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At least 19 recordsLinked to original sources
PubMed1983

The structural genes for three Drosophila glue proteins reside at a single polytene chromosome puff locus.

The polytene chromosome puff at 68C on the Drosophila melanogaster third chromosome is thought from genetic experiments to contain the structural gene for one of the secreted salivary gland glue polypeptides, sgs-3. Previous work has demonstrated that the DNA included in this puff contains sequences that are transcribed to give three different polyadenylated RNAs that are abundant in third-larval-instar salivary glands. These have been called the group II, group III, and group IV RNAs. In the experiments reported here, we used the nucleotide sequence of the DNA coding for these RNAs to predict some of the physical and chemical properties expected of their protein products, including molecular weight, amino acid composition, and amino acid sequence. Salivary gland polypeptides with molecular weights similar to those expected for the 68C RNA translation products, and with the expected degree of incorporation of different radioactive amino acids, were purified. These proteins were shown by amino acid sequencing to correspond to the protein products of the 68C RNAs. It was further shown that each of these proteins is a part of the secreted salivary gland glue: the group IV RNA codes for the previously described sgs-3, whereas the group II and III RNAs code for the newly identified glue polypeptides sgs-8 and sgs-7.

Amino Acid Sequence↗
PubMed1977

[Age specificity of the effect of 5-bromdeoxyuridine on the differentiation and spectra of chromosomal puffs in the salivary glands of Drosophila virilis Sturt. II. Alteration of the puff spectrum in salivary gland chromosomes].

The expressivity and temporal patterns of function of the various puff groups are changed, when larvae of Drosophila virilis are kept on BUdR containing medium during different periods of their larval development, as compared with the control animals kept on BUdR-free media. The magnitude of the effect depends on the stage at which the treatment is conducted; the larvae of the 3rd instar are more sensitive to BUdR. The effect of BUdR becomes considerably lower by the end of the 3rd instar period.

Age Factors↗
PubMed1996

The Drosophila Eip78C gene is not vital but has a role in regulating chromosome puffs.

We have generated a number of chromosomal aberrations that disrupt the early-late ecdysone-induced 78C puff gene (Eip78C, ecdysone-induced protein, FlyBase name for the E78 gene of Stone and Thummel 1993), which encodes the two members of the nuclear hormone receptor superfamily Eip78C-A and Eip78C-B. The aberrations include deletions of the ligand-binding/dimerization domain of both, inversions that split Eip78C-A but retain residual Eip78C-B expression, and a small deletion specific for Eip78C-B. We find that wild-type Eip78C functions are completely dispensable for normal development under laboratory conditions. However, we show that Eip78C-B is required for the maximal puffing activity of a subset of late puffs (63E and 82F) since these puffs are reduced in size in Eip78C-B mutant backgrounds. Paradoxically the same late puffs are reduced, as well as at least one other, when the Eip78C-B cDNA is overexpressed from a heat shock promoter. These data indicate either that Eip78C function is redundant or that it plays a subtle modulating role in the regulation of chromosome puffing.

Amino Acid Sequence↗
PubMed1984

Steroid regulation of RNAs transcribed from the Drosophila 68c polytene chromosome puff.

The 68C region of the Drosophila melanogaster salivary gland polytene chromosomes harbors the structural genes for the three salivary gland glue proteins sgs-3, sgs-7, and sgs-8. This region is puffed during the third larval instar, the stage when glue proteins are being produced in the salivary glands. The puff regresses near the end of the third instar as a result of an increased titer of the steroid hormone ecdysterone in the larval hemolymph. The experiments reported here were designed to determine whether the ecdysterone effect on puffing at 68C is correlated with hormone effects on expression of the three puff RNAs. In the first series of experiments, it is shown that there is a more rapid disappearance of 68C RNA transcripts from salivary glands cultured in the presence of ecdysterone than from glands cultured in its absence. The second set of experiments, in which 68C transcripts were pulse-labeled in salivary glands cultured in the presence or absence of hormone, demonstrates that one effect of ecdysterone is to cause a sharp reduction in the rate at which newly synthesized 68C transcripts accumulate. The final experiments follow the time required for ecdysterone to produce this effect, and show that it occurs in salivary glands exposed to the hormone for as little as 15 min. In all of the experiments, the RNA products of the Sgs-3, Sgs-7, and Sgs-8 genes acted coordinately.

Animals↗
PubMed2004

Studies of the role of the Drosophila scs and scs' insulators in defining boundaries of a chromosome puff.

Insulators are DNA elements that establish independent transcriptional domains within eukaryotic genomes. The Drosophila scs and scs' insulators localize near the borders of a structural domain in the polytene chromosomes, known as a puff, produced by transcription of the 87A heat shock protein (hsp) genes. It has been suggested that scs and scs' are boundary elements that delimit this decondensed chromatin domain, reflecting the mechanism by which these sequences act to constrain regulatory interactions. This model was tested using transposons that carried a yellow gene to assess enhancer blocking and an hsp70-lacZ gene to examine the structure of a heat shock puff in the presence and absence of insulators. We found that although scs and scs' blocked enhancer function, these sequences did not prevent the spread of decondensation resulting from hsp70-lacZ transcription. Further analysis of the endogenous 87A locus demonstrated that scs and scs' reside within, not at, the borders of the puff. Taken together, our studies suggest that scs and scs' are not boundary elements that block the propagation of an altered chromatin state associated with puff formation. We propose that these insulators may have a direct role in limiting regulatory interactions in the gene-dense 87A region.

Animals↗
PubMed1975

Chromosome puff activity and protein synthesis in larval salivary glands of Drosophila melanogaster.

Secretion proteins from larval salivary glands of Drosophila melanogaster were analyzed with acrylamide gel electrophoresis. Four fractions were found; three showed electrophoretic variants in different wild-type stocks. Crossbreeding and cytogenetic techniques were used to localize the genes responsible for the two main fractions: The gene for fraction 3 was found to lie within a segment of the third chromosome which includes section 68C; the gene for fraction 4, Sgs-4, was found to lie within section 3C8-3D1 of the X chromosome (1 - 3-5). The puffs within these sections of the giant chromosomes are active before and during secretion synthesis and become inactive as secretion synthesis ceases. Larvae of one wild-type stock which lack protein fraction 4 do not exhibit any puffing in 3C. The relative amount of protein 4 in the salivary secretion shows a marked dependence on the dosage of the Sgs-4 gene in both duplication and deficiency genotypes. The active site within puff 3C11-12 apparently contains the structural gene for protein 4.

Chromosome Mapping↗
PubMed1977

Direct correlation between a chromosome puff and the synthesis of a larval saliva protein in Drosophila melanogaster.

The structural gene Sgs-4 responsible for larval saliva protein 4 of Drosophila melanogaster was localized, with the help of Notch deficiencies, within the section between bands 3C10 and 3D1 of the X chromosome. In this chromosome section there is, very probably, only one fine band. In the third larval instar chromosome this section is transcriptionally active and forms a puff. When the ecdysone concentration increases, about 5 h before prepupa formation, it becomes inactive.--In section 3C of X chromosomes of third instar larvae of the stock Hikone-R no puff is formed. The saliva of these larvae lacks protein 4. However, female hybrids (H/B and H/O) from Hikone-R crossed with Berlin and Oregon respectively produce a Hikone-specific saliva protein 4h. The synthesis of protein 4h in the hybrids H/B and H/O is ascribed to an activation of the gene Sgs-4 in the Hikone chromosome.--In the saliva of heterozygotes (FM1/H) carrying one inversion chromosome In(1)FM1 and one X chromosome from Hikone, protein 4h could not be detected. In these inversion heterozygotes in 90% of all nuclei the homologues are not paired in 3C, and 3C is puffed only in the FM1 chromosome. This suggests that a precondition for the activation of Hikone gene Sgs-4 in heterozygotes may be intimate homologue pairing.--Intersexes with one of their X chromosomes from Hikone-R and the other from Berlin produce relatively more protein 4h than do diploid H/B females, indicating facilitated transcription as a result of dosage compensation.

Animals↗