Kris White

Drosophila pericardial cells express biotransformation and detoxification enzymes

The developing Drosophila heart is initially composed of cells that differentiate into two cell types: cardioblasts that give rise to the dorsal heart tube and pericardial cells that flank the heart. A number of recent studies have identified key genetic switches that differentiate cardial cells from pericardial cells during development. In addition, the morphology of the pupal and adult heart and pericardial cells has now been studied, but the function of the pericardial cells remains poorly defined. Various functions that have been ascribed to these cells but most often they are said to play a role in hemolymph filtration and detoxification. This function has been assumed based on morphological data, not demonstrated by physiological tests. Studies in moths have linked pericardial cells to the sequestration of juvenile hormone esterase and the production of biliverdin reductase and peroxidase. Drosophila pericardial cells have previously been shown to have endogenous b-galactosidase activity and to express an ecdysteriod UDP-glucosyl/UDP glucuronosyl transferase. Kris is using a combination of subtractive hybridization, standard Northern analysis and in situ hybridization to determine what enzymes pericardial cells express at high levels. A number of enzymes involved in the biotransformation of waste and/or toxic materials, including endogenous peroxidase, and Ugt37c1 are being examined specifically. Other enzymes under study include: cytochromeP-450 monoxygenages and reductases, biliverdin reductase, phenol-O-methyltransferase, N-acetyltransferase and g-glutamethyltransferase.