IMMUNOHISTOCHEMICAL LOCALIZATION OF ECDYSTEROID RECEPTOR AND ULTRASPIRACLE IN THE EPITHELIAL-CELL LINE FROM CHIRONOMUS-TENTANS (INSECTA, DIPTERA)

Ecdysteroid receptor (EcR) and its heterodimerization partner, ultrasp iracle (USP), were demonstrated in the epithelial cell line from Chiro nomus tentans by immunohistochemistry. In untreated cells both protein s are present in nuclei as well as in granular compartments of the cyt osol, At 1 day after addition of 1-mu M 20-OH-ecdysone (20E) total imm unofluorescence had increased in the nuclei, whereas the cytoplasmic s taining had disappeared. At the 2nd and 3rd days all cells within a ve sicle appear identical according to morphological criteria, but the Ec R and USP immunoreactivity becomes restricted into patches of neighbou ring cells. The hormonally induced changes in the pattern of localizat ion of functional ecdysteroid receptor, the heterodimer of EcR and USP , are discussed in relation to similar effects of 20E on acetylcholine sterase and muscarinic acetylcholine receptor distribution in this cel l line.