Electrically induced protein release from Schizosaccharomyces pombe cells in a hyperosmotic condition during and following a high electropulsation

A high-electric-field application of fission yeast cells under hyperosmotic conditions improved the electro-induced release of protein and cytoplasmic enzymes. A cell suspension was pulsed at 12.5 kV/cm for 10 ms in a batch system and immediately postincubated at 30 degrees C. The total protein release rate from cells increased in the hypertonic solutions of 1.5-2.5 M sorbitol to approximately threefold higher than those in the hypotonic and isotonic solutions of 0-0.5 M sorbitol. The protein release rate in 2.0 M sorbitol greatly increased up to 4.5 h and then gradually increased after 7.5 h. The maximum activities of cytoplasmic enzymes, such as alcohol dehydrogenase and 3-phosphoglycerate kinase, were obtained at 7.5 h after electropulsation in 2.0 M sorbitol, yielding approximately 90% of the enzyme activity levels found in spheroplast lysate. On the other hand, the release rates of protease in vacuoles and invertase in periplasmic space did not depend on osmotic solutions during electric pulse application.     

Inter-laboratory evaluation studies of notified ELISA methods for allergic substances (egg)

Inter-laboratory evaluation studies were conducted for the notified ELISA methods for allergic substances (Egg). Standard extracts of egg spiked in extracts of sausage, sauce, cookie, bread and cereal at a level of 5-20 ng/mL as the sample solution were analyzed in replicate in 10 laboratories. Coefficients of variation (CVs) of all three ELISA methods using an Egg Protein ovalbumin ELISA Kit (ovalbumin kit), an Egg Protein ovomucoid ELISA Kit (ovomucoid kit) and a FASTKIT Egg ELISA kit (Egg ELISA kit) were mostly less than 10%. Mean recoveries of the standard extract of egg were over 40% in the three ELISA methods. Repeatability relative standard deviations of egg standard solution in five food extracts were in the ranges of 18.7-25.5%, 18.6-41.8%, 21.3-43.3% for the ovalbumin kit, the ovomucoid kit and the Egg ELISA kit, respectively. Reproducibility relative standard deviations of egg standard solution in five food extracts were 16.8-35.1%, 19.6-35.8%, 24.7-51.1% for the ovalbumin kit, the ovomucoid kit and the Egg ELISA kit, respectively. The detection limits of all the ELISA methods were 4-5 ng/mL in sample solutions. These results suggested that the notified ELISA methods are reliable and reproducible for the inspection of egg protein levels in extracts of sausage, sauce, cookie, bread and cereal.