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Linkage map of the short arm of human chromosome 11: location of the genes for catalase, calcitonin, and insulin-like growth factor II.

The following order of genes on the short arm of human chromosome 11 (11p) was determined previously: parathyroid hormone (PTH)-the beta-globin gene cluster (HBBC)-HRAS1/insulin. Although it is generally agreed that HRAS1 (formerly termed c-Ha-ras-1) and the insulin gene are close to each other [1-4 centimorgans (cM)], their order on chromosome 11p is still in question. We have now added three other genes, those for catalase, calcitonin, and insulin-like growth factor II (IGF-II), to this map of chromosome 11p by use of restriction site polymorphisms adjacent to these genes in classical linkage analysis. Most importantly, we find no evidence of linkage between the catalase and HBBC loci. In addition, our data indicate that the calcitonin gene is located between the catalase gene and the PTH gene. Our best estimate of the distance between the catalase and calcitonin gene is approximately 16 cM, while that between the calcitonin and PTH genes is approximately equal to 8 cM. In agreement, very loose linkage was found between the catalase and PTH loci (approximately 26 cM). Since the catalase locus has been mapped to 11p13, these data support the view that the PTH, HBBC, HRAS1, and insulin loci are located on the distal short arm of chromosome 11. The IGF-II gene is tightly linked to both the HRAS1 oncogene and the insulin gene since no recombinants were observed between the IGF-II and the HRAS1/insulin loci. Thus, based on our linkage analysis we propose that the most likely gene order for the short arm of chromosome 11 is centromere-catalase-calcitonin-PTH-HBBC-HRAS1/insulin-tel ome re and that the IGF-II gene is very close to both the HRAS1 and the insulin genes.

Calcitonin↗

A linkage map of the mouse immunoglobulin lambda light chain locus.

The mouse immunoglobulin lambda light chain locus has been linked using field inversion gel electrophoresis. The lambda light chain locus classically contains two V and four J-C gene segments in inbred mouse strains, and was physically mapped in the BALB/c cell line Wehi-3 which contains unrearranged lambda light chain gene segments. The locus is relatively small and spans 300 kb, as defined by a variety of single and double digests using methylation-sensitive restriction enzymes. The order of the lambda gene segments is V2-J2C2J4C4-V1-J3C3J1C1, as was originally proposed. No evidence for nonmethylated CpG rich areas (HTF islands) within the region was found. Fine mapping using the lambda 1, lambda 3 rearranged cell line J558 mapped the gap between the V and J-C gene segments in the lambda 1 gene cluster (V1-J3C3J1C1) to approximately 70 kb. The similar distance (60-100 kb) found in the lambda 2 gene cluster (V2-J2C2J4C4) is further evidence that duplication of an ancestral locus occurred.

Animals↗

Conservation of human chromosome 18 in baboons (Papio hamadryas): a linkage map of eight human microsatellites.

A panel of 25 microsatellite loci known to map to human chromosome 18 was screened for length polymorphisms in a multigenerational pedigree of baboons (Papio hamadryas). Eight of these loci were polymorphic in the baboon pedigrees, with observed heterozygosity values ranging from 0.16 to 0.88. All eight loci show strong evidence of linkage. The most likely map order among the microsatellite loci for Papio is completely compatible with the locus order found in the human genome, and sex differences in recombination rates are also similar in the two species. We conclude that the organization of the chromosomal region defined by these loci is largely conserved between baboons and humans.

Animals↗

A multipoint genetic linkage map of mouse chromosome 18.

We have mapped 13 loci on mouse Chromosome 18 by Southern blot analysis of restriction fragment length polymorphisms among progeny from an interspecific backcross: (C57BL/6J X Mus spretus) X M. spretus. Complete haplotype analysis of 136 of these progeny was used to establish gene order and estimate genetic distances between loci. The gene order (from centromere to telomere) and recombination distances (in centimorgans) were as follows: PGK-1rs5-4.3-Tpi-10-11.8-(Egr-1, Hmg17-rs9)-2.1-Fgfa-2.2-Grl-1-10.1-(Cdx-1, Csfmr, Pdgfrb, Pdea, Rps14)-2.1-Adrb-2-22.9-Mbp. Pgk-1rs5, Tpi-10, Hmg17-rs9, and Rps14 had not been previously mapped in the mouse; Egr-1 had only been syntenically assigned to mouse Chr 18. Nine of the loci, spanning 18 cM, have homologs on the distal long arm of human Chr5--a region rich in genes encoding growth factors and receptors. An additional previously unmapped gene, Drd-1, predicted to be on mouse Chr 18 based on its human chromosomal location, was mapped to the middle region of mouse Chr 13.

Animals↗

Linkage mapping of a mouse gene, iv, that controls left-right asymmetry of the heart and viscera.

Inherited single gene defects have been identified in both humans and mice that lead to loss of developmental control over the left-right asymmetry of the heart and viscera. In mice the recessively inherited mutation iv leads to such apparent loss of control over situs: 50% of iv/iv mice exhibit situs inversus and 50% exhibit normal situs. The affected gene product has not been identified in these animals. To study the normal function of iv, we have taken an approach directed to the gene itself. As a first step, we have mapped iv genetically, by examining its segregation in backcrosses with respect to markers defined by restriction fragment length polymorphisms. The iv locus lies 3 centimorgans (cM) from the immunoglobulin heavy-chain constant-region gene complex (Igh-C) on chromosome 12. A multilocus map of the region suggests the gene order centromere-Aat (alpha 1-antitrypsin gene complex)-(11 cM)-iv-(3 cM)-Igh-C-(1 cM)-Igh-V (immunoglobulin heavy-chain variable-region gene complex).

Animals↗

Contribution to the physically anchored linkage map of the pig.

Thirty-three microsatellites have been mapped on the PiGMaP porcine genetic map. By comparison with the previously published PiGMaP maps, the maps of chromosome 2 (140 cM/70 cM) and chromosome 3 (180 cM/110 cM) were extended and new markers were mapped on the p-arm extremity of chromosome 7 and on the centromeric extremity of chromosome 15. New orders are proposed for markers on chromosomes 3 and 17. Six microsatellites isolated from cosmids were also localized on the cytogenetic map by fluorescent in situ hybridization. We tested the subcloning ligation mixture-polymerase chain reaction (SLiM-PCR) method for isolating microsatellites from cosmids. Subcloning is more effective when the cosmid harbours several microsatellites whereas SLiM-PCR is more straightforward when the cosmid contains a single microsatellite. Fifteen anonymous microsatellites were regionally assigned by using a hybrid cell panel. For map integration, the determination of a regional assignment of anonymous microsatellites by using a hybrid cell panel offers an alternative to microsatellite isolation from cosmids and their localizations by in situ hybridization.

Animals↗

Linkage mapping of the Fos cellular oncogene (Fos) to rat chromosome 6 and its possible role in the regulation of compensatory renal growth.

Using the analysis of HXB/BXH recombinant inbred (RI) strains, we have recently detected a suggestive association between the D6Mit9 marker and a compensatory growth of the remnant kidney after unilateral nephrectomy (P = 6 x 10(-)4). Based on conserved synteny between mice, rats, and humans, the putative quantitative trait locus (QTL) might map to a region with several positional candidate genes: for instance, the Fos oncogene was implicated as a possible candidate gene for compensatory renal growth (CRG). In the current study, we mapped the Fos gene in RI strains 27 cM apart from the position where the putative CRG regulatory QTL was detected. Despite relatively wide confidence intervals for mapping QTLs with modest effects in a small population of RI strains, this finding probably excludes the Fos as a positional candidate for CRG.

Animals↗