Unravelling the Role of Metallothionein on Development, Reproduction and Detoxification in the Wall Lizard Podarcis sicula

Variability in maternal transfer efficiency of trace elements in green turtles (Chelonia mydas)

The transfer of trace elements (TEs) from female sea turtles to their eggs is crucial in providing essential nutrition for embryonic development, while also posing a potential risk of pollutant exposure. This study aimed to quantify the concentrations of TEs in the claws and epidermis of nesting females, as well as in egg contents and embryos, and to investigate the migration of TEs during the maternal transfer in green turtles. The findings revealed that the maternal transfer coefficients for essential elements including Fe, Cu, and Zn (excluding those derived from accumulated tissue) ranged from 1.0 to 10.0, while the coefficients for non-essential elements such as Cd, As, and Hg were found to be below 1.0. During embryonic development, the migration coefficients of Fe, Mn, Ni, Zn and Sr exhibited a progressive increase, reaching their peak at stages 27-31 with values of 9.14 for Fe, 6.52 for Mn, 6.34 for Ni, 2.90 for Zn, and 2.66 for Sr. This indicates a high efficiency in the assimilation of these elements. Conversely, the migration coefficients of Cu, Se, Cd, Pb, and Hg declined rapidly after peaking at stages 19-22. Additionally, the kidneys of final-stage embryos and hatchlings exhibited significantly higher levels of non-essential elements compared to other tissues, while the liver displayed higher concentrations of Cu. These results suggest that early-stage embryos are particularly vulnerable to the adverse effects of non-essential or excessive essential elements, and as well, they indicate the presence of potential detoxification mechanisms that may develop following tissue and organ formation, which warrants further investigation.

Ferroptosis is involved in polymyxin B-induced acute kidney injury via activation of p53

Polymyxin B (PMB) is one of the most effective drugs for the treatment of multi-resistant and pan-resistant gram-negative infections. However, it can induce acute kidney injury (AKI), the mechanism of which has not yet been fully elucidated. In this study, RNA sequencing and in vitro and in vivo experiments demonstrated that PMB induced AKI by promoting ferroptosis. Moreover, the metallothionein-1 (MT-1) level was significantly increased in the AKI group and clinical cases revealed that iron and MT-1 levels in urine were significantly higher in patients with AKI than in those without AKI. To explore the mechanism of PMB induced ferroptosis, we silenced p53 in human kidney-2 (HK2) cells according to RNA sequencing, which showed that p53 was obviously enhanced in the PMB treated group. While PMB significantly enhanced Fe²⁺, lipid peroxidation, malondialdehyde (MDA), transferrin receptor protein 1 (TFR1), and arachidonate 12-lpoxygenase (ALOX12), decreased the survival rate, solute carrier family 7 member 11 (SLC7A11), glutathione peroxidase 4 (GPX4), and glutathione (GSH), downregulation of p53 reversed these effects, suggesting PMB induced ferroptosis by activating p53. Studies have shown p53 can promote ferroptosis by regulating the downstream factors SLC7A11 or TFR1. Further, we verified that silencing TFR1 expression as well as overexpression of SLC7A11 inhibited ferroptosis and significantly increased the survival rate of HK2 cells. Overall, PMB induces ferroptosis in renal tubular cells by activating p53 to reduce SLC7A11 expression and elevate TFR1, leading to AKI; MT-1 and iron levels in urine were significantly increased when PMB induced ferroptosis.

Metallothionein gene expression in rat tissues: response to dietary restriction after orally dichlorodiphenyldichloroethylene (DDE) exposure and high-fat feeding

Dichlorodiphenyldichloroethylene (DDE) is an environmental pollutant that accumulates in adipose tissue through the food chain. Hypercaloric, high-fat diet is considered to promote the accumulation of toxic lipophilic substances in tissues, whereas the loss of body fat through caloric restriction results in a recirculation of these substances. In rats, oral administration of DDE causes the onset of tissues damage; the concomitant intake of a high-fat diet ameliorates tissues status, probably because of the entrapment of the lipophilic substance in fat depots. Recent evidence demonstrates that DDE alters the expression of metallothioneins, proteins involved in cellular defense from oxidative stress, in a diet- and tissue-specific manner. This study is aimed to verify if 2 weeks of caloric restriction after the oral DDE treatment can modify metallothionein gene expression in tissues of high-fat fed rats. Real-time PCR analysis demonstrates that metallothionein gene expression after calorie restriction is tissue-specific and strongly influenced by both previous dietary conditions and DDE exposure. To avoid misleading conclusions on the interference of toxic xenobiotics on metallothionein gene expression is particularly important to consider the tissue, the cellular conditions, and the nutritional status of the animals, especially when the protein is used as an index of cells health.

Molecular and Histological Effects of Glyphosate on Testicular Tissue of the Lizard Podarcis siculus

The expansion of agriculture produces a steady increase in habitat fragmentation and degradation due to the increased use of pesticides and herbicides. Habitat loss and alteration associated with crop production play an important role in reptile decline, among which lizards are particularly endangered. In this study, we evaluated testicular structure, steroidogenesis, and estrogen receptor expression/localization after three weeks of oral exposure to glyphosate at 0.05 and 0.5 μg/kg body weight every other day in the field lizard Podarcis siculus. Our results show that glyphosate affected testicular morphology, reduced spermatogenesis, altered gap junctions and changed the localization of estrogen receptors in germ cells, increasing their expression; the effects were mostly dose-dependent. The result also demonstrates that glyphosate, at least at these concentrations, did not influence steroidogenesis. Overall, the data indicate that this herbicide can disturb the morphophysiology of the male lizard's reproductive system, with obviously detrimental effects on their reproductive fitness. The effects of glyphosate must be considered biologically relevant and could endanger the reproductive capacity not only of lizards but also of other vertebrates, including humans; a more controlled and less intensive use of glyphosate in areas devoted to crop production would therefore be advisable.

Stress response markers in the blood of São Tomé green sea turtles (Chelonia mydas) and their relation with accumulated metal levels

Metals are persistent worldwide being harmful for diverse organisms and having complex and combined effects with other contaminants in the environment. Sea turtles accumulate these contaminants being considered good bioindicator species for marine pollution. However, very little is known on how this is affecting these charismatic animals. São Tomé and Príncipe archipelago harbours important green sea turtle (Chelonia mydas) nesting and feeding grounds. The main goal of this study was to determine metal and metalloid accumulation in the blood of females C. mydas nesting in São Tomé Island, and evaluate the possible impacts of this contamination by addressing molecular stress responses. Gene expression analysis was performed in blood targeting genes involved in detoxification/sequestration and metal transport (mt, mtf and fer), and in antioxidant and oxidative stress responses (cat, sod, gr, tdx, txrd, selp and gclc). Micronuclei analysis in blood was also addressed as a biomarker of genotoxicity. Present results showed significant correlations between different gene expressions with the metals evaluated. The best GLM models and significant relationships were found for mt expression, for which 78% of the variability was attributed to metal levels (Al, Cu, Fe, Hg, Pb and Zn), followed by micronuclei count (65% - Cr, Cu, Fe, Hg, Mn and Zn), tdx expression (52% - Cd, Fe, Mn, Pb and Se), and cat expression (52% - As, Fe, Se and Cd x Hg). Overall, this study demonstrates that these green sea turtles are trying to adapt to the oxidative stress and damage produced by metals through the increased expression of antioxidants and other protectors, which raises concerns about the impacts on these endangered organisms' fitness. Furthermore, promising biomarker candidates associated to metal stress were identified in this species that may be used in future biomonitoring studies using C. mydas' blood, allowing for a temporal follow-up of the organisms.

Environmental biomonitoring by snails

Background: Bio-indicator systems are vital in terms of monitoring of pollutants around the world. The impact of environmental change can be monitored by employing the responsive behaviour of snails. Heavy metal and organic pollutants affects snail reproduction, mortality, and normal metabolic activities. Various changes like a discontinuity in food intake, growth rate, twitching, and quenching of tentacles, are the biomarkers of the snails for biomonitoring. Different snails can bio-monitor eco-toxicological urban pollution, oil pollutant, terrestrial pollution, pesticide pollutants, mercury contamination, ammonia, chlorinated paraffin in soil, ethanol in water, ocean acidification pollutions. These animals can also make bio-sense about diverse environment spheres, which include the biosphere, lithosphere, anthroposphere, cryosphere, and hydrosphere.Methods: We examined the scientific literature and related articles listed in Pub-med, Google Scholar reporting on biomonitoring potential and biomarkers expression of various snail species and consequently explore the value of snails in the respective field by discussing various outcomes of a number of studies on the pollution biomonitoring and biosensing capabilities.Results: Several terrestrial, freshwater and sea snail species are characterized by the high sense of biomonitoring and biosensing potential. Various biomarkers such as expression of heat shock proteins and metallothioneins in the body are found to be the essential in-vivo biomarkers for pollution biomonitoring.Conclusion: It is observed that snails offer an environment friendly approach for the environmental bio monitoring by expressing their numerous physiological, biochemical, genetical and histological biomarkers in their body. Thus, it proved to be a critical bio monitoring tool and early warning indicators.

Exposure to Dichlorodiphenyldichloroethylene (DDE) and Metallothionein Levels in Rats Fed with Normocaloric or High-Fat Diet: A Review

The growing number of studies on metallothioneins (MTs), cysteine-rich metal-binding proteins, have been disclosing new functions of these proteins. Thanks to their inducibility, they were considered to play a pivotal role in regulating trace metals homeostasis and in detoxification from heavy metals; nowadays, it is known that they are involved in various physiological and pathological processes, such as regulation of apoptosis, elimination of free radicals, and protection of nucleic acids against toxic insults. MT induction has been demonstrated following stress factors other than heavy metals, such as endocrine-disrupting chemicals, insecticides, and herbicides. However, retrieved data are often controversial: in some cases, xenobiotics elicit MT expression and synthesis; under different conditions, they lead to a decrease in cellular MT content. This review describes the MT response to dichlorodiphenyltrichloroethane (DDT) contamination in mammalian tissues. In particular, attention focuses on changes in MT expression, synthesis, and localization in rat liver, kidneys, and testes following oral administration of dichlorodiphenyldichloroethylene (DDE), the main metabolite of DDT, under normal dietary conditions or in combination with a high fat diet potentially able to increase the cellular uptake of this lipophilic pesticide. The potential connection between MT expression and synthesis, lipophilic substances and trace metals availability is also discussed.