CONTROL OF GENE ACTIVITIES IN THE POLYTENE CHROMOSOMES OF Chironomus tentans BY ECDYSONE AND JUVENILE HORMONE

Abstract

Abstract.-The injection of ecdysone (molting hormone) into chironomid larvae is known to result in the stimulation of specific gene activities (increased RNA synthesis). The morphological manifestation of this gene activation is the formation of a puff. Cytological and autoradiographic analysis of several regions of the salivary gland chromosomes of Chironomus tentans revealed that ecdysone also stimulates Balbiani ring 1. In contradistinction to the puffs, the Balbiani rings are tissue specific and account for a significant percentage of the cell's non-nucleolar RNA.The application of juvenile hormone results in a decreased activity of Balbiani ring 1, suggesting that the two hormones may act antagonistically. In addition, juvenile hormone induces a puff at chromosome region I-19-A and this puff becomes less active after a short-term treatment with ecdysone. These data demonstrate an effect of juvenile hormone on puffing and are the first to demonstrate activation of a Balbiani ring by ecdysone.The original and important observation that the insect molting hormone, ecdysone, can influence the activity of two specific loci on the polytene, salivary gland chromosomes of larval Chironomus tentans, was made a decade ago by Clever and Karlson.I In that case, injection of ecdysone stimulated the formation of puff 1-18-C and caused the regression of puff 1-19-A. This finding, as well as subsequent work on the polytene chromosomes of Diptera, led to the conclusion that ecdysone acts either directly upon the chromosome or indirectly via changes in the ionic environment.2In regard to salivary gland function, however, the activation or deactivation of a puff-forming region can be considered a minor effect since a puff only constitutes between 0.5 to 3.0% of the total non-nucleolar RNA in the salivary gland nucleus.3 4 In addition, the puffs alluded to above1 are not specific to the salivary gland chromosomes.5 The Balbiani rings (BR1, BR2, BR3), on the other hand, are considered to be sites of gene activity specific to the salivary gland chromosomes6 and produce 10-60 times more RNA than a puff.3' 4 The present paper describes the effect of ecdysone on Balbiani ring 1.

Immunological studies on the developmental and chromosomal distribution of ecdysteroid receptor protein in Chironomus tentans

“…These loci do not specifically react with pABcE/D. The tremendous expansion and activation of BR 1 resulting from an Ec-treatment of intermolt fourth instar larvae (Lezzi and Gilbert, 1969) thus has to be ascribed to an indirect effect of Ec. Even within the group of cEcR-positive loci there is no strict correlation between the strengths of signals revealing cEcR and those revealing RNA polymerase 11.…”

Farnesoid secretions of dipteran ring glands: What we do know and what we can know

“…He obtained a weaker phenotype of adults with smaller than normal compound eyes and restrained production of brown eye pigment, while red eye pigment deposition appeared normal. (b) Using the same JH I homolog of methyl farnesoate as above, Lezzi and Gilbert (1969) treated Chironomis tetans larvae and obtained specific repression of ecdysone-activated puff I-18-C, specific induction of ecdysone-repressed puff I-19-A, and specific repression of ecdysone-activated Balbiani Ring BR1. (c) Srivastava and Gilbert (1969) also showed by photographic and histological evidence that application of the JH I homolog of methyl farnesoate directly to the naked body of the fresh cryptocephalic pupa induced small patches of unpigmented, hairless cuticle on the adult thorax.…”

Programmed cell death during metamorphosis in the blow-flyCalliphora vomitoria

“…Changes occur in the apical plasma membrane, the cytoplasm blebs, and the mitochondria condense as in apoptosis. These changes appear to be accompanied by de novo manufacture of proteins and enzymes (Ash- burner Berendes, 1969;Lezzi and Gilbert, 1969) and evidence of selective gene expression . Similar changes have also been observed in metamorphosing Drosophila melanogaster (Jones and Bowen, 1993).…”