Jumbled spine and ribs (Jsr): a new mutation on mouse Chromosome 5
Hiroyuki Miyoshi, Yasuhiro Kon, Kwang-Won Seo, Hee-Kyung Jin, Ai Hasegawa, Tomomasa Watanabe
Laboratory of Experimental Animal Science, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060-0818, Japan
Received: 1 June 1998 / Accepted: 15 October 1998
Abstract. Jumbled spine and ribs (Jsr) is an autosomal dominant
mutation that results in malformation of the axial skeleton. The
vertebrae of mutant mice (Jsr/+) are all shorter than those of nor-
mal mice (+/+) in the inbred line and show various abnormalities.
In addition, several ribs are fused at their proximal region because
of fusion of thoracic vertebrae. In this study, we localized the Jsr
mutation on distal Chromosome (Chr) 5 and constructed a high-
resolution map. Chromosomal mapping was performed with an
inter-subspecific backcross of (CKH-Jsr/+ × MOG) F
the Jsr allele and CKH-+/+. The predicted gene order around Jsr
was determined to be cen–(Epo, Pdgfa, D5Mit31, D5Mit374)–(Jsr,
Nfe2u, D5Mit99, D5Mit247, D5Mit284, D5Mit292, D5Mit327)–
D5Mit328–tel. Subsequently, high-resolution mapping concluded
the Jsr localization to be cen–Nfe2u–1.0cM–Jsr–0.2cM–
D5Mit247,292–tel. Jsr/Jsr homozygotes are alive, as the mutation
is not lethal. Based on histological analysis of mutant embryos, Jsr
is hypothesized to be caused by abnormal development of primor-
dial cells in the axial skeleton.
Abnormalities of vertebral development have often been observed
in humans as well as in many other animals. Numerous mutations
underlying such abnormalities in mice have been identified. One
combination of vertebral malformations and rib fusions is known
as “Vertebra-Rib Syndrome” (Theiler 1968). At least seven dis-
turbed somite formations caused by different genes have been
identified in mice: crooked tail (Morgan 1954), fused (Theiler and
Gluecksohn-Waelsch 1956), rib fusions (Theiler and Stevens
1960; Mackensen and Stevens 1960), pudgy (Gruneberg 1961),
rachiterata (Theiler et al. 1974; Varnum and Stevens 1974), mal-
formed vertebrae (Theiler et al. 1975), and rib-vertebrae (Theiler
and Varnum 1985). Vertebral development, beginning with somite
formation, is associated with the expression of many genes. Re-
cently, gene targeting studies have revealed that several transcrip-
tion factors play important roles in vertebral development. For
example, in null mutant mice with paraxis, a basic helix-loop-helix
transcription factor results in vertebral malformation and rib fusion
(Burgess et al. 1996). The null embryos of Mfh1, encoding a
winged helix/forkhead domain transcription factor, have also
shown vertebral column defects (Winnier et al. 1997).
The jumbled spine and ribs (Jsr) mutation in mice, producing
a short trunk and kinky tail, originated spontaneously in a cataract-
bearing mouse strain (CTA/Idr) at the Institute for Developmental
Research in Aichi, Japan. This mutation is also considered to be a
typical symptom of Vertebra-Rib Syndrome. In the present study,
to examine whether Jsr mutation is related to already known genes
or phenotypes, we tried to determine the basic mode of inheritance
and to perform chromosomal and high-resolution mapping. We
have also described herein the morphological differences between
normal and mutant mice, and the abnormal development of verte-
bral segments derived from the sclerotomal population in the em-
Materials and methods
Mouse strains and crosses for chromosome mapping study.
CKH strain carrying the Jsr mutation is maintained as an inbred strain in
our laboratory. The maintenance is usually done by sib mating between
mutant (Jsr/+) and normal (+/+) mice. The MOG strain derived from
Japanese wild mice (Mus m. molossinus) is also maintained as an inbred
strain in our laboratory. Intersubspecific backcross progeny were generated
by mating (CKH-Jsr/+ × MOG) F
carrying the Jsr allele to CKH-+/+ mice
to determine the chromosomal map.
Southern blot analyses.
Restriction enzyme length variation (RFLV)
analyses were performed for the loci of alpha-feto protein (Afp), beta-
glucuronidase (Gus), platelet-derived growth factor A-chain (Pdgfa), cau-
dal type homeo box-2 (Cdx2) and myocyte nuclear factor (Mnf); their
variations between CKH-Jsr and MOG were detected with PvuII, PstI,
SacI, DraI, and BamHI digestion, respectively. Southern blot analyses
(Southern 1975) were performed by the modified procedures described
previously (Watanabe et al. 1989).
Simple sequence length variations (SSVs).
PCR amplifications were
performed to detect variations for erythropoietin (Epo), nuclear factor ery-
throid-derived 2 ubiquitous (Nfe2u), and 16 microsatellite markers. Primers
for microsatellite markers D5Mit29, D5Mit31, D5Mit33, D5Mit51,
D5Mit60, D5Mit99, D5Mit101, D5Mit142, D5Mit247, D5Mit284,
D5Mit292, D5Mit327, D5Mit328, D5Mit374, D5Mit375, and D5Mit376
were purchased from Research Genetics (Huntsville, Ala. USA) and used
as recommended (Dietrich et al. 1992). Primers for Epo were synthesized
in this study according to a reference (Maichele and Chamberlain 1994).
Nfe2u primers in the 3Ј untranslated region were synthesized on the basis
of the cDNA sequence (Igarashi et al. 1995). They were 5Ј-
CAACAGCCTTCC-TCAGTCTTTC and 5Ј-ACAAAAGCAGTCACG-
GCAACAT, expected to give a product of 721 bp. The variations were
detected on 2% agarose gel electrophoresis for Nfe2u, and 3% Nusieve
agarose (FMC, Rockland, Me., USA) gel electrophoresis for Epo and mi-
Skeletons of adult CKH-Jsr mice and the em-Correspondence to: T. Watanabe
Table 1. Segregation from the crosses in the inbred CKH strain carrying Jsr mutation
and the reproductive characters.
litter sizeDam Sire Normal Mutant Total
(Jsr/+) 39 42 81 10 8.1
(+/+) 47 41 88 11 8.0
76 11 6.9
D5Mit99 genotype was examined in 3 of 19 progeny showing a normal phenotype
and 19 of 57 showing a mutant phenotype.
Mammalian Genome 10, 213–217 (1999).
© Springer-Verlag New York Inc. 1999