Impact of the antidepressant Bupropion on the Dynamic Energy Budget of Daphnia magna

Psychiatric drugs are considered among the emerging contaminants of concern in ecological risk assessment, due to their potential to disrupt homeostasis in aquatic organisms. Bupropion is an antidepressant that acts by selective reuptake inhibition of norepinephrine and dopamine. Little is known about this compound's effects on aquatic organisms, despite being detected in significant concentrations in both water and biota close to waste-water treatment plants and densely populated areas. Dynamic Energy Budget (DEB) models are flexible mechanistic tools that can be applied to understand toxic effects and extrapolate individual responses to higher biological levels and under untested environmental conditions. In this work, we used the stdDEB-TKTD (an application of the DEB theory to ecotoxicology) approach to investigate the possible physiological mode of action of Bupropion on the model organism Daphnia magna. Next, Dynamic Energy Budget Individual-Based Models (DEB-IBM) were used to extrapolate the results to the population level and to predict the combined effects of Bupropion exposure and food availability on the daphnids. Our results revealed an increasing negative effect of this antidepressant on the reproduction and survival of the animals with increasing concentration (0.004, 0.058, 0.58 and 58 μM). At the population level, we found that even the lowest used doses of Bupropion could reduce the population density and its reproductive output. The impacts are predicted to be stronger under limited food conditions.

The use of muscle biomarkers for assessing physiological effects of heavy metal pollution in the greater white-toothed shrew (Crocidura russula)

The greater white-toothed shrew Crocidura russula has been used as a sentinel species for estimating environmental risks to human populations. Previous studies in mining areas have focused on the liver of shrews as the primary target of physiological and metabolic changes due to heavy metal pollution. However, populations persist even when detoxification by the liver seems to be compromised and damage is observed. These pollutant-adapted individuals inhabiting contaminated sites may exhibit altered biochemical parameters that confer increased tolerance in various tissues other than the liver. The skeletal muscle tissue of C. russula might be an alternative tissue that allows the survival of organisms inhabiting historically polluted sites due to the detoxification of redistributed metals. Organisms from two heavy metal mine populations and one population derived from an unpolluted site were used to determine the detoxification activities, antioxidant capacity, and oxidative damage, as well as cellular energy allocation parameters and acetylcholinesterase activity (a biomarker of neurotoxicity). Muscle biomarkers differ between shrews from polluted sites and shrews from the unpolluted location, with the mine animals showing: (1) a decreased energy consumption concomitant with increased energy reserves and total available energy; (2) reduced cholinergic activity, suggesting an impairment of neurotransmission at the neuromuscular junction; (3) an overall decrease in detoxification capacity and enzymatic antioxidant response and a higher level of lipid damage. Also, some of these markers differed between females and males. These changes may have resulted from a decreased detoxifying capacity of the liver and could potentially bring about significant ecological effects for this highly active species. Heavy metal pollution induced physiological changes in Crocidura russula showing that skeletal muscle may serve as a backup sink organ allowing rapid species adaptation and evolution.

Effects of Microplastic on the Population Dynamics of a Marine Copepod: Insights from a Laboratory Experiment and a Mechanistic Model

Microplastic is ubiquitously and persistently present in the marine environment, but knowledge of its population-level effects is limited. In the present study, to quantify the potential theoretical population effect of microplastic, a two-step approach was followed. First, the impact of microplastic (polyethylene, 0.995 g cm^-3 , diameter 10-45 µm) on the filtration rate of the pelagic copepod Temora longicornis was investigated under laboratory conditions. It was found that the filtration rate decreased at increasing microplastic concentrations and followed a concentration-response relationship but that at microplastic concentrations <100 particles L^-1 the filtration rate was not affected. From the concentration-response relationship between the microplastic concentrations and the individual filtration rate a median effect concentration of the individual filtration rate (48 h) of 1956 ± 311 particles L^-1 was found. In a second step, the dynamics of a T. longicornis population were simulated for realistic environmental conditions, and the effects of microplastics on the population density equilibrium were assessed. The empirical filtration rate data were incorporated in an individual-based model implementation of the dynamic energy budget theory to deduct potential theoretical population-level effects. The yearly averaged concentration at which the population equilibrium density would decrease by 50% was 593 ± 376 particles L^-1 . The theoretical effect concentrations at the population level were 4-fold lower than effect concentrations at the individual level. However, the theoretical effect concentrations at the population level remain 3-5 orders of magnitude higher than ambient microplastic concentrations. Because the present experiment was short-term laboratory-based and the results were only indirectly validated with field data, the in situ implications of microplastic pollution for the dynamics of zooplankton field populations remain to be further investigated. Environ Toxicol Chem 2022;41:1663-1674. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Evidence of micro-evolution in Crocidura russula from two abandoned heavy metal mines: potential use of Cytb, CYP1A1, and p53 as gene biomarkers

Heavy metals accumulated in the environment due to the mining industry may impact on the health of exposed wild animals with consequences at the population level via survival and selection of the most resistant individuals. The detection and quantification of shifts in gene frequencies or in the genetic structure in populations inhabiting polluted sites may be used as early indicators of environmental stress and reveal potential 'candidate gene biomarkers' for environmental health assessment. We had previously observed that specimens of the Greater white-toothed shrew (Crocidura russula) from two heavy metal mines in Southern Portugal (the Aljustrel and the Preguiça mines) carried physiological alterations compared to shrews from an unpolluted site. Here, we further investigated whether these populations showed genetic differences in genes relevant for physiological homeostasis and/or that are associated with pathways altered in animals living under chronic exposure to pollution, and which could be used as biomarkers. We analysed the mitochondrial cytochrome b (Cytb) gene and intronic and/or exonic regions of four nuclear genes: CYP1A1, LCAT, PRPF31, and p53. We observed (1) population differences in allele frequencies, types of variation, and diversity parameters in the Cytb, CYP1A1, and p53 genes; (2) purifying selection of Cytb in the mine populations; (3) genetic differentiation of the two mine populations from the reference by the p53 gene. Adding to our previous observations with Mus spretus, we provide unequivocal evidence of a population effect exerted by the contaminated environment of the mines on the local species of small mammals.

Dangerous connections: biochemical and behavioral traits in Daphnia magna and Daphnia longispina exposed to ecologically relevant amounts of paracetamol

Exposure of nontarget organisms to therapeutic agents can cause distinct toxic effects, even at low concentrations. Paracetamol is a painkiller drug, widely used in human and veterinary therapies, being frequently found in the aquatic compartment in considerable amounts. Its toxicity has already been established for some species, but its full ecotoxicological potential is still not sufficiently described. To characterize the ecotoxicity of paracetamol, the present study evaluated several parameters, such as acute immobilization (EC₅₀ calculation), biochemical alterations, and behavioral effects, in two species of freshwater microcrustaceans of the genus Daphnia (D. magna and D. longispina). To increase the relevance of the data obtained, animals were exposed to levels of paracetamol similar to those already reported to occur in the wild. Data showed antioxidant responses in both species, namely an increase of catalase and GSTs activities in D. magna. On the contrary, effects of paracetamol on D. longispina included only an impairment of GSTs activity. Despite the absence of anticholinesterasic effects, behavioral modifications were also observed. This set of data indicates that realistic levels of paracetamol may trigger the activation of the antioxidant defense system of freshwater crustaceans, causing changes in behavioral traits (increase in swimming time, but with a reduction in swimming distance) of unknown etiology that are likely to affect normal life traits of wild populations.

Standard and biochemical toxicological effects of zinc pyrithione in Daphnia magna and Daphnia longispina

Chemical toxicity in the environment may be the consequence of exposure of living organisms to multiple substances, with distinct putative effects. Among this mulytiplicity of chemicals that occur in the wild, pharmaceutical drugs and antifoulers are prone to exert toxic effects on non-target organisms. To characterize the toxicity elicited by a compound of this specific class, the present study used standard and biochemical-based tools to quantify the toxic response of the antifouler and antidandruff zinc pyrithione in Daphnia magna and Daphnia longispina. The analised parameters were immobility, reproduction, behavioral alteration (swimming patterns), anti-oxidant defense (catalase activity), metabolism (GSTs activities), and neurotoxicity (ChE activity) after exposure to sublethal concentrations of this drug. Exposure to zinc pyrithione has been shown to have neurotoxic and oxidative effects, with changes in swimming behavior. There were no changes in reproductive traits of exposed individuals, from both species. The obtained data demonstrate that ecologically relevant levels of zinc pyrithione can deleteriously alter critical parameters in two distinct freshwater microcrustacean species, although with distinct toxicity patterns and outcomes.

Sublethal effects on Simocephalus vetulus (Cladocera: Daphnidae) of pulse exposures of cypermethrin

Pyrethroids are among the most widely applied insecticides worldwide and cypermethrin is the pyrethroid most used in Argentina. Pesticides used in crops can reach adjacent watercourses through runoff and may lead to non-target fauna receiving toxic pulse exposures. The aim of this study was to determine the effects of cypermethrin pulse exposures on the widely distributed crustacean Simocephalus vetulus. The 48h-LC50 of cypermethrin for S. vetulus was determined at 0.18 ± 0.09 μg/L. To assess the effects of cypermethrin under environmentally realistic exposures, two experiments were performed. In the first one, specimens were exposed for 90 min to cypermethrin at 0.02 (T1), 0.2 (T2) and 1 μg/L (T3), transferred to clean water and monitored for 24 h as regards survival and feeding rates; specimens exposed to T2 and T3 concentrations showed significant lower feeding rates than those in the control group. In the second experiment, specimens were exposed for 90 min every 7 days and monitored over 25 days; S. vetulus showed lower cumulative fecundity and reproduction rates at all concentrations tested, and lower population growth at the highest concentration. All exposure concentrations lay within reported environmental concentrations and risk assessment indicated risk (RQ > 1), suggesting that sensitive species would be affected by such pulse exposures of cypermethrin. The present study thus suggests that ongoing agricultural practices affect the non-target invertebrates in streams adjacent to crops.

Examining the Differential Effects of a Universal SEL Curriculum on Student Functioning Through the Dual Continua Model of Mental Health

Social-emotional learning (SEL) curricula, such as Second Step, are increasingly being adopted and implemented as universal supports in schools in order to prevent social-emotional and behavioral problems and promote wellbeing and success. Notwithstanding the empirical support for SEL as a universal prevention strategy, a closer look at the literature indicates that students display differential responses to SEL based on their behavioral functioning at baseline; those students with the highest need benefit the most from SEL. The primary purpose of this study was to evaluate whether a widely-adopted SEL program produces significant effects for different theoretically-constructed groups of students who are representative of the full spectrum of students in a school. Using data from a large-scale randomized controlled trial evaluating Second Step, analyses examined the extent to which group membership according to the dual continua model of mental health differentially changed based on whether the student was in the intervention or control condition. Overall, results evidenced significant effects favoring the intervention condition across groups in line with our general hypotheses, although both conditions experienced transitions in membership. As expected, those in the intervention condition experienced greater transition between groups, which was indicative of either treatment or prevention effects. Implications, limitations, and future directions of the findings for SEL programming in schools are discussed.

Realistic pesticide exposure through water and food amplifies long-term effects in a Limnephilid caddisfly

Pesticides are increasingly recognized as relevant stressors in stream ecosystems. Stream biota is exposed to pesticides with low water solubility, e.g. pyrethroid insecticides, via water, habitat, and food. However, long-term effects of simultaneous exposure pathways are unknown. In this context, we conducted a microcosm experiment with the caddisfly Anabolia nervosa exposing the larvae to the pyrethroid insecticide esfenvalerate (EFV) at 0.1 and 1.0μgL^-1 via (i) water, (ii) food or a (iii) combination of water and food. Combined exposure through water and food significantly reduced emergence by 60% and significantly postponed emergence timing at the highest EFV level, whereas none of the single-phase exposures showed significant effects. Moreover, our study revealed that successfully emerged females from the highest biphasic treatment level were characterised by altered composition of storage lipids indicative of reduced energy reserves. Consequently, a realistic test scenario that represents simultaneous exposure of organisms and their food may reveal substantially increased long term effects of pyrethroids when compared with current ecological risk assessment applying only single phase exposure. We recommend that relevant concurrent exposure routes of pesticides should be considered in order to derive realistic regulatory acceptable concentrations of pesticides.

Circumpolar contaminant concentrations in polar bears (Ursus maritimus) and potential population-level effects

Polar bears (Ursus maritimus) currently receive much attention in the context of global climate change. However, there are other stressors that might threaten the viability of polar bear populations as well, such as exposure to anthropogenic pollutants. Lipophilic organic compounds bio-accumulate and bio-magnify in the food chain, leading to high concentrations at the level of top-predators. In Arctic wildlife, including the polar bear, various adverse health effects have been related to internal concentrations of commercially used anthropogenic chemicals like PCB and DDT. The extent to which these individual health effects are associated to population-level effects is, however, unknown. In this study we assembled data on adipose tissue concentrations of ∑PCB, ∑DDT, dieldrin and ∑PBDE in individual polar bears from peer-reviewed scientific literature. Data were available for 14 out of the 19 subpopulations. We found that internal concentrations of these contaminants exceed threshold values for adverse individual health effects in several subpopulations. In an exploratory regression analysis we identified a clear negative correlation between polar bear population density and sub-population specific contaminant concentrations in adipose tissue. The results suggest that adverse health effects of contaminants in individual polar bears may scale up to population-level consequences. Our study highlights the need to consider contaminant exposure along with other threats in polar bear population viability analyses.

Chromothripsis and epigenomics complete causality criteria for cannabis- and addiction-connected carcinogenicity, congenital toxicity and heritable genotoxicity

The recent demonstration that massive scale chromosomal shattering or pulverization can occur abruptly due to errors induced by interference with the microtubule machinery of the mitotic spindle followed by haphazard chromosomal annealing, together with sophisticated insights from epigenetics, provide profound mechanistic insights into some of the most perplexing classical observations of addiction medicine, including cancerogenesis, the younger and aggressive onset of addiction-related carcinogenesis, the heritability of addictive neurocircuitry and cancers, and foetal malformations. Tetrahydrocannabinol (THC) and other addictive agents have been shown to inhibit tubulin polymerization which perturbs the formation and function of the microtubules of the mitotic spindle. This disruption of the mitotic machinery perturbs proper chromosomal segregation during anaphase and causes micronucleus formation which is the primary locus and cause of the chromosomal pulverization of chromothripsis and downstream genotoxic events including oncogene induction and tumour suppressor silencing. Moreover the complementation of multiple positive cannabis-cancer epidemiological studies, and replicated dose-response relationships with established mechanisms fulfils causal criteria. This information is also consistent with data showing acceleration of the aging process by drugs of addiction including alcohol, tobacco, cannabis, stimulants and opioids. THC shows a non-linear sigmoidal dose-response relationship in multiple pertinent in vitro and preclinical genotoxicity assays, and in this respect is similar to the serious major human mutagen thalidomide. Rising community exposure, tissue storage of cannabinoids, and increasingly potent phytocannabinoid sources, suggests that the threshold mutagenic dose for cancerogenesis will increasingly be crossed beyond the developing world, and raise transgenerational transmission of teratogenicity as an increasing concern.

Chronic toxicity of the veterinary antibiotic florfenicol to Daphnia magna assessed at two temperatures

The hypothesis that temperature variation is able to modify the chronic toxicity of the antibiotic florfenicol (FLO) to Daphnia magna was tested in the present study. Twenty-one day laboratory bioassays were carried out at 20 and 25 °C. FLO concentrations and its potential decay during the assays were checked by spectrophotometry. At 20 °C, FLO significantly reduced the D. magna somatic growth (≥1.6 mg/L) and impaired its reproduction (EC₂₀=6.9 mg/L; EC₅₀=7.6 mg/L), with the population growth rate becoming negative at 12.6 mg/L. At 25 °C, the EC values were lower (1.7 and 1.9 mg/L, respectively) than at 20 °C, as well as the lowest exposure concentration causing a negative population growth rate (3.1 mg/L). These results clearly indicate that temperature raise from 20 to 25 °C was able to modify the FLO toxicity. Therefore, more studies on the combined effects of temperature changes and environmental contaminants are needed to improve the basis for ecological risk assessment, environmental and human safety.