Combined imaging and chemical sensing of fertilization-induced acid release from single sea urchin eggs

We demonstrate a microarray sensor capable of obtaining both chemical and v isual information on multiple cells simultaneously with single-cell resolut ion. The array was fabricated by covalently immobilizing a thin, pa-sensiti ve polymer layer on the distal end of an optical imaging fiber. The sensor' s ability to measure localized chemical dynamics in real-time was evaluated using sea urchin fertilization biochemistry as a model system. Following s ea urchin fertilization the Na+/H+ transporter is activated to exchange ext racellular sodium ions for intracellular hydrogen ions, causing a release o f hydrogen ions at the egg's surface. By placing the pH sensor proximal to the egg and switching between a fluorescence image and a white light image, we were able to observe both localized pH changes following fertilization as well as morphological transformations during cell division. (C) 1999 Aca demic Press.