Synthetic and Evolutionary Construction of a Chlorate-Reducing Shewanella oneidensis MR-1.

UnlabelledDespite evidence for the prevalence of horizontal gene transfer of respiratory genes, little is known about how pathways functionally integrate within new hosts. One example of a mobile respiratory metabolism is bacterial chlorate reduction, which is frequently encoded on composite transposons. This implies that the essential components of the metabolism are encoded on these mobile elements. To test this, we heterologously expressed genes for chlorate reduction from Shewanella algae ACDC in the non-chlorate-reducing Shewanella oneidensis MR-1. The construct that ultimately endowed robust growth on chlorate included cld, a cytochrome c gene, clrABDC, and two genes of unknown function. Although strain MR-1 was unable to grow on chlorate after initial insertion of these genes into the chromosome, 11 derived strains capable of chlorate respiration were obtained through adaptive evolution. Genome resequencing indicated that all of the evolved chlorate-reducing strains replicated a large genomic region containing chlorate reduction genes. Contraction in copy number and loss of the ability to reduce chlorate were also observed, indicating that this phenomenon was extremely dynamic. Although most strains contained more than six copies of the replicated region, a single strain with less duplication also grew rapidly. This strain contained three additional mutations that we hypothesized compensated for the low copy number. We remade the mutations combinatorially in the unevolved strain and determined that a single nucleotide polymorphism (SNP) upstream of cld enabled growth on chlorate and was epistatic to a second base pair change in the NarP binding sequence between narQP and nrfA that enhanced growth.ImportanceThe ability of chlorate reduction composite transposons to form functional metabolisms after transfer to a new host is an important part of their propagation. To study this phenomenon, we engineered Shewanella oneidensis MR-1 into a chlorate reducer. We defined a set of genes sufficient to endow growth on chlorate from a plasmid, but found that chromosomal insertion of these genes was nonfunctional. Evolution of this inoperative strain into a chlorate reducer showed that tandem duplication was a dominant mechanism of activation. While copy number changes are a relatively rapid way of increasing gene dosage, replicating almost 1 megabase of extra DNA is costly. Mutations that alleviate the need for high copy number are expected to arise and eventually predominate, and we identified a single nucleotide polymorphism (SNP) that relieved the copy number requirement. This study uses both rational and evolutionary approaches to gain insight into the evolution of a fascinating respiratory metabolism

Developing a Self-Assessment Package for Members to Comply with the FPA Australia Code of Practice

Fire Protection Association (FPA) Australia is a non-profit organization committed to fire safety. Through their Code of Practice (COP), FPA Australia encourages ethical business practices of its member companies in the fire protection industry. This project proposes a self-assessment system to aid FPA Australia in increasing compliance with the COP. This was accomplished by obtaining member opinions of the COP and by designing a prototype self-assessment package

Immunocompetent murine models for the study of glioblastoma immunotherapy.

Glioblastoma remains a lethal diagnosis with a 5-year survival rate of less than 10%. (NEJM 352:987-96, 2005) Although immunotherapy-based approaches are capable of inducing detectable immune responses against tumor-specific antigens, improvements in clinical outcomes are modest, in no small part due to tumor-induced immunosuppressive mechanisms that promote immune escape and immuno-resistance. Immunotherapeutic strategies aimed at bolstering the immune response while neutralizing immunosuppression will play a critical role in improving treatment outcomes for glioblastoma patients. In vivo murine models of glioma provide an invaluable resource to achieving that end, and their use is an essential part of the preclinical workup for novel therapeutics that need to be tested in animal models prior to testing experimental therapies in patients. In this article, we review five contemporary immunocompetent mouse models, GL261 (C57BL/6), GL26 (C57BL/6) CT-2A (C57BL/6), SMA-560 (VM/Dk), and 4C8 (B6D2F1), each of which offer a suitable platform for testing novel immunotherapeutic approaches

In-situ measurements of the optical absorption of dioxythiophene-based conjugated polymers

Conjugated polymers can be reversibly doped by electrochemical means. This doping introduces new sub-bandgap optical absorption bands in the polymer while decreasing the bandgap absorption. To study this behavior, we have prepared an electrochemical cell allowing measurements of the optical properties of the polymer. The cell consists of a thin polymer film deposited on gold-coated Mylar behind which is another polymer that serves as a counterelectrode. An infrared transparent window protects the upper polymer from ambient air. By adding a gel electrolyte and making electrical connections to the polymer-on-gold films, one may study electrochromism in a wide spectral range. As the cell voltage (the potential difference between the two electrodes) changes, the doping level of the conjugated polymer films is changed reversibly. Our experiments address electrochromism in poly(3,4-ethylene-dioxy-thiophene) (PEDOT) and poly(3,4-dimethyl-propylene-dioxy-thiophene) (PProDOT-Me$_2$). This closed electrochemical cell allows the study of the doping induced sub-bandgap features (polaronic and bipolaronic modes) in these easily oxidized and highly redox switchable polymers. We also study the changes in cell spectra as a function of polymer thickness and investigate strategies to obtain cleaner spectra, minimizing the contributions of water and gel electrolyte features

Predictive Monitoring for Respiratory Decompensation Leading to Urgent Unplanned Intubation in the Neonatal Intensive Care Unit

Background: Infants admitted to the neonatal intensive care unit (NICU), and especially those born with very low birth weight (VLBW; \u3c 1,500 g), are at risk for respiratory decompensation requiring endotracheal intubation and mechanical ventilation. I ntubation and mechanical ventilation are associated with increased morbidity, particularly in urgent unplanned cases. Methods: We tested the hypothesis that the systemic response associated with respiratory decombensation can be detected from physiological monitoring and that statistical models of bedside monitoring data can identify infants at increased risk of urgent unplanned intubation. We studied 287 VLBW infants consecutively admitted to our NICU and found 96 events in 51 patients, excluding intUbations occurring within. 12h of a previous extubation. Results: In order of importance in a multivariable statistical model, we found that the characteristics of reduced O-2 satura, tion, especially as heart rate was falling; increased heart rate correlation with respiratory rate; and the amount of apnea were aIF significant independent pr,edictors.\u27 The predictive model, validated internally by bootStrap, had a receiver-operating characteristic area of 0.84 + / - 0.04. Conclusion: We propose that predictive monitoring in the NICU for urgent unplanned intubation may improve outcomes by allowing clinicians to intervene noninvasively before intubation is required

Surficial Geologic Map of the Charles City 7.5\u27 Quadrangle, Floyd County, IA

https://ir.uiowa.edu/igs_ofm/1126/thumbnail.jp

Asymmetric forest transition driven by the interaction of socioeconomic development and environmental heterogeneity in Central America

Forest transitions (FT) have been observed in many developed countries and more recently in the developing world. However, our knowledge of FT from tropical regions is mostly derived from case studies from within a particular country, making it difficult to generalize findings across larger regions. Here we overcome these difficulties by conducting a recent (2001-2010) satellite-based analysis of trends in forest cover across Central America, stratified by biomes, which we related to socioeconomic variables associated with human development. Results show a net decrease of woody vegetation resulting from 12,201 km2 of deforestation of moist forests and 6,825 km2 of regrowth of conifer and dry forests. The Human Development Index was the socioeconomic variable best associated with forest cover change. The least-developed countries, Nicaragua and Guatemala, experienced both rapid deforestation of moist forests and significant recovery of conifer and dry forests. In contrast, the most developed countries, Panama and Costa Rica, had net woody vegetation gain and amore stable forest cover configuration. These results imply a good agreement with FT predictions of forest change in relation to socioeconomic development, but strong asymmetry in rates and directions of change largely dependent upon the biomewhere change is occurring. The FT model should be refined by incorporating ecological and socioeconomic heterogeneity, particularly inmulticountry and regional studies. These asymmetric patterns of forest change should be evaluatedwhen developing strategies for conserving biodiversity and environmental services.Fil: Redo, Daniel J.. Universidad de Puerto Rico; Puerto RicoFil: Grau, Hector Ricardo. Universidad Nacional de Tucumán; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Aide, T. Mitchell. Universidad de Puerto Rico; Puerto RicoFil: Clark, Matthew L.. Sonoma State University; Estados Unido

Stochastic Modeling of Central Apnea Events in Preterm Infants

A near-ubiquitous pathology in very low birth weight infants is neonatal apnea, breathing pauses with slowing of the heart and falling blood oxygen. Events of substantial duration occasionally occur after an infant is discharged from the neonatal intensive care unit (NICU). It is not known whether apneas result from a predictable process or from a stochastic process, but the observation that they occur in seemingly random clusters justifies the use of stochastic models. We use a hidden-Markov model to analyze the distribution of durations of apneas and the distribution of times between apneas. The model suggests the presence of four breathing states, ranging from very stable (with an average lifetime of 12 h) to very unstable (with an average lifetime of 10 s). Although the states themselves are not visible, the mathematical analysis gives estimates of the transition rates among these states. We have obtained these transition rates, and shown how they change with post-menstrual age; as expected, the residence time in the more stable breathing states increases with age. We also extrapolated the model to predict the frequency of very prolonged apnea during the first year of life. This paradigm-stochastic modeling of cardiorespiratory control in neonatal infants to estimate risk for severe clinical events-may be a first step toward personalized risk assessment for life threatening apnea events after NICU discharge

Bedrock Geology of the New Haven 7.5\u27 Quadrangle, Mitchell County, Iowa

https://ir.uiowa.edu/igs_ofm/1119/thumbnail.jp