Frog (Pelophylax bergeri, Günther 1986) endocrine disruption assessment: characterization and role of skin poly(ADP-ribose) polymerases

Exploring the molecular and toxicological mechanism associated with interactions between heavy metals and the reproductive system of Mytilus galloprovincialis

A large number of heavy metals resulted toxic to the reproductive system, but invertebrate infertility has been poorly explored, and above all, there are limited molecular, cellular and toxicological studies. In the present work, we exposed Mytilus galloprovincialis to three individual metal chlorides (CuCl2 15 μM, CdCl2 1.5 μM, NiCl2 15 μM) and their mixture for 24 h, to evaluate the effects on the protamine-like proteins (PLs), sperm DNA and on their interaction in the formation of sperm chromatin. Under all exposure conditions, but particularly after exposure to the metals mix, relevant changes in the electrophoretic pattern, by AU-PAGE and SDS-PAGE, and in fluorescence spectroscopy measurements of PLs were shown. In addition, alterations in DNA binding of these proteins were observed by Electrophoretic Mobility Shift Assay (EMSA) and through their release from sperm nuclei. Moreover, there was evidence of increased accessibility of micrococcal nuclease to sperm chromatin, which was also confirmed by toluidine blue staining. Furthermore, morphological analyses indicated severe gonadal impairments which was also corroborated by increased PARP expression, by Western blotting, and sperm DNA fragmentation, by comet assay. Finally, we investigated the expression of stress genes, gst, hsp70 and mt10, in gonadal tissue. The latter investigations also showed that exposure to this metals mix was more harmful than exposure to the individual metals tested. The present results suggest that these metals and in particular their mixture could have a negative impact on the reproductive fitness of M. galloprovincialis. Based on these evidences, we propose a molecular mechanism.

Synthesis and Degradation of Poly(ADP-ribose) in Zebrafish Brain Exposed to Aluminum

Poly(ADPribosyl)ation is a post-translational protein modification, catalyzed by poly(ADP-ribose) polymerase (PARPs) enzymes, responsible for ADP-ribose polymer synthesis (PAR) from NAD⁺. PAR turnover is assured by poly(ADPR) glycohydrolase (PARGs) enzymes. In our previous study, the altered histology of zebrafish brain tissue, resulting in demyelination and neurodegeneration also with poly(ADPribosyl)ation hyperactivation, was demonstrated after aluminum (Al) exposure for 10 and 15 days. On the basis of this evidence, the aim of the present research was to study the synthesis and degradation of poly(ADP-ribose) in the brain of adult zebrafish exposed to 11 mg/L of Al for 10, 15, and 20 days. For this reason, PARP and PARG expression analyses were carried out, and ADPR polymers were synthesized and digested. The data showed the presence of different PARP isoforms, among which a human PARP1 counterpart was also expressed. Moreover, the highest PARP and PARG activity levels, responsible for the PAR production and its degradation, respectively, were measured after 10 and 15 days of exposure. We suppose that PARP activation is related to DNA damage induced by Al, while PARG activation is needed to avoid PAR accumulation, which is known to inhibit PARP and promote parthanatos. On the contrary, PARP activity decrease at longer exposure times suggests that neuronal cells could adopt the stratagem of reducing polymer synthesis to avoid energy expenditure and allow cell survival.

A Molecular Mechanism to Explain the Nickel-Induced Changes in Protamine-like Proteins and Their DNA Binding Affecting Sperm Chromatin in Mytilus galloprovincialis: An In Vitro Study

Nickel is associated with reproductive toxicity, but little is known about the molecular mechanisms of nickel-induced effects on sperm chromatin and protamine-like proteins (PLs). In the present work, we analyzed PLs from Mytilus galloprovincialis by urea-acetic acid polyacrylamide gel electrophoresis (AU-PAGE) and SDS-PAGE and assessed their binding to DNA by Electrophoretic Mobility Shift Assay (EMSA) after exposing mussels to 5, 15, and 35 µM NiCl2 for 24 h. In addition, a time course of digestion with MNase and release of PLs from sperm nuclei by the NaCl gradient was performed. For all exposure doses, in AU-PAGE, there was an additional migrating band between PL-III and PL-IV, corresponding to a fraction of PLs in the form of peptides detected by SDS-PAGE. Alterations in DNA binding of PLs were observed by EMSA after exposure to 5 and 15 µM NiCl2, while, at all NiCl2 doses, increased accessibility of MNase to sperm chromatin was found. The latter was particularly relevant at 15 µM NiCl2, a dose at which increased release of PLII and PLIII from sperm nuclei and the highest value of nickel accumulated in the gonads were also found. Finally, at all exposure doses, there was also an increase in PARP expression, but especially at 5 µM NiCl2. A possible molecular mechanism for the toxic reproductive effects of nickel in Mytilus galloprovincialis is discussed.

Anthropic impact on soil heavy metal contamination in riparian ecosystems of northern Algeria

The aim of this research was to highlight the impact of urbanization and agriculture on soil quality, mainly by focusing on heavy metal accumulation (Cd, Cu, Fe, Mn, Ni, Pb and Zn) in the fragile riparian ecosystems of the Medjerda river (Souk-Ahras, Algeria). This study was performed in three cultivated soils (0-10, 10-20, 20-60 cm depth) along an increasing gradient of anthropogenic pressure in non-urban (NU), peri-urban (PU) and urban areas (U). Geo-accumulation index (Igeo), Enrichment factor (EF), Pollution load index (PLI) and Potential ecological risk index (RI) were calculated, as well as the potential non-carcinogenic risk for humans (HI). Additionally, to corroborate the role of Bufo spinosus D. as biosentinel, a skin biopsy was performed to quantify the concentration of heavy metals in both terrestrial and aquatic ecosystems. The results showed that when compared to NU, U and PU areas were richer in heavy metals. In particular, Igeo-Cd displayed strongly contaminated soil in U (>3), EF showed high enrichment of heavy metals (>2) for all the soils except for Ni, PLI presented no contamination for all (<1) while RI was significantly higher in U (>300), denoting a strong impact of heavy metals on soil quality. However, HI was below 1 for all the studied areas, although the highest values were related to U and PU. The skin biopsy showed the highest values for Cu, Fe and Pb in PU (0.328, 0.713 and 0.524 mg kg^-1, respectively) similarly to trends observed in the soil of that area. This study shed light on the rising pollution of heavy metals due to urbanization and agricultural input in these fragile ecosystems where Bufo spinosus D. plays the role of potential bio-indicator for environmental pollution.

Aluminium exposure leads to neurodegeneration and alters the expression of marker genes involved to parkinsonism in zebrafish brain

Aluminium, despite being extremely widespread in the world, is a non-essential metal to human metabolism. This metal is known to have toxic effects on a variety of organs including the brain and is considered an etiological factor in neurodegenerative diseases. However, the molecular mechanisms by which aluminium exerts neurotoxic effects are not yet completely understood. Zebrafish is an animal model also used to study neurodegenerative diseases since the overall anatomical organization of the central nervous system is relatively conserved and similar to mammals. Adult zebrafish were exposed to 11 mg/L of Al for 10, 15, and 20 days and the neurotoxic effects of aluminium were analysed by histological, biochemical, and molecular evaluations. Histological stainings allowed to evaluation of the morphology of the brain parenchyma, the alteration of myelin and the activation of neurodegenerative processes. The expression of the Glial Fibrillary Acidic Protein, a marker of glial cells, was evaluated to observe the quantitative alteration of this important protein for the nervous system. In addition, the poly(ADP-ribose) polymerase activity was measured to verify a possible oxidative DNA damage caused by exposure to this metal. Finally, the evaluation of the markers involved in Parkinsonism was assessed by Real-Time PCR to better understand the role of aluminium in the regulation of genes related to Parkinson's neurodegenerative disease. Data showed that aluminium significantly affected the histology of cerebral tissue especially in the first periods of exposure, 10 and 15 days. This trend was also followed by the expression of GFAP. At longer exposure times, there was an improvement/stabilization of the overall neurological conditions and decrease in PARP activity. In addition, aluminium is involved in the deregulation of the expression of genes closely related to Parkinsonism. Overall, the data confirm the neurotoxicity induced by aluminium and shed a light on its involvement in neurodegenerative processes.

Biological Effects Assessment of Antibiofouling EDCs: Gaeta Harbor (South Italy) Benthic Communities' Analysis by Biodiversity Indices and Quantitative gpx4 Expression

The most representative organisms of the Harbor of Gaeta Gulf in South Italy were analyzed for biofouling by visual census and confirmed later by molecular approach on an artificial Conatex panel dipped 3 m into a eutrophic area during the Covid-19 pandemic. Mitochondrial Cytochrome C oxidase subunit 1(COI) gene was sequenced from 20 different marine species (flora: 2 families, 2 orders; fauna: 16 families, 11 orders) to test whether the morphology-based assignment of the most common biofouling member was supported by DNA-based species identification. Twelve months of submersion resulted in generation of sufficient data to obtain a facies climax represented mainly by the bivalve mollusk, Mytilus galloprovincialis. Specific diversity and variations of the biofouling biomasses were analyzed using two different anti-biofouling paints: an endocrine disrupting chemical (EDC)-containing metal biocide, and a biocide-free paint. Also, their effects on detoxification and reproductive health of M. galloprovincialis were evaluated using glutathione S-transferase enzymatic activity and RTqPCR expression of the fertility antioxidant gene glutathione peroxidase 4 (gpx4). The obtained data provide useful indications on which future investigations may be focused and may become a potential management tool for a harbor biofouling database to assist local administrations in EDCs protection of autochthonous benthic communities and their fertility using innovative antifouling paints.

PARPs in lipid metabolism and related diseases

PARPs and tankyrases (TNKS) represent a family of 17 proteins. PARPs and tankyrases were originally identified as DNA repair factors, nevertheless, recent advances have shed light on their role in lipid metabolism. To date, PARP1, PARP2, PARP3, tankyrases, PARP9, PARP10, PARP14 were reported to have multi-pronged connections to lipid metabolism. The activity of PARP enzymes is fine-tuned by a set of cholesterol-based compounds as oxidized cholesterol derivatives, steroid hormones or bile acids. In turn, PARPs modulate several key processes of lipid homeostasis (lipotoxicity, fatty acid and steroid biosynthesis, lipoprotein homeostasis, fatty acid oxidation, etc.). PARPs are also cofactors of lipid-responsive nuclear receptors and transcription factors through which PARPs regulate lipid metabolism and lipid homeostasis. PARP activation often represents a disruptive signal to (lipid) metabolism, and PARP-dependent changes to lipid metabolism have pathophysiological role in the development of hyperlipidemia, obesity, alcoholic and non-alcoholic fatty liver disease, type II diabetes and its complications, atherosclerosis, cardiovascular aging and skin pathologies, just to name a few. In this synopsis we will review the evidence supporting the beneficial effects of pharmacological PARP inhibitors in these diseases/pathologies and propose repurposing PARP inhibitors already available for the treatment of various malignancies.

Bioaccumulation of Metals/Metalloids and Histological and Immunohistochemical Changes in the Tissue of the European Hake, Merluccius merluccius (Linnaeus, 1758) (Pisces: Gadiformes: Merlucciidae), for Environmental Pollution Assessment

Pollution and other types of environmental stress do not spare marine environments, especially those affected by high industrial pressure. Fish, especially coastal species, are used for monitoring the marine environment because they are particularly efficient as bioindicators thanks to their ability to bioaccumulate and biomagnify along the trophic chain. The aim of this research is to evaluate the bioaccumulation and the indirect bioindication ability of the European Hake, Merluccius merluccius (Linnaeus, 1758), one of the most important commercial fish species of the Mediterranean Sea. Morphological and histological alterations of the main target organs, such as liver and gills, have been investigated and the results showed a steatosis in the hepatic tissue. The accumulation of heavy metals has been analyzed by inductively coupled plasma mass spectrometry and for several metals it was showed a different concentration in the two sexes. Moreover, the expression of metallothioneins 1 and Heat Shock Protein 70 has been assessed by immunohistochemistry and did not show high level of expression. We underline the importance of contamination evaluation in commercial fish species and the utilization of the ichthyofauna as bioindicator of environmental quality.

Morphological analysis reveals the presence of Hepatoxylon trichiuri (Holten, 1802) Bosc, 1811 (Cestoda: Sphyriocephalidae) in Lepidopus caudatus (Euphrasen, 1788) (Pisces: Trichiuridae) from the Mediterranean Sea

In this article, we report for the first time the presence of the parasite Hepatoxylon trichiuri in specimens of Lepidopus caudatus from the Mediterranean Sea. A total of four plerocercoids were studied using microscopy techniques for both morphological and histological analysis. RESEARCH HIGHLIGHTS: We report for the first time for the Mediterranean Sea the presence of the parasite Hepatoxylon trichiuri in specimens of the commercial fish species Lepidopus caudatus. The plerocercoids of H. trichiuri not seems cause observable illness in the fish. However, further studies are needed in order to better assess the incidence and prevalence of the parasite in L. caudatus and other fish species of commercial interest.

Biochemical parameters in skin and muscle of Pelophylax kl. esculentus frogs: Influence of a cyanobacterial bloom in situ

There is little information in scientific literature as to how conditions created by a microcystin (MC) producing cyanobacterial bloom affect the oxidant/antioxidant, biotransformation and neurotoxicity parameters in adult frogs in situ. We investigated biochemical parameters in the skin and muscle of Pelophylax kl. esculentus from Lake Ludaš (Serbia) by comparing frogs that live on the northern bloom side (BS) of the lake with those that inhabit the southern no-bloom side (NBS). A higher protein carbonylation level and lower antioxidant defense system capability in the skin of frogs living in conditions of the cyanobacterial bloom were observed. Inhibition of glutathione-dependent machinery was the major mechanism responsible for the induction of cyanobacterial bloom-mediated oxidative stress in frog skin. On the other hand, the detected higher ability of muscle to overcome bloom prooxidant toxicity was linked to a higher efficiency of the biotransformation system through glutathione-S-transferase activity and/or was the consequence of indirect exposure of the tissue to the bloom. Our results have also revealed that the cyanobacterial bloom conditions induced the cholinergic neurotransmitter system in both tissues. This study provides a better understanding of the ecotoxicological impact of the MC producing cyanobacterial bloom on frogs in situ. However, further investigations of the complex mechanism involved in cyanobacterial bloom toxicity in real environmental conditions are required.

The role of ADP-ribose metabolism in metabolic regulation, adipose tissue differentiation, and metabolism

In this review, Szanto et al. summarize the metabolic regulatory roles of PARP enzymes and their associated pathologies.

Poly(ADP-ribose) polymerases (PARPs or ARTDs), originally described as DNA repair factors, have metabolic regulatory roles. PARP1, PARP2, PARP7, PARP10, and PARP14 regulate central and peripheral carbohydrate and lipid metabolism and often channel pathological disruptive metabolic signals. PARP1 and PARP2 are crucial for adipocyte differentiation, including the commitment toward white, brown, or beige adipose tissue lineages, as well as the regulation of lipid accumulation. Through regulating adipocyte function and organismal energy balance, PARPs play a role in obesity and the consequences of obesity. These findings can be translated into humans, as evidenced by studies on identical twins and SNPs affecting PARP activity.

Antioxidative Defense and Fertility Rate in the Assessment of Reprotoxicity Risk Posed by Global Warming

The objective of this review is to briefly summarize the recent progress in studies done on the assessment of reprotoxicity risk posed by global warming for the foundation of strategic tool in ecosystem-based adaptation. The selected animal data analysis that was used in this paper focuses on antioxidative markers and fertility rate estimated over the period 2000-2019. We followed a phylogenetic methodology in order to report data on a panel of selected organisms that show dangerous effects. The oxidative damage studies related to temperature fluctuation occurring in biosentinels of different invertebrate and vertebrate classes show a consistently maintained physiological defense. Furthermore, the results from homeothermic and poikilothermic species in our study highlight the influence of temperature rise on reprotoxicity.

Toxicity assessment of nano-TiO2 in Apis mellifera L., 1758: histological and immunohistochemical assays

The aim of this study was to evaluate the toxicity of titanium dioxide nanoparticles (TiO₂ NPs) by short-term toxicity tests in Apis mellifera, considered an excellent bioindicator organism mainly due to its sensitivity. Bees have been exposed to several concentrations of TiO₂ NPs (1 × 10^-3 , 1 × 10^-4 , 1 × 10^-5 , 1 × 10^-6 mg/10 ml) for 10 days. Morphostructural and histological assays were done on gut and honey sac. The research of exposure biomarkers like metallothioneins 1 (MT1) and Heat Shock Protein 70 (HSP70) was performed to verify if a detoxification mechanism has been activated in the exposed animals. No histological alteration on the epithelium of the gut and honey sac were observed in exposed samples. A significant positivity for anti-MT1 antibody was observed only in the honey sac cells. A weak positivity for HSP70 was observed in both structures analyzed. In several studies have shown the non-toxicity of TiO₂ NPs on other model organisms, in our study, titanium dioxide nanoparticles was proven to be highly toxic at the highest concentration tested (100% of lethality to 1 × 10^-3 mg/10 ml) and moderately toxic at lower concentrations. Honey bees proved to be excellent models for study of NPs toxicity and for monitoring environment.

Toxicity Evaluation of Graphene Oxide and Titania Loaded Nafion Membranes in Zebrafish

The use of nanomaterials in several application fields has received in the last decades a great attention due to their peculiar properties, but also raised many doubts about possible toxicity when these materials are used for some specific applications, such as water purification. Indeed a careful investigation is needed in order to exclude possible harmful side effects related to the use of nanotechnology. Nanoparticles effects on the marine organisms may depend on their chemical composition, size, surface structure, solubility, shape and how the individual nanoparticles aggregate together. In order to make the most of their potential, without polluting the environment, many researchers are trying to trap them into some kind of matrix that keeps them active but avoids their dispersion in the environment. In this study we have tested nanocomposite membranes prepared using Nafion polymer combined with various fillers, such as anatase-type TiO2 nanoparticles and graphene oxide. The non-toxicity of these nanocomposites, already shown to be effective for water purification applications in our previous studies, was recognized by testing the effect of the different materials on zebrafish embryos. Zebrafish was considered an excellent model for ecotoxicological studies and for this motivation zebrafish embryos were exposed to different concentrations of free nanoparticles and to the nanocomposite membranes. As biomarkers of exposure, we evaluated the expression of heme-oxygenase 1 and inducible Nitric Oxide Synthases by immunohistochemistry and gene expression. Embryo toxicity test showed that nor sublethal effects neither mortality were caused by the different nanoparticles and nano-systems tested. Only zebrafish larvae exposed to free nanoparticles have shown a different response to antibodies anti-heme-oxygenase 1 and anti- inducible Nitric Oxide Synthases. The immunolocalization analysis in fact has highlighted an increase in the synthesis of these biomarkers.