Lecture 7: Transgenic Technology Flashcards
SZ pos and neg symptoms
negative
- decrease in emotional range
- poverty of speech
- loss of interest or drive
positive
- hallucinations
- delusions
- disorganized speech and behaviour
Features of SZ
- 0.5 to 1 % of pop
- onset is later in females
- associated with disrupted neurotransmission (treated with DA antagonists)
- h2 of 0.6-0.7
environmental risk factors for Sz
winter birth, urban env, maternal depression, Rh incompatibility, etc
DISC1
disrupted in SZ gene
- produces a protein involved in neuronal proliferation, differentiations, and migration (which is consistent with idea of NDD (neuro-develo disorders)).
- variants of this gene assoc with SZ in humans and animals
- translocation between chromosomes 1 and 11
Why are boys more affected by ASD than girls
- harder to diagnose in women
- higher genetic load may be required in women (controversial)
- risk variants interact w sexually dimorphic pathways
- sex-specific methylation patterns
Genetic basis of ASD
- h2 = 0.6 to 0.7 (comparable to SZ)
- 102 genes associated with autism, 53 also overlap with other NDDs
- findings consistent with liability threshold model (17-52% of variation in trait is associated with common SNPs)
- rare variants and CNVs are associated with the disorder
ASD and SZ overlap
CNVs in 8 loci w 47 genes are common to ASD and SZ
BP is more common in
creative professionals and individuals with arts education
Polygenic risk scores for BP and SZ predict
creativity
Personality disorders
inflexible patterns of behaviour that lead to distress in a wide variety of cases
- emerge in adolescence with other personality traits
- less researched
- difficult to reliably diagnose
Psychopathic traits are present in around… of the pop but… in incarcerated pop
- 1%
- 10-30%
Env and genetic risks of psychopathy
env - early trauma, exposure to violence, brain damage to OFC, poor parental relationship
genetic - up-regulation in certain genes might be critical and MAO and 5-HTTLPR may be involved
Polygenic risk scores for one disorder also predict other disorders. Which ones? And what does this imply?
SZ and BP
implies there’s a shared genetic basis
CACNA1C
gene for L-type voltage-gated calcium channel subunit
- linked to multiple disorders
- animal studies suggest these genes play a key role in brain development
- genes linked to psychiatric disorders tend to be enriched in developing brain
Overlap between disorders and other traits
- there is overlap between NDDs and things like college attainment, years of education, intelligence, fertility even (reduced fertility)
Why transgenic mice
- synteny
- cheap/easy to maintain (breed quickly and are small and have large litters)
Homologous recombination: positive and negative selection
positive - include neomycin resistance gene (only cells that underwent successful recombination and have GOI and bacterial resistance gene will survive)
negative - include DNA sequence for diptheria toxin outside homology arms (random insertion will result in diptheria toxin being incorporated)
Chimeric blastocyst
normal blastocyst that is injected with cells that have been genetically modified. some of the cells in the pups will be from normal es cells and some will be genetically modified.
Homologous recombination technique
- produce targeting vector with GOI
- harvest a blastocyst from a female after mating
- culture ES cells from blastocyst
- electroporate vector into ES cells
- out of ES cell pop, select for cells that have incorporated the vector (pos or neg selection)
- harvest a new blastocyte from a female mouse after mating and implant targeted ES cells into blastoc.
- implant it back in pseudopreg mouse and wait for chimeric pups to be born.
- mate chimeric pups with albino mice and look for pure agouti offspring (know that they got a gamete that was pure agouti)
- do a PCR test on agouti pups to verify desired genetic change (now have a founder line)
Conditional model
transgenic model that restricts changes in the genes to a specific cell type
- uses cre recombinase that recognizes two lox p sites in DNA and excises out the DNA flanked by the sites
How to knck out NR1 gene in CA1 cells of hippocampus
- generate transgenic nice with a loxP site on either side of NR1 gene
- in cells that express cre the nr1 gene will be excised
- generate transgenic mice that only express cre in CA1 cells (link Cre to a promoter specific to CA1 pyramidal cells ex. CAMKII promoter)
- cross both strains of mice
