Bdellovibrio bacteriovorus HD100 guards against Pseudomonas tolaasii brown-blotch lesions on the surface of post-harvest Agaricus bisporus supermarket mushrooms

BACKGROUND: Pseudomonas tolaasii is a problematic pathogen of cultured mushrooms, forming dark brown 'blotches' on mushroom surfaces and causing spoilage during crop growth and post-harvest . Treating P. tolaasii infection is difficult, as other, commensal bacterial species such as Pseudomonas putida are necessary for mushroom growth, so treatments must be relatively specific. RESULTS: We have found that P. tolaasii is susceptible to predation in vitro by the δ-proteobacterium Bdellovibrio bacteriovorus. This effect also occurred in funga, where B. bacteriovorus was administered to post-harvest mushroom caps before and after administration of the P. tolaasii pathogen. A significant, visible improvement in blotch appearance, after incubation, was observed on administration of Bdellovibrio. A significant reduction in viable P. tolaasii cell numbers, recovered from the mushroom tissue, was detected. This was accompanied by a more marked reduction in blotch severity on Bdellovibrio administration. We found that there was in some cases an accompanying overgrowth of presumed-commensal, non-Pseudomonas bacteria on post-harvest mushroom caps after Bdellovibrio-treatment. These bacteria were identified (by 16SrRNA gene sequencing) as Enterobacter species, which were seemingly resistant to predation. We visualised predatory interactions occuring between B. bacteriovorus and P. tolaasii on the post-harvest mushroom cap surface by Scanning Electron Microscopy, seeing predatory invasion of P. tolaasii by B. bacteriovorus in funga. This anti-P. tolaasii effect worked well in post-harvest supermarket mushrooms, thus Bdellovibrio was not affected by any pre-treatment of mushrooms for commercial/consumer purposes. CONCLUSIONS: The soil-dwelling B. bacteriovorus HD100 preys upon and kills P. tolaasii, on mushroom surfaces, and could therefore be applied to prevent spoilage in post-harvest situations where mushrooms are stored and packaged for sale

Nonlinear Optical Waveguide Devices in GaAs/AlGaAs

This thesis is concerned with the design, characterisation and implementation of an all-optical logic waveguide device. Operation of such a device depends crucially on the fact that it includes a nonlinear material whose refractive index changes if it is subjected to sufficiently intense optical excitation. (This intensity dependance of the refractive index is often expressed by the relation n= no+ n2l, where no is the low intensity refractive index, n2 is the nonlinear coefficient, and I is the intensity of the incident optical radiation.) The optically induced variation in the refractive index is transformed into a nonlinearity in the device transmission by use of certain waveguide properties thus enabling the device to perform all-optical logic operations. The particular work in this thesis concentrates on the Asymmetric Mach-Zehnder Interferometer (AMZI) which is described in Chapter One. The nonlinear material used in this thesis is AlxGa1-xAs because (i), waveguide fabrication technology in this material is well established and reliable, and (ii), the material has a significant optical nonlinearity easily accessible with laser radiation. The thesis begins by introducing nonlinear optical waveguide devices. Chapter Two then reviews the various optical nonlinearities in semiconductors and presents the current theoretical models available for the description of these effects. Chapter Three describes the nonlinear waveguide design process. Included in this chapter are considerations which have to be made for the attainment of optimum optical nonlinear effects. Chapter Four contains the device fabrication details and describes the considerations made during device production. The results of linear and nonlinear characterisation of waveguides are presented in Chapter Five where descriptions of the various experimental details are also given. The Asymmetric Mach Zehnder Interferometer is then examined in Chapter Six where results of both the theoretical and experimental studies are presented. Finally, in Chapter Seven, the conclusions are presented and suggestions for future work are given

Common decisions made and actions taken during small-animal consultations at eight first-opinion practices in the United Kingdom

In order for veterinary surgeons to undertake an evidence-based approach to making decisions about theirpatients, it is important that new evidence is generated to support the clinical decision-making process.Many of the decisions are likely to be around the actions taken to treat or manage health problemsdiscussed during the consultation, and little is currently known about the factors which affect the typeof action taken. The aim of this study was to determine the decisions made and actions taken for healthproblems discussed during first-opinion small-animal consultations, as well as identifying factors whichmay affect the decision-making process.Data were gathered during direct observation of small-animal consultations conducted by 62 veterinarysurgeons in eight first-opinion practices in the United Kingdom. For each patient presented, data weregathered on all health problems discussed during the consultation. The decision made (whether an actionwas taken or not) and the action taken where applicable (e.g. therapeutic treatment with antibiotics) wasalso recorded. A three-level multivariable logistic-regression model was developed, with problem (Level1) nested within patient (Level 2) nested within consulting veterinary surgeon (Level 3), and a binaryoutcome variable of action versus no action.At least one action was taken for 69% (n = 2203/3192) of all problems discussed. Therapeutic treatmentwas the most common action taken (n = 1286/3192 problems; 40.3%), followed by management advice(n = 1040/3192; 32.6%) and diagnostic work-up (n = 323/3192; 10.1%). The most common therapeutictreatment was antibiotics (n = 386/1286; 30%), while the most common management advice given wasdietary advice (n = 509/1040; 48.9%). The three explanatory variables remaining in the final model werewhether the problem was a presenting or non-presenting problem, the type of diagnosis made, andthe body system affected. Explanatory variables which did not remain in the final model were patientsignalment, problem history, consultation type, clinical examination type, and who raised the problem(veterinary surgeon or owner).For over two-thirds of problems discussed, an action was taken which suggests these problems maybe seen as important by the veterinary surgeon and/or pet owner. No action was taken for almost a thirdof cases which could represent ‘watchful waiting’, which has been highlighted as important in humanhealthcare. Future research should focus on the common actions taken, further exploring the complexdecision-making process, and examining the effect of the decisions made on long-term patient outcomes

Co-Release of GABA Does Not Occur at Glycinergic Synapses onto Lumbar Motoneurons in Juvenile Mice

The fast inhibitory neurotransmitters glycine and GABA are co-localized in synaptic terminals of inhibitory interneurons in the spinal cord and co-released onto lumbar motoneurons in neonatal rats. We performed whole-cell voltage-clamp experiments on spinal cord preparations obtained from juvenile (P8–14) mice to determine whether inhibitory currents exhibited GABAergic components in motoneurons of animals of weight-bearing age. Subsequently we established whether or not GABA is co-released at glycinergic synapses onto motoneurons by determining if it conferred modulatory effects on the kinetics of glycinergic currents. Exponential fitting analysis showed that evoked and miniature inhibitory post-synaptic currents (IPSCs) were best-fitted with a single decay time constant. Responses recorded from connected interneuron-motoneuron pairs showed no effect of a benzodiazepine or a GABAA receptor antagonist. Similarly IPSCs evoked by extracellular stimulation and miniature IPSCs were not affected by either agent, indicating the absence of co-detection. Experimental manipulation of the relative content of pre-synaptic GABA and glycine conferred no effect on post-synaptic responses. It is thus unlikely that GABA is co-released in biologically relevant amounts at glycinergic synapses onto lumbar motoneurons in mice of this age

Proximal and distal spinal neurons innervating multiple synergist and antagonist motor pools

Motoneurons control muscle contractions, and their recruitment by premotor circuits is tuned to produce accurate motor behaviours. To understand how these circuits coordinate movement across and between joints, it is necessary to understand whether spinal neurons pre-synaptic to motor pools have divergent projections to more than one motoneuron population. Here, we used modified rabies virus tracing in mice to investigate premotor INs projecting to synergist flexor or extensor motoneurons, as well as those projecting to antagonist pairs of muscles controlling the ankle joint. We show that similar proportions of premotor neurons diverge to synergist and antagonist motor pools. Divergent premotor neurons were seen throughout the spinal cord, with decreasing numbers but increasing proportion with distance from the hindlimb enlargement. In the cervical cord, divergent long descending propriospinal neurons were found in contralateral lamina VIII, had large somata, were neither glycinergic, nor cholinergic, and projected to both lumbar and cervical motoneurons. We conclude that distributed spinal premotor neurons coordinate activity across multiple motor pools and that there are spinal neurons mediating co-contraction of antagonist muscles

Examining Multisystem Inflammatory Syndrome in Children (MIS-C) Amidst the SARS-CoV-2 Pandemic

Background/Objective: Multisystem Inflammatory Syndrome in Children (MIS-C) is a novel and rare pediatric post-infectious complication associated with SARS-CoV-2 infection. First described in April 2020, our scope of understanding is limited but rapidly growing. Our objective was to construct a literature repository containing MIS-C patient data from available publications to serve as a curated collection of literature on the topic. This collection facilitates direct comparison of data from various sources, allowing for informed discussions of MIS-C.    Methods: A database search strategy was developed for locating primary literature on MIS-C available on PubMed, medRxiv, and bioRxiv databases. Literature searches were conducted from June 26, 2020 to July 10, 2020. Search results were tested against several criteria before inclusion in the repository. Intrinsic limitations for each publication were identified during quality review. Data from each source was organized in a standardized format for analysis.   Results: 26 publications met inclusion criteria, 9 (35%) in pre-print status. 742 cases of probable or confirmed MIS-C were reported. Individuals ranged from 7 months to 20 years old and 58% were male. By SARS-CoV-2 PCR testing, 257/707 (36%) were positive while 485/597 (81%) were positive by SARS-CoV-2 serology testing. Common presenting symptoms included fever, one or more gastrointestinal symptoms, and rash. Laboratory testing varied, but elevated C-Reactive Protein was the most common finding (411/689, 60%), followed by elevated D-Dimer (214/470, 46%). Echocardiogram findings included coronary artery dilation in 38/414 (9%) and decreased ejection fraction in 177/330 (54%). Treatments offered included intravenous immunoglobulin (486/742, 65%), followed by steroids (376/742, 51%). 450/577 (78%) required ICU care. Patient outcomes were generally favorable, with 11 (1%) fatalities at the time of publication.  Conclusion/Impact: Our repository of MIS-C literature compiled patient reports to identify common clinical presentations and laboratory findings. Future literature reviews are necessary to elucidate mechanisms associated with MIS-C and establish diagnostic criteria.&nbsp

Examining Multisystem Inflammatory Syndrome in Children (MIS-C) Amidst the SARS-CoV-2 Pandemic

Background/Objective: Multisystem Inflammatory Syndrome in Children (MIS-C) is a novel and rare pediatric postinfectious complication associated with SARS-CoV-2 infection. First described in April 2020, our scope of understanding is limited but rapidly growing. Our objective was to construct a literature repository containing MIS-C patient data from available publications to serve as a curated collection of literature on the topic. This collection facilitates direct comparison of data from various sources, allowing for informed discussions of MIS-C. Methods: A database search strategy was developed for locating primary literature on MIS-C available on PubMed, medRxiv, and bioRxiv databases. Literature searches were conducted from June 26, 2020 to July 10, 2020. Search results were tested against several criteria before inclusion in the repository. Intrinsic limitations for each publication were identified during quality review. Data from each source was organized in a standardized format for analysis. Results: 26 publications met inclusion criteria, with 9 (35%) in pre-print status. 742 cases of probable or confirmed MIS-C were reported. Individuals ranged from 7 months to 20 years old and 58% were male. By SARS-CoV-2 PCR testing, 257/707 (36%) were positive while 485/597 (81%) were positive by SARS-CoV-2 serology testing. Common presenting symptoms included fever, one or more gastrointestinal symptoms, and rash. Laboratory testing varied, but elevated C-Reactive Protein was the most common finding (411/689, 60%), followed by elevated D-Dimer (214/470, 46%). Echocardiogram findings included coronary artery dilation in 38/414 (9%) and decreased ejection fraction in 177/330 (54%). Treatments offered included intravenous immunoglobulin (486/742, 65%), followed by steroids (376/742, 51%). 450/577 (78%) requiredICU care. Patient outcomes were generally favorable, with 11 (1%) fatalities at the time of publication. Conclusion/Impact: Our repository of MIS-C literature compiled patient reports to identify common clinical presentations and laboratory findings. Future literature reviews are necessary to elucidate mechanisms associated with MIS-C and establish diagnostic criteria

Multivariate proteomic profiling identifies novel accessory proteins of coated vesicles.

Despite recent advances in mass spectrometry, proteomic characterization of transport vesicles remains challenging. Here, we describe a multivariate proteomics approach to analyzing clathrin-coated vesicles (CCVs) from HeLa cells. siRNA knockdown of coat components and different fractionation protocols were used to obtain modified coated vesicle-enriched fractions, which were compared by stable isotope labeling of amino acids in cell culture (SILAC)-based quantitative mass spectrometry. 10 datasets were combined through principal component analysis into a "profiling" cluster analysis. Overall, 136 CCV-associated proteins were predicted, including 36 new proteins. The method identified >93% of established CCV coat proteins and assigned >91% correctly to intracellular or endocytic CCVs. Furthermore, the profiling analysis extends to less well characterized types of coated vesicles, and we identify and characterize the first AP-4 accessory protein, which we have named tepsin. Finally, our data explain how sequestration of TACC3 in cytosolic clathrin cages causes the severe mitotic defects observed in auxilin-depleted cells. The profiling approach can be adapted to address related cell and systems biological questions