Bioinformatics has emerged as an important research tool in recent years. The ability to mine large databases for relevant information has become increasingly central to many different aspects of biochemistry and molecular biology. It is important that undergraduates be introduced to the available information and methodologies. We present a problem-based approach for incorporation of bioinformatics into existing courses. Examples of exercises are presented along with resources available on the World-Wide Web.

Based on the hypothesis that bacteria with minimal embryo lethality might be good candidates for vertical transmission, 103 lactose-positive Escherichia coli isolates were collected from different broiler-related conditions (sources) and analyzed using a variety of in vitro assays: biochemical profiles, sensitivity to antimicrobials, and the presence of plasmids in the 2000- to 16,000-base pair range. The results of these assays were analyzed to determine if they were associated with, or could be used as predictors of, the degree of lethality these isolates produced in 12-day-old embryos. In addition, the in vitro assay results were analyzed to determine if there was any correlation between any particular pair of factors. On the basis of biochemical profiles, the isolates were classified into 17 different groups; however, only a limited number of biochemical reactions separated a majority of the isolates. The isolates varied considerably in the number and size of plasmids they contained and in their sensitivity to the antimicrobials evaluated. The isolates also varied in their ability to kill chicken embryos--killing from 0% to 100% of those inoculated--yet significant differences were detected in lethality based on source and biochemical profile of the isolate. In addition, a predictive model for embryo lethality was constructed and evaluated based on three characteristics of these 103 isolates, namely, their ability to ferment raffinose and sorbose and their sensitivity to gentamicin.

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An NADH-dependent lipid peroxidation system previously identified in channel catfish muscle mierosomes functioned at -10°C in isolated mlcrosomes. Below that, activity was inhibited. The amount of peroxldase activity remaining after thawing previously frozen isolated mlcrosomes or intact catfish fillets was inversely related to storage temperature. Microsome yield and lipid content were lower in the fillets stored at -10°C than -40°C. Most mlcrosomal fatty acids, especially PUFAs, gradually decreased in the fish fillets stored at -10°C. Prolonged storage of catfish fillets would require storage below -20°C. Any thawing would result in reactivation of the peroxldase system.

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