Gene activation following microinjection of β-ecdysone into nuclei and cytoplasm of larval salivary gland cells of drosophila

Abstract

A comparison of the activity of chromosome region 4–78B (puff size) following β-ecdysone injection into nuclei or cytoplasm of larval salivary glands of Drosophila hydei revealed that direct injection of the hormone into the nucleus resulted in a significantly smaller puff size (lower activity) than injection into the cytoplasm. Control experiments indicated that this lower response is not a consequence of damage of the nuclear membrane by the injection. Following nuclear and cytoplasmic injection of β-ecdysone into apical glands cells, region 4–78B becomes active in all cells of the gland. However, puff size decreases with increasing distance between the injected and measured cell nuclei. The results are interpreted in terms of the necessity of a carrier to transport the steroid from the cytoplasm to the nucleus.