Seigo Shumiya

High Susceptibility of an Analbuminemic Congenic Strain of Rats with an F344 Genetic Background to Induced Bladder Cancer and Its Possible Mechanism

The susceptibility of an analbuminemic congenic strain of rats (F344‐alb) originating from the F344 strain to N‐butyl‐N‐(4‐hydroxybutyl)nitrosamine (BBN) was examined. F344‐alb rats were found to be highly susceptible to induction of urinary bladder cancers. The incidences of bladder cancers in F344‐alb and F344 rats were 94% (15/16) and 31% (5/16) in males and 100% (16/16) and 19% (3/16) in females. The bladder weights of these rats, including tumors, were 307±294 mg, 123±26 mg, 183±80 mg and 93±11 mg, respectively. Administration of 0.05%, 0.1% and 0.3% BBN in the drinking water for 2 weeks resulted in greater increases in the bladder content of N‐butyl‐N‐(3‐carboxypropyl)nitrosamine in F344‐alb rats than in F344 rats. This increase was prevented by the presence of rat albumin.

Mapping of the hooded, Gc protein, and albumin gene loci in linkage group VI of the laboratory rat

Crosses to determine the position of the three gene loci,h, Gc, andAlb, in the sixth linkage group of the rat used three strains, the TM strain, the ACI-alb analbuminemic congenic strain, and the abh-alb tester strain established by crossing the abh coat color tester strain and analbuminemic rats. Their genotypes were[C/C, h/h, GcB/GcB, Alb/Alb], [C/C, hi/hi,GcA/GcA, alb/alb] and[C/C, h/h, GcA/GcA, alb/alb], respectively. Determination of genotypes was performed by coat color and polyacrylamide gel electrophoresis (PAGE) of serum protein for theGc and albumin genes. The positions of the three gene loci in the VI linkage group were calculated from the recombination values from the phenotypes of progenies. According to this data, the three gene loci were inh-Gc-Alb tandem and the distances were 15.5±1.0% inh-Gc, 15.8±1.0% inh-Alb, and 0.32±0.16% inGc-Alb. These data confirmed the relationship among theGc, Alb, andApf genes in the rat as well as in humans.

Albumin-Deficient Rat: Nagase Analbuminemia Rat(NAR).

In 1979, we established an analbuminemic rat mutant strain (Nagase Analbuminemia Rat; NAR) from Sprague-Dawley rats. Using NARs, a number of important findings were obtained. This paper is focused on the genetic analysis, mapping of genes, and the structural analysis of albumin gene in NAR.Analbuminemia in NAR is inherited as an autosomal recessive trait (designated alb) . The albumin gene is mapped tandem to hooded (h), Vitamin D-binding protein (Gc), and Alb loci in VI linkage group of chromosome 14, h-Gc; 15.5 ± 1.0%, h-Alb; 15.8 ± 1.0%, and Gc-Alb; 0.32 ± 0.16%, respectively. The alb gene has a seven-base-pair deletion in HI intron. This mutation blocks albumin mRNA splicing in NAR liver. NAR might be the most useful model for the understanding mechanism of splicing in a high animal species.

Identification of a Protein Increasing in Serum of Nagase Analbuminemic Rats Bearing Intestinal Tumors as an Isotype of T‐Kininogen

ABSTRACT Increase in an unidentified protein was observed in serum of Nagase analbuminemic rats (NAR) bearing intestinal tumors induced by azoxymethane. This protein seemed to be a polymer of a protein of 73 kDa as estimated by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis, and so was tentatively named 73K‐protein. The serum concentration of 73K‐protein in NAR bearing intestinal tumors was 11.9 ± 2.2 mg/ml (mean ± SD, n = 5), whereas that in control NAR was 2.0 ± 0.2 mg/ml. Increase of the serum 73K‐protein level was also observed in Sprague‐Dawley rats bearing intestinal tumors, skin tumors, subcutaneous sarcomas, or mammary tumors and in ACI rats bearing urinary bladder tumors. On double immunodiffusion analysis, the 73K‐protein was not detected in mouse, guinea pig, pig, horse, or human serum. A cDNA clone bearing the sequence encoding 73K‐protein was isolated from a cDNA library constructed from rat liver mRNA. The nucleotide sequence of the 73K‐protein showed 98.8% and 96.9% homologies with the sequences of the 3′‐proximal domains of the cDNAs for TI‐ and TII‐kininogen, respectively. Therefore, the 73K‐protein was concluded to be an isotype of T‐kininogen.