This is a Career Advancement Award to support Dr. Aprille's sabbatical work, which will be carried out in her home institution (Tufts University). The goal of the project is to study molecular-genetic aspects of postnatal development of mitochondrial function in mammalian liver. Dr. Aprille has an established record of productivity in the area of physiological aspects of postnatal mitochondrial development. This sabbatical year will provide her with the opportunity to collaborate with and learn molecular genetic techniques from her colleague, Dr. Susan Ernst. The acquisition of molecular techniques will allow Dr. Aprille to make some unique contributions to her field, and is anticipated to significantly enhance her career.