Teaching - Università degli Studi della Tuscia

Tossicologia genetica (objectives)

LEARNING OBJECTIVES
Genetic toxicology has developed as a discipline independent of Genetics with the aim of defining a robust programme to control the spread of chemical, physical and biological mutagenic agents in the environment. The discovery of an increasing number of mutagenic substances already present or continuously introduced in the environment and the confirmation of the increasingly close correlation between mutagenic processes, carcinogenesis and hereditary genetic diseases, has led to the development of laboratory methods capable of identifying mutagenic substances and the development of monitoring systems to assess the onset of genetic effects in the human population. The aim of the class is to acquire basic knowledge related to the metabolism of xenobiotics, the action of ionizing radiation and biological mutagens and the interaction between mutagenic agents and hereditary material. At a later stage, the theoretical and practical aspects of the main short-term mutagenicity tests will be presented.
EXPECTED LEARNING OUTCOMES
1) Knowledge and understanding:
• Knowledge of the fundamental dynamics of the generation of genetic mutations through the different mechanisms of formation of "primary lesions" to DNA, consequent DNA repair processes and final fixation of the mutations;
• Knowledge of the phenotypic effects of mutations at the somatic level (individual), in relation to the development of neoplasms and/or degenerative conditions such as premature ageing, immune, cardiovascular and neurodegenerative dysfunctions and mutations at germinal level (transgenerational effects) related to hereditary genetic diseases;
•Knowledge of the interindividual (human) effects induced by mutagens in relation to the different metabolic capacities regulated by polymorphic metabolic genes (P-450);
•Acquisition of the ability to use "in silico" methodologies (QSAR models) that allow to establish the relationships between the chemical structure of a substance and the specific properties or activities of the compound itself (e.g. sensitization, genotoxicity, carcinogenicity).

2. Applying knowledge and understanding:
•Identification of appropriate "mutagenesis test batteries" selection strategies for an efficient and correct definition of the genotoxic potential of a specific agent (natural active substances, synthetic and biotechnological drugs, food additives, agrochemicals, biocides, etc.) at the three fundamental levels of genetic material organization (gene, chromosomal and genomic) and a possible "risk assessment" for humans.

3. Making judgements:
•The teaching will provide the student with the ability to work autonomously by providing appropriate types of teaching materials (lectures in the form of presentations, specific monographs, relevant scientific literature, computer platforms) and the performance of appropriate laboratory activities synchronized with the theoretical part of the course.

4. Communication skills:
•Students will be appropriately stimulated to actively participate in the activities of course and to design and solve specific scenarios related to the different evolutionary phases of the class. In this regard, in the final phase of the laboratory activities, students will identify autonomously a "model" of a mutagenic agent and its assay strategy.

5. Learning skills:
The students' learning skills will be evaluated in progress and verified through the ability to solve relevant and specific scenarios of interest, different from those proposed during the class.

Code

18431

Language

ITA

Type of certificate

Profit certificate

Credits

Scientific Disciplinary Sector Code

BIO/18

Contact Hours

Laboratory Hours

Type of Activity

Core compulsory activities

Teacher	MOSESSO Pasquale (syllabus) 1) Introduction to Genetic Toxicology Origin and history of Genetic Toxicology. Chemical structure and morphological organisation of genetic material. Definition and classification of mutations: Gene mutations: base pair substitutions, insertions, deletions; reversion and suppression of mutations; phenotypic effects of gene mutations. Fluctuation test and spontaneous mutation in bacteria (neo Darwinian theory). Chromosome mutations: structural (chromosomal aberrations) and numerical (aneuploidy, polyploidy). 2) Spontaneous DNA alterations Mis-incorporation of bases that can arise during DNA replication (mismatch, tautomerization of bases) and “proof-reading” mechanism for correction of errors. Deamination of bases, spontaneous loss of bases and oxidative damage to DNA. Molecular mechanisms of insertion and deletions of bases. 3) Environmental agents which damage DNA Physical mutagens: Ionizing electromagnetic radiations (X-rays, γ-rays, betatron-synchrotron radiations; Ionizing subatomic particles (alpha particles, beta particles neutrons). Non-ionizing electromagnetic radiations (UV-A, UV-B, UV-C); UV and ozone. Electromagnetic fields (microwaves, HF, ELF etc.). Direct and indirect action of ionizing radiations on DNA and “S-independent” mechanism of induction of chromosomal aberrations. Chemical mutagens: Direct and indirect chemical mutagens (metabolic activation); alkylating agents; environmental pollutants in the cities [car exhaust, sulphur and nitrogen oxides, polycyclic aromatic hydrocarbons (PAH), formaldehyde, asbestos]; Food additives and contaminant of aliments (aflatoxins, ochratoxins nitrosamines, heterocyclic aromatic amines, phenols of vegetal origin, etc); therapeutic agents (mitomycin-C, bleomycin, nitrogen mustards, inhibitors of DNA topoisomerases I and II, cytostatic agents); pesticides. “S-dependent” mechanism of chemical mutagens. Biological mutagens: microbial and viral pathogens; transposable elements. 4) Systems of defence and cell response to DNA damage Antioxidant and non-antioxidant systems of defence (superoxide dismutase, catalase, peroxidase, α- tocopherol, vitamin-C, carotenoids, flavonoids, polyphenols etc). Detoxification systems of xenobiotics: (phase I and phase II enzymes); DNA repair systems: fotoliase, alchiltransferases, “nucleotide excision repair” (NER), “base excision repair (BER), “mismatch repair” (MMR), “SOS” repair, recombinational repair: repair of DNA single strand breaks (SSB) and DNA double strand breaks (HR e NHEJR); DNA damage, activation of cellular “checkpoints, restoration of wild type condition, induction of mutation, apoptosis and genomic instability. 5) Phenotypic effects of somatic and germinal mutations Mutation and cancer (activation of proto-oncogenes and deactivation of tumor suppressor genes); Mutation and cellular aging; Mutations and genetic diseases (Down, Klinefelter, Edwards, Xeroderma pigmentosum, Ataxia telangiectasia, Bloom syndromes). 6) Assays for detection of genotoxicity In vitro short-term mutagenicity tests: Gene mutation assay in bacteria (Salmonella typhimurium reversion assay in or Ames test); Gene mutation assay in mammalian cells (loci HPRT or TK+/-); Cytogenetic tests in mammalian cells (chromosomal aberrations, sister chromatid exchanges, micronuclei). In vivo short-term mutagenicity assays: Test of chromosome mutation in somatic cells (analyses of cells in metaphase); micronucleus test in bone marrow erythrocytes of rodents; Comet assay; Unscheduled DNA synthesis (UDS). 7) Biomonitoring of human populations Biomarkers of exposure (mutagenic activity of mutagens or their metabolites in the urines; determination of chemical adducts to proteins or DNA); Biomarkers of effects: cytogenetics changes (chromosome aberrations, micronuclei, aneuploidy) in peripheral blood lymphocytes or cells of buccal mucosa; Biomarkers of susceptibility: differential DNA repair capability among different individuals; polymorfism of metabolic enzymes. 8) Evaluation and regulation of mutagenic risk Testing strategies and prediction of somatic effects (cancer, genetic diseases) following exposure to genotoxic agents; Food safety and strategies for risk assessment; identification of threshold values of exposure; regulatory aspects. 9) Practise exercise (obligatory): Evaluation of mutagenic compounds (selected by students) in the following mutagenicity assays: • Cytogenetic analyses of chromosome aberrations, sister chromatid exchanges (SCE’s) and micronuclei in mammalian cells in vitro; • Analyses of DNA breakage in human lymphocytes by the alkaline “Comet assay”. (reference books) L. Migliore “Genomica e Mutagenesi Ambientale” Testi aggiuntivi (disponibili in biblioteca): A.P. LI “Genetic Toxicology” D.H. Phillips and S. Venitt “Environmental Mutagenesis” R.H. Burdon “Genes and Environment”
Dates of beginning and end of teaching activities	From 01/03/2021 to 11/06/2021
Delivery mode	Traditional
Attendance	not mandatory
Evaluation methods	Oral exam