Inherited enhancement of hydroxyl radical generation and lipid peroxidation in the S strain rats results in DNA rearrangements, degenerative diseases, and premature aging.

Previously by selection and inbreeding of Wistar rats susceptible or resistant to the cataractogenic effect of galactose the S and R rat strains differing in the intensity of hexose transport into the animal cells were developed. High level of OH-radical generation and enhanced lipid peroxidation are revealed in the liver and myocardium of the S rats in contrast to the R rats. Data are obtained supporting the view that enhanced generation of OH-radicals within the S rat tissues is due to oxidation and autooxidation of the abundant amounts of monosacharides intensely accumulating in the rat cells. In spite of continuous inbreeding for more than 40 generations and a high rate of homozygosity, numerous DNA rearrangements are revealed in the S rat genomes. Fragility of the S rat cell membranes is detected. Cataracts and other lens lesions, emphysema, tumors, cardiomyopathy-like changes in the myocardium, scoliosis, brain disfunctions are characteristic of the S rats, as well as low fertility and short life-span indicative of premature aging.

Expression of mitochondrial genes in fertile and sterile sugar beet cytoplasms with different nuclear fertility restorer genes.

Variations in mitochondrial genome organization and in its expression between fertile, sterile sugar beet lines and fertile nuclear-restored plants were studied. Southern blot hybridization with COXI, COXII, COB and atpA mitochondrial genes as probes showed that changes in the mitochondrial genome organization of sterile lines are associated with variations in the location of COB, atpA and COXII, but not COXI. When the COXII and atpA genes were used as hybridization probes, differences in the primary structure of mitochondrial DNAs from sterile lines of different origin were revealed. Differences in the transcriptional patterns of the three mitochondrial genes (COXI, COXII and atpA) were observed between fertile and sterile sugar beet lines; COB was the only mitochondrial gene whose transcription was identical in both fertile and sterile cytoplasms. The dominant nuclear fertility restorer genes altered the transcriptional patterns of the COB and atpA without affecting those of the COXI and COXII genes; atp A expression was identical in fertile plants and nuclear-restored plants with sterile cytoplasm.

High-rate spontaneous reversion to cytoplasmic male sterility in sugar beet: a characterization of the mitochondrial genomes.

Among the fertile sugar beet lines with nuclear sterility maintenance genes, rf, in a homozygous recessive state, sublines capable of reverting spontaneously at a high rate to sterility were identified. Of 24 related fertile sublines studied, 6 were found to spontaneously revert to sterility with a frequency of about 19%. Genetic analysis confirmed the cytoplasmic nature of spontaneously arising sterility. Reversion to sterility in these sublines was accompanied by alterations in the mitochondrial genome structure: loss of the autonomously replicating minicircle c (1.3 kb) and changes in the restriction patterns of high-molecular-weight mitochondrial DNA (mtDNA). Southern hybridixation analysis with cloned minicircle c as a probe revealed no integration of this DNA molecule into the main mitochondrial and nuclear genomes of the revertants. Comparative BamHI and EcoRI restriction analysis of the mtDNA from the sterile revertants and fertile parental subline showed that the spontaneous reversion is accompanied by extensive genomic rearrangement. Southern blot analysis with cloned α-subunit of F1-ATPase (atpA) and cytochrome c oxidase subunit II (COX II) genes as probes indicated that the changes in mtDNA accompanying spontaneous reversion to sterility involved these regions. The mitochondrial genomes of the spontaneous revertants and the sterile analogue were shown to be identical.