MindMap Gallery environmental toxicology
In environmental toxicology, mutations are spontaneous mutations (evolution of species) and induced mutations (breeding of new varieties), and the types of mutations are gene mutations and chromosomal aberrations (changes in chromosome structure and number).
Edited at 2023-10-21 11:06:15This is a mind map about bacteria, and its main contents include: overview, morphology, types, structure, reproduction, distribution, application, and expansion. The summary is comprehensive and meticulous, suitable as review materials.
This is a mind map about plant asexual reproduction, and its main contents include: concept, spore reproduction, vegetative reproduction, tissue culture, and buds. The summary is comprehensive and meticulous, suitable as review materials.
This is a mind map about the reproductive development of animals, and its main contents include: insects, frogs, birds, sexual reproduction, and asexual reproduction. The summary is comprehensive and meticulous, suitable as review materials.
This is a mind map about bacteria, and its main contents include: overview, morphology, types, structure, reproduction, distribution, application, and expansion. The summary is comprehensive and meticulous, suitable as review materials.
This is a mind map about plant asexual reproduction, and its main contents include: concept, spore reproduction, vegetative reproduction, tissue culture, and buds. The summary is comprehensive and meticulous, suitable as review materials.
This is a mind map about the reproductive development of animals, and its main contents include: insects, frogs, birds, sexual reproduction, and asexual reproduction. The summary is comprehensive and meticulous, suitable as review materials.
Key Chapters (Chapter 5)
mutagenicity test
mutation
Spontaneous mutation (evolution of species) and induced mutation (breeding of new varieties)
Types of mutations: Gene mutations and chromosomal aberrations (changes in chromosome structure and number)
Mechanism: DNA-targeted damage: genetic mutations and changes in chromosomal structure Damage not targeting DNA: changes in chromosome number
Factors causing genetic mutations physical factors chemical factors biological factors age factor genetic factors
Gene mutation: base substitution, frameshift mutation
Chromosome mutation: Abnormal chromosome number (deletion, duplication, rearrangement of chromosome structure), chromosome structural aberrations
1) In vitro/in vivo gene mutation test
1. In vitro gene mutation test: Salmonella typhimurium/lactation microsomal enzyme test (Ames test), mammalian somatic cell strain mutation test 2. Gene mutation test in vivo ◇ Dominant lethal mutation test, Drosophila sex-linked recessive lethal test (SLRL)
(2) In vitro/in vivo DNA damage test
1. In vitro/in vivo sister chromatid exchange test (SCE) 2. In vitro/in vivo unprogrammed DNA synthesis test (UDS test)
(3) Chromosome aberration test in vitro/in vivo
1. In vitro chromosome aberration test: chromosome aberration analysis of mammalian cells or human lymphocytes cultured in vitro, peripheral blood lymphocyte micronucleus test 2. In vivo chromosome aberration test: in vivo chromosome aberration analysis of rat or mouse bone marrow cells, animal polychromatic erythrocyte micronucleus test
AMES experimental standard strains: TA98, TA97, 7A100, 7A102 (containing not only his mutations but also additional mutations)
Preparation of bacterial liquid and identification of bacterial strains
Histidine requirement, deep roughness requirement, UV sensitivity, spontaneous reversion
Result evaluation: point method, infiltration method
Experimental advantages and disadvantages
Features: ① Advantages: simple, sensitive, fast (48h), low cost The test results are consistent with the mutagenicity rate in animals up to 90%
② Disadvantages: Using microorganisms as test substances cannot fully reflect the genetic information of mammals. The DNA repair system of microorganisms is different from that of animals. Microorganisms have no immune system. A small number of foreign compounds that are not transformed in the liver cannot be detected by this method.
Commonly used experimental cell lines: Chinese hamster lung cell v97, Chinese hamster ovary cell (CHO) cell line, mouse lymphoma cells
In vivo genetic mutation testing
(Drosophila sex-linked invisibility experiment) (SLRL experiment)
Test methods: selection of experimental fruit flies, palatability test, toxicity test, fecundity test, mutagenicity test
principle
method
Dominant lethal mutation experiment ()
DNA damage assay
Sister chromatid exchange experiment (SCE) principles and methods
Principles and methods of unprogrammed DNA synthesis experiment (UDS)
Chromosome aberration experiment
Test methods: Chromosome aberration experiments in in vitro cultured mammalian or human lymphocytes and in vivo chromosome experiments in rat or mouse bone marrow cells
micronucleus test
Bone marrow polychromatic erythrocyte micronucleus test (PCE)
Route of exposure: intraperitoneal injection
Teratogenicity test
Toxicological characteristics of teratogenic effects
Embryos in the organogenesis period are most sensitive to teratogens. When a teratogen comes into contact with the embryo during the sensitive period, it can cause different malformations depending on whether the embryo is at different stages of development (a few days after conception).
Species differences and individual differences are more obvious in teratogenesis 1. They may not all have teratogenic effects in different animals, and the types of malformations they cause may not be the same. 2. Interspecific differences, that is, differences between different strains of the same species, are also very obvious in teratogenic effects.
The relationship between dose and effect is complex 1. The dose-effect relationship is complex and has different causes. 2. The dose-response curve of teratogenic effects is relatively steep, that is, the teratogenic zone is relatively narrow. 3. There are still different opinions on the maximum no-effect dose of teratogenic effects.
teratogenic mechanism
(1) Mutations cause abnormal embryonic development (2) Enzymes that play an important role in development are inhibited or destroyed, affecting the normal development of the embryo, resulting in embryonic malformations (3) Interfering with maternal homeostasis (4) Disorders in the cell division process
Experimental Methods Animal Selection
Carcinogenicity test
basic concept:
Chemical carcinogenesis refers to the process by which chemicals (including organic, inorganic, natural and synthetic chemicals) cause tumors. Chemical carcinogens refer to chemicals that can induce tumors.
Characteristics of chemical carcinogens Most are electrophiles, a class of compounds with electrophilic groups in their molecular structure Affected by factors such as species, strain, gender and environment. There is a dose-response relationship Biological effects are persistent and delayed In animal experiments, when the doses are equal, the effect of administering the test substance multiple times is greater than that administered once. Generally related to the interaction with the genetic material of the host cell or other cellular macromolecules
Mechanism of action of chemical carcinogens
Somatic mutation theory: Carcinogenic factors act on the genetic material DNA of somatic cells, causing them to mutate. As a result, the functions of the cells undergo abnormal mutations and cause cancer, that is, carcinogenesis.
Differentiation Disorders Theory Cell canceration does not necessarily require mutations in the genetic material of somatic cells, but only the relevant gene regulation processes during cell differentiation are interfered by carcinogens, causing cell differentiation and proliferation to become disordered and canceration occurs.
oncogene theory Proto-oncogenes are present in the DNA molecules of all cells. In normal cell genomes, they play a major role in regulating normal life activities of cells. Once these genes mutate or are abnormally activated, cells can undergo malignant transformation.
multi-stage theory
1. Initiation stage The process in which carcinogens interact with a certain tissue leads to the production of "initiating cells (or activated cells)", also known as the priming stage. Substances that can cause "primer cells" to be produced are called "initiators". 2. Growth promotion stage ◇The process of promoting the expression of the phenotype of the initiating cells at the tissue level is the proliferation stage of cancer; chemicals with growth-promoting effects are called growth-promoting agents or cancer-promoting agents. The growth-promoting stage takes a long time. It is reversible in the early stage and irreversible in the late stage. Chemicals that have both initiating and growth-promoting effects are called complete carcinogens, while chemical carcinogens that only have initiating effects are called incomplete carcinogens. 3. Invasion and metastasis stage (progression stage) Established cancer continues to develop, gradually invading surrounding normal tissues, and spreading to distant locations, which is irreversible.
Experimental advantages: the test period is short, economical and convenient; experimental disadvantages: it cannot fully reflect the physiological and metabolic effects of the whole animal
Chapter 6 (Toxicological Safety Evaluation of Chemical Substances)
Principles for selecting safety evaluation experiments
Select the corresponding toxicology experiment according to the type of test substance
An experiment with short cycle, low cost and high predictive value
Preparation before experiment
Collect basic information about the test substance (chemical structure, physical and chemical properties and purity, application of the test substance)
Selection of test samples and experimental animals
Production process, ingredient specifications, property differences
Summary of key knowledge (Chapter 10)
Classification of endocrine disruptors: pesticides, industrial compounds, phytoestrogens
The mechanism of action of organochlorine pesticides
The main manifestations are damage to the central nervous system, including headache, dizziness, blurred vision, nausea, vomiting, salivation, diarrhea, and general weakness in mild cases. In severe cases, paroxysmal and tonic convulsions may occur, and even death due to loss of consciousness.
DDT degrades into low-toxic DDE, DDD and non-toxic DDA in the environment (DDA is a carboxylic acid substance, soluble in water and excreted in urine)
The mechanism of action of organophosphorus pesticides
A small amount of organophosphorus will not be toxic after being absorbed by the human body, but when too much is taken in, it will still have effects.
How does carbamic acid work?
Acute poisoning manifests as salivation, tearing, muscle tremors, pupil constriction, deep paralysis, difficulty breathing, and severe convulsions and death.
Proposed chamethrin pesticides
Mild cases include headache, dizziness, nausea and vomiting, severe cases include listlessness, irritability, and coma.