lecture 3 Alternative models Flashcards
advantages of traditional models of aging
-short lifespans
-availability of well-defined strains (many with different longevities)
-genome and transcriptome
-genome editing tools
animal husbandry: controlled management and production of the animals,
negligible Senescence examples
hydra, some jellyfish species, bristlecone pine
animals with unusual lifespans?
naked mole rat
birds
mice and rats (Advantages)
mammalian aging, share (with humans) many aging processes
-cardiomyocyte loss, muscle loss, muscle fiber loss
-available in large numbers, numerous strains (differing longevity)
-environmental control: diet, temperature, monitor activity, lack of infections, parasites
-genetic manipulation (transgenics)
-defined and known lifespan for many of the strains
What animals are not good models for neurodegeneration?
non-transgenic mice and rats are not good models of neurodegeneration because they normally do NOT develop Alzheimer’s disease
-there is considerable use of transgenic mice and rats to model species associated with neurodegeneration
e.g. expression of human amyloid precursor protein (hAPP) and beta-amyloid (AB)
APP/PS1: early-onset AD model
-expressed chimeric mouse/human amyloid precursor protein and a mutant human presenilin 1 (PS1)
is the exclusive use of rodent models the best way to study aging?
would be like attempting to study a broad category on the same two people forever repeating this, so probably not
Greenland shark (Somniosus microcephalus)
lifespan: 272-500 years
sexual maturity (females): approx 150 years
length: 6 metres
slow growth, slow movement only 2.9 km/hr compared to most sharks going 8km/hr
Reasons NOT to study longest lived species
-often have large body mass
-environmental control difficult or impossible to control
-diet, caloric intake, temp, external stress, predation/accidental death, metabolic rate
-rare species- very few animals to study
-longitudinal study often impractical
Reasons to study longest-lived species
makes intuitive sense
-something is allowing for those animals to survive for extended periods
-longitudinal possible for some
-housing (controlled environment) possible
-non-rodent studies needed
Hydra
adults have abundant stocks of adult stem cells–> maintenance of regenerative capacity
Hydra oligactis - when induced to a different temperature of 10 degrees showed signs of aging
-if you change the temperature they go from immortal to senescent
-they are able to do this because of STEM cells
what two things are of greater priority to an organism than repair?
metabolism and reproduction
Bristlecone pines
estimated maximum lifespan: 5000 years
the concept of senescence does not apply to these trees
-longevity is unaccompanied by the deterioration of meristem function in embryos, seedlings or mature trees
Alerce tree, Gran Abuelo (Chile)
known as the great grandfather tree, the oldest living individual on earth
is older than the Methusaleh (bristlecone pine)
new models for aging
animals with an extended lifespan
vertebrates with the short lifespan
animals with unusual aging e.g negligible senescence
mammals with unusually aging - longer lifespan than expected
turquoise killifish
shortest-lived vertebrate in captivity
wide set of aging phenotypes including cancer
sequenced genome
efficient transgenesis
Planarian
-potentially immortal lifespan
-pluripotent adult stem cell
-capable of whole body regeneration
-can perform RNAi screens
-if you chopped it in half, you would have two functioning planaria