Allele Symbol: Tyrc-e
Name: extreme dilution
Alteration at locus: Spontaneous Mutation
Gene Symbol: Tyr
Alteration at locus: Spontaneous Mutation
ES Cell Line: Not applicable
In the homozygous state, this mutant allele results in a light sandy brown/beige coloration on the C57BL/6J background strain.
Characteristics of the Locus: The albino (Tyr) locus encodes the rate-limiting enzyme for pigmentation, which is TYROSINASSE. The absolute requirement for functional TYROSINASE to catalyze the formation of melanin pigment is illustrated by the phenotypes of mice that lack this locus as a result of deletion, for example mice heterozygous for two overlapping deletions, MMRRC:009964 and MMRRC:009965 in which the albino locus is absent. The mice also lack all melanin pigment. Vertebrates that lack normal tyrosinase are characterized by reduction or absence of pigmentation in the eyes and/or skin. If the reduction of pigmentation is severe, optic nerve development may be abnormal, resulting in blindness. Reduction of melanogenesis may result from failure of normal tyrosinase function caused by its abnormal interaction with other proteins, from defects in its regulatory region, from absence or defect of the structural gene. The series of natural mutations that affect availability of normal tyrosinase function includes mutants of this type. C57BL/6J-Tyrc-2J/Tyrc-2J, available at The Jackson Laboratory, lacks tyrosinase activity as a result of point mutation in the structural region of the gene; Acromelanic (MMRRC:000140) may have a similar defect. Extreme dilution (MMRRC:000141) seems to have nearly normal pigmentation in the eyes, but their hair pigmentation is a uniform gray. In dark-eyed-albino (MMRRC:000139) the eye pigmentation is somewhat reduced, but intense, while the hair is unpigmented. Chinchilla mice(MMRRC:000144) are very dark, nearly black. Two of the mutant alleles, chinchilla mottled (MMRRC:000145) and extreme dilution mottled (MMRRC:000142) result in chimerism of hair and eye pigmentation that has been attributed to a rearrangement of the DNA 5kb upstream of the tyrosinase locus. One of the genes that regulates the activity of TYROSINASE is MITF. And there are functional interactions between TYROSINASE and TYROSINASE-RELATED PROTEIN within the pigment cell.
Strain of Origin: Wild caught mouse, circa 1920 by JE Knight.
Strain genetic background: C57BL/6J
Strain Development: First observed in wild mice trapped by JE Knight; later studied by JA Detlefsen; see note in Festing's Inbred Strains of Mice: CE. Backcrossed to C57BL/6J at least 10 generations then bred to homozygosity and maintained by sibling mating.
Suggested Control Mice:
Donor: Dr. ML Lamoreux, Texas A&M University
Feed 9% fat mouse diet.
Coat color: Beige
MMRRC Breeding System: Sib mating
Overall Breeding Performance:
|Viability and Fertility:||Female||Male||Comments|
|Homozygotes are viable:||Yes||Yes|
|Homozygotes are fertile:||Yes||Yes|
|Heterozygotes are fertile:||Yes||Yes|
|Age Reproductive Decline:||Unknown||Unknown|
Average litter size: 6
Recommended wean age: 4 weeks
Limited quantities of breeder mice (recovered litter) are available from a cryoarchive; recovered litter usually available to ship in 3 to 4 months.
Fee/unit (US $)
|Litter||Recovered litter1; additional fees for any special requests.|
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 and based on the transfer success rate of the MMRRC facility) to transfer to at least two 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.