Wk Of Exposure Research Articles

Age matters: Comparing life-stage responses to diluted bitumen exposure in coho salmon (Oncorhynchus kisutch)

Millions of liters of diluted bitumen (dilbit), a crude oil product from Canada's oil sands region, is transported through critical Pacific salmon habitat each day. While the toxicity of the water-soluble fraction of dilbit (WSFd) to early life-stages of salmon is known, quantitative data on life-stage differences in sensitivity to WSFd is missing. To fill this knowledge gap, we exposed two juvenile life-stages of coho salmon (O. kisutch) in parallel to very low (parts per billion), environmentally-relevant concentrations of WSFd for acute (48 h) and sub-chronic (4 wk) durations. The relative sensitivities of the two life-stages (fry and parr) were assessed by comparing the timing and magnitude of biological responses using common organismal and molecular endpoints of crude oil exposure. A significant reduction in body condition occurred in both fry and parr after 4 wk exposure to WSFd. Both life-stages also experienced a concentration-dependent decrease in time-to-loss-of-equilibrium during a hypoxia challenge test at both 48 h and 4 wk of exposure. Although organismal responses were similar, molecular responses were distinct between life-stages. In general, unexposed fry had higher baseline values of hepatic phase I biotransformation indicators than unexposed parr, but induction of EROD activity and cyp1a mRNA expression in response to WSFd exposure was greater in parr than in fry. Neither gst nor hsp70 mRNA expression, markers of phase II biotransformation and cell stress, respectively, were reliably altered by WSFd exposure in either life-stage. Taken together, results of this study do not support differential sensitivities of coho fry and parr to WSFd. All the same, the potential for ontogenic differences in the expression and induction of phase I biotransformation need to be considered because age does matter for these endpoints if they are used as bioindicators of exposure in post-spill impact assessments.

Muc5b plays a role in the development of inflammation and fibrosis in hypersensitivity pneumonitis induced by Saccharopolyspora rectivirgula.

Previously we have shown that a gain-of-function MUC5B promoter variant (rs35705950) is the strongest risk factor for the development of idiopathic pulmonary fibrosis. We have also found that Muc5b overexpression reduces mucociliary clearance in mice, potentially leading to recurrent injury to the bronchoalveolar epithelia. Hypersensitivity pneumonitis (HP) is induced by inhalation of numerous causative antigens that may be affected by mucociliary clearance. We conducted this study to determine the role of Muc5b in a mouse model of HP induced by Saccharopolyspora rectivirgula (SR) antigen. We used Muc5b-deficient and wild-type (WT) mice to determine whether Muc5b plays a role in inflammation and fibrosis at 3 and 6 wk in an SR model of HP. We measured cell concentrations and MUC5B expression in whole lung lavage (WLL) and quantified fibrosis using hydroxyproline assay and second harmonic generation. Muc5b expression in WLL fluid was significantly increased in SR-exposed WT mice compared with saline controls. WT mice challenged with SR developed more inflammation and lung fibrosis at 6 wk compared with 3 wk postexposure. Moreover, we found that 6 wk following challenge with SR, Muc5b-deficient mice had less lung inflammation and less lung fibrosis than Muc5b WT mice. Furthermore, Muc5b-deficient mice had significantly lower concentrations of TGF-β1 in the WLL compared with Muc5b WT mice at 6 wk of exposure. Muc5b appears to play a role in fibrosis in the animal model of HP and this may have implications for HP in humans.

Fundamentals of vaping-associated pulmonary injury leading to severe respiratory distress.

Vaping of flavored liquids has been touted as safe alternative to traditional cigarette smoking with decreased health risks. The popularity of vaping has dramatically increased over the last decade, particularly among teenagers who incorporate vaping into their daily life as a social activity. Despite widespread and increasing adoption of vaping among young adults, there is little information on long-term consequences of vaping and potential health risks. This study demonstrates vaping-induced pulmonary injury using commercial JUUL pens with flavored vape juice using an inhalation exposure murine model. Profound pathological changes to upper airway, lung tissue architecture, and cellular structure are evident within 9 wk of exposure. Marked histologic changes include increased parenchyma tissue density, cellular infiltrates proximal to airway passages, alveolar rarefaction, increased collagen deposition, and bronchial thickening with elastin fiber disruption. Transcriptional reprogramming includes significant changes to gene families coding for xenobiotic response, glycerolipid metabolic processes, and oxidative stress. Cardiac systemic output is moderately but significantly impaired with pulmonary side ventricular chamber enlargement. This vaping-induced pulmonary injury model demonstrates mechanistic underpinnings of vaping-related pathologic injury.

Variation in southern chinch bug (Blissus insularis) survival and damage on St. Augustinegrass germplasm

AbstractSt. Augustinegrass [Stenotaphrum secundatum (Walter) Kuntze] cultivars tend to be susceptible to the southern chinch bug (Blissus insularis; SCB). This insect feeds on the plant by sucking the sap, causing leaf chlorosis and necrosis, and can kill whole lawns. Resistant cultivars can simplify SCB management and reduce insecticide use. However, little research has been conducted to identify resistant germplasm that can be used in breeding. The objectives of this study were to (i) evaluate the level of damage caused by SCB feeding on sixteen St. Augustinegrass genotypes, and (ii) determine the attractiveness and quality of those genotypes to SCB in choice and no‐choice scenarios under greenhouse conditions. After a period of 6 wk of exposure in a choice study, SCB feeding damage on St. Augustinegrass [S. secundatum (Walter) Kuntze] cultivars ‘FX‐10’, ‘DALSA 0605’ (TamStar®), ‘SS‐100’ (Palmetto®), and pembagrass [Stenotaphrum dimidiatum (L.) Brongn.] accession PI 289729 ranged from 3 to 21%, demonstrating the highest resistance to SCB. Breeding lines XSA 10403, XSA 11168, and XSA 12354 suffered significant damage (>68%), indicating a high susceptibility to SCB. In a no‐choice study, ‘615866’ (Seville®), ‘SS‐100’ and most breeding lines exhibited intermediate levels of SCB susceptibility, with SCB survival ranging from 35 to 74%. FX‐10, ‘DALSA 0605’, and PI 289729 were not suitable for SCB feeding and oviposition and exhibited two‐ to five‐fold reductions in the number of live SCB and eggs recovered per plant compared to most breeding lines. Several breeding lines proved to have higher levels of tolerance than cultivar ‘Raleigh’. The magnitude of the differences between the most resistant and susceptible lines indicates that it is possible to generate biparental populations with enough segregation to conduct QTL mapping for SCB resistance.

Visual Assessment for Detection of Diffusion Depth under External Sulfate Attack in Concrete

Abstract This paper describes two visual approaches, namely an area ratio method and a grayscale variation method, to evaluate the effective diffusion depth inside cement-based systems when subjected to external sulfate attack. The former is based on the calculation of the amount of pixels within two areas, namely the area of cross section and the undiffused area, while the latter is per the normalized color variation. Three types of binder, all conforming to the Canadian Standards Association (CSA), were employed to produce three batches of cylindrical specimens, which were immersed in a sulfate-rich environment for up to 12 wk. The effective diffusion depths, obtained by the two visual approaches described here, were compared with the sulfate content found experimentally through chemical titration. The results show that the proposed visual methods can capture the effective diffusion depths inside cement-based systems after exposure to sulfate attack. The maximum value ranged from 7.0 to 11.0 mm over 12 wk of exposure. The proposed visual techniques enable a quick assessment to decide whether further repair is warranted.

Dissolved inorganic nutrient enrichment does not affect sponge growth or condition

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 634:77-88 (2020) - DOI: https://doi.org/10.3354/meps13184 Dissolved inorganic nutrient enrichment does not affect sponge growth or condition Blake D. Ramsby1,2,3,*, Joshua Heishman3,4, Mia O. Hoogenboom1, Steve Whalan5, Nicole S. Webster2,3,6 1College of Science and Engineering and ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland 4811, Australia 2Australian Institute of Marine Science, Townsville, Queensland 4810, Australia 3AIMS@JCU, Australian Institute of Marine Science and James Cook University, Townsville, Queensland 4811, Australia 4Department of Biological Sciences, College of Science, Purdue University, West Lafayette, Indiana 47907, USA 5Marine Ecology Research Centre, School of Environment, Science and Engineering, Southern Cross University, Lismore, New South Wales 2480, Australia 6Australian Centre for Ecogenomics, The University of Queensland, St Lucia, Queensland 4072, Australia *Corresponding author: blake.ramsby@my.jcu.edu.au ABSTRACT: Changing land use and an increasing human population have led to increased terrestrial runoff, which delivers nutrients, pesticides, and heavy metals into aquatic ecosystems. Elevated nutrient levels can adversely affect nearshore corals by reducing the amount of light reaching the benthos, exacerbating coral disease and bleaching, as well as stimulating algal growth, but the effects on other reef taxa are poorly understood. We investigated the effects of dissolved inorganic nutrient enrichment and changes in irradiance on the growth and condition of 5 common Great Barrier Reef sponges: 4 sponges with photosynthetic symbionts and 1 lacking photosynthetic symbionts. Concentrations of up to 7 µM total dissolved inorganic nitrogen (DIN) did not significantly affect the growth, condition, or chl a content of any sponge species after 10 wk exposure. However, 2 species lost >20% volume across all nutrient treatments, suggesting that aquarium conditions may have been suboptimal for these species. Irradiance (80 vs. 160 µmol quanta m-2 s-1) did not affect 4 of the 5 sponge species; however, higher irradiance resulted in higher organic content and chl a levels in the bioeroding sponge Cliona orientalis, the only studied species that associates with the photosynthetic dinoflagellate Symbiodinium, suggesting that sponge-Symbiodinium associations may be more sensitive to irradiance levels than sponge-Cyanobacteria associations. While elevated nutrient levels are exacerbating the decline of reef-building corals, exposure to the average DIN levels within flood plumes that reach inshore reefs appears to have negligible effects on reef sponges. KEY WORDS: Nitrogen · Phosphorus · Light · Pollution Full text in pdf format Supplementary material PreviousNextCite this article as: Ramsby BD, Heishman J, Hoogenboom MO, Whalan S, Webster NS (2020) Dissolved inorganic nutrient enrichment does not affect sponge growth or condition. Mar Ecol Prog Ser 634:77-88. https://doi.org/10.3354/meps13184 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 634. Online publication date: January 23, 2020 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2020 Inter-Research.

Impacts of Subchronic, High-Level Noise Exposure on Sleep and Metabolic Parameters: A Juvenile Rodent Model.

Background:Noise is an environmental factor that has been associated with metabolic and sleep disorders. Sleep is a vital function, since it underpins physiologic processes and cognitive recovery and development. However, the effects of chronic noise exposure on the developing organism are still subject to debate.Objective:The objective of the present study was to assess the effects of subchronic, high-level noise exposure on sleep, apnea, and homeostasis in juvenile rats.Methods:Twenty-four 3-wk-old male Wistar rats were exposed to noise [, ] for 5 wk and 2 d during the 12-h rest period. Data on sleep stages, food and water intake, apnea, and body and organ weight were recorded.Results:Five weeks of high-level noise exposure were associated with hyperphagia (), body weight gain (), a heavier thymus (), and heavier adrenal glands (). A sleep analysis highlighted microstructural differences in the active period: in particular, the mean daily amount of rapid eye movement (REM) sleep as a proportion of total sleep time (TST) was higher. The mean daily amount of non-REM (NREM) sleep was lower in the exposed group, meaning that the intergroup difference in the TST was not significant. During a 1-h, noise-free plethysmographic recording during the rest period, the mean total amount of active wakefulness (AW) was lower in the exposed group (by 9.1 min), whereas the mean duration of an episode of REM sleep was higher (by 1.8 min), and the TST was higher (by 10.7 min).Discussion:Subchronic exposure of juvenile rats to high-intensity noise during the rest period was associated with some small but significant sleep disturbances, greater food and water intakes, greater body weight gain, and greater thymus and adrenal gland weights. The main effects of noise exposure on sleep were also observed in the 1-h plethysmography session after 5 wk of exposure. https://doi.org/10.1289/EHP4045

Exposure to Secondhand Smoke and Arrhythmogenic Cardiac Alternans in a Mouse Model.

Background:Epidemiological evidence suggests that a majority of deaths attributed to secondhand smoke (SHS) exposure are cardiovascular related. However, to our knowledge, the impact of SHS on cardiac electrophysiology, handling, and arrhythmia risk has not been studied.Objectives:The purpose of this study was to investigate the impact of an environmentally relevant concentration of SHS on cardiac electrophysiology and indicators of arrhythmia.Methods:Male C57BL/6 mice were exposed to SHS [total suspended particles (THS): , nicotine: , carbon monoxide: , or filtered air (FA) for 4, 8, or 12 wk (]. Hearts were excised and Langendorff perfused for dual optical mapping with voltage- and -sensitive dyes.Results:At slow pacing rates, SHS exposure did not alter baseline electrophysiological parameters. With increasing pacing frequency, action potential duration (APD), and intracellular alternans magnitude progressively increased in all groups. At 4 and 8 wk, there were no statistical differences in APD or alternans magnitude between SHS and FA groups. At 12 wk, both APD and alternans magnitude were significantly increased in the SHS compared to FA group (). SHS exposure did not impact the time constant of transient decay () at any exposure time point. At 12 wk exposure, the recovery of transient amplitude with premature stimuli was slightly (but nonsignificantly) delayed in SHS compared to FA hearts, suggesting that release via ryanodine receptors may be impaired.Conclusions:In male mice, chronic exposure to SHS at levels relevant to social situations in humans increased their susceptibility to cardiac alternans, a known precursor to ventricular arrhythmia. https://doi.org/10.1289/EHP3664

Efficacy of Entomopathogenic Fungal Products for Biological Control of Spotted Wing Drosophila (Diptera: Drosophilidae) under Laboratory Conditions

Spotted wing drosophila, Drosophila suzukii Matsumura (Diptera: Drosophilidae), is a major pest of bushberries, caneberries, and other thinskinned fruits around the world. Current control programs rely solely on the use of frequent insecticide applications. Entomopathogenic fungi have shown some efficacy for tephritid fruit flies and D. suzukii. In this study, formulated products BotaniGard ES (Beauveria bassiana), and PFR-97 20% WDG (Isaria fumosorosea) were evaluated for efficacy on adult D. suzukii in laboratory fruit-dip studies. Blueberry fruits were dipped in high and low label rates of each fungal suspension before exposure to D. suzukii. Mortality was assessed at 24, 48, 72, and 168 h (1 wk) after D. suzukii release. After 1 wk exposure, the remaining live flies, dead flies, and fruit were removed from containers. The live flies were discarded whereas dead flies were placed in separate containers and checked for mycosis after 1 wk. Fruits were placed in small solo cups with lids and checked after 2 wk for emergence of D. suzukii. The high rate of BotaniGard ES caused significant mortality after 24 h and both rates of BotaniGard ES reduced emergence from fruit compared with the control. BotaniGard ES may be useful in rotation with other effective compounds, but further research under field conditions is needed to confirm this finding.

Response of the mayfly (Cloeon dipterum) to chronic exposure to thiamethoxam in outdoor mesocosms

Thiamethoxam is a widely used neonicotinoid insecticide that has been detected in surface water monitoring programs in North America and Europe. This has led to questions about its toxicity to nontarget insects, specifically those with an aquatic life stage. To address the uncertainty associated with possible impacts from environmental exposures, a chronic (35-d) outdoor mesocosm study with a formulated product containing thiamethoxam was conducted. The specific focus of the study was the response of mayflies (Ephemeroptera), which have been reported to be particularly sensitive in laboratory studies. A range of concentrations (nominally 0.1, 0.3, 1.0, 3.0, and 10.0 µg/L thiamethoxam), plus untreated controls were tested, and the abundance and emergence of mayflies (Cloeon dipterum) were assessed weekly for 35 d. Mean measured time-weighted average exposures were within 6% of nominal over the duration of the study, with the mean half-life of thiamethoxam in each treatment ranging from 7 to 13 d. Statistically significant reductions in both larval abundance and adult emergence were observed at 10.0, 3.0, and 1.0 μg/L following 1, 2, and 3 wk of exposure, respectively. Exposure to 0.1 and 0.3 µg/L thiamethoxam had no statistically significant effect on larval mayfly abundance or adult emergence at any point in the study. These findings support a 35-d no-observed-effect concentration (NOEC) of 0.3 µg thiamethoxam/L for mayflies (C. dipterum) under chronic conditions. Furthermore, because the 95th percentile of environmental concentrations has been reported to be 0.054 µg/L, these results indicate that populations of C. dipterum and similarly sensitive aquatic insects are unlikely to be significantly impacted by thiamethoxam exposure in natural systems represented by the conditions in our study. Environ Toxicol Chem 2018;37:1040-1050. © 2017 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

Longevity of Fly Baits Exposed to Field Conditions

Insecticidal fly baits are important tools for adult house fly, Musca domestica L. (Diptera: Muscidae), control, especially on animal operations. Two house fly baits, containing either cyantraniliprole or dinotefuran, were tested on a dairy farm for attractiveness over time compared to a sugar control. Sticky trap and bucket trap house fly catches were recorded for each bait type at 1 h, 3 h, 6 h, 12 h, 24 h, 48 h, 72 h, and 168 h. After 1 wk of exposure to flies and field conditions, these 'aged' baits were tested against fresh baits for fly visitation in the field over 1 h. House flies from each bait type (aged and fresh) were collected and kept under laboratory conditions to assess mortality over 3 d. Average visitation of individual flies to each bait type (fresh) in the field was also evaluated. Sticky traps did not show significant fly catch differences among bait types over time, however bucket trap catches did show significant differences for cyantraniliprole bait and dinotefuran bait compared to sugar at 72 h and 168 h. No significant differences among fly visitation to aged or fresh baits were found. Fresh cyantraniliprole bait and dinotefuran bait resulted in greater fly mortality compared to controls, but not compared to aged toxic baits. Average house fly visitation time was greatest for sugar and cyantraniliprole bait.

Thiamethoxam honey bee colony feeding study: Linking effects at the level of the individual to those at the colony level.

Neonicotinoid insecticides have been used globally on a wide range of crops through seed treatment as well as soil and foliar applications and have been increasingly studied in relation to the potential risk to bees because of their detection in pollen and nectar of bee-attractive crops. The present article reports the results of laboratory studies (10-d adult and 22-d larval toxicity studies assessing the chronic toxicity of thiamethoxam to adult honey bees and larvae, respectively) and a colony feeding study, with 6 wk of exposure in an area with limited alternative forage, to provide a prewintering colony-level endpoint. The endpoints following exposure of individuals in the laboratory (10-d adult chronic no-observed-effect concentration [NOEC] for mortality 117 μg thiamethoxam/kg sucrose solution, 141 μg thiamethoxam/L sucrose solution; 22-d larval chronic NOEC 102 μg thiamethoxam/kg diet) are compared with those generated at the colony level, which incorporates sublethal effects (no-observed-adverse-effect concentration [NOAEC] 50 μg thiamethoxam/L sucrose solution, 43 μg thiamethoxam/kg sucrose solution). The data for sucrose-fed honey bee colonies support the lack of effects identified in previous colony-level field studies with thiamethoxam. However, unlike these field studies demonstrating no effects, colony feeding study data also provide a threshold level of exposure likely to result in adverse effects on the colony in the absence of alternative forage, and a basis by which to evaluate the potential risk of thiamethoxam residues detected in pollen, nectar, or water following treatment of bee-attractive crops. Environ Toxicol Chem 2018;37:816-828. © 2017 SETAC.

The tumor suppressor phosphatase and tensin homolog protein (PTEN) is negatively regulated by NF-κb p50 homodimers and involves histone 3 methylation/deacetylation in UROtsa cells chronically exposed to monomethylarsonous acid

UROtsa cells have been accepted as a model to study carcinogenicity mechanisms of arsenic-associated human bladder cancer. In vitro continuous exposure to monomethylarsonous acid (MMAIII), leads UROtsa cells to commit to malignant transformation. In this process, NF-κβ-associated inflammatory response seems to play an important role since this transcription factor activates some minutes after cells are exposed in vitro to MMAIII and keeps activated during the cellular malignant transformation. It is known that a slight decrease in the protein phosphatase and tensin homologue (PTEN) gene expression is enough for some cells to become malignantly transformed. Interestingly, this tumor suppressor has been proven to be negatively regulated by NF-κβ through binding to its gene promoter. Based on these observations we propose that NF-κβ may be involved in arsenic associated carcinogenesis through the negative regulation of PTEN gene expression. Changes in PTEN expression and the binding of p50 NF-κβ subunit to PTEN promoter were evaluated in UROtsa cells exposed for 4, 12, 20, or 24 wk to 50nM MMAIII. Results showed that MMAIII induced a significant decrease in PTEN expression around 20 wk exposure to MMAIII,which correlated with increased binding of p50 subunit to the PTEN promoter. Consistent with these results, ChIP assays also showed a significant decrease in H3 acetylation (H3ac) but an increase in the repression marks H3k9me3 and H327me3 in PTEN promoter when compared with not treated cells. These results suggest that the activation of NF-κβ by MMAIII may participate in UROtsa cells malignant transformation through the negative regulation of PTEN expression involving p50 homodimers-mediated chromatin remodeling around the PTEN promoter.

Oyster (Crassostrea virginica [Gmelin, 1791]) Mortality at Prolonged Exposures to High Temperature and Low Salinity

ABSTRACT Mortality of two size classes ( 35 mm) of eastern oysters Crassostrea virginica when exposed to combinations of low salinity (1, 2, 3, and 4) for extended periods (up to 30 days) at summer water temperatures typical of the Virginia Chesapeake Bay subestuaries was examined. A critical salinity-temperature combination of less than two at greater than 28°C for more than 1 wk exposure for oyster mortality is suggested. A review of limited historical salinity-temperature tolerance data suggest selection of local populations of oysters having differing salinity tolerances. Such selection may prove critical to persistence of low-salinity populations in the Chesapeake Bay subestuaries with projected climate change.

Evaluating the effects of diel-cycling hypoxia and pH on growth and survival of juvenile summer flounder Paralichthys dentatus

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 556:223-235 (2016) - DOI: https://doi.org/10.3354/meps11817 Evaluating the effects of diel-cycling hypoxia and pH on growth and survival of juvenile summer flounder Paralichthys dentatus Max I. Davidson1,*, Timothy E. Targett1, Paul A. Grecay2 1University of Delaware, College of Earth, Ocean and Environment, School of Marine Science and Policy, Lewes, DE 19958, USA 2Salisbury University, Department of Biological Sciences, Salisbury, MD 21801, USA *Corresponding author: maxiandavidson@gmail.com ABSTRACT: Effects of diel-cycling dissolved oxygen (DO) and pH on young-of-the-year summer flounder Paralichthys dentatus were examined in laboratory experiments. Flounder were exposed to 2 cycling DO levels (extreme = 1-11 mg O2 l-1; moderate = 3-9 mg O2 l-1), 2 cycling pH levels (extreme = 6.8-8.1; moderate = 7.2-7.8), and static normoxia (7.5 mg O2 l-1) and pH (7.5) in a fully crossed 3 × 3 experimental design for 20 d. Cycling conditions reflected summertime DO and pH fluctuations in flounder nursery habitat. Experiments were conducted over 3 partial factorial trials. Growth was significantly reduced in fish exposed to the most extreme diel-cycling DO, across all pH treatments, with no consistent growth reduction in other treatments. Cycling treatments with mean daily low pH (~6.87) and high pCO2 (~10000 µatm) had neither an independent nor interactive effect, with hypoxia, on growth. Flounder exhibited growth rate recovery. Following initial growth reduction when exposed to extreme diel-cycling hypoxia and pH over Days 1-10, growth increased ~2-fold under static DO (7.5 mg O2 l-1) and pH (7.5) conditions over the following 10 d. Flounder did not exhibit growth rate acclimation, defined as increased growth during prolonged exposure, under extreme diel-cycling DO and pH for 20 d. Flounder experienced mortality (>90% of individuals) after 2-3 wk exposure to extreme diel-cycling DO and pH. These experimental results demonstrate that extreme diel-cycling DO and pH can significantly impact summer flounder growth and survival and that the growth rate reduction is driven by DO. KEY WORDS: Diel-cycling hypoxia · Diel-cycling pH · Eutrophication · Flounder · Hypoxia · Ocean acidification Full text in pdf format PreviousNextCite this article as: Davidson MI, Targett TE, Grecay PA (2016) Evaluating the effects of diel-cycling hypoxia and pH on growth and survival of juvenile summer flounder Paralichthys dentatus. Mar Ecol Prog Ser 556:223-235. https://doi.org/10.3354/meps11817 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 556. Online publication date: September 08, 2016 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2016 Inter-Research.

Exposure to a PBDE/OH-BDE mixture alters juvenile zebrafish (Danio rerio) development.

Polybrominated diphenyl ethers (PBDEs) and their metabolites (e.g., hydroxylated BDEs [OH-BDEs]) are contaminants frequently detected together in human tissues and are structurally similar to thyroid hormones. Thyroid hormones partially mediate metamorphic transitions between life stages in zebrafish, making this a critical developmental window that may be vulnerable to chemicals disrupting thyroid signaling. In the present study, zebrafish were exposed to 6-OH-BDE-47 (30 nM; 15 μg/L) alone, or to a low-dose (30 μg/L) or high-dose (600 μg/L) mixture of PentaBDEs, 6-OH-BDE-47 (0.5-6 μg/L), and 2,4,6-tribromophenol (5-100 μg/L) during juvenile development (9-23 d postfertilization) and evaluated for developmental endpoints mediated by thyroid hormone signaling. Fish were sampled at 3 time points and examined for developmental and skeletal morphology, apical thyroid and skeletal gene markers, and modifications in swimming behavior (as adults). Exposure to the high-dose mixture resulted in >85% mortality within 1 wk of exposure, despite being below reported acute toxicity thresholds for individual congeners. The low-dose mixture and 6-OH-BDE-47 groups exhibited reductions in body length and delayed maturation, specifically relating to swim bladder, fin, and pigmentation development. Reduced skeletal ossification was also observed in 6-OH-BDE-47-treated fish. Assessment of thyroid and osteochondral gene regulatory networks demonstrated significantly increased expression of genes that regulate skeletal development and thyroid hormones. Overall, these results indicate that exposures to PBDE/OH-BDE mixtures adversely impact zebrafish maturation during metamorphosis. Environ Toxicol Chem 2017;36:36-48. © 2016 SETAC.

Kelp in hot water: II. Effects of warming seawater temperature on kelp quality as a food source and settlement substrate

ABSTRACT: Predicting the effect of climate change on communities requires an understanding ofthe effects of environmental conditions on species and their interactions. We investigated thepotential for warming seawater temperature to modify the interactions of the gastropod meso-grazer Lacuna vincta and the invasive bryozoan Membranipora membranacea with kelps in NovaScotia. The nutritional content (C/N) of the kelps Saccharina latissima, Laminaria digitata andAgarum clathratum were unaffected by temperature (11, 18 and 21°C), and chemical defenses(phlorotannins) were reduced only in A. clathratum after 1 wk exposure to 21°C. C/N and phloro-tannin content increased over the season in S. latissima collected monthly in summer 2013 and2014. The effect of temperature-induced changes in kelp on the grazing of L. vincta was assessedusing feeding experiments with S. latissima pretreated at 11 or 21°C. Snails consumed more kelppretreated at 21°C only when grazing rate was high. The quality of S. latissima as a food sourcefor L. vincta was not affected by temperature, as diets of kelp pretreated at 11 and 21°C supportedsimilar growth, reproduction, and survival of snails. Temperature also did not affect the quality ofkelp as a substrate for M. membranacea, since settlement rates were not different betweenS. latissima pretreated at ambient temperature (9 to 14) and 21°C. The absence of temperature-induced changes in kelp quality suggests that the effects of L. vincta and M. membranacea will actadditively with the direct effects of temperature and cause increased biomass loss from kelp beds.KEY WORDS: Kelp · Climate change · Temperature · Saccharina latissima · Lacuna vincta ·Herbivory · Membranipora membranacea · Bryozoans

Identification and characterisation of an ostreid herpesvirus-1 microvariant (OsHV-1 µ-var) in Crassostrea gigas (Pacific oysters) in Australia

Between November 2010 and January 2011, triploid Crassostrea gigas (Pacific oysters) cultivated in the Georges River, New South Wales, experienced >95% mortality. Mortalities also occurred in wild diploid C. gigas in the Georges River and shortly thereafter in the adjacent Parramatta River estuary upstream from Sydney Harbour. Neighbouring Saccostrea glomerata (Sydney rock oysters) did not experience mortalities in either estuary. Surviving oysters were collected to investigate the cause of mortalities. Histologically all oysters displayed significant pathology, and molecular testing revealed a high prevalence of ostreid herpesvirus-1 (OsHV-1). Quantitative PCR indicated that many C. gigas were carrying a high viral load at the time of sampling, while the load in S. glomerata was significantly lower (p < 0.001). Subsequent in situ hybridisation experiments confirmed the presence of a herpesvirus in C. gigas but not S. glomerata tissues, suggesting that S. glomerata is not susceptible to infection with OsHV-1. Naïve sentinel triploid C. gigas placed in the Georges River estuary in January 2011 quickly became infected and experienced nearly 100% mortality within 2 wk of exposure, indicating the persistence of the virus in the environment. Phylogenetic analysis of sequences derived from the C2/C6 region of the virus revealed that the Australian strain of OsHV-1 belongs to the microvariant (µ-var) cluster, which has been associated with severe mortalities in C. gigas in other countries since 2008. Environmental data revealed that the Woolooware Bay outbreaks occurred during a time of considerable environmental disturbance, with increased water temperatures, heavy rainfall, a toxic phytoplankton bloom and the presence of a pathogenic Vibrio sp. all potentially contributing to oyster stress. This is the first confirmed report of OsHV-1 µ-var related C. gigas mortalities in Australia.

Heart stopping tick

Although Lyme carditis is relatively rare within 4-6 wk of exposure, it can uncommonly present as the first sign of disseminated Lyme disease. Here we present 17 year old boy who presented to the emergency department with chest discomfort and was later found to have complete atrioventricular block due to lyme carditis. He had uneventful recovery after empiric treatment with ceftriaxone. Our case highlights the importance of considering reversible causes of complete AV block since appropriate therapy can avoid the need for permanent pacemaker insertion.

High-Fat Diet-Induced Alterations in the Feeding Suppression of Low-Dose Nisoxetine, a Selective Norepinephrine Reuptake Inhibitor

Central noradrenergic pathways are involved in feeding and cardiovascular control, physiological processes altered by obesity. The present studies determined how high-fat feeding and body weight gain alter the sensitivity to the feeding suppression and neural activation to a selective norepinephrine reuptake inhibitor, nisoxetine. Acute administration of nisoxetine (saline: 0, 3, 10, and 30 mg/kg; IP) resulted in a dose-dependent reduction in the 24 h refeeding response in male Sprague Dawley rats maintained on standard chow. In a similar fashion, nisoxetine resulted in reductions in blood pressure and a compensatory increase in heart rate. From these studies, the 3 mg/kg dose was subthreshold. In a separate experiment, however, 10 wk exposure to a high-fat diet (60% fat) resulted in weight gain and significant feeding suppression following administration of nisoxetine (3 mg/kg) compared with animals fed a control diet (10% fat). Nisoxetine (3 mg/kg) also resulted in greater neural activation, as measured by c-Fos immunohistochemistry, in the arcuate nucleus of the hypothalamus in animals exposed to the high-fat diet. Such data indicate acute nisoxetine doses that suppress food intake can impact cardiovascular measures. It also suggests that the feeding suppression to a low-dose nisoxetine is enhanced as a result of high-fat diet and weight gain.