Contextualization of causal regulatory networks from toxicogenomics data applied to drug-induced liver injury.

In recent years, network-based methods have become an attractive analytical approach for toxicogenomics studies. They can capture not only the global changes of regulatory gene networks but also the relationships between their components. Among them, a causal reasoning approach depicts the mechanisms of regulation that connect upstream regulators in signaling networks to their downstream gene targets. In this work, we applied CARNIVAL, a causal network contextualisation tool, to infer upstream signaling networks deregulated in drug-induced liver injury (DILI) from gene expression microarray data from the TG-GATEs database. We focussed on six compounds that induce observable histopathologies linked to DILI from repeated dosing experiments in rats. We compared responses in vitro and in vivo to identify potential cross-platform concordances in rats as well as network preservations between rat and human. Our results showed similarities of enriched pathways and network motifs between compounds. These pathways and motifs induced the same pathology in rats but not in humans. In particular, the causal interactions "LCK activates SOCS3, which in turn inhibits TFDP1" was commonly identified as a regulatory path among the fibrosis-inducing compounds. This potential pathology-inducing regulation illustrates the value of our approach to generate hypotheses that can be further validated experimentally.

Proteomics analysis of zebrafish larvae exposed to 3,4-dichloroaniline using the fish embryo acute toxicity test.

The zebrafish (Danio rerio) is a small teleost fish that is becoming increasingly popular in laboratories worldwide and several attributes have also placed the zebrafish under the spotlight of (eco)toxicological studies. Since the 1990s, international organizations such as ISO and OECD have published guidelines for the use of zebrafish in ecotoxicological assessment of environmental toxicants such as the Fish Embryo Acute Toxicity (FET) test, OECD n° 236 guideline. This protocol uses 3,4-dichloroaniline (DCA), an aniline pesticide whose toxicity to fish species at early life stages is well known, as a positive control. Despite its use, little is known about its molecular mechanisms, especially in the context of the FET test. Therefore, this study aimed to investigate such changes in zebrafish larvae exposed to DCA (4 mg/L) for 96 hours using gel-free proteomics. Twenty-four proteins detected in both groups were identified as significantly affected by DCA exposure, and, when considering group-specific entities, 48 proteins were exclusive to DCA (group-specific proteins) while 248 were only detected in the control group. Proteins modulated by DCA treatment were found to be involved in metabolic processes, especially lipids and hormone metabolism (eg, Apoa1 and Apoa1b and vitelogenins), as well as proteins important for developmental processes and organogenesis (eg, Myhc4, Acta2, Sncb, and Marcksb). The results presented here may therefore provide a better understanding of the relationships between molecular changes and phenotype in zebrafish larvae treated with DCA, the reference compound of the FET test.

In vitro toxicological characterisation of the antifungal compound soybean toxin (SBTX).

Soybean toxin (SBTX) is a protein isolated from soybean seeds and composed of two polypeptide subunits (17 and 27 kDa). SBTX has in vitro activity against phytopathogenic fungi such as Cercospora sojina, Aspergillus niger, and Penicillium herguei, and yeasts like Candida albicans, C. parapsilosis, Kluyveromyces marxiannus, and Pichia membranifaciens. The present study aimed to analyze in vitro whether SBTX causes any side effects on non-target bacterial and mammalian cells that could impede its potential use as a novel antifungal agent. SBTX at 100 µg/mL and 200 µg/mL did not hinder the growth of the bacteria Salmonella enterica (subspecies enterica serovar choleraesuis), Bacillus subtilis (subspecies spizizenii) and Staphylococcus aureus. Moreover, SBTX at concentrations up to 500 µg/mL did not significantly affect the viability of erythrocytes, neutrophils, and human intestinal Caco-2 cells. To study whether SBTX could induce relevant alterations in gene expression, in vitro DNA microarray experiments were conducted in which differentiated Caco-2 cells were exposed for 24 h to 100 µg/mL or 200 µg/mL SBTX. SBTX up-regulated genes involved in cell cycle and immune response pathways, but down-regulated genes that play a role in cholesterol biosynthesis and platelet degranulation pathways. Thus, although SBTX did not affect bacteria, nor induced cytotoxity in mammalian cells, it affected some biological pathways in the human Caco-2 cell line that warrants further investigation.

Toxicity testing of pesticides in zebrafish-a systematic review on chemicals and associated toxicological endpoints.

The use of zebrafish (Danio rerio) has arisen as a promising biological platform for toxicity testing of pesticides such as herbicides, insecticides, and fungicides. Therefore, it is relevant to assess the use of zebrafish in models of exposure to investigate the diversity of pesticide-associated toxicity endpoints which have been reported. Thus, this review aimed to assess the recent literature on the use of zebrafish in pesticide toxicity studies to capture data on the types of pesticide used, classes of pesticides, and zebrafish life stages associated with toxicity endpoints and phenotypic observations. A total of 352 articles published between September 2012 and May 2019 were curated. The results show an increased trend in the use of zebrafish for testing the toxicity of pesticides, with a great diversity of pesticides (203) and chemical classes (58) with different applications (41) being used. Furthermore, experimental outcomes could be clustered in 13 toxicity endpoints, mainly developmental toxicity, oxidative stress, and neurotoxicity. Organophosphorus, pyrethroid, azole, and triazine were the most studied classes of pesticides and associated with various toxicity endpoints. Studies frequently opted for early life stages (embryos and larvae). Although there is an evident lack of standardization of nomenclatures and phenotypic alterations, the information gathered here highlights associations between (classes of) pesticides and endpoints, which can be used to relate mechanisms of action specific to certain classes of chemicals.

Risk assessment of the antifungal and insecticidal peptide Jaburetox and its parental protein the Jack bean (Canavalia ensiformis) urease.

Jaburetox (JBTX) is an insecticidal and antifungal peptide derived from jack bean (Canavalia ensiformis) urease that has been considered a candidate for developing genetically modified crops. This study aimed to perform the risk assessment of the peptide JBTX following the general recommendations of the two-tiered, weight-of-evidence approach proposed by International Life Sciences Institute. The urease of C. ensiformis (JBU) and its isoform JBURE IIb (the JBTX parental protein) were assessed. The history of safe use revealed no hazard reports for the studied proteins. The available information shows that JBTX possesses selective activity against insects and fungi. JBTX and JBU primary amino acids sequences showed no relevant similarity to toxic, antinutritional or allergenic proteins. Additionally, JBTX and JBU were susceptible to in vitro digestibility, and JBU was also susceptible to heat treatment. The results did not identify potential risks of adverse effects and reactions associated to JBTX. However, further allergen (e.g. serum IgE binding test) and toxicity (e.g. rodent toxicity tests) experimentation can be done to gather additional safety information on JBTX, and to meet regulatory inquiries for commercial approval of transgenic cultivars expressing this peptide.

Further insecticidal activities of essential oils from Lippia sidoides and Croton species against Aedes aegypti L.

This study assessed new insecticidal activities of essential oils from Lippia sidoides and Croton species (Croton zehntneri, Croton nepetaefolius, Croton argyrophylloides, and Croton sonderianus) against Aedes aegypti mosquito. In addition, the acute toxicity upon mice was determined. All essential oils showed inhibition of egg hatching, with IC50 values ranging from 66.4 to 143.2 µg mL(-1), larvicidal activity with LC50 ranging from 25.5 to 94.6 µg mL(-1), and pupicidal action with PC50 ranging from 276.8 to over 500 µg mL(-1). Only L. sidoides, C. zehntneri, and C. argyrophylloides essential oils were able to inhibit the oviposition of female gravid mosquitoes with OD50 values of 35.3, 45.3, and 45.8 µg mL(-1), respectively. Oral acute toxicity in mice showed that C. sonderianus and C. argyrophylloides oils are nontoxic (LD50 > 6,000 mg.kg(-1)) while C. nepetaefolius, C. zehntneri, and L. sidoides oils are moderately toxic (LD50 3,840; 3,464, and 2,624 mg.kg(-1), respectively). The results indicate that these oils are promising sources of bioactive compounds, showing low or no toxicity to mammals.

Antibacterial, antioxidant, and anticholinesterase activities of plant seed extracts from Brazilian semiarid region.

The antimicrobial, antioxidant, and anticholinesterase activities of ethanolic seed extracts of twenty-one plant species from Brazilian semiarid region were investigated. The extracts were tested for antimicrobial activity against six bacteria strains and three yeasts. Six extracts presented activity against the Gram (-) organism Salmonella choleraesuis and the Gram (+) organisms Staphylococcus aureus and Bacillus subtilis. The MIC values ranged from 4.96 to 37.32 mg/mL. The Triplaris gardneriana extract presented activity against the three species, with MIC values 18.8, 13.76, and 11.15 mg/mL, respectively. Five extracts presented antioxidant activity, with EC50 values ranging from 69.73 µ g/mL (T. gardneriana) to 487.51 µ g/mL (Licania rigida). For the anticholinesterase activity, eleven extracts were capable of inhibiting the enzyme activity. From those, T. gardneriana, Parkia platycephala and Connarus detersus presented the best activities, with inhibition values of 76.7, 71.5, and 91.9%, respectively. The extracts that presented antimicrobial activity were tested for hemolytic assay against human A, B, and O blood types and rabbit blood. From those, only the Myracrodruon urundeuva extract presented activity (about 20% of hemolysis at the lowest tested concentration, 1.9 µg/mL). Infrared spectroscopy of six representative extracts attested the presence of tannins, polyphenols, and flavonoids, which was confirmed by a qualitative phytochemical assay.

Contaminaçäo por mercúrio nos garimpos paraenses / Contamination to mercury in the \"garimpos paraenses\"

Mercury is one of the most noxious metal in nature and it has been responsible for two of the world's greatest ecological hazards. The metal is intensively used in gold garimpos since 1980 so that the discharge of mercury in the environment is of great concern among the competent authorities both mineral and environmental. Actually Brazil depends 100 per cent on imported mercury and from 1977 to 1987 roughly 1.800 tons of metal were imported at the value of S$16,3 milhöes CIF. In order to preserve the environment, the Departamento Nacional da Produçäo Mineral (DNPM), jointly with other institutions concerned with the pollution affairs, is engaged in works for controlling the mercury discharges in the most important garimpos areas. The results of blood, urine, fish and birds tissue, sediments, water and some vegetables campling at designated points in the Tapajós region, as well as natives and garimpeiros hair sampling in Cumaru area; swine tissue and garimpeiros hair analysis in Gurupi region besides sampling and chemical analysis of soil and sediments from Serra Pelada garimpo site, are not following the allowable limits concerning human health and living environment. The sampling and chemical analysis results are far from covering over-all problems - on mercury pollution in the garimpo regions because of the small quantity of analysis for evaluation of environmental survey of the garimpo sites, although the high level of contamination by mercury and its compounds is worrying the government officials and local communities. Some suggestions have been presented in prevention of mercury pollution, among them it can be pointed out the equipments to prevent mercury discharge in the garimpo sites which has been developed by DNPM