| 1. |
- Dellino, Gaetano I, et al.
(författare)
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Polycomb silencing blocks transcription initiation.
- 2004
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Ingår i: Molecular Cell. - 1097-2765 .- 1097-4164. ; 13:6, s. 887-93
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Tidskriftsartikel (refereegranskat)abstract
- Polycomb (PcG) complexes maintain the silent state of target genes. The mechanism of silencing is not known but has been inferred to involve chromatin packaging to block the access of transcription factors. We have studied the effect of PcG silencing on the hsp26 heat shock promoter. While silencing does decrease the accessibility of some restriction enzyme sites to some extent, it does not prevent the binding of TBP, RNA polymerase, or the heat shock factor to the hsp26 promoter, as shown by chromatin immunoprecipitation. However, we find that in the repressed state, the RNA polymerase cannot initiate transcription. We conclude that, rather than altering chromatin structure to block accessibility, PcG silencing in this construct targets directly the activity of the transcriptional machinery at the promoter.
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| 2. |
- Demakov, Sergei, et al.
(författare)
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Molecular and genetic organization of Drosophila melanogaster polytene chromosomes : evidence for two types of interband regions
- 2004
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Ingår i: Genetica. - 0016-6707 .- 1573-6857. ; 122:3, s. 311-324
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Tidskriftsartikel (refereegranskat)abstract
- The 3A and 60E regions of Drosophila melanogaster polytene chromosomes containing inserted copies of the P[1ArB] transposon have been subjected to an electron microscopic (EM) analysis. We show that both inserts led to formation of new bands within the interband regions 3A4/A6 and 60E8-9/E10. This allowed us to clone DNA of these interbands. Their sequences, as well as those of DNA from other four interbands described earlier, have been analyzed. We have found that, with the exception of 60E8-9/E10 interband, all other five regions under study corresponded to 5' or 3' ends of genes. We have further obtained the evidence for 60E8-9/E10 interband to harbor the 'housekeeping' RpL19 gene, which is transcribed in many tissues, including salivary glands. Based upon the genetic heterogeneity of the interbands observed a revised model of polytene chromosome organization is discussed.
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| 3. |
- Schwartz, Yuri B, et al.
(författare)
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Molecular characterization of the singed wings locus of Drosophila melanogaster
- 2004
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Ingår i: BMC Genetics. - : Springer Science and Business Media LLC. - 1471-2156. ; 5, s. 15-
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Tidskriftsartikel (refereegranskat)abstract
- It is not entirely clear from the present molecular analysis how the SWI protein may function in the ecdysone induced cascade. Currently all predictions agree in that SWI is very unlikely to be a nuclear protein. Thus it probably exercises its control of "late" ecdysone genes indirectly. Apparently the genetic regulation of ecdysone signaling is much more complex then was previously anticipated.
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| 4. |
- Schwartz, Yuri B, et al.
(författare)
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Polycomb silencing mechanisms in Drosophila
- 2004
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Ingår i: Cold Spring Harbor Symposia on Quantitative Biology. - : Cold Spring Harbor Laboratory. - 0091-7451 .- 1943-4456. ; 69, s. 301-308
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Tidskriftsartikel (refereegranskat)
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| 5. |
- Schwartz, Yuri B, et al.
(författare)
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Polytene chromosome interband DNA is organized into nucleosomes
- 2001
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Ingår i: Molecular Genetics and Genomics. - : Springer Science and Business Media LLC. - 1617-4615 .- 1617-4623. ; 265:2, s. 311-315
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Tidskriftsartikel (refereegranskat)abstract
- The molecular basis that underlies the maintenance of polytene chromosome banding pattern remains unclear. To test the possibility that the decondensed state of interbands is provoked by the absence of nucleosomes, we have subjected chromatin from the previously defined 61C7/C8 interband to digestion with micrococcal nuclease. We have demonstrated that interband DNA forms nucleosomes both in salivary glands and in the bulk of larval tissues. This finding strongly suggests that the difference in compaction between DNA in polytene chromosome bands and interbands results from differences that appear at the higher levels of chromatin organization.
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