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The Sgs-7 and Sgs-8 glue genes at 68C are divergently transcribed and are separated by 475 bp. Fusion genes with Adh or lacZ coding sequences were constructed, and the expression of these genes, with different amounts of upstream sequences present, was tested by a transient expression procedure and by germ line transformation. A cis-acting element for both genes is located asymmetrically in the intergenic region between -211 and -43 bp relative to Sgs-7. It is required for correct expression of both genes. This element can confer the stage- and tissue-specific expression pattern of glue genes on a heterologous promoter. An 86-bp portion of the element, from -133 to -48 bp relative to Sgs-7, is shown to be capable of enhancing the expression of a truncated and therefore weakly expressed Sgs-3 fusion gene. Recently described common sequence motifs of glue gene regulatory elements (T. Todo, M. Roark, K. Vijay Raghavan, C. A. Mayeda, and E.M. Meyerowitz, Mol. Cell. Biol. 10:5991-6002, 1990) are located within this 86-bp region.  相似文献   

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The upstream region of the PSS gene contains three positive cis-acting elements, upstream activation sequences 1 and 2 (UAS1 and UAS2) and a TATA box. The 5' end of UAS1 occurs between positions -239 and -209, and that of UAS2 is between positions -172 and -164. UAS2 contains 5'-TTCACATG-3' as a core sequence at positions -161 to -154. Mutational analysis revealed that this octamer is responsible for the control of PSS expression by inositol and choline. The TATA box is located at positions -112 to -108. In addition, PSS contains a negative cis-acting sequence between UAS2 and the TATA box.  相似文献   

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The normal developmental expression of the Drosophila salivary gland secretion protein gene Sgs-3 requires the interaction of a distal and proximal regulatory element. A deletion/replacement analysis of the proximal promoter in stably transformed lines shows that induction of an Sgs-3/Adh fusion gene is normal if sequences from +10 to -50 are replaced by those of the hsp70 gene. Sequences between -98 and -50 are necessary for this expression but there is internal redundancy within this region as two distinct upstream sequences of 18 and 22 bp respectively are sufficient for stage- and tissue-specific expression, albeit at reduced levels. A point mutation at -53 eliminates the ecdysone-mediated repression of the Sgs-3 promoter at pupariation. We report mosaicisms of expression within the salivary gland for a number of stably transformed lines.  相似文献   

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A cis acting regulatory region has previously been identified 300-500 bp upstream of the Drosophila glue protein gene, Sgs-4. The functional capabilities of this region have now been examined by fusing it to the Drosophila Adh gene and determining the pattern of expression from the fused construct after transformation. The results show that the Sgs-4 sequences between −150 and −568 are able to direct Adh expression in late third-instar salivary glands, the appropriate tissue and timing for Sgs-4 expression. In addition, the Sgs-4 sequence elevates Adh expression in the anterior midgut and fat body, despite the fact that Sgs-4 is not normally expressed there. All three regulatory activities, tissue specificity, timing and enhancement, show the positional flexibility of enhancer elements. In addition, the Sgs-4 and Adh regulatory elements combine to direct expression in novel spatial/temporal combinations in which neither would normally be expressed.  相似文献   

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Cooperative enhancement at the Drosophila Sgs-3 locus   总被引:4,自引:0,他引:4  
The Drosophila glue gene Sgs-3 is specifically expressed in the secretory cells of the salivary glands of third instar larvae. We have assayed the expression of gene fusions to determine the role of cis-acting Sgs-3 sequences in conferring this pattern of expression. These experiments define two regulatory regions required for expression of reporter genes from the Sgs-3 promoter. One region, between 106 and 56 bp upstream of the Sgs-3 mRNA 5' end is sufficient for low but correct tissue- and stage-specific expression. A second region, lying between 629 and 130 bp 5' of the RNA start site is functionally equivalent; that is, it alone will also direct low level, specific expression. These two regions act synergistically to give high level expression. More distant upstream regions function to further increase levels of expression. These two regulatory elements can confer a salivary gland-specific pattern of expression on a heterologous promoter and are also sufficient to drive gene expression in other Drosophila species, implying conservation of regulators.  相似文献   

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Pig-1 and Sgs-4 are a pair of closely linked and divergently transcribed Drosophila melanogaster genes, which are both expressed in larval salivary glands but at different times during development. While Sgs-4 is expressed at high levels only at the end of the third instar, Pig-1 exhibits a major peak of expression during late second and early third instar. Thus, Pig-1 expression declines as Sgs-4 expression is induced. In this paper, we show that three adjacent elements located within the short region between these genes can account for the switch from Pig-1 to Sgs-4 expression. A 170-bp segment acts as an enhancer to direct Sgs-4 expression in late-third-instar salivary glands. A 64-bp sequence located just upstream from the enhancer can modify its temporal specificity so that it works throughout the third instar. Expression induced at mid-third instar by a combination of these two elements can be repressed by a negative regulatory sequence located still further upstream. We present evidence suggesting that the changing interactions between these regulatory elements and the Sgs-4 and Pig-1 promoters lead to the correct pattern of expression of the two genes.  相似文献   

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Genes that encode 3rd instar larval cuticle proteins (LCP's) of Drosophila melanogaster are located in at least two chromosomal sites. The genes encoding four of the five predominant LCP's are located in a cluster at the chromosomal region 44D. They are organized in pairs that are transcribed divergently, and expressed with different timing during the third larval instar. Towards understanding the basis of gene regulation within the 44D cluster, we have analyzed genetic variants, including the 2-3 variant, which has an insertion of a copia-like transposable element, H.M.S. Beagle, within the 44D cluster. The Beagle element appears to inactivate the LCP-3 gene by inserting into its TATA box, but also may cause the precocious expression of two other LCP genes, LCP-1 and LCP-f2, in the cluster. The long terminal repeat (LTR) of the Beagle element apparently contains a sequence, perhaps an enhancer-like element, which causes altered expression of these genes. We have also investigated the cis-regulatory elements involved in expression of the LCP-2 gene in wild-type larvae. We have identified two upstream regions that may contain separate cis-regulatory elements. The region between -252 bp and -515 bp may be essential for any expression of LCP-2. Additionally, the region between -515 bp and -795 bp appears to be required for the normal level of expression of the LCP-2 gene.  相似文献   

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The Sgs-4 glue protein gene of Drosophila is expressed only in third-instar larval salivary glands. Previous work suggests that a regulatory region lies 5' and remote to the gene, as indicated by a region of tissue-specific DNase I hypersensitivity and by underproducing mutants with DNA lesions in the hypersensitive region. Here we demonstrate by germ line transformation of cloned fragments containing Sgs-4 that the sequences between 840 bp 5' and 130 bp 3' to the gene are sufficient for Sgs-4 activity. When 5' sequence was removed to -392, activity was eliminated, thereby verifying the existence of essential sequences far upstream. Fragments that are active include, in addition to the capacity for normal levels of expression, three other cis-acting regulatory activities: developmental timing, tissue specificity, and dosage compensation. In contrast, the fragments tested did not specify formation of the puff with which Sgs-4 is normally associated. As shown by chromosomal rearrangements, the region required for puffing is limited to 16-19 kb surrounding the gene.  相似文献   

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J Sheen 《The Plant cell》1991,3(3):225-245
I describe here the organization of maize C4 chloroplast and non-C4 cytosolic pyruvate, orthophosphate dikinase (PPDK) genes and the molecular mechanisms underlying their differential expression. The maize C4 chloroplast PPDK gene (C4ppdkZm1) appears to have been created by the addition of an exon encoding the chloroplast transit peptide at a site upstream of a cytosolic PPDK gene (cyppdkZm1). A splice acceptor sequence located in the first exon of cyppdkZm1 allows the fusion of the transit peptide to the cyppdkZm1 sequences. A second cyPPDK gene (cyppdkZm2) shares extensive homology with cyppdkZm1 in the coding region and in the 5' flanking region up to the TATA box. By a novel protoplast transient expression method, I show that the light-inducible expression of C4ppdkZm1 is controlled by two expression programs mediated through separate upstream regulatory elements that are active in leaf, but inactive in root and stem. Light-mediated C4ppdkZm1 expression in maize is apparently uncoupled from leaf development and partially associated with chloroplast development. For cyppdkZm1 expression, distinct upstream elements and a specific TATA promoter element, located in the first intron of C4ppdkZm1, are required. The low expression of cyppdkZm2 can be attributed to an absence of upstream positive elements and weak activity of the TATA promoter element.  相似文献   

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