Characterization of six rat strains (Rattus norvegicus) by mitochondrial DNA restriction fragment length polymorphism.

A.W Hilsdorf,J.E Krieger

doi:10.1590/s0100-879x1999000300003

Abstract

Restriction fragment length polymorphism (RFLP) was used to examine the extent of mtDNA polymorphism among six strains of rats (Rattus norvegicus)--Wistar, Wistar Munich, Brown Norway, Wistar Kyoto, SHR and SHR-SP. A survey of 26 restriction enzymes has revealed a low level of genetic divergence among strains. The sites of cleavage by EcoRI, NcoI and XmnI were shown to be polymorphic. The use of these three enzymes allows the 6 strains to be classified into 4 haplotypes and identifies specific markers for each one. The percentage of sequence divergence among all pairs of haplotypes ranged from 0.035 to 0.33%, which is the result of a severe population constriction undergone by the strains. These haplotypes are easily demonstrable and therefore RFLP analysis can be employed for genetic monitoring of rats within animal facilities or among different laboratories.

Highlights

Rats are useful models employed to study cardiovascular physiology and to understand complex pathological states such as hypertension and diabetes mellitus [1]
Three of the 26 endonucleases, ClaI, NheI and SacI, were able to hydrolyze the mtDNA from the 6 Rattus norvegicus strains in only one site
Wistar Kyoto, spontaneously hypertensive rat (SHR), SHR-SP, and Brown Norway rats showed a different pattern that is cited as type III by Brown and Simpson [20] (Figure 1)

Summary

Introduction

Rats are useful models employed to study cardiovascular physiology and to understand complex pathological states such as hypertension and diabetes mellitus [1]. In the late fifties and early sixties several strains of rats were developed for high blood pressure studies by selective intercross to fix a phenotype among individuals of outbred colonies. The spontaneously hypertensive rat (SHR) was obtained by intercrossing individuals of an outbred colony of Wistar Kyoto (WKY) rats with the highest blood pressure values [2]. This process was repeated in other laboratories and today several strains of hypertensive rats with slightly different characteristics exist [3]. Restriction fragment length polymorphism (RFLP) analysis of the nuclear genome was used to measure the level of genetic divergence between SHR and the Wistar-Kyoto rats [9]. Arbitrarily primed polymerase chain reaction (APPCR) was performed to develop nuclear genetic markers and to perform genetic linkage

Methods

Results

Conclusion