Colony management scenarios and strategies following a pause or interruption (e.g. COVID-19 lockdown)

The following guidance outlines scenarios that may be encountered when re-starting breeding and animal experiments after a pause (e.g. re-starting work with mice after the COVID-19 lockdown). Different strategies are presented for each scenario to optimise the use of available animals and to minimise surplus animals when planning future breeding (e.g. via breeding, archiving or experimental strategies), considerations to inform selection of the most appropriate strategy and the limitations associated with each strategy are also presented. The scenarios were created with mice in mind, but many of the principles apply to other species. Refer to the Glossary for definitions of technical terms mentioned in the scenarios.

Colony management scenarios following a pause or interruption
Scenario 1 The colony will not be used for research for the next six months.
Scenario 2 Stock animal numbers were reduced due to pause/interruption but the colony now needs to be maintained with greater numbers, to allow for an increase in numbers for future experiments.
Scenario 3 Stock animal numbers were reduced due to pause/interruption but the colony now needs to be expanded to breed experimental cohorts immediately.
Scenario 4 Complex breeding is required (e.g. breeding conditional alleles, or other multi-allelic crosses) but not all required strains are available.
Scenario 5 Experimental cohorts are ready, but the resources (e.g. functional, calibrated equipment, consumables or trained and competent staff) are not available.
Scenario 6 The experiment was only partly completed prior to pause/interruption and the remaining part now needs to be completed.
Scenario 7 The strain needed for a new experiment is no longer available.
Scenario 8 Archiving was incomplete or not initiated but archiving of strain is still required.
Scenario 9 Rapid breeding of animals with specific characteristics (e.g. sex or age) is required.
Mouse repository index

 

 

Scenario 1 – The colony will not be used for research for the next six months.

Strategy

Considerations

Limitations/caveats

a) Archive the strain.

When will animals be required for experiments in the future? Six months is on the cusp of when archiving could be considered. In all cases beyond 12 months, archiving should be considered and the financial costs of archiving versus retaining holding stock compared.

 

Are sperm or embryos more appropriate to cryopreserve? Scenario 8 provides practical considerations for archiving a strain using sperm or embryo cryopreservation.

 

How complex is the strain? What genotype is needed for the experiment? What background is it on? Are there any fertility issues?

 

Are animals of appropriate genotype/age/sex available for cryopreservation?

Is the technical expertise available for immediate cryopreservation?

Rederivation of archived strains takes time and has associated costs (both animals used and financial). See Archiving Best Practice for estimated timelines for recovery of different genotypes and cryopreservation methods.

 

When archiving is outsourced or takes place at a repository, animals may have to undergo quarantine before becoming available for use in experiments.

b) Retain holding stock but do not breed.

What is the required number of holding stock for future breeding requirements? This will depend on the genotype. For example, to be able to breed ten homozygous animals of mixed sex, a holding stock of ten heterozygous females and five heterozygous males would be required.

 

 

 

 

What is the reproductive lifecycle of the colony (including strain-specific optimal breeding age)? If the optimal breeding age range is narrow, this strategy is unsuitable.

The length of time animals can be held without breeding depends on the optimum and maximum breeding ages for the strain in question, which should be known in advance. This reduces the risk of losing the strain and wasting animals. For example, C57BL/6N can usually be bred up to 16 – 18 weeks old.

 

Animals over six months old rarely give good breeding performance.

What is the age of current stock animals? Will keeping animals for six months risk developing welfare or fertility issues relating to older stock?

Older animals may require specific ethical approval for use in research.

 

Genetically altered (GA) strains may develop fertility and welfare issues with age.

c) Intermittent breeding.

Is the genetic complexity and breeding performance of the colony amenable to intermittent breeding (rather than constant mating)? Consider the background strain, the average litter size, the percentage of unproductive matings and the age at which matings are normally set up. Backcross colonies (both those that are congenic and those that are in the process of changing background and may not be congenic yet) can usually be held comfortably with intermittent breeding.

 

Intermittent breeding should be used instead of constant mating (where appropriate) to ensure that the number of animals needed for future experiments is always available by replacing breeding stock with the same number of their offspring from the colony once they reach an appropriate age (e.g. when the breeding performance is sufficient to rebreed the same number of animals). See the Worked example of intermittent breeding for an explanation of this strategy.

 

Closed colonies may require keeping a larger number of animals in the intermittent breeding colony, to avoid causing a genetic bottleneck and to reduce inbreeding depression.

 

If the number of animals needed for a future experimental breed is large, it may be necessary to breed in two steps, including a bulk-up step to increase the stock for the larger future breed. This would reduce the number of animals needed for the intermittent breed but would require a longer breed time when the cohort is needed.

d) Retain holding stock with constant mating.

What is the timeline for experiments in the pipeline? If it is certain that the colony will be required to produce animals for experiments in six months’ time, intermittent breeding should be used (where appropriate). Constant mating of animals will likely produce more animals than required, even once experiments begin, leading to wasted animals.

 

Can a subset of stock be kept constantly breeding and future breeding stock retained to enable a rapid increase in breeding capacity when required?

 

What is the required age of the breeding stock when it is time to breed for future experiments?

Constant mating is only recommended for colonies with known fertility issues.

 

There is the potential to waste animals if experimental plans change.

 

Animals over six months old rarely give good breeding performance.

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Scenario 2 – Stock animal numbers were reduced due to pause/interruption but the colony now needs to be maintained with greater numbers, to allow for an increase in numbers for future experiments.

Strategy

Considerations

Limitations/caveats

a) Backcross to expand an established congenic or co-isogenic colony.

Is the correct background strain available? Ensure that the background is kept consistent. Order in more background strain animals from a breeder if necessary.

 

How old are the animals and is it likely that they will breed successfully (consult relevant breeding records)?

If the correct background strain is unavailable, consider archiving the strain and waiting until they are available (see Archiving Best Practice).

 

Assisted reproductive techniques may be needed if the breeding stock is too old (see strategy (e) in this scenario).

b)  Backcross if the strain is mixed and/or in the process of being backcrossed.

 

What backcross is appropriate for the experiments?

 

Which allelic combinations are required at end of the backcross?

 

What is the current backcross status? SNP panels are available for a range of inbred strains to assess the purity of background strains.

 

How does the current backcross number compare with any previously used in the same programme of work? Future experiments may need to be adapted to account for differences in backcross number.

 

Could this genetic background be reproduced to perform similar experiments in the future?

 

Strategy (a) includes additional considerations about backcrossing.

Requires knowledge of the current backcross status.

 

SNP panels can be used to check backcross status of inbred strains, but they may not include the specific gene/alleles and variants important for the experiment.

 

Backcross should include a cross using female carriers to ensure the Y chromosome from the recipient (background) strain is introduced.

c) Restock from supplier.

Are stock available? Preferably from the same supplier originally used? On an identical background?

 

Has the current experimental stock drifted genetically from the original stock (this will happen over only two to three years)?

 

Are the necessary genotyping assays available?

 

Has the material transfer agreement (MTA) expired?

Check correct nomenclature to access the appropriate source of animals.

 

SNP panels can be used to verify strains, but they may not include the specific gene/alleles and variants important for the experiment.

d) Intercross.

Is this a closed colony? When there are few breeding individuals inbred depression can occur.

 

What is the reproductive lifecycle of each sex and the overall breeding performance for the strain?

 

What genotypes are available to refresh the strain? Ensure all necessary strains and genotypes will be available at an appropriate time for breeding.

 

If there are only a small number of animals available, consider how the background of the new colony resulting from intercrossing might be changed from what has previously been used (i.e. as a result of a genetic bottleneck). Future experiments may have to be adapted to account for this.

 

Consider restocking from the source or even outcrossing to a different wild type strain.

It is preferable to avoid developing substrains (via genetic drift) or inbred depression through long-term maintenance of closed colonies. For more information on genetic drift see Colony Management Best Practice: Genetic Drift.

e) IVF.

Is the relevant technical expertise available?

 

Is the relevant wild type strain available? For hybrid strains ensure the background strain most appropriate for future experiments is used.

 

Are there superovulation protocols available for this strain?

 

Is the superovulation efficiency of the strain sufficient?

 

Is the background amenable to IVF? Some strains do not superovulate efficiently (i.e. the oestrus cycle needs to be checked and natural embryos collected, which is inefficient). Some strains give low quality embryos.

 

Fresh sperm should be used when available.

 

If using cryopreserved sperm, were quality control assays performed?

 

Scenario 3 includes considerations when using IVF to breed cohorts for experiments.

Technical expertise is required.

 

Recipient mothers are required, which are not guaranteed to yield the required number of males and females or the required genotype.

 

If older females are the only animals available, this may not provide enough robust embryos to maintain the colony.

 

Maternal influences may impact future experiments if IVF has been used to restock a colony.

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Scenario 3 – Stock animal numbers were reduced due to pause/interruption but the colony now needs to be expanded to breed experimental cohorts immediately.

Strategy

Considerations

Limitations/caveats

a) Intercross of different strains for complex breeds.

What is the breeding performance of the strains involved?

 

Keep the sex and the genotype of the parents consistent with prior experimental cohorts.

 

Will the resulting animals be used for future colony maintenance as well as this experiment?

 

Will this generate enough animals to supply the experiment? If not, are smaller cohorts suitable?

 

If planning to breed in multiple cohorts, adjust the experimental design to account for this (e.g. use cohort as a blocking factor by treating each cohort as a separate block of the experiment). See Blocking a nuisance variable on the Experimental Design Assistant website and Scenario 6 for strategies using blocks to complete an experiment.

 

What are the controls?

 

What allelic combinations are required?

If using smaller cohorts/blocks the study may be underpowered. This could mean the study is less likely to identify a true effect, or that any effect seen is potentially exaggerated.

 

Experimental design is complex and requires statistical expertise, consulting a statistician is recommended.

b) Intercross for homozygous GA or for recessive alleles.

What is the breeding performance of the strains involved?

 

Where is the stock source for future breeding? Ensure offspring from intercross are retained for future breeding stock, as well as supplying the experimental cohort.

 

Will this generate enough animals to supply the experiment? If not, are smaller cohorts suitable? Or should an initial expansion cohort be generated (backcrossing)? This will take at least one extra generation (~ three months) but will produce larger cohorts (strategy (c) below).

 

If planning to breed in multiple cohorts, adjust the experimental design to account for this (e.g. use cohort as a blocking factor by treating each cohort as a separate block of the experiment). See Blocking a nuisance variable on the Experimental Design Assistant website and Scenario 6 for strategies using blocks to complete an experiment.

For recessive alleles the desired ratio of genotypes for the experiments may not be obtained.

 

If using smaller cohorts/blocks the study may be underpowered. This could mean the study is less likely to identify a true effect, or that any effect seen is potentially exaggerated.

 

Experimental design is complex and requires statistical expertise, consulting a statistician is recommended.

c) Backcross for heterozygous GA strain – see Scenario 2 for general considerations and limitations of backcrosses.

Can trio matings be used to increase efficiency? This may not be applicable for some strains – consult appropriate breeding records or request them from animal suppliers.

 

For trios and harems, separate the females before littering so lineages can be tracked.

Permission might be required from the animal facility as trio mating can rapidly generate offspring.

Using one male in multiple matings with several different wild-type females to increase offspring numbers more quickly.

 

Are genetically appropriate females available?

Aggression may occur towards males that are travelling between mating cages. The likelihood of this is reduced by exposing the females to bedding from the male the day before pairing. The animals should be monitored for aggression.

Is generation of multiple, smaller cohorts over a longer period more appropriate for the experiment? For example, for time-consuming procedures.

 

Multiple cohorts should be incorporated into the experimental design, for example using cohort as a blocking factor. See Blocking a nuisance variable on the Experimental Design Assistant website and Scenario 6 for strategies using blocks to complete an experiment.

The ratios of different genotypes required for the experiment may not be generated within each cohort.

 

Experimental design is complex and requires statistical expertise, consulting a statistician is recommended.

d) IVF - superovulation of a small number of females to achieve higher embryo yield.

 

This is not best practice to generate experimental cohorts, but if choosing this strategy please note the experimental design considerations and limitations.

Is the superovulation efficiency of the strain sufficient for the experimental timeline?

 

Can the strain be recovered from remaining stock if the experiment fails?

 

If planning to phenotype offspring from assisted reproductive techniques, adapting the experimental design can help account for the effects of embryonic culture and maternal influences from the foster mother.

 

If comparing mice derived from IVF to mice derived from natural matings, adapting the experimental design can help account for unintended differences. For example, are there extra measurements that could be included to indicate if results are being affected by maternal influences?

 

For additional practical considerations regarding using IVF to restock a colony see Scenario 2.

When directly using offspring of IVF in experiments, the impact of maternal influence may be greater than if IVF is being used to restock a colony.

 

Experimental design is complex and requires statistical expertise, consulting a statistician is recommended.

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Scenario 4 – Complex breeding is required (e.g. breeding conditional alleles, or other multi-allelic crosses) but not all required strains are available.

Strategy

Considerations

Limitations/caveats

Generate intermediate stock (animals with a subset of the required genetic alterations, not the final experimental stock).

Will the currently unavailable strains become available when required for mating with the intermediate stock?

 

What are the backgrounds of the intermediate stocks? Consider genotyping for common genetic contaminants (e.g. reporters, recombinases, or strain contamination).

 

Can the intermediate stock be maintained with intermittent breeding until the unavailable strain can be received? For example, a strain homozygous for a floxed allele needs to be maintained correctly (e.g. appropriate breeding to avoid genetic drift). See Scenario 1 for intermittent breeding considerations.

 

Can the intermediate strain be archived? Scenario 1 covers options when animals will not be used for a defined period.

 

If maintaining the intermediate stock, what is the risk of being unable to perform the final cross (e.g. is there potential for further interruption)? Is the risk of wasting animals used in intermediate crosses too high if the unavailable strain remains unavailable?

 

Can breeding plans be altered to get a more advanced intermediate stock from available strains?

SNP panels can be used to check strains, but they may not include the gene/alleles and variants important for the experiment.

 

See Scenario 1 for limitations of intermittent breeding and archiving.

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Scenario 5 – Experimental cohorts are ready, but the resources (e.g. functional, calibrated equipment, consumables or trained and competent staff) are not available.

Strategy

Considerations

Limitations/caveats

a) Delay the start of the experiment.

When will the required resources become available?

 

Can training and competency assessment be arranged for personnel?

 

Does the experimental model/strain have a time-sensitive phenotype (e.g. aging model, or model with progressive tumour)?

 

Delaying the experiment may mean the animals can no longer be used for the planned experiment, or that the experimental design may need to be modified to account for phenotypic changes in the cohort following delay. See Blocking a nuisance variable on the Experimental Design Assistant website and Scenario 6 for considerations when splitting an experiment into blocks.

Ensure that the actual severity level for animals will not exceed the limits approved by ethical review.

 

Delaying the experiment might have implications for existing funding (e.g. a date before which all funds must be used).

b) Modify the experimental design, e.g. change the outcome measure (potentially using different equipment).

Are the required resources and personnel available?

 

Is continuity with previous experiments or blocks of an experiment important? See Scenario 6 for continuing an experiment using blocks and using positive controls.

 

If changing the outcome measure, what would be a biologically relevant effect size for the new outcome measure?

 

Are there enough animals available to conduct an adequately powered experiment?

 

Could a different experiment answer the same question?

See Scenario 6 for some of the limitations of certain modifications in experimental design.

 

Experimental design is complex and requires statistical expertise. If altering the experimental design, consulting a statistician is recommended.

 

Ensure any procedural modifications are approved by ethical review.

c) Reschedule other planned experiments to make use of the available animals.

Are the required resources and personnel available?

 

Are other planned experiments dependent on the outcome of other currently incomplete experiments?

 

Is it important to maintain continuity with previous experiments or blocks of an experiment? See Scenario 6 for continuing an experiment using blocks and using positive controls.

 

Are there enough animals available to conduct an adequately powered experiment?

Ensure that it is appropriate to conduct a planned experiment and respect inter-dependency of experiments in a pipeline.

 

Experimental design is complex and requires statistical expertise. If altering the experimental design, consulting a statistician is recommended.

 

d) Carry out experiment using cooperative working with trained and competent staff from another research group.

Are the equipment/consumable resources available?

Ensure any changes in staff carrying out procedures are approved by ethical review.

 

The skills and competency of staff in the research group may not be maintained if the experiment is reliant on staff from other research groups.

e) Share available experimental cohort with other research groups.

Would transport of the animals be required (e.g. to another animal facility)?

 

Are the animal characteristics (e.g. genotype, background, phenotype) appropriate for the recipient research group?

When verifying characteristics note that SNP panels can be used to check strains, but they may not include the gene/alleles and variants important for the experiment.

f) Cull and bank tissues for ex vivo or in vitro experiments.

Are the equipment, consumables and trained/competent staff available?

 

If using these tissues as a modification to the experimental design, strategy (b) in this scenario covers considerations when modifying experimental design.

 

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Scenario 6 – The experiment was only partly completed prior to pause/interruption and the remaining part now needs to be completed.

Strategy

Considerations

Limitations/caveats

a) Treat the experiment as two blocks in order to complete it. See Blocking a nuisance variable on the Experimental Design Assistant website.

The experiment can be spilt into two blocks where the first block has already been completed.

 

It is strongly recommended that two or more treatment groups are present in both blocks of the design (ideally all treatment groups will be present in both blocks).

 

If equal numbers of controls and treated animals were used in the first part of the experiment, the second part of the experiment can be performed in the same way.

 

If the first part had uneven numbers of controls and treated animals, a block design can still be used but it may require more animals overall than originally planned. For example, if more control than treated animals were used in the first part, more control animals may need to be included in the second part to achieve the pre-planned power despite having uneven groups (and vice versa if more treated animals were used in the first part).

 

If more animals are being used in the second part than originally planned a new randomisation sequence to allocate animals to control and treatment groups will have to be created.

Experimental design is complex and requires statistical expertise. If altering the experimental design, consulting a statistician is recommended.

 

Altered experimental design may require more animals overall than originally planned, which is recommended in this case as it enables data from all animals to contribute to the results.

 

If variability is different between the two blocks of the experiment, this should be taken into account in the analysis. Consulting a statistician is recommended for this.

b) Adding a positive control (e.g. a known phenotype).

Has a positive control been used in the first part of the experiment? If so, including a positive control group in the remaining part of the experiment will help identify changes over time.

 

A positive control strain can be used to test the experimental set up in the second part of the experiment. Even if it was absent in the first part, results from the positive control strain can verify whether the set up is consistent with earlier experiments. For example, if equipment or procedure rooms have undergone a deep clean during COVID-19 lockdown, this may have altered the experimental set up.

 

To add a positive control absent from the first part of the experiment, include the positive control as another level of the factor of interest (i.e. as another treatment group) in the experimental design. For example, if comparing the effect of a drug on an animal, in addition to having a group of animals treated with the drug and another with the vehicle, there will be a third group of animals treated with a positive control drug.

 

If more animals are being used in the second part than originally planned a new randomisation sequence to allocate animals to the positive control and existing treatment groups will have to be created.

Experimental design is complex and requires statistical expertise. If altering the experimental design, consulting a statistician is recommended.

 

Responses from positive control animals can have different levels of variability to other experimental groups, especially if responses are significantly higher or lower in the positive control group. Many analyses assume variability is the same across the treatment groups. If the variability increases as the response increases, then the data can be log transformed prior to analysis to control the variability in the groups with higher responses. Consulting a statistician is recommended for this.

c) Conclude study at this point.

Can the parts of the study already completed be published as a stand-alone or pilot study? Be clear that the experiment was concluded early due to COVID-19 related interruption. Publish the original sample size calculation and explain the reduced number of experimental units/animals used.

 

Document what has been done in sufficient detail enabling the study to be continued. See ARRIVE guidelines 2.0 for a checklist of information to include when reporting animal research.

The smaller sample size is likely to reduce the power of the experiment. This could mean the study is less likely to identify a true effect, or that any effect seen is potentially exaggerated.

 

The results are likely to have greater uncertainty. Report effect sizes and confidence intervals rather than performing formal hypothesis tests (i.e. those that generate p-values).

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Scenario 7 – The strain needed for a new experiment is no longer available.

Strategy

Considerations

Limitations/caveats

a) Remake the strain.

Is it better to remake a strain, or re-import the strain? Remaking a strain, especially a complex one, is likely to take longer and be more expensive than re-importation.

 

Re-importing the strain may require a new material transfer agreement (MTA) if the existing one has expired.

 

Remaking a strain will be time consuming and the genetic alteration may not be precisely replicated. Factor in the validation time and costs (both financial and animal) to remake a strain, especially a complex one such as a conditional allele.

 

Remaking strains from embryonic stem cells is impractical unless the original strain is completely unavailable.

 

Include an outcome measure in the experimental design to allow comparison with previous research to estimate differences to the original strain (e.g. include an endpoint measurement with a known response from the original strain).

Genotyping via PCR can check for the specific genetic alteration but will not pick up issues with the background strain.

 

SNP panels can be used to check the background of strains, but they may not include the gene/alleles and variants important for the specific experiment.

 

This may require more animals than originally planned. Experimental design is complex and requires statistical expertise. If altering the experimental design, consulting a statistician is recommended.

 

b) Delay the start of the experiment to establish a new colony of the original strain.

 

Will the experiment be completed within an appropriate timeframe for funding availability and existing deadlines?

Can the strain be acquired from another researcher? Is this possible from an intellectual property perspective? Is the MTA still valid? Is the genetic background of the strain appropriate for the experiment?

 

Are there different breeding strategies to speed up breeding when animals become available? For example, using one male in sequential matings with several different wild type females to generate many heterozygotes which could then be intercrossed concurrently. Scenario 2 and Scenario 3 cover breeding strategies to increase stock.

 

Are there other strains waiting to be crossed to this strain? How will they be maintained, should they be kept as archived frozen stock?

 

c) Use an alternative strain.

Is the next best strain available on an appropriate genetic background? Would the caveats of using this strain outweigh the time savings? For example, use of a different Cre strain than originally planned may be appropriate when Cre is expressed in a useful tissue, but it would be necessary to validate Cre expression throughout the body.

 

Where the experiment requires multiple strains to be crossed together, using an alternative strain may mean that offspring from subsequent crosses are on a different genetic background to other strain(s) in other groups of the same experiment (e.g. if different strains are being compared, and creation of only a subset of animals requires the alternative strain). This can be controlled through breeding and careful experimental design. It is possible to perform experiments on mixed backgrounds if the mix is known, is consistent across control and treatment/GA animals and can be recapitulated in the future. This may require more than one control group, making the analysis more complicated. Consulting a statistician is recommended.

 

For help finding alternative strains see the Mouse Repository Index.

 

d) Consider alternative experimental approaches.

Are there existing tissue banks that could be accessed through a collaboration, or existing datasets that can be mined, including tissues and information from other model systems or humans?

 

If alternative strains exist in other labs, a Research Collaboration Agreement can be mutually beneficial.

Material transfer agreements can be time-consuming and unexpectedly complex, this should be investigated early in any discussions.

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Scenario 8 – Archiving was incomplete or not initiated but archiving of strain is still required.

Strategy

Considerations

Limitations/caveats

a) Sperm cryopreservation.

What is the reason for archiving the strain? (e.g. to stop maintaining the strain as a live colony, the strain is being maintained by tick-over breeding, safeguarding the strain, a new allele has been introduced into the colony).

 

Are the required number/age of males available? Sperm cryopreservation will likely only require two males, ideally 10 – 24 weeks of age.

 

Has genotyping been performed for sperm donors to confirm genotypes before cryopreservation?

 

Does the strain have a proven record of fertilisation?

 

Is the expertise available to quality control check cryopreserved sperm before the live colony is culled? See Archiving Best Practice: Table 1 for required quality control checks.

 

Are the technical capabilities available to perform IVF/to recover the strain/to perform quality control?

 

Is embryo cryopreservation more appropriate? See Archiving Best Practice for additional considerations for selecting an archiving method.

 

Does the genetic background need to be maintained? Embryo cryopreservation is the only method to preserve a strain that has a non-congenic or uncommon background.

Depending on the background and genetic alterations of the strain, sperm cryopreservation may not be appropriate and embryo cryopreservation is preferred (e.g. for a multi-allelic strain). See (b) in this scenario and Archiving Best Practice: Table 2.

 

If stocks permit, it may be advantageous to freeze homozygous embryos.

b) Embryo cryopreservation.

What is the reason for archiving the strain (e.g. to stop maintaining the strain as a live colony, the strain is being maintained by tick-over breeding, safeguarding the strain, a new allele has been introduced into the colony)?

 

Do a sufficient number of animals of the right age or sex need to be bred for cryopreservation?

 

Is the strain for archiving amenable to superovulation?

 

Are there enough females of the correct age for superovulation? Embryo cryopreservation typically requires between 10 – 20 females (three to six weeks of age) and one older male (>10 weeks of age) to generate sufficient embryos.

 

Have males and females from the strain been genotyped to confirm genotypes before cryopreservation?

 

Is the expertise available to quality control check cryopreserved embryos before the live colony is culled? See Archiving Best Practice: Table 1 for required quality control checks.

 

Is sperm cryopreservation more appropriate? See Archiving Best Practice for additional considerations for selecting an archiving method.

 

Is the genotype of the strain a simple heterozygote or wild type? If so, then sperm cryopreservation is recommended.

Depending on the background of the strain, the number of embryos produced per individual may be low (requiring more animals to yield sufficient embryos for cryopreservation), so sperm cryopreservation would be more efficient. See (a) in this scenario and Archiving Best Practice.

 

To slow genetic drift the strain should be refreshed by breeding to the wild type background. Sperm cryopreservation is recommended.

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Scenario 9 – Rapid breeding of animals with specific characteristics (e.g. sex or age) is required.

Strategy Considerations Limitations/caveats

Modify the experimental design to include additional factors to allow all animals generated to be used for the experiment.

 

For example, include sex as a factor to allow use of males and females in the second part of the experiment even though only males were used in the first part (i.e. a factorial design).

Using a wider range of ages or using both sexes may make a larger pool of animals available for the experiment.

 

Is age/sex a nuisance variable or potentially interesting? Nuisance variables are potentially another blocking factor, see Blocking a nuisance variable on the Experimental Design Assistant website and Scenario 6 for considerations when using blocking factors.

 

Was the sample size selected beforehand? If so, the sample size should be re-calculated.

Experimental design is complex and requires statistical expertise. If altering the experimental design, consulting a statistician is recommended.

 

Using both sexes or a wider age range may not be appropriate for the specific research question (i.e. if the process being studied is age-dependent, or only occurs in one sex).

 

Using one sex or a limited age range limits the conclusions that can be drawn from the research as they are valid over only the sex or age range used in the study. See Animal characteristics on the Experimental Design Assistant website for more information.

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Mouse repository index

Mouse repository

Address

Australian Phenome Bank 

Australian Phenome Bank (APB)

Building 117 Garran Road

The Australian National University, Acton ACT 0200 Australia

Animal Resources Centre 

Farm Road

Murdoch, Western Australia 6164 Australia

Center for Animal Resources and Development

Kumamoto University

2-2-1 Honjo

Kumamoto, 860-0811 Japan

Cornell Heart Lung Blood Resource for Optogenetic Mouse Signaling

Cornell University

T4002 VRT

618 Tower Road

Ithaca, NY 14853 USA

Canadian Mouse Mutant Repository 

25 Orde Street

Toronto, Ontario M5T 3H7 Canada

Charles River Laboratories 

251 Ballardvale Road

Wilmington, MA 01887 USA

Cystic Fibrosis Mouse Model Core 

Case Western Reserve University

2109 Adelbert Road

Cleveland, OH 44106-4948 USA

European Mouse Mutant Archive 

Helmholtz Zentrum München - German Research Center for Environmental Health, GmbH

Institute of Experimental Genetics

Ingolstädter Landstraße 1

Neuherberg / München, 85764 Germany

Dr. Elizabeth M. Simpson, Ph.D. 

Centre for Molecular Medicine and Therapeutics

University of British Columbia

950 West 28th Avenue

Vancouver, B.C. V5Z 4H4 Canada

European Mouse Mutant Cell Repository 

Helmholtz Zentrum München

Ingolstädter Landstraße 1

München, 85764 Germany

genOway

31 Rue Saint Jean de Dieu

Lyon, 69007 France 

GemPharmatech

12 Xuefu Road, Pukou High-Tech District

Nanjing, 210061 P.R. China

MRC Harwell 

Harwell Science and Innovation Campus

Oxfordshire, OX11 0RD UK

The Jackson Laboratory Mice and Services 

610 Main Street

Bar Harbor, ME 04609 USA

Korea Mouse Phenotyping Center 

520ho 81Dong

Seoul National University

Seoul, Republic of Korea

Mutant Mouse Resource & Research Centers 

Mouse Biology Program

2795 Second Street, Suite 400

Davis, CA 95618 USA

National Applied Research Laboratories

128 Academic Road Sec 2

Nankang, Taipei 11529 Taiwan, R.O.C.

National Cancer Institute at Frederick 

P.O. Box B, Thompson & Beasley Drive

Building 1021, Room 10

Frederick, MD 21702 USA

National Institute of Genetics 

Mammalian Genetics Laboratory

1111 Yata

Mishima, Shizuoka 411-8540 Japan

Oriental BioService, Inc

Minamiyamashiro Laboratory

181 Minamiyamashiro-mura

Souraku-gun, Kyoto 619-1401 Japan

Oak Ridge Collection at The Jackson Laboratory

The Jackson Laboratory

600 Main Street

Bar Harbor, ME 04609 USA

RIKEN BioResource Research Center

RIKEN BRC

3-1-1 Koyadai

Tsukuba, Ibaraki 305-0074 Japan

Shanghai Model Organisms Center, Inc

3rd Floor, Building 2, No 178 Banxia Road

Pudong New District, Shanghai 201318 P.R. China

Taconic Biosciences

One Hudson City Centre

Hudson, NY 12534 USA

Texas A&M Institute for Genomic Medicine

670 Raymond Stotzer Pkwy

4485 TAMU

College Station, TX 77843-4485 USA

University of North Carolina, Chapel Hill - Systems Genetics Core

120 Mason Farm Road

5047 Genetic Medicine Building, CB #7264

University of North Carolina,

Chapel Hill

Chapel Hill, NC 27599-7264 USA

Vanderbilt Cryopreserved Mouse Repository

2213 Garland Avenue

9410 MRB IV

Nashville, TN 37232-0494 USA Email Repository

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