30 research outputs found

    Mechanisms of axial polarity modification during postembryonic development of the basal bilaterian Convolutriloba macropyga

    Get PDF
    Acoel flatworms have varied modes of asexual reproduction that involve dramatic postembryonic modification of their anterior-posterior (AP) axis. The acoel species Convolutriloba macropyga reproduces through a reversed polarity budding process in which offspring develop from two posterior budding sites with a complete reversal of the AP axis compared to the parent. Reversed polarity budding is preceded by the development of a zone of tissue with disorganized musculature that is incapable of regeneration, suggesting a transient loss of axis polarity at each budding site. For this reason, these tissues are titled the polarity transition zone (PTZ). While this alteration of existing axial polarity seems to be required for subsequent reversal of the AP axis in the budding progeny, the mechanisms that allow for temporary axis modification and reversal are not known. Wnt, Hedgehog, and other signal transduction pathways have conserved roles in AP axis development and reestablishment during both metazoan embryogenesis and regeneration, suggesting these signals may function in mediating changes in axis polarity during budding in C. macropyga. Here, we have used a pharmacological screen to perturb conserved signaling pathways in Convolutriloba tissues and observed loss of axial polarity in tissues exposed to inhibitors of the Hedgehog pathway. Given the putative role of Hedgehog signal transduction in mediating alterations in axial polarity during budding, we have quantified changes in the expression of Hedgehog signaling components and regulators in budding tissues using qPCR. Hedgehog signaling was downregulated within the PTZ when compared to neighboring polarized tissues. RNAi mediated knockdown of Hedgehog gene products resulted in phenotypes of delayed bud detachment and failure to initiate future budding events. These data support Hedgehog as a key signaling pathway involved in the modification of AP axis polarity during asexual reproduction and may provide key insights towards better understanding the evolution of asexual reproduction strategies in other taxa

    Community structure of soil fungi in a novel perennial crop monoculture, annual agriculture, and native prairie reconstruction

    Get PDF
    The use of perennial crop species in agricultural systems may increase ecosystem services and sustainability. Because soil microbial communities play a major role in many processes on which ecosystem services and sustainability depend, characterization of soil community structure in novel perennial crop systems is necessary to understand potential shifts in function and crop responses. Here, we characterized soil fungal community composition at two depths (0–10 and 10–30 cm) in replicated, long-term plots containing one of three different cropping systems: a tilled three-crop rotation of annual crops, a novel perennial crop monoculture (Intermediate wheatgrass, which produces the grain Kernza®), and a native prairie reconstruction. The overall fungal community was similar under the perennial monoculture and native vegetation, but both were distinct from those in annual agriculture. The mutualist and saprotrophic community subsets mirrored differences of the overall community, but pathogens were similar among cropping systems. Depth structured overall communities as well as each functional group subset. These results reinforce studies showing strong effects of tillage and sampling depth on soil community structure and suggest plant species diversity may play a weaker role. Similarities in the overall and functional fungal communities between the perennial monoculture and native vegetation suggest Kernza® cropping systems have the potential to mimic reconstructed natural systems

    New Insights into Fluoroquinolone Resistance in Mycobacterium tuberculosis: Functional Genetic Analysis of gyrA and gyrB Mutations

    Get PDF
    Fluoroquinolone antibiotics are among the most potent second-line drugs used for treatment of multidrug-resistant tuberculosis (MDR TB), and resistance to this class of antibiotics is one criterion for defining extensively drug resistant tuberculosis (XDR TB). Fluoroquinolone resistance in Mycobacterium tuberculosis has been associated with modification of the quinolone resistance determining region (QRDR) of gyrA. Recent studies suggest that amino acid substitutions in gyrB may also play a crucial role in resistance, but functional genetic studies of these mutations in M. tuberculosis are lacking. In this study, we examined twenty six mutations in gyrase genes gyrA (seven) and gyrB (nineteen) to determine the clinical relevance and role of these mutations in fluoroquinolone resistance. Transductants or clinical isolates harboring T80A, T80A+A90G, A90G, G247S and A384V gyrA mutations were susceptible to all fluoroquinolones tested. The A74S mutation conferred low-level resistance to moxifloxacin but susceptibility to ciprofloxacin, levofloxacin and ofloxacin, and the A74S+D94G double mutation conferred cross resistance to all the fluoroquinolones tested. Functional genetic analysis and structural modeling of gyrB suggest that M330I, V340L, R485C, D500A, D533A, A543T, A543V and T546M mutations are not sufficient to confer resistance as determined by agar proportion. Only three mutations, N538D, E540V and R485C+T539N, conferred resistance to all four fluoroquinolones in at least one genetic background. The D500H and D500N mutations conferred resistance only to levofloxacin and ofloxacin while N538K and E540D consistently conferred resistance to moxifloxacin only. Transductants and clinical isolates harboring T539N, T539P or N538T+T546M mutations exhibited low-level resistance to moxifloxacin only but not consistently. These findings indicate that certain mutations in gyrB confer fluoroquinolone resistance, but the level and pattern of resistance varies among the different mutations. The results from this study provide support for the inclusion of the QRDR of gyrB in molecular assays used to detect fluoroquinolone resistance in M. tuberculosis

    La Grange Comprehensive Plan 2018 - 2038

    Get PDF
    In the Fall of 2017, the City of La Grange and Texas Target Communities partnered to create a task force to represent the community. The task force was integral to the planning process, contributing the thoughts, desires, and opinions of community members—as well as their enthusiasm about La Grange’s future. This fifteen-month planning process ended in August 2018. The result of this collaboration is the La Grange Comprehensive Plan, which is the official policy guide for the community’s growth over the next twenty years.La Grange Comprehensive Plan 2018 - 2038 provides a guide for the future growth of the City. This document was developed by Texas Target Communities in partnership with the City of La Grange.Texas Target Communitie

    Empirical Legal Studies Before 1940: A Bibliographic Essay

    Get PDF
    The modern empirical legal studies movement has well-known antecedents in the law and society and law and economics traditions of the latter half of the 20th century. Less well known is the body of empirical research on legal phenomena from the period prior to World War II. This paper is an extensive bibliographic essay that surveys the English language empirical legal research from approximately 1940 and earlier. The essay is arranged around the themes in the research: criminal justice, civil justice (general studies of civil litigation, auto accident litigation and compensation, divorce, small claims, jurisdiction and procedure, civil juries), debt and bankruptcy, banking, appellate courts, legal needs, legal profession (including legal education), and judicial staffing and selection. Accompanying the essay is an extensive bibliography of research articles, books, and reports

    In the groove: American rock criticism, 1966-1978

    No full text
    Thesis (Ph. D.)--University of Rochester. Department of History, 2017.Rock and roll music was a national youth obsession for a dozen years before the first rock critics began writing seriously about the form. Rock was dismissed by adult cultural authorities as empty, degraded, and even dangerous. However, to its fans, rock was an important form of personal expression, a source of group identity, and a mode of political discourse. Rock critics understood its cultural and political power. In their work, they explained its importance to the American public. In 1966, the first rock critic, Richard Goldstein, began writing about rock and roll in a weekly column in the Village Voice called “Pop Eye.” In it, he asserted that rock and roll was an art that deserved the same recognition and protections afforded to other art forms. By 1967, The New Yorker hired Ellen Willis to write about rock in a regular column called “Rock, Etc.” She brought an intellectual sophistication to the genre that would resound long after her career as a rock critic ended. Later in 1967, Rolling Stone debuted; it would become the most visible and influential source of rock criticism for the next fifty years. Editor Jann Wenner’s tastes and approach would affect the way rock was perceived in his own time and for decades after. Finally, in 1968, Lester Bangs debuted onto the scene, writing artful reviews for publications like Creem and Rolling Stone, explaining the changes that were taking place as rock music splintered into subgenres like punk and heavy metal. The quality of these rock critics’ thought and the influence of their writing makes rock criticism an important and under-studied branch of Sixties literature. Each of the rock critics addressed in this dissertation explained to the public what rock music meant and why it mattered. By placing rock in its social, political, and cultural context, they demonstrated that it was far from the empty form cultural authorities thought it was. Their work permanently changed perceptions of popular music, proving that it was substantial enough to stand up to the same kind of critical treatment as other art forms

    Community structure of soil fungi in a novel perennial crop monoculture, annual agriculture, and native prairie reconstruction.

    No full text
    The use of perennial crop species in agricultural systems may increase ecosystem services and sustainability. Because soil microbial communities play a major role in many processes on which ecosystem services and sustainability depend, characterization of soil community structure in novel perennial crop systems is necessary to understand potential shifts in function and crop responses. Here, we characterized soil fungal community composition at two depths (0-10 and 10-30 cm) in replicated, long-term plots containing one of three different cropping systems: a tilled three-crop rotation of annual crops, a novel perennial crop monoculture (Intermediate wheatgrass, which produces the grain Kernza®), and a native prairie reconstruction. The overall fungal community was similar under the perennial monoculture and native vegetation, but both were distinct from those in annual agriculture. The mutualist and saprotrophic community subsets mirrored differences of the overall community, but pathogens were similar among cropping systems. Depth structured overall communities as well as each functional group subset. These results reinforce studies showing strong effects of tillage and sampling depth on soil community structure and suggest plant species diversity may play a weaker role. Similarities in the overall and functional fungal communities between the perennial monoculture and native vegetation suggest Kernza® cropping systems have the potential to mimic reconstructed natural systems

    Evaluation of the TB-Biochip Oligonucleotide Microarray System for Rapid Detection of Rifampin Resistance in Mycobacterium tuberculosis

    No full text
    The TB-Biochip oligonucleotide microarray system is a rapid system to detect mutations associated with rifampin (RIF) resistance in mycobacteria. After optimizing the system with 29 laboratory-generated rifampin-resistant mutants of Mycobacterium tuberculosis, we evaluated the performance of this test using 75 clinical isolates of Mycobacterium tuberculosis. With this small sample set, the TB-Biochip system displayed a sensitivity of 80% and a specificity of 100% relative to conventional drug susceptibility testing results for RIF resistance. For these samples (∼50% tested positive), the positive predictive value was 100% and the negative predictive value was 85%. Four of the seven observed discrepancies were attributed to rare and new mutations not represented in the microarray, while three of the strains with discrepant results did not carry mutations in the RIF resistance-determining region. The results of this study confirm the utility of the system for rapid detection of RIF resistance and suggest approaches to increasing its sensitivity
    corecore