Exposure of female lobsters to sediments spiked with emamectin benzoate: Effects on eggs and larvae early development.

The salmon aquaculture industry is an important economic activity established on both the west and east coast of Canada. To control sea lice infestations, in-feed products like emamectin benzoate (EMB) are widely used. Due to its low solubility and persistence EMB can accumulate in marine sediments and be potentially bioavailable to non-target organisms from months to years. The American lobster (Homarus americanus) is a key species in the Northwest Atlantic with high economic and ecological value. It may be exposed to therapeutants considering lobster habitats overlap with aquaculture locations requiring a better understanding of the potential impact of these therapeutants through varied pathways of exposure. In this study, we investigated the exposure of gravid female lobsters to EMB spiked sediment to mimic the likely presence of these females at aquaculture sites for a 10-day period. We completed testing by assessing EMB effects on adult molting and quality, embryo hatching rates, and larval offspring quality and larval molting. Our results show that a single, 10-day exposure of ovigerous females to EMB concentrations higher than environmentally relevant values did not affect females or their offspring.

Considerations and data update for the inference of environmental quality standards for two avermectins widely used in salmon aquaculture.

We have updated and reviewed toxicity data for Emamectin benzoate (EMB) and Ivermectin (IVER), two in-feed drugs used to treat sea lice in farmed Atlantic salmon, and inferred new Environmental Quality Standards (EQS) using a deterministic approach or Species Sensitivity Distributions (SSDs) based on available data. We used a SSD model averaging approach and inferred a water acute EQS value of 24.9 ng/L (SSD) for EMB, while previously established chronic water EQS of 0.17 ng/L and sediment benthic EQS of 131 ng/kg dry weight remained unchanged. For IVER, both a water acute EQS of 8.04 ng/L and a chronic water EQS of 3.98 ng/L were inferred using SSDs as well as a benthic EQS of 290 ng/kg dry weight using a deterministic approach. In light of the lack of solubility and tendency of both avermectins to sorb to material benthic EQSs remain the most relevant value to consider for regulators.

The persistence of emamectin benzoate in marine sediments with different organic matter regimes, temperature conditions, and antibiotic presence.

The objectives of this 318-day study are to determine half-lives of the anti-sea lice medication emamectin benzoate (EMB) under conditions present in sediments at aquaculture sites and document the degradation of EMB into its main metabolite desmethyl emamectin benzoate (DES). Tested conditions include different matrix types (sand, mud), two temperatures (4, 10 degrees), organic matter presence (fish feed waste and feces), and the presence of oxytetracycline. We document a transformation ratio of EMB to DES of 0.16 to 4.4 % and show that the co-presence of oxytetracycline increases EMB calculated half-lives to values >6000 days for mud matrices. EMB incubated in high organic enrichment regimes was not observed to degrade at 4 degrees. Multivariate analyses show interactions between sediment conditions (matrix, temperature, organic matter [OM], oxytetracycline) influence EMB persistence and DES:EMB ratios. Ranges of EMB half-lives and information on metabolites can be used to anticipate potential effects on marine communities.

Relationship between in feed drugs, antibiotics and organic enrichment in marine sediments at Canadian Atlantic salmon aquaculture sites.

The presence of in-feed anti-sea lice drugs and their relationship with organic enrichment is poorly understood in sediment surrounding salmon farms. Using data from an aquaculture monitoring program (2018-2020), we describe this relationship at ten sites in four Canadian provinces. Three anti-sea lice pesticides (lufenuron, teflubenzuron, emamectin benzoate and metabolite desmethyl emamectin benzoate), and one antibiotic (oxytetracycline) were detected. Concentrations were often below limits of quantification. Values are also lower than those reported in other aquaculture salmon-producing countries. Highest concentrations, along with organic enrichment, were observed ~200 m of cages with lower concentrations detected up to 1.5 km away. Most samples had at least two drugs present: 75.2 % (British Columbia), 91.4 % (Newfoundland), and 54.8 % (New Brunswick/Nova Scotia) highlighting the potential for cumulative effects. Emamectin benzoate and oxytetracycline were detected four and three years respectively after last known treatments, demonstrating the need for research on overall persistence of compounds.

Species sensitivity distributions for two widely used anti-sea lice chemotherapeutants in the salmon aquaculture industry.

The main objective of the present study is to construct acute aquatic species sensitivity distributions (SSD) and generate proposed HC5 values (i.e. the hazardous concentration for which 5 % of species are affected or potentially affected) for two aquaculture anti-sea lice bath pesticides, azamethiphos, and hydrogen peroxide. These values could be used as the basis for the establishment of environmental quality standards (EQS). We have generated SSDs and inferred HC5 values for mortality and sublethal endpoints using LC50, EC50, and NOEC/LOEC data points separately and for each bath pesticide. Through the examination of literature data on the toxicity of both compounds, we opted to use tests with limited exposure times to ensure environmental relevance for bath pesticides. We also separated life stages for some of the sensitive taxa to account for differences in sensitivities and risk of exposure. The resulting threshold concentrations in environmental seawater are 0.10 µg/L for azamethiphos and 0.15 mg/L for hydrogen peroxide. These suggested azamethiphos and hydrogen peroxide thresholds are comparable to some previously reported EQS values. Further considerations need to be included in how to better use these thresholds in a regulatory context in relation to dispersion patterns. It is also clear that delayed mortality and sublethal effects documented in the literature require further study to fully anticipate the environmental risks of using these two bath pesticides.

Metabolization of emamectin benzoate into desmethyl emamectin benzoate in spiked marine sediments.

Emamectin benzoate (EMB) (4″deoxy- 4″-epi-methylaminoavermectin) is a pesticide developed to control pests on various crops, and in forestry. It is also used in salmon aquaculture to control sea lice infestations as an in-feed therapeutant. Little is known about EMB metabolites and potential associated toxicities in marine sediments. In this study, we used natural marine sediments (sand and mud) fortified at an EMB concentration of 60 ppb (wet weight). Results show an almost immediate transformation of EMB to Desmethyl EMB (DES) with no increased rates of metabolization when stored sediment samples were incubated for up to 16 h. The transformation ratio of EMB to DES represented between 0.16 and 0.39% of EMB; values are lower than what has been observed in fish tissue. Data suggest that DES is generated through both abiotic (tested after autoclaving marine sediments) and biological processes. Further work on freshly sampled marine sediments with EMB deposits, different organic regimes, and a detailed assessment of active bacterial communities are necessary to better evaluate the EMB to DES rate of transformation around aquaculture sites.

Adolescents' knowledge of a peer's non-suicidal self-injury and own non-suicidal self-injury and suicidality.

OBJECTIVE: Some research suggests that suicidal ideation and attempt among adolescents may be contagious - that is adolescents who are exposed to peers' suicidal behaviour are more likely to experience suicidal ideation or attempt suicide themselves. Less is known about the potential contagion effect of non-suicidal self-injury (NSSI). Our objective was to determine whether knowledge of a friend's NSSI is associated with adolescent's own non-suicidal self-injury and suicidal behaviours. METHODS: Data from 1483 youth ages 14-17 years were obtained from the 2014 Ontario Child Health Study, a cross-sectional population-based survey of children and adolescents in Ontario, Canada. Logistic regression models were used to examine associations between knowledge of a friend's NSSI and adolescents' own self-reported self-injurious and suicidal behaviours. Interactions with gender, age group and presence of a mental disorder were investigated. RESULTS: Knowledge of a friend's non-suicidal self-injury was significantly associated with the adolescent's own non-suicidal self-injury (OR = 2.03, 95% CI 1.05-3.90), suicidal ideation (OR = 3.08, 95% CI 1.50-6.30) and suicide attempt (OR = 2.87, 95% CI 1.20-6.87). CONCLUSION: These findings suggest an apparent contagion effect for non-suicidal self-injury. Awareness of a friend's self-injurious behaviours is associated with an adolescent's own self-injury and suicidality. Interventions aimed at preventing NSSI and suicidality should consider prevention of possible contagion at the school and/or community level.

Lifetime experience of multiple common mental disorders and 19-year mortality: results from a Canadian population-based cohort.

AIMS: To examine the impact of multiple psychiatric disorders over the lifetime on risk of mortality in the general population. METHODS: Data came from a random community-based sample of 1397 adults in Atlantic Canada, recruited in 1992. Major depression, dysthymia, panic disorder, generalised anxiety disorder and alcohol use disorders were assessed using the Diagnostic Interview Schedule (DIS). Vital status of participants through 2011 was determined using probabilistic linkages to the Canadian Mortality Database. Cox proportional hazard models with age at study entry as the time scale were used to investigate the relationship between DIS diagnoses and mortality, adjusted for participant education, smoking and obesity at baseline. RESULTS: Results suggested that mood and anxiety disorders rarely presented in isolation - the majority of participants experienced multiple psychiatric disorders over the lifetime. Elevated risk of death was found among men with both major depression and dysthymia (HR 2.56; 95% CI 1.12-5.89), depression and alcohol use disorders (HR 2.45; 95% CI 1.18-5.10) and among men and women who experienced both panic disorder and alcohol use disorders (HR 3.80; 95% CI 1.19-12.16). CONCLUSION: The experience of multiple mental disorders over the lifetime is extremely common, and associated with increased risk of mortality, most notably among men. Clinicians should be aware of the importance of considering contemporaneous symptoms of multiple psychiatric conditions.

Consistency in adult reporting of adverse childhood experiences.

BACKGROUND: Many studies have used retrospective reports to assess the long-term consequences of early life stress. However, current individual characteristics and experiences may bias the recall of these reports. In particular, depressed mood may increase the likelihood of recall of negative experiences. The aim of the study was to assess whether specific factors are associated with consistency in the reporting of childhood adverse experiences. METHOD: The sample comprised 7466 adults from Canada's National Population Health Survey who had reported on seven childhood adverse experiences in 1994/1995 and 2006/2007. Logistic regression was used to explore differences between those who consistently reported adverse experiences and those whose reports were inconsistent. RESULTS: Among those retrospectively reporting on childhood traumatic experiences in 1994/1995 and 2006/2007, 39% were inconsistent in their reports of these experiences. The development of depression, increasing levels of psychological distress, as well as increasing work and chronic stress were associated with an increasing likelihood of reporting a childhood adverse experience in 2006/2007 that had not been previously reported. Increases in mastery were associated with reduced likelihood of new reporting of a childhood adverse experience in 2006/2007. The development of depression and increases in chronic stress and psychological distress were also associated with reduced likelihood of 'forgetting' a previously reported event. CONCLUSIONS: Concurrent mental health factors may influence the reporting of traumatic childhood experiences. Studies that use retrospective reporting to estimate associations between childhood adversity and adult outcomes associated with mental health may be biased.

Trajectories of childhood neighbourhood cohesion and adolescent mental health: evidence from a national Canadian cohort.

BACKGROUND: The objective of this study was to examine associations between trajectories of childhood neighbourhood social cohesion and adolescent mental health and behaviour. METHOD: This study used data from the National Longitudinal Survey of Children and Youth, a nationally representative sample of Canadian children. The sample included 5577 children aged 0-3 years in 1994-1995, prospectively followed until age 12-15 years. Parental perceived neighbourhood cohesion was assessed every 2 years. Latent growth class modelling was used to identify trajectories of neighbourhood cohesion. Mental health and behavioural outcomes were self-reported at age 12-15 years. Logistic regression was used to examine associations between neighbourhood cohesion trajectories and outcomes, adjusting for potential confounders. RESULTS: Five distinct trajectories were identified: 'stable low' (4.2%); 'moderate increasing' (9.1%); 'stable moderate' (68.5%); 'high falling' (8.9%); and 'stable high' (9.3%). Relative to those living in stable moderately cohesive neighbourhoods, those in stable low cohesive neighbourhoods were more likely to experience symptoms of anxiety/depression [odds ratio (OR) = 1.73, 95% confidence interval (CI) 1.04-2.90] and engage in indirect aggression (OR = 1.62, 95% CI 1.07-2.45). Those with improvements in neighbourhood cohesion had significantly lower odds of hyperactivity (OR = 0.67, 95% CI 0.46-0.98) and indirect aggression (OR = 0.69, 95% CI 0.49-0.96). In contrast, those with a decline in neighbourhood cohesion had increased odds of hyperactivity (OR = 1.67, 95% CI 1.21-2.29). Those in highly cohesive neighbourhoods in early childhood were more likely to engage in prosocial behaviour ('high falling': OR = 1.93, 95% CI 1.38-2.69; 'stable high': OR = 1.89, 95% CI 1.35-2.63). CONCLUSIONS: These results suggest that neighbourhood cohesion in childhood may have time-sensitive effects on several domains of adolescent mental health and behaviour.

Aneuploidy in the normal and diseased brain.

The brain is remarkable for its complex organization and functions, which have been historically assumed to arise from cells with identical genomes. However, recent studies have shown that the brain is in fact a complex genetic mosaic of aneuploid and euploid cells. The precise function of neural aneuploidy and mosaicism are currently being examined on multiple fronts that include contributions to cellular diversity, cellular signaling and diseases of the central nervous system (CNS). Constitutive aneuploidy in genetic diseases has proven roles in brain dysfunction, as observed in Down syndrome (trisomy 21) and mosaic variegated aneuploidy. The existence of aneuploid cells within normal individuals raises the possibility that these cells might have distinct functions in the normal and diseased brain, the latter contributing to sporadic CNS disorders including cancer. Here we review what is known about neural aneuploidy, and offer speculations on its role in diseases of the brain.

Aneuploid neurons are functionally active and integrated into brain circuitry.

The existence of aneuploid cells within the mammalian brain has suggested the influence of genetic mosaicism on normal neural circuitry. However, aneuploid cells might instead be glia, nonneural, or dying cells, which are irrelevant to direct neuronal signaling. Combining retrograde labeling with FISH for chromosome-specific loci, distantly labeled aneuploid neurons were observed in expected anatomical projection areas. Coincident labeling for immediate early gene expression indicated that these aneuploid neurons were functionally active. These results demonstrate that functioning neurons with aneuploid genomes form genetically mosaic neural circuitries as part of the normal organization of the mammalian brain.

Genetics and cell biology of lysophosphatidic acid receptor-mediated signaling during cortical neurogenesis.

Lysophosphatidic acid (LPA) is a small lysophospholipid that signals through G-protein coupled receptors (GPCRs) to mediate diverse cellular responses. Two LPA receptors, LPA(1) and LPA(2), show gene expression profiles in mouse embryonic cerebral cortex, suggesting roles for LPA signaling in cerebral cortical development. Here, we review loss-of-function and gain-of-function models that have been used to examine LPA signaling. Genetic deletion of lpa(1) or both lpa(1) and lpa(2) in mice results in 50-65% neonatal lethality, but not obvious cortical phenotypes in survivors, suggesting that compensatory signaling systems exist for regulating cortical development. A gain-of-function model, approached by increasing receptor activation through exogenous delivery of LPA, shows that LPA signaling regulates cerebral cortical growth and anatomy by affecting proliferation, differentiation and cell survival during embryonic development.

Chromosomal variation in neurons of the developing and adult mammalian nervous system.

A basic assumption about the normal nervous system is that its neurons possess identical genomes. Here we present direct evidence for genomic variability, manifested as chromosomal aneuploidy, among developing and mature neurons. Analysis of mouse embryonic cerebral cortical neuroblasts in situ detected lagging chromosomes during mitosis, suggesting the normal generation of aneuploidy in these somatic cells. Spectral karyotype analysis identified approximately 33% of neuroblasts as aneuploid. Most cells lacked one chromosome, whereas others showed hyperploidy, monosomy, and/or trisomy. The prevalence of aneuploidy was reduced by culturing cortical explants in medium containing fibroblast growth factor 2. Interphase fluorescence in situ hybridization on embryonic cortical cells supported the rate of aneuploidy observed by spectral karyotyping and detected aneuploidy in adult neurons. Our results demonstrate that genomes of developing and adult neurons can be different at the level of whole chromosomes.

Selective loss of sphingosine 1-phosphate signaling with no obvious phenotypic abnormality in mice lacking its G protein-coupled receptor, LP(B3)/EDG-3.

Sphingosine 1-phosphate (S1P) exerts diverse physiological actions by activating its cognate G protein-coupled receptors. Five S1P receptors have been identified in mammals: LP(B1)/EDG-1, LP(B2)/H218/AGR16/EDG-5, LP(B3)/EDG-3, LP(B4)/NRG-1/EDG-8, and LP(C1)/EDG-6. One of these receptors, LP(B1), has recently been shown to be essential for mouse embryonic development. Here we disrupted the lp(B3) gene in mice, resulting in the complete absence of lp(B3) gene, transcript, and LP(B3) protein. LP(B3)-null mice were viable and fertile and developed normally with no obvious phenotypic abnormality. We prepared mouse embryonic fibroblast (MEF) cells to examine effects of LP(B3) deletion on S1P-induced signal transduction pathways. Wild-type MEF cells expressed lp(B1), lp(B2), and lp(B3) but neither lp(B4) nor lp(C1), and they were highly responsive to S1P in phospholipase C (PLC) activation, adenylyl cyclase inhibition, and Rho activation. Identically prepared LP(B3)-null MEF cells showed significant decreases in PLC activation, slight decreases in adenylyl cyclase inhibition, and no change in Rho activation. Retrovirus-mediated rescue of the LP(B3) receptor in LP(B3)-null MEF cells restored S1P-dependent PLC activation and adenylyl cyclase inhibition. These results indicate a nonessential role for LP(B3) in normal development of mouse but show nonredundant cellular signaling mediated by a single type of S1P receptor.

Investigation of mechanisms that mediate reactive hyperaemia in guinea-pig hearts: role of K(ATP) channels, adenosine, nitric oxide and prostaglandins.

1. Reactive hyperaemia is a transient vasodilatation following a brief ischaemic period. ATP-dependent K(+) (K(ATP)) channels may be important in mediating this response, however it is unclear whether mitochondrial K(ATP) channels contribute to this in the heart. 2. We examined the involvement of K(ATP) channels and the relative role of mitochondrial channels as mediators of coronary reactive hyperaemia and compared them to mechanisms involving NO, prostaglandins and adenosine in the guinea-pig isolated heart. 3. Reactive hyperaemic vasodilatation (peak vasodilator response and flow debt repayment) were assessed after global zero-flow ischaemia (5 -- 120 s) in the presence of nitro-L-arginine methyl ester (L-NAME, 10(-5) M, n=9), 8-phenyltheophylline (8-PT, 10(-6) M, n=12) and indomethacin (10(-5) M, n=12). 4. Glibenclamide (10(-6) M, n=12) a non-selective K(ATP) channel inhibitor and 5-hydroxy-decanoic acid (5-HD, 10(-4) M, n=10) a selective mitochondrial K(ATP) channel inhibitor were also used. The specificity of the effects of glibenclamide and 5-HD (n=6 each) were confirmed using pinacidil (38 nmol -- 10 micromol) and diazoxide (42 nmol -- 2 micromol). Glibenclamide was most effective in blocking the hyperaemic response (by 87%, P<0.001) although 5-HD and 8-PT also had a marked effect (40% inhibition, P<0.001 and 32%, P<0.001, respectively). L-NAME and indomethacin had little effect. 5. Perfusion with L-NAME and glibenclamide significantly reduced baseline coronary flow (22%, P<0.01 and 33%, P<0.01) while 8-PT, indomethacin and 5-HD had no effect. 6. K(ATP) channels are the major mediators of the coronary reactive hyperaemic response in the guinea-pig. Although mitochondrial K(ATP) channels contribute, they appear less important than sarcolemmal channels.

Capillary filtration is reduced in lungs adapted to chronic heart failure: morphological and haemodynamic correlates.

OBJECTIVE: To determine pulmonary capillary filtration in experimental chronic heart failure and to investigate some morphological and haemodynamic mechanisms that could account for reduced filtration in lungs adapted to chronic heart failure. METHODS: We studied pulmonary capillary filtration, vascular resistances and morphology in lungs from guinea-pigs adapted to chronic heart failure. Heart failure was induced by banding of the ascending aorta (n=66) or sham control operation (n=78) in guinea-pigs which were studied at 150+/-8 days post-operation. RESULTS: Reduced cardiac output, increased systemic vascular resistance and LV end diastolic pressure and increased LV and RV weight:body weight ratio (all P<0.05) indicated chronic heart failure at 5 months following aortic banding in guinea-pigs. Lung weight was increased (61%, P<0.05) in heart failure compared with controls, but lung water content was reduced (5.5%, P<0.05), a reversal of the pattern seen acutely. Studies in isolated perfused lungs demonstrated a reduced capillary filtration coefficient (0. 018+/-0.003 vs. 0.003+/-0.002 ml min(-1)mmHg(-1)g(-1), P<0.001), increased arterial (61%) and venous resistance (50%) in heart failure lungs, P<0.05. Wall thickness:lumen ratio was increased in small (<250 microm) pulmonary arterioles (0.15+/-0.02 vs. 0.08+/-0. 01) and venules (0.06+/-0.005 vs. 0.04+/-0.002) in heart failure, P<0.01. Alveolar septal volume fractions (35.2+/-5.1 vs. 23.1+/-2.7) and septal:air-space volume ratios (60.5+/-13.6 vs. 31.9+/-5.3) were also increased in heart failure, P<0.05. CONCLUSIONS: Pulmonary adaptation to chronic heart failure is associated with vascular and alveolar remodelling that contributes to increased vascular resistance and reduced capillary filtration. These changes are likely to be important in mediating resistance to pulmonary oedema in chronic heart failure.

Altered development of visual subcortical projections following neonatal thalamic ablation in the hamster.

Previous research has demonstrated that precise patterns of axonal connectivity often develop during a series of stages characterized by pathfinding, target recognition, and address selection. This last stage involves the focusing of projections to a precisely defined region within the target. Because thalamic projections begin to innervate cortex before the latter stages are reached, these projections may be important in the establishment of adult-like patterns of cortical connectivity. To address this issue, we examined the mature corticopontine and corticospinal projections of visual cortex deprived of early thalamic input by visual thalamic ablation. Although ablations on the day of birth in hamsters did not disrupt the targeting of appropriate subcortical structures by visual cortical axons, they did alter the organization of projections within the basilar pons and spinal cord. The density and spread of visual corticopontine connections in lesioned animals was greatly increased relative to unlesioned animals, suggesting that thalamic afferents are required during address selection, when the topographic specificity of projections is established. To determine whether early visual thalamic ablation increases connectivity by stabilizing an exuberant developmental projection, we examined the normal development of visual corticopontine connections in hamsters ages postnatal days 1-17 (P1-P17). From the earliest ages, visual cortical axons innervate the pontine nucleus in regions specific to their adult projection zones and show progressive growth within these zones. At no time during development do projections exist that are equivalent to the projections found after thalamic ablation, suggesting that removal of thalamic input does not simply stabilize a developmental projection.

Endogenous and exogenous coronary vasodilatation are attenuated in cardiac hypertrophy: a morphological defect?

Reactive hyperaemia (RH) following brief ischaemia is reduced in hypertrophied hearts, and this may contribute to reduced coronary flow reserve. We studied vasodilatation during RH and in response to exogenous stimuli in control and hypertrophied hearts and explored the mechanisms underlying RH. Vascular reactivity was assessed in isolated hypertrophied hearts (55+/-3 days after aortic banding or sham operation) by constructing dose-response curves to acetylcholine (ACh), sodium nitroprusside (SNP) and adenosine. Reactive hyperaemic vasodilatation was assessed after global ischaemia (5-120 s) in the presence/absence of L -NAME, 8-phenyltheophylline (8-PT) and glibenclamide. Purine release and NO overflow in the coronary perfusate were analysed. Aortic constriction increased heart/body weight ratio (47%), myocyte size (19%) and arteriolar wall thickness (51%), all P<0.01. Coronary reserve was reduced in hypertrophy (105+/-8%v 182+/-12%, P<0.01). Dose response curves for ACh, SNP and adenosine were reduced in hypertrophy (69%, 86% and 68%, all P<0.01) v shams; however ED(50)values were unchanged. The peak flow and duration of RH were also attenuated (50%, P<0.001) in hypertrophy. While purine washout during RH was related to the duration of preceding ischaemia, nitrate washout was not. RH experiments in the presence of L -NAME, 8-PT and glibenclamide indicated that RH is mediated by combined actions of K(ATP)channels>adenosine>NO in both groups. RH is mediated by similar mechanisms in control and hypertrophied hearts. All vasodilatation was similarly attenuated in hypertrophy, independent of endothelial activation. We hypothesize that increased arteriolar wall thickness may limit vasodilator responses to all stimuli in hypertrophy.