Exam #3 Flashcards
What are genes? Function?
Genes - Sequences of DNA that code for proteins.
A gene is a blueprint for how to build a particular protein.
Sex-Linked Traits (sex chromosomes male vs female)
- The sex chromosomes (X or Y)
- Males = XY. Females = XX
- Males have one X chromosome which comes from their mother
- Females have two X chromosomes, one from mom. One from dad. In females, only one X chromosome is active in each cell of the body
Gene X Environment Interactions results (Caspi et al., 2002)
3) Measurements of adult social adjustment
* Antisocial personality, conduct disorder, prone to violence, criminal history
Results
* Interactions of low activity MAO and early life stress predicted poor social adjustment
MAO and Antisocial behavior
1) Childhood experiences of mistreatment were associated with high levels of antisocial behavior (in general)
2) Low activity MAO gene by itself was not linked to more antisocial behavior
3) But…individuals with the low activity MAO gene were more negatively impacted by experiences of mistreatment
* More antisocial behavior
* Genes + childhood stress was best predictor of adult antisocial behavior
Which gene? Serotonin transport and Depression
(Caspi et al., 2003)
Caspi et al, 2003 - Dunedin Cohort
1) Study of childhood maltreatment and adult symptoms of depression
* Long/long (l/l) vs. short/short (s/s) vs. short /long(s/l) alleles
2) Measures
* Childhood maltreatment between ages 3 -11
* Recent life stresses between ages 21 -26
3) Results
* Both childhood maltreatment and recent stresses interact with 5-HTT genes to predict symptoms of depression
* Individuals with two copies of the short serotonin transporter gene were more vulnerable to developing depressive symptoms
* Genes + childhood stress was best predictor of depression in adulthood
DNA Methylation
tag certain genes to be expressed (or not)
* A methyl group (CH3) added to DNA
* Methylation can deactivate (and sometimes activate) genetic expression
* Typically added to the cytosine in DNA (The C’s of the A, C, G, T)
Histone modification?
hide or expose genes by wrapping them around the histone
* Histones are proteins that DNA wraps around
* Histone deacetylase wraps the DNA more tightly which makes the gene inaccessible
Gene X Environment interactions also related to….
Individual differences, Exaggerated vs. Blunted Reactivity
Levine’s (1950) Study of Rat Stress: Early life stress in rats ALL CONSEQUENCES
- Extended separations from mom
- As adult rats —> more stress reactive
- Bigger corticosterone increase in unfamiliar environments
- Greater activation of the CRF system
- Smaller hippocampus
- Dopamine system altered. More likely to consume alcohol.
Levine’s (1950) Study of Rat Stress: Pups exposed to extended separations means?
Pups exposed to extended separations —> more stress-reactive as adults
* Control pups experienced normal amounts of maternal separation
* Some maternal separation is normal when moms forage for food
Stress-reactive rats when placed in unfamiliar environment?
- Large increase in corticosterone when placed in novel environment
- More fearful. Less exploration.
Effects of Early Life Stress on brain of rats
1) More hypervigilant. More reactive to stressors (stress-reactive rats).
2) More corticosterone release in response to stressors
3) More likely to drink water containing alcohol
* Control rats avoided alcohol
Benefits of a Nurturing Mother (ask professor if he’s going to ask beyond the study guide)
- Extended grooming and licking from mom
- As adult rats —> more stress-resistant
- Less corticosterone in unfamiliar environments
- Less activation of CRF system
Cross-fostering studies in rats
1) Pups of stress-reactive mothers “adopted” by stress-resistant moms
2) Pups that received high quality nurture became stress-resistant
* Even if they may have had genetic vulnerabilities to be stress-reactive
Epigenetic influences in rats?
- The experience of receiving quality care did not change the genes
- Changes in gene expression
- Rats that received quality care increased the expression of genes related to serotonin production and decreased expression of CRF
Genetic Vulnerabilities: Bullying and Depression. Gender dif?
- Bullying related to many mental health issues…, especially depression symptoms
Gender differences:
* Boys experience more physical forms of bullying which may peak in childhood
* Girls experience more social and emotional bullying that may peak during adolescence
Relational victimization?
- Social and emotional forms of bullying
- Involves being insults, ostracized, false rumors
- Does not involve physical aggress or harm
- Girls more likely to experience social/emotional bullying than physical
Study methods?
Internalizing vs. Externalizing symptoms
The twin that experienced more bullying between ages 7-9 had more “internalizing symptoms” than the twin that wasn’t bullied
1) Internalizing symptoms:
* Symptoms that primarily impact how the individual feels
* Feelings of sadness, anxiety, loneliness
2) Externalizing symptoms
* Symptoms that impact social interactions with others
* Aggression, disobedience, antisocial behavior
Which gene? transporter? function? Region? which forms?
SERT polymorphisms and depressive symptoms
Polymorphism of the serotonin transporter gene:
* 5-HTTLPR = is the main regulator of serotonin, a polymorphism in the promotor region of the serotonin transporter gene, Serotonin Transporter linked promoter region
* Area of gene that codes for a protein that moves serotonin in/out of the cell
* polymorphism = “different forms”
* The short-form and long-form of the serotonin transporter gene
* The short-form is less effective at making the transport protein (SERT)
Article #5: SERT polymorphisms and HPA axis
Women with two short SERT genes —> increased cortisol reactivity and delayed recovery to psychosocial stressor (mental math)
sources of individual differences
Many ways to be different
* Genes, Anatomy, Physiology, Stress reactivity, Stress recovery…