To observe and study the growth and inhibitions of tumors in laboratory animals, luciferase - luciferin proteins, ATP, genes and all the complex interactions are studied by assessing bioluminescence intensity and the optimum use of sophisticated camera systems. This book concentrates on the applications of bioluminescence imaging (BLI) technique in pre-clinical oncology. It discusses new methods to rapidly spot the impurities at the initial level using the Milliflex system. In addition, the use of bioluminescence resonance energy transfer (BRET) technology to keep a check on protein interaction in living cells is also discussed. Bioluminescent proteins are also used for ultra sensitive optical imaging in living animals, accelerating pH-tolerant luciferase for brighter in-vivo image, and oscillation properties in bacterial bioluminescence. This book presents rare and exceptional studies of seasonal characteristics of oceanic bioluminescence and several other bioluminescence producing organisms.