Mutagenicity studies of cadmium chloride in mice

Cadmium chloride [CdCl2] was tested for its mutagenicity in Swiss albino mice by the dominant lethal mutation test and the micronuclei test singly or in combination with either nitrosoguanidine [NTG] or ascorbic acid. The results obtained showed that cadmium chloride is a weak mutagen when compared with NTG as a positive control. However, cadmium chloride [CdCl2] and NTG in combination showed a significant increase in the dominant lethal mutations when compared with the effect of either CdCl2 or NTG individually. A statistically significant increase of the frequency of micronucleated erythrocytes was also noticed when CdCl2 was combined with either NTG or ascorbic acid compared with CdCl2 individually

Characterization and mapping of an informational suppressor in Aspergillus nidulans

The present work was undertaken to characterize a suppressor gene present in a mutant strain of A. nidulans obtained with NTG (N-Methyl-N'-Nitro-N-Nitrosoguanidine). Analyses of this mutant have shown that this suppressor, designated suO1, induces phenotypic co-reversion of several auxotrophic mutations and makes the strain sensitive to aminoglycoside antibiotics and lower temperatures. suO1 has shown to be on linkage group VIII. The vegetative growth of the mutant strain is very unstable because the suppressor gene induces the production of prototrophic mitotic sectors. The strains bearing the suO1 gene produce cleistothecia containing a reduced number of viable ascospores during the sexual cycle. The segregation of the genetic markers has also been observed in the mutant strain self crossed. From the above results it may be concluded that suO1 is an informational suppressor.

Suinin an antibiotic produced by a mutant of streptomyces nasri [Hashim and Diab]

Suinin is an antibiotic produced by a nitrosoguanidine mutant of Streptomyces isuri. This antibiotic is active against Gram-positive bacteria. The effect of temperature, pH, xubation period in addition to trace elements and different carbon and nitrogen sources on both growth and antibiotic production were investigated

Suinin, an antibiotic produced by a mutant of stretomtyces nasri [Hashem and Diab]

Suinin, is an aromatic anti-Gram-positive antibiotic obtained from a nitrosoguanidine mutant of Streptomyces nasri. The antibiotic was purified as reddish needles [Ig/OL]. UV, 1R,H-NMR,[13C-]NMR and mass spectra were performed in addition to Cosy and APT tests. The chemical formula of suinin was found to C[31]H[37]NO[5]. A proposed structure for suinin is included. The MIC for suinin against Bacillus subtilis ATCC 6633 was 1.5mg/ml, 2.0mg/ml against both Sarcina lutea OSUCC 495 and Staphylococcus aureus OSUCC 209 and 2.5mg/ml against Staphylococcus aureus OSUCC.680. Also, the interaction of suinin with some representatives of the widely used antibiotics was investigated. The result of this investigation recommended suinin to be an acceptable synergizer for some -lactam antibiotics, most aminoglycosidic antibiotics and some miscellaneous as polymyxin B, chtoramphenicol, minocycline, fusidic acid and rifampicin

Zearalenone production in fusarium graminearum variants after treatment with nitrosoguanidine

A Zearalenona é um metabólito secundário produzido por Fusarium graminearum e, aparentemente, envolvido no controle de sua reproduçäo sexuada. Em alguns animais, quando ingerida, provoca efeitos estrogênicos. A reduçäo química da Zearalenona produz o derivado zearalenol, que possui efeito anabolizante em bois e ovelhas, predominando sobre o efeito estrogênico. A partir de um isolado de Fusarium graminearum, considerado bom produtor de zearalenona, investigou-se, através da açäo do mutagênico nitrosoquanidina sobre seus conidios, a possibilidade de obtençäo de variantes com maior produçäo de zearalenona. Foram selecionadas 40 amostras em funçäo de seus aspectos morfológicos, pigmentaçäo e tempo de crescimento compatíveis com exemplares mais produtores de zearalenona em isolamento natural. Através de quantificaçäo de zearalenona em HPLC, obtiveram-se 10 variantes com produçäo entre 2 a 16 vezes supeiror ao controle quando do seu isolamento. A estabilidade destes variantes foi testada através de 12 transferências sucessivas em meio de cultivo. Nas condiçöes testadas obtiveram-se 2 variantes considerados estáveis e que mantiveram a superproduçäo de zearalenona

lethal and mutagenic effect of N-Methyl-N-Nitroso guanidine [MnnG] on Escherichia coli

Comparing the characters of the mutants and their parent strains, the isolated mutants were found to be different in some morphological and colonial characters, haemolysin production, haemagglutination activity, biochemical reactions and antibiotic sensitivities

nitrosoguanidines mediated adaptive repair in pseudomonas syringae

Adaptive repair activity has been demonstrated in wild type cells of Ps. syringae. MNNG mediated [adapted] cells resisted more than the nonadapted cells. Treatment of the cells with protein synthesis inhibiting antibiotic chloramphenicol at a concentration of 100 micro gml -1 during adaptation prevented the enhanced resistance to killing effects of MNNG. However, such an effect was not demonstrated when the cells were treated with chloramphenicol during the MNNG challenge treatment of the adaptive cells. It is, therefore, evident that adaptive repair in Ps. syringae is mediated as a result of the induced synthesis of enzymes

Induction of genetic variabilities in Saccharomyces cerevisiae G104-g using UV and nitrosoguanidin treatment for bakery II Revised carbohydrates, proteins and amino acid content

1112 mutants were selected by exposing the haploid strain. S. cerevisiae G104-g to differing doses of UV or NTG. The mutants produced by using UV followed by dark having a protein value that varied between 28.5% to 41.08%. While the corresponding value presented in the same mutants produced by UV followed by light was ranged from 37.52% to 52.17%. The total carbohydrates of the mutant produced by the former method realized slightly higher level than that of the latter one. On the other hand, mutants obtained by NTG treatment in different time show that the protein index number could be descendingly arranged from 55.07% to 56.1%. While the total reserved carbohydrates reached 39.55% as a maximum value in the mutant B/NTG 90/12, it reached only 28.56% and 28.48% in the mutant B/NTG 30/8 and C/NTG 60/17, but also proved that the carbohydrates of the mutants formed with UV followed by light were approximately within the range of the chemical treatment. The best selected mutants B/NTG 90/ 12 and L/4/11 contained approximately similar identified amino acids of S. cerevisiae G104-g [the wild type] with a real difference in their values. This may show a way to improve the concentration of specified amino acids. Balady bread based on mutant B/NTG 90/12 as well as mutant L/4,/11 came in the first organoleptic evaluation order in relation to those made with the wild type, B/NTG 90/12, L/4/11. S. cerevisiae B and the commercial S. cerevisiae. Mutants lead to the production of bread of higher quality

Genetic analysis of compact mutants of Aspergillus nidulans.

Foram isolados doze mutantes compactos de Aspergillus nidulans que apresentaram alem do reduzido crescimento, escassa producao de conidios, enrugamento da colonia em graus variaveis e alteracoes na coloracao do micelio. Eles foram obtidos a partir de linhagens normais apos tratamento com luz ultra violeta ou nitrosoguanidina. A analise genetica efetuada mostrou que sete dos mutantes apresentaram segrecao normal (1:1), enquanto que os demais mutantes apresentaram segrecao complexa indicando a ocorrencia de aberracoes cromossomicas envolvendo um ou dois grupos de ligacao. Os determinantes morfologicos foram localizados em quase todos os grupos de ligacao conhecidos, exceto para o III e VI. O consumo de oxigenio medido atraves do respirometro de Warburg foi menor nos mutantes compactos variando de 26 a 86% em relacao a linhagem normal