correlated FROMP reactivity with the thermodynamic, kinetic and physical properties of the monomer using linear regression analysis. Due to the complexity of FROMP, linear regression did not perform well for structurally disparate monomers. Thus, machine learning approaches were applied with structural parameters of the monomer as inputs and FROMP-related properties (heat released and frontal velocity) as outputs. Models by random forest algorithm with reasonable predictability were constructed, and important features that determine FROMP behavior were also identified. With the expansion of FROMP toolbox, Chapter 5 examines the copolymerization behavior in FROMP. An unexpected non-monotonic increase in frontal velocity was observed in copolymerization with di-norbornenyl cross-linkers, which is counterintuitive to the mixing rules. We believe that the degree of cross-linking is the main contributor to this unusual behavior, which is supported by a series of copolymerization experiments with mono-norbornenyl derivatives. The copolymerization study not only provides a strategy to systematically modify materials properties (such as interfacial shear strength and mechanical properties) but also strengthens further understanding of the FROMP process

Draft Genome Sequences of Propionibacterium acnes Type Strain ATCC6919 and Antibiotic-Resistant Strain HL411PA1.

Propionibacterium acnes is a major skin commensal and is associated with acne vulgaris, the most common skin disease. Here we report the draft genome sequences of two P. acnes strains, the type strain ATCC6919 and an antibiotic-resistant strain, HL411PA1

Effective Drusen Localization for Early AMD Screening using Sparse Multiple Instance Learning

Age-related Macular Degeneration (AMD) is one of the leading causes of blindness. Automatic screening of AMD has attracted much research effort in recent years because it brings benefits to both patients and ophthalmologists. Drusen is an important clinical indicator for AMD in its early stage. Accurately detecting and localizing drusen are important for AMD detection and grading. In this paper, we propose an effective approach to localize drusen in fundus images. This approach trains a drusen classifier from a weakly labeled dataset, i.e., only the existence of drusen is known but not the exact locations or boundaries, by employing Multiple Instance Learning (MIL). Specifically, considering the sparsity of drusen in fundus images, we employ sparse Multiple Instance Learning to obtain better performance compared with classical MIL. Experiments on 350 fundus images with 96 having AMD demonstrates that on the task of AMD detection, multiple instance learning, both classical and sparse versions, achieve comparable performance compared with fully supervised SVM. On the task of drusen localization, sparse MIL outperforms MIL significantly

Efficacy and safety of combination of ulinastatin and meglumine cyclic adenosine monophosphate in the treatment of acute myocardial infarction, and its effect on serum levels of hs-CRP, cTnI and CK

Purpose: To determine the efficacy and safety of a combination of ulinastatin and meglumine cyclic adenosine monophosphate (cAMP) in the treatment of acute myocardial infarction (AMI), and its effect on serum levels of hypersensitive-c-reactive protein (hs-CRP), cardiac troponin I (cTnI), creatine kinase (CK).Methods: A total of 90 AMI patients admitted to The Second Affiliated Hospital of Qiqihar Medical College, Qiqihar City, Heilongjiang Province, China from January 2019 to January 2020 were selected and randomized (in a 1:1 ration) into control group and study group. Patients in the two groups received meglumine cAMP, while those in the study group were, in addition, treated with ulinastatin. The two groups were compared with regard to clinical efficacy, cardiac function indices, serum biochemical indices, incidence of drug-related side effects, duration and number of episodes of angina pectoris, and levels of neuroendocrine hormones.Results: The study group exhibited remarkably higher treatment effectiveness and cardiac function indices compared to the control group (p < 0.05). However, lower levels of serum biochemical indices, lower total incidence of drug toxicity, smaller number and shorter duration of angina pectoris, and lower levels of panel reactive antibodies (PRA) were observed in the study when compared to control group (p< 0.001).Conclusion: Treatment of AMI patients with the combination of ulinastatin and meglumine cAMP significantly reduces the clinical symptoms of the patients, with remarkable efficacy and high safety. Furthermore, it down-regulates serum levels of hs-CRP, cTnI and CK. Thus, the combination treatment seems superior to the conventional therapy