Flow injection analysis of serum urea using urease covalently immobilized on 2-fluoro-1-methylpyridinium salt-activated fractogel and fluorescence detection

Serum samples were analyzed for their urea content using fluorescence flow injection analysis incorporating an immobilized urease bioreactor and a gas permeable separator. The urease was immobilized under mild and facile conditions to a hydrophilic 2-fluoro-1-methylpyridinium-activated support. The ammonia released as a result of urease-catalyzed urea hydrolysis diffused through a gas permeable membrane into a constant stream of o-phthaldehyde solution to form a highly fluorescent product with lambda ex at 340 nm and lambda em at 455 nm. Up to 25 serum samples can be analyzed per hour. The within-day coefficient of variation (CV) was 1.12% and the day-to-day CV was 1.25% for serum containing 10.50 mg urea nitrogen dl-1. The bioreactor shows excellent storage (at 4 degrees C) and operational stabilities (at 37 degrees C).     

Reproduction of the House mouse (Mus musculus) in farm buildings

Live and kill traps were used to remove House mice living in granaries, mixed-food stores, dairy units and ancillary stores on farms. Structural weaknesses were common to all buildings. Cavities in walls, in particular, provided favourable living and nesting quarters for mice and were rapidly exploited. The body-weight structure and reproductive traits of the populations in the different habitats were compared. The onset of maturity, in both sexes, was closely related to body-weight increase in the 10 to 14 g range. Breeding, unlike that in most out-door populations in temperate climates, continued throughout the year. Ancillary buildings holding limited food supported small reservoir populations. Mice inhabiting dairy units containing pelleted cattle feed tended to be heavier than those sampled elsewhere and females in the units produced the largest litters. Reproductive performance on farms was intermediate between that of mice occupying urban buildings and corn ricks. There was evidence that environmental and behavioural factors were operating to limit increase in numbers in the dairy units.