Mechanism of Action of Dioxin-Like Compounds

To create differentiated cells in vitro for further toxicity testing

Pluripotent cells, derived from embryos, can divide indefinitely while remaining undifferentiated

Bypassing ethical concerns and enabling personalized analysis of specific diseases

<p>To convert them into a pluripotent state, allowing them to differentiate into any cell type</p> Signup and view all the answers

<p>Enabling direct conversion of one somatic cell type into another without passing through a pluripotent state</p> Signup and view all the answers

<p>By producing a detectable signal, such as fluorescent or luminescent, in response to toxin exposure</p> Signup and view all the answers

<p>Activating the transcription of responsive genes, leading to the production of reporter proteins</p> Signup and view all the answers

<p>By manipulating culture conditions and providing specific signalling cues</p> Signup and view all the answers

<p>To increase water solubility of the substance or introduce functional groups that are more amenable to certain modifications in Phase II.</p> Signup and view all the answers

<p>Incorporating oxygen from O2 into the substrate, often facilitated by cytochrome P450 or flavin monooxygenase (FMO).</p> Signup and view all the answers

<p>The product of Phase I can be very reactive, leading to bio-activation and potentially causing DNA mutations.</p> Signup and view all the answers

<p>Formation of toxic diol-epoxides, leading to local distortion in DNA double helix structure and hampering proper DNA replication.</p> Signup and view all the answers

<p>Coupling of a water-soluble molecule to the handle of the compound, increasing its water solubility and facilitating excretion.</p> Signup and view all the answers

<p>UDPGA</p> Signup and view all the answers

<p>GST</p> Signup and view all the answers

<p>Activation of the AhR pathway leads to the expression of genes involved in xenobiotic metabolism, facilitating the detoxification of pollutants.</p> Signup and view all the answers

<p>A conformational change occurs, allowing the Ah-receptor to translocate into the nucleus.</p> Signup and view all the answers

<p>The expression of CYP1A1 and CYP1B1 enzymes is increased.</p> Signup and view all the answers

<p>Decreased metabolic activity of these enzymes, leading to altered drug metabolism and potentially affecting the efficacy and safety of drugs.</p> Signup and view all the answers

<p>To express the relative potency of individual toxin congeners compared to the most potent TCDD.</p> Signup and view all the answers

<p>The complex formed by the AhR and protein binds to specific DNA sequences, including XREs, activating gene transcription.</p> Signup and view all the answers

<p>Increased expression of enzymes involved in the metabolism and elimination of dioxins themselves.</p> Signup and view all the answers

<p>To allow for the elimination of the accumulated chemical from the fish tissues.</p> Signup and view all the answers

<p>BCF focuses solely on uptake from water, while BAF accounts for all exposure routes.</p> Signup and view all the answers

<p>Trophic magnification (TMF)</p> Signup and view all the answers

<p>Algae → cockles, worms, shrimps, plankton → fish → bird</p> Signup and view all the answers

<p>It allows for the accurate calculation of the bioconcentration factor (BCF)</p> Signup and view all the answers

<p>Through data analysis of fish samples collected at regular intervals during both phases</p> Signup and view all the answers

<p>It results in higher concentrations of substances in their tissues</p> Signup and view all the answers

<p>To ensure the accuracy and reliability of the bioconcentration factor (BCF) results</p> Signup and view all the answers

<p>Bioconcentration refers to the uptake of a chemical from the environment, whereas biomagnification refers to the uptake of a chemical from food.</p> Signup and view all the answers

<p>Biomagnification of DDT leads to higher levels in lactating mothers, potentially harming newborns.</p> Signup and view all the answers

<p>Food is the main route of uptake for biomagnification, allowing higher levels of a chemical to accumulate in organisms.</p> Signup and view all the answers

<p>To determine the bioconcentration factor (BCF) of a chemical in an organism.</p> Signup and view all the answers

<p>Uptake phase refers to the initial increase in chemical concentration, while depuration phase refers to the elimination or clearance phase.</p> Signup and view all the answers

<p>Juvenile fish of a standard species are typically used to provide a standardized and representative model for testing.</p> Signup and view all the answers

<p>BCF ≥ 2000.</p> Signup and view all the answers

<p>Laboratory conditions are necessary to accurately determine the BMF, as they allow for controlled experimentation and minimal environmental variability.</p> Signup and view all the answers

<p>The Koa represents the measure of retention of a compound in air-breathing organisms, which determines the extent of bioaccumulation and biomagnification in these organisms.</p> Signup and view all the answers

<p>The lipid or protein content of diet affects the biomagnification factor (BMF) by influencing the concentration of the pollutant in the food and organism, which in turn affects the bioaccumulation and biomagnification of the pollutant.</p> Signup and view all the answers

<p>Biotransformation is the process by which living organisms chemically modify foreign substances or toxic compounds to make them more water-soluble and easier to eliminate, influencing the rate at which substances are eliminated from the body.</p> Signup and view all the answers

<p>Biomagnification of pollutants like DDT can lead to higher levels of these pollutants in breast milk, posing a risk to the health of nursing offspring.</p> Signup and view all the answers

<p>The food chain plays a critical role in the biomagnification of pollutants, as pollutants accumulate and magnify at each trophic level, resulting in higher concentrations in apex predators.</p> Signup and view all the answers

<p>The OECD 305 BCF test protocol is a standardized test used to measure the bioconcentration factor (BCF) of pollutants, which represents the ratio of the concentration of the pollutant in the organism to the concentration of the pollutant in the surrounding environment.</p> Signup and view all the answers

<p>The bioconcentration factor (BCF) is related to the octanol-air-partitioning coefficient (Koa) in that a higher Koa value indicates a higher potential for bioconcentration, leading to a higher BCF value.</p> Signup and view all the answers

<p>The bioavailable fraction represents the fraction of the pollutant that is freely dissolved in the water phase, which is available for bioaccumulation, and affects the bioconcentration factor (BCF) by influencing the amount of pollutant that can be absorbed by the organism.</p> Signup and view all the answers

<p>Biomagnification occurs primarily through the transfer of persistent lipophilic chemicals from one organism to another through the food chain, resulting in higher concentrations of the chemical at higher trophic levels.</p> Signup and view all the answers

<p>Chemicals with low biotransformation rates, such as persistent lipophilic chemicals, tend to accumulate more in organisms, whereas chemicals with high biotransformation rates are more likely to be eliminated from the body.</p> Signup and view all the answers

<p>Fat content plays a significant role in bioaccumulation, as lipophilic chemicals tend to accumulate in fat tissues, leading to higher concentrations in organisms with higher fat content.</p> Signup and view all the answers

<p>The age and sex of an organism can affect its bioaccumulation potential, with older organisms and females potentially accumulating more lipophilic chemicals due to increased fat content and other physiological factors.</p> Signup and view all the answers

<p>Bioconcentration refers to the accumulation of chemicals from the environment into an organism, whereas biomagnification refers to the increase in concentration of chemicals at higher trophic levels in a food chain.</p> Signup and view all the answers

<p>Lipophilic chemicals tend to accumulate more in organisms due to their ability to dissolve in fat tissues, leading to higher concentrations and potential toxic effects.</p> Signup and view all the answers

<p>Water-soluble and readily biodegradable chemicals tend to cause fewer problems with bioaccumulation due to their ability to be easily eliminated from the body.</p> Signup and view all the answers

<p>The uptake route of a chemical can affect its bioaccumulation potential, with chemicals absorbed through different routes (e.g., dermal, gill, or oral) having varying bioaccumulation potentials.</p> Signup and view all the answers

<p>Koa is a measure of retention of a compound in air-breathing organisms, and it influences the bioaccumulation and biomagnification of pollutants by affecting the passage of pollutants through respiratory surfaces.</p> Signup and view all the answers

<p>The lipid or protein content of diet influences the biomagnification factor (BMF) by affecting the concentration of pollutants in the prey and the predator, and the biotransformation of pollutants in the body.</p> Signup and view all the answers

<p>The biomagnification of pollutants like DDT on lactation in air-breathing organisms can lead to the accumulation of pollutants in milk, which can have adverse effects on the development and health of offspring.</p> Signup and view all the answers

<p>The food chain is critical in the biomagnification of pollutants, as it allows pollutants to accumulate at higher levels in apex predators, which can have adverse effects on their health and the ecosystem.</p> Signup and view all the answers

<p>The bioconcentration factor (BCF) is related to the octanol-air-partitioning coefficient (Koa) in that Koa affects the bioconcentration of pollutants, with higher Koa values indicating higher bioconcentration.</p> Signup and view all the answers

<p>Biotransformation plays a crucial role in the bioaccumulation of pollutants by modifying pollutants to make them more or less bioavailable, and influencing the elimination of pollutants from the body through metabolism and excretion.</p> Signup and view all the answers

<p>The bioavailable fraction is critical in the bioaccumulation of pollutants, as it affects the bioconcentration factor (BCF) by influencing the amount of pollutants available for absorption by organisms.</p> Signup and view all the answers

<p>The process by which the concentration of certain substances increases at higher levels of the food chain is called biomagnification, and it occurs through the transfer of pollutants from one trophic level to the next.</p> Signup and view all the answers

<p>Biomagnification occurs through the transfer of substances from one trophic level to the next when predators consume prey, leading to higher concentrations in higher trophic levels due to slower metabolic rates and accumulation of substances in tissues.</p> Signup and view all the answers

<p>BCF measures uptake from water only, while BAF accounts for all exposure routes; BAF is a more comprehensive measure of bioaccumulation, highlighting the importance of considering multiple exposure routes in ecotoxicology studies.</p> Signup and view all the answers

<p>A steady state is necessary to ensure that the chemical concentration in the fish tissue has reached equilibrium with the surrounding water, allowing for the accurate calculation of the BCF as the ratio of the chemical concentration in the fish tissue to the concentration in the water.</p> Signup and view all the answers

<p>Analytical quality control measures are essential to ensure the accuracy and precision of the chemical concentration measurements in the fish tissues and water, and to prevent errors or contamination that could affect the validity of the test results.</p> Signup and view all the answers

<p>Slower metabolic rates in organisms at higher trophic levels lead to slower elimination of pollutants, resulting in higher concentrations and accumulation of pollutants in these organisms, contributing to trophic magnification.</p> Signup and view all the answers

<p>Bioconcentration refers to the uptake of pollutants from the surrounding environment, while biomagnification refers to the increase in pollutant concentration at higher trophic levels due to the transfer of pollutants through the food chain; both processes contribute to the accumulation of pollutants in organisms.</p> Signup and view all the answers

<p>The food chain allows for the transfer of pollutants from one trophic level to the next, facilitating biomagnification; this process is significant in ecotoxicology as it can lead to high concentrations of pollutants in apex predators, posing risks to human health and the environment.</p> Signup and view all the answers

<p>The TMF is a measure of the increase in pollutant concentration at higher trophic levels, and is a critical indicator of the bioaccumulation of pollutants in food chains; it provides a quantitative measure of the biomagnification of pollutants.</p> Signup and view all the answers