Animal models Flashcards
(29 cards)
Draw a mouse. How many paws does it have?
4, if lucky
What does it mean if the strain is inbred?
it is homozygous at all loci
What does it mean if the strain is outbred?
goal is heterozygosity at all loci
What does it mean if two strains are conplastic?
differ by the MITOCHONDRIA
What does it mean if two strains are consomic?
differ by a single CHROMOSOME
What does it mean if two strains are congenic?
differ by a CHROMOSOMAL STRETCH
What does it mean if two strains are coisogenic?
differ by a single MUTATION
What is a recombinant inbred strain?
differs from each parental strain by half the genome
Inbred strains are generated by mating 1 pair of siblings each generation. How many generations are needed to be allowed to officially call the strain inbred?
20
In outbred strains, we want to get as much diversity as possible, ideally heterozygosity for every locus. How can we achieve that?
a) random mating of >100 breeding pairs
b) rotation systems (>25)
How do you create a consomic strain?
you want a single chromosome from a donor strain
= backcross the recipient strain with a donor strain >10 times
check with the collection of small number of markers and subsequent inbreeding
Who is the mitochondrial donor when creating conplastic strains?
mother in backcrosses
In which disease was it shown that mitochondrial DNA of the mouse strain used influences the immune response?
EAE - model for MS
experimental autoimmune encephalomyelitis
What is the difference between generating consomic and congenic strains?
selection markers
both created by 10+ backcrosses to an inbred strain
How can you create a coisogenic strain?
- introduce the mutation into the genome (by knock in/out, CRISPR…)
- separation from background strain if needed
- inbreeding
Explain how are recombinant inbred strains created. Which project was working on that, what was their aim, approximately how many strains did they create?
- breed 2 parental inbred strains (A and B) -> get AB F1 offspring
- mate siblings (random two)
- continue for 20 generations, until you get fully inbred recombinant strain
Project: collaborative cross Aim: creating novel inbred strains from 8 known strains that would capture 90% of known variation #: ca. 500 (?)
When creating an inbred mouse, why do we need to breed it for so many generations?
after every generation, 12,5 % alleles get fixed (homozygous)
-> after 20 generations, you come to 98,7%
What is the F2 analysis?
finding genetic differences between the offspring with a particularly interesting phenotype and the ones without by inbreeding them until being able to pinpoint a specific allele responsible for it
Name/describe the 5 laws of transplantation (skin).
- isografts (between genetically identical mice) succeed
- allografts fail
- transplanting skin from parent to progeny succeeds, 4. but progeny to parents does not
- progeny is AxB = knows both
- parents are either A or B = one of the MHCs will be recognized as foreign and the graft will be rejected - F2(AxB) or subsequent will more likely than not reject the graft from A (or B)
- original F1 is most diverse
- F2 - Fn crosses are getting more and more inbred
What did Medawar’s, Mitchinson’s and Miller’s experiments show about specificity of tissue rejection?
- immunological memory (second graft of the same kind is rejected faster because memory lymphocytes have been formed against its antigens)
- grafted tissue is recognized with specific receptors
- these receptors are on lymphocytes (if you transfer lymphcytes - not serum only - you get a faster rejection of 2nd graft)
- they are distributed systemically (and are migratory)
- these lymphocytes are T cells (rejection does not happen in neonatally thymectomized animals)
When creating congenic mouse strains for a dominant mutation, what percentage of offspring has a wanted allele fixed?
How many generations are needed to achieve 99,9% homozygosity?
50%
(you either have it or you don’t; and you always backcross with the original background strain)
10 generations
How do you create a congenic mouse strain for a recessive mutation?
What is one of the issues when creating them? Which strain had a problem with this?
Who was a Nobel prize for this awarded to and what did he discover?
cross P0 get F1 -> cross to get F2 choose those who are homozygous for a mutation, cross with background strain again repeat (takes twice as long)
the closer the two genes, the lower the probability of homozygosity (because the recombination frequency between them is lower)
CD45.1 had a new point mutation that was carried on and altered susceptibility to infection with mCMV
Snell -> identified H-2 complex in mice (homologus to HLA in humans)
What happens when:
a) skin transplant between 2 syngenic mice?
b) skin transplant between mice that have the same minor, but different major histocompatibility complex?
c) skin transplant between mice from 2 different strains, but with the same MHC alleles?
d) skin transplant if two mice are identical except for 1 or 2 minor histocompatibility complex loci?
e) skin transplant if two mice are identical except for 3/+ minor histocompatibility complex loci?
a) accepted
b) rejected
c) rejected as in b, because minor antigens are different
d) very slow rejection
e) rejected as in b
Which minor antigen was shown to play a role in human transplants?
male antigen in kidney transplants
male to female transplants were rejected significantly faster
