A Toxicologist's Perspective on Having and Doing it All: Teaching, Research, and Service at a Small Liberal Arts College

In the United States, a small liberal arts college is loosely defined as an institution that provides a residential and comprehensive education to students seeking a bachelor’s degree. There are many challenges and opportunities that exist within this educational framework for faculty who engage as teacher-scholars. A primary challenge is making time for research, teaching, and service. However, this can become an opportunity when undergraduate research experiences are integrated into the curriculum. This approach benefits students, who report a gain in confidence, experience, and increased enrollment in advanced degrees. Developing collaborations with faculty at other colleges, especially R1 research institutions, can be extremely helpful in supporting and advancing ones research year-round. Furthermore, salary is often only required for three months, making a liberal arts faculty member less expensive (and more qualified) than a postdoc. A second challenge is how to balance and understand the expectations set forth for tenure and promotion. Productivity in the lab can be advanced during the school year through student independent studies or thesis work; this can serve both the student and the faculty. Scholarship in teaching and learning is very important to many liberal arts schools, thus time spent working on and publishing about these subjects may be an adequate alternative to a “traditional” research trajectory. Finally, toxicology’s interface of many scientific disciplines positions professionals in the field in a strong position to succeed as teacher-scholars in small liberal arts colleges

Signatures of selection in natural populations adapted to chronic pollution

<p>Abstract</p> <p>Background</p> <p>Populations of the teleost fish <it>Fundulus heteroclitus </it>appear to flourish in heavily polluted and geographically separated Superfund sites. Populations from three Superfund sites (New Bedford Harbor, MA, Newark Bay, NJ, and Elizabeth River, VA) have independently evolved adaptive resistance to chemical pollutants. In these polluted populations, natural selection likely has altered allele frequencies of loci that affect fitness or that are linked to these loci. The aim of this study was to identify loci that exhibit non-neutral behavior in the <it>F. heteroclitus </it>genome in polluted populations <it>versus </it>clean reference populations.</p> <p>Results</p> <p>To detect signatures of natural selection and thus identify genetic bases for adaptation to anthropogenic stressors, we examined allele frequencies for many hundreds of amplified fragment length polymorphism markers among populations of <it>F. heteroclitus</it>. Specifically, we contrasted populations from three Superfund sites (New Bedford Harbor, MA, Newark Bay, NJ, and Elizabeth River, VA) to clean reference populations flanking the polluted sites. When empirical F_STvalues were compared to a simulated distribution of F_STvalues, 24 distinct outlier loci were identified among pairwise comparisons of pollutant impacted <it>F. heteroclitus </it>populations and both surrounding reference populations. Upon removal of all outlier loci, there was a strong correlation (R²= 0.79, p < 0.0001) between genetic and geographical distance. This apparently neutral evolutionary pattern was not evident when outlier loci were included (R²= 0.092, p = 0.0721). Two outlier loci were shared between New Bedford Harbor and Elizabeth River populations, and two different loci were shared between Newark Bay and Elizabeth River populations.</p> <p>Conclusion</p> <p>In total, 1% to 6% of loci are implicated as being under selection or linked to areas of the genome under selection in three <it>F. heteroclitus </it>populations that reside in polluted estuaries. Shared loci among polluted sites indicate that selection may be acting on multiple loci involved in adaptation, and loci shared between polluted sites potentially are involved in a generalized adaptive response.</p

The Schistosoma mansoni Cytochrome P450 (CYP3050A1) Is Essential for Worm Survival and Egg Development.

Schistosomiasis affects millions of people in developing countries and is responsible for more than 200,000 deaths annually. Because of toxicity and limited spectrum of activity of alternatives, there is effectively only one drug, praziquantel, available for its treatment. Recent data suggest that drug resistance could soon be a problem. There is therefore the need to identify new drug targets and develop drugs for the treatment of schistosomiasis. Analysis of the Schistosoma mansoni genome sequence for proteins involved in detoxification processes found that it encodes a single cytochrome P450 (CYP450) gene. Here we report that the 1452 bp open reading frame has a characteristic heme-binding region in its catalytic domain with a conserved heme ligating cysteine, a hydrophobic leader sequence present as the membrane interacting region, and overall structural conservation. The highest sequence identity to human CYP450s is 22%. Double stranded RNA (dsRNA) silencing of S. mansoni (Sm)CYP450 in schistosomula results in worm death. Treating larval or adult worms with antifungal azole CYP450 inhibitors results in worm death at low micromolar concentrations. In addition, combinations of SmCYP450-specific dsRNA and miconazole show additive schistosomicidal effects supporting the hypothesis that SmCYP450 is the target of miconazole. Treatment of developing S. mansoni eggs with miconazole results in a dose dependent arrest in embryonic development. Our results indicate that SmCYP450 is essential for worm survival and egg development and validates it as a novel drug target. Preliminary structure-activity relationship suggests that the 1-(2,4-dichlorophenyl)-2-(1H-imidazol-1-yl)ethan-1-ol moiety of miconazole is necessary for activity and that miconazole activity and selectivity could be improved by rational drug design

Functional genomics of physiological plasticity and local adaptation in killifish

Evolutionary solutions to the physiological challenges of life in highly variable habitats can span the continuum from evolution of a cosmopolitan plastic phenotype to the evolution of locally adapted phenotypes. Killifish (Fundulus sp.) have evolved both highly plastic and locally adapted phenotypes within different selective contexts, providing a comparative system in which to explore the genomic underpinnings of physiological plasticity and adaptive variation. Importantly, extensive variation exists among populations and species for tolerance to a variety of stressors, and we exploit this variation in comparative studies to yield insights into the genomic basis of evolved phenotypic variation. Notably, species of Fundulus occupy the continuum of osmotic habitats from freshwater to marine and populations within Fundulus heteroclitus span far greater variation in pollution tolerance than across all species of fish. Here, we explore how transcriptome regulation underpins extreme physiological plasticity on osmotic shock and how genomic and transcriptomic variation is associated with locally evolved pollution tolerance. We show that F. heteroclitus quickly acclimate to extreme osmotic shock by mounting a dramatic rapid transcriptomic response including an early crisis control phase followed by a tissue remodeling phase involving many regulatory pathways. We also show that convergent evolution of locally adapted pollution tolerance involves complex patterns of gene expression and genome sequence variation, which is confounded with body-weight dependence for some genes. Similarly, exploiting the natural phenotypic variation associated with other established and emerging model organisms is likely to greatly accelerate the pace of discovery of the genomic basis of phenotypic variation. The American Genetic Association. 2010. All rights reserved. For permissions, please email: [email protected] © The American Genetic Association. 2010. All rights reserved. For permissions, please email: [email protected]

Can diversifying selection be distinguished from history in geographic clines? A population genomic study of killifish (Fundulus heteroclitus)

© The Author(s), 2012. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in PLoS ONE 7 (2012): e45138, doi:10.1371/journal.pone.0045138.A common geographical pattern of genetic variation is the one-dimensional cline. Clines may be maintained by diversifying selection across a geographical gradient but can also reflect historical processes such as allopatry followed by secondary contact. To identify loci that may be undergoing diversifying selection, we examined the distribution of geographical variation patterns across the range of the killifish (Fundulus heteroclitus) in 310 loci, including microsatellites, allozymes, and single nucleotide polymorphisms. We employed two approaches to detect loci under strong diversifying selection. First, we developed an automated method to identify clinal variation on a per-locus basis and examined the distribution of clines to detect those that exhibited signifcantly steeper slopes. Second, we employed a classic -outlier method as a complementary approach. We also assessed performance of these techniques using simulations. Overall, latitudinal clines were detected in nearly half of all loci genotyped (i.e., all eight microsatellite loci, 12 of 16 allozyme loci and 44% of the 285 SNPs). With the exception of few outlier loci (notably mtDNA and malate dehydrogenase), the positions and slopes of Fundulus clines were statistically indistinguishable. The high frequency of latitudinal clines across the genome indicates that secondary contact plays a central role in the historical demography of this species. Our simulation results indicate that accurately detecting diversifying selection using genome scans is extremely difficult in species with a strong signal of secondary contact; neutral evolution under this history produces clines as steep as those expected under selection. Based on these results, we propose that demographic history can explain all clinal patterns observed in F. heteroclitus without invoking natural selection to either establish or maintain the pattern we observe today.This work was supported by the National Science Foundation (DEB-0919064 and IOS-105226

SNP identification, verification, and utility for population genetics in a non-model genus

<p>Abstract</p> <p>Background</p> <p>By targeting SNPs contained in both coding and non-coding areas of the genome, we are able to identify genetic differences and characterize genome-wide patterns of variation among individuals, populations and species. We investigated the utility of 454 sequencing and MassARRAY genotyping for population genetics in natural populations of the teleost, <it>Fundulus heteroclitus </it>as well as closely related <it>Fundulus </it>species (<it>F. grandis</it>, <it>F. majalis </it>and <it>F. similis</it>).</p> <p>Results</p> <p>We used 454 pyrosequencing and MassARRAY genotyping technology to identify and type 458 genome-wide SNPs and determine genetic differentiation within and between populations and species of <it>Fundulus</it>. Specifically, pyrosequencing identified 96 putative SNPs across coding and non-coding regions of the <it>F. heteroclitus </it>genome: 88.8% were verified as true SNPs with MassARRAY. Additionally, putative SNPs identified in <it>F. heteroclitus </it>EST sequences were verified in most (86.5%) <it>F. heteroclitus </it>individuals; fewer were genotyped in <it>F. grandis </it>(74.4%), <it>F. majalis </it>(72.9%), and <it>F. similis </it>(60.7%) individuals. SNPs were polymorphic and showed latitudinal clinal variation separating northern and southern populations and established isolation by distance in <it>F. heteroclitus </it>populations. In <it>F. grandis</it>, SNPs were less polymorphic but still established isolation by distance. Markers differentiated species and populations.</p> <p>Conclusions</p> <p>In total, these approaches were used to quickly determine differences within the <it>Fundulus </it>genome and provide markers for population genetic studies.</p

Impact of perceived interpersonal similarity on attention to the eyes of same‑race and other‑race faces

This research was supported by the Social Sciences and Humanities Research Council of Canada (435-2013-0992) and Canada Foundation for Innovation (9297) Grants to Kerry Kawakami.One reason for the persistence of racial discrimination may be anticipated dissimilarity with racial outgroup members that prevent meaningful interactions. In the present research, we investigated whether perceived similarity would impact the processing of same-race and other-race faces.Specifically, in two experiments, we varied the extent to which White participants were ostensibly similar to targets via bogus feedback on a personality test. With an eye tracker, we measured the effect of this manipulation on attention to the eyes, a critical region for person perception and face memory. In Experiment 1, we monitored the impact of perceived interpersonal similarity on White participants’ attention to the eyes of same-race White targets. In Experiment 2, we replicated this procedure, but White participants were presented with either same-race White targets or other-race Black targets in a between-subjects design. The pattern of results in both experiments indicated a positive linear effect of similarity—greater perceived similarity between participants and targets predicted more attention to the eyes of White and Black faces. The implications of these findings related to top-down effects of perceived similarity for our understanding of basic processes in face perception, as well as intergroup relations, are discussed.Social Sciences and Humanities Research Council of Canada (SSHRC) 435-2013-0992Canada Foundation for Innovation CGIAR 929

The role of Nrf1 and Nrf2 in the regulation of glutathione and redox dynamics in the developing zebrafish embryo

© The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Redox Biology 13 (2017): 207–218, doi:10.1016/j.redox.2017.05.023.Redox signaling is important for embryogenesis, guiding pathways that govern processes crucial for embryo patterning, including cell polarization, proliferation, and apoptosis. Exposure to pro-oxidants during this period can be deleterious, resulting in altered physiology, teratogenesis, later-life diseases, or lethality. We previously reported that the glutathione antioxidant defense system becomes increasingly robust, including a doubling of total glutathione and dynamic shifts in the glutathione redox potential at specific stages during embryonic development in the zebrafish, Danio rerio. However, the mechanisms underlying these changes are unclear, as is the effectiveness of the glutathione system in ameliorating oxidative insults to the embryo at different stages. Here, we examine how the glutathione system responds to the model pro-oxidants tert-butylhydroperoxide and tert-butylhydroquinone at different developmental stages, and the role of Nuclear factor erythroid 2-related factor (Nrf) proteins in regulating developmental glutathione redox status. Embryos became increasingly sensitive to pro-oxidants after 72 h post-fertilization (hpf), after which the duration of the recovery period for the glutathione redox potential was increased. To determine whether the doubling of glutathione or the dynamic changes in glutathione redox potential are mediated by zebrafish paralogs of Nrf transcription factors, morpholino oligonucleotides were used to knock down translation of Nrf1 and Nrf2 (nrf1a, nrf1b, nrf2a, nrf2b). Knockdown of Nrf1a or Nrf1b perturbed glutathione redox state until 72 hpf. Knockdown of Nrf2 paralogs also perturbed glutathione redox state but did not significantly affect the response of glutathione to pro-oxidants. Nrf1b morphants had decreased gene expression of glutathione synthesis enzymes, while hsp70 increased in Nrf2b morphants. This work demonstrates that despite having a more robust glutathione system, embryos become more sensitive to oxidative stress later in development, and that neither Nrf1 nor Nrf2 alone appear to be essential for the response and recovery of glutathione to oxidative insults.This research was supported by several NIH grants, including F32ES028085 (to KES), F32ES017585 (to ART-L), F32ES019832 (to LMW), P20GM103423 (to LMW), R01ES025748 (to ART-L), R01ES015912 (JJS), and R01ES016366 (MEH). Additional research support was provided by the J. Seward Johnson Fund at WHOI and the WHOI Postdoctoral Scholar Award with funding from Walter A. and Hope Noyes Smith (to ART-L)

Determining the Phosphorus Release Curve for Smizyme TS G5 2,500 Phytase from 500 to 2,500 FTU/kg in Nursery Pig Diets

A total of 320 pigs (DNA 241 × 600; initially 26.2 ± 0.48 lb BW) were used in a 21-d growth study to determine the available P (aP) release curve for Smizyme TS G5 2,500 (Barentz, Woodbury, MN). At approximately 19 d of age, pigs were weaned, randomly allotted to pens, and fed common starter diets. Pigs were blocked by average pen body weight (BW) and randomly allotted to 1 of 8 dietary treatments on d 18 post-weaning, considered d 0 of the study. Dietary treatments were derived from a single basal diet and ingredients including phytase, monocalcium P, limestone, and sand were added to create the treatment diets. Treatments included 3 diets containing increasing (0.11, 0.19, and 0.27%) inorganic P from monocalcium P, or 5 diets with increasing phytase (500, 1,000, 1,500, 2,000, or 2,500 FTU/kg) added to the diet containing 0.11% aP. All diets were corn-soybean meal-canola meal-based and were formulated to contain 1.24% SID Lys and an analyzed Ca:P ratio of 1.10:1. Prior to the beginning of the study, all pigs were fed a diet containing 0.11% aP for a 2-d period (d 16 to 18 post-weaning). At the conclusion of the study, 1 pig, closest to the mean weight of each pen, was euthanized and the right fibula, rib, and metacarpal were collected to determine bone ash, density, and total bone P. For the overall experimental period, pigs fed increasing inorganic P had improved (quadratic, P ≤ 0.053) ADG, ADFI, F/G, and final BW. Pigs fed increasing phytase had improved (quadratic, P ≤ 0.004) ADG, F/G, and final BW and increased (linear, P = 0.019) ADFI. For fibula, rib, and metacarpal characteristics, pigs fed increasing levels of aP from inorganic P had increased (linear, P \u3c 0.001) bone ash weight, bone ash percentage, bone density, and bone P. Additionally, pigs fed increasing phytase had increased (P \u3c 0.05) bone ash weight, bone ash percentage, bone density, and bone P in either a linear or quadratic manner depending upon bone. The available P release curve generated for Smizyme TS G5 2,500 for percentage bone ash is: aP = (0.219 × FTU) ÷ (993.238 + FTU)