Transcript Outlines Might Include

Mutagens
• Definition: an ‘agent’ that causes heritable
changes in the genetic information
• Changes may be transitions, transversions, deletions,
insertions, chromosomal aberrations (clastogens break
chromosomes)
• Agents may be chemical, radiation, including UV light, heat,
transposons or insertion elements
• Somatic mutations pass to daughter cells, germline mutations
pass to offspring
Detecting mutagens
• Mutations can occur spontaneously, without an external cause, thus
mutagens must increase the frequency of changes above background:
Common tests include:
– Ames test (his- Salmonella revert to his+ as seen on minimal medium
on plates
– Fluctuation test, same, but done in liquid in 96 or 384 well plates
– Drosophila ClB and Muller techniques for chromosome-wide tests
– In vitro (tissue culture using mouse lymphoma TK+ cells): if TK gene is
mutated, cells survive in presence of trifluorothmidine
– Micronucleus assay: occurs when chromosome fragments are present
during mitosis
– Rodent cancer induction
Example Tests
Ames
Ames test
Fluctuation test
Micronucleus test
Teratogens
• Defined as ‘agents’ that causes developmental
abnormalities
– In animals exposure occurs in utero
– May be chemical, viral, heat, radiation etc., but by
definition, does not indicate that a mutation has taken
place
– Often detected after the fact based on epidemiological
studies/databases
– Current tests include zebrafish development and human
pluripotent stem cell test (hPST)
Endocrine Disruptors
• Defined as chemicals that alter normal hormone regulation
– Hormones and hormone receptors are the key to regulation of many
biological processes
• Estrogens
• Androgens
• Thyroid
• Screening and detection
– High throughput screening of potential compounds based on binding
to specific receptors (estrogen receptor, etc)
– Reproduction in mud snails (estrogen related)
– Reporter gene expression assays
– Whole genome expression profiling in TE671 cells (human
medulloblastoma)
– Frog sex changes?
Reliable Sources?
• Scientific papers can be: increase finding these
by searching at:
– Google Scholar
– NCBI search
• multiple databases searched
• ‘advanced’ allows to narrow by combining terms
– EPA site has search function
Example of actual data:
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Nature and structure of agent
Natural or manmade
Intended purpose/use
History of use/occurrence/problems
Basis for concern in the environment
Controversies/web-social media etc
Control measures
Data-based Evidence for/against
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Nature and structure of agent
Natural or manmade
Intended purpose/use
History of use/occurrence/problems
Basis for concern in the environment
Evidence for/against
Control measures