Aging Flashcards
Aging can be a result of what two things - give examples in organisms
‘wear and tear’ - decline in muscle function in drosophila or teeth worn down in elephants
Genetic - eg salmon die after they lay their eggs
What are the differences in aging between elephants and mice?
Mice live for only 41 months
By the time an elephant is born (gestation = 21 months) a mouse is half way through their life
What is the disposable soma theory?
Natural selection tunes life history of the organism so that sufficient resources are invested in maintaining the repair mechanisms that prevent aging at least until the organism has reproduced and cared for its young
List three senescence factors
DNA damage
Reactive oxygen species
Metabolism
Give three factors which increase life span
Dietry restriction
Enviromental stress
Signals from the somatic gonad
What is the rate of living theory?
Higher metabolism means organisms have a shorter life span
ie larger animals will live longer
whales = 200 years
flies = 150 days
How can drosophila show that a slower metabolism means organisms live longer?
Flies kept at 18 degress will live longer than those living at 29 degrees
18 = 120 days
29 = 40 days
Metabolism is a source of what?
Reactive oxygen species
What happens in worms treated with paraquol or juglone?
They have a longer life span showing they could be superoxide dependent
Contradicts the theory
How does glucose restriction increase lifespan?
It induces mitochondrial respiration increasing oxidative stress
Resistance to oxidative stress is induced by what?
Longevity genes
List some types of progeria syndromes
Hutchinson Guilford Nestor Guillermo Ehlers Danos Cokayne Werner
What is progeria?
Premature aging
What is hutchinson guilford disease?
A lamina mutation = nuclear architecture DNA repair
What is nestor Guillermo?
BANF1 mutation = lamina/mitosis
What is Ehlers Danos a mutation in?
Xylosylprotein 4-beta-galactosyltransferase
What is cockayne?
Group 8 excision repair cross complementing protein = DNA repair
In a non replicating cell DNA damage will cause what?
Aging = senescence
Do mice with higher mutations age quicker?
No
This suggests that damage causes aging in cells
What is PARP?
An enzyme essential for certain DNA repair processes
What happens in mice which are genetically reprogrammed to destroy senescent cells?
They live longer
What is hormesis?
When an enviromental stress activates protective mechanisms
A small insult can unleash a disproportionate protective response
When using forward genetics to identify genes involved in ages what phenotype is looked for and why?
Animals that live longer
Those that live shorter could be due to a variety of mechanisms and so may not be directly linked to aginf
The use of genetics identified which three pathways involved in aging?
IGF
TOR
Sirtuins