Lecture 15 (Luckman)

Question 1

Peg3 gene?

Answer 1

Paternally expressed gene 3.

Maternal copy is imprinted to be silenced.

Expressed in maternal hypothalamus, placenta and foetal hypothalamus.

Regulates maternal behaviour and physiology.

imprinted inheritance, so requires paternal inheritance.

Question 2

Peg3 effect on behaviour

Answer 2

maternal care, milk release.

suckling in pup.

Question 3

Peg3 KO in mother

Answer 3

maternal care impaired - time spent retrieving pups increases.
latency of nest building increases.
latency of crouching over pups increases.

impacts litter growth, weight decreases in KO litter. delayed growth, puberty onset and adult reproduction.

Question 4

Peg3 KO pups

Answer 4

Impaired placental growth
Impaired hormonal priming for maternal care and milk let-down.

Delayed growth, puberty onset and adult reproduction

Question 5

Peg3 KO overall effects

Answer 5

The convergent actions of Peg3 in mother and foetus illustrate its functional co-adaptation for the hypothalamus and placenta

Question 6

Peg3 in males

Answer 6

can’t detect estrus cycle.

80:1 likelihood of finding a fertile female.

Question 7

mice estrus cycle?

Answer 7

estrus - when progesterone low ready to be fertilised.

high they are in diestrus state, can’t be fertilised.

if males can detect, pheromones, advantage.

Question 8

peg3 generational?

Answer 8

even if silenced will still be carried to next gen

Question 9

turner syndrome

Answer 9

one x chromosome.

random, not hereditary.

Question 10

turner chromosome karyotype

Answer 10

70% X maternal
30% X paternal

23rd (sexual) chromosome only one X.

nondisjunction during meiosis II. don’t split normally, some cells end up with too few/many X.
when fertilisation occurs, can lead to 1 X.

Question 11

Turner

Answer 11

X chromosome contains approx. 900 genes, while the Y chromosome contains 60 genes.

To maintain relative gene dose equivalence between 46,XY men and 46,XX women, one X chromosome is typically inactivated in women in any given somatic cell.

In Turner Syndrome girls, all cells contain an X chromosome with the same parental origin.

Question 12

turner phenotype

Answer 12

short height.

cardiac abnormalities.

Ovarian failure, therefore no production of sexual steroids.

Absent secondary sexual characteristics during puberty.

May exhibit behavioural abnormalities, including higher prevalence of autism.

Question 13

turner treatment

Answer 13

no cure.

female hormone replace therapy, helps height, can get pregnant.

growth hormone therapy.

regular health checks of heart, kidneys etc.

Life expectancy is slightly reduced.

Question 14

turner cognitive features.

Answer 14

week 15 in gestation, overian failure occurs due to lack of sex steroids.

Executive function is affected, with impairments in attention, working memory, cognitive flexibility and abstract reasoning.

Moderate social impairments including core deficits in recognition of emotional affect, particularly fear and impaired detection of non-verbal cues such as eye gaze.

don’t occur in those with ovarian failure, therefore these cognitive features are likely X-linked in origin.

Question 15

turner girls v boys

Answer 15

girls special education needs higher, also social cognition worse.

Some genes involved in behavioural and social cognitive skills are paternally imprinted.

Hypothesis is that in maternal X, these genes are silenced.

A search is underway to find those genes in the X chromosome.

These data suggest that there are primary (non-hormonal) factors contributing to the difference between the sexes.

Question 16

autism

Answer 16

impaired language.
poor social interaction.
repetitive activies and behaviour.
male increased chance.

Question 17

autism and imprinting.

Answer 17

> 25% turner with ASD.
fragile X syndrome <30%.

linked to X probable.

Question 18

imprinted brain theory of autism.

Answer 18

Badcock and Crespi, 2006

Autism is a disorder of the extreme imprinted brain.

Autism is caused by imbalances that involve increased genetic, neurological and behavioural effects of the paternal brain relative to the maternal brain.

Autism is the consequence of the failure of maternal brain and the impulsiveness, compulsiveness and contrariness of autistics the inevitable result of the paternal brain’s corresponding success.

male>female

Father’s genes motivate self-interested behaviour and use mother’s resources at her expense and that of sibs lacking his genes.

Mother’s genes will be expressed in all her children and will control parts of child brain that can be educated by verbal instruction and practical example.

Less empathetic, more mechanistic, bottom-up and less centrally coherent cognitive style is associated with the paternal brain.

A top-down, contextual, holistic and empathetic cognitive style characterises the maternal brain.

Autism is the consequence of the failure of the maternal brain and success of the paternal brain.