Genetic variation of an acid phosphatase (Acp-2) in the laboratory rat: possible homology with mouse AP-1 and human ACP2

Linkage Mapping of the Locus Responsible for Male Pseudohermaphroditism (mp) on Rat Chromosome 7

TF is a mutant rat strain showing male pseudohermaphroditism controlled by an autosomal single recessive gene (mp). The affected rats show lack of Leydig cells and androgen deficiency. In this study, we performed linkage analysis using F(2) progeny of crosses between TF and BN strains to determine the chromosomal localization of the mp locus. The mp locus was mapped in a 4 cM region of the distal region of rat chromosome 7 between D7Rat3 and D7Rat115 or D7Rat94. Comparison of the linkage map with corresponding regions of the published rat genome sequence revealed several candidate genes for the mp mutation, including the Dhh, Tegt, Gdp3, and Amhr2 genes.

A restriction fragment length polymorphism (RFLP) locus of rat (Rattus norvegicus) linked to the Cs-1 locus of rat linkage group XIII

A novel restriction fragment length polymorphism (RFLP) in inbred rats was revealed by Southern blot analysis with a clone arbitrarily chosen from a rat genomic library as a probe. A clone named alpha 403 showed interstrain variations in the length of the EcoRI and HindIII fragments. The EcoRI fragments were either 0.7 or 3 kb, those of HindIII were either 4.5 or 5 kb, and three types were identified as combinations of those fragments in 20 inbred rat strains. These types segregated in backcross progeny as codominant alleles. The locus for the RFLP was thus named A403. Analysis of linkage between the RFLP locus and 13 other loci reveal that the A403 locus was closely linked to the Cs-1 locus (15 +/- 5.2%), which belongs to rat linkage group XIII.

A polymorphism detected in a variable number of tandem repeats (VNTR) of the seminal vesicle secretion (SVS) IV gene in inbred rats

The second intron of the rat SVS IV gene contains a tandem repeat region of 20-bp sequences. This region was amplified using the polymerase chain reaction to detect variations. Three alleles, characterized by amplified fragments of 750, 490, and 390 bp, respectively, were found in 24 strains examined. This variation segregated in F1 and backcross progeny in an autosomal codominant manner. We tentatively designated this locus Svs-4. Analysis of linkages between the Svs-4 locus and other loci revealed that it was closely linked to the Svp-1 (less than 2.9%) and the a (10.0 +/- 6.7%) loci, which belong to rat linkage group IV. The Svp-1 and Svs-4 loci, however, were differently distributed among the inbred rat strains.

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.

Restriction fragment length polymorphisms detected in N-ras-related sequences of rats and their linkage analyses

Novel restriction fragment length polymorphisms (RFLPs) in inbred rats were revealed with the human N-ras gene as probe. Three fragments hybridizing to the probe were detected by Southern blot hybridization under highly stringent conditions, and one of the fragments showed variation in inbred rat strains. Furthermore, on hybridization under low-stringency conditions, an additional fragment hybridizing to the probe was observed, and this fragment also showed interstrain variation. These two variant fragments showed different distributions in 27 inbred rat strains and segregated in backcross progeny as codominant alleles of independent single autosomal loci. Therefore, the loci for these RFLPs were named Nras-1 and Nras-2, respectively. Analyses of linkages between the RFLPs and 11 other loci revealed that the Nras-2 locus was closely linked to the c locus (3.7 +/- 2.6%), which belongs to rat linkage group I.

Novel restriction fragment length polymorphism of the growth hormone gene in inbred rats

A novel restriction fragment length polymorphism in inbred rats was detected by Southern blot analysis with rat growth hormone cDNA as a probe. Four alleles, characterized by PstI fragments of 1.2, 1.1, 0.9, and 0.7 kb, respectively, were detected in 27 strains examined. The same distribution of polymorphisms was observed on digestion of DNAs of these strains with three other enzymes, PvuII, HindIII, and BamHI. Moreover, the same differences in length of allelic restriction fragments were obtained with these restriction enzymes as with PstI. These findings suggested that the polymorphism was caused by insertion or deletion of variable DNA segments in the second intron of the growth hormone gene. Linkage analyses using backcross progeny provided no evidence for close linkage between the restriction fragment length polymorphism locus and 10 other loci examined.