Download MAX-BAX - Charles River Laboratories

Technical Sheet
Marker-Assisted Accelerated
Backcrossing (MAX-BAX®)
Time is of the essence when creating research models, and
marker-assisted accelerated backcrossing has proven valuable in
expediting the process of creating congenic strains. Charles River,
the industry leader in rodent research models, offers MAX-BAX®
for the directed selection of individuals/breeders with a preferred
genetic background. By backcrossing selectively rather than
randomly, you can significantly decrease the number of backcross
generations needed to produce a congenic strain, thereby
producing a research model faster, while simultaneously reducing
your facility, equipment and personnel costs.
MAX-BAX® Technology
Congenic strains are widely used in biomedical research
because they reduce genetic variability and provide insight into
the contribution of genetic background to phenotype. Congenic
strains are identical at all genetic loci except for one; that differing
locus is usually the transgene or knockout region of interest.
Utilizing traditional, random backcrossing methods, it takes 10
generations (upwards of 2.5 years) to produce a congenic strain.
Selectively breeding individuals containing more of the recipient
genome from each generation allows for accelerated congenic
strain production (Table 1).Those animals carrying the locus of
interest with the highest percentage of recipient versus donor
strain DNA are preferentially bred.
Genetic markers mapped to specific locations on each
chromosome are used to evaluate strain-specific genomic
polymorphism. Our mouse single nucleotide polymorphism (SNP)
panel, composed of 384 carefully selected SNP markers, was
designed to maximize polymorphism between common inbred
strains and provide even coverage of the mouse genome. Markers
are spaced at approximately 7 Mbp intervals, and about half of
the markers will be polymorphic between any inbred or outbred
strains, allowing the same panel to be used for any donor and
recipient strains.
The testing for the 384 SNP marker panel is performed on a
microarray platform using robust fluorescence-based SNP
genotyping assays (Figure 1). Results yield a defined analysis
of the genome in question, and a preferred breeding rank is
determined for all test individuals. The entire genome is analyzed
at each generation, which may make unexpected genetic
variation or breeding errors easier to detect.
The 384 mouse SNP panel complements our other mouse and
rat genetic background panels for inbred and outbred lines.
These include our 32 marker SNP panels for routine genetic
quality control and custom microsatellite panels for speed
congenics, mapping, fine mapping, and substrain or background
strain characterization.
TABLE 1. Congenic Strain Production Strategies
Traditional Backcross
Speed Backcross
Generation
Recipient Genome
Generation
Recipient Genome
F1
50.00%
F1
50.00%
N2
75.00%
N2
~80.00%
N3
87.50%
N3
~94.00%
N4
93.75%
N4
~99.00%
N5
96.88%
N5
~100.00%
N6
98.44%
N7
99.22%
N8
99.61%
N9
99.81%
N10
99.90%
[email protected]
www.criver.com
© 2013, Charles River Laboratories International, Inc.
technical sheet
Figure
1. SNP
Genotyping
Data forData
2 Markers
FIGURE
1. SNP
Genotyping
for 2
SNP rs13476621
Chromosome 2, 87.19 Mb
Markers
2. Two to three animals having the highest percentage of
recipient strain contribution, as determined by MAX-BAX®
analysis, should be mated to recipient strain animals The
Figure 1 showsaim
the fluorescence
is to produce about 10 heterozygotes for subsequent
data for 2 SNP markers. Each
point represents
the genotype of strain assessment. These animals will be
background
one animal for that marker. Blue
and red pointsdesignated
are animals that the N2 generation.
SNP rs13480740
Chromosome 10, 103.52 Mb
FAM Intensity
FAM Intensity
8699
10135
6862
7939
5025
5742
3189
3546
are homozygous for one of the two
possible alleles, while green points
3. thatThis
process of
are animals
are heterozygous
for selected breeding will be repeated at
both possible alleles. Each animal
each
generation
typically to N5, at which point congenic
is assayed for 384
markers,
and its
genetic profile is compared to that of
individuals
should be obtained.
the recipient strain
to identify animals
with the highest amount of the desired
background.
4. The time frame, assuming no problems with breeding
or health, etc., will be approximately 98 days per
generation or 490 days to complete the project (1.3 years)
Figure
1. shows the fluorescence data for 2 SNP markers.
The testing for the 384 SNP marker panel is performed
2. Two to three animals havingConventional
the highest percentage
backcrossing takes upwards of 2.5 years to
Each
point represents
therobust
genotype
of one animal for of
that
on a microarray
platform using
fluorescence-based
recipient strain contribution, as determined by
produce
the
desired
congenic strain.
SNP genotyping
assays
1). are
Results
yield a that
defined
MAX-BAX® analysis, should be mated to recipient strain
marker.
Blue and
red(Figure
points
animals
are homozygous
analysis of the genome in question, and a preferred
animals The aim is to produce about 10 heterozygotes
for
one of
the
two possible
while green points are
breeding
rank
is determined
for allalleles,
test individuals.
for subsequent background strain assessment. These
Test Results
and Sample Submission
The entire that
genome
analyzed at eachfor
generation,
animals
the N2 generation.
animals
areisheterozygous
both possible alleles.
Eachwill be designated
®
Results
from
MAX-BAX
analysis are typically reported in one
which may make unexpected genetic variation or
animal is assayed for 384 markers, and its genetic profile
is
3. This process of selected breeding will be repeated
breeding errors easier to detect.
week.
Tail
snips
should
be
collected and immersed in 70% ethanol
compared to that of the recipient strain to identify animals
at each generation typically to N5, at which point
and
refrigerated
(4°C)
prior
to shipment. Other tissues, such as ear
The
384
mouse
SNP
panel
complements
our
other
mouse
congenic
individuals
should
be
obtained.
with the highest amount of the desired background.
and rat genetic background panels for inbred and outbred
punches or toe clips may also be used. Please contact Charles
4. The time frame, assuming no problems with breeding
lines.
include
32 marker SNPindividual
panels for routine
As
theThese
animals
areourbackcrossed,
loci, and eventually
Laboratories
priorper
to shipment.
or health, etc., will River
be approximately
98 days
genetic quality control and custom microsatellite panels
entire
chromosomes,
will become
fixed and
for the recipient allele
and or 490 days to complete the project
generation
for speed
congenics, mapping,
fine mapping,
(1.3 years)
backcrossing takes upwards
substrain
background
strain characterization.
no
longerorrequire
monitoring.
This allows us to custom design
a Conventional
Please contact Charles River when planning your MAX-BAX®
of 2.5 years to produce the desired congenic strain.
panel for every
subsequent
backcross
generation,
saving
both
program or with other questions regarding our genetic testing
MAX-BAX® General Principles
Test Results and
Sample
Submission
time and money in the process.
services
of knockout
and transgenic rodents.
2239
3401
4564
5726
6888
8050
921
2208
2953
3698
VIN Intensity
4443
5188
5933
6678
VIN Intensity
While the absolute parameters of every MAX-BAX® project
are unique, we have listed some general principles that
® a road map to plan
can be used as
MAX-BAX
General Principles
a MAX-BAX® program.
®
Results from MAX-BAX® analysis are typically reported in
one week. Tail snips should be collected and immersed in
70% ethanol and refrigerated (4°C) prior to shipment. Other
While the absolute parameters of every MAX-BAX project
are such as ear punches or toe clips may also be used.
tissues,
contact Charles River Laboratories prior
1. If the initial
are already
a defined
background,
unique,
we animals
have listed
someongeneral
principles
that canPlease
be used
to shipment.
the F1 progeny (of the founder animal and
® a mate of the
asrecipient
a road strain)
map to
plan a MAX-BAX program.
will all be 50% recipient strain, so there is
Please contact Charles River when planning
no advantage in performing genetic analysis at this point
1. If the initial animals are already on a defined background,
your MAX-BAX® program or with other questions
If the founder animal is homozygous for the gene of
regarding
the
F1
progeny
(of
the
founder
animal
and
a
mate
of the our genetic testing services of knockout
interest, the progeny are obligate heterozygotes, and
transgenic rodents.
genotyping
for thestrain)
gene ofwill
interest
also not
necessary
recipient
all beis 50%
recipient
strain, soand
there
for this generation. If the initial animals are on a hybrid
is
no
advantage
in
performing
genetic
analysis
at
this
background, and the desired recipient strain is one of the
®
strain point
contributing
this background,
MAX-BAX
If thetofounder
animal is
homozygous
for the gene
genotyping of the F1 generation can identify animals with
of interest, the progeny are obligate heterozygotes, and
a higher-than average percentage of the recipient strain.
genotyping for the gene of interest is also not necessary
for this generation. If the initial animals are on a hybrid
background, and the desired recipient strain is one of
the strain contributing to this background, MAX-BAX®
genotyping of the F1 generation can identify animals with a
higher-than average percentage of the recipient strain.
[email protected]
www.criver.com
© 2011, Charles River Laboratories International, Inc.
[email protected]
www.criver.com
© 2013, Charles River Laboratories International, Inc.