Acute toxicity, biochemical and transcriptomic analysis of Procambarus clarkii exposed to avermectin

Effect of abamectin on osmoregulation in red swamp crayfish (Procambarus clarkii)

As a widely used pesticide, abamectin could be a threat to nontarget organisms. In this study, the toxic mechanism of abamectin on osmoregulation in Procambarus clarkii was explored for the first time. The results of this study showed that with increasing abamectin concentration, the membrane structures of gill filaments were damaged, with changes in ATPase activities, transporter contents, biogenic amine contents, and gene expression levels. The results of this study indicated that at 0.2 mg/L abamectin, ion diffusion could maintain osmoregulation. At 0.4 mg/L abamectin, passive transport was inhibited due to damage to the membrane structures of gill filaments, and active transport needed to be enhanced for osmoregulation. At 0.6 mg/L abamectin, the membrane structures of gill filaments were seriously damaged, and the expression level of osmoregulation-related genes decreased, but the organisms were still mobilizing various transporters, ATPases, and biogenic amines to address abamectin stress. This study provided a theoretical basis for further study of the effects of contaminations in aquatic environment on the health of crustaceans.

Antibiotics in the rice-crayfish rotation pattern: Occurrence, prioritization, and resistance risk

Antibiotics are extensively utilized in aquaculture to mitigate diseases and augment the productivity of aquatic commodities. However, to date, there have been no reports on the presence and associated risks of antibiotics in the emergent rice-crayfish rotation (RCR) system. This study investigated the occurrence, temporal dynamics, prioritization, sources, and potential for resistance development of 15 antibiotics within the RCR ecosystem. The findings revealed that during the crayfish breeding and rice planting periods, florfenicol (FFC) predominated in the RCR's surface water, with peak and average concentrations of 1219.70 ng/L and 57.43 ng/L, and 1280.70 ng/L and 52.60 ng/L, respectively. Meanwhile, enrofloxacin (ENX) was the primary antibiotic detected in RCR soil and its maximum and average concentrations were 624.73 ng/L and 69.02 ng/L in the crayfish breeding period, and 871.27 ng/L and 45.89 ng/L in the rice planting period. Throughout the adjustment period, antibiotic concentrations remained relatively stable in both phases. Notably, antibiotic levels in surface water and soil escalated during the crayfish breeding period and subsided during the rice planting period, with these fluctuations predominantly influenced by FFC and ENX. Source analysis indicated that the antibiotics in RCR predominantly originated from aquaculture activities, supplemented by water exchange processes. Utilizing the entropy utility function and a resistance development model, FFC, clarithromycin (CLR), and roxithromycin (ROX) in surface water, along with ENX, CLR, and ROX in soil, were identified as priority antibiotics. FFC, ENX, and ROX exhibited a medium risk for resistance development. Consequently, this study underscores the necessity to intensify antibiotic usage control during the crayfish breeding period in the RCR system to mitigate environmental risks.

Effects of chronic abamectin stress on growth performance, digestive capacity, and defense systems in red swamp crayfish (Procambarus clarkii)

Abamectin is a globally used pesticide, which is one of 16-member macrocyclic lactones compound. As an environmental contaminant, pesticide residues pose a great threat to the health and survival of aquatic animals. Procambarus clarkii is one of the most important economic aquatic animals in China. It is necessary to explore the toxic mechanism of abamectin to P. clarkii. In this study, the toxic mechanism of abamectin to P. clarkii was investigated by 0, 3 and 6 μg/L abamectin stress for 28 days. The digestive-, antioxidant- and immune- related enzymes activities, genes expression levels, and histological observations were analytical indicators of growth performance, digestive capacity, and defense systems. The results in this study showed that with abamectin concentration increasing, the growth of P. clarkii was stunted significantly, and the mortality rate increased significantly. With exposure time and abamectin concentration increasing, the expression levels of related genes, the activities of digestive-, antioxidant-, and immune- related enzymes decreased ultimately. Moreover, through histological observation, it was found that with abamectin concentration increasing, the hepatopancreas, muscle, and intestine were damaged. As elucidated by the results, once abamectin exists in the environment for a long time, even low doses will threaten to healthy growth and survival of P. clarkii. This study explored the potential toxicity and the toxic mechanism of abamectin to P. clarkii, and provides a theoretical basis for further study on the toxicity of pesticides to aquatic animals.

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.

Effects of abamectin on nonspecific immunity, antioxidation, and apoptosis in red swamp crayfish (Procambarus clarkii)

Abamectin, a pesticide of 16-member macrocyclic lactones, is widely applied in agriculture. As an important environmental factor, pesticides pose a great threat to defense system in aquatic animals. Procambarus clarkii is one of the most important economic aquatic animals in China. It is necessary to explore the defense mechanism of P. clarkii to abamectin. In this study, P. clarkii were exposed to 0, 0.2, 0.4, 0.6 mg/L abamectin, immune- and antioxidant-related enzymes activities, genes expression levels, and histological observations were used to analyze the defense capacity of P. clarkii to abamectin. With increasing abamectin concentration, reactive oxygen species (ROS) level and malondiadehyde (MDA) content increased significantly. Meanwhiile, acid phosphate (ACP), alkaline phosphatase (AKP) activities, total haemocyte counts (THC), and Crustin expression level decreased significantly, superoxide dismutase (SOD), catalase (CAT) activities, total antioxidant capacity (T-AOC), and GPX expression level also decreased significantly. Hematoxylin & eosin (H&E) observation showed that with increasing abamectin concentration, hepatopancreas were damaged, especially membrane structure. Through TUNEL observation and apoptosis-related genes (PcCTSL, Bcl-2, Bax, BI-1, PcCytc, caspase-3) expression levels, with increasing abamectin concentration, apoptosis rate increased significantly. Results of this study indicated that abamectin caused oxidative damage to P. clarkii, resulting in damage to defense system, suppression of nonspecific immunity and antioxidation, and promotion of apoptosis. It provided theoretical basis for healthy P. clarkii culture, and for further study on defense mechanism of aquatic animals to pesticides.

Using crayfish behavior assay as a simple and sensitive model to evaluate potential adverse effects of water pollution: Emphasis on antidepressants

The freshwater crayfish, Procambarus clarkii is an excellent aquatic animal model that is highly adaptable and tolerant. P. clarkii is widely used as a toxicity model to study various pharmaceutical exposure. This animal model has complex behavioral traits and is considered sensitive to environmental changes, making it an excellent candidate to study psychoactive drugs based on a behavioral approach. However, up to now, most behavioral studies on crayfish use manual observation and scoring that require panelists. In this study, we aim to develop an automation pipeline to analyze crayfish behavior automatically. We use a deep-learning approach to label body parts in multiple crayfish, and based on the trajectory results, the intra- or inter-individual crayfish were calculated. Reliable and fast results of several behavior endpoints in multiple crayfish were retrieved. We then validated the detection performance of numerous crayfish in specific gender groups (male-male and female-female). Based on the result, the male crayfish displayed significantly higher aggression than females. We also tested the antidepressant exposure on this animal model to evaluate the psychoactive effects of this drug. As male crayfish display more distinct agonistic behavior than females, we exposed them to sertraline (SRT) 1 ppb for 7 and 14 days. It was revealed that sertraline was able to alter several behavioral endpoints in crayfish. Significant increases in extend claw ratio, total distance moved, average speed, and rapid movement were displayed in sertraline-exposed crayfish but decreased interaction time and longest interaction time. In addition, SRT 14 days exposure could atler the aggressiveness and bold behavior In the present method, DeepLabCut (DLC) has been utilized to analyze the locomotion behavior of multiple crayfish. This established method provides rapid and accurate ecotoxicity measurements using freshwater crayfish, which beneficient and applicable for environmental research.