Drosophila chorion gene amplification requires an upstream region regulating s18 transcription

1986 ◽  
Vol 6 (12) ◽  
pp. 4624-4633
Author(s):  
T L Orr-Weaver ◽  
A C Spradling
Keyword(s):  
Gene Expression ◽  
Ovarian Follicle ◽  
Follicle Cells ◽  
Upstream Region ◽  
Transcription Control ◽  
The Third ◽  
Chorion Genes ◽  
Specific Amplification ◽  
Essential Region ◽  
Per Se

A cluster of Drosophila melanogaster chorion genes at locus 66D on the third chromosome amplifies 60-fold in the ovarian follicle cells prior to the onset of gene expression. A 3.8-kilobase (kb) region of the gene cluster can induce tissue-specific amplification in transformants. Previous models postulated that amplification is activated in follicle cells by transcription of one of the two chorion genes (s15 and s18) located within the 3.8-kb essential region. In this study, we showed that neither s15 nor s18 chorion gene transcription was required for amplification. However, a 510-bp region upstream from s18 contained sequences essential for both amplification and s18 transcription. No other region within the 3.8-kb fragment was required for amplification. We propose that upstream transcription control elements rather than transcription per se are involved in controlling amplification during development.

scholarly journals Drosophila chorion gene amplification requires an upstream region regulating s18 transcription.

1986 ◽  
Vol 6 (12) ◽  
pp. 4624-4633 ◽  
Author(s):  
T L Orr-Weaver ◽  
A C Spradling
Keyword(s):  
Gene Expression ◽  
Ovarian Follicle ◽  
Follicle Cells ◽  
Upstream Region ◽  
Transcription Control ◽  
The Third ◽  
Chorion Genes ◽  
Specific Amplification ◽  
Essential Region ◽  
Per Se

A cluster of Drosophila melanogaster chorion genes at locus 66D on the third chromosome amplifies 60-fold in the ovarian follicle cells prior to the onset of gene expression. A 3.8-kilobase (kb) region of the gene cluster can induce tissue-specific amplification in transformants. Previous models postulated that amplification is activated in follicle cells by transcription of one of the two chorion genes (s15 and s18) located within the 3.8-kb essential region. In this study, we showed that neither s15 nor s18 chorion gene transcription was required for amplification. However, a 510-bp region upstream from s18 contained sequences essential for both amplification and s18 transcription. No other region within the 3.8-kb fragment was required for amplification. We propose that upstream transcription control elements rather than transcription per se are involved in controlling amplification during development.

Drosophila chorion gene amplification: a model system for the study of chromosome replication

1984 ◽  
Vol 307 (1132) ◽  
pp. 239-245
Keyword(s):  
Dna Replication ◽  
Dna Sequences ◽  
Ovarian Follicle ◽  
Model System ◽  
P Element ◽  
Follicle Cells ◽  
Tissue Specific ◽  
Chorion Genes ◽  
Specific Amplification

Two chromosomal domains of 80-100 kilobases containing Drosophila chorion genes undergo tissue-specific amplification in ovarian follicle cells during oogenesis. We have investigated the ability of small segments of DNA from within these regions to induce amplification after insertion into new chromosomal sites by P element-mediated transformation. Certain transduced chorion DNA sequences initiated a pattern of tissue-specific differential replication that was identical to norm al chorion amplification. Both the transformed chorion DNA as well as flanking rosy DNA sequences underw ent amplification. O ur results suggest that differential chorion DNA replication is mediated by specific origin-containing sequences located near the centre of the amplified domains. The possible role of such sequences in normal programmes of replication is discussed.

scholarly journals Visualization of Drosophila melanogaster chorion genes undergoing amplification.

1988 ◽  
Vol 8 (7) ◽  
pp. 2811-2821 ◽  
Author(s):  
Y N Osheim ◽  
O L Miller ◽  
A L Beyer
Keyword(s):  
Time Frame ◽  
Maximum Activity ◽  
Follicle Cells ◽  
Control Element ◽  
Active Gene ◽  
Chorion Genes ◽  
Temporal Specificity ◽  
Preferential Amplification ◽  
Essential Region ◽  
Large Clusters

We visualized by electron microscopy the preferential amplification of Drosophila chorion genes in late-stage follicle cells. Chromatin spreads revealed large clusters of actively transcribed genes of the appropriate size, spacing, and orientation for chorion genes that were expressed with the correct temporal specificity. Occasionally the active genes were observed within or contiguous with intact replicons and replication forks. In every case, our micrographs are consistent with the hypothesis that the central region of each chorion domain contains a replication origin(s) used during the amplification event. In one case, a small replication bubble was observed precisely at the site of the essential region of the X chromosome amplification control element. The micrographs also suggest that forks at either end of a replicon frequently progress very different distances, presumably due to different times in initiation or different rates of movement. It appears that all chorion genes (even those coding for minor proteins) are transcribed in a "fully on" condition, albeit for varied durations, and that if replication fork passage does inactivate a promoter, it does so very transiently. Furthermore, a DNA segment containing one active gene is likely to have an additional active gene(s). Surprisingly, during the time frame of expected maximum activity, approximately half of the chorion sequences appear transcriptionally inactive.

scholarly journals The Function of the Broad-Complex During Drosophila melanogaster Oogenesis

Genetics ◽  
1999 ◽  
Vol 153 (3) ◽  
pp. 1371-1383
Author(s):  
George Tzolovsky ◽  
Wu-Min Deng ◽  
Thomas Schlitt ◽  
Mary Bownes
Keyword(s):  
Gene Expression ◽  
Dna Replication ◽  
Zinc Finger ◽  
Target Genes ◽  
Ectopic Expression ◽  
Follicle Cells ◽  
Chorion Genes ◽  
Broad Complex ◽  
Late Expression

Abstract The Broad-Complex (BR-C) is an early ecdysone response gene that functions during metamorphosis and encodes a family of zinc-finger transcription factors. It is expressed in a dynamic pattern during oogenesis. Its late expression in the lateral-dorsal-anterior follicle cells is related to the morphogenesis of the chorionic appendages. All four zinc-finger isoforms are expressed in oogenesis, which is consistent with the abnormal appendage phenotypes resulting from their ectopic expression. We investigated the mechanism by which the BR-C affects chorion deposition by using BrdU to follow the effects of BR-C misexpression on DNA replication and in situ hybridization to ovarian mRNA to evaluate chorion gene expression. Ectopic BR-C expression leads to prolonged endoreplication and to additional amplification of genes, besides the chorion genes, at other sites in the genome. The pattern of chorion gene expression is not affected along the anterior-posterior axis, but the follicle cells at the anterior of the oocyte fail to migrate correctly in an anterior direction when BR-C is misexpressed. We conclude that the target genes of the BR-C in oogenesis include a protein essential for endoreplication and chorion gene amplification. This may provide a link between steroid hormones and the control of DNA replication during oogenesis.

Organization of regionally expressed silkmoth chorion genes

1986 ◽  
Vol 6 (9) ◽  
pp. 3215-3220
Author(s):  
A K Hatzopoulos ◽  
J C Regier
Keyword(s):  
Gene Expression ◽  
Follicle Cells ◽  
Gene Copy ◽  
Late Period ◽  
Chorion Genes ◽  
Copy Numbers ◽  
Total Dna ◽  
Dna Strand ◽  
Gene Copy Numbers ◽  
Silkmoth Chorion

We described the organization of two silkmoth chorion genes, called E1 and E2, whose expression is largely restricted in time to the very late period of choriogenesis and in space to one of two major subpopulations of follicle cells. Using E1 and E2 clone cDNAs as probes, we showed that gene copy numbers per haploid genome remain constant throughout silkmoth development despite major changes in total DNA content per nucleus. Furthermore, gene copy numbers are the same in both cellular regions of the choriogenic follicle despite differences in nuclear size and levels of E gene expression. Southern analysis indicated between two and four copies each for E1 and E2 genes. Analysis of chromosomal clones showed that single copies of E1 and E2 are separated by about 7.5 kilobases and are transcribed from the same DNA strand. Two distinct pairs of cloned E1 and E2 genes were characterized. No other chorion genes were in their immediate vicinity.

Visualization of Drosophila melanogaster chorion genes undergoing amplification

1988 ◽  
Vol 8 (7) ◽  
pp. 2811-2821
Author(s):  
Y N Osheim ◽  
O L Miller ◽  
A L Beyer
Keyword(s):  
Time Frame ◽  
Maximum Activity ◽  
Follicle Cells ◽  
Control Element ◽  
Active Gene ◽  
Chorion Genes ◽  
Temporal Specificity ◽  
Preferential Amplification ◽  
Essential Region ◽  
Large Clusters

We visualized by electron microscopy the preferential amplification of Drosophila chorion genes in late-stage follicle cells. Chromatin spreads revealed large clusters of actively transcribed genes of the appropriate size, spacing, and orientation for chorion genes that were expressed with the correct temporal specificity. Occasionally the active genes were observed within or contiguous with intact replicons and replication forks. In every case, our micrographs are consistent with the hypothesis that the central region of each chorion domain contains a replication origin(s) used during the amplification event. In one case, a small replication bubble was observed precisely at the site of the essential region of the X chromosome amplification control element. The micrographs also suggest that forks at either end of a replicon frequently progress very different distances, presumably due to different times in initiation or different rates of movement. It appears that all chorion genes (even those coding for minor proteins) are transcribed in a "fully on" condition, albeit for varied durations, and that if replication fork passage does inactivate a promoter, it does so very transiently. Furthermore, a DNA segment containing one active gene is likely to have an additional active gene(s). Surprisingly, during the time frame of expected maximum activity, approximately half of the chorion sequences appear transcriptionally inactive.

scholarly journals Multiple replication origins are used during Drosophila chorion gene amplification.

1990 ◽  
Vol 110 (4) ◽  
pp. 903-914 ◽  
Author(s):  
M M Heck ◽  
A C Spradling
Keyword(s):  
Gene Amplification ◽  
Regulatory Elements ◽  
Follicle Cells ◽  
The Third ◽  
Multiple Origins ◽  
Chorion Genes ◽  
D Region ◽  
Egg Chambers ◽  
Replication Intermediates ◽  
Multiple Replication

DNA from Drosophila egg chambers undergoing chorion gene amplification was analyzed using the two-dimensional gel technique of Brewer and Fangman. At stage 10, 34% of DNA molecules from the maximally amplified region of the third chromosome chorion gene cluster contained replication forks or bubbles. These nonlinear forms were intermediates in the process of amplification; they were confined to follicle cells, and were found only within the replicating region during the time of amplification. Multiple origins gave rise to these intermediates, since three separate regions of the third chromosome chorion locus contained replication bubbles. However, initiation was nonrandom; the majority of initiations appeared to occur near the Bgl II site located between the s18 and s15 chorion genes. The P[S6.9] chorion transposon also contained abundant replication intermediates in follicle cells from a transformed line. Initiation within P[S6.9] occurred near two previously defined cis-regulatory elements, one near the same Bgl II site (in the AER-d region) and one near the ACE3 element.

scholarly journals Transcriptional Repressor Functions of Drosophila E2F1 and E2F2 Cooperate To Inhibit Genomic DNA Synthesis in Ovarian Follicle Cells

2003 ◽  
Vol 23 (6) ◽  
pp. 2123-2134 ◽  
Author(s):  
Pelin Cayirlioglu ◽  
William O. Ward ◽  
S. Catherine Silver Key ◽  
Robert J. Duronio
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Dna Synthesis ◽  
Gene Amplification ◽  
Cell Cycle Progression ◽  
Ovarian Follicle ◽  
Cell Cycle Control ◽  
Control Cell ◽  
Follicle Cell ◽  
Follicle Cells

ABSTRACT Individual members of the E2F/DP protein family control cell cycle progression by acting predominantly as an activator or repressor of transcription. In Drosophila melanogaster the E2f1, E2f2, Dp, and Rbf1 genes all contribute to replication control in ovarian follicle cells, which become 16C polyploid and subsequently undergo chorion gene amplification late in oogenesis. Mutation of E2f2, Dp, or Rbf1 causes ectopic DNA replication throughout the follicle cell genome during gene amplification cycles. Here we show by both reverse transcription-PCR and DNA microarray analysis that the transcripts of prereplication complex (pre-RC) genes are elevated compared to the wild type in E2f2, Dp, and Rbf1 mutant follicle cells. For some genes the magnitude of this transcriptional derepression is greater in Rbf1 than in E2f2 mutants. These differences correlate with differences in the magnitude of the replication defects in follicle cells, which attain an inappropriate 32C DNA content in both Rbf1 and Dp mutants but not in E2f2 mutants. The ectopic genomic replication of E2f2 mutant follicle cells can be suppressed by reducing the Orc2, Orc5, or Mcm2 gene dose by half, indicating that small changes in pre-RC gene expression can affect DNA synthesis in these cells. We conclude that RBF1 forms complexes with both E2F1/DP and E2F2/DP that cooperate to repress the expression of pre-RC genes, which helps confine DNA synthesis to sites of gene amplification. In contrast, E2F1 and E2F2 repressors function redundantly for some genes in the embryo. Thus, the relative functional contributions of E2F1 and E2F2 to gene expression and cell cycle control depends on the developmental context.

scholarly journals Organization of regionally expressed silkmoth chorion genes.

1986 ◽  
Vol 6 (9) ◽  
pp. 3215-3220 ◽  
Author(s):  
A K Hatzopoulos ◽  
J C Regier
Keyword(s):  
Gene Expression ◽  
Follicle Cells ◽  
Gene Copy ◽  
Late Period ◽  
Chorion Genes ◽  
Copy Numbers ◽  
Total Dna ◽  
Dna Strand ◽  
Gene Copy Numbers ◽  
Silkmoth Chorion

We described the organization of two silkmoth chorion genes, called E1 and E2, whose expression is largely restricted in time to the very late period of choriogenesis and in space to one of two major subpopulations of follicle cells. Using E1 and E2 clone cDNAs as probes, we showed that gene copy numbers per haploid genome remain constant throughout silkmoth development despite major changes in total DNA content per nucleus. Furthermore, gene copy numbers are the same in both cellular regions of the choriogenic follicle despite differences in nuclear size and levels of E gene expression. Southern analysis indicated between two and four copies each for E1 and E2 genes. Analysis of chromosomal clones showed that single copies of E1 and E2 are separated by about 7.5 kilobases and are transcribed from the same DNA strand. Two distinct pairs of cloned E1 and E2 genes were characterized. No other chorion genes were in their immediate vicinity.

scholarly journals Activator-independent gene expression in Neurospora crassa

Genetics ◽  
1996 ◽  
Vol 142 (2) ◽  
pp. 417-423
Author(s):  
Wayne K Versaw ◽  
Robert L Metzenberg
Keyword(s):  
Gene Expression ◽  
Neurospora Crassa ◽  
Chromosomal Rearrangement ◽  
Position Effect ◽  
Upstream Region ◽  
Phosphorus Metabolism ◽  
Position Effects ◽  
Cis Acting ◽  
Independent Gene ◽  
Acting Mechanism

Abstract A transgenic position effect that causes activator-independent gene expression has been described previously for three Neurospora crassa phosphate-repressible genes. We report analogous findings for two additional positively regulated genes, qa-2  + and ars-1  +, indicating that such position effects are not limited to genes involved in phosphorus metabolism. In addition, we have characterized a number of mutants that display activator-independent gene expression. Each of these mutants contains a chromosomal rearrangement with one breakpoint located in the 5’-upstream region of the affected gene. This suggests that the rearrangements are associated with activator-independent gene expression and that these cis-acting mutations may represent a position effect similar to that responsible for rendering some transgenes independent of their transcriptional activators. We suggest that positively regulated genes in N.  crassa are normally held in a transcriptionally repressed state by a cis-acting mechanism until specifically activated. Disruption of this cis-acting mechanism, either by random integration of a gene by transformation or by chromosomal rearrangement, renders these genes independent or partly independent of the transcriptional activator on which they normally depend.

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