scholarly journals Transvection at the End of the Truncated Chromosome in Drosophila melanogaster

Genetics ◽  
2003 ◽  
Vol 163 (4) ◽  
pp. 1375-1387
Author(s):  
Mikhail Savitsky ◽  
Tatyana Kahn ◽  
Ekaterina Pomerantseva ◽  
Pavel Georgiev

Abstract The phenomenon of transvection is well known for the Drosophila yellow locus. Thus enhancers of a promoterless yellow locus in one homologous chromosome can activate the yellow promoter in the other chromosome where the enhancers are inactive or deleted. In this report, we examined the requirements for trans-activation of the yellow promoter at the end of the deficient chromosome. A number of truncated chromosomes ending in different areas of the yellow regulatory region were examined in combination with the promoterless y alleles. We found that trans-activation of the yellow promoter at the end of a deficient chromosome required ∼6 kb of an additional upstream sequence. The nature of upstream sequences affected the strength of transvection: addition of gypsy sequences induced stronger trans-activation than addition of HeT-A or yellow sequences. Only the promoter proximal region (within -158 bp of the yellow transcription start) was essential for trans-activation; i.e., transvection did not require extensive homology in the yellow upstream region. Finally, the yellow enhancers located on the two pairing chromosomes could cooperatively activate one yellow promoter.

2021 ◽  
Vol 30 (1) ◽  
pp. 95-103
Author(s):  
Mohammad Shamimul Alam ◽  
Israt Jahan ◽  
Sadniman Rahman ◽  
Hawa Jahan ◽  
Kaniz Fatema

Tilapia is a hardy fish which can survive in water bodies polluted with heavy metals. Metal resistance is conferred by higher expression of metallothionein gene (mt) in many organisms. Level, time and tissue-specificity of gene expression is regulated through transcription factor binding sites (TFBS) which may be present in the upstream, downstream, or even in the introns of a gene. So, as a candidate regulatory region, the 5’upstream sequence of mt gene in three tilapia species, Oreochromis aureus, O. niloticus and O. mossambicus was studied. The targeted region was PCR-amplified and then sequenced using a pair of custom-designed primer. A total of only 2.7% variation was found in the sequenced genomic region among the three species. Metal-related TFBS were predicted from these sequences. A total of twenty eight TFBS were found in O. aureus and twenty nine in O. mossambicus and O. niloticus. The number of metalrelated TFBS predicted in the targeted sequence was significantly higher compared to that found in randomly selected other genomic regions of same size from O. niloticus genome. Thus, the results suggest the presence of putative regulatory elements in the targeted upstream region which might have important role in the regulation of mt gene function. Dhaka Univ. J. Biol. Sci. 30(1): 95-103, 2021 (January)


Blood ◽  
1996 ◽  
Vol 88 (12) ◽  
pp. 4500-4509 ◽  
Author(s):  
KE Sahr ◽  
BP Daniels ◽  
M Hanspal

The AE1 gene is expressed in erythrocytes and the A-type intercalated cells of the kidney distal collecting duct. Although the 5′ end of the principal transcript expressed in murine erythroid cells has previously been mapped to a cluster of transcription start sites located immediately upstream of exon 1, the 5′ end of the mouse kidney transcript has not been identified. Using the anchored polymerase chain reaction technique to analyze mouse kidney AE1 mRNA, we identified an internal transcription start site located within erythroid intron 3. This site defines an exon of 37 nucleotides that forms the 5′ end of the mouse kidney AE1 transcript. AE1 transcripts beginning at this internal start site could not be detected in RNA isolated from purified erythroid progenitor cells or from erythroid cells undergoing erythropoietin-dependent terminal maturation, although transcripts derived from the upstream site were abundant, indicating that only the upstream promoter is active during erythropoiesis. Transient expression of reporter constructs in erythroid and nonerythroid cell lines identified a proximal upstream region of approximately 135 nucleotides that was active as a basal promoter. However, an additional approximately 200 nucleotides of upstream sequence was required for induced levels of activity in erythroid cells. Although our functional approach does not yet indicate the precise sequences required for erythroid induction, the AE1 gene upstream region contains potential GATA sites at -154, -141, and -60; an E-box at -163; CACCC or GGTGG motifs at -188, -121, and -88; and an AP-1/NF-E2-like site at -42.


1996 ◽  
Vol 16 (11) ◽  
pp. 6509-6515 ◽  
Author(s):  
T Murata ◽  
Y Kageyama ◽  
S Hirose ◽  
H Ueda

The transcription factor FTZ-F1 is a member of the nuclear hormone receptor superfamily and is transiently expressed during the mid- and late prepupal periods in Drosophila melanogaster. A putative pupal cuticle gene, EDG84A, is expressed slightly following FTZ-F1 expression during the prepupal period and carries a strong FTZ-F1 binding site between bases 100 and 92 upstream of its transcription start site. In this study, EDG84A mRNA was found to be prematurely expressed upon heat induction of FTZ-F1 in prepupae carrying the heat shock promoter-FTZ-F1 cDNA fusion gene construct. Transgenic fly lines having the 0.8-kb region of the EDG84A promoter fused to lacZ expressed the reporter gene in a tissue- and stage-specific manner. Base substitutions in the FTZ-F1 binding site within the 0.8-kb promoter abolished expression of lacZ. These results strongly suggest that the EDG84A gene is a direct target of FTZ-F1. Deletion studies of the cis-regulatory region of the EDG84A gene revealed that space-specific expression in imaginal disc-derived epidermis is controlled by the region between bp -408 and -104 from the transcription start site. The region between bp -408 and -194 is necessary to repress expression in a posterior part of the body, while the region between bp -193 and -104 carries a positive element for activation in an anterior part of the body. These results suggest that FTZ-F1 governs expression of the EDG84A gene in conjunction with putative tissue-specific regulators.


1997 ◽  
Vol 17 (7) ◽  
pp. 3799-3808 ◽  
Author(s):  
J A Weber ◽  
D J Taxman ◽  
Q Lu ◽  
D S Gilmour

GAGA factor, TFIID, and paused polymerase are present on the hsp70 promoter in Drosophila melanogaster prior to transcriptional activation. In order to investigate the interplay between these components, mutant constructs were analyzed after they had been transformed into flies on P elements. One construct lacked the TATA box and the other lacked the upstream regulatory region where GAGA factor binds. Transcription of each mutant during heat shock was at least 50-fold less than that of a normal promoter construct. Before and after heat shock, both mutant promoters were found to adopt a DNase I hypersensitive state that included the region downstream from the transcription start site. High-resolution analysis of the DNase I cutting pattern identified proteins that could be contributing to the hypersensitivity. GAGA factor footprints were clearly evident in the upstream region of the TATA deletion construct, and a partial footprint possibly caused by TFIID was evident on the TATA box of the upstream deletion construct. Permanganate treatment of intact salivary glands was used to further characterize each promoter construct. Paused polymerase and TFIID were readily detected on the normal promoter construct, whereas both deletions exhibited reduced levels of each of these factors. Hence both the TATA box and the upstream region are required to efficiently recruit TFIID and a paused polymerase to the promoter prior to transcriptional activation. In contrast, GAGA factor appears to be capable of binding and establishing a DNase I hypersensitive region in the absence of TFIID and polymerase. Interestingly, purified GAGA factor was found to bind near the transcription start site, and the strength of this interaction was increased by the presence of the upstream region. GAGA factor alone might be capable of establishing an open chromatin structure that encompasses the upstream regulatory region as well as the core promoter region, thus facilitating the binding of TFIID.


Genetics ◽  
1979 ◽  
Vol 92 (2) ◽  
pp. 485-502
Author(s):  
T K Johnson ◽  
B H Judd

ABSTRACT Mutants of the cut (ct) locus can be divided into two classes: viable and lethal. Most of the viable alleles are characterized by varying degrees of scalloping and notching of the wings. One mutant, kinked femur, exhibits kinking of the femurs and failure of wing expansion, but no other changes in wing structure. In heterozygous combination with the other viable alleles, it exhibits complete complementation, but it fails to complement with lethal ct alleles with respect to its viable phenotype. Similarly, all of the other viable ct alleles express a mutant wing phenotype when heterozygous with lethal ct alleles.—Mapping experiments indicate that the lethal alleles, which comprise the majority of all ct mutations recovered, are confined to a small region at the right end of the locus. That this restriction is real and not an artifact imposed by the limited number of lethal mutations mapped in the locus is supported by an examination of the mutant ctJC20, a presumptive deficiency for the left-most third of the locus. Despite its behavior as a deletion, ctJC20 is viable, though mutant, in combination with the lethal alleles. The restriction of the noncomplementary lethals to a small part of the locus, distinct from the other ct mutants, suggests a polarity that may define a segment that functions only in cis within the complex.—Based on the comparison of the data with the prediction of several models, we suggest that the left portion of the locus, which contains the viable alleles, defines a regulatory region controlling the expression of the locus, while the segment encoding a polypeptide product is at the right end and only it is capable of mutating to a lethal state.


Genetics ◽  
1990 ◽  
Vol 126 (1) ◽  
pp. 167-176
Author(s):  
D Gubb ◽  
M Ashburner ◽  
J Roote ◽  
T Davis

Abstract The zeste mutation of Drosophila melanogaster suppresses the expression of white genes in the eye. This suppression is normally dependent on there being two copies of w+ located close to each other in the genome--they may either be in cis (as in a tandem duplication of w+) or in trans, i.e. on homologous chromosomes. Duplicated w+ genes carried by a giant transposing element, TE146(Z), are suppressed by z whether they are in direct (tandem) or inverted order. The tandem form of the TE is very sensitive to a rearrangement on the homologous chromosome--many rearrangements with breakpoints "opposite" the TE's insertion site prevent the interaction between the white genes on a z background. These aberrations act as dominant suppressors of zeste that are specific to the tandemly duplicated form of TE146(Z). The inverted form of the TE146(Z) presumably pairs as a hairpin loop; this is more stable than the tandem form by the criterion that its zeste phenotype is unaffected by any of the aberrations. This effect of rearrangements has been used as the basis for a screen, gamma-ray induced aberrations with at least one breakpoint opposite the TE site were recovered by their suppression of the zeste phenotype.


Genetics ◽  
2001 ◽  
Vol 157 (2) ◽  
pp. 667-677
Author(s):  
Hitoshi Araki ◽  
Nobuyuki Inomata ◽  
Tsuneyuki Yamazaki

Abstract In this study, we randomly sampled Drosophila melanogaster from Japanese and Kenyan natural populations. We sequenced duplicated (proximal and distal) Amy gene regions to test whether the patterns of polymorphism were consistent with neutral molecular evolution. Fst between the two geographically distant populations, estimated from Amy gene regions, was 0.084, smaller than reported values for other loci, comparing African and Asian populations. Furthermore, little genetic differentiation was found at a microsatellite locus (DROYANETSB) in these samples (Gst′=−0.018). The results of several tests (Tajima's, Fu and Li's, and Wall's tests) were not significantly different from neutrality. However, a significantly higher level of fixed replacement substitutions was detected by a modified McDonald and Kreitman test for both populations. This indicates that positive selection occurred during or immediately after the speciation of D. melanogaster. Sliding-window analysis showed that the proximal region 1, a part of the proximal 5′ flanking region, was conserved between D. melanogaster and its sibling species, D. simulans. An HKA test was significant when the proximal region 1 was compared with the 5′ flanking region of Alcohol dehydrogenase (Adh), indicating a severe selective constraint on the Amy proximal region 1. These results suggest that natural selection has played an important role in the molecular evolution of Amy gene regions in D. melanogaster.


2006 ◽  
Vol 26 (16) ◽  
pp. 6094-6104 ◽  
Author(s):  
Masatoshi Aida ◽  
Yexi Chen ◽  
Koichi Nakajima ◽  
Yuki Yamaguchi ◽  
Tadashi Wada ◽  
...  

ABSTRACT Human 5,6-dichloro-1-β-d-ribofuranosylbenzimidazole sensitivity-inducing factor (DSIF) and negative elongation factor (NELF) negatively regulate transcription elongation by RNA polymerase II (RNAPII) in vitro. However, the physiological roles of this negative regulation are not well understood. Here, by using a number of approaches to identify protein-DNA interactions in vivo, we show that DSIF- and NELF-mediated transcriptional pausing has a dual function in regulating immediate-early expression of the human junB gene. Before induction by interleukin-6, RNAPII, DSIF, and NELF accumulate in the promoter-proximal region of junB, mainly at around position +50 from the transcription initiation site. After induction, the association of these proteins with the promoter-proximal region continues whereas RNAPII and DSIF are also found in the downstream regions. Depletion of a subunit of NELF by RNA interference enhances the junB mRNA level both before and after induction, indicating that DSIF- and NELF-mediated pausing contributes to the negative regulation of junB expression, not only by inducing RNAPII pausing before induction but also by attenuating transcription after induction. These regulatory mechanisms appear to be conserved in other immediate-early genes as well.


Genetics ◽  
1996 ◽  
Vol 143 (1) ◽  
pp. 353-364 ◽  
Author(s):  
Jerry A Coyne

Abstract Females of Drosophila melanogaster and its sibling species D. simulans have very different cuticular hydrocarbons, with the former bearing predominantly 7,11-heptacosadiene and the latter 7-tricosene. This difference contributes to reproductive isolation between the species. Genetic analysis shows that this difference maps to only the third chromosome, with the other three chromosomes having no apparent effect. The D. simulans alleles on the left arm of chromosome 3 are largely recessive, allowing us to search for the relevant regions using D. melanogaster deficiencies. At least four nonoverlapping regions of this arm have large effects on the hydrocarbon profile, implying that several genes on this arm are responsible for the species difference. Because the right arm of chromosome 3 also affects the hydrocarbon profile, a minimum of five genes appear to be involved. The large effect of the third chromosome on hydrocarbons has also been reported in the hybridization between D. simulans and its closer relative D. sechellia, implying either an evolutionaly convergence or the retention in D. sechllia of an ancestral sexual dimorphism.


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