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

Red Swamp Crayfish (Procambarus clarkii) as a Growing Food Source: Opportunities and Challenges in Comprehensive Research and Utilization

The red swamp crayfish (Procambarus clarkii) was introduced from Japan to China in the 1920s. Crayfish are now widely distributed in almost all types of freshwater wetlands, including rice fields, ditches, swamps, lakes, and ponds in most provinces of China, owing to their multi-directional movement, rapid growth, adaptability to the environment, and relatively high fecundity. The delectable taste and high nutritional value of crayfish have made them popular among consumers, leading to the significant development of red swamp crayfish farming in the last two decades. Currently, it represents the largest proportion of commercially farmed freshwater crustaceans in China and has become an integral component of China's aquatic economy. Crayfish are highly valued for their edibility and for their by-products, which have various important uses. This review discusses nutrient composition, active ingredients, safety evaluation, processing and preservation, and comprehensive utilization of crayfish by-products to explore and organize the existing knowledge about crayfish and to promote the growth of the crayfish industry. This comprehensive review aims to provide a basis for the optimal utilization and sustainable development of crayfish resources worldwide.

The effects of dietary supplementation of ginseng stem and leaf saponins on the antioxidant capacity, immune response, and disease resistance of crucian carp, Carassius auratus

This is the first study to explore the positive effects of ginseng stem and leaf saponins (GSLS) on antioxidant capability, immunity, and disease resistance of crucian carp. Seven hundred fifty crucian carps (initial body weight: 25 ± 0.15 g (mean ± SE)) were randomly allocated into five groups with three replicates each; five diets supplemented with the final concentration of 0, 1, 2, 4, and 8 g/kg GSLS were fed to crucian carp for 5 weeks. The results demonstrated that, at a concentration of 8 g/kg, the contents of IgM, C4, SOD, GSH-Px, and the activity of AKP in serum of crucian carp gradually increased at 7, 14, 21, 28, and 35 days, and the expression of immune-relative cytokine genes (TNF-α, IL-10, IFN-γ) in the liver, spleen, and the intestinal tract also had a significant up-regulation (P < 0.05), and which were significant difference compared with control (P < 0.05). The above results demonstrated that dietary GSLS showed enhancement effects on the antioxidant and anti-inflammatory capability, and innate immune response of crucian carp. The feed of 8 g/kg GSLS for 1 week could improve the survival rate 44% more than the control group when crucian carp infected Aeromonas hydrophila (A. hydrophila). In conclusion, the addition of GSLS at a concentration of 8 g/kg in the diet improve immune-related enzyme activity better, immune-relative cytokine expression, and disease resistance.

H2O2-Induced Oxidative Stress Responses in Eriocheir sinensis: Antioxidant Defense and Immune Gene Expression Dynamics

Eriocheir sinensis, a key species in China's freshwater aquaculture, is threatened by various diseases, which were verified to be closely associated with oxidative stress. This study aimed to investigate the response of E. sinensis to hydrogen peroxide (H2O2)-induced oxidative stress to understand the biological processes behind these diseases. Crabs were exposed to different concentrations of H2O2 and their antioxidant enzyme activities and gene expressions for defense and immunity were measured. Results showed that activities of antioxidant enzymes-specificallysuperoxide dismutase (SOD), catalase (CAT), total antioxidant capacity(T-AOC), glutathione (GSH), and glutathione peroxidase (GSH-Px)-varied with exposure concentration and duration, initially increasing then decreasing. Notably, SOD, GSH-Px, and T-AOC activities dropped below control levels at 96 h. Concurrently, oxidative damage markers, including malondialdehyde (MDA), H2O2, and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels, increased with exposure duration. The mRNA expression of SOD, CAT, and GSH-Px also showed an initial increase followed by a decrease, peaking at 72 h. The upregulation of phenoloxidaseloxidase (proPO) and peroxinectin (PX) was also detected, but proPO was suppressed under high levels of H2O2. Heat shock protein 70 (HSP70) expression gradually increased with higher H2O2 concentrations, whereas induced nitrogen monoxide synthase (iNOS) was upregulated but decreased at 96 h. These findings emphasize H2O2's significant impact on the crab's oxidative and immune responses, highlighting the importance of understanding cellular stress responses for disease prevention and therapy development.

Cyfluthrin exposure during pregnancy causes neurotoxicity in offspring-Ca2+ overload via IP3R-GRP75-VDAC1 pathway

Cyfluthrin (Cy) is a widely used pyrethroid insecticide. There is growing evidence that Cy can cause damage to the nervous, reproductive, and immune systems, but there is limited evidence on the potential effects of maternal Cy exposure on offspring. A model of maternal Cy exposure was used to assess its neurobehavioral effects on young-adult offspring. We found that gestational Cy exposure affected pregnancy outcomes and fetal development, and that offspring showed impairments in anxiety as well as learning and memory, accompanied by impairments in hippocampal synaptic ultrastructure and synaptic plasticity. In addition, the IP3R-GRP75-VDAC1 apoptogenic pathway was also upregulated, and in vitro models showed that inhibition of this pathway alleviated neuronal apoptosis as well as synaptic plasticity damage. In conclusion, maternal Cy exposure during pregnancy can cause neurobehavioral abnormalities and synaptic damage in offspring, which may be related to neuronal apoptosis induced by activation of the IP3R-GRP75-VDAC1 pathway in the hippocampus of offspring. Our findings provide clues to understand the neurotoxicity mechanism of maternal Cy exposure to offspring during pregnancy.

Ecological Toxicity of Cyantraniliprole against Procambarus clarkii: Histopathology, Oxidative Stress, and Intestinal Microbiota

Cyantraniliprole is a novel insecticide recently introduced for rice pest control that may cause potential threats to the red swamp crayfish (Procambarus clarkii) in rice-crayfish coculture systems. In this study, we investigated the acute toxicity of cyantraniliprole against P. clarkii with a LC50 value of 149.77 mg/L (96 h), first. Some abnormal behaviors of P. clarkii treated with 125 mg/L cyantraniliprole, including incunabular hyperexcitability, imbalance, inactivity, and increased excretion were observed. Moreover, it was observed that exposure to 5 mg/L cyantraniliprole for 14 days resulted in histopathological alterations in abdominal muscle, gills, hepatopancreas, and intestines. Furthermore, exposure to 0.05 and 5 mg/L cyantraniliprole induced increased activities of several oxidative stress-related enzymes, which was verified by the upregulation of related genes. Additionally, dysregulation of the intestinal microbiota was determined via 16S rRNA sequencing. These results will provide the basis for the utilization of cyantraniliprole in the fields of rice-crayfish integrated system.

Systematic evaluation of the toxicological effects of deltamethrin exposure in zebrafish larvae

Deltamethrin (DM) is a widely used pesticide and has been generally detected in aquatic systems. To systematically investigate the toxic effects, zebrafish embryos were treated with various concentrations of DM for 120h. The LC₅₀ was determined to be 102 μg L^-1. Lethal concentrations of DM induced severe morphological defects in the surviving individuals. Under non-lethal concentrations, DM suppressed the development of neurons in the larvae, which was associated with the reduction in locomotor activity. DM exposure induced cardiovascular toxicity, including suppressed growth of blood vessels and enhanced heart rates. DM also disrupted the development of bones in the larvae. Moreover, liver degeneration, apoptosis and oxidative stress were observed in the larvae treated with DM. Correspondingly, the transcriptional levels of the genes related to the toxic effects were altered by DM. In conclusion, the results obtained in this study provided evidence that DM showed multiple toxic effects on aquatic organisms.

Cyhalofop-butyl and pyribenzoxim-induced oxidative stress and transcriptome changes in the muscle of crayfish (Procambarus clarkii)

Cyhalofop-butyl and pyribenzoxim are commonly used herbicides in rice-crayfish co-culture fields. In actual production, weed control in paddy fields is inseparable from cyhalofop-butyl and pyribenzoxim, while its risk to P. clarkii is still unclear. The present study investigated the risk of acute and subchronic toxicity of cyhalofop-butyl and pyribenzoxim to P. clarkii. The results showed that cyhalofop-butyl and pyribenzoxim exposure for 28 days could accumulate in P. clarkii muscle and inhibit P. clarkii growth. Further research found that the malondialdehyde (MDA) level and glutathione-S-transferase (GST) activity in muscle of P. clarkii were significantly increased after exposure to cyhalofop-butyl and pyribenzoxim (4 days and 28 days), and the superoxide dismutase (SOD) and catalase (CAT) activities were significantly altered. Histological results also confirmed cyhalofop-butyl and pyribenzoxim-induced muscle damage in P. clarkii. Additionally, after 28 days exposure to 1.02 mg/L cyhalofop-butyl and 10.4 mg/L pyribenzoxim, transcriptome analysis identified 2029 and 4246 differentially expressed genes (DEGs), respectively. Exposure to 1.02 mg/L cyhalofop-butyl significantly altered metabolism-related pathways, such as drug metabolism-other enzymes, glutathione metabolism, drug metabolism-cytochrome P450, fatty acid biosynthesis and fatty acid degradation. While the pathways related to antioxidant system and nutrient substances synthesis and metabolic were significantly enriched after exposure to 10.4 mg/L pyribenzoxim. This research has significant implications for scientific and rational use of herbicides under rice-crayfish co-culture and will contribute to the development of the highly productive agricultural model.

The potential immunotoxicity of emamectin benzoate on the human THP-1 macrophages

Emamectin benzoate (EMB) as one of the typical biological pesticides has a wide range of applications in agriculture. However, the immune toxic effects of EMB in human received limited attention. In our study, THP-1 macrophage as an in vitro model was used to evaluate immune functions exposed to EMB. We observed that EMB inhibited phagocytic activity and respiratory burst capacity of macrophages without inducing cellular toxicity, implying the potential immunosuppression. Besides, EMB disturbed the cytokines balance embodied in the increase of TNF-α, IL-1β, IL-6, CCL27, CXCL8 mRNA expression and the decrease of IL-4, IL-13, IL-10 mRNA expression. EMB could exhibit pro-inflammatory responses in macrophages and promote the conversion of macrophages to M1 phenotype. Moreover, NF-κB pathway involved in regulating immune function from KEGG pathway analysis. EMB exposure could activate the NF-κB pathway in THP-1 macrophages by exploring the critical proteins. This research provided insights on immunotoxicity evaluation and clarified EMB-induced immunotoxicity was related to NF-κB pathway activation.

Molecular and biochemical responses to tributyltin (TBT) exposure in the American oyster: Triggers of stress-induced oxidative DNA damage and prooxidant-antioxidant imbalance in tissues by TBT

Environmental pollution increases due to anthropogenic activities. Toxic chemicals in the environment affect the health of aquatic organisms. Tributyltin (TBT) is a toxic chemical widely used as an antifouling paint on boats, hulls, and ships. The toxic effect of TBT is well documented in aquatic organisms; however, little is known about the effects of TBT on DNA lesions in shellfish. The American oyster (Crassostrea virginica, an edible and commercially important species) is an ideal marine mollusk to examine the effects of TBT exposure on DNA lesions and oxidative/nitrative stress. In this study, we investigated the effects of TBT on 8'-hydroxy-2'-deoxyguanosine (8-OHdG, a biomarker of pro-mutagenic DNA lesion), double-stranded DNA (dsDNA), dinitrophenyl protein (DNP, a biomarker on reactive oxygen species, ROS), 3-nitrotyrosine protein (NTP, a biomarker of reactive nitrogen species, RNS), catalase (CAT, an antioxidant), and acetylcholinesterase (AChE, a cholinergic enzyme) expressions in the gills and digestive glands of oysters. We also analyzed extrapallial (EF) fluid conditions. Immunohistochemical and qRT-PCR results showed that TBT exposure significantly increased 8-OHdG, dsDNA, DNP, NTP, and CAT mRNA and/or protein expressions in the gills and digestive glands. However, AChE mRNA and protein expressions, and EP fluid pH and protein concentrations were decreased in TBT-exposed oysters. Taken together, these results suggest that antifouling biocide-induced production of ROS/RNS results in DNA damage, which may lead to decreased cellular functions in oysters. To the best of our knowledge, the present study provides the first molecular/biochemical evidence that TBT exposure results in oxidative/nitrative stress and DNA lesions in oysters.

Transcriptome analysis of the immunomodulatory effects of Salvia miltiorrhiza polysaccharide on hemocyte immune response in Procambarus clarkii

Natural plant polysaccharide as immune modulator is considered an effective strategy for healthy aquaculture to reduce medicine treatment. Salvia miltiorrhiza polysaccharides (SMP) had applications to regulate immune activity and enhance antioxidant in vertebrates, but the potential function has been rarely reported in crustaceans. In this study, the immunological effects of SMP on hemocytes of Procambarus clarkii were analyzed. Results showed that total superoxide dismutase (T-SOD), phenoloxidase (PO) activity and respiratory burst were up-regulated after SMP treatment. After high-throughput sequencing, 2170 differentially expressed genes (DEGs) including 1294 up-regulated and 876 down-regulated genes were identified. KEGG function enrichment analysis indicated that DEGs are involved in crustaceans cellular immune-related signaling pathways, including lysosome, phagosome and endocytosis. Transcriptome mining and qRT-PCR showed that SMP up-regulated humoral immunity factors gene expression. Diets supplemented with 0.8% SMP significantly up-regulated the total number of hemocytes (THC), T-SOD and PO activity, improved the survival of crayfish after Citrobacter freundii infection. This study suggested that SMP could improve the cellular and humoral immunity of P. clarkii. Furthermore, this finding supplied a molecular foundation for further comprehending the immunopotentiator effects of plant polysaccharides in crustaceans.

Microplastic exposure across trophic levels: effects on the host-microbiota of freshwater organisms

BACKGROUND

Microplastics are a pervasive pollutant widespread in the sea and freshwater from anthropogenic sources, and together with the presence of pesticides, they can have physical and chemical effects on aquatic organisms and on their microbiota. Few studies have explored the combined effects of microplastics and pesticides on the host-microbiome, and more importantly, the effects across multiple trophic levels. In this work, we studied the effects of exposure to microplastics and the pesticide deltamethrin on the diversity and abundance of the host-microbiome across a three-level food chain: daphnids-damselfly-dragonflies. Daphnids were the only organism exposed to 1 µm microplastic beads, and they were fed to damselfly larvae. Those damselfly larvae were exposed to deltamethrin and then fed to the dragonfly larvae. The microbiotas of the daphnids, damselflies, and dragonflies were analyzed.

RESULTS

Exposure to microplastics and deltamethrin had a direct effect on the microbiome of the species exposed to these pollutants. An indirect effect was also found since exposure to the pollutants at lower trophic levels showed carry over effects on the diversity and abundance of the microbiome on higher trophic levels, even though the organisms at these levels where not directly exposed to the pollutants. Moreover, the exposure to deltamethrin on the damselflies negatively affected their survival rate in the presence of the dragonfly predator, but no such effects were found on damselflies fed with daphnids that had been exposed to microplastics.

CONCLUSIONS

Our study highlights the importance of evaluating ecotoxicological effects at the community level. Importantly, the indirect exposure to microplastics and pesticides through diet can potentially have bottom-up effects on the trophic webs.

RNA-Seq and 16S rRNA Analysis Revealed the Effect of Deltamethrin on Channel Catfish in the Early Stage of Acute Exposure

Deltamethrin (Del) is a widely used pyrethroid insecticide and a dangerous material that has brought serious problems to the healthy breeding of aquatic animals. However, the toxicological mechanisms of Del on channel catfish remain unclear. In the present study, we exposed channel catfish to 0, 0.5, and 5 μg/L Del for 6 h, and analyzed the changes in histopathology, trunk kidney transcriptome, and intestinal microbiota composition. The pathological analyses showed that a high concentration of Del damaged the intestine and trunk kidney of channel catfish in the early stage. The transcriptome analysis detected 32 and 1837 differentially expressed genes (DEGs) in channel catfish trunk kidneys after exposure to 0.5 and 5 μg/L Del, respectively. Moreover, the KEGG pathway and GO enrichment analyses showed that the apoptosis signaling pathway was significantly enriched, and apoptosis-related DEGs, including cathepsin L, p53, Bax, and caspase-3, were also detected. These results suggested that apoptosis occurs in the trunk kidney of channel catfish in the early stage of acute exposure to Del. We also detected some DEGs and signaling pathways related to immunity and drug metabolism, indicating that early exposure to Del can lead to immunotoxicity and metabolic disorder of channel catfish, which increases the risk of pathogenic infections and energy metabolism disorders. Additionally, 16S rRNA gene sequencing showed that the composition of the intestinal microbiome significantly changed in channel catfish treated with Del. At the phylum level, the abundance of Firmicutes, Fusobacteria, and Actinobacteria significantly decreased in the early stage of Del exposure. At the genus level, the abundance of Romboutsia, Lactobacillus, and Cetobacterium decreased after Del exposure. Overall, early exposure to Del can lead to tissue damage, metabolic disorder, immunotoxicity, and apoptosis in channel catfish, and affect the composition of its intestinal microbiota. Herein, we clarified the toxic effects of Del on channel catfish in the early stage of exposure and explored why fish under Del stress are more vulnerable to microbial infections and slow growth.

Histopathology and transcriptome analysis reveals the gills injury and immunotoxicity in gibel carp following acute deltamethrin exposure

More and more evidences proved that deltamethrin (Del) exposure induced adverse effects and damaged immune function to the aquatic animals in the parasite killing process with increasing insecticide application. However, little is currently known of the negative effect on mucosal immunity, especially in gills tissue. Therefore, this study was aimed to reveal the tissue injury and immunotoxicity in the gill of gibel carp following acute deltamethrin exposure. The LC50 of deltamethrin on gibel carp at 96 h was determined to be 6.194 μg/L, and then juvenile gibel carp (Carassius auratus gibelio) (8.8 ± 1.0 g) were exposed to four Del exposure groups (0.61, 1.22, 2.44, and 4.88 μg/L) for 12 h and 24 h. We measured the lysozyme (LYZ) contents and myeloperoxidase (MPO) activities and found that with increased concentration of Del exposure, the LYZ contents were found to increase in the 1.22 μg/L Del group initially significantly and then gradually significantly decrease in the 4.88 μg/L Del group. And the activities of MPO were significantly lifted in a dose-dependent manner. The histological analysis showed that Del exposure caused serious desquamation and necrosis in the surface of epithelial cells, accompanied by interlamellar cellular mass degenerative. In addition, the mucous cells were significantly decreased in the high Del concentration group (2.44 μg/L and 4.88 μg/L Del group) by AB-PAS staining. Additionally, totally 2857 DEGs (including 1624 up-regulated and 1233 down-regulated genes) were identified between the control group and 4.88 μg/L Del exposure group using transcriptional analysis. Among these, some genes involved in innate immune molecules, complement activation, apoptosis-related molecules, cytokine, and adaptive immune molecules, were also down-regulated. Importantly, we found immune system process and tumor necrosis factor receptor (superfamily) binding pathways were downregulated based on the GO and KEGG enrichment analysis. Meanwhile, we detected the expression of pro-inflammatory cytokines (TNF-α, IFN-γ, IL-1β, and IL-8), anti-inflammatory cytokines (TGF-β), LYZ, IgM, and Hsp70 in the gills tissue at 12 h and 24 h after Del exposure, which were consistent with our sequencing results. Collectively, these results demonstrated that the gills injury and immunotoxicity were induced by Del exposure and provided novel insight for explaining to some extent why Del-exposure fish are more susceptible to concurrent or secondary viral or bacterial infections.

Changes in the Immunity, Histopathology, and Metabolism of Crayfish (Procambarus clarkii) in Response to Drought

Freshwater ecosystems are among the most threatened ecosystems on Earth. The freshwater biodiversity crisis has caused widespread global concern. Drought as one of the factors causing freshwater biodiversity is still poorly understood. Crayfish is often used in academic research as a biological indicator. In this study, flow cytometry, hematoxylin-eosin staining, and untargeted metabolomics were used to analyze the immune function, histopathology, and metabolism of crayfish under drought conditions. After drought exposure, the total hemocytes count (THC) was significantly decreased (from 8.9 × 105 mL−1 in the control group to 2.2 × 105 mL−1 at day 5). Phagocytosis decreased by 66% after 5 days of drought. The level of reactive oxygen species (ROS) in the hepatopancreas was upregulated. Moreover, histological disorder and metabolism changes in the hepatopancreas were obvious. These results indicate that drought suppresses immune function, disrupts the balance of oxidative and antioxidative systems, and induces tissue damage and metabolic changes in crayfish.

How does sublethal permethrin effect non-target aquatic organisms?

Permethrin is belonged to pyrethroids that are one of the substances developed as an alternative to pesticides. Permethrin, which is used especially in agriculture, can bioaccumulate in the water and sediment when mixed into aquatic ecosystems. For this reason, it is necessary to investigate the effect of this substance on aquatic organisms other than the target organism. The aim of this study was the determination of acute and sublethal effects as antioxidant enzyme levels on different organs and hemolymph biochemistry of the non-target aquatic organism, narrow-clawed crayfish (Astacus leptodactylus), after exposure to permethrin, one of the synthetic pyrethroid pesticides, contaminating aquatic ecosystems due to its increase usage. The invertebrate model organism, the narrow-clawed crayfish, was selected for its bioindicator role in food webs as planktivorous grazers epibenthic scavengers and good alternative models in ecotoxicology studies with the importance in conservation of freshwater ecosystems. The 96-h LC₅₀ value of permethrin to experimental species was estimated as 0.903 μg/L (95% CI = 0.5042-2.2734 μg/L) with probit analysis method. The sublethal concentration of the permethrin was determined by 1/10 of 96-h LC₅₀ values as 0.09 μg/L. There were two control (negative and acetone) groups in the experiment. The sampling of hemolymph and the tissues (gills, hepatopancreas, and muscle) were done 48 h and 96 h after exposure of the permethrin. The total hemocyte counts significantly increased in the 96-h exposed group of permethrin (p<0.05). Among the hemolymph biochemical parameters, the hemolymph potassium and chloride values increased statistically (p<0.05). Malondialdehyde levels (MDA) of gills and muscle were significantly increased, whereas the MDA level of the hepatopancreas was significantly decreased at the end of the experiment (p<0.05). Hyperplasia in the lamella was recorded in gills, while the degenerations of the hepatopancreas tissues were observed. According to obtained results, permethrin was extremely toxic as acutely to narrow-clawed crayfish and also effected at sublethal concentrations.