Effect of P application on CEC,amounts of extractable nutrients,and corn yield in a Hydric Melanudand in the Philippines

In soils, next to nitrogen, phosphorus (P) is the second major growth-limiting factor for plants (Fox 1979). It is probably the most deficient soil-derived plant nutrient in Oxisols, Ultisols, acid Alfisols, and Andisols and the proper development of crops is frequently impossible without the application of P. P deficiency is a major nutritional problem in variable charge soils, especially the Andisols, where applied P is usually converted into an unavailable form. The P added to Andisols in fertilizers is readily sorbed to form noncrystal-line aluminum phosphate materials (Nanzyo 1987). Most uncultivated Andisols also show a very low P fertility and very low recovery of applied P fertilizers by crops (Shoji et al. 1993). In fact, P fixation is one of the growth-limiting factors for crops cultivated in Brazil (Fageria and Filho 1987).     

Measurement of bovine somatotropin (bST) and insulin-like growth factor-1 (IGF-1) in bovine milk using an electrochemiluminescent assay

Bovine somatotropin (bST) and insulin-like growth factor-1 (IGF-1) are peptide hormones that are involved in the regulation of milk production in dairy cows. Because these hormones are present at extremely low concentration in fresh and processed bovine milk, a highly sensitive and specific electrochemiluminescent immunoassay (ECLIA) has been developed to better estimate the concentration of these hormones in milk. The assay employs an imager, a capture antibody bound to a carbon electrode, and a detection antibody coupled to a ruthenium label. In the presence of tripropylamine and an electric pulse, ruthenium generates light proportional to the amount of antigen bound, and the light is captured as signal by a charge-coupled device (CCD) camera. Using bovine milk as the starting matrix, 99.69% of bST and 104.79% of IGF-1 were recoverable. The limit of detection (LOD) was <5 pg/mL for bST and <1 pg/mL for IGF-1. The limit of quantification (LOQ) was <14 pg/mL for bST in milk and <2 pg/mL of IGF-1. The assay is highly specific and shows <0.2% cross-reactivity with other peptide hormones found in bovine milk such as insulin and IGF-2. These data indicate this new, ECLIA is highly sensitive and specific for estimating the concentration of bST or IGF-1 in milk.