Cytotoxicity induced by abamectin in hepatopancreas cells of Chinese mitten crab, Eriocheir sinensis: An in vitro assay.

Toxic effects of abamectin on non-target aquatic organisms have been well documented due to its extensive use in both agricultural and aquacultural areas. However, knowledge of the abamectin induced cytotoxicity in crustacean hepatopancreas is still incomplete. In this study, we investigated the cytotoxic effects of abamectin on hepatopancreas cells of Chinese mitten crab, Eriocheir sinensis by an in vitro assay. The results showed that abamectin inhibited cell viability with elevated reactive oxygen species (ROS) and malondialdehyde (MDA) levels in a dose-dependent manner. Increased olive tail moment (OTM) values and 8-hydroxy-2'-deoxyguanosine (8-OHdG) contents indicate the DNA damage under abamectin exposure. The up-regulation of the typical apoptosis-related protein BCL2-associated X protein (Bax) and the down-regulation of B cell leukemia/lymphoma 2 (Bcl-2) demonstrate apoptosis in hepatopancreas cells. Meanwhile, the activities of both caspase-3 and caspase-9 were increased, indicating caspase-mediated apoptosis. In addition, qRT-PCR results showed the up-regulation of antioxidant genes superoxide dismutase (SOD) and catalase (CAT). The mRNA expression of Cap 'n' Collar isoform-C (CncC) and c-Jun NH2-terminal kinases (JNK) was also significantly increased, implying the involvement of the Nrf2/MAPK pathway in the antioxidative response. The alteration of innate immune-associated genes Toll-like receptor (TLR) and myeloid differentiation primary response gene 88 (Myd88) also indicates the influence of abamectin on immune status. In summary, the present study reveals the cytotoxicity of abamectin on hepatopancreas cells of E. sinensis and this in vitro cell culture model could be used for further assessment of pesticide toxicity.

Effects of chlorantraniliprole-based pesticide on transcriptional response and gut microbiota of the crucian carp, Carassius carassius.

Chlorantraniliprole (CAP) is a presentative diamide pesticide utilized in agricultural area and as well as rice-fish co-culture system for pest control. However, the understanding of toxic effects of CAP on fish species is still incomplete. In the present study, we performed an integrated study of the acute toxicity and bioaccumulation of CAP on the crucian carp, Carassius carassius, a fish species widely distributed in freshwater area in China and commonly farmed in the rice-fish co-culture systems. Besides, biochemical changes, transcriptional responses and gut microbiota of fish were investigated upon sub-chronic CAP exposure. The results showed that CAP is low toxic to crucian carp with a 96 h LC50 of 74.824 mg/L, but has considerable accumulation in the fish muscles when exposed to 3 mg/L of CAP for 14 d and still detectable after 18 d recovery in fresh water. For sub-chronic test, fish were exposed to CAP at 0, 0.3, 3 and 30 mg/L respectively for 14 d. CAP induced oxidative stress and detoxification inhibition in the liver of fish by decreasing antioxidative and detoxicated enzymes activities and downregulating relevant genes expression. In addition, disrupted gut flora composition was found in all experimental groups by the 16 S rRNA sequencing data, indicating the gut microbiota dysbiosis in crucian carp and potential adverse host effect. All the results suggest that CAP at sublethal concentrations has prominent toxic effect on crucian carp and more attentions should be paid especially using directly in an integrated aquaculture system.

Revitalizing mouse diphyodontic dentition formation by inhibiting the sonic hedgehog signaling pathway.

BACKGROUND: Tooth regeneration depends on the longevity of the dental epithelial lamina. However, the exact mechanism of dental lamina regression has not yet been clarified. To explore the role of the Sonic hedgehog (Shh) signaling pathway in regression process of the rudimentary successional dental lamina (RSDL) in mice, we orally administered a single dose of a Shh signaling pathway inhibitor to pregnant mice between embryonic day 13.0 (E13.0) and E17.0. RESULTS: We observed that the Shh signaling pathway inhibitor effectively inhibited the expression of Shh signaling pathway components and revitalized RSDL during E15.0-E17.0 by promoting cell proliferation. In addition, mRNA-seq, reverse transcription plus polymerase chain reaction (RT-qPCR), and immunohistochemical analyses indicated that diphyodontic dentition formation might be related to FGF signal up-regulation and the Sostdc1-Wnt negative feedback loop. CONCLUSIONS: Overall, our results indicated that the Shh signaling pathway may play an initial role in preventing further development of mouse RSDL in a time-dependent manner.

Osteogenic and angiogenic profiles of the palatal process of the maxilla and the palatal process of the palatine bone.

Hard palate consists anteriorly of the palatal process of the maxilla (ppmx) and posteriorly of the palatal process of the palatine (ppp). Currently, palatal osteogenesis is receiving increasing attention. This is the first study to provide an overview of the osteogenesis process of the mouse hard palate. We found that the period in which avascular mesenchymal condensation becomes a vascularized bone structure corresponds to embryonic day (E) 14.5 to E16.5 in the hard palate. The ppmx and ppp differ remarkably in morphology and molecular respects during osteogenesis. Osteoclasts in the ppmx and ppp are heterogeneous. There was a multinucleated giant osteoclast on the bone surface at the lateral-nasal side of the ppmx, while osteoclasts in the ppp were more abundant and adjacent to blood vessels but were smaller and had fewer nuclei. In addition, bone remodeling in the hard palate was asymmetric and exclusively occurred on the nasal side of the hard palate at E18.5. During angiogenesis, CD31-positive endothelial cells were initially localized in the surrounding of palatal mesenchymal condensation and then invaded the condensation in a sprouting fashion. At the transcriptome level, we found 78 differentially expressed genes related to osteogenesis and angiogenesis between the ppmx and ppp. Fifty-five related genes were up/downregulated from E14.5 to E16.5. Here, we described the morphogenesis and the heterogeneity in the osteogenic and angiogenic genes profiles of the ppmx and ppp, which are significant for subsequent studies of normal and abnormal subjects.

Defining the critical period of hedgehog pathway inhibitor-induced cranial base dysplasia in mice.

BACKGROUND: The hedgehog signaling pathway is critical for developmental patterning of the limb, craniofacial and axial skeleton. Disruption of this pathway in mice leads to a series of structural malformations, but the exact role and critical period of the Hh pathway in the early development of the cranial base have been rarely described. RESULTS: Embryos exposed to vismodegib from E7.5, E9.5, and E10.5 had a higher percentage of cranial base fenestra. The peak incidence of hypoplasia in sphenoid winglets and severe craniosynostosis in cranial base synchondroses was observed when vismodegib was administered between E9.5 and E10.5. Cranial base craniosynostosis results from accelerating terminal differentiation of chondrocytes and premature osteogenesis. CONCLUSIONS: We define the critical periods for the induction of cranial base deformity by vismodegib administration at a meticulous temporal resolution. Our findings suggest that the Hh pathway may play a vital role in the early development of the cranial base. This research also establishes a novel and easy-to-establish mouse model of synostosis in the cranial base using a commercially available pathway-selective inhibitor.

DNA damage, immunotoxicity, and neurotoxicity induced by deltamethrin on the freshwater crayfish, Procambarus clarkii.

Pyrethroid pesticides are applied to both agricultural and aquacultural industries for pest control. However, information of their impact on the commercial important freshwater crayfish, Procambarus clarkii is scarce. Therefore, the present study aimed to characterize to effects of a commonly used pyrethroid pesticide, deltamethrin on DNA damage, immune response, and neurotoxicity in P. clarkii. Animals were exposed to 7, 14, and 28 ng/L of deltamethrin, which correspond to 1/8, 1/4, and 1/2 of the LC50 (96 hours) of this pyrethroid to P. clarkii. Significant increase of olive tail moment (OTM) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) was found after deltamethrin exposure in a dose-dependent way. Total hemocyte counts (THC) and activities of immune-related enzymes including acid phosphatase (ACP), lysozyme (LZM), and phenoloxidase (PO) were all decreased and significantly lower than control at concentration of 28 ng/L after 96 hours exposure. Acetylcholinesterase (AChE) activity, an indicator of neurotoxic effect was investigated and it was decreased significantly in muscles at 14 and 28 ng/L after 24 hours exposure. The level of intracellular reactive oxygen species (ROS) in hemocytes was also measured and the significant increase of ROS was found at 14 and 28 ng/L concentrations. The results revealed that deltamethrin induced DNA damage, immunotoxicity, and neurotoxicity in P. clarkii by excessive generation of ROS. Because of the dose-dependent responses of all parameters under exposure of deltamethrin at environmentally realistic concentrations, these parameters could be used as sensitive biomarkers for risk assessment of deltamethrin in aquaculture area.

Immune response to abamectin-induced oxidative stress in Chinese mitten crab, Eriocheir sinensis.

It is known that abamectin (ABM) inflicts oxidative damage on aquatic animals; however, knowledge about the immune response under pesticide-induced oxidative stress is incomplete. In the present study, several cellular and humoral immune parameters, including total haemocyte counts (THC), lysosomal membrane stability (LMS), activities of acid phosphatase (ACP), alkaline phosphatase (AKP) and lysozyme (LZM) were investigated to reveal the effects of ABM exposure on the immune defence mechanisms of the important freshwater crab, Erocheir sinensis. According to the results, a significant increase of THC was found in low concentration groups (0.03 and 0.06 mg/L), while dramatic decreases occurred in high concentration groups (0.12 and 0.24 mg/L) after 96 h of exposure. We also detected significant increases of reactive oxygen species (ROS) in haemocytes at 0.12 and 0.24 mg/L, and there was a dose- and time-dependent decrease of lysosomal membrane stability. These results suggest that the excessive generation of ROS induced by ABM may be leading the massive collapse of lysosomal membrane, which in turn may be causing the sharp drop of haemocyte counts in E. sinensis. The increase of hydrolytic enzymes ACP and AKP at low concentrations and the decrease at high concentrations also indicate an immune response associated with haemocytes status under stress. However, activities of LZM decreased significantly. After injection of Aeromonas hydrophil, mortalities increased under exposure to ABM and were positively related to ABM concentration. These results confirm that ABM exposure has the ability to impair immune defence and result in the host's susceptibility to pathogens.

Oxidative stress, immunological response, and heat shock proteins induction in the Chinese Mitten Crab, Eriocheir sinensis following avermectin exposure.

In this study, the Chinese mitten crabs, Eriocheir sinensis were exposed to avermectin at 0.03, 0.06, 0.12, 0.24, and 0.48 mg/L respectively for 96 hours. The results showed that levels of superoxide dismutase, catalase, and glutathione peroxidase in hepatopancreas were slightly induced at concentration of 0.03 and 0.06 mg/L, but significantly (P < .05) decreased at higher concentrations, meanwhile similar trend of the activities of acid phosphatase, alkaline phosphatase and lysozyme were observed. Significant induction of HSP70 and HSP90 mRNA expression was detected at 24 hours whereas no significant change was found in HSP60. In addition, levels of reactive oxygen species in hepatocytes increased in dose- and time- dependent manners, and cell viabilities of hepatocytes and haemocytes decreased. These results indicated that sublethal concentration exposure of avermectin had a prominent oxidative stress effect on E. sinensis based on the antioxidative and immunological activity inhibition, and HSP60, 70, and 90 perform a protective response during the exposure.

Antioxidative status, immunological responses, and heat shock protein expression in hepatopancreas of Chinese mitten crab, Eriocheir sinensis under the exposure of glyphosate.

As a broad-spectrum herbicide, glyphosate was extensively utilised in China for several decades. The contradiction between glyphosate spraying and crab breeding in the rice-crab co-culture system has become more obvious. In this study, the antioxidative status and immunological responses of Chinese mitten crab, Eriocheir sinensis, under sublethal exposure of glyphosate were investigated by detecting the antioxidative and immune-related enzyme activity, acetylcholinesterase (AChE) activity and relative mRNA expression of heat shock proteins (HSPs) in hepatopancreas. The results showed that high concentrations of glyphosate (44 and 98 mg/L) could induce significant alteration of superoxide dismutase (SOD), peroxidase (POD), acid phosphatase (ACP), alkaline phosphatase (AKP), and phenoloxidase (PO) activities by first rising then falling during the exposure. However, AChE activity in all treatments including 4.4 mg/L was inhibited markedly after 6 h of exposure. In addition, the relative mRNA expression of HSP 60, HSP 70, and HSP 90 was significantly upregulated at both 48 h and 96 h. These results revealed that glyphosate has a prominent toxic effect on E. sinensis based on antioxidative and immunological response inhibition and AChE activity reduction even at the lowest concentration of 4.4 mg/L, and a protective response by upregulation of HSPs was carried out by the species to ease the environmental stress.

Effects of glyphosate on immune responses and haemocyte DNA damage of Chinese mitten crab, Eriocheir sinensis.

As a broad-spectrum organophosphorus herbicide, glyphosate is widely utilized around the world. The toxic effects of glyphosate on Chinese mitten crab, Eriocheir sinensis, were assessed using immunotoxicity and genotoxicity biomarkers in this study. The results showed that 24 h and 96 h LC50 values of glyphosate for E. sinensis were estimated as 461.54 and 97.89 mg/L, respectively, and the safe concentration was 4.4 mg/L. According to the results above, glyphosate was applied at concentrations of 0, 4.4, 9.8, 44 and 98 mg/L, for 96 h in the exposure experiment. Total haemocyte count (THC) and percentage of granulocytes decreased significantly following 6 h exposure to each concentration of glyphosate and tended to gradually stabilize after 12 h except in 4.4 mg/L, which rapidly recovered to a normal level in 12 h. Phagocytic activity in all treatments decreased dramatically at 6 h and maintained stability until the 96-h mark. Comet tail has been observed early at 24 h in each treatment, and the comet ratio and percentage of DNA (% DNA) in the tail increased as the exposure experiment progressed. Immune-related enzyme activity varied during the experiment. Acid phosphatase (ACP) and alkaline phosphatase (AKP) activities in 44 and 98 mg/L treatments decreased significantly after 48 h exposure, while AKP activities in all concentrations increased markedly at the beginning of exposure. The superoxide dismutase (SOD) and peroxidase (POD) activities increased significantly after 6 h exposure to 44 and 98 mg/L of glyphosates but decreased at 24 h. In addition, the ß-glucuronidase (ß-GD) activities in the 9.8, 44 and 98 mg/L groups, increased after 6-h exposure and were significantly higher than those in the control at 96 h. These results indicated that glyphosate has evident toxic effect on E. sinensis by immune inhibition that is possibly due to the haemocyte DNA damage and a sharp decline in haemocyte numbers, which subsequently induced changes in activities of immune-related enzymes and haemocyte phagocytosis.

Reactive Oxygen Species Signaling and Oxidative Stress: Transcriptional Regulation and Evolution.

Since the evolution of the aerobic metabolism, reactive oxygen species (ROS) have represented significant challenges to diverse life forms. In recent decades, increasing knowledge has revealed a dual role for ROS in cell physiology, showing they serve as a major source of cellular damage while also functioning as important signaling molecules in various biological processes. Our understanding of ROS homeostasis and ROS-mediated cellular signaling pathways has presumed that they are ancient and highly conserved mechanisms shared by most organisms. However, emerging evidence highlights the complexity and plasticity of ROS signaling, particularly in animals that have evolved in extreme environments. In this review, we focus on ROS generation, antioxidative systems and the main signaling pathways that are influenced by ROS. In addition, we discuss ROS's responsive transcription regulation and how it may have been shaped over the course of evolution.

Abamectin-induced behavioral alterations link to energy metabolism disorder and ferroptosis via oxidative stress in Chinese mitten crab, Eriocheir sinensis.

The increasing application of abamectin (ABM) in agriculture has raised concerns regarding its environmental safety and potential adverse effects on aquatic environment safety. In the present study, the toxic effects of ABM exposure on the adult Chinese mitten crab, Eriocheir sinensis were investigated, with a focus on locomotion impairment, behavioral changes, oxidative stress, energy metabolism disruption, and ferroptosis. Crabs were exposed to sublethal concentrations of ABM at 2, 20 and 200 µg/L. After 21 d chronic exposure to 200 µg/L, residual ABM in hepatopancreas and muscles were detected as 12.24 ± 6.67 and 8.75 ± 5.42 µg/Kg, respectively. By using acute exposure experiments (96 h), we observed significant locomotion and behavioral alterations, alongside biochemical evidences of oxidative stress and energy metabolism impairment. The presence of ferroptosis, a form of cell death driven by iron-dependent lipid peroxidation, was notably identified in the hepatopancreas. Functional tests with N-acetylcysteine (NAC) supplementation showed restored behavioral responses and decrease of ferroptosis levels. It suggests that mitigating oxidative stress could counteract ABM-induced toxicity. Our findings highlight the critical roles of oxidative stress and ferroptosis in mediating the toxic effects of ABM on E. sinensis, underscoring the need for strategies to mitigate environmental exposure to pesticides.

Prolonged darkness attenuates imidacloprid toxicity through the brain-gut-microbiome axis in zebrafish, Danio rerio.

The present study investigated the toxic effects of IMI on brain and gut of zebrafish (Danio rerio) by a combination of transcriptome and microbiome analysis. In addition, the involvement of light/dark period was also evaluated. An acute toxic test was conducted on adult zebrafish weighing 0.45 ± 0.02 g with 4 experimental groups (n = 15): 1) IMI group (Light: Dark = 12: 12 h), 2) prolonged light group (Light: Dark = 20: 4 h), 3) prolonged darkness group (Light: Dark = 4: 20 h) which received 20 mg/L of IMI, and 4) control group, which was not treated with IMI (Light: Dark = 12: 12 h). The results showed that prolonged darkness improved the survival rate of zebrafish upon IMI exposure for 96 h. In the sub-chronic test, zebrafish were divided into the same 4 groups and exposed to IMI at 1 mg/L for 14 d (n = 30). The results showed that IMI induced oxidative stress in both IMI and prolonged light groups by inhibition of antioxidant activities and accumulation of oxidative products. Transcriptome analysis revealed a compromise of antioxidation and tryptophan metabolism pathways under IMI exposure. Several genes encoding rate-limiting enzymes in serotonin and melatonin synthesis were all inhibited in both IMI and LL groups. Meanwhile, significant decrease (P < 0.5) of serotonin and melatonin levels was observed. However, there's remarkable improvement of biochemical and transcriptional status in prolonged darkness group. In addition, microbiome analysis showed great alteration of gut bacterial community structure and inhibition of tryptophan metabolism pathway. Similarly, the gut microbiota dysbiosis induced by IMI was alleviated in prolonged darkness. In summary, sub-chronic IMI exposure induced neurotoxicity and gut toxicity in zebrafish by oxidative stress and impaired the brain-gut-axis through tryptophan metabolism perturbation. Prolonged darkness could effectively attenuate the IMI toxicity probably through maintaining a normal tryptophan metabolism.

A New Perspective on the Antimicrobial Mechanism of Berberine Hydrochloride Against Staphylococcus aureus Revealed by Untargeted Metabolomic Studies.

Berberine hydrochloride (BBR) is a natural product widely used in clinical medicine and animal production. It has a variety of antimicrobial effects, but its complex antimicrobial mechanism has not been clarified. This study aimed to discover the metabolic markers and gain a new perspective on the antibacterial mechanism of BBR. The effects of different inhibitory concentrations of BBR on the survival and growth of standard strain Staphylococcus aureus ATCC 25923 were analyzed by the bacteriostatic activity test. Differences in intracellular metabolites of S. aureus following 19 µg/ml BBR exposure for 1 h were investigated by combining non-targeted metabolomics techniques of gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS). The results showed that the minimum inhibitory concentration of BBR against S. aureus was 51 µg/ml. A total of 368 and 3,454 putative metabolites were identified by GC-MS and LC-MS analyses, respectively. Principal component analysis showed the separation of intracellular metabolite profiles between BBR-exposed samples and non-exposed controls. Pathway activity profiling analysis indicated a global inhibition of metabolisms by BBR exposure, while enhancement was also found in nucleic acid metabolism, amino sugar, and nucleotide sugar metabolism. Several metabolic markers were screened out mainly based on their variable importance of projection values. Two pyridine dicarboxylic acids were significantly downregulated, suggesting the reduction of stress resistance. The oxidized phospholipid (PHOOA-PE) was accumulated, while lipid antioxidant gamma-tocopherol was decreased, and farnesyl PP, the synthetic precursor of another antioxidant (staphyloxanthin), was decreased below the detection threshold. This evidence indicates that BBR reduced the antioxidant capacity of S. aureus. Accumulation of the precursors (UDP-GlcNAc, CDP-ribitol, and CDP-glycerol) and downregulation of the key metabolite D-Ala-D-Ala suggest the inhibition of cell wall synthesis, especially the peptidoglycan synthesis. Metabolites involved in the shikimate pathway (such as 3-dehydroshikimate) and downstream aromatic amino acid synthesis were disturbed. This study provides the first metabolomics information on the antibacterial mechanism of BBR against S. aureus. The key metabolic markers screened in this study suggest that the shikimate pathway, staphyloxanthin synthesis, and peptidoglycan biosynthesis are new directions for further study of BBR antibacterial mechanism in the future.

Development and application of an indirect ELISA to detect antibodies to Neospora caninum in cattle based on a chimeric protein rSRS2-SAG1-GRA7.

Neospora caninum is an important apicomplexan parasite causing neosporosis in cattle. The disease is recognized as one of the most important cause of reproductive problems and abortion in cattle worldwide. In this context, we developed an indirect enzyme-linked immunosorbent assays (ELISA) with chimeric protein rSRS2-SAG1-GRA7 to diagnose antibodies to Neospora-infection. This indirect ELISA was compared to indirect fluorescent antibody test (IFAT) and western blotting (WB), and the sensitivity and specificity results of ELISA were calculated to be 86.7 and 96.1%, respectively. The overall coincidence rate was 92.6% using IFAT and WB. Additionally, 329 aborting dairy cattle serum samples were tested using this ELISA to evaluate the prevalence of N. caninum in Ningxia, China. The positive rate of N. caninum in these farms was from 19.05 to 57.89%, and the mean rate was 41.64% (±11.01%), indicating that infection with N. caninum may be one of the important causes of cattle abortion in this region. This established rSRS2-SAG1-GRA7 indirect ELISA is capable for detecting the antibodies against N. caninum, and it could be a useful screening tool for monitoring the epidemiology of neosporosis in cattle.

Imidacloprid induces locomotion impairment of the freshwater crayfish, Procambarus clarkii via neurotoxicity and oxidative stress in digestive system.

Imidacloprid (IMI) is used in integrated farming like the rice-crayfish co-culture system to prevent water weevil. However, the toxic effect of IMI on the freshwater crayfish Procambarus clarkii is unknown. In the current study, the effects of IMI on the locomotion, antioxidative status, digestion and intestinal microbiota of P. clarkii were investigated. The results showed that IMI caused locomotion impairment with reduced crawl velocity, and attenuated their dark preference, aggressiveness and reversal ability. Inhibited AChE in muscle and hepatopancreas indicates the neurotoxicity of IMI which may directly lead their locomotion dysfunction. The increase of antioxidative enzymes activity and MDA level were found after 25 µg/L and 250 µg/L exposure. Significant up-regulation of several antioxidative and immune-related genes, including CZ-SOD, CAT, GPx, GST, AFL, proPO, HSP27 and HSP70 confirmed that oxidative stress was induced in all treatments when exposed to IMI. In addition, there was significant increase of LDH, indicating the different energy allocation during the exposure. Meanwhile, results from DNA damage analysis showed elevated OTM value and 8-OHdG level in hepatopancretic cells. On the other hand, decreases of alpha-amylase, lipase and increase of trypsin in hepatopancreas was observed at 25 and 250 µg/L. In addition, significant changes of composition of intestinal microbiota at both phylum and genus levels were observed according to the 16S rRNA sequencing results. Increase of pathogenic genera and decrease of beneficial bacterial communities revealed the disequilibrium of intestinal flora of crayfish. In summary, results in the present study suggest that IMI at environmentally realistic concentration could induce AChE inhibition and oxidative stress, conjointly leading the locomotion impairment in crayfish. IMI also affected the digestive functions by enzymes inhibition and gut microbiota dysbiosis.

Cytotoxicity induced by abamectin exposure in haemocytes of Chinese mitten crab, Eriocheir sinensis.

Abamectin is widely utilized in both agricultural and aquaculture areas in China for pest control. However, information about toxic effects of abamectin on non-target aquatic organisms is still incomplete. The Chinese mitten crab, Erocheir sinensis has been extensively bred in the rice-crab co-culture system for years, resulting in the frequent exposure to pesticides including abamectin. In the present study, a primary haemocyte culture model was established to investigate the immune response under exposure of abamectin. The results showed that medium osmolarity ranging from 360 to 480 mOsM/Kg was optimal for primary haemocyte culture from E. sinensis. Abamectin could induce significant decrease of cell viability, inhibition of phagocytic activity, as well as decline of acid phosphatase (ACP) and alkaline phosphatase (AKP) activities. All parameters decreased in time- and dose- dependent manners throughout the experiment, indicating the remarkable immunosuppression of abamectin on E. sinensis and also the sensitivity of the cytotoxicology model of haemocytes in vitro under abamectin exposure. In addition, a dose dependent increase of intracellular reactive oxygen species (ROS) was found after 6 h exposure. It revealed that excessive generation of ROS may a main reason to the degradation of cell viability, and moreover, the decrease in immune function.

Effects of imidacloprid on the oxidative stress, detoxification and gut microbiota of Chinese mitten crab, Eriocheir sinensis.

Imidacloprid (IMI) is used in integrated aquaculture systems for pest control and the toxicity of IMI to non-target aquatic animals such as fish and microcrustaceans has been recognised. However, knowledge about the toxic effect of IMI on commercial crabs is still scarce. In the present study, effects of IMI on the acute toxicity, antioxidative status, detoxification systems and gut microbiota in Chinese mitten crab, Erocheir sinensis were investigated. In the present study, the 96-h LC50 of IMI for E. sinensis was 24.97 mg/L. Under sublethal exposure, superoxide dismutase (SOD) activities increased under low concentration (LC, 5 µg/L) and median concentration (MC, 50 µg/L) exposure, but decreased in high concentration group (HC, 500 µg/L). Activities of catalyse (CAT) decreased in a dose-dependent manner. Detoxification-related enzymes aminopyrine N-demethylase (APND) and erythromycin N-demethylase (ERND) increased in all treatments whereas glutathione-S-transferase (GST) decreased dose-dependently. The relative mRNA expression of the cytochrome P4502 (cyp2) gene was induced significantly in LC and HC groups while no significant change was observed in cytochrome P4503 (cyp3) gene. The expression of gst was also significantly decreased in HC group. Up-regulation of heat shock protein hsp70 and 90 was observed in MC and HC groups whereas hsp60 up-regulated only in LC group. In addition, significant changes of composition of microbial communities at both phylum and genus levels were found in this test. In particular, beneficial bacteria were found to decrease and pathogens increased after exposure to IMI. These results indicate that high concentration of IMI could induce oxidative stress and suppress the detoxification system mainly by down-regulation of gst mRNA expression, inhibition of enzyme activities and dysbiosis of gut microbiota.

Abamectin at environmentally-realistic concentrations cause oxidative stress and genotoxic damage in juvenile fish (Schizothorax prenanti).

Abamectin (ABM) has been extensively used in Chinese aquaculture systems for parasite control, but no information is available regarding its effects on the important freshwater commercial fish species Schizothorax prenanti. We performed an acute toxicity test to determine the effects of ABM on S. prenanti, and the 48- and 96-h median lethal concentration values were 33.32 and 15.98 µg/L, respectively. In a second test, animals were exposed to sublethal concentrations of ABM (0.5, 2 or 8 µg/L) for 8 days, and various cytological and biochemical parameters were measured. ABM caused DNA damage in hepatocytes, with significant increases in Olive Tail Moment values and 8-hydroxy-2'-deoxyguanosine levels. Hepatocytic apoptosis occurred following all treatments, and was accompanied by an increase in reactive oxygen species (ROS) generation and caspase activity in a dose- and time-dependent manner. In addition, there were significant decreases in glutathione peroxidase levels and superoxide dismutase and catalase activity and increases in malonaldehyde levels. ABM-induced hepatocytic apoptosis in S. prenanti was probably triggered by ROS generation following a cascade reaction of caspases in mitochondrial or death receptor pathways, which caused antioxidant inhibition, oxidative product accumulation, and DNA damage in the liver.

Avermectin induces the oxidative stress, genotoxicity, and immunological responses in the Chinese Mitten Crab, Eriocheir sinensis.

Avermectin is commonly used in aquaculture systems for pest control in recent decades in China. However, no information is provided for the toxic effect to the important commercial species, Chinese mitten crab, Eriocheir sinensis. To investigate the aquatic toxicity of avermectin, an acute toxic test was performed in this study. The results showed that the 48 h- and 96 h- LC50 were 1.663 and 0.954 mg/L, respectively. For further research, crabs were exposed to sublethal concentrations of 0.03, 0.06, 0.12, 0.24 and 0.48 mg/L. Levels of antioxidants, including superoxide dismutase (SOD), catalase (CAT) and total antioxidant capacity (T-AOC) were significantly (P<0.05) decreased with dose- and time- dependent responses, meanwhile the oxidative products including malondialdehyde (MDA), hydrogen peroxide (H2O2) and protein carbonyl in serum increased significantly (P<0.05) at concentrations of 0.24 and 0.48 mg/L throughout the experiment. A significant (P<0.05) increase of intracellular ROS and decrease of phagocytic activity was observed in high concentration groups, with dose- and time- dependent manners during the exposure. In addition, serious genetic damage was detected, for the significant increase (P<0.05) of both comet ratio and %DNA in tail at each concentration, and micronucleus (MN) frequency at concentrations of 0.12, 0.24 and 0.48 mg/L at 96 h. These results indicated that sublethal concentration exposure of avermectin had a prominent toxic effect on E. sinensis based on the oxidative stress induced by generated ROS, immunological activity inhibition and genotoxicity.