1,250 research outputs found
Discovery, cloning, and analysis of novel fluorescent proteins from various color morphs of Corynactis californica
Although the number of fluorescent protein (FP) genes cloned from the GFP family continues to increase, few studies of GFP-type pigments in non-bioluminescent, non-symbiotic organisms have been attempted. The first goal of this study was to locate, clone, characterize, and analyze fluorescent proteins from an organism exhibiting these traits in order to better understand their evolution and function. I successfully cloned two full-length GFP homologs by applying a FACS-based screening method to a cDNA library constructed from a temperate corallimorpharian, Corynactis californica. The full-length coding regions of each gene were subcloned into an expression vector and bacterial cultures were used to express the proteins. Spectral properties of purified proteins were characterized and chromophore maturation behavior was examined. Phylogenetic methods were also used to analyze the new gene sequences in relation to homologous GFP family members. After discovering two GFP-like proteins in a single red morph, I investigated six additional morphs of Corynactis californica, and found indications of a variety of fluorescent pigments based on fluorescence emission spectra from live specimens. The second goal of this study was to identify and describe the variation in fluorescent pigments among morphs of C. californica and to relate the in vivo emission patterns and colors to FP genes cloned from and expressed in each morph. Specifically, I found that all morphs express a similar suite of GFP-like proteins, generated by at least three to four genetic loci, which code for three colors: green, orange, and red. The genes exhibit tissue-specific expression patterns that differ by morph, and two major expression patterns emerged. Sequence and phylogenetic analyses comparing the new FP genes from C. californica to one another and to homologous members of the GFP family indicate that FP genes from this species are most closely related to one another, but that FP genes arose in an ancestor to the Anthozoa before speciation events separating anthozoan subclasses, including the Corallimorpharia. Possible ecological roles of variations in fluorescent pigmentation among morphs of C. californica are also discussed
Evaluation of Recent Upgrades to the NESS (Nuclear Engine System Simulation) Code
The Nuclear Thermal Rocket (NTR) concept is being evaluated as a potential propulsion technology for exploratory expeditions to the moon, Mars, and beyond. The need for exceptional propulsion system performance in these missions has been documented in numerous studies, and was the primary focus of a considerable effort undertaken during the Rover/NERVA program from 1955 to 1973. The NASA Glenn Research Center is leveraging this past NTR investment in their vehicle concepts and mission analysis studies with the aid of the Nuclear Engine System Simulation (NESS) code. This paper presents the additional capabilities and upgrades made to this code in order to perform higher fidelity NTR propulsion system analysis and design, and a comparison of its results to the Small Nuclear Rocket Engine (SNRE) design
A Comparison of Materials Issues for Cermet and Graphite-Based NTP Fuels
This paper compares material issues for cermet and graphite fuel elements. In particular, two issues in NTP fuel element performance are considered here: ductile to brittle transition in relation to crack propagation, and orificing individual coolant channels in fuel elements. Their relevance to fuel element performance is supported by considering material properties, experimental data, and results from multidisciplinary fluid/thermal/structural simulations. Ductile to brittle transition results in a fuel element region prone to brittle fracture under stress, while outside this region, stresses lead to deformation and resilience under stress. Poor coolant distribution between fuel element channels can increase stresses in certain channels. NERVA fuel element experimental results are consistent with this interpretation. An understanding of these mechanisms will help interpret fuel element testing results
Multidisciplinary Simulation of Graphite-Composite and Cermet Fuel Elements for NTP Point of Departure Designs
This paper compares the expected performance of two Nuclear Thermal Propulsion fuel types. High fidelity, fluid/thermal/structural + neutronic simulations help predict the performance of graphite-composite and cermet fuel types from point of departure engine designs from the Nuclear Thermal Propulsion project. Materials and nuclear reactivity issues are reviewed for each fuel type. Thermal/structural simulations predict thermal stresses in the fuel and thermal expansion mis-match stresses in the coatings. Fluid/thermal/structural/neutronic simulations provide predictions for full fuel elements. Although NTP engines will utilize many existing chemical engine components and technologies, nuclear fuel elements are a less developed engine component and introduce design uncertainty. Consequently, these fuel element simulations provide important insights into NTP engine performance
Field evaluation of the efficacy and safety of a combination of spinosad and milbemycin oxime in the treatment and prevention of naturally acquired flea infestations and treatment of intestinal nematode infections in dogs in Europe
AbstractTwo separate randomised, blinded, multicentre field trials were conducted to evaluate the efficacy and safety of a combination of spinosad and milbemycin oxime (MO) (Trifexis®, Elanco Animal Health) in the treatment and prevention of naturally acquired flea infestations and intestinal nematode infections in European dogs. Treatments using Trifexis® and each control veterinary product (CVP) were administered once on Day 0 in both field studies.In the flea field trial, 11 veterinary clinics in France participated in the study. On Day 0, whole body flea comb counts were conducted on all dogs being evaluated for enrolment. Dogs with ≥7 fleas on Day 0 were enrolled, treated once on Day 0 with spinosad/MO or the CVP (Stronghold®; selamectin) and then underwent post-treatment flea counts on Days 14 and 30. There were 150 spinosad/MO treated dogs and 71 CVP treated dogs included in the flea effectiveness population. Effectiveness against fleas (% reduction in geometric means; GM) was 98.97% and 97.37% for the spinosad/MO treated dogs, and 97.43% and 93.96% for the CVP dogs on Days 14 and 30, respectively, compared to the pre-treatment baseline flea counts. Of the spinosad/MO dogs, 89.3% and 80.0% had no live fleas on Days 14 and 30, compared to 77.5% and 70.4% of the CVP dogs, respectively.In the nematode field trial, data from 10 veterinary clinics in France and 19 in Ireland were pooled. Faecal samples from dogs at each clinic were analysed. A positive result at screening (parasite eggs from Toxocara canis, Toxascaris leonina, Trichuris vulpis or Ancylostoma caninum) allowed for enrolment. Dogs were randomised to spinosad/MO or the CVP (Milbemax®; MO/praziquantel). On Day 8, a post-treatment faecal sample was taken and analysed. Of 2333 dogs screened for nematode eggs, 238 dogs were positive with one or more of these nematodes, and 229 were enrolled in the study. Of the 229 dogs, 151 were treated with a single dose of spinosad/MO, and 77 were treated with a single dose of CVP. Post-treatment effectiveness against all nematodes (% reduction GM) was achieved with reductions of 98.57% and 97.57% for the spinosad/MO treated dogs and CVP dogs, respectively, as compared to the pre-treatment baseline faecal egg counts.Trifexis® was shown to be safe and effective against natural infestations of fleas as well as mixed and single intestinal nematode infections in client owned dogs in Europe when administered as a single oral administration at the recommended dose
Revised Point of Departure Design Options for Nuclear Thermal Propulsion
In an effort to further refine potential point of departure nuclear thermal rocket engine designs, four proposed engine designs representing two thrust classes and utilizing two different fuel matrix types are designed and analyzed from both a neutronics and thermodynamic cycle perspective. Two of these nuclear rocket engine designs employ a tungsten and uranium dioxide cermet (ceramic-metal) fuel with a prismatic geometry based on the ANL-200 and the GE-710, while the other two designs utilize uranium-zirconium-carbide in a graphite composite fuel and a prismatic fuel element geometry developed during the Rover/NERVA Programs. Two engines are analyzed for each fuel type, a small criticality limited design and a 111 kN (25 klbf) thrust class engine design, which has been the focus of numerous manned mission studies, including NASA's Design Reference Architecture 5.0. slightly higher T/W ratios, but they required substantially more 235U
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Cnidofest 2018: the future is bright for cnidarian research.
The 2018 Cnidarian Model Systems Meeting (Cnidofest) was held September 6-9th at the University of Florida Whitney Laboratory for Marine Bioscience in St. Augustine, FL. Cnidofest 2018, which built upon the momentum of Hydroidfest 2016, brought together research communities working on a broad spectrum of cnidarian organisms from North America and around the world. Meeting talks covered diverse aspects of cnidarian biology, with sessions focused on genomics, development, neurobiology, immunology, symbiosis, ecology, and evolution. In addition to interesting biology, Cnidofest also emphasized the advancement of modern research techniques. Invited technology speakers showcased the power of microfluidics and single-cell transcriptomics and demonstrated their application in cnidarian models. In this report, we provide an overview of the exciting research that was presented at the meeting and discuss opportunities for future research
TG-DTA and DSC investigations of ''pinhão'' starch modified by calcium hypochlorite and UV light.
Starches, when in its native forms, usually do not have the characteristics required for industrial processing. ''Pinhão'', a seed from the Araucaria angustifolia tree, has starch as main presenting as a great alternative source of starch. Samples of native ''pinhão'' starch were treated with standard calcium hypochlorite solutions (0.1, 0.2 and 0.5 mol L-1) and exposed for one hour under UV light. The modification process applied altered the thermal behavior of the ''pinhão'' starch as the TGA-DTA and DSC results presented.Edição dos Anais do 7º Simpósio de Análise Térmica, 2015, Bauru
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Temperature stress, gene expression, and innate immunity at the onset of cnidarian-dinoflagellate symbiosis
The intracellular mutualism between cnidarians and photosynthetic dinoflagellates (genus Symbiodinium) is responsible for the physical and trophic structure of diverse coral reef ecosystems. This relationship, based on nutrient exchange, allows for high productivity in tropical waters, which are generally nutrient-poor environments. Numerous environmental stressors currently threaten the health of corals, most notably elevated seawater temperatures due to global climate change, many of which can cause coral bleaching, or symbiosis collapse. Despite this, relatively little is known about the mechanisms underpinning the onset and maintenance of the association. In this dissertation, I studied the onset of cnidarian-dinoflagellate symbiosis using ecological, molecular, and genomic approaches.
First, I examined effects of elevated seawater temperature on coral larvae (Fungia scutaria) during the period of symbiosis establishment (Chapter 2). I found that larvae exposed to a 2-4°C increase in temperature were significantly impaired in their ability to form the symbiosis. These results are the first to quantify the effect of elevated temperature on coral symbiosis onset and are important in light of projected increases in seawater temperatures.
Next, I created a cDNA microarray from non-symbiotic and newly symbiotic F.
scutaria larvae to identify host transcripts that were differentially expressed in response to symbiosis onset (Chapter 3). Analyses revealed very few changes in the larval transcriptome as a result of infection with its homologous symbiont. I hypothesize that Symbiodinium sp. has evolved mechanisms to suppress or circumvent cnidarian host responses to colonization similar to those seen in the invasion of animal cells by protozoan parasites.
Finally, I explored a family of genes (tumor necrosis factor receptor associated factors, or TRAFs), which are key signal transducers in pro-inflammatory innate immune pathways, in cnidarian genomes (Chapter 4). Phylogenetic analyses identified 8 major lineages of TRAFs, including 3 new subfamilies, each with cnidarian TRAF sequences, indicating that the TRAF gene family was fully diversified prior to the divergence between cnidarians and bilaterians. I also cloned TRAF6-like genes from two model symbiotic cnidarians, Aiptasia pallida and F. scutaria, laying the groundwork for future functional studies that can examine the role of TRAF6 in cnidarian immunity, and a possible role for TRAF6 in regulating cnidarian-dinoflagellate mutualisms
Induced effects of oxidation with potassium permanganate in the modification of corn starch.
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