Honeybee trophocytes and fat cells as target cells for cellular senescence studies.

Trophocytes and fat cells are distributed around the abdominal segments in honeybees (Apis mellifera). Whether these cells are a good model for cellular senescence studies is unknown. Here we used histochemical, biochemical, and genetic techniques to investigate the fluctuation of age-related molecules in trophocytes and fat cells of newly emerged and old worker bees. Histochemical studies revealed that old worker trophocytes and fat cells exhibited more senescence-associated β-galactosidase, lipofuscin granules, and non-homogeneous cellular morphology compared to the same cells in newly emerged workers. Biochemical assays demonstrated that trophocytes and fat cells of old workers expressed more lipid peroxidation and protein oxidation than those of newly emerged workers. Molecular genetic analyses detected no difference in telomerase activity or telomere length in trophocytes and fat cells between newly emerged and old workers, showing that these cells do not divide in adulthood. These results suggest that the expression of age-related molecules in trophocytes and fat cells is associated with the senescence of the cells and that honeybee trophocytes and fat cells can serve as a mode for cellular senescence.