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1
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Mutational changes in Delphinium malabaricum (Huth.) Munz.: a potential ornamental plant

100%
Kolar F. R., Ghatge S. R., Nimbalkar M. S., Dixit G. B.
Journal of Horticultural Research
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2015
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tom 23
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nr 2
2

The role of mutation frequency decline and SOS repair systems in methyl methanesulfonate mutagenesis

100%
Grzesiuk E.
Acta Biochimica Polonica
|
1998
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tom 45
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nr 2
Methyl methanesulfonate (MMS) is an SN2 type alkylating agent which predominantly methylates nitrogen atoms in purines. Among the methylated bases 3meA and 3meG are highly mutagenic and toxic. The excision of these lesions leads to the formation of apurinic (AP) sites and subsequently to AT-->TA or GC-->TA transversions. The in vivo method based on phenotypic analysis of Arg+ revertants of Escherichia coli K12 and sensitivity to T4 nonsense mutants has been used to estimate the specificity of MMS induced mutations. In the E. coli arg-his-thr- (AB1157) strain MMS induces argE3(oc)-->Arg+ revertants of which 70-80% arise by supL suppressor formation as a result of AT-->TA transversions. The remaining 20-30% arise by supB and supE(oc) suppressor formation as a result of GC-->AT transitions. The level of AT-->TA transversions decreases during starvation. This is a consequence of action of the repair mechanism called mutation frequency decline. This system which is a transcription coupled variant of nucleotide excision repair was discovered in UV induced mutations. We describe the mutation frequency decline phenomenon for MMS mutagenesis. MMS is a very efficient inducer of the SOS response and a umuDC dependent mutagen. In MMS treated E. coli cells mutated in umuDC genes the class of AT-->TA transversions dramatically diminishes. A plasmid bearing UmuD(D')C proteins can supplement chromosomal deletion of umuDC operon: a plasmid harbouring umuD'C is more efficient in comparison to that harbouring umuDC. Moreover, plasmids isolated from MMS treated and transiently starved E. coli AB1157 cells harbouring umuD(D')C genes have shown the repair of AP sites by a system which involves the UmuD'C or at least UmuD' protein.
3
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Frequency and spectrum of induced viable macromutations in chickpea (Cicer arietinum L.) cultivar ‘Vishwas’

80%
Barshile J. D.
International Letters of Natural Sciences
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2015
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tom 03
Present investigation was undertaken to study the frequency and spectrum of induced viable macromutations employing SA, EMS and gamma radiation in chickpea (Cicer arietinum L.) cultivar Vishwas (Phule G 5). The seeds of chickpea, cultivar Vishwas were treated with three different concentrations / doses of SA (2, 3 and 4 mM), EMS (8, 12 and 16 mM) and gamma radiations (400, 500 and 600 Gy). The mutagen administered seeds were sown in experimental fields to raise M1 progeny. Seeds of M1 plants and control were harvested separately and sown to raise M2 population. The M2 progeny were screened for viable macromutaions. A wide spectrum of viable macromutations was isolated in the M2 generation. In all twenty four different types of viable morphological macromutations were observed. These included 7 types of plant type mutations and 6 types of leaf mutations, 1 types of flower mutation, 5 types of pod mutation and 5 types of seed mutations. Results indicated that all mutagenic treatments were effective in inducing viable mutations in chickpea, during M2 generation. Differences in response to different mutagens were observed in the spectrum and frequency of viable mutations. Some mutation types occurred more frequently than others. The frequency and spectrum of viable mutations were relatively high with EMS followed by gamma radiation and SA. In the present investigation, an attempt has been made for increasing frequency and spectrum of locally important chickpea cultivar ‘Vishwas’ employing chemical and physical mutagens.
4
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Estimation of induced mutation rates of four esterase genes in barley [Hordeum vulgare L.]

80%
Kucharska M., Maluszynski M.
Journal of Applied Genetics
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1998
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tom 39
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nr 2
Induced mutation rate of barley esterase loci has been estimated. Results suggested that about 3% of investigated M₁ spikes had seeds which gave rise to M₂ seedlings mutated in one of four esterase loci. M₁ plants were obtained after chemical treatment of seeds from two spring barley cultivars Aramir and Bielik. The majority of mutants were reconfirmed in the М₃ generation.
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