Effects of dietary monoterpene, myrcene, administration on immune- and health-related genes expression in common carp gill following exposure to copper sulfate

Effect of Copper Sulphate Exposure on the Oxidative Stress, Gill Transcriptome and External Microbiota of Yellow Catfish, Pelteobagrus fulvidraco

This study aimed to investigate the potential adverse effects of the practical application of copper sulfate on yellow catfish (Pelteobagrus fulvidraco) and to provide insights into the gill toxicity induced by copper sulphate. Yellow catfish were exposed to a conventional anthelmintic concentration of copper sulphate (0.7 mg/L) for seven days. Oxidative stress biomarkers, transcriptome, and external microbiota of gills were examined using enzymatic assays, RNA-sequencing, and 16S rDNA analysis, respectively. Copper sulphate exposure led to oxidative stress and immunosuppression in the gills, with increased levels of oxidative stress biomarkers and altered expression of immune-related differentially expressed genes (DEGs), such as IL-1β, IL4Rα, and CCL24. Key pathways involved in the response included cytokine-cytokine receptor interaction, NOD-like receptor signaling pathway, and Toll-like receptor signaling pathway. The 16S rDNA analysis revealed copper sulphate altered the diversity and composition of gill microbiota, as evidenced by a significant decrease in the abundance of Bacteroidotas and Bdellovibrionota and a significant increase in the abundance of Proteobacteria. Notably, a substantial 8.5-fold increase in the abundance of Plesiomonas was also observed at the genus level. Our findings demonstrated that copper sulphate induced oxidative stress, immunosuppression, and gill microflora dysbiosis in yellow catfish. These findings highlight the need for sustainable management practices and alternative therapeutic strategies in the aquaculture industry to mitigate the adverse effects of copper sulphate on fish and other aquatic organisms.

Exposure to nitrate induces alterations in blood parameter responses, liver immunity, and lipid metabolism in juvenile turbot (Scophthalmus maximus)

Nitrate (NO₃^-) pollution of waterbodies has attracted significant global attention as it poses a serious threat to aquatic organisms and human beings. This study aimed to evaluate the role of NO₃^-, an end product of biological nitrification processes, in immune status and lipid metabolism to have a comprehensive understanding of its toxic effects on fishes. Therefore, in this work, juvenile turbot (Scophthalmus maximus) were subjected to four nominal concentrations of NO₃^- (i.e., 0, 50, 200, 400 mg/L of NO₃^--N) for a 60-day period. The results indicated that increased exposure to NO₃^- (200 and/or 400 mg/L) enhanced the concentrations of plasma heat shock protein concentrations (HSP70), complement component 3 (C3), complement component 4 (C4), immunoglobulin M (IgM) and lysozyme (LYS), which meant that NO₃^-caused fluctuations in the plasma immune system. Higher exposure to NO₃^- (200 and/or 400 mg/L) also caused significant enhancements in plasma glutamic pyruvic transaminase (GPT), as well as glutamic oxaloacetic transaminase (GOT) activity. Furthermore, NO₃^- exposure resulted in upregulation of liver TNF-α, IL-1β, HSP70, HSP90, and LYS. Additionally, the results suggested that NO₃^-exposure caused a certain degree of histological damage and inflammation in the liver and activated the immune defense processes of juvenile turbot. Furthermore, the mRNA expression levels of certain genes associated with lipid metabolism (peroxisome proliferator-activated receptor-alpha [PPAR-α], carnitine palmitoyltransferase 1[CPT1], liver X receptor [LXR] together with sterol regulatory element binding protein-1 [SREBP-1]) increased significantly within fish liver exposed to 200/400 mg/L NO₃^--N treatments. Finally, the results obtained from the analysis of the integrated biological responses version 2 (IBRv2) also confirmed the toxic effects of NO₃^- on juvenile turbot. According to these findings, it can be found that NO₃^- emission in the aquatic environment needs to be strictly controlled, as it may cause immune and lipid metabolism disorders in fish.

Potential protective effects of Thyme (Thymus vulgaris) essential oil on growth, hematology, immune responses, and antioxidant status of Oncorhynchus mykiss exposed to Malathion

As an abundant source of antioxidants and diet flavor enhancers, the plant essential oils can have positive effects on fish growth, and resistance against environmental stressors. In this study, garden thyme (Thymus vulgaris) essential oil (TEO) was used in the diet of rainbow trout, Oncorhynchus mykiss, to evaluate its protective effect against Malathion pesticide exposure. Tested fish (19.99 ± 0.01 g) were divided into six groups (three replicates), namely: T1: control diet; T2: control diet + 0.025 mg L−1 malathion; T3: control diet + 0.075 mg L−1 malathion; T4: control diet + 1% TEO; T5: control diet + 0.025 mg L−1 malathion + 1% TEO and T6: control diet + 0.075 mg L−1 malathion + 1% TEO. After 21 days, T4 fish had the highest final body weight (FW), weight gain (WG), specific growth rate (SGR), and the lowest feed conversion ratio (FCR) among experimental treatments (P<0.05). The blood parameters including the red blood cells (RBC), white blood cell count (WBC), hematocrit (Hct), and hemoglobin (Hb) values were the highest in T4 treatment, displaying a significant difference with T1 treatment (P<0.05). Fish in the T4 groups had the highest total protein (TP) and albumin (ALB), while fish of T3 showed the lowest levels of these parameters (P<0.05) and also had the highest level of triglycerides (TRG), cholesterol (CHOL), lactate dehydrogenase (LDH), and urea (Ur). Alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) enzymes recorded the lowest levels in T4 treatment, which showed a significant difference with T1 group. The catalase (CAT) and superoxide dismutase (SOD) showed the highest activities in T4 treatment, while the lowest SOD and the highest malondialdehyde (MDA) levels occurred in T3 group (P<0.05). Total immunoglobulin (total Ig) level, alternative complement (ACH50) and lysozyme in the serum and skin mucus of T4 treatment of rainbow trout showed the highest activities with a significant difference from groups (P<0.05). From the results of the present study, it can be concluded that 1% of T. vulgaris as a supplement to the diet of rainbow trout can stimulate and improve the immune system of the fish. TEO can have a protective effect against unfavorable effects of malathion and improves the growth of the fish.

Neurotoxicity of singular and combined exposure of Oreochromis niloticus to methomyl and copper sulphate at environmentally relevant levels: Assessment of neurotransmitters, neural stress, oxidative injury and histopathological changes

Aquatic organisms are concomitantly exposed to multiple noxious chemicals that can be discharged into water bodies. We aimed to investigate the single and simultaneous sub-acute exposure to copper and methomyl on juvenile Oreochromis niloticus. Compared to the controls, the outcomes revealed that brain of methomyl-exposed fish displayed significant declines in the activities of SOD, CAT, and GST in addition to higher MDA and lower GSH levels. Methomyl induced notable declines in levels of GABA and acetylcholine esterase in brain and muscle of exposed fish. Noteworthy downregulated gene expression levels of TNF-α, HSP-70 together with upregulated c-fos were evident in brain of fish expose to either of tested compounds. Marked apoptotic changes were observed in fish brain exposed to copper and methomyl indicated by augmented immune expression of caspase-3. Conclusively, the results indicated the possible interaction between both compounds with subsequent toxic effects that differ from their single exposure.

Hsp70 overexpression in Drosophila hemocytes attenuates benzene-induced immune and developmental toxicity via regulating ROS/JNK signaling pathway

Benzene, a ubiquitous environmental chemical, is known to cause immune dysfunction and developmental defects. This study aims to investigate the relation between benzene-induced immune dysfunction and developmental toxicity in a genetically tractable animal model, Drosophila melanogaster. Further, the study explored the protective role of Heat Shock Protein 70 (Hsp70) against benzene-induced immunotoxicity and subsequent developmental impact. Drosophila larvae exposed to benzene (1.0, 10.0, and 100.0 mM) were examined for total hemocyte (immune cells) count, phagocytic activity, oxidative stress, apoptosis, and their developmental delay and reduction were analyzed. Benzene exposure for 48 h reduced the total hemocytes count and phagocytic activity, along with an increase in the Reactive Oxygen Species (ROS), and lipid peroxidation in the larval hemocytes. Subsequently, JNK-dependent activation of the apoptosis (Caspase-3 dependent) was also observed. During their development, benzene exposure to Drosophila larvae led to 3 days of delay in development, and ~40% reduced adult emergence. Hsp70-overexpression in hemocytes was found to mitigate benzene-induced oxidative stress and abrogated the JNK-mediated apoptosis in hemocytes, thus restoring total hemocyte count and improving phagocytotic activity. Further, hsp70-overexpression in hemocytes also lessened the benzene-induced developmental delay (rescue of 2.5 days) and improved adult emergence (~20%) emergence, revealing a possible control of immune cells on the organism's development and survival. Overall, this study established that hsp70-overexpression in the Drosophila hemocytes confers protection against benzene-induced immune injury via regulating the ROS/JNK signaling pathway, which helps in the organism's survival and development.

Effect of Dietary Sugarcane Bagasse Supplementation on Growth Performance, Immune Response, and Immune and Antioxidant-Related Gene Expressions of Nile Tilapia (Oreochromis niloticus) Cultured under Biofloc System

Simple Summary

Supplementation of agriculture by-product as functional feed additives in combination with biofloc technology (a sustainable and environmentally friendly technology) has recently gained much attention in aquaculture. In the present study, sugarcane bagasse powder can possibly be applied as a feed additive to improve growth performance, immune response, and immune and antioxidant-related gene expression.

Abstract

We investigated, herein, the effects of dietary inclusion of sugarcane bagasse powder (SB) on Nile tilapia development, mucosal and serum immunities, and relative immune and antioxidant genes. Fish (15.12 ± 0.04 g) were provided a basal diet (SB0) or basal diet incorporated with SB at 10 (SB10), 20 (SB20), 40 (SB40), or 80 (SB80) g kg⁻¹ for 8 weeks. Our results demonstrated that the dietary incorporation of sugarcane bagasse powder (SB) at 20 and 40 g kg⁻¹ significantly ameliorated FW, WG, and SGR as opposed to fish fed basal, SB10, and SB80 diets. However, no significant changes in FCR and survivability were observed between the SB supplemented diets and the control (basal diet). The mucosal immunity exhibited significantly higher SMLA and SMPA activities (p < 0.005) in fish treated with SB diets after eight weeks. The highest SMLA and SMPA levels were recorded in fish fed SB80 followed by SB20, SB40, and SB10, respectively. For serum immunity, fish fed SB incorporated diets significantly ameliorated SL and RB levels (p < 0.05) compared with the control. However, SP was not affected by the inclusion of SB in any diet throughout the experiment. The expression of IL1, IL8, LBP, GSTa, GPX, and GSR genes in the fish liver was significantly increased in fish fed the SB20 and SB10 diets relative to the basal diet fed fish (p < 0.05); whereas only the IL8, LBP, and GPX genes in the intestines were substantially augmented via the SB20 and SB80 diets (p < 0.05). IL1 and GSR were not influenced by the SB incorporated diets (p > 0.05). In summary, sugarcane bagasse powder (SB) may be applied as a feed additive to improve growth performance, immune response, and immune and antioxidant-related gene expression in Nile tilapia.