International Mammalian Genome Society

The 14th International Mouse Genome Conference (2000)

Table of Contents * Genes, Physical Mapping and Sequencing * Gene Identification * Bioinformatics * Common Resources * RIKEN Session * Functional Genomics * Complex Traits * Mutagenesis * Developmental Genetics and Differentiation * Verne Chapman Memorial Lecture I and II

B35. Characterization of Phenotypes and Genetic Mapping of a New Spontaneous Mutant Mouse Sims (Sexual Immaturity, Megaencephaly, Seizure)

Soo Kyung Koo¹, Soojung Jin¹, Jin-Sung Lee¹, Sue Cook², Wesley Beamer², Rod Bronson², Kenneth Johnson², Barbara Knowles², Muriel Davisson² and Bermseok Oh¹.
¹Division of Genetic Diseases, Department of Biomedical Sciences, National Institute of Health, 5 Nokbun-dong, Eunpyung-gu, Seoul, 122-701, South Korea
²The Jackson Laboratory, 600 Main St. ME 04609, USA

A new mutant mouse sims spontaneously arose in B6/129 F1 hybrid colony and is now maintained in inbred genetic background after backcrossing 6 times to C57BL/6J. The mutant mouse generally has a lower body weight than its littermate, noticeably at its weaning age and shivers its body. It presents seizure and the histological study reveals severe developmental retardation of the secondary sexual organs including seminal vesicle, coagulating gland, and prostate in male and uterus in female making in result, then sterile. Testosterone level was basal in the mutant mice implying the mal-induction of the sexual organs by the gonadotrophin at the puberty, though testis seems to be normal producing mature sperms. Examination of brain did not show any histological difference between the normal and the affected though it has a 30% bigger weight than its littermate. Another phenotype is seizure which occurs in both the homozygote and heterozygote though the severity is different between them. This phenotypic study suggests that a critical gene controlling the physiology of puberty process, probably in CNS, is disrupted in this mutant.

To map the chromosomal location of sims mutation, we used an inter-subspecies cross between CAST/Ei and heterozygous sims mouse. The results of linkage analysis from 750 F2 progenies are as follows; (1) the gene order is D18Mit88-Egr1-D18Mit12, D18Mit120-D18Mit135,D18Mit134, D18Mit71-D18Mit14-Fgf1-D18Mit17; (2) sims gene is positioned between Fgf1 and Egr1. There is no known mutant mouse matched for this phenotype at the region of chromosome and can be used as a new animal model for the study of seizure and hormonal imbalance during puberty.