Strain Name:
Stock Number:
Citation ID:
Other Names:
Tk+/-, B6;129P2-Tk1tm1Vnd/Mmcd

Gene Information

Name: thymidine kinase 1; targeted mutation 1, Vasily N Dobrovolsky
Synonyms: Tk -
Type: Allele
Species: Mus musculus (mouse)
Chromosome: 11
Alteration at locus: Knockout
Name: thymidine kinase 1
Synonyms: Tk-1, D530002A18Rik
Type: Gene
Species: Mus musculus (mouse)
Chromosome: 11
Alteration at locus: Knockout
NCBI: 21877
Homologene: 37749
Genetic Alterations
One copy of the endogenous thymidine kinase gene was inactivated by replacing 1kb fragment containing the promoter, the first exon, the first intron and part of the second exon by a neo cassette. The resulting animals (heterozygous for the target gene) are sib mated to produce homozygotes.
Genotype Determination
ES Cell Line
E14TG2a derived from 129P2/OlaHsd
Homozygous: knockout animals can be produced by (heterozygous X homozygous knockout) parents. Homozygous knockout male and female animals have sclerosis of glomeruli, secretory changes in salivary glands. They are poor breeders and die by 6-7 months old.
Heterozygote: unremarkable.
Mammalian Phenotype Terms
Allelic Composition: Tk1tm1Vnd/Tk1tm1Vnd (Genetic Background: involves: 129P2/OlaHsd * C57BL/6 )

Allelic Composition: Tk1tm1Vnd/Tk1+ (Genetic Background: involves: 129P2/OlaHsd * C57BL/6 )

MeSH Terms
  • Animals
  • Antimetabolites/metabolism
  • Antimetabolites/pharmacology
  • Blotting, Southern
  • Cell Line
  • Cloning, Molecular
  • Drug Resistance/genetics
  • Embryo, Mammalian/cytology
  • Embryo, Mammalian/drug effects
  • Ethylnitrosourea/toxicity
  • Genetic Vectors
  • Mice
  • Mutagenicity Tests/methods
  • Mutagens/toxicity
  • Mutation
  • Polymerase Chain Reaction
  • Recombination, Genetic
  • Stem Cells/drug effects
  • Stem Cells/physiology
  • Thymidine Kinase/drug effects
  • Thymidine Kinase/genetics
  • Trifluridine/metabolism
  • Trifluridine/pharmacology
Strain Development
Original mutation was produced in 129 ES cells. Chimeras were backcrossed to C57BL/6 at least 4 times. Present genetic content is less then 10% 129 and more than 90% C57BL/6.
Suggested Control Mice
Wild-type littermates
  • In vivo mutation detection - Tk+/- animals are useful as a model for in vivo mutation detection in an endogenous autosomal gene. They are an in vivo analog of mouse lymphoma cells L5178YTk+/- widely used for mutation studies. Tk-/- (KO) animals can be used to determine biological significance of thymidine kinase deficiency and salvage pathway of nucleotide synthesis. Also they can be a model of kidney failure due to unidentified cause.
Vasily Dobrovolsky, Ph.D., National Center for Toxicological Research, United States Department of Agriculture.
Primary Reference
Dobrovolsky VN, Casciano DA, Heflich RH. Development of a novel mouse tk+/- embryonic stem cell line for use in mutagenicity studies. Environ Mol Mutagen. 1996;28(4):483-9. (Medline PMID: 8991081)

Colony and Husbandry Information

Cages should be inspected regularly for the presence of sick and dead Tk-/- animals.

Colony Surveillance Program and Current Health Reports

Mice recovered from a cryo-archive will have health surveillance performed on recipient females. Health reports will be provided prior to shipment. If you require additional health status information, please email .
Coat Color
Black, brown or agouti
MMRRC Breeding System
Sib mating
Breeding Scheme(s)
  • Tk+/- (heterozygous) females are mated with Tk+/- (heterozygous) males. (Tk+/+ offspring are discarded, Tk+/- offspring are retained for studies and the next round of maintenance of the colony, Tk-/- offspring are retained for studies.)
  • Heterozygote Female x Heterozygote Male
Overall Breeding Performance
Viability and Fertility: Female Male Comments
Homozygotes are viable: Reduced Reduced
Homozygotes are fertile: Reduced Reduced
Heterozygotes are fertile: Yes Yes
Age Reproductive Decline: Unknown Unknown
Average litter size
Recommended wean age
3 weeks

Order Request Information

Limited quantities of breeder mice (recovered litter) are available from a cryoarchive; recovered litter usually available to ship in 3 to 4 months.

Cryopreserved material may be available upon request, please inquire to for more information.

Distribution of this strain requires submission of the MMRRC Conditions of Use (COU). A link to the COU web form will be provided via email after an order has been placed; the form should be completed then or the email forwarded to your institutional official for completion.

Additional charges may apply for any special requests. Shipping costs are in addition to the basic distribution/resuscitation fees. Information on shipping costs and any additional charges will be provided by the supplying MMRRC facility.

Click button to Request this one strain. (Use the MMRRC Catalog Search to request more than one strain.)
MMRRC Item # Description Distribution Fee / Unit (US $) Units Notes
000014-UCD-RESUS Litter recovered from cryo-archive $3,033.00 / $6,017.01
Non-Profit / For-Profit
Litter Recovered litter1; additional fees for any special requests.
Cryopreserved material may be available upon request, please inquire to for more information.

1 The distribution fee covers the expense of resuscitating mice from the cryo-archive; you will receive the resulting litter. The litter will contain at minimum one mutant carrier; the actual number of animals and the gender and genotype ratios will vary. (Typically, multiple breeder pairs can be established from the recovered litter.) Prior to shipment, the MMRRC will provide information about the animals recovered. If you anticipate or find that you need to request specific genotypes, genders or quantities of mice in excess of what is likely from a resuscitated litter, you may discuss available options and pricing with the supplying MMRRC facility.

2 An aliquot is one straw or vial with sufficient sperm to recover at least one litter of mice, as per provided protocols, when performed at the MMRRC facility. The MMRRC makes no guarantee concerning the success of these procedures when performed outside the MMRRC facilities.

3 An aliquot contains a sufficient number of embryos (in one or more vials or straws and based on the transfer success rate of the MMRRC facility) to transfer into one to three recipients. The MMRRC makes no guarantee concerning embryo transfer success experienced in the recipient investigator's laboratory. Neither gender nor genotype ratios are guaranteed.

To request material from the MMRRC: Please fill out our on-line request form (accessible from the catalog search results page, or click the Request this Strain button in the fees section). If you have questions or need assistance completing this form, you may call Customer Service at (800) 910-2291 (in USA or Canada) or (530) 757-5710 (international calls). Before you call, please have with you: the MMRRC item number, quantity needed, Bill-to and Ship-to contact information.