CUMULATIVE TOXICITIES OF NEONICOTINOID INSECTICIDES AND THEIR MIXTURES TO SENSITIVE FRESHWATER INSECTS

Neonicotinoids are neurotoxic insecticides that are commonly applied to combat agricultural pests. Due to widespread application and select physicochemical characteristics, mixtures of different neonicotinoids are frequently detected in freshwater environments. This is of potential concern because these freshwater habitats are populated with ecologically important benthic macroinvertebrates (e.g. Chironomidae), which are markedly sensitive to neonicotinoid compounds. Despite the likelihood of continuous and/or repeated exposure, previous studies have primarily evaluated the individual toxicities of these neurotoxic compounds. Yet, little is known about how mixtures affect sensitive aquatic insects under real world exposure scenarios. Thus, the objectives of this research were to (1) evaluate acute and chronic toxicities of three commonly used neonicotinoids (imidacloprid (IMI), clothianidin (CLO), and thiamethoxam (TMX)) and their mixtures to Chironomidae using Chironomus dilutus as a representative test species, (2) validate single compound and neonicotinoid mixture toxicity predictions to Chironomidae populations under field settings, and (3) identify mechanisms behind species-, life stage-, and compound-specific differences in neonicotinoid toxicity for these sensitive aquatic insects. To address the first objective of this research, acute (96 h, endpoint = lethality) and chronic (28 d, endpoint = cessation of emergence) laboratory-based toxicity tests were carried out, characterizing the toxicities of IMI, CLO, TMX and their binary and ternary mixtures to larval C. dilutus. Using the MIXTOX approach (a statistical technique based on fitting mixture toxicity data to pre-defined mixture models), the nature and magnitude of cumulative toxicity was classified for each neonicotinoid mixture. Several mixtures were found to display cumulative toxicity that significantly deviated from direct, concentration-based additivity. Under acute exposure settings, all IMI-containing mixtures (IMI-CLO, IMI-TMX, and IMI-CLO-TMX) exhibited synergism when the concentrations of IMI in the solution were dominant (up to 7 %, 28 %, and 6 % decreases in survival, respectively), and some mixtures (IMI-CLO and IMI-TMX) displayed antagonism when the other mixture constituent was dominant (up to 19 % and 30 % increases in survival, respectively). Under chronic exposure settings all binary mixtures demonstrated dose-ratio dependent deviation from direct additivity (concentration addition), displaying synergism at high concentrations of CLO (IMI-CLO: 13 % decrease in emergence) or TMX (CLO-TMX and IMI-TMX: 2 % and 4 % decreases in emergence, respectively) and antagonism at high concentrations of IMI (IMI-CLO and IMI-TMX: 5 %, and 2 % increases in emergence, respectively). Under chronic exposures, the ternary mixture (IMI-CLO-TMX) elicited an overall antagonistic effect (2 % increase in emergence). Thus, laboratory-derived bioassays indicated that under both acute and chronic exposure settings, neonicotinoid mixtures had the potential to display cumulative toxicities that deviated from direct additivity. Furthermore, although toxicities of neonicotinoid mixtures were not exactly parallel across different exposure settings, acute tests generally predicted which mixtures were likely to display significant synergism under chronic exposure settings. To determine if laboratory-derived predictions could be used to estimate the toxicities of neonicotinoids and their mixtures under more environmentally realistic exposure settings (Objective 2), chronic (56 day), semi-controlled field studies were carried out in a natural wetland in Saskatchewan’s Prairie Pothole Region. Using in situ limnocorrals fitted with emergence traps, the effects of predicted equitoxic concentrations of IMI, CLO, TMX, and their binary mixtures (concentrations equivalent to 28 d EC50 values; mixtures at 1:1 ratio) were characterized for all emerged aquatic insects (endpoint: abundance) and Chironomidae (endpoint: abundance, biomass, and sex ratios) at the community level. In all treated limnocorrals, there were subtle shifts in insect community composition. Furthermore, at concentrations tested, neonicotinoids and their mixtures significantly impacted Chironomidae abundance and biomass. However, contrary to laboratory predictions, IMI-CLO and IMI-TMX mixtures did not elicit greater-than-additive effects. Furthermore, exposure to IMI, CLO, TMX, and CLO-TMX elicited greater-than-expected declines in Chironomidae abundance and biomass. In addition, CLO significantly shifted sex-ratios of emerged Chironomidae towards female-dominated populations. Thus, although laboratory-derived toxicity estimates could adequately predict relative effects of IMI, CLO, and TMX on Chironomidae populations (e.g. toxicity: IMI ≥ CLO >> TMX), they frequently underestimated the magnitudes of single-compound and neonicotinoid mixture effects under semi-controlled field settings. To better characterize patterns of observed toxicity (e.g. differences among compounds, species, and life-stages), the binding properties of IMI, CLO, and TMX to their molecular target (nicotinic acetylcholine receptors (nAChRs)) were investigated in Chironomidae (Objective 3). Using radioligand binding studies with tritium-labeled IMI ([3H]-IMI) and unlabeled competitors (IMI, CLO, and TMX), nAChR density and neonicotinoid binding affinity were characterized for and compared across two species (C. dilutus and Chironomus riparius) at two different life stages (larval and adult). Despite marked differences in neonicotinoid toxicity, there were no significant species-specific differences in neonicotinoid binding or nAChR density. However, there were life stage-specific differences in nAChR density and binding, and compound-specific differences in binding affinity that reflected previously described patterns in neonicotinoid toxicity (e.g. higher larval sensitivity and relative toxicity of IMI ≥ CLO >> TMX). Furthermore, compared to other insects, Chironomidae displayed relatively high densities of nAChRs with high neonicotinoid affinity, which reflected their sensitivity to these insecticides. Ultimately this work provides a comprehensive characterization of the toxicity of three commonly used neonicotinoid insecticides (IMI, CLO, and TMX) and their mixtures to the sensitive aquatic insect group, Chironomidae. This can help inform regulators and risk assessors focused on assessing risks of neonicotinoids in freshwater environments. Furthermore, by characterizing effects at three levels of biological organization (molecular, individual, and communities), this work provides a basis through which a relative toxicity pathway could be formed, highlighting techniques that could be potentially used to predict large-scale effects for Chironomidae inhabiting neonicotinoid-contaminated aquatic environments. Finally, this work highlights areas worthy of further investigation and provides methodology through which these studies can be carried out, including the characterization of the binding properties and/or expression profiles of nAChRs for other neonicotinoid-sensitive aquatic insects, evaluation of the nAChR binding profiles for other nAChR agonists (e.g. other neonicotinoids, sulfoximines, and butenolides), and further characterization of nAChR binding profiles in Chironomidae (e.g. with α-bungarotoxin or epibatidine) to allow for a more comprehensive, mechanistic understanding of neonicotinoid mixture toxicity

Normative Beliefs and Social Support in Weight Loss Communication

As obesity rates have increased in the past decade, interpersonal communication about weight has taken on greater importance. In this study, we investigate normative beliefs about weight loss communication and the social support provided through such communication. A sample of N = 196 college students reported that they considered weight loss communication to be non-normative in the United States, but that they had positive attitudes toward such communication. In addition, they felt that they would be likely to engage in such conversations themselves. When given the opportunity to respond to a hypothetical weight loss communication scenario, 93% of participants provided a response. Their responses included both action-facilitating and nurturant support, and often blended the two forms of support together. In addition, participants’ responses emphasized health, rather than weight loss alone. Building on results from this study, future health communication campaigns regarding weight loss could aim to a) increase the perception of weight loss communication as normative, b) emphasize health rather than weight loss alone, and c) provide examples of how social support is communicated in this context

The relation between math anxiety and basic numerical and spatial processing

Math anxiety refers to the negative reaction that many people experience when placed in situations that require mathematical problem solving (Richardson & Suinn, 1972). This reaction can range from seemingly minor frustration to overwhelming emotional and physiological disruption (Ashcraft & Moore, 2009). In fact, it has been argued that math anxiety can be considered as a genuine phobia given that it is a state anxiety reaction, shows elevated cognitive and physiological arousal, and is a stimulus-learned fear (Faust, 1992). Math anxiety has been associated with many negative consequences, the most pertinent of which is poor achievement in math. This negative consequence is of central importance in today’s society as people’s mathematical abilities have been shown to strongly influence their employability, productivity, and earnings (Bishop, 1989; Bossiere, Knight, Sabot, 1985; Riviera-Batiz, 1992) A large literature exists demonstrating a negative relation between math anxiety and performance on complex math. That said, there is currently no published research (outside of that presented in this thesis) which investigates whether math anxiety is also related to the basic processes that serve as the foundations for that complex math. In this thesis I examine the relation between math anxiety and three of these basic processes that support complex mathematical problem solving. Specifically, in a series of experiments, I demonstrate that, in addition to their difficulties with complex math, high math anxious adults perform more poorly than their low math anxious peers on measures of counting (Experiments 1 and 2), numerical comparison (Experiment 3 and 4), and spatial processing (Experiment 5 and 6). My findings are then discussed with respect to their implications for our understanding of math anxiety and for potential remediation programs.1 yea

Tracking the Transition from Sublexical to Lexical Processing in Reading Aloud: On the Creation of Orthographic and Phonological Lexical Representations

Participants read aloud a set of nonword letter strings, one at a time that varied in the number of letters. The standard result was observed in two experiments; the time to begin reading aloud increased as letter length increases. This result is standardly understood as reflecting the operation of a serial, left to right translation of graphemes into phonemes. The novel result is that the effect of letter length is statistically eliminated for nonwords that have been repeated a small number of times. This elimination suggests that these nonwords are no longer always being read aloud via a serial left to right sublexical process. Instead, the data are taken as evidence that new orthographic and phonological lexical entries have been created for these nonwords, and that they are now read at least sometimes by recourse to the lexical route. Experiment 2 replicates the interaction between nonword letter length and repetition observed in Experiment 1 and also demonstrates that this interaction is not seen when subjects merely classify the string as appearing in upper or lower case. Implications for existing dual route models of reading aloud and Share’s self-teaching hypothesis are discussed.1 yea

The Relationship Between Social Vulnerability and COVID-19 Incidence Among Louisiana Census Tracts

Objective: To examine the association between the Centers for Disease Control and Prevention (CDC)\u27s Social Vulnerability Index (SVI) and COVID-19 incidence among Louisiana census tracts. Methods: An ecological study comparing the CDC SVI and census tract-level COVID-19 case counts was conducted. Choropleth maps were used to identify census tracts with high levels of both social vulnerability and COVID-19 incidence. Negative binomial regression with random intercepts was used to compare the relationship between overall CDC SVI percentile and its four sub-themes and COVID-19 incidence, adjusting for population density. Results: In a crude stratified analysis, all four CDC SVI sub-themes were significantly associated with COVID-19 incidence. Census tracts with higher levels of social vulnerability were associated with higher COVID-19 incidence after adjusting for population density (adjusted RR: 1.52, 95% CI: 1.41-1.65). Conclusions: The results of this study indicate that increased social vulnerability is linked with COVID-19 incidence. Additional resources should be allocated to areas of increased social disadvantage to reduce the incidence of COVID-19 in vulnerable populations

Alterations in Phospholipid Catabolism in Mycobacterium Tuberculosis LysX Mutant

Mycobacterium tuberculosis lysX mutant, defective for production of lysinylated phosphatidylglycerol, is sensitive to cationic antimicrobial peptides, is not proficient for proliferation in mice lungs, and exhibits altered membrane potential (Maloney et al., 2009). In the present study we show that a lysX complement strain expressing lysX from inducible tet promoter is proficient in restoring lysX phenotypes, confirming that the observed phenotypes are specific to lysX. To evaluate the correlation between changes in membrane potential and lysX activity, we visualized regions of cardiolipin (CL), one of the abundant phospholipids of mycobacteria, by staining with fluorescent dye 10-N-nonyl acridine orange and found that CL is localized as bright spots at septal regions and poles of actively dividing cells, but not in stationary phase cells. lysX mutants were elongated and showed more numerous and brighter CL staining at both mid cell and quarter cell septa, compared with wild type, indicating a defect in the cell division process. Evaluation of 14C-acetic acid incorporation into major phospholipids such as CL, phosphatidylethanolamine (PE), phosphatidylinositol (PI), and their degradation between lysX mutant and its parent revealed differences in the turnover of PE and PI. Our results favor a hypothesis that alterations in phospholipid metabolism could be contributing to changes in membrane potential, hence the observed phenotype of lysX mutant

The Radial Distribution and Excitation of H2 around Young Stars in the HST-ULLYSES Survey

The spatial distribution and evolution of gas in the inner 10 au of protoplanetary disks form the basis for estimating the initial conditions of planet formation. Among the most important constraints derived from spectroscopic observations of the inner disk are the radial distributions of the major gas phase constituents, how the properties of the gas change with inner disk dust evolution, and how chemical abundances and excitation conditions are influenced by the high-energy radiation from the central star. We present a survey of the radial distribution, excitation, and evolution of inner disk molecular hydrogen (H$_{2}$) obtained as part of the $HST$/ULLYSES program. We analyze far-ultraviolet spectroscopy of 71 (63 accreting) pre-main sequence systems in the ULLYSES DR5 release to characterize the H$_{2}$ emission lines, H$_{2}$ dissociation continuum emission, and major photochemical/disk evolution driving UV emissions (Ly$\alpha$, UV continuum, and C IV). We use the widths of the H$_{2}$ emission lines to show that most fluorescent H$_{2}$ arises between 0.1 - 1.4 au from the parent star, and show positive correlations of the average emitting radius with the accretion luminosity and with the dust disk mass. We find a strong correlation between H$_{2}$ dissociation emission and both the accretion-dominated Ly$\alpha$ luminosity and the inner disk dust clearing, painting a picture where water molecules in the inner 3 au are exposed to and dissociated by strong Ly$\alpha$ emission as the opacity of the inner disk declines with time.Comment: 19 pages, 11 figures. Accepted to the Astronomical Journa

Observations of Arp 220 using Herschel-SPIRE: An Unprecedented View of the Molecular Gas in an Extreme Star Formation Environment

We present Herschel SPIRE-FTS observations of Arp~220, a nearby ULIRG. The FTS continuously covers 190 -- 670 microns, providing a good measurement of the continuum and detection of several molecular and atomic species. We detect luminous CO (J = 4-3 to 13-12) and water ladders with comparable total luminosity; very high-J HCN absorption; OH+, H2O+, and HF in absorption; and CI and NII. Modeling of the continuum yields warm dust, with T = 66 K, and an unusually large optical depth of ~5 at 100 microns. Non-LTE modeling of the CO shows two temperature components: cold molecular gas at T ~ 50 K and warm molecular gas at T ~1350 K. The mass of the warm gas is 10% of the cold gas, but dominates the luminosity of the CO ladder. The temperature of the warm gas is in excellent agreement with H2 rotational lines. At 1350 K, H2 dominates the cooling (~20 L_sun/M_sun) in the ISM compared to CO (~0.4 L_sun/M_sun). We found that only a non-ionizing source such as the mechanical energy from supernovae and stellar winds can excite the warm gas and satisfy the energy budget of ~20 L_sun/M_sun. We detect a massive molecular outflow in Arp 220 from the analysis of strong P-Cygni line profiles observed in OH+, H2O+, and H2O. The outflow has a mass > 10^{7} M_sun and is bound to the nuclei with velocity < 250 km/s. The large column densities observed for these molecular ions strongly favor the existence of an X-ray luminous AGN (10^{44} ergs/s) in Arp 220.Comment: Accepted in ApJ on September 1, 201

Unsubstantiated Conclusions: A Scoping Review on Generational Differences of Leadership in Academic Libraries

The academic library profession is experiencing a large turnover in leadership. To date, information on differences in the generational expectations about how to lead is scarce and the research is contradictory. This article presents a scoping review of the literature on generational expectations of academic library leaders. Based on predefined eligibility criteria, the authors searched twelve bibliographic databases and performed a broad web search. 5,435 articles were located and considered for inclusion, however, only four eligible articles were identified and included for analysis. There is little empirical evidence that generational differences are evident in the academic library setting or in individual leadership expectations. There is a lack of original research on generational differences in leadership in libraries, however, anecdotal and opinion literature is drawing attention to this topic in ways that cannot be validated

The Two-Domain LysX Protein of Mycobacterium tuberculosis Is Required for Production of Lysinylated Phosphatidylglycerol and Resistance to Cationic Antimicrobial Peptides

The well-recognized phospholipids (PLs) of Mycobacterium tuberculosis (Mtb) include several acidic species such as phosphatidylglycerol (PG), cardiolipin, phosphatidylinositol and its mannoside derivatives, in addition to a single basic species, phosphatidylethanolamine. Here we demonstrate that an additional basic PL, lysinylated PG (L-PG), is a component of the PLs of Mtb H37Rv and that the lysX gene encoding the two-domain lysyl-transferase (mprF)-lysyl-tRNA synthetase (lysU) protein is responsible for L-PG production. The Mtb lysX mutant is sensitive to cationic antibiotics and peptides, shows increased association with lysosome-associated membrane protein–positive vesicles, and it exhibits altered membrane potential compared to wild type. A lysX complementing strain expressing the intact lysX gene, but not one expressing mprF alone, restored the production of L-PG and rescued the lysX mutant phenotypes, indicating that the expression of both proteins is required for LysX function. The lysX mutant also showed defective growth in mouse and guinea pig lungs and showed reduced pathology relative to wild type, indicating that LysX activity is required for full virulence. Together, our results suggest that LysX-mediated production of L-PG is necessary for the maintenance of optimal membrane integrity and for survival of the pathogen upon infection