Transcriptional regulation in Drosophila during heat shock: a nuclear run-on analysis.

We used a nuclear run-on assay as a novel approach to study the changes in transcriptional activity that take place in Drosophila melanogaster during heat shock. In response to a rapid temperature upshift, total transcriptional activity in cultured KC161 cells decreased proportionally to the severity of the shock. After extended stress at 37 degrees C (15 min or more), transcription was severely reduced, and at 39 degrees C most transcription was instantaneously arrested.

Heat shock response in Drosophila.

Major alterations in genetic activity have been observed in every organism after exposure to abnormally high temperatures. This phenomenon, called the heat shock response, was discovered in the fruit fly Drosophila. Studies with this organism led to the discovery of the heat shock proteins, whose genes were among the first eukaryotic genes to be cloned.

Tissue-specific expression of the heat shock protein HSP27 during Drosophila melanogaster development.

The alpha-crystallin-related heat shock (stress) protein hsp27 is expressed in absence of heat shock during Drosophila melanogaster development. Here, we describe the tissue distribution of this protein using an immunoaffinity-purified antibody. In embryos, hsp27 translated from maternal RNA is uniformly distributed, except in the yolk.

Expression of the small heat shock genes during Drosophila development: comparison of the accumulation of hsp23 and hsp27 mRNAs and polypeptides.

Seven heat shock genes are clustered within 15 kilobases of DNA at the Drosophila melanogaster chromosomal site 67B. They show a complex pattern of expression in the absence of external stress during normal development of this organism. In this paper, we quantitatively compare the abundance of the messenger RNAs for these seven genes at all major stages of Drosophila development and then focus on hsp23 and hsp27 for which available antibodies allow the comparison between the accumulation of the mRNAs and that of their corresponding polypeptides.

Several hundred base pairs upstream of Drosophila hsp23 and 26 genes are required for their heat induction in transformed flies.

We have used the P-element-mediated transformation of Drosophila germ line to study the 5' DNA sequences involved in the thermal inducibility of the genes for heat shock proteins hsp23 and 26. The results are strikingly different from those previously obtained in heterologous systems. For hsp23, each successive shortening of the promoter region from 618 to 402, 321 and 263 bp clearly decreased the expression.

Locus 67B of Drosophila melanogaster contains seven, not four, closely related heat shock genes.

The four small hsp genes of Drosophila melanogaster as well as three genes regulated during development (genes 1, 2 and 3) are localized at the chromosomal locus 67B. The four small hsp genes share strong sequence homologies between themselves which were detected here by cross-hybridization. Under the same stringency conditions, each of the genes 1, 2 and 3 hybridize to some of the small hsp genes.

Nucleotide sequences responsible for the thermal inducibility of the Drosophila small heat-shock protein genes in monkey COS cells.

The promoter regions of the Drosophila melanogaster small heat-shock protein genes have been analysed in order to localize those sequences responsible for their heat-shock transcriptional inducibility. Different lengths of the 5' DNA sequences of these four genes were each fused individually to the Herpes simplex virus thymidine kinase (HSV-tk) transcription unit. These hybrid genes were constructed in a simian virus 40 recombinant vector for transfection in permissive monkey COS cells and tested for their heat-shock inducibility.

A DNA segment isolated from chromosomal site 67B in D. melanogaster contains four closely linked heat-shock genes.

cDNA clones coding for two different small heat-shock polypeptides were isolated. Both clones hybridize exclusively to the heat-shock puff site 67B, and restriction mapping of embryonic Drosophila melanogaster DNA showed that the two genes probably occur as single copies and are closely linked. The analysis was extended by isolating genomic clones, which contain these genes and two additional ones.

Physical map of two D. melanogaster DNA segments containing sequences coding for the 70,000 dalton heat shock protein.

The isolation of the two hybrid plasmids 56H8 and 132E3, which contain D. melanogaster (Dm) DNA sequences complementary to the mRNA coding for the 70,000 dalton heat shock protein, has been reported (Schedl et al., 1978).

Two hybrid plasmids with D. melanogaster DNA sequences complementary to mRNA coding for the major heat shock protein.

The isolation and partial characterization of two cloned segments of Drosophila melanogaster DNA containing "heat shock" gene sequences is described. We have inserted sheared embryonic D. melanogaster DNA by the poly(dA-dt) connector method (Lobban and Kaiser, 1973) into the R1 restriction site of the ampicillin-resistant plasmid pSF2124 (So, Gill and Falkow, 1975).

Heat shock of Drosophila melanogaster induces the synthesis of new messenger RNAs and proteins.

The heat shock proteins, labelled in vivo with [35S]methionine, were separated by sodium dodecylsulphate-polyacrylamide gel electrophoresis and fingerprinted after tryptic digestion. Eight distinct heat shock polypeptides are characterized in this way. Heat shock messenger RNAs were isolated and partially purified.