Cadmium-induced oxidative stress and apoptotic changes in the testis of freshwater crab, Sinopotamon henanense

Effect of salinity on the toxicokinetics, oxidative stress, and metallothionein gene expression in Meretrix meretrix exposed to cadmium

To understand the effect of salinity on the toxicokinetics, oxidative stress, and detoxification of cadmium-exposed Meretrix meretrix, M. meretrix were acclimatized to different salinities (8, 14, 20, 26, and 32 ppt) for 14 d, exposed to 10 μg/L Cd for 7 d, followed by a 28-day depuration period. The internal Cd concentration was determined, and the activities of antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), and glutathione-S-transferase (GST)), and the malondialdehyde (MDA) content were measured. The mRNA expression levels of antioxidant enzyme (Cu/Zn SOD, CAT) and detoxification-related genes metallothionein (MT) were analyzed. The mean concentrations of Cd in M. meretrix tissues were in the order gill > digestive gland > mantle > axe foot. The Cd uptake rate in the four tissues decreased with increasing salinity (range: 14-26 ppt). The Cd elimination half-lives were the highest at 8 ppt and 14 ppt salinity. Cadmium activated the four oxidative stress-related related enzymes in the gills. At the end of accumulation period, Cd exposure at 20 ppt salinity significantly increased the expression of Cu/Zn SOD. CAT expression was significantly inhibited at 20 ppt salinity, but was induced at 32 ppt. MT mRNA expression was only induced under Cd at 20 ppt salinity. At the end of depuration period, Cu/Zn SOD expression was inhibited at salinities of 8, 14, and 26 ppt. The results indicated that SOD, CAT, GST, MDA, Cu/Zn SOD, CAT, and MT were sensitive to cadmium in a water environment, and can be used as indicators of marine heavy metal pollution.

Multi-endpoint analysis of cadmium chloride-induced genotoxicity shows role for reactive oxygen species and p53 activation in DNA damage induction, cell cycle irregularities, and cell size aberrations

Cadmium chloride (CdCl2) is a known genotoxic carcinogen, with a mechanism of action thought to partly involve the generation of reactive oxygen species (ROS). We applied here a multi-endpoint approach in vitro to explore the impact of CdCl2 on both the genome and on wider cell biology pathways relevant to cancer. Multi-endpoint approaches are believed to offer greater promise in terms of understanding the holistic effects of carcinogens in vitro. This richer understanding may help better classification of carcinogens as well as allowing detailed mechanisms of action to be identified. We found that CdCl2 caused DNA damage [micronuclei (MN)] in both TK6 and NH32 cells in a dose-dependent manner after 4 h exposure (plus 23 h recovery), with lowest observable effect levels (LOELs) for MN induction of 1 μM (TK6) and 1.6 μM (NH32). This DNA damage induction in TK6 cells was ROS dependent as pretreatment with the antioxidant N-Acetyl Cysteine (1 mM), abrogated this effect. However, 2',7'-dichlorofluorescin diacetate was not capable of detecting the ROS induced by CdCl2. The use of NH32 cells allowed an investigation of the role of p53 as they are a p53 null cell line derived from TK6. NH32 showed a 10-fold increase in MN in untreated cells and a similar dose-dependent effect after CdCl2 treatment. In TK6 cells, CdCl2 also caused activation of p53 (accumulation of total and phosphorylated p53), imposition of cell cycle checkpoints (G2/M) and intriguingly the production of smaller and more eccentric (elongated) cells. Overall, this multi-endpoint study suggests a carcinogenic mechanism of CdCl2 involving ROS generation, oxidative DNA damage and p53 activation, leading to cell cycle abnormalities and impacts of cell size and shape. This study shows how the integration of multiple cell biology endpoints studied in parallel in vitro can help mechanistic understanding of how carcinogens disrupt normal cell biology.

The impact of ocean acidification and cadmium toxicity in the marine crab Scylla serrata: Biological indices and oxidative stress responses

Ocean acidification (OA) and heavy metal pollution in marine environments are potentially threatening marine life. The interactive effect of OA and heavy metals could be more vulnerable to marine organisms than individual exposures. In the current study, the effect of OA on the toxicity of cadmium (Cd) in the crab Scylla serrata was evaluated. Crab instars (0.07 cm length and 0.1 g weight) were subjected to pH 8.2, 7.8, 7.6, 7.4, 7.2, and 7.0 with and without 0.01 mg l-1 of Cd for 60 days. We noticed a significant decrease in growth, molting, protein, carbohydrate, amino acid, lipid, alkaline phosphatase, and haemocytes of crabs under OA + Cd compared to OA treatment. In contrast, the growth, protein, amino acid, and haemocyte levels were significantly affected by OA, Cd, and its interactions (OA + Cd). However, superoxide dismutase, catalase, lipid peroxidation, glutamic oxaloacetate transaminase, glutamic pyruvate transaminase, and accumulation of Cd in crabs were considerably elevated in OA + Cd treatments compared to OA alone treatments. The present investigation showed that the effect of Cd toxicity might be raised under OA on S. serrata. Our study demonstrated that OA significantly affects the biological indices and oxidative stress responses of S. serrata exposed to Cd toxicity.

Hemocytes: A Useful Tool for Assessing the Toxicity of Microplastics, Heavy Metals, and Pesticides on Aquatic Invertebrates

Invertebrates have long been an important tool for assessing water pollution due to their characteristics as intermediate consumers in aquatic ecosystem food chains. Most of the time, the effects of contaminants are measured by their effect on oxidative status or by mortality, although there already exists an easier tool-hemocytes. Hemocytes are circulating cells with a very important role in the immune system of invertebrates, which can be found within the hemolymph, analogous to the blood in vertebrates. The collection of hemolymph samples is easy, fast, minimally invasive, and poses no danger to the life of invertebrates. The purpose of this review was to highlight the advantages of using hemolymph for toxicity assays of various substances, including heavy metals, micro- and nano-plastics, pesticides, hydrocarbons, and oil spills. A literature search was conducted for this purpose using the most common and most often used databases, with a focus on the most recent and relevant studies. Bivalve mollusks, crustaceans, and gastropods were chosen for this investigation. This review found a growing number of studies choosing to use hemolymph as the standard methodology for toxicology assays, confirming their qualities as reliable tools.

Impact of Heavy Metal Toxicity on the Gut Microbiota and Its Relationship with Metabolites and Future Probiotics Strategy: a Review

The gut microbiota has a vital role in the maintenance of intestinal homeostasis. Several studies have revealed that environmental exposure to pollutants such as heavy metals may contribute to the progression of extensive list of diseases which may further lead to perturbations in the gut leading to dysbiosis. This manuscript critically reviews the alterations in the gut microbiota composition and function upon exposure to various toxic heavy metals prevalent in the environment. The disturbance in gut microbial ecology also affects the microbial metabolic profile which may alter the speciation state and bioavailability heavy metals thus affecting metal uptake-absorption/detoxification mechanisms associated to heavy metal metabolism. The toxic effects of various heavy metals either in single or in multimetallic combination and the gut microbiota associated host health and disease condition need a comprehensive assessment with important consideration for therapeutic and protective strategies against the damage to gut microbiota.

Mechanisms of Cadmium-Induced Testicular Injury: A Risk to Male Fertility

Cadmium is a heavy toxic metal with unknown biological functions in the human body. Over time, cadmium accretion in the different visceral organs (liver, lungs, kidney, and testis) is said to impair the function of these organs, which is associated with a relatively long biological half-life and a very low rate of excretion. Recently studies have revealed that the testes are highly sensitive to cadmium. In this review, we discussed the adverse effect of cadmium on the development and biological functions of the testis. The Sertoli cells (SCs), seminiferous tubules, and Blood Testis Barrier are severely structurally damaged by cadmium, which results in sperm loss. The development and function of Leydig cells are hindered by cadmium, which also induces Leydig cell tumors. The testis's vascular system is severely disturbed by cadmium. Cadmium also perturbs the function of somatic cells and germ cells through epigenetic regulation, giving rise to infertile or sub-fertile males. In addition, we also summarized the other findings related to cadmium-induced oxidative toxicity, apoptotic toxicity, and autophagic toxicity, along with their possible mechanisms in the testicular tissue of different animal species. Consequently, cadmium represents a high-risk factor for male fertility.

Biotin alleviates hepatic and intestinal inflammation and apoptosis induced by high dietary carbohydrate in juvenile turbot (Scophthalmus maximus L.)

Excessive dietary carbohydrate commonly impairs the functions of liver and intestine in carnivorous fish. In the present study, a 10-week feeding trial was carried out to explore the regulation of biotin on the hepatic and intestinal inflammation and apoptosis in turbot (Scophthalmus maximus L.) fed with high carbohydrate diets. Three isonitrogenous and isolipidic experimental diets were designed as follows: the CC diet with 18.6% of carbohydrate and 0.04 mg/kg of biotin, the HC diet with 26.9% of carbohydrate and 0.05 mg/kg of biotin, and the HCB diet with 26.9% of carbohydrate and 1.62 mg/kg of biotin. Results showed that high dietary carbohydrate (HC diet) impaired the morphology of liver and intestine, however, inclusion of dietary biotin (HCB diet) normalized their morphology. Inflammation-related gene expression of nuclear factor κB p65 (nf-κb p65), tumor necrosis factor α (tnf-α), interleukin-1β (il-1β), il-6 and il-8, and the protein expression of NF-κB p65 in the liver and intestine were significantly up-regulated in the HC group compared to those in the CC group (P < 0.05), the HCB diet decreased their expression compared to the HC group (P < 0.05). The gene expression of il-10 and transforming growth factor-β (tgf-β) in the liver and intestine were significantly decreased in the HC group compared to the CC group (P < 0.05), and inclusion of dietary biotin increased the il-10 and tgf-β expression in the liver and intestine (P < 0.05). Moreover, compared to the CC group, the HC group had a stronger degree of DNA fragmentation and more TUNEL-positive cells in the liver and intestine, and the HCB group had a slighter degree of DNA fragmentation and fewer TUNEL-positive cells compared to the HC group. Meanwhile, the gene expression of B-cell lymphoma protein-2-associated X protein (bax) and executor apoptosis-related cysteine peptidase 3 (caspase-3) were significantly up-regulated and the gene expression of B-cell lymphoma-2 (bcl-2) was significantly down-regulated both in the liver and intestine in the HC group compared with those in the CC group (P < 0.05). Inclusion of dietary biotin significantly decreased the bax and caspase-3 mRNA levels and increased bcl-2 mRNA level in the liver and intestine (P < 0.05). In conclusion, high dietary carbohydrate (26.9% vs 18.6%) induced inflammation and apoptosis in liver and intestine. Supplementation of biotin (1.62 mg/kg vs 0.05 mg/kg) in diet can alleviate the high-dietary-carbohydrate-induced hepatic and intestinal inflammation as well as inhibit apoptosis in turbot. The present study provides basic data for the application of biotin into feed, especially the high-carbohydrate feed for turbot.

The health risk for consumers under heavy metal scenarios: Reduce bioaccumulation of Cd in estuary mud crab (Scylla paramamosain) through the antagonism of Se

Heavy metal pollution has gained increasing attention over past years, and notably, cadmium (Cd) is a non-essential heavy metal that can be toxic to human and wildlife. Furthermore, selenium (Se) is a component of the selenoproteins and influences the toxicity of Cd in different organisms, and protect organisms as a kind of heavy metal antagonist. This study exposed mud crab to 5.0 mg/L Cd for 28 days, and investigated whether different concentrations (0.1, 0.2, 0.3 mg/kg) of selenite (Na₂SeO₃) or selenomethionine (SeMet) affect the bioaccumulation of Cd, serum biochemical index, antioxidant and stress-response genes of S. paramamosain. The results showed that the Cd concentration in Cd group was significantly higher than the organic or inorganic Se group. Serum biochemical index demonstrated that Se might relieve the damage or dysfunction of hepatopancreas caused by both Cd accumulation and toxicity. Furthermore, Se improved CAT, GPx T-AOC and SOD activity, and decreased MDA concentrations and the lipid peroxidation levels, antagonistic to Cd. Then, this study analyzed the expression of 26 stress-related genes, the results indicated that the inorganic and organic Se might reduce the damage of cell and the toxicity of heavy metals in the hepatopancreas after Cd exposure. Therefore, this study indicated that Se might alleviate Cd toxicity via the different antioxidative mechanisms, and increased the understanding of environmental toxins on estuary crustaceans.

Curative Potential of Substances with Bioactive Properties to Alleviate Cd Toxicity: A Review

Rapid urbanization and industrialization have led to alarming cadmium (Cd) pollution. Cd is a toxic heavy metal without any known physiological function in the organism, leading to severe health threat to the population. Cd has a long half-life (10-30 years) and thus it represents serious concern as it to a great extent accumulates in organs or organelles where it often causes irreversible damage. Moreover, Cd contamination might further lead to certain carcinogenic and non-carcinogenic health risks. Therefore, its negative effect on population health has to be minimalized. As Cd is able to enter the body through the air, water, soil, and food chain one possible way to defend and eliminate Cd toxicities is via dietary supplements that aim to eliminate the adverse effects of Cd to the organism. Naturally occurring bioactive compounds in food or medicinal plants with beneficial, mostly antioxidant, anti-inflammatory, anti-aging, or anti-tumorigenesis impact on the organism, have been described to mitigate the negative effect of various contaminants and pollutants, including Cd. This study summarizes the curative effect of recently studied bioactive substances and mineral elements capable to alleviate the negative impact of Cd on various model systems, supposing that not only the Cd-derived health threat can be reduced, but also prevention and control of Cd toxicity and elimination of Cd contamination can be achieved in the future.

Phytomedicinal therapeutics for male infertility: critical insights and scientific updates

Infertility is a significant cause of anxiety, depression, and social stigma among couples and families. In such cases, male reproductive factors contribute widely to the extent of 20-70%. Male infertility is a multifactorial disease with several complications contributing to its diagnosis. Although its management encompasses both modern and traditional medicine arenas, the first line of treatment, adopted by most males, focuses on the reasonably successful medicinal plant-based conventional therapies. Phyto-therapeutics, which relies on active ingredients from traditionally known herbs, influences sexual behavior and male fertility factors. The potency of these phyto-actives depends on their preparation methods and forms of consumption, including decoctions, extracts, semi-purified compounds, etc., as inferred from in vitro and in vivo (laboratory animal models and human) studies. The mechanisms of action therein involve the testosterone pathway for stimulation of spermatogenesis, reduction of oxidative stress, inhibition of inflammation, activation of signaling pathways in the testes [extracellular-regulated kinase (ERK)/protein kinase B(PKB)/transformation of growth factor-beta 1(TGF-β1)/nuclear factor kappa-light-chain-enhancer of activated B cells NF-kB signaling pathways] and mediation of sexual behavior. This review critically focuses on the medicinal plants and their potent actives, along with the biochemical and molecular mechanisms that modulate vital pathways associated with the successful management of male infertility. Such intrinsic knowledge will significantly further studies on medicinal plants that improve male reproductive health.

Cadmium-induced ultrastructural changes and apoptosis in the gill of freshwater mussel Anodonta woodiana

This study investigated the acute toxicity of cadmium (Cd) to the freshwater mussel Anodonta woodiana. The freshwater mussels were exposed to five concentrations of Cd (0 mg/L, 8.43 mg/L, 16.86 mg/L, 33.72 mg/L, and 67.45 mg/L) for up to 96 h. The 24-h, 48-h, 72-h, and 96-h LC₅₀ values for Cd were estimated as 562.3 mg/L, 331.1 mg/L, 182.0 mg/L, and 134.9 mg/L, respectively. Caspase-3, caspase-8, caspase-9, and Ca-ATPase activities; protein and H₂O₂ levels; DNA fragmentation; and ultrastructure of the gill were also investigated. The activities of caspase-3 and caspase-9 in mussels were increased by Cd in a dose-dependent manner, where higher doses of Cd (33.72 mg/L and 67.45 mg/L) significantly increased the enzyme activities compared to the controls (P < 0.05). The caspase-8 activity was significantly depressed by a low dose of Cd (8.43 mg/L) but was clearly induced by higher doses of Cd (16.86 mg/L, 33.72 mg/L, and 67.45 mg/L) (P < 0.05). The Ca-ATPase activity and H₂O₂ levels were elevated and reached maximum values under the medium dose of Cd (16.86 mg/L). However, protein levels were decreased by Cd in an inverse dose-dependent manner. In the gills of the mussels, Cd treatment induced DNA fragmentation as demonstrated by DNA ladders observed via agarose gel electrophoresis. Moreover, ultrastructural alterations in gill cells of mussels treated with Cd (16.86 mg/L and 67.45 mg/L) for 96 h were observed by electronic microscopy. The ultrastructure abnormalities were characterized by the following features: (1) a disordered arrangement and breaking off of microvilli of epithelial cells; (2) chromatin condensed near the nuclear membrane and the appearances of extremely irregular nuclei, some with a fingerlike shape and an unclear, swollen, invaginated, or ruptured nuclear membrane and apoptotic bodies; (3) swollen and vacuolating mitochondria, some with disintegrated or missing cristae; (4) a disintegrated rough endoplasmic reticulum containing different sizes of vesicles; and (5) shrinking and deformation of Golgi bodies with decreased vesicle numbers. Our results demonstrated that Cd could activate caspase-3, caspase-8, caspase-9, and Ca-ATPase; cause ultrastructural changes; and produce DNA fragmentation in the mussels investigated. Based on the information obtained through this study, it is reasonable to conclude that Cd can induce apoptosis in the gills of the mussels, eventually leading to tissue damage.

Changes in heavy metal levels, reproductive characteristics, oxidative stress markers and testicular apoptosis in rams raised around thermal power plant

Male reproductive dysfunction is one of the damages in the organism caused by heavy metals. In this study, it was aimed to investigate the changes in heavy metal levels in serum and testicular tissue, and serum hormone levels, epididymal spermatozoa characteristics, tissue oxidative stress levels, testicular histology and testicular apoptosis level in rams raised in remote and near regions of a thermal power plant. A total of 75 rams were divided into 3 groups according to the regions, where they were born and raised, being far [250 km distance, group 1 (control), n = 25], close (20 km distance, group 2, n = 25) and very close (10 km distance, group 3, n = 25) to the thermal power plant. The blood along with testis and epididymis tissues was taken from the animals after slaughtering. In addition, soil and water heavy metal analyzes were also performed. The highest levels of serum Al, Cr, As, Ag, Sn and testicular Al, V, Ni, Ag, Cd, Cr, As, Pb, and the lowest levels of serum Cu, testicular Cu and Zn were determined in group 3 compared to control. Soil and water heavy metal results were similar to those found in serum and testis. The lowest serum testosterone level, tissue glutathione-peroxidase and catalase activities, spermatozoon concentration, and the highest tissue malondialdehyde level, dead spermatozoon rate, Bax apoptotic protein expression level and Bax/Bcl-2 rate alongside some testicular histopathological lesions were found in group 3 in comparison to control. Significant correlations were determined between some heavy metal levels and some parameters measured. As a result, heavy metals accumulate in the soil and water in the region close to the thermal power plant. The endocrine and exocrine reproductive potentials of rams born and grown in these regions were clearly damaged by the increased testicular heavy metals due to water drank and herbs consumed.

Cadmium attenuates testosterone synthesis by promoting ferroptosis and blocking autophagosome-lysosome fusion

Ferroptosis is a newly defined programmed cell death pathway characterized by iron overload and lipid peroxidation. Increasing studies show that autophagy regulates testosterone synthesis and promotes ferroptosis. Testosterone is essential for sexual development and the maintenance of male characteristics. The deficiency of testosterone induced by cadmium (Cd) can severely affect male fertility. However, the underlying mechanism of testosterone reduction after Cd exposure remains blurry. In this study, we found that Cd affected iron homeostasis and elicited ferroptosis, ultimately reducing testosterone production. Mechanically, our findings revealed that Cd-induced ferroptosis depended upon the excessive activation of Heme oxygenase 1 (HMOX1) and the release of free iron from heme. Additionally, Cd exposure promoted autophagosome formation but blocked autophagosome-lysosome fusion, which attenuated the absorption of total cholesterol and triglycerides, further aggravating testosterone synthesis disorder. Collectively, Cd induced ferroptosis by iron homeostasis dysregulation, mediated by excessive activation of HMOX-1. The disruption of autophagy flow contributed to Cd-induced testicular dysfunction and attenuated testosterone synthesis.

Characterization of p53 From the Marine Crab Portunus trituberculatus and Its Functions Under Low Salinity Conditions

Portunus trituberculatus, or the swimming crab, is tolerant of reduced salinity; however, the molecular mechanism of this tolerance is not clear. Cells can be damaged by hyperosmotic salinity. The protein p53, sometimes referred to as “the guardian of the genome,” displays versatile and important functions under changing environmental conditions. Herein, the P. trituberculatus p53 gene (designated as Ptp53) was cloned and studied. The full-length Ptp53 cDNA comprised 1,544bp, with a 1,314bp open reading frame, which encodes a putative polypeptide of 437 amino acids. Quantitative real-time reverse transcription PCR assays revealed ubiquitous expression of Ptp53 in all tissues examined, with the gills showing the highest expression level. Extensive apoptosis was detected under low salinity conditions using terminal deoxynucleotidyl transferase nick-end-labeling staining. Oxidative stress was induced under low salinity conditions, consequently leading to apoptosis. Low salinity stress caused significant upregulation of Ptp53 mRNA and protein levels in the gills. Moreover, compared with that in the control group, the mortality of Ptp53-silenced crabs under low salinity stress was enhanced significantly. Taken together, our findings suggest that Ptp53, via regulation of apoptosis and antioxidant defense, played important functions in the low salinity stress response of the swimming crab.

Metal(loid)s and human semen quality: The LIFE Study

Multiple studies have demonstrated a global population-wide decline in semen quality, with sperm concentrations having fallen 50 % over the past 50 years. Several metal and metalloid ("metal(loid)") compounds are known to have testicular toxicity, raising concerns about their contribution to rising infertility. In the male reproductive tract, metal(loid)s can reduce semen quality and disturb function both directly, by inducing tissue damage, and indirectly, by disrupting hormone production and secretion. This study assessed associations between 15 creatinine-adjusted metal(loid)s and 7 measures of semen quality among 413 reproductive-aged men recruited from 16 U.S. counties between 2005-2009. Multi-metal(loid) multivariable linear regression models estimated associations between semen quality endpoints and urinary concentrations of chromium, cobalt, copper, molybdenum, selenium, zinc, antimony, arsenic, barium, cadmium, lead, thallium, tin, tungsten, and uranium. LASSO regression was employed to select model variables and account for multicollinearity of the metal(loid)s. A positive association was observed between tin and sperm morphology (β = 4.92 p = 0.045). Chromium (β = 1.87, p = 0.003) and copper (β= -1.30, p = 0.028) were positively and negatively associated with total sperm count, respectively. With respect to DNA fragmentation, cadmium (β = 12.73, p = 0.036) was positively associated and chromium was negatively associated (β = -5.08, p = 0.001). In this cohort of U.S. population-based men, there was evidence of both positive and negative associations between specific metal(loid)s and semen quality. Additional research is needed to determine interactions between metal(loid)s within a mixture, consistent with typical human exposure, and identify sperm effects resulting from cumulative metal(loid) exposures.

Protective Effect of Quercetin on Testis Structure and Apoptosis Against Lead Acetate Toxicity: an Stereological Study

Exposure to environmental pollutants tightly impacts on the male fertility. In the present study, we examined the toxic effects of lead acetate (Pb) on testicular structure and the possible effect of quercetin on mitigating these effects. The apoptotic changes in the testes were also studied by the TUNEL assay and changes in apoptosis-related gene (Bax, Bcl-2, and caspase-3) expression. Twenty-one male mice were randomly divided into 3 groups of control, Pb, and lead acetate + quercetin. Testicular weight, both absolute and relative, was higher in Pb-exposed mice in comparison with the control and Pb-quercetin groups. The increase in size of testis was related to the lumen and connective tissue in this group. Lead acetate induced different patterns in testicular cell number; as spermatogonia, spermatocyte, and Sertoli cells number did not affect in lead acetate exposed group, while total number of round spermatids and long spermatids significantly reduced. In addition, Bcl-2 expression was downregulated, and Bax expression was upregulated in Pb-treated group in comparison with the control and Pb + quercetin groups. The TUNEL assay revealed that the number of apoptotic cells in Pb-treated group were increaed significantley in comparison to other groups. In conclusion, Pb administration adversely impacted on the cellular organization and activation of the apoptotic pathways in the testis; on the other hand, quercetin co-administration with lead partially ameliorated these adverse effects.

Ion regulation in a freshwater crab, Potamonautes warreni: The effects of trace metal exposure

Crustaceans inhabiting metal-contaminated freshwaters are susceptible to toxic insult to their osmoregulatory systems. The main osmoregulatory organs of decapod crustaceans, the gills, are continually bathed in freshwater and are therefore at risk from trace metal impacts. The effects of chronic (21 d) exposure to raised dissolved concentrations of Zn, Cd, Cu and Pb on aspects of hydromineral balance were investigated in Potamonautes warreni, a freshwater crab endemic to rivers in South Africa at potential risk from trace metal contamination from mining operations. Generally, hydromineral balance of P. warreni was tolerant to chronic metal exposures although sublethal cadmium exposure of 860 µg.l^-1 for 21 days resulted in a reduced sodium concentration in the haemolymph. A chronic exposure to 43 µg.l^-1 cadmium produced an elevated maximum unidirectional sodium uptake, possibly resulting from acclimation to the metal exposure. Branchial Na⁺/K⁺-ATPase and V-Type H⁺-ATPase activity were not affected by chronic in vivo Cd (43 µg.l^-1) and Zn (500 µg.l^-1) exposures. An important aspect of ameliorating metal toxicity may be through antioxidants and therefore the effects of applying a reducing agent were tested following in vitro metal treatment. Inhibition of Na⁺/K⁺-ATPase could be prevented by pre-incubation with a reducing agent, indicating the importance of antioxidants in reducing metal toxicity in this species. Although this study demonstrates the physiological resilience of P. warreni to dissolved trace metal impacts, the energetic consequences of long-term exposure are as yet not known.

Impact of Oxidative Stress on Male Reproduction in Domestic and Wild Animals

Oxidative stress occurs when the levels of reactive oxygen species (ROS) overcome the antioxidant defenses of the organism, jeopardizing several biological functions, including reproduction. In the male reproductive system, oxidative stress not only impairs sperm fertility but also compromises offspring health and survival, inducing oxidative damage to lipids, proteins and nucleic acids. Although a clear link between oxidative stress and male fertility disorders has been demonstrated in humans and laboratory rodents, little information is available about the implications of impaired redox homeostasis in the male fertility of domestic and wild animals. Therefore, this review aims to provide an update regarding the intrinsic and extrinsic factors that are associated with oxidative stress in the male reproductive system and their impact on the reproductive performance of domestic and wild animals. The most recent strategies for palliating the detrimental effects of oxidative stress on male fertility are reviewed together with their potential economic and ecological implications in the livestock industry and biodiversity conservation.

Quercetin mediated attenuation of cadmium-induced oxidative toxicity and apoptosis of spermatogenic cells in caprine testes in vitro

Cadmium (Cd), an environmental toxic heavy metal, has been reported to cause testicular toxicity, which contributes to the recent decline in male fertility worldwide. Quercetin (Qcn), a major dietary antioxidant, has been shown to have protective effects under various pathological conditions. However, whether Qcn provides protection against Cd-stimulated testicular toxicity remains obscured. The present study was therefore aimed at investigating the ameliorative effect of Qcn supplementation on Cd-induced toxicity in the goat testis in vitro in a dose-(10, 50, and 100 μM) and time-dependent (4 and 8 h) manner. Different cytotoxicity, genotoxicity, and biochemical analyses have been carried out using appropriate methods. Cytotoxicity in testicular cells induced by Cd treatment was apparently mitigated by Qcn treatment, evidenced by decreased apoptotic attributes or frequency in Qcn plus Cd-treated groups compared to the only Cd-treated groups. Qcn treatment provides substantial protection to the Cd-triggered aggression in oxidative (increased MDA levels) and total antioxidant capacity (reduced FRAP activity) in testicular tissue, indicating the anti-oxidative function of Qcn against Cd exposure. Moreover, Cd-induced decline in antioxidant status (CAT, SOD, and GST activity) was markedly restored by Qcn supplementation in testicular tissue. In conclusion, this study shows that Qcn treatment significantly attenuated the Cd-evoked testicular damage, suggesting its beneficial potential in preventing or at least in managing the gonadotoxicity in males induced by steadily increasing Cd contamination in the environment.

Reproductive toxicity of cadmium in pubertal male rats induced by cell apoptosis

Cadmium (Cd) is a heavy metal that is widely present in modern industrial production. It is a known, highly toxic environmental endocrine disruptor. Long-term exposure to Cd can cause varying degrees of damage to the liver, kidney, and reproductive system of organisms, especially the male reproductive system. This study aimed to explore the mechanism of Cd toxicity in the male reproductive system during puberty. Eighteen healthy 6-week-old male Sprague-Dawley rats were randomly divided into three groups (control group, low-dose group, and high-dose group) according to their body weight, with six in each group. Cd (0, 1, and 3 mg/kg/day) was given by gavage for 28 consecutive days. The results showed that Cd exposure to each dose group caused a decrease in the testicular organ coefficient and sperm count, compared with the control group. Cd exposure resulted in significant changes in testicular morphology in the 3 mg/kg/day Cd group. In the 1 and 3 mg/kg/day Cd groups, serum testosterone decreased and apoptosis of testicular cells increased significantly (p < 0.05). In addition, compared with the control group, the activity of glutathione peroxidase and superoxide dismutase in each Cd exposure dose group decreased, but the content of malondialdehyde in the high-dose, 3 mg/kg/day Cd treatment group significantly increased (p < 0.05). Although Cd exposure caused an increase in the messenger RNA (mRNA) levels of Bcl-2, Caspase-3 and Caspase-9 in the testicular tissues (p < 0.05), Bcl-2 expression was unchanged (p > 0.05). The expression level of Akt mRNA in testicular tissue of rats in the high-dose 3 mg/kg/day Cd group was increased (p < 0.05). Our data suggest that Cd affected testosterone levels, and apoptosis was observed in spermatids.

The role of Nrf2 in mitigating cadmium-induced oxidative stress of Marsupenaeus japonicus

Nuclear factor-erythroid 2-related factor-2 (Nrf2) is an important modulator of cellular responses against Cd in mammalian cells. However, whether such modulation is conserved in Marsupenaeus japonicas remains unknown.In our study, the shrimps were injected with dsRNA targeting Nrf2 at 4 μg g^-1 body weight (b.w.) or sulforaphane (SFN) at 5 μg g^-1 b.w., and then were exposed to 40 mg L^-1 CdCl₂ for 48 h. After Nrf2 knockdown, the Cd content increased, but decreased in the SFN group. This suggested that Nrf2 could promote Cd excretion. A terminal deoxynulceotidyl transferase nick-end-labeling (TUNEL) assay revealed that the Nrf2 knockdown increased the number of apoptotic cells in M. japonicas, while SFN decreased the number of apoptotic cells. After Nrf2 knockdown, the total antioxidant capacity (T-AOC), superoxide dismutase (Sod) activity, and related gene expression decreased significantly, while the malondialdehyde (MDA) content increased remarkably. By contrast, SFN injection alleviated the oxidative stress, as evidenced by increased T-AOC, Sod activity, sod mRNA expression and a reduced MDA content. Similarly, detoxification related enzyme activities (ethoxyresorufin O-deethylase and glutathione-S-transferase (GST)) and their corresponding gene expressions (cyp3a (cytochrome P450 family 3 subfamily A) and gst) were suppressed in the ds-Nrf2 injection group, while they were elevated in the SFN group. In addition, ds-Nrf2 activated mitochondrial apoptotic pathway, as evidenced the mRNA and protein levels of caspase-3, Bcl2 associated X protein (Bax), and p53, while SFN treatment suppressed them. These results displayed that in M. japonicus Cd-induced cellular oxidative damage probably acts via the Nrf2 pathway.

Intergenerational effects of resuspended sediment and trace metal mixtures on life cycle traits of a pelagic copepod

Multiple stressors like metal toxicity, organic compounds and sediment pollution from the Seine estuary are raising concern and novel toxicological approaches are needed to better assess and monitor the risk. In the present study, the copepod Eurytemora affinis from the Seine, was exposed to two different sources of contaminants, which were resuspended polluted sediments and a mixture of trace metals (dissolved phase). The exposure continued for four generations (F0, F1, F2, F3) where F0 is a generation for acclimation to the exposure condition and F3 is a generation for decontamination followed without any exposure, to detect possible maternal carryover effects of pollutants (F0 - F2) and the role of recovery (in F3). Higher accumulation of metals resulted in higher mortalities at both exposure conditions, with particularly F1 being the most sensitive generation showing highest bioaccumulation of metals, highest mortality, and smallest population size. Copper accumulation was highest of all metals in mixture from both the resuspended sediment and the combined trace metal treatment. A significantly lower naupliar production was seen in copepods exposed to resuspended sediment compared to trace metal exposed copepods. However, the decontamination phase (F3) indicated that E. affinis pre-exposed to resuspended sediment had a higher ability to recover the total population size, increase naupliar production, and depurate accumulated Cu. The population exposed to a trace metal mixture showed lower recovery and lower ability to discharge accumulated toxic metals indicating its greater effect on our experimental model when compared to resuspended sediment.

Cadmium sulfate induces apoptosis in planarians

With rapid socio-economic development, heavy metal pollution in water has become common and affects both environment and human health. Cadmium (Cd) has been recognized as one of the heavy metals which cause acute or chronic toxic effects if ingested. Although its toxicity is undisputed, the underlying molecular mechanisms in vivo are not fully understood. Planarians, a model organism famous for their regenerative prowess, have long been utilized to study the effects of chemical exposure. In this study, we observed apoptosis with TUNEL assay in planarians induced by cadmium sulfate (CdSO₄) in a dose-dependent manner. The apoptosis-related genes were detected with quantitative RT-PCR. Significant changes in c-Myc, P53, and BcL-2 were indicated, which may play a partial role in the regulation of the process of apoptosis in the planarians. H&E staining showed that Cd had obvious biological toxicity in the planarians. Here, new insights on metal toxicity mechanisms are provided, contributing to understand how CdSO₄ induces the pathological and physiological processes of apoptosis in the living bodies. Meanwhile, planarians are proved to be a freshwater pollution indicator and toxicological research model.

Mitigative effects of zinc on cadmium-induced reproductive toxicity in the male freshwater crab Sinopotamon henanense

Cadmium (Cd) is a highly harmful environmental contaminant, which can cause reproductive toxicity. Zinc (Zn) is an essential trance element that may protect the organism from the harmful effects of Cd. However, the mechanism of Zn against Cd-induced reproductive toxicity remained to be elucidated. The aim of this study was to assess the effects of subchronic exposure to Cd on the relative testis weight (RTW), the histopathology, the activity of stress marker antioxidant enzymes, the level of lipid peroxidation of testis, as well as the mitigative effects of Zn on Cd-induced reproductive toxicity in male freshwater crab Sinopotamon henanense. For this purpose, male crabs were divided into 10 groups including a control group (without metals) and metal exposure groups with Cd alone in three concentrations and Cd combined with Zn in six concentrations for 14 days. The results showed that Cd evoked concentration-dependent reproductive toxicity of male Sinopotamon henanense as showed by decreased RTW, appearance of morphological lesions, increased SOD, CAT, GPx activity, and MDA levels. Nevertheless, Zn combined with Cd exposure significantly alleviated Cd-induced reproductive toxicity as proved by increased RTW, reappearance of normal histological morphology, increased SOD activity, recovered CAT and GPx activity, and decreased MDA levels in testis. Our study demonstrated that the application of Zn can mitigate Cd-induced reproductive toxicity by ameliorating the testicular oxidative stress and improving the antioxidant status.

Logistic Regression Analysis Factors Affecting Sperm Motility and Abnormal Sperm Morphology in Boars

Simple Summary

Reduced sperm motility and morphological abnormalities have significant negative impacts on conception rates in sows and are important indexes of semen. The identification of factors that influence sperm motility and morphology will improve boar fertility in commercial herds. On the basis of analysis of 5042 ejaculates from 385 boars using a logistic regression model, we found that serum Cu excess, serum Fe deficiency, and Pb presence in seminal plasma were risk factors for poor semen quality in boars. More importantly, the presence of seminal plasma Pb had more serious effect on the probability of abnormal sperm morphology than serum Cu excess and serum Fe deficiency. In addition, Yorkshire and Landrace boars had higher sperm motility and lower abnormal sperm morphology than Duroc boars. The difference in serum and seminal plasma elements among boars with different semen qualities may become a guide for regulating these elements used in boar diet. The highly predictive values of serum Cu, Fe, and seminal plasma Pb could be used in the future as an additional tool in semen quality evaluation.

Abstract

Logistic regression models, including variables of boar breed, age, serum, and seminal plasma elements, were used to identify the influencing factors of sperm motility and morphology in this study. Sperm motility degree was classified as grade 0: ≤85% and grade 1: >85%. Abnormal sperm morphology was classified as grade 0: ≤10%, grade 1: 10–20%, and grade 2: >20%. Element concentration of 385 boars was detected by inductively coupled plasma mass spectrometry. Results showed that boars with serum Cu ≥ 2.5 mg/L had lower sperm motility (odds ratio (OR): 0.496; 95% confidence interval (CI): 0.285–0.864) and higher abnormal sperm morphology (OR: 2.003; 95% CI: 1.189–3.376) than those with serum Cu ≤ 2.0 mg/L. Boars with serum Fe ≥ 1.5 mg/L had lower abnormal sperm morphology than those with serum Fe ≤ 1.0 mg/L (OR: 0.463; 95% CI: 0.255–0.842). The presence of Pb in seminal plasma increased abnormal sperm morphology. The probability of abnormal sperm morphology >20% from boars with seminal plasma Pb increased with a range of 5.78–15.30% than that from boars without seminal plasma Pb among three breeds. In conclusion, serum Cu excess, serum Fe deficiency, and seminal plasma Pb are risk factors for poor semen quality in boars.

Identification and molecular characterization of peroxiredoxin 2 in grass carp (Ctenopharyngodon idella)

Peroxiredoxin (Prx), also named thioredoxin peroxidase (TPx), is a selenium independent antioxidant enzyme that can protect organisms from oxidative damage caused by reactive oxygen species (ROS) and is important for immune responses. In this study, the molecular cloning and characterization of a Prx2 homologue (CiPrx2) were described from grass carp (Ctenopharyngodon idella). The full-length cDNA of CiPrx2 was 1163 bp containing 5'-untranslated region (UTR) of 52 bp, a 3'-UTR of 517 bp with the putative polyadenylation consensus signal (AATAAA), an open reading frame (ORF) of 594 bp encoding polypeptides of 197 amino acids with a predicted molecular mass of 21.84 kDa and theoretical isoelectric point of 5.93. The analysis results of multiple sequence alignment and phylogenetic tree confirmed that CiPrx2 belong to the typical 2-Cys Prx subfamily. The CiPrx2 mRNA was ubiquitously expressed in all tested tissues. The temporal expression of CiPrx2 were differentially induced infected with grass carp reovirus (GCRV), polyinosinic:polycytidylic acid (poly I:C) and lipopolysaccharide (LPS) in liver and spleen. Subcellular localization of CiPrx2-GFP fusion proteins were only distributed in the cytoplasm. The purified recombinant CiPrx2 possessed an apparent antioxidant activity and could protect DNA against oxidative damage. Finally, CiPrx2 proteins could obviously inhibit H₂O₂ and heavy metal toxicity. However, further researches are needed to better understand the regulation of CiPrx2 under oxidative stresses.

Roles of three Es-Caspases during spermatogenesis and Cadmium-induced apoptosis in Eriocheir sinensis

Functions of Caspases remain obscure in Crustacea. We studied the existence and participations of apoptosis-related factors in Eriocheir sinensis testis. Three Es-Caspases (Es-Caspase 3/ 7/ 8) in E. sinensis were cloned and characterized. We observed that three es-caspases mRNA had specific expression patterns during spermiogenesis, with weak signal around the nucleus and invaginated acrosomal vesicle in early-stage spermatids, became stronger in middle-stage, finally focused on the acrosomal tube and nucleus in mature sperm. We then investigated the immunostaining intensity and positional alterations of Es-Caspase 3, Es-Caspase 8 and p53 during spermatogenesis, which were correlated with the differential tendencies of cells to undergo apoptosis and specific organelles shaping processes. After apoptotic induction by Cadmium, Es-Caspase 8 increased gradually, while Es-Caspase 3 increased firstly and then decreased, Es-p53 initially decreased and then increased. These results implies that Es-Caspase 3/ Es-Caspase 8/ p53 may play roles in Cadmium-induced apoptosis during spermatogenesis, and Caspase 8-Caspase 3-p53 pathway may interact with extrinsic or intrinsic pathways to regulate the destiny of sperm cells. Our study revealed the indispensable roles of Caspases during spermatogenesis and the possible molecular interactions in response to the Cadmium-induced apoptosis in E. sinensis, which filled the gap of apoptotic mechanisms of crustacean.

Serum and Seminal Plasma Element Concentrations in Relation to Semen Quality in Duroc Boars

Element concentrations in serum and seminal plasma were studied in Duroc boars with different semen quality characteristics. Based on the utilization rate of 2174 ejaculates from June to August in 2016, a total of 166 Duroc boars were allocated into three groups: low utilization rate group (LG, 0 to 60% utilization rate), medium utilization rate group (MG, 60 to 80%), and high utilization rate group (HG, 80 to 100%). Serum and seminal plasma samples were collected, and element levels were analyzed using inductively coupled plasma mass spectrometry. The results showed that LG boars had higher concentrations of serum copper and seminal plasma cadmium compared with MG and HG boars (P < 0.05), and serum copper and seminal plasma cadmium were negatively correlated with sperm motility, while positively correlated with the abnormal sperm rate. We observed the abnormal sperm rate increased by approximately 4.53% with serum copper increasing from 1.63 to 2.44 mg/L, while sperm motility decreased by approximately 2.85% with seminal plasma cadmium increasing from 0 to 0.82 μg/L. Moreover, serum iron and manganese levels in the LG group were significantly reduced compared with the HG boars (P < 0.05), and the two elements were negatively correlated with the abnormal sperm rate (P < 0.05). In conclusion, excessive copper and absence of iron and manganese in serum as well as higher seminal plasma cadmium may reduce the utilization rate of semen by impairing sperm motility and morphology, indicating the importance of adding and monitoring microelements in boar diet.

Trace metal distribution in crab organs and human health risk assessment on consumption of crabs collected from coastal water of South East coast of India

The concentrations of nine heavy metals accumulated in different organs of two crab species collected from the South East coast of India were estimated. The order of trace metal concentration in different organs of Portunus pelagicus was Cu > Mn > Cd > Ni > Pb > Co > Hg = Cr = U in gills, Cu > Mn > Cd > Ni > Pb = Co > Hg > Cr = U in hepatopancreas, and Cu > Cr > Ni > Mn > Cd > Pb > Co > Hg > U in muscles, whereas that for Portunus sanguinolentus was Cu > Mn > Cd > Ni > Pb > Co > Hg > Cr = U in gills, Cu > Mn > Cd > Ni > Pb = Co > U > Cr = Hg in hepatopancreas, and Cr > Cu > Ni > Mn > Cd > Co > Pb > Hg = U in muscles. The order of trace metal uptake for different organs was gills > hepatopancreas > muscles. Individual mean bioaccumulation index (IMBI) values varied between 0.0 and 0.52, 0.0 and 0.28, and 0.06 and 0.30 for gills, hepatopancreas, and muscles, respectively. Cr in muscles of P. sanguinolentus and Cu and Cd in all organs of both the species were found to be higher than the maximum permitted concentration recommended by food safety guidelines. Target hazard quotient (THQ) results suggested that there is a potential risk due to Co, Cd, and Cr, particularly for children, if the crab consumption frequency is more than once a month.

Effects of cadmium exposure on antioxidant enzymes and histological changes in the mud shrimp Austinogebia edulis (Crustacea: Decapoda)

The trace metal cadmium (Cd) is a toxic pollutant known to induce oxidative stress and other sublethal to lethal effects on aquatic organisms. We exposed the marine mud shrimp Austinogebia edulis to Cd concentrations of 0, 0.5, and 5 mg/kg for up to 4 days (24, 48, 72, 96 h). We studied the activity of antioxidant enzymes in the hepatopancreas, gill, and muscle of A. edulis. Antioxidant enzymes (SOD, CAT, and GPx) decreased with increasing Cd concentration and extended exposure time in these three organs of the mud shrimp A. edulis. Increasing Cd concentration led to an increase in ROS and resulted ultimately in membrane lipid peroxidation at higher Cd concentrations. Significant damage of the hepatopancreas of A. edulis was noticed at higher concentrations of Cd, showing damages like the disappearance of epithelial cell boundaries, detachment of cells from the basal lamina, cellular swelling, necrosis, and reduction of glycogen. In conclusion, Cd caused oxidative damage by reducing the activities of antioxidant enzymes and by damaging the tissue structure in major organs of the mud shrimp A. edulis.

Biochemical and Molecular Bases of Lead-Induced Toxicity in Mammalian Systems and Possible Mitigations

The effects of lead exposure on mammals are reported to be devastating. Lead is present in all the abiotic environmental components such as brass, dust, plumbing fixtures, soil, water, and lead mixed imported products. Its continuous use for several industrial and domestic purposes has caused a rise in its levels, thereby posing serious threats to human health. The mechanisms involved in lead-induced toxicity primarily include free-radical-mediated generation of oxidative stress which directly imbalances the prooxidants and the antioxidants in body. The toxicity of lead involves damage primarily to major biomolecules (lipid, protein, and nucleic acids) and liver (hepatotoxicity), nervous system (neurotoxicity), kidney (nephrotoxicity) and DNA (genotoxicity), present in animals and humans. The activation of c-Jun NH2-terminal kinase, phosphoinositide 3-kinase, or Akt and p38 mitogen activated protein kinase signaling pathways are important for lead cytotoxicity. Lead increased apoptosis through signaling cascade and associated factors and significantly impairs cell differentiation and maturation. In addition, lead has great impact on metabolic pathways such as heme synthesis, thereby leading to the onset of anemia in lead exposed people. This review encompasses an updated account of varied aspects of lead-induced oxidative stress and the biomolecular consequences such as perturbations in physiological processes, apoptosis, carcinogenesis, hormonal imbalance, loss of vision, and reduced fertility and their possible remediation through synthetic (chelators) and natural compounds (plant-based principles). This paper is primarily concerned with the biomedical implications of lead-induced generation of free radical and the toxicity management in the mammalian system.

Pike intestinal reaction to Acanthocephalus lucii (Acanthocephala): immunohistochemical and ultrastructural surveys

Background

The Northern pike, Esox lucius, is a large, long-lived, top-predator fish species and occupies a broad range of aquatic environments. This species is on its way to becoming an important model organism and has the potential to contribute new knowledge and a better understanding of ecology and evolutionary biology. Very few studies have been done on the intestinal pathology of pike infected with helminths. The present study details the first Italian record of adult Acanthocephalus lucii reported in the intestine of E. lucius.

Results

A total of 22 pike from Lake Piediluco (Central Italy) were examined, of which 16 (72.7%) were infected with A. lucii. The most affected areas of gastrointestinal tract were the medium and distal intestine. The intensity of infection ranged from 1 to 18 parasites per host. Acanthocephalus lucii penetrated mucosal and submucosal layers which had a high number of mast cells (MCs) with an intense degranulation. The cellular elements involved in the immune response within the intestine of pike were assessed by ultrastructural techniques and immunohistochemistry using antibodies against met-enkephalin, immunoglobulin E (IgE)-like receptor (FCεRIγ), histamine, interleukin-6, interleukin-1β, substance P, lysozyme, serotonin, inducible-nitric oxide synthase (i-NOS), tumor necrosis factor-α (TNF-α) and the antimicrobial peptide piscidin 3 (P3). In intestines of the pike, several MCs were immunopositive to 9 out of the 11 aforementioned antibodies and infected fish had a higher number of positive MCs when compared to uninfected fish.

Conclusions

Pike intestinal tissue response to A. lucii was documented. Numerous MCs were seen throughout the mucosa and submucosal layers. In infected and uninfected intestines of pike, MCs were the dominant immune cell type encountered; they are the most common granulocyte type involved in several fish-helminth systems. Immunopositivity of MCs to 9 out of 11 antibodies is of great interest and these cells could play an important key role in the host response to an enteric helminth. This is the first report of A. lucii in an Italian population of E. lucius and the first account on positivity of MCs to piscidin 3 and histamine in a non-perciform fish.

Bisphenol A-induced ultrastructural changes in the testes of common marmoset

Background & objectives:

Bisphenol A (BPA) is an endocrine disruptor that is widely used in the manufacture of polycarbonate plastics, epoxy resins and dental sealants. It is known to have adverse effects on spermatogenesis in rodents. This study was aimed to evaluate the effects of BPA in adult common marmoset owing to its similarities with human spermatogenesis.

Methods:

Sixteen marmosets were divided into four groups (n=4 per group) and given oral doses of BPA (2.5, 12.5 and 25 μg/kg BW/day) for 70 days to cover two spermatogenic cycles, and the control group received only vehicle (honey). Testes were processed for histological and transmission electron microscopy studies.

Results:

Histology of the testis showed sloughing of germ cells into the lumen, increase in interstitial space and vacuolation of Sertoli cell cytoplasm. Ultrastructural analysis of the testis revealed several degenerative effects on the basement membrane, Sertoli cells, Leydig cells and other developing germ cells in the 12.5 and 25 μg/kg BW/day groups as compared to control.

Interpretation & conclusions:

The observed ultrastructural changes caused by BPA in testicular morphology might be indicative of a perturbed sperm production. Considering the genetic and spermatogenic similarities of common marmoset (Callithrix jacchus) and humans, the study findings are of significance. Further studies are, however, needed to elucidate the mechanism of action.

Oral administration of cadmium depletes intratesticular and epididymal iron levels and inhibits lipid peroxidation in the testis and epididymis of adult rats

Cadmium (Cd)-induced tissue injury depends on the accumulated Cd which differentially affects endogenous iron (Fe). To investigate this, adult rats were treated by oral gavage with Cd (50 mg/kg body wt.) once a week for 15, 30 and 60 days and sacrificed a day after last administration. After the 15th and 30th day of treatment, Cd had no effect on thiobarbituric acid reactive substances (TBARS) and endogenous Fe levels but exhibited anti-androgenic effects (p < 0.05) and caused histological damages. At day 60, Cd was accumulated by 156.30% and 364.77% above control values at concentrations that decreased endogenous Fe levels by 46.41% and 50.31% in the testis and epididymis respectively. The histological damages were characterized by decreased tubular diameter, damage to the epithelium leading to loss of tubular germ cells and absent of spermatozoa in the epididymal lumen. Although myeloperoxidase activities were increased, TBARS levels were found to decrease significantly at day 60 in the serum, testis and epididymis suggesting that the histological damages were not caused by lipid peroxidation. Furthermore, TBARS correlated negatively with Cd in the testis (r = -0.251, p < 0.05) and epididymis (r = -0.286, p < 0.05); Fe correlated positively with TBARS in the testis (r = +0.217, p < 0.05) and Cd correlated negatively with Fe in the testis (r = -0.461, p < 0.05) and epididymis (r = -0.109, p < 0.05). The antioxidant enzymes, superoxide dismutase and glutathione peroxidase were also decreased in the gonads after 60 days Cd treatment. Overall, anti-androgenic effects and histo-pathological changes are early indicators of direct effects of Cd and occur before decrease in TBARS which is secondarily related to the modifying of Fe contents.

Identification and functional analysis of inhibitor of NF-κB kinase (IKK) from Scylla paramamosain: The first evidence of three IKKs in crab species and their expression profiles under biotic and abiotic stresses

IKK (inhibitor of NF-κB kinase) is the critical regulator for NF-κB (nuclear factor-κB) pathway against pathogenic invasion in vertebrates or invertebrates. However, the IKK from crab species has not yet been identified. In the present study, three full-length cDNA sequences of IKKs from mud crab Scylla paramamosain, designated as SpIKKβ, SpIKKε1 and SpIKKε2, were firstly cloned through RT-PCR and RACE methods. This is also the first report about the identification of two IKKε genes in mud crab and even in crustaceans. The SpIKKβ cDNA was 2824 bp in length with an open reading frame (ORF) of 2382 bp, which encoded a putative protein of 793 amino acids (aa). The ORF of two SpIKKε isoforms, SpIKKε1 and SpIKKε2, were 2400 bp and 2331 bp in length encoding 799 aa and 776 aa, respectively. The crucial conserved residues and functional domains, including the kinase domains (KDs) and leucine zipper (LZ), were identified in all SpIKKs. Phylogenetic analysis suggested that SpIKKβ was classified into the IKKs class while SpIKKεs could be grouped into the IKK-related kinases class. The qRT-PCR analysis showed that three SpIKKs were constitutively expressed in all tested tissues and the highest expression levels of SpIKKβ and SpIKKεs were all in hemocyte. The gene expression profiles of SpIKKs were distinct when crabs suffered biotic and abiotic stresses including the exposures of Vibrio alginolyticus, poly (I:C), cadmium and air exposure, suggesting that the SpIKKs might play different roles in response to pathogens infections, heavy metal and air exposure. Moreover, IKKs from mud crab can significantly activate mammalian NF-κB pathway, suggesting the function of IKKs might be evolutionally well-conserved. Results of the RNAi experiments suggested that SpIKKs might regulate the immune signaling pathway when hemocytes were challenged with V. parahemolyticus or virus-analog poly (I:C). All of these results indicated that the obtained SpIKKs might be involved in stress responses against biotic or abiotic stresses, and it also highlighted their functional conservation in the innate immune system from crustaceans to mammals.

Hydrogen peroxide-induced oxidative stress, acetylcholinesterase inhibition, and mediated brain injury attenuated by Thymus algeriensis

The aim of the current study was to evaluate acetylcholinesterase (AChE) inhibition, antioxidant enzyme activities, and malondialdehyde (MDA) levels induced by hydrophobic fractions of Thymus algeriensis (HFTS) growing in Tunisia. The results showed that hydrogen peroxide (H₂O₂), an oxidative stress inducer, acts by decreasing the body mass and brain mass of rats. Moreover, we found higher MDA levels in the group treated with H₂O₂ (P < 0.05) and a significantly lower activity of catalase, glutathione peroxidase, glutathione S-transferase, and superoxide dismutase, as well as a reduction in reduced glutathione activity in the brain tissues of H₂O₂-treated rats when compared with those of the control group (P < 0.05); however, rats that received HFTS with H₂O₂ experienced a decrease in MDA levels in the brain. In contrast, HFTS demonstrated neuroprotective effects in rat brain. Overall, exposure to HFTS prior to H₂O₂ induced a marked dose-dependent increase in reactive oxygen species scavenger levels (P < 0.05) accompanied by a statistically significant decrease in MDA levels (P < 0.05) when compared with no exposure. Notably, the activity of AChE was affected by exposure to natural compounds; levels were significantly lower in HFTS-treated rats and in those treated with the combination of HFTS and a low or high dose of H₂O₂. Furthermore, histopathological analysis showed that brain injuries occurred with high doses of H₂O₂ administered alone or with a low dose of HFTS, whereas a high dose of essential oil markedly alleviated neurone degeneration. The results suggest that HFTS alleviates neuroinflammation by acting as an AChE inhibitor and attenuates H₂O₂-induced brain toxicity.

Identification and characterization of six peroxiredoxin transcripts from mud crab Scylla paramamosain: The first evidence of peroxiredoxin gene family in crustacean and their expression profiles under biotic and abiotic stresses

The peroxiredoxins (Prxs) define a novel and evolutionarily conserved superfamily of peroxidases able to protect cells from oxidative damage by catalyzing the reduction of a wide range of cellular peroxides. Prxs have been identified in prokaryotes as well as in eukaryotes, however, the composition and number of Prxs family members vary in different species. In this study, six Prxs were firstly identified from the mud crab Scylla paramamosain by RT-PCR and RACE methods. Six SpPrxs can be subdivided into three classes: (a) three typical 2-Cys enzymes denominated as Prx1/2, 3, 4, (b) two atypical 2-Cys enzymes known as Prx5-1 and Prx5-2, and (c) a 1-Cys isoform named Prx6. The evolutionarily conserved signatures of peroxiredoxin catalytic center were identified in all six SpPrxs. Phylogenetic analysis revealed that SpPrx3, SpPrx4, SpPrx5s and SpPrx6 were clearly classified into Prx3-6 subclasses, respectively. Although SpPrx1/2 could not be grouped into any known Prx subclasses, SpPrx1/2 clustered together with other arthropods Prx1 or unclassified Prx and could be classified into the typical 2-Cys class. The comparative and evolutionary analysis of the Prx gene family in invertebrates and vertebrates were also conducted for the first time. Tissue-specific expression analysis revealed that these six SpPrxs were expressed in different transcription patterns while the highest expression levels were almost all in the hepatopancreas. Quantitative RT-PCR analysis exhibited that the gene expression profiles of six SpPrxs were distinct when crabs suffered biotic and abiotic stresses including the exposures of Vibrio alginolyticus, poly (I:C), cadmium and hypoosmotic salinity, suggesting that the SpPrxs might play different roles in response to various stresses. The recombinant proteins including the SpPrx1/2, SpPrx4, SpPrx5-1 and SpPrx6 were purified and the peroxidase activity assays indicated that all these proteins can reduce H₂O₂ in a typical DTT-dependent manner. To our knowledge, this is the first study about the comprehensive characterization of Prx gene family in Scylla paramamosain and even in crustaceans. These results would broaden the current knowledge of the whole Prx family as well as be helpful to understand and clarify the evolutionary pattern of Prx family in invertebrate and vertebrate taxa.

Effects of exposure to multiple heavy metals on biochemical and histopathological alterations in common carp, Cyprinus carpio L

Heavy metals are frequently encountered as mixtures of essential and non-essential elements. Therefore, evaluation of their toxic effects individually does not offer a realistic estimate of their impact on biological processes. We studied effects of exposure to mixtures of essential and toxic metals (Cr, Cd and Pb) on biochemical, immunotoxicity level and morphological characteristics of the various tissues of a biomarker freshwater fish common carp using environmentally relevant concentrations. Fish were exposed to metal mixture through tank water for 7, 15 and 30 days, under controlled laboratory conditions. Tissue accumulation of the metals was measured using Atomic Absorption Spectrophotometric techniques. Chromium, cadmium and lead accumulation in muscle, gills, liver, kidney and intestine, tissue of common carp exposed to mixture metals for 30 days increased significant compared with control group (p < 0.001). However, the activity of antioxidant enzymes such as catalase (CAT) and superoxide dismutase (SOD) levels was significant altered in various tissues of exposed fish. Besides, the lipid peroxidation (LPO) was significant (p < 0.001) increased. Moreover, the tumor necrosis factor - α (TNF-α), interleukin (IL-6), and interferon-γ (IFN-γ) contents in tissues of muscle, gills, liver, kidney and intestine were increased significant compared with control fish (p < 0.001). In addition, microscopic examination of the main alterations in general morphology of fish gills included spiking and fusion of secondary lamellae, formation of club-shaped filaments epithelium in the interlamellar regions and hepatocytes showed damage of central vein and rupture of irregular hepatic plate with more number of vacuoles in the fish exposed to metal mixture for a longer duration (30 days). These results of this study clearly demonstrate that concentration individual and mixtures of metals in aquatic systems will greatly influence the cytokine alterations may result in an immune suppression or excessive activation in the treated common carp as well as may cause immune dysfunction or reduced immunity. In conclusion, toxicity of multiple metal mixtures of Cr, Cd and Pb has antioxidant and immunotoxic effects on C. carpio.

Cell damage and apoptosis in the hepatopancreas of Eriocheir sinensis induced by cadmium

Cadmium (Cd) is one of the most common pollutants in the environment and it is known to cause a range of tissue damages and apoptosis in invertebrates. In this study, we investigated the effect of Cd on the hepatopancreas of the crab Eriocheir sinensis, a commercially and ecologically important species of crustacean. The crabs were first exposed to water containing different concentrations of Cd²⁺ (0, 0.63, 1.26, 2.52, 5.04 and 10.07mg/L) for 6days. Typical morphological characteristics and physiological changes of apoptosis were then observed using various methods, including AO/EB double fluorescence staining, transmission electron microscopy and DNA fragmentation analysis. The results showed that Cd²⁺ induced cell damage and apoptosis in a concentration-dependent manner. Transmission electron microscopy revealed the presence of cellular swelling and necrosis with reduced number of microvilli on the cell surface and damages to individual organelles. The mitochondria became swollen and vacuolated. The rough endoplasmic reticulum (Rer) was expanded, with membrane rupture and many different sizes of vesicles, suggesting the destruction of protein-synthesizing structures in the hepatopancreatic cells. The activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidases (GPx) initially increased and subsequently decreased with increasing Cd²⁺ concentrations. This was accompanied by increases in malondialdehyde (MDA) and H₂O₂ contents, which led to membrane lipid peroxidation. Crabs exposed to Cd²⁺ also displayed significant increases in caspase-3, -8, and -9 activities compared to control crabs. Cadmium induced the production and accumulation of ROS in the hepatopancreas, which resulted in oxidative damage and abnormal metabolism. Taken together, the results indicated that Cd²⁺ could induce oxidative damage as well caspase-dependent apoptosis in E. sinensis hepatopancreas.

The environment and male reproduction: The effect of cadmium exposure on reproductive function and its implication in fertility

Cadmium is an environmental pollutant known as endocrine disruptor. Testis is particularly susceptible to cadmium, and testis injury occurs at high but even low levels of exposure. Cadmium reproductive toxicity is mediated by multiple mechanisms, including structural damage to testis vasculature and blood-testis barrier, inflammation, cytotoxicity on Sertoli and Leydig cells, oxidative stress mainly by means of mimicry and interference with essential ions, apoptosis, interference with selected signaling pathways and epigenetic regulation of genes involved in the regulation of reproductive function, and disturbance of the hypothalamus-pituitary-gonadal axis. The current review outlines epidemiological observational findings from environmental and occupational exposure in humans, and reports experimental studies in humans and animals. Lastly, a focus on the pathogenetic mechanisms of cadmium toxicity and on the specific mechanisms of cadmium sensitivity and resistance, particularly assessed in animal models, is included. Despite convincing experimental findings in animals and supporting evidences in humans identifying cadmium as reproductive toxicant, observational findings are controversial, suffering from heterogeneity of study design and pattern of exposure, and from co-exposure to multiple pollutants.

Bisphenol A-induced ultrastructural changes in the testes of common marmoset

BACKGROUND & OBJECTIVES

Bisphenol A (BPA) is an endocrine disruptor that is widely used in the manufacture of polycarbonate plastics, epoxy resins and dental sealants. It is known to have adverse effects on spermatogenesis in rodents. This study was aimed to evaluate the effects of BPA in adult common marmoset owing to its similarities with human spermatogenesis.

METHODS

Sixteen marmosets were divided into four groups (n=4 per group) and given oral doses of BPA (2.5, 12.5 and 25 μg/kg BW/day) for 70 days to cover two spermatogenic cycles, and the control group received only vehicle (honey). Testes were processed for histological and transmission electron microscopy studies.

RESULTS

Histology of the testis showed sloughing of germ cells into the lumen, increase in interstitial space and vacuolation of Sertoli cell cytoplasm. Ultrastructural analysis of the testis revealed several degenerative effects on the basement membrane, Sertoli cells, Leydig cells and other developing germ cells in the 12.5 and 25 μg/kg BW/day groups as compared to control.

INTERPRETATION & CONCLUSIONS

The observed ultrastructural changes caused by BPA in testicular morphology might be indicative of a perturbed sperm production. Considering the genetic and spermatogenic similarities of common marmoset (Callithrix jacchus) and humans, the study findings are of significance. Further studies are, however, needed to elucidate the mechanism of action.

Grape juice concentrate alleviates epididymis and sperm damage in cadmium-intoxicated rats

The possibility of long-term grape juice concentrate (GJC) consumption conferring a protective effect against cadmium (Cd)-induced damage to the epididymis, completely preserving sperm profile, was evaluated here for the first time in the scientific literature. Male Wistar rats (n = 6/per group) received an intraperitoneal Cd injection (1.2 mg/Kg) at age 80 days and GJC (2 g/Kg) by gavage from 50 days until 136 days old. Groups receiving either Cd or GJC were added. An intraperitoneal injection of saline (0.9%) and water by gavage was administered in the absence of treatment with Cd or GJC. Animals were anaesthetized and exsanguinated at 136 days; the vas deferens, left testis and epididymis were removed; and perfusion continued with fixative. The right epididymis was collected for morphological analysis. Cd had a devastating effect demonstrated by reduced sperm count in testes and epididymis, sperm production and normal sperm count, besides increased epididymis sperm transit time and completely disorganized morphology. These alterations were attributed to higher Cd levels in the testes and a lipid peroxidation (LP) process. Consumption of GJC plus Cd intoxication was effective, reducing metal accumulation and LP. Consequently, we could identify a preserved sperm profile, with improvement in testis and epididymis sperm count, normal sperm structure and sperm transit time. Moreover, GJC extends its protective effect to the epididymis, allowing complete re-establishment of its morphology, ensuring successful sperm maturation process. In conclusion, our study indicates long-term GJC as a promising therapy against reproductive chemical intoxication injury damage, preserving sperm prior to ejaculation.

Sulforaphane Prevents Testicular Damage in Kunming Mice Exposed to Cadmium via Activation of Nrf2/ARE Signaling Pathways

Sulforaphane (SFN) is a natural and highly effective antioxidant. Studies suggest that SFN protects cells and tissues against cadmium (Cd) toxicity. This study investigated the protective effect of SFN against oxidative damage in the testes of Kunming mice exposed to cadmium, and explored the possible molecular mechanisms involved. Cadmium greatly reduced the serum testosterone levels in mice, reduced sperm motility, total sperm count, and increased the sperm deformity rate. Cadmium also reduces superoxide dismutase (T-SOD) and glutathione (GSH) levels and increases malondialdehyde (MDA) concentrations. SFN intervention improved sperm quality, serum testosterone, and antioxidant levels. Both mRNA and protein expression of mouse testicular nuclear factor-erythroid 2-related factor 2 (Nrf2) was reduced in cadmium-treated group. Furthermore, the downstream genes of Nrf2, glutathione peroxidase (GSH-Px), γ-glutamyl cysteine synthetase (γ-GCS), heme oxygenase-1 (HO-1), and NAD(P)H:quinone oxidoreductase-1 (NQO1) were also decreased in cadmium-treated group. SFN intervention increases the expression of these genes. Sulforaphane prevents cadmium-induced testicular damage, probably via activation of Nrf2/ARE signaling.

Quality decline and oxidative damage in sperm of freshwater crab Sinopotamon henanense exposed to lead

Lead (Pb) induces male infertility in vertebrates. Whether lead is related to reproductive abnormalities in aquatic invertebrates remains uncertain. In this work, effects of Pb on the sperm quality and oxidative stress of the freshwater crab Sinopotamon henanense were investigated after 3, 5 and 7d exposure to different Pb concentrations (0, 3.675, 7.35, 14.7, 29.4 and 58.8mg/L). Sperm quality indices including sperm plasma-membrane integrity and acrosomal-membrane integrity were measured by flow cytometry. DNA integrity was measured by fluorescence microscopy. The results showed that Pb levels in sperm increased significantly upon Pb exposure in most treated groups, sperm plasma-membrane integrity, acrosomal-membrane integrity, and DNA integrity were reduced at higher concentrations after 5 d and 7d. Oxidative stress of sperm induced by Pb was reflected in significant up-regulation of reactive oxygen species (ROS) levels after 3, 5 and 7d. A significant reduction of the total antioxidant capacity levels occurred after exposure to 14.7mg/L Pb and above at 7d compared to the control. The results of oxidative damage to lipids, proteins and DNA of sperm showed that malondialdehyde, protein carbonylation and DNA-protein crosslinks were increased in a concentration- and time-dependent manner. Our findings document that Pb can induce harmful effects on several reproductive endpoints in a freshwater crab.

Immune-associated parameters and antioxidative responses to cadmium in the freshwater crab Sinopotamon henanense

Cadmium (Cd) is a toxic heavy metal pollutant and is known to exert adverse effects in organisms. In this study, we examined immune-related and antioxidative parameters in crabs exposed to sublethal levels of Cd. The results showed that Cd exposure elicited a significant accumulation in hemolymph, a decrease in total hemocyte counts, and the production of reactive oxygen species (ROS). Cd treatment also upregulated activities of antioxidant enzymes including superoxide dismutase, catalase, and glutathione peroxidase in the hemocytes of crabs. Treatment with Cd further decreased the stability of lysosomal membranes in hemocytes and induced substantial changes of immune-related parameters including acid phosphatase and alkaline phosphatase. However, the activity of lysozyme varied weakly throughout the Cd treatment period. Our results suggest that Cd exposure caused immunomodulation, a potentially harmful immunity function and damage in the antioxidant system of Sinopotamon henanense.

Cadmium induced oxidative damage and apoptosis in the hepatopancreas of Meretrix meretrix

Even trace amounts of cadmium (Cd), a non-essential metal, are known to be toxic to aquatic organisms. Here we investigated the relationship between cadmium ion (Cd(2+)) exposure and oxidative damage and apoptosis in the hepatopancreas of the clam Meretrix meretrix. Clams were exposed to different concentrations of Cd(2+) (0, 1.5, 3, 6 and 12 mg L(-1)) for 5 days. We monitored both antioxidant enzyme activity, including that of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidases (GPx), and levels of malondialdehyde (MDA), glutathione (GSH) and glutathione disulfide (GSSG). Apoptosis of hepatopancreatic cells was detected by DNA laddering and AO/EB double fluorescent staining. The results show that the rate of apoptotis, MDA levels, and caspase-3 activity, increased with Cd(2+) concentration, whereas GPx activity and the ratio of GSH/GSSG, decreased. SOD and CAT enzyme activity first increased, then decreased, with increasing Cd(2+) concentration; peak activity of these enzymes was recorded in the 3 mg L(-1) Cd(2+)-treatment group. These results show that Cd-induced oxidative damage can both induce, and aggravate, apoptosis in the hepatopancreatic cells of clams, even at Cd(2+) concentrations far below the semi-lethal dose for adult clams. The observed changes in caspase-3 activity enhanced significantly at lower Cd(2+) concentrations, indicating that caspase-3 is a suitable biomarker for heavy metal pollution, especially cadmium pollution, in marine organisms.

Oxidative stress and spermatogenesis suppression in the testis of cadmium-treated Bombyx mori larvae

Bombyx mori L. (B. mori) were exposed to cadmium chloride (CdCl2) incorporated in an artificial diet (0, 6.25, 12.5, 25, and 50 mg kg(-1)) throughout the larval stage. Changes in malondialdehyde (MDA) and reduced glutathione (GSH) contents and activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px), as well as their corresponding messenger RNA (mRNA) levels in the testes of the fifth instar larvae were evaluated. Additionally, spermatozoon deformation in the testes was examined. Upon Cd treatment, the MDA content in the testes was significantly increased in a concentration-dependent manner. Cd-exposed larvae had increased levels of glutathione. Pearson's correlation analysis revealed that SOD and CAT activities were positively correlated (R (2) = 0.605, P = 0.017). The changing trends in the mRNA levels of these enzymes were not always consistent with those of enzymatic activities. Alterations in GSH-Px activities and mRNA levels were positively correlated (R (2) = 0.771, P < 0.01). Morphological analysis revealed that Cd deformed and affected the maturation of spermatozoa. Our results collectively support a relationship between Cd and alterations in the levels of antioxidant enzymes in B. mori testes.

Transcriptome assembly and expression profiling of molecular responses to cadmium toxicity in hepatopancreas of the freshwater crab Sinopotamon henanense

Cadmium (Cd) pollution is a serious global problem, which causes irreversible toxic effects on animals. Freshwater crab, Sinopotamon henanense, is a useful environmental indicator since it is widely distributed in benthic habitats whereby it tends to accumulate Cd and other toxicants. However, its molecular responses to Cd toxicity remain unclear. In this study, we performed transcriptome sequencing and gene expression analyses of its hepatopancreas with and without Cd treatments. A total of 7.78 G clean reads were obtained from the pooled samples, and 68,648 unigenes with an average size of 622 bp were assembled, in which 5,436 were metabolism-associated and 2,728 were stimulus response-associated that include 380 immunity-related unigenes. Expression profile analysis demonstrated that most genes involved in macromolecular metabolism, oxidative phosphorylation, detoxification and anti-oxidant defense were up-regulated by Cd exposure, whereas immunity-related genes were down-regulated, except the genes involved in phagocytosis were up-regulated. The current data indicate that Cd exposure alters gene expressions in a concentration-dependent manner. Therefore, our results provide the first comprehensive S.henanense transcriptome dataset, which is useful for biological and ecotoxicological studies on this crab and its related species at molecular level, and some key Cd-responsive genes may provide candidate biomarkers for monitoring aquatic pollution by heavy metals.