Bacterial screening in Indian coastal regions for efficient polypropylene microplastics biodegradation

Polypropylene based medical devices significantly increased production and usage in COVID-19 pandemic states, and this material is very resilient in the environment. Thus, more than ever, rapid action is needed to reduce this pollution. This study focuses on the degradation of polypropylene microplastics (PP MPs) by unique marine bacterial strains obtained from the Thoundi (Bacillus tropicus, Bacillus cereus, Stenotrophomonas acidaminiphila, and Brucella pseudintermedia) and Rameshwaram coasts (Bacillus cereus). Those above five bacterial strains were chosen after preliminary screening of their hydrophobicity, biofilm-forming capabilities, and responsiveness to the zone of clearance technique. During the biodegradation process (28 days), the growth, metabolic activity, and viability of these five isolates were all raised. After the post-biodegradation process, the weight loss percentages of the mentioned bacterial strains treated with PP MPs gradually decreased, with values of 51.5 ± 0.5 %, 47.5 ± 0.5 %, 33 ± 1 %, 28.5 ± 0.5 and 35.5 ± 0.5 %, respectively. UV-Vis DRS and SEM analysis confirmed that bacterial strains adhering to MPs cause cracks and cavities on their surface. The degradation of PP MPs can be inferred from alterations in the FT-IR spectrum, specifically in the carbonyl group range of 1100-1700 cm-1, as well as changes in the 1H NMR spectrum, including chemical shift and proton peak pattern alterations. Bacterial strains facilitated the degradation of PP MPs through the secretion of hydrolase-categorized enzymes of protease, lipase, and esterase. The findings of this study indicate that marine bacteria may possess distinctive characteristics that facilitate the degradation of plastic waste and contribute to environmental conservation.

Exploring the artificial intelligence and machine learning models in the context of drug design difficulties and future potential for the pharmaceutical sectors

Artificial intelligence (AI), particularly deep learning as a subcategory of AI, provides opportunities to accelerate and improve the process of discovering and developing new drugs. The use of AI in drug discovery is still in its early stages, but it has the potential to revolutionize the way new drugs are discovered and developed. As AI technology continues to evolve, it is likely that AI will play an even greater role in the future of drug discovery. AI is used to identify new drug targets, design new molecules, and predict the efficacy and safety of potential drugs. The inclusion of AI in drug discovery can screen millions of compounds in a matter of hours, identifying potential drug candidates that would have taken years to find using traditional methods. AI is highly utilized in the pharmaceutical industry by optimizing processes, reducing waste, and ensuring quality control. This review covers much-needed topics, including the different types of machine-learning techniques, their applications in drug discovery, and the challenges and limitations of using machine learning in this field. The state-of-the-art of AI-assisted pharmaceutical discovery is described, covering applications in structure and ligand-based virtual screening, de novo drug creation, prediction of physicochemical and pharmacokinetic properties, drug repurposing, and related topics. Finally, many obstacles and limits of present approaches are outlined, with an eye on potential future avenues for AI-assisted drug discovery and design.

Response of hepatic biochemical parameters and neurotoxicity to carbamazepine and ibuprofen in Oreochromis mossambicus

Globally, the prevalence and pollution of pharmaceutical drugs in aquatic environments have been steadily increasing. This study sought to evaluate the effects of 14 days of exposure to environmental-relevant doses (ibuprofen 0.5, 5, and 50 µg/L, and carbamazepine 0.005, 1, and 10 µg/L) of the nonsteroidal anti-inflammatory drugs ibuprofen and carbamazepine in the freshwater fish Oreochromis mossambicus. The results showed a significant (P < 0.05) decrease in O. mossambicus superoxide dismutase, catalase, biotransformation enzymes, glutathione-s-transferase, glutathione peroxidase, oxidative stress lipid peroxidation, protein carbonyl activity, cellular damage metallothionine, reduced glutathione, immunological activities, and respiratory burst activity. Consequently, the acquired data revealed that O. mossambicus treated with ibuprofen and carbamazepine shows more significant alterations in metabolic depression, biochemical parameters, and oxidative stress. In addition, increased neurotoxic effects were observed in ibuprofen and carbamazepine treated O. mossambicus.

Combined toxic effects of environmental predominant microplastics and ZnO nanoparticles in freshwater snail Pomaceae paludosa

In the past few years, microplastics are one of the ubiquitous threatening pollutants in aquatic habitats. These persistent microplastics interact with other pollutants, especially nanoparticles were adherent on the surface, which causes potential hazards in the biota. In this study, the toxic effects of individual and combined (28 days) exposure with zinc oxide nanoparticles and polypropylene microplastics were assessed in freshwater snail Pomeacea paludosa. After the experiment, the toxic effect was evaluated by the estimation of vital biomarkers activities including antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), oxidative stress in carbonyl protein (CP), lipid peroxidation (LPO), and digestive enzymes (esterase and alkaline phosphatase). Chronic exposure to pollutants in snails causes increased reactive oxygen species level (ROS) and generates free radicals in their body which leads to impairment and alterations of biochemical markers. Where alteration in acetylcholine esterase (AChE) activity and decreased digestive enzymes (esterase and alkaline phosphatase) activities were observed in both individual and combined exposed groups. Further, histology results revealed the reduction of haemocyte cells, the disintegration of blood vessels, digestive cells, calcium cells, and DNA damage was also detected in the treated animals. Overall, when compared to individual exposures, combined exposure of pollutants (zinc oxide nanoparticles and polypropylene microplastics) causes more serious harms including decline and increased antioxidant enzyme parameters, damage the protein and lipids by oxidative stress, increased neurotransmitter activity, decrease digestive enzyme activities in the freshwater snail. The outcome of this study concluded that polypropylene microplastics along with nanoparticles cause severe ecological threats and physio-chemical effects on the freshwater ecosystem.

Exopolysaccharides-Mediated ZnO Nanoparticles for the Treatment of Aquatic Diseases in Freshwater Fish Oreochromis mossambicus

Bacterial fish disease outbreaks are a key concern for aquaculture. Complementary feed additives such as immunostimulants can serve as an ideal solution for disease prevention. Herein, we scrutinized the efficacy of exopolysaccharides (EPSs) from probiotic Bacillus licheniformis and EPS-mediated zinc oxide nanoparticles (EPS-ZnO NPs) for a diet to evaluate growth parameters, antioxidant enzyme activities, and immune stimulation together with disease resistance against Aeromonas hydrophila and Vibrio parahaemolyticus in Mozambique tilapia Oreochromis mossambicus. Fish were separated into seven groups, with six experimental groups fed with EPS and EPS-ZnO NPs at 2, 5, and 10 mg/g and a control fed a basal diet. The fish ingesting feed supplemented with EPS and EPS-ZnO NPs at 10 mg/g showed improved growth performance. Cellular and humoral-immunological parameters were tested in serum and mucus after 15 and 30 days of feeding. These parameters were substantially enriched with a 10 mg/g diet (p < 0.05) of EPS and EPS-ZnO NPs in comparison with the control. Furthermore, the EPS and EPS-ZnO NP supplemental diet actively enhanced the antioxidant response (glutathione peroxidase, superoxide dismutase, and catalase). In addition, the supplemental diet of EPS and EPS-ZnO NPs lowered the death rate and improved the disease resistance of O. mossambicus following assessment with A. hydrophila and V. parahaemolyticus at 50 µL. Hence, the overall results suggest that the supplemental diet of EPS and EPS-ZnO NPs might be used to ensure aquaculture feed additives.

Biochemical, Genotoxic and Histological Implications of Polypropylene Microplastics on Freshwater Fish Oreochromis mossambicus: An Aquatic Eco-Toxicological Assessment

In recent years, polypropylene microplastic has persisted in freshwater ecosystems and biota, forming ever-growing threats. This research aimed to prepare polypropylene microplastics and evaluate their toxicity to the filter feeder Oreochromis mossambicus. In this research, fish were given a dietary supplement of polypropylene microplastics at 100, 500, and 1000 mg/kg for acute (96 h) and sub-acute (14 days) durations to assess toxic effects on liver tissues. FTIR results revealed the presence of polypropylene microplastic in their digestion matter. The ingestion of microplastics in O. mossambicus led to fluctuations in homeostasis, an upsurge in reactive oxygen species (ROS) levels, an alteration in antioxidant parameters, including superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST), and glutathione peroxidase (GPx); a promotion in the oxidation of lipid molecules; and a denaturation in the neurotransmitter enzyme acetylcholinesterase (AChE). Our data indicated that sustained exposure to microplastics (14 days) produced a more severe threat than acute exposure (96 h). In addition, higher apoptosis, DNA damage (genotoxicity), and histological changes were found in the liver tissues of the sub-acute (14 days) microplastics-treated groups. This research indicated that the constant ingestion of polypropylene microplastics is detrimental to freshwater environments and leads to ecological threats.

Hybrid of Metapenaeus dobsoni lectin and platinum nanoparticles exert antimicrobial and immunostimulatory effects to reduce bacterial bioburden in infected Nile tilapia

A novel antibacterial immunostimulant using Platinum nanoparticles (PtNPs) and lectin from Metapenaeus dobsoni (Md-Lec) was developed. The Md-Lec and PtNPs (Pt-lec) hybrid formed through non-covalent interaction exhibits antimicrobial activity against fish specific pathogens by affecting membrane integrity and producing excess reactive oxygen species. The therapeutic efficacy of Pt-lec was demonstrated through rescuing Aeromonas hydrophila infected Nile Tilapia. Pt-lec prevents the infection spreading and reduces the bacterial bioburden in less than 12 h, and as a result of this the fish were restored to normalcy. To assess immunostimulation, we studied the expression of three different immune related genes, namely LEC, Myd88 and COX-2 in the gills, liver, spleen and kidney of fish under various experimental conditions. Our results showed that Pt-lec treatment appeared to be better when compared to lectin alone in enhancing the expression of Myd88 and COX-2, but LEC was not as expected. These results suggest that Pt-lec has the ability to protect Nile Tilapia against bacterial infection by restricting bacterial bioburden through their direct effects on the bacterial membrane and indirectly through their effects on host immune-related gene expression. This hybrid could have potential “green” application in fish farming in rescuing infected animals when compared to widely and unregulated antibiotics.

Ingestion and impacts of water-borne polypropylene microplastics on Daphnia similis

Polypropylene microplastics are the leading contaminant in aquatic environments, although research on their toxicity remains scarce. The proposed research focuses on the harmful consequences of acute exposure to polypropylene microplastics in Daphnia similis. This work converts widely available polypropylene bags into microplastics using xylene. FTIR findings demonstrated the lack of xylene residue in the produced polypropylene microplastic particles, which were spherical and ranged in size from 11.86 to 44.62 µm (FE-SEM). The results indicate that acute exposure to polypropylene microplastics causes immobility in D. similis. Ingestion of microplastics enhances the generation of reactive oxygen species (ROS), as shown by biochemical studies. Due to the production of free radicals in D. similis, the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione-S-transferase (GST) and a non-antioxidant enzyme of reduced glutathione (GSH) and also oxidative stress effects in lipid (lipid peroxidation - LPO), protein (carbonyl protein - CP) were increased. Additionally, the amount of the neurotransmitter enzyme acetylcholinesterase (AChE) activity was decreased. These findings indicate that the accumulation of polypropylene microplastics in the bodies of filter-feeding organisms should aggravate toxicity in the freshwater environment.

Oral vaccination for sustainable disease prevention in aquaculture-an encapsulation approach

The prevalence of infectious diseases in the aquaculture industry and a limited number of safe and effective oral vaccines has imposed a challenge not only for fish immunity but also a threat to human health. The availability of fish oral vaccines has expanded recently, but little is known about how well they work and how they affect the immune system. The unsatisfactory efficacy of existing oral vaccinations is partly attributable to the antigen degradation in the adverse gastrointestinal environment of fishes, the highly tolerogenic gut environment, and inferior vaccine formulation. To overcome such challenges in designing: an easier, cost-efficient, and effective vaccination method, several encapsulation methods are being adopted to safeguard antigens from the intestinal atmosphere for their immunogenic functions. Oral vaccination is easily degraded by gastric acids and enzymes before reaching the immunological site; however, this issue can be solved by encapsulating antigens in poly-biodegradable nanoparticles, transgenic designed bacteria, plant systems, and live feeds. To enhance the immunological impact, each antigen delivery method operates at a different level. Utilizing nanotechnology, it has been possible to regulate vaccination parameters, target particular cells, and lower the antigen dosage with potent nanomaterials such as chitosan, poly D,L-lactic-co-glycolic acid (PLGA) as vaccine carriers. Live feeds such as Artemia salina can be utilized as bio-carrier, owing to their appropriate size and non-filter feed system, through a process called bio-encapsulation. It ensures the protection of antigens over the fish intestine and ensures complete uptake by immune cells in the hindgut for increased immune response. This review comprises recent advances in oral vaccination in aquaculture in terms of an encapsulation approach that can aid in future research.

Protective effects of dietary supplementation of probiotic Bacillus licheniformis Dahb1 against ammonia induced immunotoxicity and oxidative stress in Oreochromis mossambicus

The goal of this study was to assess the efficacy of probiotics in mitigating ammonia-induced toxicity in fish. Fish were divided into four groups: control, only probiotic, only ammonia, and combined ammonia + probiotic. For 8 weeks, the Oreochromis mossambicus were exposed to waterborne ammonia at 1.0 mg L^-1 and/or dietary Bacillus licheniformis Dahb1 at 10⁷ cfu g^-1. After the 4^th and 8^th weeks, the fish were evaluated for growth performance, enzymatic and non-enzymatic antioxidant activities (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) reduced glutathione (GSH), neurotoxicity (acetylcholinesterase - AChE), non-specific immune responses (lysozyme (LYZ), myeloperoxidase (MPO), reactive nitrogen and oxygen species (RNS and ROS) and oxidative stress effects (lipid peroxidation (LPO), DNA damage)). Our results showed that in the absence of waterborne ammonia exposure, B. licheniformis Dahb1 significantly improved growth performance, enzymatic and non-enzymatic antioxidant capacity, AChE activity, non-specific immune response and decreased oxidative stress effect. Ammonia exposure resulted in significantly lower growth performance, reduced enzymatic and non-enzymatic antioxidant ability, decreased AChE activity, decreased non-specific immune response and increased oxidative stress effect. When O. mossambicus were exposed to ammonia, supplementation with B. licheniformis Dahb1 in the diet significantly increased survival, indicating that it may have a significant protective effect against ammonia toxicity by enhancing enzymatic and non-enzymatic antioxidant ability, activity of AChE, non-specific immune response and reduced oxidative stress effect. According to our findings, diet supplementation of B. licheniformis Dahb1 (10⁷ cfu g^-1) has the potential to combat ammonia toxicity in O. mossambicus.

Comparative toxicity of silver nanoparticles and silver nitrate in freshwater fish Oreochromis mossambicus: A multi-biomarker approach

Silver nanoparticles (AgNPs) in the aquatic environment affect ecological repercussions and have fatal impacts on aquatic animals. The current study examined and correlated the toxicity of silver nitrate (AgNO₃) and silver nanoparticles (AgNPs) to the Mozambique tilapia, Oreochromis mossambicus. The comparative toxicity studies were done by exposing O. mossambicus to various doses of AgNO₃ and AgNPs (0, 25, 50, 75, and 100 μg/L) over a 7-day subacute exposure period. AAS analysis was used to detect Ag accumulation, while the histological examination established gill tissue damage. Oxidative stress affects lipid peroxidation (LPO) and protein carbonyl activity (PCA) in the gill tissue. Antioxidant parameters such as glutathione-S-transferase (GST), glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase activity (CAT), and non-enzymatic antioxidants such as metallothionein (MT) and reduced glutathione. The serum in the blood was used to determine non-specific immunological characteristics such as lysozyme (LYZ), myeloperoxidase (MPO), and respiratory burst activity (RBA). The neurotoxic impact of acetylcholine esterase activity (AChE) was investigated in brain tissues. The findings demonstrated that larger concentrations of AgNO₃ than AgNPs improved enzymatic antioxidant activities in the gill tissue. Histological examination of fish gills demonstrated that both AgNPs and AgNO₃ induced telangiectasia and epithelial cell hyperplasia. By increasing the concentration of AgNPs and AgNO₃, the present research demonstrated that silver accumulation leads to inefficient oxidative stress and altered enzymatic and non-enzymatic parameters, leading to cellular damage.

Dietary consumption of polypropylene microplastics alter the biochemical parameters and histological response in freshwater benthic mollusc Pomacea paludosa

One of the most common environmental pollutant in aquatic ecosystems are polypropylene microplastics and their impacts on aquatic organisms are still scarce. The study aimed to prepare polypropylene microplastics using organic solvent (spherical and 11.86-44.62 μm) and then test their toxicity on the freshwater benthic mollusc grazer Pomaceae paludosa. The present study investigated chronic (28 days) exposure of polypropylene microplastics via dietary supplements (250 mg kg^-1, 500 mg kg^-1 & 750 mg kg^-1) in P. paludosa, and the toxic effect was evaluated in digestive gland tissue. The FTIR results revealed no change in polypropylene microplastics during ingestion or after egestion. On the other hand, Ingestion causes accumulation in their bodies and disrupts redox homeostasis. Meanwhile, alteration occurs in oxidative stress-related biomarkers such as increased reactive oxygen species level (ROS), impaired the biochemical parameters of antioxidant system catalase (CAT), glutathione peroxidase (GPx), reduced glutathione (GSH), and glutathione - S- transferase (GST), deterioration of oxidative stress effects in lipid peroxidation (LPO) and carbonyl protein (CP) and changed the digestive enzymes such as amylase, pepsin, esterase and alkaline phosphatase that are measured in hepatopancreas tissue. The histology results revealed that ingesting these microplastics caused severe damage to the digestive gland cells. According to the findings, ingestion of polypropylene microplastics in benthic freshwater mollusc causes more serious harm and impacts energy acquisition. This finding represents the ecological risk of polypropylene microplastic pollution in the freshwater ecosystem.

Swift synthesis of zinc oxide nanoparticles using unripe fruit extract of Pergularia daemia: An enhanced and eco-friendly control agent against Zika virus vector Aedes aegypti

In this study Pergularia daemia unripe fruits were used to synthesize zinc oxide nanoparticles (Pd-ZnONPs). UV-vis Spectroscopy detected the production of ZnONPs. XRD, FTIR, SEM, and TEM studies were used to characterize the synthesized Pd-ZnONPs. Aedes aegypti (Ae. aegypti) third instar larvae were analyzed to diverse concentrations of Pd-unripe fruit extract and Pd-ZnONPs for 24 hours to assess the larvicidal effect. Mortality was also detected in Ae. aegypti larvae under laboratory conditions, with corresponding LC₅₀ and LC₉₀ values of 11.11 and 21.20 µg/ml respectively. As a result of this study, the levels of total proteins, esterases, acetylcholine esterase, and phosphatase enzymes in the third instar larvae of Ae. aegypti were significantly lower than the control. These findings suggest that Pd-ZnONPs could be used to suppress mosquito larval populations.

Synthesis and physicochemical characteristics of Ag-doped hydroxyapatite nanoparticles, and their potential biomedical applications

In this present scenario, hydroxyapatite (HAp) nanostructures were synthesized through green routes for biomedical applications, particularly remediation towards human pathogens and cancer cells. The present study aims at forming non-toxic and eco-friendly silver (Ag⁺) doped HAp using Polyethylene glycol (PEG), Cetyl Trimethyl ammonium bromide (CTAB) and curcumin. Ag⁺ doped HAp nanoparticles (NPs) were prepared by the sol-gel method with a cube and rod-like morphology. Ag-HApNPs showed a sharp and well-defined diffraction peak, which possesses the hexagonal crystalline structure with space group P6₃/m. The Fourier-transform infrared spectroscopy and Raman spectra confirmed the formation of Ag-HApNPs, and the bandgap values were obtained using UV-DRS analysis. The Ag-HApNPs with PEG, CTAB and curcumin might be fabricated materials were examined against antibacterial, antifungal, antioxidant, and cytotoxic activities, which provided exemplary biomedical applications. Overall, Ag-HApNPs can be used as potential drug delivery and perspectives to control multidrug-resistant pathogens.

Evaluating the structural and immune mechanism of Interleukin-6 for the investigation of goat milk peptides as potential treatments for COVID-19

The function of Immune control, haematopoiesis, and inflammation all depend on the cytokine Interleukin 6 (IL-6), and higher expression of IL-6 is seen in COVID-19 and other diseases. The immune protein IL-6 activation is dependent on binding interactions with IL-6Rα, mIL-6R, and sIL-6R for its cellular function. Termination of these reaction could benefit for controlling the over-expression in COVID-19 patients and that may arise as inhibitors for controlling COVID-19. Traditionally, the goat milk has been prescribed as medicine in ayurvedic practice and through this work, we have explored the benefits of peptides from goat milk as IL-6 inhibitors, and it have the potential of inhibiting the over expression of IL-6 and control the COVID-19 disease. Computational experiments have shown that goat peptides had strong interactions with IL-6, with higher scoring profiles and energy efficiency ranging from −6.00 kcal/mol to −9.00 kcal/mol in docking score and −39.00 kcal/mol in binding energy. Especially the YLGYLEQLLR, VLVLDTDYK and AMKPWIQPK peptides from goat milk holds better scoring and shows strong interactions were identified as the most potential IL-6 inhibitor candidates in this study. Peptides from Goat proteins, which are capable of binding to the IL-6 receptor with strong binding conformations, have no negative effects on other immune system proteins.

Toxicity evaluation of polypropylene microplastic on marine microcrustacean Artemia salina: An analysis of implications and vulnerability

Polypropylene microplastic particles are one of the predominant pollutants in marine ecosystems and their toxic effects are unknown in aquatic biota. The study aims to prepare the spherical shaped polypropylene microplastics (size range 11.86 μm-44.62 μm) and assess their toxic effects (1, 25, 50, 75 and 100 μg/mL) in various life stages (nauplii, metanauplii and juvenile) of marine microcrustacean Artemia salina within 48 h. In addition, microplastics ingestion by Artemia nauplii was proved by FTIR analysis. The results revealed, microplastics accumulation in their tract leads to change in their homeostasis, as followed increase in the oxidative burst causes mortality in nauplii (LC₅₀ 40.947 μg/mL) and meta nauplii (LC₅₀ 51.954 μg/mL). In juvenile, swimming behaviour was changed. Moreover, microplastic consumption disturbs the antioxidant biomarkers such as superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), glutathione -S- Transferase (GST) and reduces the neurotransmitter enzyme acetylcholinesterase (AChE) activity. In addition, histology of juvenile Artemia showed damage in epithelial cells. This study indicates that exposure to polypropylene microplastics is more harmful to zooplanktonic organisms of the marine ecosystem.

Synthesis and characterization of cry protein coated zinc oxide nanocomposites and its assessment against bacterial biofilm and mosquito vectors

Mosquitoes need to be eradicated as they can spread deadly diseases. Cry toxic proteins from Bacillus and zinc oxide nanoparticles also can tremendously control pest and bacterial pathogens. With this reference, the Ac-ZnO NPs was effectively synthesized using Acorus calamus rhizomes extract where after incorporated with bacterial cry toxic protein (Btp) to produce Btp-Ac-ZnO nanocomposites. The XRD and FTIR, disclose the crystalline form with an average size of 17.47 nm and the possible biomolecules of Btp-Ac-ZnO NCs. SEM and TEM make known the well agglomerated and cone shape of Btp-Ac-ZnO NCs. The NCs show concentration-dependent antioxidant activity. Btp-Ac-ZnO NCs drastically arrest the formation of biofilm by the pathogenic bacteria such as E. faecalis, S. aureus, P. aeruginosa, and P. vulgaris at 100 μg/mL. All the above, the Btp-Ac-ZnO NCs exhibits superior larvicidal activity against three mosquito vectors namely Ae. aegypti, An. stephensi and Cx. quinquefasciatus with LC₅₀ values of 43.76, 39.60 and 37.13 μg/mL respectively. Besides, the biological enzymes are significantly reduced in the treated larvae than that of untreated one, which indicates the effect of Btp-Ac-ZnO NCs. Since, the Btp-Ac-ZnO NCs could be utilized against the pathogenic bacteria, and its biofilm structure, and also in the vector control sectors.

Comparative evaluation on the toxic effect of silver (Ag) and zinc oxide (ZnO) nanoparticles on different trophic levels in aquatic ecosystems-A review

Silver (Ag) and zinc oxide (ZnO) are considered to be harmful nanoparticles (NPs) to the aquatic organisms as their intake causes toxic impacts to wildlife, through direct ingestion or by the transference along trophic levels. Over usage and ultimate disposal of metallic particles from the industries subsequently lead to pollution of the aquatic environment. Exposure of NPs in aquatic ecosystem alters biological and physicochemical parameters of the water and aquatic organisms and determine their potential ecotoxicological impacts. Prolonged exposure of aquatic organisms to these NPs results in differential bioaccumulation and distribution into internal organs like liver, kidney, gills, brain and muscle tissue. The contact of NPs to aquatic organisms induces various types of toxic traits including cytotoxicity, genotoxicity and epigeneticity. Taking this in consideration this present review focus on the comparative impact of ZnO and Ag nanoparticles towards both vertebrates and invertebrates in aquatic ecosystems.

Molecular interaction analysis of β-1, 3 glucan binding protein with Bacillus licheniformis and evaluation of its immunostimulant property in Oreochromis mossambicus

Analyzing the health benefits of any two immunostimulants (synbiotics) in combined form and information on their interactions gain more visibility in the usage of synbiotics in aquafarms. With this intention, the current work explores the immunostimulant effect and structural interaction of synbiotic (β-1, 3 glucan binding protein from marine crab, Portunus pelagicus (Ppβ-GBP) and Bacillus licheniformis) on Oreochromis mossambicus. The experimental diet was prepared with Ppβ-GBP and B. licheniformis, and nourished to the fingerlings of O. mossambicus for 30 days. After the experimental trial, a higher growth rate and immune reactions (lysozyme, protease, myeloperoxidase and alkaline phosphatase activity) were noticed in the fish nourished with synbiotic (B. licheniformis and Ppβ-GBP) enriched diet. Moreover, the synbiotic enriched diet elevated the antioxidant responses like glutathione peroxidase (GSH-Px) and catalase (CAT) activity in the experimental diet-nurtured fish. At the end of the feed trial, synbiotic diet nourished fish shows an increased survival rate during Aeromonas hydrophila infection, reflecting the disease resistance potential of experimental fish. Also, the interaction between Ppβ-GBP and Bacillus licheniformis was analyzed through computational approaches. The results evidenced that, Ppβ-GBP interacts with the B. licheniformis through sugar-based ligand, β-glucan through a hydrogen bond with a good docking score. Thus, the synbiotic diet would be an effective immunostimulant to strengthen the fish immune system for better productivity.

The dietary supplementation of zinc oxide and selenium nanoparticles enhance the immune response in freshwater fish Oreochromis mossambicus against aquatic pathogen Aeromonas hydrophila

BACKGROUND

Green nanoparticles are subjected as an immunostimulant against bacterial pathogens.

METHODS

Murraya koenigii berry extract-based synthesized zinc oxide nanoparticles (Mb-ZnO NPs) and selenium nanoparticles (Mb-Se NPs) were relatively analyzed for immunostimulation in serum and mucus fish Oreochromis mossambicus against Aeromonas hydrophila infections. Initial minimum inhibitory concentration (MIC) was determined for both Mb-ZnO NPs and Mb-Se NPs followed by specific growth rate (SGR), antioxidant level (Superoxide dismutase activity (SOD), Catalase activity (CA), and Glutathione peroxidase activity (GPx)), and immune parameters Myeloperoxidase activity (MPO), Respiratory burst activity (RBA), Lysozyme activity (LYZ), Alkaline phosphatase activity (ALP), Serum antiprotease activity and Natural complement activity (NAC).

RESULTS

The potential bacterial inhibition property of Mb-ZnO NPs and Mb-Se NPs exhibited the most negligible concentration of 25 and 15 μg mL^-1, respectively, against A. hydrophila. In addition, Mb-ZnO NPs and Mb-Se NPs exhibited 70-80 % and 90-95 % diminished biofilm activity at 50 μg mL^-1 that was viewed under an inverted research microscope and confocal laser scanning microscopy (CLSM). Protein leakage and nucleic acid leakage assay quantified oozed out protein and nucleic acid from A. hydrophila that confirms Mb-Se NPs exhibited vigorous antibacterial activity than Mb-ZnO NPs at tested concentrations. Oreochromis mossambicus fed with Mb-ZnO NPs and Mb-Se NPs supplemented diet at different concentrations (0.5 mg/kg, 1 mg/kg and 2 mg/kg) improved SGR along with a rise in the immune response of those fishes against A. hydrophila infection. Serum and mucus of fish fed with Mb-Se NPs supplemented diet exhibited a significant rise in antioxidant level SOD, CA and GPx at a dosage of 2 mg/kg. Likewise, lipid peroxidation assay detected significantly diminished oxidative stress in the serum and mucus of fish fed with Mb-Se NPs supplemented diet (2 mg/kg). Enhanced immune parameters in serum and mucus of fish fed with Mb-Se NPs supplemented diet determined by MPO, RBA, LYZ, ALP, Serum antiprotease activity and NAC.

CONCLUSION

Thus O. mossambicus fed with Mb-Se NPs supplemented diet was less prone to become infected by aquatic pathogen A. hydrophila established by challenge study. On the whole, Mb-Se NPs supplemented diet ensured the rise in antioxidant response that boosts the immune responses and reduces the chance of getting infected against A. hydrophila infections.

β-1,3-Glucan binding protein-based silver nanoparticles enhance the wound healing potential and disease resistance in Oreochromis mossambicus against Aeromonas hydrophilla

Here we attempted to synthesize β-1,3-glucan binding protein-based silver nanoparticles (Phβ-GBP-AgNPs) and evaluate its wound healing and disease resistance prompting ability in Oreochromis mossambicus. Using a column chromatography technique, an immune molecule, Phβ-GBP was purified from the haemolymph of rice field crab, Paratelphusa hydrodromus. Phβ-GBP-AgNPs were synthesized and described through SDS-PAGE, UV-vis spectroscopy, HR-TEM, XRD and FTIR analysis. HR-TEM revealed that the synthesized Phβ-GBP-AgNPs were spherical with a 20-40 nm size range and the particles were not aggregated. Wound and infection were experimentally generated in O. mossambicus and treated with Phβ-GBP, chem-AgNPs and Phβ-GBP-AgNPs for 20 days. The immune parameters (peroxidase, lysozyme and protease) and antioxidant enzymes (SOD and catalase) were examined in the serum of experimental fish. Phβ-GBP-AgNPs elevated the immune and antioxidant enzymes during the healing process and enhanced the wound healing percentage in fish than Phβ-GBP and chem-AgNPs. The immune parameters and antioxidant enzymes were declined in the serum of fish (treated with Phβ-GBP-AgNPs) after the mid-period of wound healing. Compared to others, relative percentage survival was increased in experimentally wounded and infected fish treated with Phβ-GBP-AgNPs against Aeromonas hydrophila. Moreover, Phβ-GBP-AgNPs exhibited less toxicity towards Artemia salina than chem-AgNPs during 24 h exposure period. As a result, Phβ-GBP-AgNPs may act as an alternative to commercial antibiotics and be considered an effective immunostimulant in treating skin lesions in intensive farming.

SARS-CoV-2 spike protein: Site-specific breakpoints for the development of COVID-19 vaccines

SARS-CoV2 is a member of human coronaviruses and is the causative agent of the present pandemic COVID-19 virus. In order to control COVID-19, studies on viral structure and mechanism of infectivity and pathogenicity are sorely needed. The spike (S) protein is comprised of S1 & S2 subunits. These spike protein subunits enable viral attachment by binding to the host cell via ACE-2 (angiotensin converting enzyme-2) receptor, thus facilitating the infection. During viral entry, one of the key steps is the cleavage of the S1-S2 spike protein subunits via surface TMPRSS2 (transmembrane protease serine 2) and results in viral infection. Hence, the S-protein is critical for the viral attachment and penetration into the host. The rapid advancement of our knowledge on the structural and functional aspects of the spike protein could lead to development of numerous candidate vaccines against SARS-CoV2. Here the authors discuss about the structure of spike protein and explore its related functions. Our aim is to provide a better understanding that may aid in fighting against CoVID-19 and its treatment.

Interactive effects of freshwater acidification and selenium pollution on biochemical changes and neurotoxicity in Oreochromis mossambicus

Effect of selenium and acidification in freshwater environment was assessed solitary but no reports are available on the impacts of both factors act together. In the present study, effects of combined simultaneous exposure to selenium (Se) and low pH were assessed in Mozambique tilapia, Oreochromis mossambicus. Responses were measured based on antioxidant defenses (enzymatic SOD, CAT, GPx and non-enzymatic GSH), biotransformation enzyme (GST), metallothionein levels (MT), oxidative damage (LPO, CP), Na⁺/K⁺-ATPase (NKA) activity in gills and liver tissues and neurotoxicity (acetylcholinesterase, AChE) response in brain tissue. Fish were exposed to combined treatment at different pH levels (7.5, control (optimum pH for tilapia growth); 5.5, low pH) and Se concentrations (0, 10, and 100 μg L^-1). Toxicity levels of Se were not significantly different under control and low pH indicating that pH did not affect Se toxicity. Levels of GSH and MT were enhanced in Se-exposed fish at both pH. Combined effects of high Se concentration and low pH decreased SOD and CAT activities and increased those of GPx and GST. However, organisms were not able to prevent cellular damage (LPO and CP), indicating a condition of oxidative stress. Furthermore, inhibition of Na⁺/K⁺-ATPase activity was showed. Additionally, neurotoxicity effect was observed by inhibition of cholinesterase activity in organisms exposed to Se at both pH conditions. As a result, the combined stress of selenium and freshwater acidification has a slight impact on antioxidant defense mechanisms while significantly inhibiting cholinesterase and Na+/K + -ATPase activity in fish. The mechanisms of freshwater acidification mediating the toxic effects of trace non-metal element on freshwater fish need to investigate further.

Bio-Fabrication of Human Amniotic Membrane Zinc Oxide Nanoparticles and the Wet/Dry HAM Dressing Membrane for Wound Healing

The preparation of unique wet and dry wound dressing products derived from unprocessed human amniotic membrane (UP-HAM) is described. The UP-HAM was decellularized, and the constituent proteins were cross-linked and stabilized before being trimmed and packed in sterile Nucril-coated laminated aluminium foil pouches with isopropyl alcohol to manufacture processed wet human amniotic membrane (PW-HAM). The dry type of PD-HAM was prepared by decellularizing the membrane, UV irradiating it, lyophilizing/freeze-drying it, sterilizing it, and storing it at room temperature. The UP-HAM consists of a translucent yellowish mass of flexible membranes with an average thickness of 42 μm. PW-HAM wound dressings that had been processed, decellularized, and dehydrated had a thinner average thickness of 30 μm and lacked nuclear-cellular structures. Following successful decellularization, discrete bundle of fibrous components in the stromal spongy layers, microvilli and reticular ridges were still evident on the surface of the processed HAM, possibly representing the location of the cells that had been removed by the decellularization process. Both wet and dry HAM wound dressings are durable, portable, have a shelf life of 3–5 years, and are available all year. A slice of HAM dressing costs 1.0 US$/cm². Automation and large-scale HAM membrane preparation, as well as storage and transportation of the dressings, can all help to establish advanced technologies, improve the efficiency of membrane production, and reduce costs. Successful treatment of wounds to the cornea of the eye was achieved with the application of the HAM wound dressings. The HAM protein analysis revealed 360 μg proteins per gram of tissue, divided into three main fractions with MWs of 100 kDa, 70 kDa, and 14 kDa, as well as seven minor proteins, with the 14 kDa protein displaying antibacterial properties against human pathogenic bacteria. A wide range of antibacterial activity was observed after treatment with 75 μg/ml zinc oxide nanoparticles derived from human amniotic membrane proteins (HAMP-ZnO NP), including dose-dependent biofilm inhibition and inhibition of Gram-positive (S. aureus, S. mutans, E. faecalis, and L. fusiformis) and Gram-negative bacteria (S. sonnei, P. aeruginosa, P. vulgaris, and C. freundii).

Purification and partial characterization of carbohydrate-recognition protein C-type lectin from Hemifusus pugilinus

A mannose binding lectin (C-type lectin) was detected in a molluscan snail Hemifusus pugilinus, this lectin molecule was isolated and purified from the plasma using mannose-fixed sepharose CL-4B column affinity chromatography. The purified protein corresponds to the molecular weight of 118 kDa on an SDS-PAGE gel. The divalent cation-dependent nature of the H. pugilinus lectin (Hp-Lec) evidenced through pH and thermal stability analysis using Circular Dichroism (CD) and Surface Plasmon Resonance (SPR) respectively. Functional investigations of the Hp-Lec reveal a broad spectrum of bacterial agglutination activity against wide range of Gram-positive and Gram-negative bacterial strains. Furthermore, Hp-Lec displayed the haemo agglutination activity against vertebrate red blood cells (RBCs) and its titers were recorded. Excitingly, microbial virulent pathogens such as fungal strains tested against the purified Hp-Lec (25 and 50 μg/ml), which exhibits the effective antifungal activity against tested fungal pathogens such as Aspergillus niger and A. flavus.

Antibiofilm and immunological properties of lectin purified from shrimp Penaeus semisulcatus

Penaeid prawns are considered as most demanding fishery resources. The current study aims to purify and characterize lectin from the haemolymph of Penaeus semisulcatus. The semisulcatus-lectin was purified by affinity chromatography using mannose coupled Sepharose CL-4B column and purified lectin exhibited a single band of 66 kDa in SDS-PAGE. The purity and crystalline structure of purified lectin was confirmed by HPLC and X-ray diffraction analysis. Semisulcatus-lectin exhibited yeast agglutination activity against Saccharomyces cerevisiae and agglutinated human erythrocytes. Semisulcatus-lectin was evaluated for phenol oxidase activation and phagocytic activities. It was observed that semisulcatus-lectin had antibacterial activity against Gram-negative Vibrio parahaemolyticus and Aeromonas hydrophila, suggesting a potential therapeutic strategy in aquaculture industry for disease management.

South Indian medicinal plants can combat deadly viruses along with COVID-19? - A review

SARS-CoV-2 is a causative agent of Coronavirus disease-19 (COVID-19), which is considered as a fatal disease for public health apprehension worldwide. This pathogenic virus can present everywhere. As it is a virus it can extend easily and cause severe illness to humans. Hence, an efficient international attentiveness of plan is necessary to cure and prevent. In this review, epidemic outbreak, clinical findings, prevention recommendations of COVID-19 and suggestive medicinal value of south Indian plant sources have been discussed. Though the varieties of improved approaches have been taken in scientific and medicinal concern, we have to pay attention to the medicinal value of the plant-based sources to prevent these types of pandemic diseases. This is one of the suggestive and effective ways to control the spreading of viruses. In the future, it is required to provide medicinal plant-based clinical products (Masks, sanitizers, soap, etc.,) with better techniques by clinicians to contend the scarcity and expose towards the nature-based medicine rather than chemical drugs. This may be a benchmark for the economical clinical trials of specific plant material to treat the viral diseases in the future.

Photocatalytic, antiproliferative and antimicrobial properties of copper nanoparticles synthesized using Manilkara zapota leaf extract: A photodynamic approach

Copper nanoparticles were synthesized using Manilkara zapota leaf extract. The synthesis of the nanoparticle was primarily visualized when the colour of the reaction mixture turned into reddish-brown. Biosynthesized nanoparticles were characterized by UV-vis, FT-IR, XRD, SEM and EDX. The UV spectra showed maximum absorption at 584 nm. FT-IR studies showed stretching frequency at 592.76 cm^-1, which is the fingerprint region for Cu-O bond. The crystallinity of the synthesized copper nanoparticles (Mz-Cu NPs) was revealed through XRD analysis. The synthesized Mz-Cu NPs were spherical with an average size of 18.9-42.5 nm and it was shown by SEM analysis. EDX analysis displayed that the nano sample contains 58 % of copper. The antimicrobial property of the synthesized nanoparticles was evaluated against fungal plant pathogens Rhizoctonia solani (MTCC 12232), Sclerotium oryzae (MTCC 12230) and bacterial species, namely Bacillus subtilis (ATCC 23857), Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 25923), Vibrio harveyi (ATCC 35084), Vibrio parahaemolyticus (ATCC 33845). In in-vitro haemolytic assay, the particle showed 5.73, 3.34, 0.5 % hemolysis at 100, 50, 25 μg/mL concentration respectively. In the antiproliferative assay, the IC₅₀ values of MCF7 and Vero cells were found to be 53.89 and 883.69 μg/μl. The particle degraded Methyl violet, Malachite green and Coomassie brilliant blue by 92.2, 94.9 and 78.8 %, within 50, 40 and 60 min, respectively, through its photocatalytic activity.

High synergistic antibacterial, antibiofilm, antidiabetic and antimetabolic activity of Withania somnifera leaf extract-assisted zinc oxide nanoparticle

Nanotechnology is currently gaining immense attention to combat food borne bacteria, and biofilm. Diabetes is a common metabolic disease affecting majority of people. A better therapy relies on phytomediated nanoparticle synthesis. In this study, W. somnifera leaf extract-assisted ZnO NPs (Ws-ZnO NPs) was synthesized and characterized. From HR-TEM analysis, it has been found that the hexagonal wurtzite particle is 15.6 nm in size and - 12.14 mV of zeta potential. A greater antibacterial effect of Ws-ZnO NPs was noticed against E. faecalis and S. aureus at 100 µg mL^-1. Also, the biofilm of E. faecalis and S. aureus was greatly inhibited at 100 µg mL^-1 compared to E. coli and P. aeruginosa. The activity of α-amylase and α-glucosidase enzyme was inhibited at 100 µg mL^-1 demonstrating its antidiabetic potential. The larval and pupal development was delayed at 25 µg mL^-1 of Ws-ZnO NPs. A complete mortality (100%) was recorded at 25 µg mL^-1. Ws-ZnO NPs showed least LC₅₀ value (9.65 µg mL^-1) compared to the uncoated ZnO NPs (38.8 µg mL^-1) and leaf extract (13.06 µg mL^-1). Therefore, it is concluded that Ws-ZnO NPs are promising to be used as effective antimicrobials, antidiabetic and insecticides to combat storage pests.

Immunological and antibiofilm property of haemocyanin purified from grooved tiger shrimp (Penaeus semisulcatus): An in vitro and in silico approach

Haemocyanin (Hc) is a non-specific innate immune protein present in the haemolymph of arthropods and molluscs. In the current study, we characterized the structural and immunological properties of Hc from grooved tiger shrimp, Penaeus semisulcatus. Hc was isolated from the haemolymph of P. semisulcatus by gel filtration column chromatography using Sephadex G-100. High-performance liquid chromatography of the purified Hc emerged as a single peak through a retention time of 3.3 min demonstrating the homogeneity nature of the protein. X-ray diffraction analysis revealed a distinct peak at 31.7° indicating the crystalline character of the purified Hc. Circular dichroism spectra of the purified Hc displayed negative ellipticity bands close to 225 nm and 208 nm representing β-sheet secondary structure. The purified Hc agglutinated sheep RBCs, yeast Saccharomyces cerevisiae and fungal Candida albicans. In addition, the purified Hc displayed antibacterial activity against Gram-positive bacteria (Bacillus thuringiensis and Bacillus pumilis) and Gram-negative bacteria (Vibrio parahaemolyticus and Vibrio alginolyticus) with a minimal inhibitory concentration of 50 μg/ml. Antibiofilm activity revealed the potential of purified Hc to inhibit biofilm formation of both Gram-positive and Gram-negative bacterial pathogens. Furthermore, live/dead staining of biofilms demonstrated the reduced viability of bacterial cells after exposure to the purified Hc. In silico molecular modeling was carried out using the sequence of Hc from SwissProt and molecular docking was performed with the cell surface components found in Gram-positive and Gram-negative bacteria. Overall our study demonstrates the involvement of Hc in the native immune reaction of P. semisulcatus by eliciting pathogen recognition. Thus, Hc could enhance disease resistance against pathogenic infection in shrimp aquaculture.

High synergistic antibacterial, antibiofilm, antidiabetic and antimetabolic activity of Withania somnifera leaf extract-assisted zinc oxide nanoparticle

Nanotechnology is currently gaining immense attention to combat food borne bacteria, and biofilm. Diabetes is a common metabolic disease affecting majority of people. A better therapy relies on phytomediated nanoparticle synthesis. In this study, W. somnifera leaf extract-assisted ZnO NPs (Ws-ZnO NPs) was synthesized and characterized. From HR-TEM analysis, it has been found that the hexagonal wurtzite particle is 15.6 nm in size and - 12.14 mV of zeta potential. A greater antibacterial effect of Ws-ZnO NPs was noticed against E. faecalis and S. aureus at 100 µg mL^-1. Also, the biofilm of E. faecalis and S. aureus was greatly inhibited at 100 µg mL^-1 compared to E. coli and P. aeruginosa. The activity of α-amylase and α-glucosidase enzyme was inhibited at 100 µg mL^-1 demonstrating its antidiabetic potential. The larval and pupal development was delayed at 25 µg mL^-1 of Ws-ZnO NPs. A complete mortality (100%) was recorded at 25 µg mL^-1. Ws-ZnO NPs showed least LC₅₀ value (9.65 µg mL^-1) compared to the uncoated ZnO NPs (38.8 µg mL^-1) and leaf extract (13.06 µg mL^-1). Therefore, it is concluded that Ws-ZnO NPs are promising to be used as effective antimicrobials, antidiabetic and insecticides to combat storage pests.

Anti-biofilm properties and immunological response of an immune molecule lectin isolated from shrimp Metapenaeus monoceros

The study is carried out to understand the antimicrobial and immunological response of a potential immune molecule lectin, MmLec isolated from haemolymph of Speckled shrimp, Metapenaeus monoceros. MmLec was purified using mannose coupled Sepharose CL-4B affinity chromatography, which was further subjected on SDS-PAGE to ascertain the distribution of their molecular weight. Sugar binding specificity assay was conducted at various pH and temperatures to investigate the binding affinity of MmLec towards the specific carbohydrate molecule. Functional analysis of immune molecule MmLec included haemagglutination assays performed using human erythrocytes and yeast agglutination activity against Saccharomyces cerevisiae which, were analyzed using light microscopy. In order to study the antimicrobial activity, two Gram-negative (Vibrio parahaemolyticus and Aeromonas hydrophila) and two Gram-positive (Staphylococcus aureus and Enterococcus faecalis) bacteria were treated with purified MmLec. Moreover, these bacterial species were also treated at different concentration of the MmLec to speculate the antibiofilm properties of MmLec which was analyzed under Light Microscopy and Confocal Laser Scanning Microscopy. In addition, other functional characterization of MmLec showed the uniqueness of MmLec in agglutination of human erythrocyte as well as the cells of yeast Saccharomyces cerevisiae. Also, the phenoloxidase activity and encapsulation assay was evaluated. MTT assay displayed that MmLec are potent in anticancer activity. The study will help to understand the immunological interference and antimicrobial nature of MmLec which would be supportive in establishing a potential therapeutic tool and to develop better and novel disease control strategies in shrimp and farmed aquaculture industries as well as in health management.

Synthesis and characterization of crustin capped titanium dioxide nanoparticles: Photocatalytic, antibacterial, antifungal and insecticidal activities

Current scenario of bio-nanotechnology, successfully fabrication of ultrafine titanium dioxide nanoparticles (TiO₂NPs) using various biological protein sources for the multipurpose targets. The present research report involves synthesis of TiO₂NPs using antimicrobial peptide (AMP) crustin (Cr). Crustin previously purified from the blue crab, Portunus pelagicus haemolymph, by blue Sepharose CL-6B matrix assisted affinity column chromatography. Synthesized Cr-TiO₂NPs was physico-chemically characterized by UV-Visible spectroscopy (UV-Visible), X-ray Diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), High-resolution transmission electron microscopy (HR-TEM) and zeta potential examination. X-ray diffraction analysis for crystalline nature and phase identification of titanium dioxide nanoparticles was absorbed. Functional groups were found through FTIR ranges between 1620 and 1700 cm^-1. HR-TEM analysis showed that the synthesized Cr-TiO₂NPs tetragonal shape and sizes ranging from 10 to 50 nm. Finally, the surface charge of the Cr-TiO₂NPs was confirmed through zeta potential analysis. Furthermore, the characterized Cr-TiO₂NPs exhibited good biofilm inhibition against GPB - S. mutans (Gram Positive Bacteria- Streptococcus mutans), GNB - P. vulgaris (Gram Negative Bacteria- Proteus vulgaris) and fungal Candida albicans. Moreover, photocatalysis demonstrated that the Cr-TiO₂NPs was effectively explored the degradation of dyes. The results suggest that Cr-TiO₂NPs is an excellent bactericidal, fungicidal and photocatalytic agent that can be supportively used for biomedical and industrial applications.

Chronic exposure of Oreochromis niloticus to sub-lethal copper concentrations: Effects on growth, antioxidant, non-enzymatic antioxidant, oxidative stress and non-specific immune responses

BACKGROUND

Trace elements of copper (Cu) are one of the main forms of ecological noxious waste in freshwater systems that affect the survival and development of organisms. The objective of the current study was to investigate the effects of chronic exposure to Cu on the growth, oxidative stress, immune and biochemical response in the Nile tilapia, Oreochromis niloticus.

METHODS

Three groups of O. niloticus were tested as follows; the first group was used as the control (not treated with Cu in water), while the 2nd and 3rd groups were exposed to (low) 40 μg L^-1 and (high) 400 μg L^-1 concentrations of Cu added to water, respectively. The duration of the experiment, which was conducted in triplicate, was 60 d. End points were evaluated on days 30 and 60. Following 30 d and 60 d of exposure to Cu, the fish were removed from experimental tanks to determine growth. Consequently, blood samples were collected from caudal veins at the end of the trial period (30 d and 60 d) and serum was separated to evaluate different immunological parameters, such as lysozymes (LYZ), respiratory burst activity (RBA) and myeloperoxidase (MPO). Gill and liver tissues were collected for evaluation of Cu and certain biochemical parameters as follows: antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione-S-transferase (GST); non-enzymatic antioxidants such as glutathione (GSH) and metallothionein (MT), and oxidative stress indicators such as malondialdehyde (MDA) and protein carbonyl (PCO). The results pertaining to treatments and the control were compared using two-way ANOVA and Tukey's HSD test. The level of significance was set at P ≤ 0.05. Data were expressed as mean ± SD.

RESULTS

Chronic exposure to Cu did not induce any mortality in fish during the test period. However, following exposure to Cu, growth of fish in the exposed groups was affected more than that in the control group (unexposed to Cu). In addition, accumulation of Cu in the liver tissue was higher than that in the gill tissues of fish exposed to Cu, compared to that in the control. Gill and liver tissues of Cu-exposed fish showed a significant (P ≤ 0.05) reduction in the activities of the antioxidant enzymes, SOD, CAT, GPx, and GST, compared to those of unexposed fish. Non-enzymatic antioxidants, GSH and MT, in gill and liver tissues were significantly increased (P ≤ 0.05) in fish exposed to both concentrations of Cu, compared to those in unexposed fish. Oxidative stress indicators, MDA and PCO in gills and liver of Cu-exposed fish was significantly (P ≤ 0.05) at both tested concentrations, when compared to control group. Non-specific immune response of LYZ, RBA, and MPO activity in serum decreased significantly (P ≤ 0.05) in Cu-exposed fish, compared with that of unexposed fish.

CONCLUSION

Overall, the present results highlighted that chronic exposure to Cu ions may exert a strong effect on the antioxidant and immune responses of O. niloticus. Changes in antioxidant enzymes, oxidative stress effects and immune parameters during post-chronic metal exposure may indicate the potential of these parameters as biomarkers of metal toxicity in aquatic ecosystems.