Innate Immunity in Fruit Flies: A Textbook Example of Genomic Recycling

Drosophila serve as a wonderful model for studying aspects of innate immunity, i.e. the physical, cellular, and molecular features that provide the first lines of defense against infections in flies and ma

Impact of cross-section uncertainties on supernova neutrino spectral parameter fitting in the Deep Underground Neutrino Experiment

A primary goal of the upcoming Deep Underground Neutrino Experiment (DUNE) is to measure the $\mathcal{O}(10)$ MeV neutrinos produced by a Galactic core-collapse supernova if one should occur during the lifetime of the experiment. The liquid-argon-based detectors planned for DUNE are expected to be uniquely sensitive to the $\nu_e$ component of the supernova flux, enabling a wide variety of physics and astrophysics measurements. A key requirement for a correct interpretation of these measurements is a good understanding of the energy-dependent total cross section $\sigma(E_\nu)$ for charged-current $\nu_e$ absorption on argon. In the context of a simulated extraction of supernova $\nu_e$ spectral parameters from a toy analysis, we investigate the impact of $\sigma(E_\nu)$ modeling uncertainties on DUNE's supernova neutrino physics sensitivity for the first time. We find that the currently large theoretical uncertainties on $\sigma(E_\nu)$ must be substantially reduced before the $\nu_e$ flux parameters can be extracted reliably: in the absence of external constraints, a measurement of the integrated neutrino luminosity with less than 10\% bias with DUNE requires $\sigma(E_\nu)$ to be known to about 5%. The neutrino spectral shape parameters can be known to better than 10% for a 20% uncertainty on the cross-section scale, although they will be sensitive to uncertainties on the shape of $\sigma(E_\nu)$. A direct measurement of low-energy $\nu_e$-argon scattering would be invaluable for improving the theoretical precision to the needed level.Comment: 25 pages, 21 figure

Measuring evolution acceptance using the GAENE: influences of gender, race, degree-plan, and instruction

Abstract Background The evolution education research community has defined the construct of “evolution acceptance” in different ways and measured it using different instruments. One of these instruments—the GAENE—has not been analyzed across different student populations, demographic groups, degree plans, and instructional treatments. Such comparisons are crucial for examining whether the inferences drawn from instrument measures are valid, reliable, and generalizable. In this study, we attempt to replicate findings produced in the original validation study and explore aspects of the instrument not previously examined. Methods We use Rasch analysis to study a large sample (n > 700) of undergraduates enrolled in standard introductory biology classes in the Northeastern USA. Participants completed the GAENE pre- and post-course for two semesters, and the MATE pre- and post-course for one semester. We assessed dimensionality, reliability, item fit, and rating scale functioning. We used regression analyses and generalized eta squared to evaluate the contribution of demographic and background variables to pre-course measures and pre-post course acceptance gains. Results Our analyses of GAENE dimensionality and item properties were generally in line with prior work, including the finding that particular items displayed psychometric problems. Surprisingly, GAENE measures did not differ between biology majors and non-majors. Evolution instruction produced significant but small pre-post improvements in GAENE measures. GAENE measures were significantly associated with MATE measures (0.68–0.80). White and male participants had the highest evolution acceptance measures using both the MATE and the GAENE; race had a much stronger contribution to MATE measures as compared to GAENE measures. Race and gender acceptance differences were found to be as large as the differences produced in response to evolution instruction. Conclusions Overall measures of acceptance change will be similar, but not identical, using the MATE and the GAENE. We make several recommendations for the modification or removal of some GAENE items, as well as future research directions for the measurement of evolution acceptance

Innate Immune Responses of Drosophila

<div><p>(A) Posterior region of a third instar larva showing the cuticle and the trachea. These structures provide a physical barrier against infections. Cellular immune reactions consist of phagocytosis, encapsulation, and melanization.</p> <p>(B) A dead and melanized crystal cell phagocytosed by a plasmatocyte.</p> <p>(C) Encapsulation of an egg of a Drosophila parasite. The parasite is a wasp that normally infects larvae. Cells surrounding the egg are lamellocytes. The cells and the egg are stained with a fluorescent nuclear stain.</p> <p>(D) Clot formation occurs during wound healing.</p> <p>(E) Crystal cells in contact with the larval cuticle. The contents of the crystal cells are melanized. Melanization occurs in response to intruding pathogens or parasites and is also observed during wound healing.</p> <p>(F) Humoral immune reaction. The expression of antimicrobial peptides in the larval fat body is induced by microbes. Cells of the fat body appear green due to the presence of a transgene encoding the green fluorescent protein, under the control of the <i>drosomycin</i> promoter. The <i>drosomycin</i> promoter is activated in response to fungal infections and is under the control of the Toll pathway (see <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0020276#pbio-0020276-g002" target="_blank">Figure 2</a>). Antimicrobial peptides are released from the fat body into the hemolymph. This response is therefore systemic. A similar antimicrobial gene activation response can occur locally in specific body parts such as the trachea or the gut (not shown).</p></div

Molecular Components of the Toll and Imd Pathways Involved in Drosophila Immunity

<p>Toll is activated by the processed Spätzle (left). Toll activation leads to intracellular signaling via cytoplasmic proteins Tube and Pelle, leading to the degradation of Cactus and nuclear localization of NF-κB proteins Dorsal and Dif. These transcription factors bind to promoters of target genes, such as <i>drosomycin</i>, activating their transcription. The NF-κB protein for the Imd pathway, Relish, activates <i>diptericin</i> transcription. The signaling events resulting in Dorsal/Dif/Relish activation in the fly are “recycled” in mammals in the activation of mammalian NF-κB. See reviews and <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0020276#pbio-0020276-De1" target="_blank">De Gregorio et al. (2002)</a> for more details.</p

The Long-Term Impacts of Short-Term Professional Development: Science Teachers and Evolution

Background: Although a large body of work in science education has established the pervasive problem of science teachers\u27 alternative conceptions about evolution, knowledge deficits, and anti-evolutionary attitudes, only a handful of interventions have explored the mitigation of these issues using professional development (PD) workshops, and not a single study to our knowledge has investigated if positive outcomes are sustained long after program completion. The central aim of our study was to investigate the long-term consequences of an intensive, short-term professional development program on teachers\u27 knowledge of evolution, acceptance of evolution, and knowledge of the nature of science (NOS). Methods: Program efficacy was examined using a pre-post, delayed post-test design linked to quantitative measures of teacher knowledge, performance (explanatory competence), and acceptance using published instruments shown to generate reliable and valid inferences. Results: Our study is the first to report sustained large effect sizes for both knowledge of evolution, NOS, and acceptance change ~1.5 years after program completion. Concordant with other measures, teacher self-reports indicated that the PD program had lasting effects. Conclusions: Our study suggests that short-term PD built using specific research-based principles can have lasting impacts on teachers\u27 evolutionary knowledge and acceptance. Because evidence of sustained knowledge and belief change is prerequisite to downstream classroom studies (e.g., impacts on student learning), retention of evolutionary knowledge improvements and acceptance change emerge as central, but previously unstudied, components of teacher evolution PD

Testing validity inferences for Genetic Drift Inventory scores using Rasch modeling and item order analyses

Abstract Background Concept inventories (CIs) are commonly used tools for assessing student understanding of scientific and naive ideas, yet the body of empirical evidence supporting the inferences drawn from CI scores is often limited in scope and remains deeply rooted in Classical Test Theory. The Genetic Drift Inventory (GeDI) is a relatively new CI designed for use in diagnosing undergraduate students’ conceptual understanding of genetic drift. This study seeks to expand the sources of evidence examining validity and reliability inferences produced by GeDI scores. Specifically, our research focused on: (1) GeDI instrument and item properties as revealed by Rasch modeling, (2) item order effects on response patterns, and (3) generalization to a new geographic sample. Methods A sample of 336 advanced undergraduate biology majors completed four equivalent versions of the GeDI. Rasch analysis was used to examine instrument dimensionality, item fit properties, person and item reliability, and alignment of item difficulty with person ability. To investigate whether the presentation order of GeDI item suites influenced overall student performance, scores were compared from randomly assigned, equivalent test versions varying in item-suite presentation order. Scores from this sample were also compared with scores from similar but geographically distinct samples to examine generalizability of score patterns. Results Rasch analysis indicated that the GeDI was unidimensional, with good fit to the Rasch model. Items had high reliability and were well matched to the ability of the sample. Person reliability was low. Rotating the GeDI’s item suites had no significant impact on scores, suggesting each suite functioned independently. Scores from our new sample from the NE United States were comparable to those from other geographic regions and provide evidence in support of score generalizability. Overall, most instrument features were robust. Suggestions for improvement include: (1) incorporation of additional items to differentiate high-ability persons and improve person reliability, and (2) re-examination of items with redundant or low difficulty levels. Conclusions Rasch analyses of the GEDI instrument and item order effects expand the range and quality of evidence in support of validity claims and illustrate changes that are likely to improve the quality of this (and other) evolution education instruments