Aquatic Model Research Articles

The efficiency of indigenous isolates Bacillus sp. RCS1 and Bacillus cereus RCS3 on growth performance, blood biochemical indices and resistance against Vibrio harveyi in cobia fish (Rachycentron canadum) juveniles

In this study, cobia (Rachycentron canadum) juveniles were utilised as an aquatic model to explore growth performance and immune indices after 70 days of feeding with supplementation of viable isolated microbes’ concentrations of 1 × 1010 and 1 × 1012 CFU/mL indigenous isolates Bacillus sp. RCS1 and Bacillus cereus strain RCS3, respectively. Regarding growth performance, fish provided with the indigenous isolates exhibited a significant (P < 0.05) enhancement. The hematological indices such as red blood cells, white blood cells, corpuscular haemoglobin concentration, mean corpuscular volume, haemoglobin, and Mean corpuscular haemoglobin were all increased (P < 0.05) in the juvenile cobia fed with indigenous isolates Bacillus sp. RCS1 and B. cereus RCS3 as a nutritional supplement. This study also significantly differed in serum analysis (albumin, globulin, lysozyme, total protein) between all the treatments with the Bacillus sp. RCS1 1 × 1010 proven to be the best. In the present study, the expression of myostatin and insulin-like growth factor 2 showed no significant change (P > 0.05) among the treatment and control groups tested; nonetheless, their mRNA expression exhibited variations in all trial groups. The present study showed significant differences (P < 0.05) among groups in the case of insulin-like growth factor 1, peroxisome proliferator-activated receptors. The improved antioxidant enzyme activities of catalase (CAT) and superoxide dismutase (SOD) digestive enzyme activities (amylase, trypsin, pepsin, lipase, and cellulose) may be linked to the enhanced resistance of fish against Vibrio harveyi infection. The enhanced activities of digestive enzymes in indigenous isolates treatments could be linked to the improved digestion and enhanced food absorption that ultimately helps enhance feed utilisation and growth performance. The results showed that indigenous isolates addition to a commercial diet, had the prospective to enhance cobia juveniles' growth and immune response regardless of their dosage.

A thermocatalytic perovskite-graphene oxide nanofiltration membrane for water depollution

A novel nanofiltration membrane, whose active layer consists of 98.6 wt% of a thermocatalytic perovskite with composition Sr0.85Ce0.15FeO3-δ (CSF), 1.0 wt% of graphene oxide (GO), and 0.4 wt% of a humic acid-like (HAL) crosslinker, was deposited over a commercial flat-sheet polyethersulfone support with good reproducibility by a simple 1-step coating procedure. The synergistic coupling of CSF and the crosslinked GO resulted in an improved catalytic activity for bisphenol A (BPA) abatement as a model pollutant. The thermocatalytic CSF/GO/HAL (GOT) membrane was tested in a nanofiltration crossflow apparatus with a model BPA solution and with a real urban wastewater treatment plant effluent. Its performances were compared with those of a HAL crosslinked GO (GOHAL) reference membrane. The GOT membrane presented high rejection towards BPA, antifouling properties, and stability under the filtration conditions. Moreover, when compared to the GOHAL reference, the thermocatalytic GOT membrane was able to reduce the concentration of BPA and the total organic carbon in the feed during filtration. Hence, the GOT membrane appears to have high potential in water treatment due to its multifunctional characteristics, which include molecular sieving, thermocatalytic oxidation of organic pollutants, and self-cleaning properties. Additionally, the membrane material showed no significant toxicity to the aquatic model organisms Raphidocelis subcapitata, Aliivibrio fischeri, and Daphnia magna at concentrations below 50 ppm.

Scanning electron microscopy for identification of local strain of Aspergillus Parasiticus and its larvicidal efficacy against Aedes Aegypti and non-target toxicity testing on fingerlings of Hypophthalmichthys Molitrix.

Scanning electron microscopy proved to be helpful in identification of Aspergillus parasiticus. A. parasiticus has a worldwide occurrence with high entomopathogenic efficacy against Aedes aegypti. However, assessment of pathogenic effects of entomopathogenic fungi on non-target organisms is required to evaluate its use as bio control agent. Aim of the present research is to study the parricidal activity of the local strain of A. parasiticus (MK371710) against A. aegypti and its toxicity assessment against aquatic model organism Hypophthalmichthys molitrix. A. parasiticus was isolated from the soil of Jallo Park, Lahore. The larvicidal effect of A. parasiticus was evaluated against fourth instar larvae of A. aegypti. Hundred percent of mortality of larvae was observed after exposure to 1 × 107 conidia/ml of fungal suspension after 72 h post treatment. The LC50 value of A. parsiticus in 24 h post treatment and 48 h post treatment was recorded as 1.0 × 107 conidia/ml 2.99 × 105 conidia/ml, respectively. However, an in-depth understanding safety to non-target organisms is necessary, if we are to properly control the action of these entomopathogenic fungi under natural conditions. For the toxicity assessment fingerlings of H. molitrix were exposed to conidial suspensions of A. parasiticus. Eye pop (64%), fin hemorrhage (33%), and scale infection (30%) were the major morphological effects observed during the study. Results reveal that although A. parasiticus is highly pathogenic to dengue vector but also have significant effects on organisms other than insects and its application as biological control agent requires safety considerations. HIGHLIGHTS: Assessment of pathogenic effects of entomopathogenic fungi on non-target organisms is required to evaluate its use as biocontrol agent. SEM was used to identify the microscopic view of Aspergillus parasiticus. Aim of the present research is to study the larvicidal activity of the local strain of A. parasiticus (MK371710) against Aedes aegypti and its toxicity assessment against aquatic model organism Hypophthalmichthys molitrix.

Ecotoxic effects of the vehicle solvent dimethyl sulfoxide on Raphidocelis subcapitata, Daphnia magna and Brachionus calyciflorus

ABSTRACT Dimethyl sulfoxide (DMSO) is widely used as a vehicle solvent in ecotoxicity bioassays.Despite its frequent use, it could be toxic for organisms at some concentrations. Hence, this study aims to investigate the effects of DMSO on the model organisms: microalgae Raphidocelis subcapitata, microcrustacean Daphnia magna, and rotifer Brachionus calyciflorus. DMSO was applied to the organisms in concentrations ranging from 0.031% to 4%. For R. subcapitata the lowest observed effect concentration (LOEC) after 72 h of exposure was 0.125% DMSO. The 50% effective concentration (EC50) was 2.138 ± 0.372%. In D. magna, significant differences in the mobility after 24 h or 48 h of exposure were observed for 1% DMSO being 1.712 ± 0.207% and 1.167 ± 0.220% DMSO the EC50 observed for 24 h and 48 h exposure, respectively. For B. calyciflorus, it was not possible to validate the tests performed, as there were insufficient animals alive in the control conditions at the end of the exposure period. Therefore, we recommended avoiding DMSO as a vehicle in assays using B. calyciflorus, and to use final DMSO concentrations in an experimental solution not exceeding 0.125% for R. subcapitata and 0.5% for D. magna. Finally, using a maximum of 0.01% DMSO is safe for the organisms tested. The effects of the vehicle solvent dimethyl sulfoxide (DMSO) were investigated in three aquatic model organisms, the microalgae Raphidocelis subcapitata, the microcrustacean Daphnia magna and the rotifer Brachionus calyciflorus. As a result, negative effects on growth rate for the algae population, immobilisation of daphnids and inhibition of rotifer reproduction was observed obtaining EC50 close to 1% of DMSO for all these cases.

An Integrated Modelling Study on the Effects of Weir Operation Scenarios on Aquatic Habitat Changes in the Yeongsan River

The Seungchon and Juksan Weirs were constructed in 2012 through four major river projects to control floods and secure water in the Yeongsan River. However, anthropogenic changes in the environment can lead to loss of biodiversity and longitudinal connectivity and the deterioration of ecosystem health. The objective of this study is to evaluate the effects of physical and chemical changes in the Yeongsan River on aquatic habitats through an integrated (water quality–aquatic habitat) model (i.e., Delft3D and HABITAT). The target species used to simulate habitat suitability included Squalidus chankaensis tsuchigae (an endemic fish), Cyprinus carpio, and Micropterus salmoides (an invasive species of fish). Based on the results, maintaining the lowest water level in one of the two weirs was predicted to improve the habitat of the target species. In particular, the habitat area was greatly improved, especially when the Juksan Weir was completely opened. Furthermore, resistance to environmental changes due to habitat area changes indicates that invasive species adapt more to environmental changes than endemic species. This study suggests that physical and chemical changes in the environment can predict the impact on the health of the aquatic ecosystems, which will be useful in establishing an integrated water management plan. These results can be used as basic data for supporting water management policy, to apply an aquatic ecology prediction model suitable for the Yeongsan River system, and to present a management plan for improving the health of an aquatic ecosystem.

Hypoxia regulates cytokines expression and neutrophils migration by ERK signaling in zebrafish

Normal dissolved oxygen in water is essential for maintaining the physiological functions of fish, but environmental pollution, such as eutrophication can lead to a decrease in oxygen content in water. How this reduction of dissolved oxygen in water affects the immune functions of fish and the potential regulatory mechanisms have not been thoroughly elucidated. In this study, we made full use of the aquatic model animal zebrafish to explore this question. In a model of LPS-induced inflammation, we found that hypoxia induced by infusing nitrogen into water increased the expression of pro-inflammatory cytokines, such as il-1β, il-6, and il-8. In vivo imaging also showed that hypoxia significantly increased neutrophil migration to the site of caudal fin injury in the transgenic line. Subsequently, we found that the phosphorylation level of ERK protein was significantly activated upon hypoxia and proved the roles of ERK signaling in the expression of pro-inflammatory cytokines and neutrophil migration in zebrafish. This study indicated that reduced water oxygen significantly increases the inflammatory response of the zebrafish.

MALDI mass spectrometry imaging workflow for the aquatic model organisms Danio rerio and Daphnia magna

Lipids play various essential roles in the physiology of animals. They are also highly dependent on cellular metabolism or status. It is therefore crucial to understand to which extent animals can stabilize their lipid composition in the presence of external stressors, such as chemicals that are released into the environment. We developed a MALDI MS imaging workflow for two important aquatic model organisms, the zebrafish (Danio rerio) and water flea (Daphnia magna). Owing to the heterogeneous structure of these organisms, developing a suitable sample preparation workflow is a highly non-trivial but crucial part of this work and needs to be established first. Relevant parameters and practical considerations in order to preserve tissue structure and composition in tissue sections are discussed for each application. All measurements were based on high mass accuracy enabling reliable identification of imaged compounds. In zebrafish we demonstrate that a detailed mapping between histology and simultaneously determined lipid composition is possible at various scales, from extended structures such as the brain or gills down to subcellular structures such as a single axon in the central nervous system. For D. magna we present for the first time a MALDI MSI workflow, that demonstrably maintains tissue integrity during cryosectioning of non-preserved samples, and allows the mapping of lipids in the entire body and the brood chamber inside the carapace. In conclusion, the lipid signatures that we were able to detect with our method provide an ideal basis to analyze changes caused by pollutants in two key aquatic model organisms.

Comparative Toxicity Assessment of Eco-Friendly Synthesized Superparamagnetic Iron Oxide Nanoparticles (SPIONs) in Plants and Aquatic Model Organisms

This study aimed to evaluate the toxicity of superparamagnetic iron oxide nanoparticles (SPIONs) synthesized by biogenic (BS) and chemical (CH) routes. The nanoparticles were characterized by X-ray diffraction (XRD), X-ray spectroscopy (XPS), atomic force microscopy (AFM), vibrating-sample magnetometry (VSM-SQUID), Fourier-transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). The toxicity of SPIONs was evaluated using Artemia salina as model aquatic organisms and Raphanus sativus and Lactuca sativa as model plants to evaluate their phytotoxicity. The results obtained from XRD, XPS, and AFM confirmed the formation of spherical nanoparticles of 41.9 ± 1.00 nm (BS route) and 19.8 ± 0.47 nm (CH route). VSM-SQUID demonstrated the superparamagnetic behavior of both nanoparticles, and FT-IR provided evidence of the differences in the surface of SPIONs, suggesting the presence of phenolic compounds on the surface of BS-SPIONs. For the assays with Artemia salina, the results demonstrated (i) nonsignificant differences of BS-SPIONs in mortality rates, and (ii) significant toxicity (p &lt; 0.05) was observed for CH-SPIONs at 300 and 400 mg L−1. The Raphanus sativa plant assay tests showed (i) BS-SPIONs and CH-SPIONs improved the root elongation of seedlings. However, BS-SPIONs demonstrated significant activity on root seedling elongation (p &lt; 0.05) in the range of 300 mg L−1 to 600 mg L−1. To the best of our knowledge, this is the first report to compare the toxicity of chemically and biogenically synthesized SPIONs. In conclusion, although BS-SPIONs and CH-SPIONs present similar structures, their characteristics of magnetic saturation and surface structure are nonidentical, providing differences in their biological activity.

A Brief Insight on the In vitro Growth of Lesser Duckweed – Lemna minor L. under varying lightconditions

Exhaustive investigation in plant physiology, plant biochemistry and ecological toxicity especially in aquatic environment requires a promising aquatic model plant for which L.minor L. is best suited. It is considered to be a rich source of proteins and can replace traditional source of proteins both for food and feed. Its optimal growth and biomass accumulation under laboratory condition requires balance among the different macro and micro elements of the composition of the culture medium along with optimal spectral distribution. The focus of the present review is to study the in vitro growth of L.minor L. under different culture parameters maintained with normal and modulated physico-chemical conditions including varying photoperiod regime along with different spectral distribution.

Synthetic Progestins in Waste and Surface Waters: Concentrations, Impacts and Ecological Risk.

Synthetic progestins (PGs) are a large family of hormones used in continuously growing amounts in human and animal contraception and medicinal therapies. Because wastewater treatment plants (WWTPs) are unable to eradicate PGs after excretion, they are discharged into aquatic systems, where they can also be regenerated from conjugated PG metabolites. This review summarises the concentrations of 12 PGs in waters from 2015 to 2021. The selected PGs were considered of particular interest due to their wide use, activity, and hormonal derivation (from testosterone, progesterone, and spirolactone). We concluded that PGs had been analysed in WWTPs influents and effluents and, to a lesser extent, in other matrices, including surface waters, where their concentrations range from ng/L to a few µg/L. Because of their high affinity for cell hormone receptors, PGs are endocrine disruptor compounds that may alter the reproductive fitness and development of biota. This review focused on their biological effects in fish, which are the most used aquatic model organisms to qualify the impacts of PGs, highlighting the risks that environmental concentrations pose to their health, fecundity, and fertility. It is concluded that PGs research should be expanded because of the still limited data on their environmental concentrations and effects.

Reductive Transformation of Hexavalent Chromium in Ice Decreases Chromium Toxicity in Aquatic Animals.

In this study, the toxicity of hexavalent chromium [Cr(VI)] reduced by citric acid in ice was measured using representative aquatic model invertebrates (i.e., rotifer, water flea, amphipod, and polychaete) and a vertebrate (zebrafish) by analyzing short- and/or long-term endpoints that are frequently applied to each animal. Cr(VI) reduction in the presence of citric acid was markedly enhanced in the ice phase compared to that in an aqueous solution through the freeze concentration effect. The highly concentrated Cr(VI) and citric acid in ice grain boundaries were also confirmed using in situ cryogenic confocal Raman spectroscopy. Overall, exposure to Cr(VI) resulted in higher acute and/or chronic effects on aquatic animals, such as drastic mortality, growth inhibition, and decrease in offspring number, whereas the animals were increasingly tolerant to Cr(VI) that was reduced in the ice phase. Sublethal concentrations of Cr(VI) significantly decreased the antioxidant capacity in the aquatic animals. However, when the same concentrations of Cr(VI) were reduced in ice, these treatments showed no modulation or increase in the antioxidant defense system. Taken together, our results suggest that Cr(VI) reduction into Cr(III) was successfully achieved in ice and that this methodology can decrease the actual toxicity of Cr(VI) in aquatic animals.

Sensitivity of aquatic habitat modeling to hydrodynamic calibration

Fish habitats and reproduction can be significantly altered downstream of hydroelectric power plants operated by hydropeaking and resulting in rapid and frequent changes in river hydrodynamic conditions. To mitigate the impacts, it is necessary to maintain the habitat quality through operational measures. The microhabitat method, coupling 1 D or 2 D hydraulic simulations to biological models, is a useful tool to assess the evolution of hydromorphological parameters and fish habitats and define these mitigation measures. Calibration of the hydraulic model must be carried out carefully because the model must accurately reproduce hydraulic conditions from low to high flows. The objective is therefore to evaluate the sensitivity of the habitat value as a function of the type of calibration and the friction law for shallow habitats. The analysis is performed by estimating the uncertainty in fish habitat values resulting from Strickler’s law or Nikuradse’s law. The study is carried out on a river in the French Pyrenees based on the modeling of 2 stations with different cross-sectional shapes, one with progressive overflow and the other without these phenomena. Thanks to field measurements at low and high flowrates, the calibration process showed that the friction coefficient can be multiplied by 2. Two dimensionnal simulations give similar results to those obtained with 1 D when the flow remains unidirectional but differ for areas with high overflows. Calibration and models can lead to different conclusions regarding the estimation of habitat modifications due to hydropeaking operation and the definition of base flow and maximum turbine discharge.

Remote Sensing to Characterize River Floodplain Structure and Function

Advancing understanding of the complexities and expansive spatial scales of river ecology can be enhanced through the application of remote sensing. We obtained satellite (Quickbird) and airborne (LIDAR, hyperspectral, multispectral, and thermal) imagery data of an alluvial gravel-bed river floodplain in western Montana to quantify both riparian and aquatic habitats and processes. LIDAR data provided a detailed bare earth DEM and vegetation canopy DEM. We classified river hydraulics and aquatic habitats using a combination of the satellite multispectral, airborne hyperspectral, and LIDAR data coupled with spatially-explicit acoustic Doppler velocity profile data of water depth and velocity. Velocity, depth, and Froude classifications were aggregated into similar hydraulic zones of river habitat classes. Thermal imagery data were coupled with field measurements of temperature and radon gas tracer to identify patterns of water exchange between the alluvial aquifer and the surface. We found a high complexity of aquatic surface temperatures and radon tracer linked to groundwater discharge from the alluvial aquifer. Airborne hyperspectral data were used to identify “hot spots” of periphyton production, which coincided with the complex nature of groundwater–surface water exchange. Airborne hyperspectral data provided differentiation of vegetation patches by dominant species. When the hyperspectral data were coupled to LIDAR first return metrics, we were able to determine vegetation canopy height and relative vegetation patch age classes. The integration of these various remote sensing sources allowed us to characterize the distribution and abundance of floodplain aquatic and riparian species and model processes of change through space and time.

Removal of Fecal Indicator Bacteria by River Networks

Fecal contamination is a significant source of water quality impairment globally. Aquatic ecosystems can provide an important ecosystem service of fecal contamination removal. Understanding the processes that regulate the removal of fecal contamination among river networks across flow conditions is critical. We applied a river network model, the Framework for Aquatic Modeling in the Earth System (FrAMES-Ecoli), to quantify removal of fecal indicator bacteria by river networks across flow conditions during summers in a series of New England watersheds of different characteristics. FrAMES-Ecoli simulates sources, transport, and riverine removal of Escherichia coli (E. coli). Aquatic E. coli removal was simulated in both the water column and the hyporheic zone, and is a function of hydraulic conditions, flow exchange rates with the hyporheic zone, and die-off in each compartment. We found that, at the river network scale during summers, removal by river networks can be high (19–99%) with variability controlled by hydrologic conditions, watershed size, and distribution of sources in the watershed. Hydrology controls much of the variability, with 68–99% of network scale inputs removed under base flow conditions and 19–85% removed during storm events. Removal by the water column alone could not explain the observed pattern in E. coli, suggesting that processes such as hyporheic removal must be considered. These results suggest that river network removal of fecal indicator bacteria should be taken into consideration in managing fecal contamination at critical downstream receiving waters.

Diethylhexyl phthalate as a current problem of hygienic safety of packaging and packaged drinking water

Introduction. The chemical safety of packaged drinking water is influenced by many factors, including the quality of packaging materials. The chemical components included in the packaging can migrate into drinking water and have a negative impact on human health. The most common types of packaging for drinking water are polyethylene terephthalate (PET, PET) and polycarbonate (PC) bottles. In the production of polymers, to soften and increase the flexibility of the finished product, special substances are added to the material - plasticisers, including dialkyl or alkyl aryl esters of orthophthalic acid (phthalates), among which di (2-Ethylhexyl) phthalate (DEHP), which has toxic properties. The purpose of this study is to analyse various samples of plastic containers in contact with drinking water for the presence of DEHP in polymers and to study the emission of DEHP from polymer packaging into a model environment. Materials and methods. Research has been carried out on 11 samples of containers for drinking water of domestic production, of which nine samples were represented by PET bottles of various sizes and two samples of containers from PC with a volume of 19.0 litres. There was determined the content of DEHP in the container material and the level of migration of DEHP into the aqueous model environment. Sanitary and hygienic studies were carried out based on the Chemical Analytical Center “Arbitrage” of the DI. Mendeleev All-Russian Scientific Research Institute using gas chromatography with mass spectrometric detection (GC-MS). GSO 11366-2019 for the composition of a solution of orthophthalic acid esters in methanol was used as a standard sample for the calibration characteristics; a deuterated analogue of the analyte, DEHP-D4, was chosen as an internal standard. Results. In all studied samples of packaging materials, the residual content of DEHP was in the range of 1.7-4.2 mg/kg of polymer; the levels of DEHP migration into aquatic model media were determined at T = 20 °C and T = 40 °C in the range of (8.6-71.0) μg/dm3. Conclusion. One of the sources of contamination of packaged drinking water with DEHP is PET and PC containers. The results obtained indicate the need to include DEHP in the list of monitored sanitary and hygienic safety indicators in the technical regulations of the EAEU TR 044/2017 and TR CU 005/2011 and to consider the issue of restrictions on its use in the production of food packaging. Limitations of the study. As part of this work, samples of bottles from six domestic container manufacturers were analysed. To study the migration of the target component, a model medium was used - distilled water, which does not imitate the mineral composition of drinking water and has certain pH and electrical conductivity values. Studies of the level of DEHP migration were carried out at an ambient temperature of 20 °C and 40 °C and an exposure time of 30 days. The measurement range of DEHP in polymers and the model medium in this study was (0.1-5) µg/sample. The expanded uncertainty of the results of measurements of the DEHP content in the entire measurement range did not exceed 20%.

Impact of test chamber design on spontaneous behavioral responses of model crustacean zooplankton Artemia franciscana.

The use of small aquatic model organisms to investigate the behavioral effects of chemical exposure is becoming an integral component of aquatic ecotoxicology research and neuroactive drug discovery. Despite the increasing use of invertebrates for behavioral phenotyping in toxicological studies and chemical risk assessments, little is known regarding the potential for environmental factors-such as geometry, size, opacity and depth of test chambers-to modulate common behavioral responses. In this work, we demonstrate that test chamber geometry, size, opacity and depth can affect spontaneous, unstimulated behavioral responses of euryhaline crustacean Artemia franciscana first instar larval stages. We found that in the absence of any obvious directional cues, A. franciscana exhibited a strong innate wall preference behavior. Using different test chamber sizes and geometries, we found both increased wall preference and lowered overall distance traveled by the test shrimp in a smaller chamber with sharper-angled vertices. It was also determined through quantifiable changes in the chambers' color that the A. franciscana early larval stages can perceive, differentiate and react to differences in color or perhaps rather to light transmittance of the test chambers. The interaction between innate edge preference and positive phototaxis could be consistently altered with a novel photic stimulus system. We also observed a strong initial preference for depth in A. franciscana first instar larval stages, which diminished through the acclimatization. We postulate that the impact of test chamber designs on neurobehavioral baseline responses warrants further investigation, in particular considering the increased interest in behavioral eco-neurotoxicology applications.

Cylindrospermopsin impairs zebrafish (Danio rerio) embryo development

Cyanotoxins are among common contaminants that can impair human, animal, and environmental health. Cylindrospermopsin (CYN) is an abundant form of cyanotoxins elevated following algal bloom in the water worldwide. Previous studies have described CYN effects on several organs in mammals. However, little is known about its toxicity mechanisms in other vertebrates. This study aims to characterize the developmental effects of CYN using zebrafish larvae as an aquatic model organism. A wide range of CYN concentrations (0–2000 μg/L) was tested using a morphometric approach for survival, hatching, various growth and developmental abnormalities. We also investigated the expression of genes related to oxidative stress, osmoregulation, and thyroid function. Exposure to CYN resulted in decreased growth, increased developmental abnormalities such as pericardial and yolk sac edema as well as swim bladder absence. In addition, CYN increased tr1a, and decreased dio1 and dio3 transcript levels which are involved in thyroid-mediated function. It also increased transcript levels related to oxidative stress, including hsp70, ahr1a, cyp1a, gpx and cat. Lastly, CYN exposure increased aqp3a and decreased dab2, which are involved in osmoregulation with a threshold of 10 μg/L. The present study demonstrates multiple effects of exposure to environmentally relevant CYN concentrations in zebrafish embryos.

Determination of histopathological effects and myoglobin, periostin gene-protein expression levels in Danio rerio muscle tissue after acaricide yoksorrun-5EC (hexythiazox) application

Although pesticides are essential agrochemicals to annihilate harmful organisms in agriculture, their uncontrolled use has become an important threat to environmental health. Exposure to pesticides can affect many biological systems including immune system, endocrine system, and nervous system. However, the potential side effects of pesticides to skeletal muscle system remain unclear. Present study has focused on the evaluation of this issue by using an acaricide, yoksorrun-5EC (hexythiazox), in an aquatic model organism, Danio rerio. The histological analyses revealed that increased concentrations of the acaricide cause degradation of skeletal muscle along with increased necrosis and atrophy in myocytes, intercellular edema, and increased infiltrations between perimysium sheaths of muscle fibers. The effects of acaricide on myoglobin and periostin, which are associated with oxygen transport and muscle regeneration, respectively, were investigated at the gene and protein levels. RT-PCR results suggested that high concentration yoksorrun-5EC (hexythiazox) can induce myoglobin and periostin genes. Similar results were also obtained in the protein levels of these genes by western blotting analysis. These results suggested that yoksorrun-5EC (hexythiazox)-dependent disruption of skeletal muscle architecture is closely associated with the expression levels of myoglobin and periostin genes in Danio rerio model.

Authors\u2019 response on Perkins et al. (2021) \u201cDead in the water: comment on \u201cDevelopment of an aquatic exposure assessment model for imidacloprid in sewage treatment plant discharges arising from use of veterinary medicinal products\u201d

In 2020, Anthe et al. published a newly developed model to predict imidacloprid surface water concentrations stemming from sewage treatment plant (STP) effluent as a consequence of the use of veterinary medicinal products containing imidacloprid in the UK (Anthe in Environ Sci Eur (2020) 32:147, https://doi.org/10.1186/s12302-020–00424-4). The modelled data indicate that these veterinary medicinal products make only a very small contribution to the levels of Imidacloprid observed in the UK water monitoring programme.The commentary by Perkins et al. (Perkins in Environ Sci Eur (2021) 33:88, https://doi.org/10.1186/s12302-021-00533-8) questioned the validity and conclusions of the modelling approach. We believe the modelling approach, which considered what we anticipated to be, the major exposure pathways, gives a realistic picture of the chronic emission via STPs to UK rivers.

Shedding light on the impacts of gestational exposure to polystyrene nanoplastics on the reproductive performance of Poecilia reticulata female and on the biochemical response of embryos

Although the toxicity of nanoplastics (NPs) has already been reported in experimental aquatic models, their possible effects on the reproductive performance of viviparous freshwater fish and their consequences for embryos, so far, are unknown. Thus, we aimed to evaluate whether the gestational exposure of Poecilia reticulata to polystyrene NPs (PS NPs) impacts the reproductive performance of females, induces teratogenic effects and/or predictive alterations of redox unbalance and cholinesterasic effect. Our results demonstrate that gestational exposure of P. reticulata females (for 30 days) to PS NPs (50 µg/L) affected reproductive aspects of the animals, inferred by the lower percentage of pregnancy and reduced offspring quantity. Although we did not observe teratogenic effect, we observed that the accumulation of PS NPs in embryos was significantly correlated with a redox unbalance, without, however, having a cholinesterasic effect (via evaluation of AChE and BChE activity) in embryos. Thus, by evidencing the accumulation of PS NPs in embryos of P. reticulata females exposed to the pollutant during the gestational period, we confirm not only the plausibility of the maternal transfer of these nanomaterials, but also their consequent physiological impacts on the offspring, which has not yet been demonstrated in live-bearing freshwater fish.