Mice with chromosomal aberrations

Strain Lists

Definition and Applications

The diploid chromosome number in standard laboratory mice (genus Mus) is 40: 19 autosomes and the X and Y sex chromosomes. Whereas the autosomes and the X Chromosome are telocentric (centromere at one end of the chromosome), the Y chromosome is acrocentric (centromere near one end of the chromosome), the small “p” arm carrying the sex-determining genes.

The Jackson Laboratory has a large number of strains with chromosomal aberrations:

  • Aneuploidies: deviations from the normal diploid number of chromosomes in somatic cells. Examples include Robertsonian chromosomes and trisomies (Robertsonian chromosomes are metacentric (bi-armed) chromosomes formed when two single-armed (acrocentric or telocentric) chromosomes join at the centromere. 
  • Insertion: the transfer of a chromosome segment into a different chromosome
  • Inversion: inversion of a DNA segment within a chromosome (segment sequence is reversed with respect to the rest of the chromosome).  
  • Reciprocal translocation: exchanges of DNA segments between chromosomes.  
  • Transposition: the transfer of a chromosome segment to a different place on the same chromosome or to a different chromosome. 
  • Trisomy: an extra copy of all or part of a chromosome

Most chromosomal aberrations are detectable cytologically. Rearrangements can be used as dominant markers for linkage studies and for marking tissues in chimera and transplantation experiments. Many chromosomal aberrations may be used in FISH gene mapping and meiotic nondisjunction studies. Reciprocal translocations produce either semi-sterility or complete male sterility. Other aberrations, especially homozygous deletions and whole chromosome trisomies, are lethal.

Because of the similarity between human and mouse reproductive systems, some chromosomal aberrations in the mouse are useful for modeling the effect of chromosomal aberrations on human fertility. Robertsonian chromosomes in combination can be used to produce whole chromosome trisomy for specific mouse chromosomes.

Strains with chromosomal aberrations at The Jackson Laboratory are maintained and distributed by The Cytogenetic and Down Syndrome Models Resource. They are primarily mouse models for Down syndrome.

Nomenclature

Chromosome aberrations are designated by a letter abbreviation identifying the type of aberration (see following chart), the number(s) of the chromosome(s) involved in parentheses, and a series symbol. The series symbol consists of the ILAR-assigned Laboratory Registration Code for either the person or laboratory that discovered or produced the aberration, preceded by a series number for either that investigator or laboratory. Symbols may be abbreviated by removing the parenthetical chromosome information.

In

Inversion (e.g., In(5)30Rk  in STOCK In(5)30Rk/J, Stock Number 000852)

Is

Insertion (e.g., Is(7;1) 40H (part of Chr 7 into Chr 1) in C3H/HeJ-pJ Is(7;1)40H/J, Stock Number 002460)

Rb

Robertsonian chromosomes (translocations) (e.g., Rb(6.16)24Lub (swap of pieces of 6 and 16 – 6 attaches to 16; 16 attaches to 6)) in STOCK Rb(6.16)24Lub, Stock Number 000885)

T Translocation

Tp

Transposition (e.g., Tp(Y)1Ct in B6-Aw-J-EdaTa-6J.Cg-Sxrb Hya-/J, Stock Number 001730) (segment of Y short arm transposed to distal long arm)

Ts

Trisomy (e.g., Ts(1716)65Dn in B6EiC3Sn a/A-Ts(1716)65Dn, Stock Number 001924) (Actually, this is only a partial trisomy because whereas a trisomy is three copies, this only has a piece of Chr 16 attached to Chr 17.)

Tips on Care and Handling

Many of the strains carrying chromosomal aberrations require special breeding schemes and handling. A particular strain may be maintained either as homozygous or segregating for an aberrant chromosome. To produce mice trisomic for a specific chromosome, different strains may need to be combined. Please consult with a technical support representative if you need more information about the care and handling of a specific strain.

Considerations for Choosing Controls

Often, studies involving chromosome aberrations do not require controls. The appropriate controls for segregating aberrations are wild-type littermates; those for homozygous aberrations maintained on standard inbred backgrounds are inbred strains of the same background (See Inbred Mice). Because of their origin from wild mice, Robertsonian chromosomes maintained homozygously and not on a standard inbred background do not have a genetically similar control.

For details on chromosomal aberration nomenclature, view our interactive tutorial on mouse nomenclature.