Biochemical markers in rats: linkage relationships of aconitase (Acon-1), aldehyde dehydrogenases (Ahd-2 and Ahd-c), alkaline phosphatase (Akp-1), and hydroxyacid oxidase (Hao-1)

A genetic linkage map of rat chromosome 5 reveals extensive linkage conservation with mouse chromosome 4

Linkages among three biochemical loci (Aco1, Ahd2, and Mup1) and four microsatellite loci (A8, Glut1, Jun, and Pnd) were determined to construct a linkage map of rat Chromosome (Chr) 5. Consequently, an extensive linkage map on rat Chr 5 was constructed with the following gene order: A8-Aco1-Mup1-Jun-Glut1-Ahd2-Pnd. In this linkage map, the Jun and A8 loci are newly placed, and two previously reported linkage groups on rat Chr 5 are connected by the Jun locus. The linkage map indicates an extensive linkage conservation between the loci on rat Chr 5 and those on mouse Chr 4.

The gene map of the Norway rat (Rattus norvegicus) and comparative mapping with mouse and man

The current status of the rat gene map is presented. Mapping information is now available for a total of 214 loci and the number of mapped genes is increasing steadily. The corresponding number of loci quoted at HGM10 was 128. Genes have been assigned to 20 of the 22 chromosomes in the rat. Some aspects of comparative mapping with mouse and man are also discussed. It was found that there is a good correlation between the morphological homologies detectable in rat and mouse chromosomes, on the one hand, and homology at the gene level on the other. For 10 rat synteny groups all the genes so far mapped are syntenic also in the mouse. For the remaining rat synteny groups it appears that the majority of the genes will be syntenic on specific (homologous) mouse chromosomes, with only a few genes dispersed to other members of the mouse karyotype. Furthermore, the data indicate that mouse chromosome 1 genetically corresponds to two rat chromosomes, viz., 9 and 13, equalizing the difference in chromosome number between the two species. Further mappings will show whether the genetic homology will prove to be as extensive as these preliminary results indicate. As might be expected from evolutionary considerations, rat synteny groups are much more dispersed in the human genome. It is clear, however, that many groups of genes have remained syntenic during the period since man and rat shared a common ancestor. One further point was noted. In two cases groups of genes were syntenic in the mouse but dispersed to two chromosomes in rat and man, whereas in a third case a group of genes was syntenic in the rat but dispersed to two chromosomes in mouse and man. This finding argues in favor of the notion that the original gene groups were on separate ancestral chromosomes, which have fused in one rodent species but remained separate in the other and in man.

Chromosome assignments of the genes for glucocorticoid receptor, myelin basic protein, leukocyte common antigen, and TRPM2 in the rat

We have utilized rat-mouse somatic cell hybrids to make chromosomal assignments for the glucocorticoid receptor (GR), myelin basic protein (MBP), leukocyte common antigen (LCA), and testosterone-repressed prostate message-2 (TRPM2) genes in the rat. The genes for GR and MBP both map on chromosome 18 of the rat, which corresponds to the mapping of both genes on chromosome 18 of the mouse. The gene for LCA maps on chromosome 13, which is where C4b-binding protein beta-chain (C4BPB), coagulation factor V (F5), and renin have previously been assigned. This linkage group appears to be homologous to a substantial portion of mouse chromosome 1 and human chromosome 1q. Finally, the TRPM2 gene has been assigned to rat chromosome 15.

Genetic variability in SHR (SHRSR), SHRSP and WKY strains

Genetic background for SHR (SHRSR) and SHRSP and WKY lines were screened by using biochemical genetic markers and class I major histocompatibility complex (RT1) typing. There were many kinds of SHR (SHRSR), SHRSP and WKY inbred lines. The genetic variabilities within SHR (SHRSR) or SHRSP strains were small, but those within WKY strains were not so small. When SHR lines were compared with WKY lines, the allele distribution in SHR lines was different from that in WKY lines at 3-13 loci. Three genetic markers, the Es-3b, Es-4a and PT1k, were identified as specific markers of SHR (SHRSR) and SHRSP. WKY/Izm, WKY/Hos, and WKY/Jim also carried the PT1k as well as SHR lines, but WKY/N and WKY/NCrj had the RT1l haplotype.

Linkage of neutrophil response to a mutagen gene (Nrm-1) to the agouti locus in the rat

The ACI or BDIV rats responded with decreased or increased neutrophil levels in blood after the N-methyl-N-nitrosourea (MNU) administration. The F1 hybrids had decreased neutrophil counts, and the BDIV x (BDIV x ACI)F1 backcross offspring showed two phenotypes. The sex of the rats and the neutrophil response to MNU assorted independently. The results indicated that the neutrophil response to MNU was regulated by autosomal gene Nrm-1 with two alleles. The Nrm-1d regulates the decrease and the Nrm-1i regulates the increase of neutrophils in blood after the MNU administration. The results were confirmed by the SKUMIX computer program. We found that the Nrm-1 gene was linked to the agouti locus (chi-square = 10.3, P less than 0.001). The map distance between two genes was 33 +/- 5 cM. The Nrm-1 gene thus resides on the linkage group IV of the rat.

Genetic polymorphism of tear proteins in the rat

Polymorphism of tear proteins was found by agarose gel electrophoresis among inbred strains of rats. The proteins (RTP-1) are inherited as a single autosomoal trait. The locus was designated Rtp-1 (rat tear protein-1) and it had two codominant alleles (Rtp-1a, Rtp-1b). Although we did not find any recombinant between the Rtp-1 and the Mup-1 loci among 67 backcross progeny, we found 3 strains with the recombinant type between them in 33 inbred strains tested. The results suggest that the Rtp-1 locus is very closely linked with the Mup-1 locus, which belongs to rat linkage group II. RTP-1 proteins strongly reacted with anti-MUP-1 A serum on agarose gel electrophoretograms.