Mouse chromosome 15

Frequent deletion in chromosome 4 and duplication of chromosome 15 in liver epithelial cells derived from long-term culture of C3H mouse hepatocytes

Prolonged culture of hepatocytes isolated from mouse liver results in the spontaneous development of colonies of liver epithelial cells that can proliferate indefinitely in vitro. We established 5 such cell lines from C3H/HeJ mice (C3H) and 22 cell lines from C3H/HeJ x C57BL/6J F1 mice (C3B6F1) to investigate whether any specific karyotype alterations may be associated with the development of such cells. These lines retained some properties of hepatocytes as well as showing bile-duct-cell characteristics, and comprised mainly near-diploid and/or hypotetraploid cells. Karyotypic analysis of the C3H cell lines indicated that most cells have loss of chromosome 4 or deletion involving the C7 portion, while at least 1 (for near-diploid cells) or 2 (for hypotetraploid cells) copies of chromosome 4 were usually intact. In addition, gain of an extra chromosome 15 was frequently observed in these cell lines. Analysis of the microsatellite DNA polymorphic markers in 22 C3B6F1 lines revealed that a majority of them showed loss of heterozygosity (LOH) for, at least, 1 of 3 polymorphic loci on chromosome 4, but not for 2 loci on chromosomes 7 and 11. Mouse chromosomes 4 and 15, therefore, may contain genes related to the ability of such liver epithelial cells to grow indefinitely in vitro [The locus on chromosome 4 was designated as liver-cell immortalization (LCI) locus].

A novel, conserved gene of the rat that is developmentally regulated in the testis

From a rat testis library three overlapping cDNA clones were isolated that represent a novel single-copy gene, designated Tegt. Two transcripts of 2.8 and 1.0 kb were found in each organ tested. The shorter transcript was highly abundant in adult testis. A similar expression pattern was found in the mouse. Analysis of rat RNA from different stages of spermatogenesis indicated that accumulation of the short transcript occurred mainly postmeiotically. The rat Tegt gene maps to Chromosome (Chr) 7, and its mouse homolog to Chr 15.