1212569_21823227.jpg logo_mu_cerne.gif 1212570_28446780.jpg logo_mu_cerne.gif Luděk Bláha, PřF MU Ecotoxic effects - Introduction – OPVK_MU_stred_2 1212569_21823227.jpg logo_mu_cerne.gif CHEMICAL ENTERS THE ENVIRONMENT Bioavailable fraction “EXPOSURE” acute chronic Toxicokinetics biotransformation bioactivation excretion / sequestration Target site LEVELS, FATE, PROCESSES CHEMICAL ENTERS THE ORGANISM biomonitoring 1212569_21823227.jpg logo_mu_cerne.gif WHAT IS LIFE ? • Characteristics & properties of a living entity ? - Structure - Functioning The levels of biological organization - Biology Forums Gallery | Science cells, Biology lessons, Teaching science pinterest.com 1212569_21823227.jpg logo_mu_cerne.gif WHAT IS LIFE ? • WHAT IS ECOTOXIC EFFECT ? 1212569_21823227.jpg logo_mu_cerne.gif Metabolism Control, Interactions with environment Defence against pathogens predators … Defence against toxicants Energy hv food Losses heat faeces Life (maintenance) Growth to sexual maturity Reproduction Chemical stress 1212569_21823227.jpg logo_mu_cerne.gif Metabolism Control, Interactions with environment Defence against pathogens predators … Defence against toxicants Energy hv food Losses heat faeces Life (maintenance) Growth to sexual maturity Reproduction Chemical stress Chemical stress à energy re-allocation à „insufficient“ resourses elsewhere 1212569_21823227.jpg logo_mu_cerne.gif Metabolism Control, Interactions with environment Defence against pathogens predators … Defence against toxicants Energy hv food Losses heat faeces Life (maintenance) Growth to sexual maturity Reproduction Chemical stress Chemical stress + ... another stress (food scarcity) 1212569_21823227.jpg logo_mu_cerne.gif •Ecotoxicologicological effects (see also Bioassays) §Effects on structure §Effects on metabolism (maintenance) §Effects on regulation § § àChanges in functions (e.g. hormones, EE2) àRepair, survival, growth àDeath (lethality) àProliferation = Reproduction Effects at different levels - ORGANISM 3 key apical endpoints (reflected e.g. in regulations) 1212569_21823227.jpg logo_mu_cerne.gif WHAT IS LIFE ? WHAT HAPPENS „BEFORE“ EFFECT MANIFESTATION ? WHAT IS ECOTOXIC EFFECT ? WHAT ARE THE CONSEQUENCES OF THE EFFECT ? 1212569_21823227.jpg logo_mu_cerne.gif Exposure à TK à TD à Effects Escher, B. I., Behra, R., Eggen, R. I. L., Fent, K. (1997), "Molecular mechanisms in ecotoxicology: an interplay between environmental chemistry and biology", Chimia, 51, 915-921. 1212569_21823227.jpg logo_mu_cerne.gif Toxicokinetics à ToxicoDYNAMICS http://4.bp.blogspot.com/-MebbujGDXi0/UAu26D7WxII/AAAAAAAAACk/StePoxIb3Go/s1600/2.png Dynamic simulation of processes causing toxicity and their grouping into toxicokinetics and toxicodynamics, illustrated on the example of the aquatic invertebrate Gammarus pulex. MoA ... and measurable EFFECTS TARGETS = macromolecules (DNA/RNA, proteins, membrane lipids) 1212569_21823227.jpg logo_mu_cerne.gif Target sites = molecules http://www.epa.gov/ncer/rfa/2010/comptox_001.jpg MECHANISMS OF TOXICITY 1212569_21823227.jpg logo_mu_cerne.gif From molecules to individuals à to populations ADVERSE OUTCOME PATHWAYS Models for ecotoxicology and risk assessment. Toxicokinetics are "what the organism does with the chemical" and toxicodynamics are "what the chemical does to the organism". 1212569_21823227.jpg logo_mu_cerne.gif It all starts with MoA = Mechanisms of Action (MoA) •According to target molecules (next slide) –Mechanisms primarily targeting different •BIOLOGICAL MACROMOLECULES –i.e. PROTEINS and/or NUCLEIC ACIDS and/or PHOSPHOLIPIDS •SMALL BIOLOGICAL (ORGANIC) MOLECULES –E.g. Antioxidants or scavengers (vit.E, GSH) • •According to INTERACTION between toxicant/target (next slide) –Non-covalent interactions •Partitioning (v d Waals, H-bonds, hydrophobic interactions) à [1] below •Partitioning with specific steric fit à [3] below –Formation of covalent bonds •... with proteins / DNA-RNA / P-lipids / small molecules à [2] below • •According to “STERIC SPECIFICITY” of the interaction –NON-SPECIFIC MECHANISMS •the interaction between the toxicant and the target occurs “generally” with any target of certain general properties (e.g. toxicant is able to bind to ANY protein having e.g. SH- group), it does not require specific steric (structural) properties of the target –mechanisms [1] and [2] below –SPECIFIC MECHANISMS •the toxicant interacts only with certain and specific structural properties (e.g. specific binding of a pesticide into the active site of enzyme acetylcholinesterase) –mechanism [3] • 1212569_21823227.jpg logo_mu_cerne.gif Target (receptor) in MoA / toxicodynamic = BIOMOLECULE [1] [3] [2] 1212569_21823227.jpg logo_mu_cerne.gif Categorizations of MoAs •[1] non/specific membrane toxicity –Involves ALL ORGANIC compounds –Affinity to non-polar environment (membrane phospholipids) –Two types can be discriminated •nonpolar basal / narcotic toxicity –effects observed at relatively high concentrations, depends on hydrophobicity (Kow) •polar narcosis –more polar compounds may affect also membrane proteins (effects at lower concentrations than expected from Kow) • •[2] nonspecific reactive toxicity –some compounds with “reactive” properties may directly modify biological macromolecule (lipids, proteins, nucleic acids) causing thus toxic effects –reactive chemicals are mostly „electrophiles“ (reacting with „nucleophiles“ in cells – i.e. electrone-rich sites - nucleotides, -NH2, -SH and others), and also toxic (heavy) metals • •[3] specific steric interactions –only certain specific compounds selectively affect specific targets –E.g. enzyme inhibitions (drugs, insecticides); receptor interactions (e.g. Estrogens) –Can be non-covalent as well as covalent –Effects at very low concentrations All organics à membranes Reactive 1212569_21823227.jpg logo_mu_cerne.gif •Student is expected to know principles and some examples of the following main types of toxicity mechanisms • •Membrane nonspecific toxicity (narcosis) • •Proteins and inhibition of enzymatic activities •Ligand competitions – receptor mediated toxicity • •DNA toxicity (genotoxicity) • •Complex mechanisms –Oxidative stress – redox toxicity MoA(s) - toxicity mechanisms - overview 1212569_21823227.jpg logo_mu_cerne.gif The molecular and cellular effects propagate à ORGANISM WHAT (types of) „ORGANISMS“ can be affected by ecotoxicants ? 1212569_21823227.jpg logo_mu_cerne.gif - Structure = TAXONOMY - Functioning = ECOPHYSIOLOGY WHAT (types of) „ORGANISMS“ can be affected by ecotoxicants ? biological classification - Kids | Britannica Kids | Homework Help 1212569_21823227.jpg logo_mu_cerne.gif Community | Definition & Examples | Britannica 1212569_21823227.jpg logo_mu_cerne.gif Ecotoxicity of glyphosate-based herbicide (GBH) to aquatic birds. Direct (continuous arrows) and indirect (dashed arrows) effects of GBH on birds. https://www.intechopen.com/books/biochemical-toxicology-heavy-metals-and-nanomaterials/ecotoxicolog y-of-glyphosate-based-herbicides-on-aquatic-environment 1212569_21823227.jpg logo_mu_cerne.gif 1212569_21823227.jpg logo_mu_cerne.gif Ecotoxicology aims to understand effects of stressors (chemicals) in biological systems à Be aware of life (biological systems) in all types and dimensions à(Eco)toxicological effects are captured (organized) in Adverse Outcome Patways – from Exposures to TK to MoA to „in vivo“ (and beyond) à àThe 3 most important biological endpoints in vivo (apical endpoints) reflected in pragmatic approaches (biotesting) are … WRAP UP = TAKE HOME MESSAGE