Chapter 3. Biology and Diseases of Mice Flashcards
What is the scientific classification of the laboratory mouse?
Order Rodentia Superfamily Muroidea Family Muridae Subfamily Murinae Genus Mus Clade M. musculus, collectively called the 'house mouse'
What is the native range of the genus Mus?
Eurasia and North Africa
What is an ‘aboriginal’ species?
Species that lives independent of humans.
Species of the genus Mus have been classified as either aboriginal or commensal
What is a ‘commensal’ species?
Species that have coevolved and geographically radiated with human civilization since the dawn of agriculture 12,000 years before present (bp).
(Species of the genus Mus have been classified as either aboriginal or commensal)
What is the origin of the genus name “Mus”?
From Sanskrit, Mush: to steal.
Where did the progenitor of the M. musculus clade arise?
Northern Indian subcontinent. Diverged into genetically isolated and distinct species or subspecies due to geographic barriers (mountain ranges). There is debate over whether the taxa in this clade are species or subspecies, and some have referred to them an ‘incipient species’, but their genetic divergence is blurring as they colonize the world and hybridize.
What is an incipient species?
A group of a particular species that are about to become genetically isolated from the rest of the species, though at this time can still reproduce with other groups of the species before their gene pools become too distinct.
What is the approximate percentage make-up of different M.m. species in the laboratory mouse genome?
~60% M.m. domesticus
~30% M.m. musculus
~10% M.m. castaneus
Where did the M.m. musculus and M.m. castaneus contributions to the laboratory mouse genome originate from?
Primarily derived from M.m molossinus Japanese fancy mice.
M.m. domesticus
Indigenous to western Europe and southwest Asia.
M.m. musculus
Indigenous to eastern Europe and northern Asia.
M.m. castaneus
Indigenous to southeast Asia.
M.m. molossinus
Indigenous to Japan and the Korean peninsula.
Describe the history of Asian ‘fancy mice’.
The cohabitation of humans with commensal mice gave rise to captive breeding for coat color and behavioral variants in China over 3000 years ago. By the 1700s, mouse ‘fanciers’ in Asia had created many varieties of fancy mice, as did European fanciers, who subsequently acquired Asian stocks, esp. Japanese M.m. molossinus to mix with European M.m. domesticus.
Most laboratory mouse strains are closely genetically related, since many were derived from a genetically mixed but small number of fancy mice from which singly mouse breeder at the beginning of the 20th century?
Abbie Lathrop’s Granby Mouse Farm, Massachusetts
Most inbred lab mice share a common maternal mitochondrial genome derived from _______ and a common Y chromosome contributed by _______.
Maternal mitochondrial genome = M.m. domesticus.
Y chromosome = M.m. musculus, through its contribution to the genome of M.m. molossinus.
C57BL/6 mice contain minor genetic elements from what mouse species?
M. spretus.
Name wild aboriginal species of mice that are not members of the M. musculus clade, but have been used to establish inbred lines of mice.
M. spretus.
M. caroli
Abbreviation 129: A
A strains
Abbreviation 129: AK
AKR strains
Abbreviation 129: B
C57BL strains
Abbreviation 129: B6
C57BL/6 substrains
Abbreviation 129: B10
C57BL/10 substrains
Abbreviation 129: BR
C57BR strains
Abbreviation 129: C
BALB/c strains
Abbreviation 129: C3
C3H strains
Abbreviation 129: CB
CBA strains
Abbreviation 129: D
DBA strains
Abbreviation 129: D1
DBA/1 substrains
Abbreviation 129: D2
DBA/2 substrains
Abbreviation 129: HR
HRS strains
Abbreviation 129: L
C57L strains
Abbreviation 129: R3
RIIIS strains
Abbreviation 129: J
SJL strains
Abbreviation 129: SW
SWR strains
What were the first autosomal linked mouse genes found to be linked in 1915?
Albino and pink-eyed dilution
How many pairs of chromosomes do mice have?
20 telocentric chromosomes in their haploid genome (40 chromosomes in all).
Differentiated by size and patterns of transverse bands. Designated by Arabic numbers in order of decreasing size.
In the 1970s, chromosome rearrangements were used to assign known genetic linkage groups - designated by Roman numerals - to specific chromosomes and for determining locus order with respect to the centromere.
What lab technique can be used to physically locate genes on chromosomes?
Fluorescent in situ hybridization (FISH)
Quantitative trait loci (QTL)
Chromosomal regions containing genes that influence a quantitative trait.
This methodology has allowed for mapping genes and identifying similarities between mouse and human genomes.
Histocompatibility complex
One of the most thoroughly studied genetic systems of the mouse.
Histocompatibility (H) loci control expression of cell surface molecules that modulate critical immune responses.
On what chromosome is the major histocompatibility complex (MHC) located in mice?
Chromosome 17.
H2 complex
Mouse major histocompatibility complex genes are arranged in a complex gene cluster - the H2 complex, coding for proteins either directly performing or associated with antigen presentation to T lymphocytes.
Several loci, including K, D, L, I-A, I-E.
Minor H2 loci groups are scattered throughout the genome and are responsible for delayed graft rejection.
Genes associated with the H2 complex also control other immunological functions - cell-cell interactions in primary immune responses, level of response to a given antigen, immune-mediated responses to infectious agents such as viruses and complement activity.
H2 haplotypes
Inbred strains of mice, being homozygous, each have unique sets of H2 alleles, termed H2 haplotypes.
BALB H2 haplotype = H2^d
C57BL H2 haplotype = H2^b
International ImMunoGeneTics (IMGT) Information System
Provides details on H2 haplotypes for various inbred mice.
International Mouse Genome Sequencing Consortium
Developed a robust physical map and high-quality genome sequence of the C57BL/6J mouse in 2002.
Mouse Genomes Project/Wellcome Trust Sanger Institute
Extending mouse genome sequencing effort to include the genome sequences of 17 key mouse strains.
European Nucleotide Archive
Completed and evolving mouse sequence data is available through this archive.
Mouse Genome Informatics database
Inbred mouse strains, natural mutants, induced mutants, transgenic lines, and targeted mutant lines of mice are catalogued.
Mutant Mouse Regional Resource Centers
In the US, there are four regional NIH-supported centers, which link to international mouse repositories in Europe, Japan, Canada, China, and Australia, as well as additional resources programs in the US through the International Mouse Strain Resource.
International Mouse Strain Resource (IMSR)
For depositing, archiving, and distributing mutant mouse and embryonic stem cell lines to the scientific community.
Which groups are working on three major targeted gene knock-out programs, all utilizing C57BL/6N embryonic stem cells?
Funded by the NIH, the European Community, and Genome Canada.
Knock Out Mouse Project (KOMP), the European Conditional Mouse Mutagenesis Program (EUCOMM), and the North American Conditional Mouse Mutagenesis Project (NorCOMM).
What are the three distribution centers for the targeted knock-out programs with C57BL/6N embryonic stem cells?
Mouse lines will be available through:
German Resource Center for Genome Research (RZPD), the KOMP repository, and the Canadian Mouse Consortium (CMC).
The repositories are all linked to IMSR, and provide access to mice, germplasm, genomic detail, and phenotypic data.
International Mouse Phenotyping Consortium (IMPC) and the Mouse Genome Database (MGD)
Genetic, genomic, and biological data on mice are available through these groups.
C.C. Little
Developed the first inbred mouse strain (DBA) in 1909
Strains
Term for inbred mouse strains
Achieved by 20 or more brother x sister (filial) generations.
Isogenic OR Syngenic
Genetically identical
Mice within an inbred strain are isogenic or syngenic to other mice of the same strain and sex.
When is a mouse strain FULLY inbred?
Because of residual heterozygosity, a strain is not fully inbred until after 60 filial (F) generations.
Most commonly used inbred strains represent 200 or more F generations.
Substrain
When branches of an inbred strain are separated, spontaneous mutations, residual heterozygosity, and retroelement integrations results in genetic differences.
Branches of an inbred strain become SUBSTRAINS if:
1) They are separated before F40
2) If branches have separated for 100 generations
3) If genetic differences arise
Recombinant inbred
RI strains are sets of inbred strains of mice derived from crossing two inbred strains, and developed by single pair random matings of sibling mice from the F2 generation, thereby creating separate breeding lines.
When two inbred strains are crossed, the F1 hybrids are genetically identical (isogenic) but maximally heterozygous (with chromosomes of each chromosomal pair separately contributed by each parent strain). F2 hybrids are maximally genetically diverse from one another (with chromosomes of both chromosomal pairs containing a mixture of contributions from each parental strain). With subsequent F generations, mice once again approach inbred status. This technique is used for creating recombinant inbred (RI) strains.
Describe the separate breeding lines for recombinant inbred strains.
Each line created is maintained separately, and then propagated by brother-sister matings for 20 generations, with each line becoming a separate inbred strain, but belonging to a set of recombinant inbred strains.
Recombinant inbred sets are generally limited to two parental strains.
What is the benefit of using recombinant inbred strains?
Recombinant inbred mice are useful for mapping phenotypic or quantitative traits that differ between the progenitor strains.
Collaborative Cross mice
An international effort to increase allele diversity among recombinant inbred strains by creating the Collaborative Cross - a panel of recombinant inbred strains being generated by mixing the genomes of eight disparately related inbred strains.
Which 8 mouse strains are part of the Collaborative Cross?
A/J, C57BL/6J, 129S1/SvImJ, nonobese diabetic (NOD)/ShiLtJ, NZO/HILtJ, CAST/EiJ, PWK/PhJ, and WSB/EiJ.
These 8 strains capture nearly 90% of the known genetic variation present among laboratory mice.
Recombinant congenic strain
Sets of inbred strains derived in a manner similar to that for recombinant inbred strains, except that one or more backcrosses to one parental strain (designated the background strain) are made after the F1 generation, before inbreeding has begun.
The other parental strain is designated the donor strain.
What determines the proportion of background strain and donor strain genomes in a recombinant congenic strain?
The number of backcrosses proceeding inbreeding.
Advanced intercross lines (AIL)
A type of recombinant inbred line. Made by producing an F2 generation between two inbred strains and then, in each subsequent generation, intercrossing mice but avoiding sibling matings. This increases the possibility of tightly linked genes recombining.
What is the purpose of advanced intercross lines?
To increase the possibility of recombination between tightly linked genes.
Co-isogenic
When a mutation arises spontaneously or is induced within an inbred strain, that mutant mouse becomes co-isogenic with the parental inbred strain, being virtually identical except for the single mutant allele.
Backcrossing
If a mutation that arose in one inbred strain is desired within the background of another inbred strain, this is accomplished by backcrossing - an F1 hybrid is created by mating the donor mutant strain to the desired background strain, with subsequent matings to the background strain while retaining the mutant locus.
Congenic
Strains that are genetically identical except for one mutant locus.
An F1 hybrid is created by mating the donor mutant strain to the desired background strain, with subsequent matings to the background strain while retaining the mutant locus. After 10 backcross generations, the mutant mouse line is congenic to the background inbred strain.
Are congenic mice ever co-isogenic?
No, as the preserved mutant locus in a congenic mouse is invariably surrounded by flanking DNA, which may significantly influence phenotype.
Stock
The name for outbred mice.
Defined as a closed population (for at least four generations) of genetically variable mice that are bred to maintain maximum heterozygosity.
Outbreeding
Can only be achieved with a large breeding population using a systematic breeding scheme, or randomized selection of breeders from the population.
Ex: in a population of 25 breeding pairs, heterozygosity will decrease at 1% per generation with standard randomization techniques.
Circular pair mating system
An outbreeding scheme in which each pair is mated only once. Cages are visualized in a circle, and each cage contains one breeding pair in the nth generation. Another ‘circular’ set of cages serves as the breeding nucleus for the n+1 generation. Each mated pair in the nth generation contributes one female and one male to the n+1 generation. Outbreeding is accomplished by assigning the female and male derived from each nth generation cage to different cages in the n+1 generation.
Swiss origin mice
Most outbred stocks are of ‘Swiss’ origin, derived from nine mice imported to the US in 1926. Although considered outbred, they have a high degree of homozygosity, exemplified by the fact that many Swiss mouse stocks are blind due to the homozygous recessive rd1 allele.
Why are many Swiss stocks blind?
Homozygous recessive rd1 allele
Diversity Outbred mouse
A hetergeneous stock derived from the same eight founder inbred strains of the Collaborative Cross.
Consomic
Also known a chromosome substitution strains.
Inbred mice that are congenic for entire chromosomes, and are useful for studying polygenic traits.
Conplastic
Inbred mice that are congenic for different mitochondrial genomes (mtDNA) contributed by other inbred strains, other subspecies, or other species of Mus.
Recombinant inbred
When two inbred strains are crossed, the F1 hybrids are genetically identical (with chromosomes of each chromosomal pair separately contributed by each parent strain) but maximally heterozygous
How do you perpetuate breeding of segregated inbred strains?
Brother-sister mating system for more than 20 generations with heterozygosity for the mutations forced by 1) backcrossing, 2) intercrossing, 3) crossing and intercrossing, 4) backcrossing and intercrossing.
How do you perpetuate breeding of a coisogenic inbred strain?
Perpetuate the mutation by 1) brother-sister mating within the strain of origin, 2) backcross or cross-intercross system with strain of origin as parent strain, 3) brother-sister mating with heterozygosity forced by back- or intercrosses, 4) brother-sister mating between homozygotes.
How do you perpetuate breeding of a congenic inbred strain?
Perpetuate the transferred mutation by 1)backcross or cross-intercross system with strain of origin as parent strain, 2) brother-sister mating with heterozygosity forced by back- or intercrosses, 3) brother-sister mating between homozygotes.
4) Brother-sister mating within strain of origin may be used after 10-12 generations of backcrossing with periodic backcrosses to background strain
Radiation mutagenesis
Radiation was one of the earlier methods for in vivo mutagenesis, but in vitro radiation of embryonic stem (ES) cells is also performed
Chemical mutagenesis
Involves in vivo treatment of male mice or in vitro treatment of ES cells with mutagenic chemicals such as ethylmethanesulphonate (EMS) or N-ethyl-N-nitrosurea (ENU), which induce point mutations in DNA.
Transgenic mouse
Technically any mouse in which foreign DNA has been integrated into its genome, regardless of method.
Commonly refers to mice that are genetically altered by additive transgenesis.
Additive transgenesis
Microinjection of foreign DNA into the pronucleus of a fertilized egg. Each ensuing embryo results in a genetically different “founder” mouse, since the transgene is integrated in random sites of the genome of each founder mouse.
Hemizygous
Since injected DNA is not homologous to the mouse genome and is not an allele, transgenic founder mice are hemizygous (rather than heterozygous) for the transgene until the mice carrying the transgene are bred into homozygosity for the transgene.