De novo t(2;13)(p24.3;q14.2) and retinoblastoma

Summary The two probes H3-8 and H2-42, known to be located in 13q14, were mapped by in situ hybridization to either side of the 13 breakpoint of an apparently balanced de novo t(2;13)(p24.3;q14.2) detected in a patient with retinoblastoma as the only phenotypic manifestation.     

Design of solid state fermentor for production of fungal metabolites on large scale

Summary A large scale solid state fermentor of 150 tray capacity is designed with appropriate control system. It gave better productivity even at higher scale of operation as compared to lab and large scale units of similar type and largely overcomes some operational problems.     

Variation in N2 fixation,N and P contents of mycorrhizalVigna unguiculata in relation to the progressive development of extraradical hyphae ofGlomus mosseae

Summary Vigna unguiculata cv. 58–185 grown in a sterile Dek soil was inoculated withRhizobium sp. orRhizobium sp. plusGlomus mosseae. Response of the host plant to the treatments was estimated by periodic measurements of shoot and nodule dry weights, N₂ fixation (C₂H₂ reduction activity) and N and P contents up to the 50th day of the growth cycle. It was only 45 days after planting that shoot dry weight of dually inoculated plants differed significantly from that of plants inoculated withRhizobium sp. alone. Nodule dry weight and N₂ fixation of dually inoculated plants were significantly higher than those of plants inoculated withRhizobium sp. alone from day 20 after planting, but there was no significant difference in N content (%). During the first 20 days, shoot P content (%) of both sets of plants decreased progressively, P content of dually inoculated plants being lower than that of the others. Later, P content of dually inoculated plants increased rapidly whereas P content of the other plants remained constant. Increase in nodule dry weight, N₂ fixation and P content of dually inoculated plants corresponded to the onset of the development of the extra-radical hyphae ofGlomus mosseae. In the rhizosphere.

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Resumen Se cultivóVigna unguiculata cv. 58–185 en un suelo estéril tipo Dek, se inoculó conRhizobium sp. o conRhizobium sp. másGlomus mosseae. La respuesta de la planta huésped a los tratamientos se estudió midiendo periodicamente el peso seco de la parte aerea y de los nódulos, la fijación de N (actividad reductora de C₂H₂) y los contenidos de N y P hasta el 50° día del ciclo de crecimiento. La diferencia entre el peso seco de la parte aerea de las plantas con doble inoculación y aquellas inoculadas conRhizobium sp. unicamente, no fue significativa hasta 45 días despúés de la siembra. A los 20 días de la siembra tanto el peso seco de los nódulos como la fijación de nitrógeno de las plantas con doble inoculación eran significativamente superiores a los valores obtenidos para las plantas con soloRhizobium sp., aunque no se observaron diferencias en el contenido en N (%). Durante los primeros 20 días del ciclo el contenido en P (%) de ambos grupos de plantas disminuyó progresivamente, siendo los valores obtenidos por las plantas con doble inoculación inferiores a los de las demás. Más tarde el contenido en P de las plantas con doble inoculación aumentó rapidamente manteniéndose constante el de las demás. El incremento en el peso seco de los nódulos, en la fijación de N y en el contenido en P de las plantas con doble inoculación se correspondió con el inicio del desarrollo de las hifas extraradiculares deGlomus mosseae.

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Résumé On a inoculéV. unguiculata poussant dans un sol Dek stérile avecRhizobium etRhizobium plusGlomus mosseae. On a recherché la réponse de la plante-hôte à ces deux traitements en estimant périodiquement les poids des nodules et des parties aériennes de la plante, la fixation d'azote (activité réductrice de C₂H₂), les teneurs en N et P jusqu'au 50^e jour du cycle de végétation. C'est seulement au 45^e jour après la plantation que le poids sec des parties aériennes des plantes inoculées avec deux symbiotes (plantes doublement inoculées) diffère significativement de celui des plantes inoculées avec Rhizobium seul. Le poids sec des nodules et la fixation N₂ des plantes doublement inoculées sont significativement plus élevés que ceux des plantes inoculées avecRhizobium seul au 20^e jour après la plantation mais il n'y a pas de différence significative pour la teneur en N (%). Pendant les 20 premiers jours, la teneur en P (%) des parties aériennes des deux catégories de plantes décroit progressivement; la teneur en P des plantes doublement inoculées est plus faible que celle des plantes inoculées seulement avecRhizobium. Plus tard, la teneur en P des plantes doublement inoculées augmente rapidement tandis que celle des autres plantes reste constante. L'accroissement du poids sec des nodules, de la fixation d'azote et de la teneur en P observé chez les plantes doublement inoculées correspond au démarrage du développement des hyphes extra-radicales deGlomus mosseae dans la rhizosphère.

     

Protective role of potentially lethal damage repair in the neoplastic transformation of Balb/c 3T3 cells treated with N-methyl-N'-nitro-N-nitrosoguanidine

To determine the role of repair of potentially lethal damage (PLD) in the initiation process of neoplastic transformation, Balb/c 3T3 cells treated with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) were temporarily exposed to conditioned medium obtained from density-inhibited Chinese hamster cell cultures, as a post-treatment for the induction of PLD repair. With or without this exposure, cell survival and transformation frequencies were simultaneously determined by colony-formation and focus-formation assays, respectively. Temporary exposure to conditioned medium resulted in a 20-30% increase in cell survival compared with no exposure. Post-treatment with conditioned medium resulted in a 60-65% reduction in transformation frequencies. At the molecular level, the repair of MNNG-induced single-strand breaks of DNA occurred much more rapidly in conditioned medium. These data suggest that PLD repair reduces the in vitro neoplastic transformation through excision repair operative during the cessation of DNA replication. Thus, PLD repair appears to be preventive against neoplastic fixation in initiation of neoplastic development.     

Mutagenicity of nitro- and amino-substituted phenazines in Salmonella typhimurium

The nitro- and amino-substituted phenazines were synthesized and assayed for their mutagenicity in Salmonella typhimurium strains TA98 and TA98NR. Of 7 tested nitrophenazines, 4 were mutagenic in the absence of a microsomal metabolic activation system (S9 mix) and were more mutagenic in TA98 than in TA98NR. The order of mutagenicity of nitrophenazines in TA98 is 1.7- less than 2- less than 2.8- less than 2.7-substituted phenazine. Of 7 tested amino derivatives, 4 exhibited mutagenic activity with S9 mix in TA98. 1-Nitro-, 1-amino, 1.6-dinitro-, 1.9-dinitro-, 1.6-diamino- and 1.9-diamino-phenazine were not mutagenic. As regards the relationship between mutagenic potency and chemical structure of the phenazines, the results suggested that structural requirements favoring mutagenic activity were the presence of substituents at the 2 and/or 7 position. Furthermore, 2.7-disubstituted phenazines were extremely mutagenic, 2.7-dinitrophenazine and 2.7-diaminophenazine induced 36,450 and 12,110 rev./nmole, respectively. In the preliminary study, 2.7-diaminophenazine was identified by gas chromatography/mass spectrometry from the reaction mixture of m-phenylenediamine and hydrogen peroxide.     

Negative micronucleus tests on caprolactam and benzoin in ICR/JCL male mice

Male ICR/JCL mice were given a single intraperitoneal injection of 125, 250, and 500 mg/kg of caprolactam (CAP), or 250, 500, and 1000 mg/kg of benzoin (ZOIN). Bone marrow preparations were made 24, 30, and 48 h after treatment with the maximum dose, and 30 h after treatment with the other doses. The slides were coded before microscopic examination. No significant increase was found in the incidence of micronucleated polychromatic erythrocytes after treatment with either CAP or ZOIN.     

Mutagenicity of the reaction products of carbazole in the presence of nitrogen dioxide and nitrocarbazole

The mutagenicity of the photochemical reaction products of carbazole in the presence of nitrogen dioxide (NO2) and nitrocarbazole was investigated using a high-pressure mercury lamp (100 W). Samples extracted from the photochemical reaction products of carbazole with NO2 were more mutagenic than those of acridine and phenazine with NO2 for Salmonella typhimurium strain TA98 in the absence of S9 mix with a trend toward detoxification in the presence of the metabolic system. The mutagenicity of the photochemical reaction products of carbazole with NO2 were higher than those of the reaction products of carbazole with a mixture of NO2 and sulfur dioxide (SO2) and no irradiation. Mononitro- and dinitro-carbazole in the samples extracted from the reaction products were analyzed by mass spectrometry. It was suggested that mononitrocarbazole, which seemed to be weakly mutagenic, and dinitrocarbazole were readily formed by the reaction of carbazole with NO2, and that the other high-potency mutagens were formed by the photochemical reaction of carbazole with NO2 with irradiation by light.     

Effect of the uvs-2 allele of Neurospora crassa on the mutagenic potency of two N-hydroxylaminopurines and 2-aminopurine in the ad-3 forward-mutation test

The mutagenic potencies of 3 purine analogs were determined in the ad-3 forward-mutation test in growing cultures of heterokaryon 59 (H-59), a nucleotide excision repair-deficient (uvs-2/uvs-2) 2-component heterokaryon of Neurospora crassa. Two N-hydroxylaminopurines, 2-amino-6-N-hydroxylaminopurine (AHA) and 6-N-hydroxylaminopurine (HAP), were potent and strong mutagens, respectively, whereas 2-aminopurine (AP) was a moderate mutagen. Dose-response curves showed that AHA and HAP were about equally mutagenic at low doses but that AHA was more mutagenic than HAP at high doses. Comparison of these results in H-59 with our earlier results in heterokaryon 12 (H-12) of N. crassa, which is identical to H-59 except for being DNA-repair-proficient (uvs-2+/uvs-2+), shows that the defect in nucleotide excision repair due to uvs-2 has little or no effect on the mutagenic potencies of these 3 purine analogs. Therefore, the nucleotide excision-repair pathway in N. crassa that is deficient in H-59 does not appear to have a major role in the repair of pre-mutational lesions induced by these 3 purine analogs. On the other hand, based on the controls of these experiments, the frequency of spontaneous ad-3 mutants was 4 greater in H-59 than in H-12. This result suggests that the nucleotide excision-repair pathway in N. crassa that is inactivated by the uvs-2 mutation has a major role in the repair of lesions that would lead to spontaneous mutation at the ad-3+ region if they were not repaired.