Real-time in vivo uric acid biosensor system for biophysical monitoring of birds.

Research on birds has long played an important role in ecological investigations, as birds are relatively easily observed, and their high metabolic rates and diurnal habits make them quite evidently responsive to changes in their environments. A mechanistic understanding of such avian responses requires a better understanding of how variation in physiological state conditions avian behavior and integrates the effects of recent environmental changes. There is a great need for sensor systems that will allow free-flying birds to interact with their environment and make unconstrained decisions about their spatial location at the same time that their physiological state is being monitored in real time. We have developed a miniature needle-based enzymatic sensor system suitable for continuous real-time amperometric monitoring of uric acid levels in unconstrained live birds. The sensor system was constructed with Pt/Ir wire and Ag/AgCl paste. Uricase enzyme was immobilized on a 0.7 mm sensing cavity of Nafion/cellulose inner membrane to minimize the influences of background interferents. The sensor response was linear from 0.05 to 0.6 mM uric acid, which spans the normal physiological range for most avian species. We developed a two-electrode potentiostat system that drives the biosensor, reads the output current, and wirelessly transmits the data. In addition to extensive characterization of the sensor and system, we also demonstrate autonomous operation of the system by collecting in vivo extracellular uric acid measurements on a domestic chicken. The results confirm our needle-type sensor system's potential for real-time monitoring of birds' physiological state. Successful application of the sensor in migratory birds could open up a new era of studying both the physiological preparation for migration and the consequences of sustained avian flight.

Hot Acidified Cupric Acetate Soaks for Eradication of Xanthomonas campestris from Crucifer Seeds.

Acidified cupric acetate soaks were tested for eradication of Xanthomonas campestris from naturally infected crucifer seeds. The pathogen was eradicated from seeds by soaking in 0.5% cupric acetate dissolved in 0.005 N acetic acid for 20 min at 35, 40, 45, and 50 degrees C but not 25 degrees C. Moreover, normal bacterial flora of crucifer seeds and the seed-borne Phoma lingam and Alternaria spp. were reduced by 95, 92, and 81%, respectively, after the cupric acetate treatment at 40 degrees C. The seed germination percentage was generally reduced, but the amount of reduction depended upon the treatment temperature and plant cultivar. At 50 degrees C, less than 50% of the seed of all 12 cultivars tested germinated, whereas at 40 degrees C more than 50% of the seeds of most cultivars germinated. Treating seeds in cupric acetate at 40 degrees C should prove useful for eradicating X. campestris from seeds of breeding lines and stock seed used for hybrid seed production. Furthermore, a significant reduction in total bacterial flora and seed-borne fungi suggests the usefulness of the treatment for other microorganisms associated with other seeds or foodstuffs.