Tail Deformities Research Articles

Flavor compound geraniol induces inhibited nutrient utilization and developmental toxicity on embryonic–larval zebrafish

AbstractFlavors are widely utilized in the food and oral pharmaceutical industry, particularly in products for children, to enhance palatability and promote ingestion willingness. The complex compositions of flavors potentially induce severer toxicity especially in children. In this study, zebrafish embryos are applied for toxicity screening of flavor and its compounds by immersing in flavor solutions followed by the assessment of morphology of zebrafish larvae. Geraniol is identified as the prominent toxic compound and is considered highly toxic to zebrafish embryo. In further toxicology study, geraniol demonstrates the concentration‐dependent developmental toxicity as the obvious reduction of body and eye lengths, as well as the increased prevalence of tail deformities, pericardial edema, and spine deformation. Zebrafish larvae treated with geraniol exhibit reduction in liver area and exocrine pancreas length, increase in yolk sac area, as well as elevation of triglycerides and total cholesterol, which indicate the inhibited nutrient utilization. Transcriptome analysis reveals that under geraniol treatment, 248 differentially expressed genes (DEGs) are downregulated, whereas 23 DEGs are upregulated, and 110 DEGs are related to metabolic process. Biological processes of lipid metabolism, carbohydrate metabolism, protein hydrolysis, and transmembrane transport, including their involved functional genes, are all downregulated. These findings reveal the developmental toxicity of geraniol by affecting the nutrient utilization‐related organs development and biological processes. This study establishes an efficient screening model for identifying toxic flavor compounds during developing stages, thereby elucidating the potential safety risks of geraniol exposure in zebrafish and providing a comprehensive understanding of its potential toxicity mechanism.

Developmental toxicity in zebrafish embryos exposed to single, binary, and tertiary mixtures of Cd, Pb, and As

The present study was carried out to investigate developmental toxicity to zebrafish upon exposure singly to cadmium chloride monohydrate (25 µg/L), or lead acetate (40 µg/L), or arsenic trioxide (40 µg/L), and their toxicological interactions upon exposure to combinations of Cd + Pb, Pb + As, Cd + As, and Cd + Pb + As for 120 h post fertilization. Cumulative mortality at 72, 96, and 120 h were significantly higher in all toxicity groups. Cd, Pb, and Pb + As exposure caused 92–100% mortality at 96 h of the exposure. The highest reduction of hatching rate was observed in the Pb + As group followed by the Cd + Pb group. The heart rate was significantly decreased in Cd, As, Cd + Pb, and Cd + Pb + As groups as compared to the control group. Body length, eye size, and cranium size were significantly affected in most of the toxicity groups. The exposure of Cd and Pb increased yolk sac size in the larvae as compared to other treatments. The Pb and Cd exposure group exhibited more tail and spinal deformities. The Cd + Pb exposure group exhibited pericardial and yolk sac edema in the larvae. There may be a possibility of toxicological interaction among Cd, Pb, and As, and may cause developmental defects in fish at the early life stages.

Expression pattern and functional analysis of kinesin-14 KIFC1 in spermatogenesis of Macaca mulatta

C-terminal kinesin motor KIFC1 is increasingly concerned with an essential role in germ cell development. During the spermatogenesis of mice, rats, and crustaceans, KIFC1 functions in regulating meiotic chromosome separation, acrosome vesicle transportation, and nuclear morphology maintenance. The expression pattern of KIFC1 is conservatively concentrated at the acrosome and nucleus of haploid sperm cells. However, whether KIFC1 has similar functions in non-human primates remains unknown. In this study, we constructed the testis-specific cDNA library and cloned different transcripts of KIFC1 based on the genomic sequence. New variants of KIFC1 were identified, and showed different functional domains from the predicted isoforms. The spatio-temporal expression of KIFC1 proteins in seminiferous tubules of rhesus monkeys showed an obvious nuclear localization, specifically expressed in the spermatocytes and early haploid spermatids. The transcripts of KIFC1 also exhibited considerable expression in the nucleus of rhesus LLC-MK2 cells. Besides, we demonstrated that KIFC1 located at the acrosome and microtubule flagella of the mature sperm, and KIFC1 inhibition resulted in sperm tail deformation as well as increased the instability of head-to-tail connection. In summary, this study filled a gap in the reproductive research of the KIFC1 gene in non-human primates.

Assessment of toxicity of pyriproxyfen, Bacillus thuringiensis, and malathion and their mixtures used for mosquito control on embryo-larval development and behavior of zebrafish.

Pyriproxyfen (PPF), Bacillus thuringiensis israelensis (BTI), and malathion (MLT) are widely used worldwide to control the population of mosquitos that transmit arboviruses. The current work aimed to evaluate the toxicity of these single pesticides and their binary mixtures of PPF + BTI, PPF + MLT, and MLT + BTI on the embryo-larval stage of zebrafish (Danio rerio) as an animal model. Epiboly, mortality, apical endpoints, affected animals, heart rate, morphometric, thigmotaxis, touch sensitivity, and optomotor response tests were evaluated. PPF and MLT and all mixtures reduced the epiboly percentage. Mortality increased significantly in all exposed groups, except BTI, with MLT being the most toxic. The observed apical endpoints were pericardial and yolk sac edemas, and tail and spine deformation. Exposure to MLT showed a higher percentage of affected animals. A reduction in heart rate was also observed in MLT- and PPF + MLT-exposed groups. The PPF + MLT mixture decreased head measurements. Behavioral alterations were observed, with a decrease in thigmotaxis and touch sensitivity responses in PPF + MLT and MLT + BTI groups. Finally, optomotor responses were affected in all groups. The above data obtained suggest that the MLT + PFF mixture has the greatest toxicity effects. This mixture affected embryo-larval development and behavior and is close to the reality in several cities that use both pesticides for mosquito control rather than single pesticides, leading to a reevaluation of the strategy for mosquito control.

Captopril's influence on Danio rerio embryonic development: Unveiling significant toxic outcomes at environmentally relevant concentrations

Anticipating a global increase in cardiovascular diseases, there is an expected surge in the use of angiotensin-converting enzyme inhibitors, notably captopril (CAP). This heightened usage raises significant environmental apprehensions, mainly due to limited knowledge regarding CAP's toxic effects on aquatic species. In response to these concerns, the current study aimed to tackle this knowledge gap by evaluating the potential influence of nominal concentrations of CAP (0.2–2000 μg/L) on the embryonic development of Danio rerio. The findings revealed that CAP at all concentrations, even at concentrations considered environmentally significant (0.2 and 2 μg/L), induced various malformations in the embryos, ultimately leading to their mortality. Main malformations included pericardial edema, craniofacial malformation, scoliosis, tail deformation, and yolk sac deformation. In addition, CAP significantly altered the antioxidant activity of superoxide dismutase and catalase across all concentrations. Simultaneously, it elevated lipid peroxidation levels, hydroperoxides, and carbonylic proteins in the embryos, eliciting a substantial oxidative stress response. Likewise, CAP, at all concentrations, exerted significant modulatory effects on the expression of genes associated with apoptosis (bax, bcl2, p53, and casp3), organogenesis (tbx2a, tbx2b, and irx3b), and ion exchange (slc12a1 and kcnj1) in Danio rerio embryos. Both augmentation and reduction in the expression levels of these genes characterized this modulation. The Pearson correlation analysis indicated a close association between oxidative damage biomarkers and the expression patterns of all examined genes with the elevated incidence of malformations and mortality in the embryos. In summary, it can be deduced that CAP poses a threat to aquatic species. Nevertheless, further research is imperative to enhance our understanding of the environmental implications of this pharmaceutical compound.

Multilevel assessment of carbamazepine effects: An integrative approach using zebrafish early-life stages

Carbamazepine (CBZ) is the most commonly used drug in epilepsy treatment, and its metabolites are commonly detected among persistent pharmaceuticals in the aquatic environment. This study aimed to investigate CBZ effects on early-life-stage zebrafish (Danio rerio) (from 2 to 168 hpf) by employing of an integrative approach linking endpoints from molecular to individual level: (i) development; (ii) locomotor activity; (iii) biochemical markers (lactate dehydrogenase, glutathione-S-transferase, acetylcholinesterase and catalase) and (iv) transcriptome analysis using microarray. A 168 h - LC50 of 73.4 mg L−1 and a 72 h - EC50 of 66.8 mg L−1 for hatching were calculated while developmental effects (oedemas and tail deformities) were observed at CBZ concentrations above 37.3 mg L−1. At the biochemical level, AChE activity proved to be the most sensitive parameter, as evidenced by its decrease across all concentrations tested (∼25% maximum reduction, LOEC (lowest observed effect concentration) < 0.6 μg L−1). Locomotor behaviour seemed to be depressed by CBZ although this effect was only evident at the highest concentration tested (50 mg L−1). Molecular analysis revealed a dose-dependent effect of CBZ on gene expression. Although only 25 genes were deregulated in organisms exposed to CBZ when compared to controls, both 0.6 and 2812 μg L−1 treatments impaired gene expression related to development (e.g. crygmxl1, org, klf2a, otos, stx16 and tob2) and the nervous system (e.g. Rtn3, Gdf10, Rtn3), while activated genes were associated with behavioural response (e.g. prlbr and taar). Altogether, our results indicate that environmentally relevant CBZ concentrations might affect biochemical and genetic traits of fish. Thus, the environmental risk of CBZ cannot be neglected, especially in a realistic scenario of constant input of domestic effluents into aquatic systems.

Detection of heavy metals from Harpadon nehereus, Channa punctata and Pampus chinensis dried fishes and toxicity study of Channa punctata on embryonic zebrafish

ObjectivesGlobally, heavy metal pollution is one of the major serious environmental issues. The present investigations were carried out to determine the heavy metals concentrations from three dried fish along with the toxicity effects of Channa punctata dried fish on embryonic development of zebrafish. MethodsThe concentrations of heavy metals, Nickel (Ni), Chromium (Cr), Cadmium (Cd), Arsenic (As), and Lead (Pb) were detected from Harpadon nehereus, C. punctata and Pampus chinensis dried fish’s samples by Atomic Absorption Spectrophotometry (AAS) method. ResultsThe highest concentrations of As and Pb were 3.65 ± 0.08 and 3.29 ± 0.07 ppm, found in C. punctata followed by 3.11 ± 0.05 and 3.26 ± 0.07 ppm, in H. nehereus, respectively. Meanwhile, no significant levels of Ni, Cr and Cd were found in all the three tested dried fishes, compared with standard references. The treatments of 50 µg/ml and 100 µg/ml C. punctata dried fish solution on zebrafish embryos showed significant toxicity and abnormalities of unequal blastomeric curve, yolk sac edema, pericardial edema, spinal curvature and tail deformation at 24, 33, 48, 72 and 96 h post fertilization (hpf). ConclusionsThe present investigation revealed that the tested dried fishes contain heavy metals and C. punctata is highly toxic for zebrafish embryos.

Unveiling the molecular mechanisms and developmental consequences of mercury (Hg) toxicity in zebrafish embryo-larvae: A comprehensive approach

Mercury (Hg) is a global contaminant affecting aquatic ecosystems' health. Chronic exposure to Hg has shown that the normal development of zebrafish embryo-larvae is affected. However, the molecular mechanisms behind the toxicity of Hg on fish embryonic development are still poorly understood. This work aimed to investigate the effects of Hg exposure on zebrafish embryo-larvae using a combined approach at individual (mortality, embryo development and locomotor behavior) and biochemical (neurotoxicity and oxidative stress enzymatic activities and protein phosphatase expression) levels. The Fish Embryo Toxicity assay followed the Organization for Economic Cooperation and Development Guideline 236 and used a concentration range between 13 and 401 μg Hg/L. Lethal and developmental endpoints were examined at 24, 48, 72 and 96 hpf. Biochemical markers, including Acetylcholinesterase (AChE), Catalase (CAT), Glutathione Reductase (GR), and Glutathione-S-Transferase (GST) activities and, for the first time, the expression of the protein phosphatase 1 gamma (PP1γ) was assessed after 24, 48, 72 and 96 h of exposure to 10 and 100 μg Hg/L. The behavioral effects of a sublethal range of Hg (from 0.8 to 13 μg Hg/L) were assessed using an automated video tracking system at 120 hpf. Several developmental abnormalities on zebrafish embryos and larvae, including pericardial edema, spin and tail deformities and reduced rate of consumption of the yolk sac, were found after exposure to Hg (LC50 at 96 hpf of 139 μg Hg/L) with EC50 values for total malformations ranging from 22 to 264 μg Hg/L. After 96 hpf, no significant effects were observed in the CAT and GR activities. However, an increase in the GST activity in a concentration and time-dependent manner was found, denoting possible stress-related adaptation of zebrafish embryos to deleterious effects of Hg exposure. The AchE activity showed a response pattern in line with the behavioral responses. At the lowest concentration tested, no significant effects were found for the AChE activity, whereas a decrease in AChE activity was observed at 100 μg Hg/L, suggesting that exposure to Hg induced neurotoxic effects in zebrafish embryos which in turn may explain the lack of equilibrium found in this study (EC50 at 96 hpf of 83 μg Hg/L). Moreover, a decrease in the PP1γ expression was found after 96 h of exposure to 10 and 100 μg Hg/L. Thus, we suggest that Hg may be an inhibitor of PP1γ in zebrafish embryos-larvae and thus, along with the alterations in the enzymatic activity of GST, explain some of the developmental malformations observed, as well as the lack of equilibrium. Hence, in this study, we propose the use of PP1 expression, in combination with apical and biochemical endpoints, as a precursor for assessing Hg's toxic mechanism on embryonic development.

Cytotoxicity Effects of Azithromycin and Curative of Garlic on Sperm Mortality and Testicular Tissue of Albino Male Rats

The current study aimed to identify the adverse effects of azithromycin drug and the protective role of garlic in cytotoxicity tests that included sperm deformation and histological changes in testes tissue of male albino rats. Twenty-four mature male rat animals (Rattus norvegicus) were used in the present study, their age was (2.5 – 3) months, and their weight ranged from 148 to 280 gm they were divided into four groups as follows:&#x0D; The first group was the control group contained four rats and was administered distilled water only. In contrast, the second group containing four rats was administered garlic at 480 mg/kg body weight. The third group included eight rats, was administered Azithromycin at the dose of 500 mg/kg body weight. The fourth group contained eight rats, and Azithromycin was administrated at 500 mg/k mg+ garlic at 480 mg/kg body weight. The groups were treated with Azithromycin and garlic daily. The results recorded a significant increase (p≥0.05) in sperm head and tail deformation rate in the group administered Azithromycin + garlic compared with the control groups that were administrated distilled water and garlic. Furthermore, the results reported a significant decrease (p≥0.05) in sperm head and tail deformation rates in the group administered Azithromycin + garlic compared with the only Azithromycin administered group. Moreover, the study indicated histological changes in testes tissue included degenerative changes represented by depletion of the spermatogonial cells (some seminiferous tubules appeared with one or two layers of spermatogonia) in the group that was administered Azithromycin compared with the control group, which was administered distilled water and garlic. In addition, the study indicated slight histological changes in testes tissue compared with standard testes architecture, somniferous tubules with the maturation of spermatogony, and sperms inside the lumen in groups administered Azithromycin and garlic compared with control groups, which were administered distilled water and garlic Finally, the findings showed a reduction in histological changes in testes tissue in the group that was administered azithromycin+garlic compared with the group that was administered Azithromycin only..

Combined hydrodynamic and control analysis on optimal kinematic parameters for bio-inspired autonomous underwater vehicle manoeuvring

To investigate the manoeuvring performance of a body-caudal fin robot fish, a numerical framework combining computational fluid dynamics and multi-body dynamics with a closed-loop control algorithm was established in this study. Within this framework, we modelled a body-caudal fin swimmer as a multi-body system with the shape of a NACA0012 hydrofoil. The manoeuvring performance was investigated by using different curvature magnitudes and distributions along the centre line (the curvature is defined by means of a curvature envelop function as part of the general body undulation equation). To characterize the turning performance, a new parameter named cost of manoeuvring (CoM) is proposed. This parameter provides a combined assessment of the turning radius, linear and angular velocity components, and power. It is found that when the body curvature is introduced, the swimmer switches from straight-line swimming to quasi-steady turning at a constant speed. Further investigations were conducted to study contributions of head and tail deformations on the turning performance by comparing predominantly head and tail curved envelopes. Results reveal that a tail-dominated envelope improves performance, whereas a head-dominated envelope has a negative effect.

Automated Orientation Control of Motile Deformable Cells

Automated manipulation of deformable objects is challenging due to the object&#x2019;s deformation behavior. Different from still deformable objects such as wires and cloth, biological organisms such as sperm and worms are both deformable and motile, requiring the control of both deformation and motion. This paper reports automated orientation control of live sperm, as an example of motile deformable cells. Robotic manipulation of human sperm was performed by using a glass micropipette, which is a standard clinical tool, to rotate individual motile sperm. Sperm rotation must be performed before immobilization, as required in clinical cell surgery for infertility treatment. To control tail deformation during sperm rotation, a path planner was designed based on kinematic analysis and manipulation point update. To deal with the intrinsic motion of a motile sperm, a motorized stage was controlled to compensate for sperm swimming motion, and an observer was designed to decouple sperm orientation from its wiggling motion. A sliding mode controller was designed to cope with stiffness variances along the sperm tail and among different sperm. Deep neural networks were developed for robust sperm tail detection, and Kalman filter was used to predict tail motion. Experimental results demonstrated that automated sperm manipulation achieved an orientation error of 0.8<inline-formula> <tex-math notation="LaTeX">$^{\circ}$</tex-math> </inline-formula> and operation time of 6.8 s, both significantly less than those of manual operation. The designed observer was effective to reduce sperm orientation error by reducing the disturbance from sperm wiggling motion. The developed sliding mode controller outperformed the PID controller in operation time, reducing the time of oocyte exposure to the ambient environment. <i>Note to Practitioners</i>&#x2014;This work tackled the challenge of rotating a fast-swimming and deformable sperm in clinical cell surgeries. Automated manipulation of deformable objects has wide applications in industrial and service settings such as manipulating wires and folding cloth. However, the intrinsic motion of a motile sperm and the lack of a rotational degree of freedom in standard micromanipulators pose difficulties to automated sperm manipulation. In this paper, we propose automation techniques for sperm orientation control. For sperm tail detection, deep learning was used to handle the variances of shape and length among different sperm. A path planning strategy and a controller were designed to achieve automated rotation of motile sperm, with its deformation and motion both controlled. The developed methods can be generalized to the manipulation of other deformable objects such as wires, cables and cloth. These objects exhibit significant variance of mechanical properties, and calibration is often time-consuming. The designed controller can be used to manipulate deformable objects with robustness to varied mechanical parameters. Path planning was designed by updating the manipulation point based on the object&#x2019;s deformation behavior, and is suitable in manipulation where constraints are imposed such as the object&#x2019;s strain.

Effects of weak connecting structure on penetration performance of free-flight rocket

The strength of connection between the rocket engine and the warhead has a certain relationship with the warhead’s ballistic characteristics and structural response. In this paper, the effects of weak connecting structure on the penetration performance of the free-flight (unguided) rockets is studied by numerical simulation and experiment. The oblique penetration of free-flight rockets with different connecting structures into armour plates is numerically simulated, the rockets’ deflection in the penetration process is analysed, and the effects of the weak connecting structure on the warhead’s structural integrity are evaluated according to the deformation of the warhead tail. The oblique penetration test of free-flight rocket is designed, and the simulation results under low impact velocities are verified. The research shows that the influence of the length of the weak connecting structure on the tail deformation of the warhead varies at different impact velocities. It is better to use direct connection between the engine and the warhead at high impact velocities, and the weak connecting structure performs better at low impact velocities.

Developmental toxicity of black phosphorus quantum dots in zebrafish (Danio rerio) embryos

Nanomaterials have attracted much attention in the biomedical field. Black phosphorus quantum dots (BPQDs) have shown great potential in biomedical applications, but their potential risks to biosafety and environmental stability have not been fully evaluated. In the present study, zebrafish (Danio rerio) embryos were exposed to 0, 2.5, 5 and 10 mg/L BPQDs from 2 to 144 h post-fertilization (hpf) to explore developmental toxicity. The results showed that exposure to BPQDs for 96 h induced developmental malformations (tail deformation, yolk sac edema, pericardial edema, and spinal curvature) in zebrafish embryos. ROS and antioxidant enzyme activities (CAT, SOD, MDA and T-AOC) were substantially altered and the acetylcholinesterase (AChE) enzyme activity was significantly decreased in the BPQDs exposed groups. Locomotor behavior was inhibited after BPQDs exposure for 144 h in zebrafish larvae. A significant increase in 8-OHdG content indicates DNA oxidative damage in embryos. In addition, obvious apoptotic fluorescence signals were detected in the brain, spine, yolk sac and heart. At the molecular level, the mRNA transcript levels of key genes related to skeletal development (igf1, gh, MyoD and LOX), neurodevelopment (gfap, pomca, bdnf and Mbpa), cardiovascular development (Myh6, Nkx2.5, Myl7, Tbx2b, Tbx5 and Gata4) and apoptosis (p53, Bax, Bcl-2, apaf1, caspase-3 and caspase-9) were abnormal after BPQDs exposure. In conclusion, BPQDs induced morphological malformations, oxidative stress, locomotor behavior disorders, DNA oxidative damage and apoptosis in zebrafish embryos. This study provides a basis for further study on the toxic effects of BPQDs.

Teratogenicity of Dibutyl Phthalate and Polyvinyl Alcohol in Early Developmental Stages of Danio rerio

Dibutyl phthalate (DBP) and polyvinyl alcohol (PVA) are commonly used in manufacturing petroleum-based and biodegradable plastics. Despite being regarded as safe, these chemicals persist as organic pollutants during plastic degradation in aquatic environments and, thus, may pose risks to aquatic organisms and even humans. We performed a 96-h zebrafish embryo test to investigate the toxicity and teratogenicity of DBP and PVA at 25–500 μg/L and 1–3.0% concentrations, respectively. The results showed that exposure to DBP and PVA reduced the survival rate of zebrafish in a concentration and time-dependent manner. In PVA, pericardial edema and heart abnormalities were more common malformations than yolk sack edema and tail deformities in DBP. Reduced body length and hatching rate and elevated heart rates at 400–500 μg/L concentrations were observed in DBP-exposed zebrafish. The same trend was observed in PVA except that decreased heart rate was observed with increasing concentrations. We conclude that DBP and PVA are lethal and teratogenic, even at low concentrations, thus posing questions and concerns about the safety and health, environmental, and ecological risks associated with the use of these chemicals.

Riveting damage behavior and mechanical performance assessments of CFRP/CFRP single-lap gasket-riveted joints

Riveting is one of dominant joining methods in carbon fiber reinforced polymer (CFRP) structures, however, riveting is prone to cause CFRP local damage. In this study, a riveting method with a gasket was developed for CFRP/CFRP joints. Riveting damage behaviors were assessed, and the parametric study of the rivet rod length was also carried out. Moreover, both tensile shear and pull-off performances were assessed under quasi-static loading, including the discussion of failure modes. Results demonstrated that the riveting damage mainly occurred in CFRP plies near the rivet deformed head due to the excessive deformation of the rivet tail along both rivet radial direction and rivet axial direction. The over long rivet rob caused a askew deformation of the rivet tail resulting in the most serious CFRP damage. Joining the CFRP/CFRP structures by using an appropriate gasket can obviously reduce the riveting damage and enhance the joining strength of the composite specimen. This paper provided a useful joining method for aircraft composite structures.

Green Synthesis Iron Oxide Nanoparticles (Fe@AV NPs) Induce Developmental Toxicity and Anxiety-Like Behavior in Zebrafish Embryo-Larvae

The synthesis of nanoparticles and the usage areas of these nanoparticles show a rapid increase. In addition to the beneficial use of nanoparticles, their toxic effects cannot be ignored. In our study, iron oxide nanoparticle (Fe@AV NPs) (mean size: 20.852 nm) was synthesized from Aloe vera plant and the developmental toxicity of zebrafish was investigated. Zebrafish embryo-larvae were treated with different concentrations of Fe@AV NPs (1, 10, and 50 mg/L) starting at 4 hours after fertilization and continuing until 96 hours, and different developmental parameters (such as survival rate, hatchability rates, malformations, and behavior) were examined. In our study, it was determined that Fe@AV NPs caused developmental toxicity in zebrafish embryos depending on the dose increase. More than 60% died at 96 hours, especially in the highest (50 mg/L) application group. It was observed that Fe@AV NPs decreased and delayed the success of exiting the chorion depending on the dose increase, and caused various morphological abnormalities (like pericardial edema, tail deformation, and scoliosis) in all application groups except the lowest application group (1 mg/L). While 10 mg/L Fe@AV NPs caused sleep-like behaviors during the daytime by decreasing the daytime motility of the larvae, it caused hyperactivity by increasing their nocturnal motility. The results of thigmotaxis, which is an anxiety parameter, were found to increase anxiety at 10 mg/L Fe@AV NPs exposure.Our findings showed that Fe@AV NPs synthesized from Aloe vera plant have in vivo toxicity and their use at concentrations lower than 1 mg/L can be safe in environmental and medical applications.

Toxicity of common biocides used in aquaculture to embryos and larvae of Brachymystax tsinlingensis Li.

Brachymystax tsinlingensis Li is a threatened fish species endemic to China. With the problems of environmental factors and seeding breeding diseases, it is important to further improve the efficiency of seeding breeding and the basis of resource protection. This study investigated the acute toxicity of copper, zinc and methylene blue (MB) on hatching, survival, morphology, heart rate (HR) and stress behaviour of B. tsinlingensis. Eggs (diameter: 3.86 ± 0.07 mm, weight: 0.032 ± 0.004 g) of B. tsinlingensis were selected randomly from artificial propagation and developed from eye-pigmentation-stage embryos to yolk-sac stage larvae (length: 12.40 ± 0.02 mm, weight: 0.03 ± 0.001 g) and exposed to different concentrations of Cu, Zn and MB for 144 h in a series of semi-static toxicity tests. The acute toxicity tests indicated that the 96-h median lethal concentration (LC50 ) values of the embryos and larvae were 1.71 and 0.22 mg l-1 for copper and 2.57 and 2.72 mg l-1 for zinc, respectively, whereas the MB LC50 after 144-h exposure for embryos and larvae were 67.88 and 17.81 mg l-1 , respectively. The safe concentrations of copper, zinc and MB were 0.17, 0.77 and 6.79 mg l-1 for embryos and 0.03, 0.03 and 1.78 mg l-1 for larvae, respectively. Copper, zinc and MB treatments with concentrations greater than 1.60, 2.00 and 60.00 mg l-1 , respectively, led to a significantly low hatching rate and significantly high embryo mortality (P < 0.05), and copper and MB treatments with concentrations greater than 0.2 and 20 mg l-1 led to significantly high larvae mortality (P < 0.05). Exposure to copper, zinc and MB resulted in developmental defects, including spinal curvature, tail deformity, vascular system anomalies and discolouration. Moreover, copper exposure significantly reduced the HR of larvae (P < 0.05). The embryos exhibited an obvious change in behaviour, converting from the normal behaviour of emerging from the membrane head first to emerging tail first, with probabilities of 34.82%, 14.81% and 49.07% under copper, zinc and MB treatments, respectively. The results demonstrated that the sensitivity of yolk-sac larvae to copper and MB was significantly higher than that of embryos (P < 0.05) and that B. tsinlingensis embryos or larvae might be more resistant to copper, zinc and MB than other members of the Salmonidae family, which benefits their resource protection and restoration.

Zn-Al layered double hydroxides induce embryo malformations and impair locomotion behavior in Danio rerio

Layered double hydroxides (LDHs) are stimuli-responsive anionic nanoclays. The vast possibilities of using LDHs can lead to their existence in the ecosystem, raising a question of potential ecological concern. However, little is known about the effect of these nanomaterials on freshwater organisms. The present study aimed to assess the ecotoxicological effects of Zinc-Aluminium LDH-nitrate (ZnAl LDH-NO3) in zebrafish (Danio rerio) early life stages. The endpoints measured were mortality, malformations and hatching rate after exposure of D. rerio embryos and larvae to ZnAl LDH-NO3 following the OECD 236 guideline. The behavioral, biochemical (markers of oxidative stress and neurotoxicity), and molecular (at DNA level) alterations were also assessed using sub-lethal concentrations. No observable acute effects were detected up to 415.2 mg LDH/L while the 96 h-LC50 was estimated as 559.9 mg/L. Tested LDH caused malformations in D. rerio embryos, such as pericardial edema, incomplete yolk sac absorption and tail deformities (96 h-EC50 = 172.4 mg/L). During the dark periods, the locomotor behavior in zebrafish larvae was affected upon ZnAl LDH-NO3 exposure. However, no significant biochemical and molecular changes were recorded. The present findings suggest that ZnAl LDH-NO3 can be regarded as a non-toxic nanomaterial towards D. rerio (E/LC50 > > 100 mg/L) although impairment of the locomotion behavior on zebrafish embryos can be expected at concentrations below 100 mg/L.

QNZ exposure induces development toxicity and mechanisms of hatching inhibition in large-scale loach (Paramisgurnus dabryanus) embryos

QNZ is a quinazoline-type NF-κB inhibitor and is one of the hot anti-inflammatory drug candidates in recent years. With its development and application, QNZ will inevitably enter the aquatic environment posing a threat to aquatic organisms. To investigate the potential toxicity of QNZ in the early life stages of the organism, this study exposed embryos of large-scale loach (Paramisgurnus dabryanus) to 0, 20, 40, 60, and 80 nM of QNZ. The hatching of embryos was significantly inhibited and hatching time was delayed. We explored the mechanism of hatching delay and failure. The results suggested that QNZ exposure reduced the number of hatching gland cells (HGCs) and hatching enzyme activity. Also, the frequency of spontaneous movements was inhibited by interfering with the expression of genes related to the cholinergic system and skeletal muscle development. Further, QNZ exposure induces a series of morphological changes (spine deformation, pericardial edema, tail deformation, and yolk sac edema) in embryos and newly-hatched larvae, and finally increased the deformity rate and mortality rate of newly-hatched larvae. The information presented in this study will provide a scientific basis for further studies into the potential toxicity of QNZ on aquatic organisms.

Chronic intake of an enriched diet with spirulina (Arthrospira maxima) alleviates the embryotoxic effects produced by realistic concentrations of tetracycline in Danio rerio

Tetracycline (TC) is one of the most consumed antibiotics worldwide. Due to its high consumption, recent studies have reported its presence in aquatic environments and have assessed its effects on fish, algae, and daphniids. However, in most of those works, authors have tested TC toxicity at concentrations higher than the ones reported in the water matrix. Herein, we aimed to assess the likely embryotoxic and oxidative damage induced by environmentally relevant concentrations of TC in embryos of Danio rerio. Moreover, we seek to determine whether or not an enriched diet with spirulina can alleviate the embryotoxic damage produced by TC. Our findings indicated that TC at concentrations of 50 to 500 ng/L induced pericardial edema, tail deformities, and absence of head and fin in embryos after 96 h of exposure. Moreover, this antibiotic prompted the death of embryos in a concentration-dependent manner. According to our integrated biomarker response index, TC induced oxidative damage on Danio rerio embryos, as star plots showed a tendency to lipoperoxidation, hydroperoxides, and protein carbonyl content. Spirulina reduced the toxicity of TC by diminishing the levels of oxidative damage biomarkers, which resulted in a decrease in the rate of death and malformed embryos. Overall, TC at concentrations of ng/L prompted oxidative stress and embryotoxicity in the early life stages of Danio rerio; nonetheless, the algae spirulina was able to reduce the severity of those effects.