Donna L. George

The Genes for Growth Hormone and Chorionic Somatomammotropin Are on the Long Arm of Human Chromosome 17 in Region q21-+ qter

SummaryWe used a cloned cDNA probe for human growth hormone and Southern blotting techniques to analyze DNA from a series of rodentxhuman somatic cell hybrids for the presence of growth hormone-related sequences. Our results provide evidence for the assignment of the genes for growth hormone and chorionic somatomammotropin as well as a growth hormone-like gene to human chromosome 17. Analysis of mousexhuman hybrid cells containing only part of the long arm of chromosome 17 enabled us to localize these genes to region 17q21→17qter.

Gene dose effect: intraband mapping of the LDH A locus using cells from four individuals with different interstitial deletions of 11p.

The quantitative expression of LDH A was studied in hemolysates from four patients with different but overlapping interstitial deletions of the short arm of chromosome 11. Deficiency of LDH A was demonstrated in one patient, and the LDH A locus has been assigned to that segment of 11p for which this patient alone was deficient, i.e., to band 11p12 (region 11p1203 leads to 11p1208).

Assignment of the human gene for muscle-type phosphofructokinase (PFKM) to chromosome 1 (region cen→q32) using somatic cell hybrids and monoclonal anti-M antibody

Human phosphofructokinase (PFK; EC 2.7.1.11) is under the control of three structural loci which encode muscle-type (M), liver-type (L), and platelet-type (P) subunits; human diploid fibroblasts and leukocytes express all three loci. In order to assign human PFKMlocus to a specific chromosome we have analyzed human × Chinese hamster somatic cell hybrids for the expression of human M subunits, using an anti-human M subunit-specific mouse monoclonal antibody. In 18 of 19 hybrids studied, the expression of the PFKMlocus segregated concordantly with the presence of chromosome 1 (discordancy rate 0.05) as indicated by chromosome and isozyme marker analysis. The discordancy rates for all the other chromosomes were 0.32 or greater, indicating that the PFKMlocus is on chromosome 1. For the regional mapping of PFKM,eight hybrids were studied that contained one of five distinct regions of chromosome 1. These results further localize the human PFKMlocus to region cen→q32 of chromosome 1.

Cloning of DNA from double minutes of Y1 mouse adrenocortical tumor cells: Evidence for gene amplification

We have isolated a metaphase chromosome fraction highly enriched in double minutes (dm) from a mouse adrenocortical tumor cell line (Y1-DM). We have cloned DNA from this dm-enriched fraction in the lambda vector Charon 4A, and have characterized two randomly chosen recombinant bacteriophage clones from this dm DNA library. When 32 P-labeled DNA from each recombinant was hybridized to Southern blots of restriction endonuclease-digested DNA from different mouse cell lines, large differences were seen in the intensity of the resulting autoradiographic images, depending on the source of the genomic DNA. A very strong signal was obtained with DNA from the Y1-DM cells and with DNA from a related Y1 subline that lacks dm but contains a marker chromosome bearing a large homogeneously staining region (HSR). Hybridization to DNA from parental inbred mice and from two unrelated mouse cell lines produced a significantly weaker signal than that obtained with DNA from the Y1 cells, but the DNA fragments from the sources were of similar size. Based on results from filter hybridization analysis, we estimate that sequences homologous to the cloned fragments are approximately 100- to 200-fold more abundant in the genome of the Y1-DM cells than in the parental mouse cells. The data are consistent with the hypothesis that dm and HSRs in these cells contain amplified genes.

Regional mapping of human genes for hexosaminidase B and diphtheria toxin sensitivity on chromosome 5 using mouse × human hybrid cells

Mouse 3T3 (TK−) cells were fused to human leukocytes containing a balanced translocation [ins(3;5) (q27;q13q15)] in which part of the long arm of a chromosome 5 has been inserted into the long arm of a chromosome 3. Two independent, primary hybrid clones (XVI-10C; XVI-18A) retained the deleted chromosome 5 [del(5) (q13q15)] translocation product and were informative for regional mapping on chromosome 5 of genes involved in expression of hexosaminidase B (HEXB) and diphtheria toxin sensitivity (DTS). Both XVI-10C and XVI-18A clones were sensitive to diphtheria toxin. Toxin-resistant derivatives of these clones (XVI-10C DTR; XVI-18A DTR) were analyzed for chromosome content and expression of Hex B activity, as were XVI-10C and XVI-18A cells which had not been exposed to diphtheria toxin. The results of this study provide evidence for localization ofDTS to region 5q15→5qter on the long arm of chromosome 5, and localization ofHEXB to region 5pter→5q13.

Regional Mapping of Human Genes for Phosphoglucomutase-1 on Chromosome 1 and β-Glucuronidase on Chromosome 7 Using Mouse × Human Hybrids

Two independent mouse-human somatic cell hybrid clones contained different, de novo chromosome rearrangements involving the short arm of human chromosome 1. One hybrid clone contained a translocation between human chromosomes 1 and 7; the other clone contained a rearrangement product between human chromosomes 1 and 14. Analysis of these clones for expression of genes previously assigned to chromosome 7 and to the short arm of chromosome 1 provided evidence for localization of PGM--1 in segment 1p22.1 leads to 1p31.1, AK--2, ENO--1 and UMPK in region 1pter leads to 1p31.1, and GUS in region 7 pter leads to 7q22. The results have been used to examine the relationship between cytologic and genetic map distances on the short arm of chromosome 1.