Protective Effects of Dietary Garlic Powder Against Cadmium-induced Toxicity in Sea Bass Liver: a Chemical, Biochemical, and Transcriptomic Approach

Melatonin as an Ameliorative Agent Against Cadmium- and Lead-Induced Toxicity in Fish: an Overview

Diverse anthropogenic activities and lack of knowledge on its consequences have promoted serious heavy metal contaminations in different aquatic systems throughout the globe. The non-biodegradable nature of most of these toxic heavy metals has increased the concern on their possible bioaccumulation in aquatic organisms as well as in other vertebrates. Among these aquatic species, fish are most sensitive to such contaminated water that not only decreases their chance of survivability in the nature but also increases the probability of biomagnifications of these heavy metals in higher order food chain. After entering the fish body, heavy metals induce detrimental changes in different vital organs by impairing multiple physiological and biochemical pathways that are essential for the species. Such alterations may include tissue damage, induction of oxidative stress, immune-suppression, endocrine disorders, uncontrolled cell proliferation, DNA damage, and even apoptosis. Although uncountable reports have explored the toxic effects of different heavy metals in diverse fish species, but surprisingly, only a few attempts have been made to ameliorate such toxic effects. Since, oxidative stress seems to be the underlying common factor in such heavy metal-induced toxicity, therefore, a potent and endogenous antioxidant with no side effect may be an appropriate therapeutic solution. Apart from summarizing the toxic effects of two important toxicants, i.e., cadmium and lead in fish, the novelty of the present treatise lies in its arguments in favor of using melatonin, an endogenous free radical scavenger and indirect antioxidant, in ameliorating the toxic effects of heavy metals in any fish species.

Effect of garlic (Allium sativum) extract on growth, enzymological and biochemical responses and immune-related gene expressions in giant freshwater prawn (Macrobrachium rosenbergii)

In the current study, growth performance, biochemical constituents of muscle, activities of enzymes in the haemolymph, and expressions of immune-related genes were evaluated in the giant freshwater prawns Macrobrachium rosenbergii fed diets supplemented with aqueous garlic (Allium sativum) extract at 0, 5, 10 and 20 g/kg (w/w) for 60 days. At the end of the feeding trial, weight gain and specific growth rate were significantly improved in garlic-fed prawn groups compared with the control (p < 0.05). Moreover, feed conversion ratio was significantly lower in the garlic-fed groups than in the control (p < 0.05). Activities of catalase, superoxide dismutase and glutathione peroxidase in the hepatopancreas, activities of alanine aminotransferase, aspartate aminotransferase and levels of albumin and total protein in the hemolymph were significantly increased in the garlic treatments (p < 0.05). Furthermore, garlic supplemented diets improved muscle biochemical profiles, particularly contents of crude protein and total ash and upregulations of immune deficiency and heat shock proteins (HSP70) gene expression (p < 0.05). Therefore, garlic has positive effects on growth performance and physio-biochemical responses of M. rosenbergii, and thus, it can be used as an additive for stress resistance and as a growth promoter in sustainable aquaculture.

Sustainable and efficient technologies for removal and recovery of toxic and valuable metals from wastewater: Recent progress, challenges, and future perspectives

Due to their numerous effects on human health and the natural environment, water contamination with heavy metals and metalloids, caused by their extensive use in various technologies and industrial applications, continues to be a huge ecological issue that needs to be urgently tackled. Additionally, within the circular economy management framework, the recovery and recycling of metals-based waste as high value-added products (VAPs) is of great interest, owing to their high cost and the continuous depletion of their reserves and natural sources. This paper reviews the state-of-the-art technologies developed for the removal and recovery of metal pollutants from wastewater by providing an in-depth understanding of their remediation mechanisms, while analyzing and critically discussing the recent key advances regarding these treatment methods, their practical implementation and integration, as well as evaluating their advantages and remaining limitations. Herein, various treatment techniques are covered, including adsorption, reduction/oxidation, ion exchange, membrane separation technologies, solvents extraction, chemical precipitation/co-precipitation, coagulation-flocculation, flotation, and bioremediation. A particular emphasis is placed on full recovery of the captured metal pollutants in various reusable forms as metal-based VAPs, mainly as solid precipitates, which is a powerful tool that offers substantial enhancement of the remediation processes' sustainability and cost-effectiveness. At the end, we have identified some prospective research directions for future work on this topic, while presenting some recommendations that can promote sustainability and economic feasibility of the existing treatment technologies.

Multifactorial Screening Reveals New Insight into Early Cadmium Exposure and Garlic Interactions in Dicentrarchus labrax

Environmental pollutants and especially metal trace elements remain an unmitigated threat to the overall life support system. Their chemical stability and accumulation pattern in the ecosystem make them a persistent hazard. This study aims to characterize the early cadmium (Cd) histological and hematological alterations and their corresponding plasma indicators in the Mediterranean sea bass (Dicentrarchus labrax). We also assessed garlic potential to prevent cadmium toxicity. For this purpose, 200 fish of 55 g mean weight were separated into 3 cylindroconical fiberglass tanks of 500-L capacity, each with a stocking density of 4 kg m^-3. The fish were regularly hand-fed 0% (control group), 2%, and 6% garlic-supplemented diets to apparent satiation twice a day for 1 month. At the end of the experiment, we injected 22.2 mM cadmium (CdCl2) intraperitoneally to the experimental groups and a placebo solution (9% NaCl) to the control groups; liver, kidney, heart, and blood tissue alterations were monitored with a full screening of their plasmatic indicators, 24 h before and 48 h after Cd injection. Subsequently, whole blood count and blood smears were performed to follow up on Cd-induced vascular damages. Our data showed that Cd induced thrombotic thrombocytopenic purpura, leading to widespread bleeding and cellular alterations in the targeted tissues. These alterations were associated with an obvious normochromic normocytic anemia in favor of microangiopathic hemolytic anemia. Cd injection has also seriously inhibited the overall enzymatic activities triggering a metabolic shift. Although garlic supplementation had little effect on cadmium-induced alterations, it significantly reduced biomass dispersion. Our data is the first evidence of the cadmium versatile toxicity involving vascular alterations as a central and a leading cause of the overall parenchymal lesions. Cd toxicity was associated with a specific enzymatic signature, which must be considered during the interpretation.

Dietary garlic and chitosan enhanced the antioxidant capacity, immunity, and modulated the transcription of HSP70 and Cytokine genes in Zearalenone-intoxicated European seabass

The present study was performed to evaluate the toxic effects of feed-born zearalenone (ZEN) on antioxidative status, immunity, transcriptomic responses of European seabass, and the modulating roles of dietary garlic and/or chitosan powders. Fish (30.7 ± 0.6 g) were randomly arranged in five experimental groups (in triplicates), whereas the first group was fed on the control diet only without any supplements (control), and the second group was fed on the basal diet contaminated with ZEN (0.725 mg/kg diet). Three other groups were fed on ZEN-contaminated diets and simultaneously supplemented with garlic powder (GP) (30 g/kg diet) (ZEN + GP), chitosan powder (CH) (10 g/kg diet) (ZEN + CH), and a mixture of GP and CH (ZEN + GP + CH). Fish were fed on the experimental diets thrice a day for 4 weeks. Two-way ANOVA revealed a gradual decline in serum superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities in the ZEN group reaching their lowest levels at the 4th week. Contrariwise, malondialdehyde levels were markedly higher in the ZEN group reaching their highest values at the end of the experiment. A significant decline of total immunoglobulins (P < 0.05) was observed in the serum of the ZEN group, especially after the 4th week. Moreover, significant down-regulation of interleukin-4 (IL-4) and interleukin 1 beta (IL-1β) genes (P < 0.05) alongside significant up-regulation of tumor necrosis factor-alpha (TNF-α) and heat shock protein 70 (HSP70) genes (P < 0.05) in the liver and anterior kidney of ZEN-intoxicated group. Interestingly, dietary supplementation with GP and CH significantly attenuated ZEN-induced oxidative stress, immunosuppression, and modulated transcriptomic responses of ZEN-exposed fish. Moreover, combined dietary supplementation of both feed additives resulted in better effects than each one alone.

Dietary Phytogenics and Galactomannan Oligosaccharides in Low Fish Meal and Fish Oil-Based Diets for European Sea Bass (Dicentrarchus labrax) Juveniles: Effects on Gill Structure and Health and Implications on Oxidative Stress Status

An effective replacement for fish meal (FM) and fish oil (FO) based on plant-based raw materials in the feed of marine fish species is necessary for the sustainability of the aquaculture sector. However, the use of plant-based raw materials to replace FM and FO has been associated with several negative health effects, some of which are related to oxidative stress processes that can induce functional and morphological alterations in mucosal tissues. This study aimed to evaluate the effects of dietary oligosaccharides of plant origin (5,000 ppm; galactomannan oligosaccharides, GMOS) and a phytogenic feed additive (200 ppm; garlic oil and labiatae plant extract mixture, PHYTO) on the oxidative stress status and mucosal health of the gills of juvenile European sea bass (Dicentrarchus labrax). The experimental diets, low FM and FO diets (10%FM/6%FO) were supplemented with GMOS from plant origin and PHYTO for 63 days. GMOS and PHYTO did not significantly affect feed utilization, fish growth, and survival. GMOS and PHYTO downregulated the expression of β-act, sod, gpx, cat, and gr in the gills of the fish compared with that in fish fed the control diet. The expression of hsp70 and ocln was upregulated and downregulated, respectively, in the GMOS group compared with that in the control group, whereas the expression of zo-1 was downregulated in the PHYTO group compared with that in the GMOS group. The morphological, histopathological, immunohistochemical, and biochemical parameters of the fish gills were mostly unaffected by GMOS and PHYTO. However, the PHYTO group had lower incidence of lamellar fusion than did the control group after 63 days. Although the tissular distribution of goblet cells was unaffected by GMOS and PHYTO, goblet cell size showed a decreasing trend (−11%) in the GMOS group. GMOS and PHYTO significantly reduced the concentration of PCNA+ in the epithelium of the gills. The above findings indicated that GMOS and PHYTO in low FM/FO-based diets protected the gill epithelia of D. labrax from oxidative stress by modulating the expression of oxidative enzyme-related genes and reducing the density of PCNA+ cells in the gills of the fish.

Carvacrol, Thymol, and Garlic Essential Oil Promote Skin Innate Immunity in Gilthead Seabream (Sparus aurata) Through the Multifactorial Modulation of the Secretory Pathway and Enhancement of Mucus Protective Capacity

One of the main targets for the use of phytogenics in aquafeeds is the mucosal tissues as they constitute a physical and biochemical shield against environmental and pathogenic threats, comprising elements from both the innate and acquired immunity. In the present study, the modulation of the skin transcriptional immune response, the bacterial growth capacity in skin mucus, and the overall health condition of gilthead seabream (Sparus aurata) juveniles fed a dietary supplementation of garlic essential oil, carvacrol, and thymol were assessed. The enrichment analysis of the skin transcriptional profile of fish fed the phytogenic-supplemented diet revealed the regulation of genes associated to cellular components involved in the secretory pathway, suggesting the stimulation, and recruitment of phagocytic cells. Genes recognized by their involvement in non-specific immune response were also identified in the analysis. The promotion of the secretion of non-specific immune molecules into the skin mucus was proposed to be involved in the in vitro decreased growth capacity of pathogenic bacteria in the mucus of fish fed the phytogenic-supplemented diet. Although the mucus antioxidant capacity was not affected by the phytogenics supplementation, the regulation of genes coding for oxidative stress enzymes suggested the reduction of the skin oxidative stress. Additionally, the decreased levels of cortisol in mucus indicated a reduction in the fish allostatic load due to the properties of the tested additive. Altogether, the dietary garlic, carvacrol, and thymol appear to promote the gilthead seabream skin innate immunity and the mucus protective capacity, decreasing its susceptibility to be colonized by pathogenic bacteria.

Unveiling the effect of dietary essential oils supplementation in Sparus aurata gills and its efficiency against the infestation by Sparicotyle chrysophrii

A microencapsulated feed additive composed by garlic, carvacrol and thymol essential oils (EOs) was evaluated regarding its protective effect in gills parasitized by Sparicotyle chrysophrii in Sparus aurata. A nutritional trial (65 days) followed by a cohabitation challenge with parasitized fish (39 days) were performed. Transcriptomic analysis by microarrays of gills of fish fed the EOs diet showed an up-regulation of genes related to biogenesis, vesicular transport and exocytosis, leukocyte-mediated immunity, oxidation–reduction and overall metabolism processes. The functional network obtained indicates a tissue-specific pro-inflammatory immune response arbitrated by degranulating acidophilic granulocytes, sustained by antioxidant and anti-inflammatory responses. The histochemical study of gills also showed an increase of carboxylate glycoproteins containing sialic acid in mucous and epithelial cells of fish fed the EOs diet, suggesting a mucosal defence mechanism through the modulation of mucin secretions. The outcomes of the in vivo challenge supported the transcriptomic results obtained from the nutritional trial, where a significant reduction of 78% in the abundance of S. chrysophrii total parasitation and a decrease in the prevalence of most parasitic developmental stages evaluated were observed in fish fed the EOs diet. These results suggest that the microencapsulation of garlic, carvacrol and thymol EOs could be considered an effective natural dietary strategy with antiparasitic properties against the ectoparasite S. chrysophrii.

The potential modulatory role of herbal additives against Cd toxicity in human, animal, and poultry: a review

Cadmium (Cd) is a heavy and toxic metal and easily absorbed by animals and plants; subsequently, it is an environmental risk factor with several toxic effects in humans and animals. The main pathway of human or animal exposure to Cd is through its ingestion by water or food and by particles or fume inhalation during industrial processes. With continuous exposure to small levels of cadmium, it is being deposited in different tissues day after day, causing toxic effects on the liver, kidney, and testes. Long-term exposure to this toxic metal resulted in inflammatory infiltration, necrosis of hepatocytes, degenerative changes in testis tissues, reduction in spermatocytes, degeneration in renal tubules, and hypertrophy of renal epithelium. Therefore, we need an effective treatment to overcome cadmium poisoning. Thus, in the current review, we try to provide compiled reports and summarize information about the toxicological effects of Cd in human, animals, and poultry. This review also provides updated information about the protective actions of herbs and herbal extracts and their role as an effective strategy in reducing or preventing serious health problems and tissue damage in response to Cd toxicity.