High Spontaneous Mutation Research Articles

Disease of plants VKDVST (VCDTST) and occurrence of high frequency and wide spectrum of spontaneous mutations at Solanum lycopersicum L

The origin and inheritance high frequency and wide spectrum spontaneous mutation in posterity of double mutant of line Novichock-mini-j-2 of kind Solanum lycopersicum L. which were accompanied by simultaneous disease of plants by the virus cluster deformations of a top of a stem of a tomato (VCDTST), is found out. The average frequency of mutations in 2010–2012 years had index 22.82% or 1 plant to 4.4. Every year were fixed 12–14 mutant traits, including resistance to virus in 2011–2012 years. The mutant genes are localized in 6 different chromosomes By the genetic analysis the influence of the transposons of sexual cells (TSC), controlling dominant or recessive states of genes at a level of the whole organism are found out. TSC are differ from earlier known somatic transposons controlling chimerical spottiness tissue of corn, leaves and flours plants. The conditions connected with occurrence of spontaneous mutational process and possibility of it use in breeding are analyzed.

Differences in induction of sister chromatid exchanges in MNNG-resistant Hela S3 Mer−cell lines

All N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-resistant (MR) cell lines of HeLa S3 Mer- cells tested were found to be defective in O6-methylguanine-DNA methyltransferase and more sensitive than HeLa Mer+ cells to 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)-1-nitroso-ure a, like the parental HeLa S3 Mer- cells. MR10-1 and MR1-3 cells were also highly resistant to induction of sister chromatid exchanges (SCEs) by MNNG, while MR6, MR8 and MR11 cells were slightly resistant to SCE induction, MR10-1 and MR1-3 cells showed higher spontaneous mutation rates than the parental cells. These results indicated that there are at least two types of MR cells. All MR cells were more sensitive than HeLa S3 Mer- cells to 6-hydroxyamino purine.

Studies on the mutability of Escherichia coli K12 : I. Suppression and high spontaneous mutation in a threonine auxotroph

Strain TH 1014 of Escherichia coli K12 Hfr H is a leaky mutant requiring l-threonine for growth and has a very high rate of spontaneous reversion to prototrophy. Through conjugation experiments with appropriate F − strains, it was found that the leakiness in this strain was due to the existence of a gene ( mod) locating near the leu locus and modifying a threonine deficiency ( thr 1014) at the usual threonine site and the reversions to complete prototrophy took place at a site ( fgr) residing between the gal and try loci. These genetic sites regarding threonine reversion of the strain TH 1014 were transferred by conjugation into F − strains. Studies with these reconstructed female strains, as well as those with original male strains, showed that strains carrying thr 1014 mod + and fgr spontaneously mutated, frequently in the order of 10 −4, but those carrying thr 1014 mod and fgr did not. These studies also indicated that, at least in a few revertant strains examined, the co-existence of mod + and fgr + together with thr 1014 might be necessary for active growth in the absence of threonine. Studies on the growth of mutants of T4 carrying the amber or ochre nonsence codons suggested that neither the mod + nor the fgr + gene is a suppresor for these nonsense codons.