CHANGES IN THE DISTRIBUTIONS OF CHEMICAL-ELEMENTS IN REGENERATING SCALES OF CARP, CYPRINUS-CARPIO, STUDIED BY SRXRF IMAGING

Two-dimensional distributions of calcium, phosphorus, strontium, and z inc in regenerating scales of carp, Cyprinus carpio, were observed ove r a period of 90 days by utilizing synchrotron radiation-excited X-ray fluorescence (SRXRF) imaging. On the 15th day, these elements were hi ghly accumulated in the part that is exposed to the ambient water, and the accumulated amount decreased linearly toward the basal edge throu gh the focal area of the scale. As the regeneration progressed, this c haracteristic pattern changed such that the amount of each element in the rim part, which was exposed to the ambient water, obviously increa sed, while the amount in the basal edge decreased. However, the relati ve amounts of phosphorus, strontium, and zinc with respect to calcium in the regenerating scale remained almost constant during the regenera tion. In addition, it was found that the diameter of, and the number o f ridges in, the regenerating scales increased rapidly during the firs t 15 days, and increased at a slower pace later on.