Mapping of the beige (bg) gene on rat chromosome 17

An allele-specific genotyping method for rat lyst (lysosomal trafficking regulator) gene

Two spontaneous mutant beige rats, with phenotypes resembling human Chediak- Higashi syndrome (CHS), were found independently in two inbred strains. Both beige mutations were identified to be recessive alleles in the Lyst locus on rat chromosome 17 and the alleles were denoted Lyst(bg) and Lyst(bg-Kyo). As it is almost impossible to discriminate these mutations phenotypically, we developed an allele-specific genotyping method for the Lyst gene. The nested PCR amplification was followed by restriction fragment length polymorphism (RFLP) analysis. By this method, we could discriminate the mutant Lyst(bg), Lyst(bg-Kyo) alleles, and the normal Lyst allele, easily and accurately.

Postrest contraction in the ventricular papillary muscle of spontaneously diabetic WBN/Kob rat

In the present study, we investigated the characteristics of the postrest contraction (PRC) in chronic diabetic ventricular muscle. We used WBN/Kob rats of 7-8 weeks as the spontaneously diabetic animal and Wistar rats of 7-8 weeks as the control. We found: (1) No significant differences were seen in the amplitude, the contracting speed, and the relaxing speed of electrically stimulated twitch tension between control and WBN/Kob rats. In addition, the relationship between amplitude of twitch tension and stimulus cycle lengths (0.2-5 sec) was very similar in both animals. (2) The ratios of the first twitch tension (T1) of PRC with various rest intervals (5-600 sec) to the steady-state tension (Tss) were significantly smaller in the diabetic rats than in the controls. (3) When the preparation was stimulated at shorter cycle lengths, the recovery process of PRC was separated into at least two components (fast and slow components). In the diabetic rats, the time constant (tau) of both components was significantly longer than in controls. (4) After caffeine (10(-3) M) treatment, tau of the fast component in the control rats became longer, whereas it remained unchanged in diabetic rats. These findings suggest a dysfunction of the intracellular calcium handling system in spontaneously diabetic heart that is likely to include impaired calcium sequestration and/or extrusion.