Electron Microscopic Mapping and Ultrastructure of Drosophila Polytene Chromosomes

Sorsa, Veikko

doi:10.1007/978-1-4613-2715-8_3

Cited by 16 publications

(11 citation statements)

References 83 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Thus, the results obtained by analyzing the constructs with transcriptionally active and silent interbands do not support the hypothesis on the existence of distinct cytogenetic ''band + interband'' units (Crick 1971;Sorsa 1984). These data suggest that interbands display inherent autonomy as morphological structures, which might explain the high reproducibility of the banding pattern in polytene chromosomes.…”

Section: Discussioncontrasting

confidence: 72%

“…According to different estimates, the sizes of the interbands vary between 0.05 and 0.38 lm, most frequently being 0.1-0.2 lm, and their molecular sizes are 0.3-3.8 kb (Beermann 1972;Sorsa 1984;Zhimulev 1996). Reliable mapping of ''genuine'' interbands is possible only with high-resolution techniques like electron microscopy (EM) ).…”

Section: Introductionmentioning

confidence: 98%

“…For instance, the coding DNA sequences are hypothesized to be situated in the interbands and respective control elements occupy the adjacent band (Crick 1971). Alternatively, the interband is thought to contain regulatory region with ''address sites'' for RNA polymerase II binding, and the band encompasses the very transcribed sequence (Paul 1972;Sorsa 1984). Antibodies against dCHDl (chromoATPase/helicase-DNA-binding protein), tandem kinase JIL-1, Brahma, and modified histones localize these proteins to interbands (reviewed in: Zhimulev et al 2004).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Interbands behave as decompacted autonomous units in Drosophila melanogaster polytene chromosomes

et al. 2007

View full text Add to dashboard Cite

We studied whether interbands can be ectopically formed in Drosophila melanogaster polytene chromosomes. For comparative purposes, two types of P-element constructs were used. The first type was represented by P-element based insertions into compact bands. Sequences of these insertions or adjacent genomic sequences could be activated ectopically either by GAL4 or by dosage compensation machinery. In the second type, the DNA from transcriptionally silent interbands was positioned between the FRT sites, and was flanked by DNA sequences of genes that were also inactive in salivary glands. Electron microscopy analysis of salivary gland polytene chromosomes demonstrated that both types of constructs formed distinct, yet morphologically similar interbands. Notably, the second class of transposon insertions appeared in polytene chromosomes as two bands separated by one interband. Excision of interband material from such insertions resulted in fusion of newly appeared bands into a single band. We were able to confirm by molecular means that the DNA sequences in integrated constructs were intact, that chromatin organization of this DNA mimicked that of native interbands, and that it was accurately excised from the constructs by FLP. Thus, we demonstrate that transfer of interband DNA into a silent genetic environment does not compromise interband formation. Our results do not support the idea of the existence of distinct cytogenetic "band + interband" units, furthermore, they suggest the autonomy of the decompacted state of interbands.

show abstract

Section: Discussioncontrasting

confidence: 72%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Interbands behave as decompacted autonomous units in Drosophila melanogaster polytene chromosomes

et al. 2007

View full text Add to dashboard Cite

show abstract

“…However, the functional organization of interbands and the nature of banding pattern in general still remain enigmatic. According to different estimates, the size of interband DNA ranges in length from 0.5 to 3.8 kb and it constitutes about 5% of euchromatic DNA (Beermann, 1972;Sorsa, 1984;for review: Zhimulev, 1996). Features of interbands such as localization of RNA polymerase II (Jamrich, Greenleaf & Bautz, 1977;Sass & Bautz, 1982), incorporation of [ 3 H] uridine (Semeshin, Zhimulev & Belyaeva, 1979), presence of DNA:RNA hybrids (Vlassova et al, 1985) and products of transcription -RNP granules (Skaer, 1977;Mott & Hill, 1986) -led to a widely accepted hypothesis that interbands contain permanently transcribed 'housekeeping' genes (Gersh, 1975;Zhimulev & Belyaeva, 1975).…”

Section: Introductionmentioning

confidence: 99%

Molecular and genetic organization of Drosophila melanogasterpolytene chromosomes: evidence for two types of interband regions

et al. 2004

View full text Add to dashboard Cite

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.

show abstract

“…The structural features of these regions, containing both band and interband material, may have been ascribed to interbands. On the other hand the 5-nm nucleosome free interband ®brils reported by Sorsa (1982Sorsa ( , 1984 are also not conclusive (in this case EM thin sections of third-instar larval salivary gland polytene chromosomes were ®xed in 4% formaldehyde and squashed in 45% acetic acid). Although in these particular experiments correspondence between the regions examined and the Bridges map was well established, indicating that``true interbands'' had been examined, it seems strange that Sorsa (1984) observed bands that were composed mainly of 12-nm ®brils, in spite of 30-nm nucleomere ®brils were also clearly visible in these preparations.…”

Section: Introductionmentioning

confidence: 92%

Polytene chromosome interband DNA is organized into nucleosomes

2001

View full text Add to dashboard Cite

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.

show abstract

Electron Microscopic Mapping and Ultrastructure of Drosophila Polytene Chromosomes

Cited by 16 publications

References 83 publications

Interbands behave as decompacted autonomous units in Drosophila melanogaster polytene chromosomes

Interbands behave as decompacted autonomous units in Drosophila melanogaster polytene chromosomes

Molecular and genetic organization of Drosophila melanogasterpolytene chromosomes: evidence for two types of interband regions

Polytene chromosome interband DNA is organized into nucleosomes

Contact Info

Product

Resources

About