Single-stranded deoxyribonucleic acid (ssDNA) thymidylic acid icosanucleotides (dT20) were synthesized on the surfaces of derivatized quartz optical fibers to create an optical DNA biosensor. The synthesis made use of an automated solid-phase synthesizer and phosphoramidite synthons. The covalently immobilized oligomers were found to hybridize with complementary ssDNA (cDNA) or ssRNA (cRNA) from solution, and the device was regenerable for multiple cycles of application. Hybridization on optical fibers was detected by the use of the fluorescent DNA stain ethidium bromide (EB). The procedure used hybridization assay techniques and provided a detection limit of 86 ng x mL(-1) cDNA and a sensitivity of 200% fluorescence intensity increase per 100 ng x mL(-1) of cDNA, with one cycle of hybridization analysis requiring 45 min. The sensor has been observed to be regenerable (minimum of five cycles) and to sustain full activity after prolonged storage times (1 year), harsh washing conditions (sonication), and sterilization (autoclaving). The extent of hybridization between the immobilized and complementary nucleic acid strands was determined by UV absorbance thermal denaturation studies wherein all 20 bases on each strand of the nucleic acid were found to be involved in duplex formation.

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During the summer of 1980, there was a great deal of rainfall and high humidity in southwestern Ontario. Sprouting of the kernels on plants in the field and pink discoloration down-graded the white winter wheat crop. Samples were submitted to Agriculture Canada from elevators and boats loading wheat for export. Chemical analyses indicated low levels of vomitoxin, with some analytical results as high as 8.5 ppm. A series of feeding trials was initiated with contaminated wheat (1.0 ppm vomitoxin) to determine effects on swine and poultry. Swine diets containing 0.3 and 0.7 ppm vomitoxin resulted in decreased feed consumption and weight gains. Poultry were fed similar levels of vomitoxin without any serious effects. Gross examination of internal organs at the termination of the subacute studies revealed no apparent toxic effects. Several farmers reported feed refusal, vomiting and death in their livestock. Chemical analyses, in general, revealed relatively low levels of vomitoxin. In one case, the level of vomitoxin (0.95 ppm) in the feed was high enough to he a possible contributing factor in the observed ill effects.

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Deoxynivalenol (DON), an occasional contaminant of foodstuffs, has been implicated in outbreaks of mycotoxicosis. Balb-c mice that had ingested 0.35 mg/kg of DON showed a drastic decrease in food intake and concomitant loss of weight. Severe depletion of the lymphoid organs and liver were also observed. Cardiac lesions, appeared as calcified pericarditis foci in young animals fed a diet contaminated by 10 to 20 ppm of DON for a period of a few weeks. DON inhibited protein synthesis. This inhibition occurred at lower doses for the heart than for the other organs. This preferential effect on cardiac tissue correlated with the cardiotoxicity observed.