SEX-RELATED AND AGE-RELATED CHANGES IN THE BIOPHYSICAL PROPERTIES OF CUTICULAR LIPIDS OF THE HOUSEFLY, MUSCA-DOMESTICA

We examined the biophysical properties of cuticular lipids isolated fr om the housefly, Musca domestica. Melting temperatures (T-m) of surfac e lipids isolated from female houseflies decreased from 39.3 degrees C to 35.3 degrees C as the females attained sexual maturity and produce d sex pheromone, whereas those prepared from males did not change with age. Lipids melted over a 10-25 degrees C temperature range, and thei r physical properties were a complex function of the properties of the component lipids. The T-m of total cuticular lipids was slightly belo w that of cuticular hydrocarbons (HC), the predominant lipid fraction. Hydrocarbons were further fractionated into saturated, unsaturated, a nd methyl-branched components. The order of decreasing T-m was total a lkanes > total HCs > methyl-branched alkanes > alkenes. For 1-day-old flies, measured T(m)s of hydrocarbons were 1.3-5.5 degrees C lower tha n T(m)s calculated from a weighted average of T(m)s for saturated and unsaturated components. For 4-day-old flies, calculated T(m)s underest imated T-m by 11-14 degrees C. (C) 1995 Wiley-Liss, Inc.