Lecture 7: Transgenic Technology

Question 1

SZ pos and neg symptoms

Answer 1

negative

• decrease in emotional range
• poverty of speech
• loss of interest or drive

positive

• hallucinations
• delusions
• disorganized speech and behaviour

Question 2

Features of SZ

Answer 2

• 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

Question 3

environmental risk factors for Sz

Answer 3

winter birth, urban env, maternal depression, Rh incompatibility, etc

Question 4

DISC1

Answer 4

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

Question 5

Why are boys more affected by ASD than girls

Answer 5

• 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

Question 6

Genetic basis of ASD

Answer 6

• 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

Question 7

ASD and SZ overlap

Answer 7

CNVs in 8 loci w 47 genes are common to ASD and SZ

Question 8

BP is more common in

Answer 8

creative professionals and individuals with arts education

Question 9

Polygenic risk scores for BP and SZ predict

Answer 9

creativity

Question 10

Personality disorders

Answer 10

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

Question 11

Psychopathic traits are present in around… of the pop but… in incarcerated pop

Answer 11

• 1%

- 10-30%

Question 12

Env and genetic risks of psychopathy

Answer 12

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

Question 13

Polygenic risk scores for one disorder also predict other disorders. Which ones? And what does this imply?

Answer 13

SZ and BP

implies there’s a shared genetic basis

Question 14

CACNA1C

Answer 14

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

Question 15

Overlap between disorders and other traits

Answer 15

• there is overlap between NDDs and things like college attainment, years of education, intelligence, fertility even (reduced fertility)

Question 16

Why transgenic mice

Answer 16

• synteny

- cheap/easy to maintain (breed quickly and are small and have large litters)

Question 17

Homologous recombination: positive and negative selection

Answer 17

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)

Question 18

Chimeric blastocyst

Answer 18

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.

Question 19

Homologous recombination technique

Answer 19

1. produce targeting vector with GOI
2. harvest a blastocyst from a female after mating
3. culture ES cells from blastocyst
4. electroporate vector into ES cells
5. out of ES cell pop, select for cells that have incorporated the vector (pos or neg selection)
6. harvest a new blastocyte from a female mouse after mating and implant targeted ES cells into blastoc.
7. implant it back in pseudopreg mouse and wait for chimeric pups to be born.
8. mate chimeric pups with albino mice and look for pure agouti offspring (know that they got a gamete that was pure agouti)
9. do a PCR test on agouti pups to verify desired genetic change (now have a founder line)

Question 20

Conditional model

Answer 20

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

Question 21

How to knck out NR1 gene in CA1 cells of hippocampus

Answer 21

• 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