Search Results - (Author, Cooperation:M. Etcheverry)

2014-02-08

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Arabidopsis/*genetics ; Chromosome Mapping ; DNA Methylation/*genetics ; *Epigenesis, Genetic ; *Gene Expression Regulation, Plant ; *Quantitative Trait Loci ; Selection, Genetic

0168-9002

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Physics

Electronic Resource

1573-0832

aflatoxin ; sunflower seeds ; Aspergillus parasiticus ; Alternaria ; alternariol ; alternariol monomethyl ether ; interaction of microorganisms

Springer Online Journal Archives 1860-2000

Biology

Medicine

Abstract The aim of the present work was to determine the influence of Alternaria alternata upon aflatoxin production by Aspergillus parasiticus. A mixture of spores of both strains was inoculated in sunflower seeds at 0,90 aw, and incubated for 42 days at 28 °C ±1. The cultures were observed and analyzed every 7 days to determine the infection level of the seeds and the production of aflatoxins. Results showed that when the seeds were inoculated only with Aspergillus parasiticus, 100% were infected from the 7th day. When Aspergillus parasiticus and Alternaria alternata were simultaneously inoculated the infection level of the seeds was 100% for Aspergillus parasiticus following 7 days of inoculation and 0% for Alternaria alternata. After the 14th day of inoculation there was no significant difference in the infection percentage of both strains (approximately 80% of each one). As far as toxin production is concerned a remarkable decrease was observed when seeds were inoculated with both strains simultaneously. In accordance to the results, Alternaria alternata would not compete with Aspergillus parasiticus in colonization of seeds but would either degrade the aflatoxins by Aspergillus parasiticus or compete for aflatoxin biosynthesis precursors. Alternaria alternata could also secrete some substance that specifically inhibits aflatoxin synthesis.

Electronic Resource

1573-0832

corn genotypes ; corn meal ; Aspergillus flavus ; Aspergillus parasiticus ; aflatoxin B1

Springer Online Journal Archives 1860-2000

Biology

Medicine

Abstract A study has been carried out in Argentina on samples of corn genotypes from a breeding station as well as in commercially available corn meal. All samples were analyzed for fungal infection and aflatoxin B1.Mycological analysis of corn genotypes showed the presence of three principal genera of filamentous fungi Fusarium (100%), Penicillium (67%) and Aspergillus (60%). In the genus Fusarium three species were identified, F. moniliforme (42%), F. nygamai (56%) andF. proliferatum (1.8%). Eight species ofPenicillium were identified, the predominant species isolated were P. minioluteum, P. funiculosum and P. variabile. In the genus ranked third in isolation frequency, two species were identified, A. flavus and A. parasiticus, the percentage of infection was 78% and 21%, respectively. Only one corn genotype was contaminated with aflatoxin B1 at a level of 5 ppb. The cornmeal samples showed great differences in fungal contamination, the values ranging from 1 × 101 to 7 × 105 cfu g−1. Fusarium (68%), Aspergillus (35%) and Penicillium (21%) were the most frequent genera isolated. Among the genus, Aspergillus, A. parasiticus (38%) was the most frequent species isolated. All the samples of corn meal were negative to aflatoxin B1. These results indicate a low degree of human exposure to aflatoxins in Argentina through the ingestion of maize or corn meal.

Electronic Resource

1573-0832

Aflatoxin B1 ; zearalenone ; deoxynivalenol ; irradiated maize grain ; Fusarium graminearum ; Aspergillus parasiticus

Springer Online Journal Archives 1860-2000

Biology

Medicine

Abstract The influence of inoculum size in the production of aflatoxin B1 (AFB1), zearalenone (ZEN) and deoxynivalenol (DON) was determined when Aspergillus parasiticus NRRL 3000 and Fusarium graminearum ITEM 124 were cultured alone and in pairs on irradiated corn kernels at 28 °C and 0.97 water activity (aw). The highest levels of AFB1 produced by A. parasiticus were produced at the lowest levels of the inoculum (103 spores/ml). No significant differences were observed in ZEN and DON production at any inoculum level during the experimental period. When A. parasiticus was co-inoculated with F. graminearum both to the same inocula (106 spores/ml), AFB1 inhibition percentage were 60, 72 and 56% at 10, 20 and 35 days of incubation respectively, while at 106 spores/ml the percentages of inhibition were 34, 84 and 93% at 10, 20 and 35 days. In the mixture cultures A. parasiticus 103 × F. graminearum 106 spores/ml the percentage of inhibition of AFB1 oscillated in 99% during all the incubation. In the interaction A. parasiticus 106 spores/ml × F. graminearum 103 spores/ml the accumulation of AFB1 decreased in 80, 94 and 86% at 10, 20 and 35 days of incubation respectively. In single culture F. graminearum was inoculated with 103 or 106 spores/ml and the highest levels of ZEN and DON were detected at 35 days of incubation. The levels oscillated in 538–622 μg/kg for ZEN and 870–834 μg/kg for DON respectively. In paired cultures there were no significant differences in the levels regardless of the spore concentrations during the incubation time.

Electronic Resource

1573-0832

aflatoxin ; sunflower seeds ; Aspergillus parasiticus ; zinc

Springer Online Journal Archives 1860-2000

Biology

Medicine

Abstract Growth and aflatoxin production by Aspergillus parasiticus NRRL 2999 and Aspergillus parasiticus RC 12 were studied both in sunflower seed and a synthetic culture medium (with and without zinc enrichment). On a synthetic culture medium the strains behaved in different ways according to the zinc concentration. In sunflower seed medium the influence of zinc was not so evident. Thus the results show that the influence of zinc is not the same for different strains and substrates.

Electronic Resource

1588-2780

Springer Online Journal Archives 1860-2000

Chemistry and Pharmacology

Energy, Environment Protection, Nuclear Power Engineering

Abstract Nowadays large interest is attached to the production of exotic beams and targets for nuclear structure and reaction studies. The nucleus178Hf, with is long-lived (T 1/2=31 years) high-spin isomeric statel π=16+ at a relatively low-excitation energy (2.446 MeV), is indeed a unique probe for studying phenomena in a new way. A wide research program has been underway in the framework of the “Hafnium Collaboration” which now concems around 80 scientists. Various targets have been prepared and adapted to different types of experiments. Irradiation processes with high-intensity beams, high-purity chemistry methods and isotopic separations have been developed. The obtaining of appreciable amounts of very high purity178m2Hf by isotopic separation, has made it possible for us to carry out γ-ray measurements with good statistics and high energy resolution with a γ-spectrometer, in order to use this isomer as a calibration standard in the 200 to 600 ke V energy range. For example, relative to the main γ-rays, energies have been determined with an absolute uncertainty of about 2 e V and photon emission probabilities with a relative uncertainty better than 1%.

Electronic Resource