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Plastic pollution is widely recognised as a threat to life in our oceans and current trends indicate that the marine plastic burden and its ecological impact will continue to escalate. However, investigations of plastic pollution on marine microbial communities largely focus on microbes that attach to plastics, whereas impacts of plastic debris-leached chemicals remain poorly understood. We set out to investigate the impact of plastic leachate on natural communities of marine microbes using microcosm experiments, monitoring impacts on both the structure and function of this community. Our results show that exposure to leachate from polyvinyl chloride (PVC) matting negatively impact a broad group of photosynthetic microbes, both bacterial and eukaryotic, causing sharp declines in cell abundance, photosynthetic efficiency, and total chlorophyll. Further, PVC leachate impacted both taxonomic and functional diversity of the entire microbial community, with dramatic decreases in the abundance of key marine taxa including Synechococcus, SAR11 and members of the Rhodobacterales. Functional gene and metagenome-derived genome analyses showed that, while some key groups decline, fast-adapting, motile organisms were enriched, as were genes usually associated with pathogenicity and an increased capacity to metabolise organic compounds leached from PVC. These results reveal that PVC leachates have the potential to impact key organisms at the base of the marine food web, which could have significant flow-on effects for entire marine ecosystems. We are now investigating how specific components of the plastic leachate contribute to its toxicity to photosynthetic marine microbes. Also see: https://micro2022.sciencesconf.org/425929/document, In MICRO 2022, Online Atlas Edition: Plastic Pollution from MACRO to nano

Additional file 1: Figure S1. Microcosm experimental design. PVC plastic leachate was prepared by cutting PVC matting into small pieces, leaching them in Turks Island Salt solution for 5 days, and 0.2 μm filtering to remove plastic pieces and microorganisms from the PVC leachate solution. Experimental bottles containing seawater were set up by adding the PVC leachate in two different concentrations for 1% PVC leachate and 10% PVC leachate treatments, adding ZnCl2 in two concentrations for ZnL (0.13 mg L-1) and ZnH (1.3 mg L-1) treatments, and having one no addition seawater control. Quadruplicate replicate bottles were set up for each treatment and the control and incubated in an outside tank with light and temperature to mimic the conditions of the seawater source (issues with two ZnH treatment bottles meant they were not able to be included in the final analysis). Figure S2. Gating strategies used to quantify photosynthetic communities via flow cytometry analysis. A representative sample of a natural population (panel 1) illustrates how Chlorophyll and phycoerythrin (PE) autofluorescence were used to discriminate two groups of pigment-containing organisms: photosynthetic eukaryotes and Synechococcus. Specifically, eukaryotes were distinguished from Synechococcus based on their high Chlorophyll autofluorescence and relatively low PE fluorescence (panel 2). From there different eukaryotic communities were then discriminated based on FSC and PE content (panel 3). Synechococcus communities were discriminated based on PE and SSC content (panel 4). The gating strategy outlined was used for all of the samples. Figure S3. Gating strategies used to quantify heterotrophic bacterial and viral communities via flow cytometric analysis. A representative sample of a natural population (panel 1) illustrates how Sybr Green I fluorescence intensity and violet SSC were used to discriminate viral and bacterial communities. Contour plots of these two communities enabled identification of 2 different populations of bacteria, low DNA-containing bacteria (LDNAb) and high DNA-containing bacteria (HDNAb) (panel 2), and 5 distinct viral populations (panel 3). The gating strategy outlined was used for all the samples. Figure S4. Impact of PVC plastic leachate and zinc treatments on various flow cytometric populations. Changes in (a) photosynthetic Nano-eukaryote (NEUK) and phycoerythrin-rich eukaryote (PeEUK) population abundances and in (b) the ratio of Synechococcus to total eukaryotic primary producers community abundances are shown during the 6-day experiment. The effect of the different treatments on (c) the ratios between HDNAb vs LDNAb bacterial communities (HL_ratio) and total viral to total bacterial communities (VB_ratio), and their impact on (d) the five different viral populations are presented over the 6-day experiment. Data points are derived from the daily mean flow-cytometrically derived abundance (cells ml-1) of quadruplicate, biologically-independent samples (except ZnH for which just 2 replicates are available) for each day of the 6-day experiment. Error bars on each point represent the standard deviation. The lower-case letters (a-c) on panels a, b and c indicate which treatments were found to be statistically different (p < 0.01) from each other at the final time point (Additional file 2: Table S5). Significance was calculated with an ANOVA test followed by pairwise t-test and p-value false discovery rate (FDR) corrected. Figure S5. Composition of the bacterial and eukaryotic communities before (T0) and after exposure (day six) to PVC leachate and zinc. Boxplots indicate the average Shannon diversity for the (a) bacterial and (b) eukaryotic communities for each of the treatments. Different lower-case letters within the panels indicate a significance difference (p < 0.01, FDR corrected, Additional file 2: Table S7) from the control in the Shannon diversity. Non-metric multidimensional scaling (nMDS) plots are based on a Bray-Curtis dissimilarity matrix of the rarefied (c) bacterial and (d) eukaryotic community composition for each treatment bottle with axes indicating the percentage of explanation for the first two components. Stacked bar plots show the shift of (e) bacterial classes that contribute to > 1% of the total relative abundance per samples and the shift of (f) eukaryotic phyla that contribute to > 1% of the total relative abundance across treatments. The communities experienced changes in the relative abundance of some bacterial groups during the course of the experiment (from T0 to SW on day six in Fig. S5), likely due to bottle effects; however, these changes were less pronounced than the treatment effects. Figure S6. Bacterial community composition across the different treatments. Stacked bar plots show the bacterial Amplicon Sequence Variants (ASVs) that contribute to > 1% of the total relative abundance for seawater replicates at T0 and each treatment sample replicate at day 6. Figure S7. Eukaryotic community composition across the different treatments. Stacked bar plots show the eukaryotic Amplicon Sequence Variants (ASVs) that contribute to > 1% of the total relative abundance for seawater replicates at T0 and each treatment sample replicate at day 6. Figure S8. Average doubling times (h) for the isolated bacterial MAGs aggregated at the family level. Doubling times were calculated based on codon frequencies of multiple, highly expressed ribosomal genes for each MAG following the R package gRodon.

Bathyplectes anurus (Thomson) and B. curculionis (Thomson) (Hymenoptera: Ichneumonidae) are specialist parasitoids introduced to the United States for classical biological control of alfalfa weevil, Hypera postica (Coleoptera: Curculionidae). Adults of both species are morphologically similar, generally described as wasps ≈3-4 mm long with black, robust bodies. The Bathyplectes spp. occupy sympatric ranges throughout much of the United States and often coexist within alfalfa fields. In Virginia, B. anurus is the primary biological control agent, accounting for more than 90% of alfalfa weevil parasitization. A previous study, however, found that the levels of control by B. anurus varied among the three alfalfa-growing regions of Virginia, and noted that little is known about the mechanisms or factors responsible for the differential levels of parasitization. Of the factors that may affect host parasitization, three were addressed in this study: population density and spatial distribution of host and parasitoid, the effectiveness of parasitoids in response to host density as measured by the population functional response, and genetic variation among and between populations of parasitoids. GPS-referenced quadrat sampling was conducted in alfalfa fields in the Piedmont and southwestern region to assess alfalfa weevil population levels and spatial distribution, and the level and distribution of parasitization by B. anurus and B. curculionis. Results showed that there was no significant difference in alfalfa weevil densities among alfalfa fields in the Piedmont and southwestern region, and also no significant difference between regions in the level of parasitization. Mean alfalfa weevil density per 0.2-m2 quadrat per sampling date was 11.0 in the Piedmont and 8.0 in the southwestern region; mean percent parasitization per 0.2-m2 quadrat per sampling date was 9.1% in the Piedmont and 9.9% in the southwestern region. The spatial distributions of alfalfa weevil larvae and parasitization were found to be aggregated in all alfalfa fields sampled. The population functional response of B. anurus attack on alfalfa weevil was determined qualitatively to be Type II in all alfalfa fields sampled, except the field located at Blacksburg in the southwestern region. The Type II functional response suggests that, in general, the parasitoid has an inverse density dependent attack response to the density of alfalfa weevil larvae in the two regions of Virginia. Molecular analyses were conducted to 1) derive genetic sequences for B. anurus and B. curculionis, which could be used to identify and differentiate the two species, and 2) test for genetic variation within and between regional populations of Bathyplectes. Sequences for each species were obtained for the D2–D3 region of the 28S ribosomal DNA (28S rDNA) gene; sequence identity between B. anurus and B. curculionis was 96.6%. The 28S rDNA sequences were also obtained for another Bathyplectes species, possibly B. stenostigma, and for four taxa of Hymenoptera that hyperparasitize B. anurus and B. curculionis cocoons. Sequences were obtained for B. anurus and B. curculionis for a portion of the mitochondrial gene cytochrome oxidase subunit 1 (COI); sequence identity between B. anurus and B. curculionis was 89.7%. Genetic variation in the COI gene was observed for both species. One variation of the COI sequence expressed by 25% of B. anurus specimens (Haplotype 2) might indicate regional genetic variation correlated to temperature, in particular the average number of days per year that a region experiences temperatures above 32°C. Two major COI sequence haplotypes found in B. curculionis specimens might be indicative of incipient speciation. Ph. D.

This qualitative program evaluation examines the career decision-making processes and career choices of nine, African American women who participated in the Cooperating Hampton Roads Organization for Minorities in Engineering (CHROME) and who graduated from urban, rural or suburban high schools in the year 2000. The CHROME program is a nonprofit, pre-college intervention program that encourages underrepresented minority and female students to enter science, technically related, engineering, and math (STEM) career fields. The study describes career choices and decisions made by each participant over a five-year period since high school graduation. Data was collected through an Annual Report, Post High School Questionnaires, Environmental Support Questionnaires, Career Choice Questionnaires, Senior Reports, and standardized open-ended interviews. Data was analyzed using a model based on Helen C. Farmer's Conceptual Models, John Ogbu's Caste Theory and Feminist Theory. The CHROME program, based on its stated goals and tenets, was also analyzed against study findings. Findings indicated that participants received very low levels of support from counselors and teachers to pursue STEM careers and high levels of support from parents and family, the CHROME program and financial backing. Findings of this study also indicated that the majority of CHROME alumna persisted in STEM careers. The most successful participants, in terms of undergraduate degree completion and occupational prestige, were the African American women who remained single, experienced no critical incidents, came from a middle class to upper middle class socioeconomic background, and did not have children.

Refereed/Peer-reviewed Adolescence is a critical period of social and neural development. Brain regions which process social information develop throughout adolescence as young people learn to navigate social environments. Studies investigating brain structural connectivity (indexed by white matter (WM) integrity), and social connectedness in adolescents have been limited until recently, with literature stemming mostly from adult samples, broad age ranges within adolescence or based on social network characteristics as opposed to social connectedness. This cross-sectional study of 12-year-olds (N = 73) explored the relationship between social connectedness (SCS) and structural connectivity in early adolescence, to gauge how this snapshot of WM development is associated with social behaviour. Whole brain voxel-wise diffusion tensor imaging was undertaken to determine correlations between SCS and fractional anisotropy (FA), radial (RD) and axial (AD) diffusivity of clusters within WM tracts. Significant negative relationships between FA and SCS scores were found in clusters within 11 WM tracts, with significant positive correlations between SCS and both RD and AD across clusters within 13 and 8 clusters, respectively. Clusters within the genu of the corpus callosum (CCgn) showed strong correlations for all three metrics, and regression models that included gender, age, and psychological distress, revealed SCS to be the only significant predictor of CCgn FA, RD and AD values. Overall, these findings suggest that those with lower social connectedness had a WM profile suggestive of reduced axonal density and/or coherence. Longitudinal research is needed to track such WM profiles during adolescent development and determine the associations with mental health and well-being outcomes.