Electron microscopy of an induced “lampbrush stage” of the polytene chromosome

Sorsa, Veikko; Pusa, K.; Virrankoski, Virpi; Sorsa, Marja

doi:10.1016/0014-4827(70)90546-x

Cited by 20 publications

(2 citation statements)

References 3 publications

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“…I should like to propose that if such a tight type of helical organization as proposed by FINCH and KLUG or by ALBERTS et al does exist in the salivary gland chromosome bands, it may consist of some units smaller than chrornomeres, probably of the replicative units. This view may already have gained strong support in the results of earlier experimental studies on the salivary gland chromosomes (SORSA 1971(SORSA , 1973(SORSA , 1974, which indicate the existence of a rather small, globular type of chromatin units.…”

Section: Hairpin Loop Models Of Chromomere Structurementioning

confidence: 73%

Beaded organization of chromatin in the salivary gland chromosome bands of Drosophila melanogaster

Sorsa

2009

Hereditas

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Beads on a string type of organization were found in chromomeric fibrils by electron microscopic studies on thin‐sectioned polytene chromosomes of Drosophila melanogaster. The beaded fibrils occur parallelly and are probably supercoiled pairs. In certain small bands the orientation of paired fibrils is clearly transversal to the longitudinal axis of the chromosome. The transverse position and some hairpin‐like ends of paired fibrils point to the cruciform palindromes or closed loop type or chromomere organization in these bands. In larger bands the coiling organization of chromomeric fibrils is more complicated. Some hypothetical models for the uni‐ and multireplicon type of chromomeres are presented. The obvious branching of chromomeric fibrils at the border region of certain hands indicates a local polyteny in these bands.

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Section: Hairpin Loop Models Of Chromomere Structurementioning

confidence: 73%

Beaded organization of chromatin in the salivary gland chromosome bands of Drosophila melanogaster

Sorsa

2009

Hereditas

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“…The description of the induced "lampbrush stage" in the giant polytene chromosomes date from many years ago (Sorsa et al 1970). This effect was possible with urea-alkali treatment of the Drosophila polytene nucleus.…”

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confidence: 99%

Drosophila Salivary Gland Polytene Nuclear Halo: A New Approach for Polytene Nuclear Matrix Analysis.

et al. 2001

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This work presents a procedure to perform nuclear halos, nuclear matrix with the associated DNA loops, from Drosophila salivary gland polytene nucleus. The purification with hypo-osmotic buffers in the absence of polyamines, as spermine and spermidine, whose function seems to be related to the chromatin compaction, was considered essential. The non-compacted polytene chromosome in the giant nucleus could be used for protein extraction that allows the liberation of the loops. The profile of the DNA matrix and loop fractions, left after nuclear halo digestion with restriction enzyme, confirms the relationship between these fractions suitable for functional analysis. This procedure could be important to obtain a direct relationship between nuclear matrix association and transcription process in the interphase polytene chromosomes of Drosophila salivary gland nucleus.

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Electron Microscopic Mapping and Ultrastructure of Drosophila Polytene Chromosomes

Sorsa

1984

Insect Ultrastructure

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Electron microscopy of an induced “lampbrush stage” of the polytene chromosome

Cited by 20 publications

References 3 publications

Beaded organization of chromatin in the salivary gland chromosome bands of Drosophila melanogaster

Beaded organization of chromatin in the salivary gland chromosome bands of Drosophila melanogaster

Drosophila Salivary Gland Polytene Nuclear Halo: A New Approach for Polytene Nuclear Matrix Analysis.

Electron Microscopic Mapping and Ultrastructure of Drosophila Polytene Chromosomes

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