Homology of Balbiani rings among chironomid species and localization of a new mobile element on the polytene chromosomes

1992 ◽  
Vol 26 (2-4) ◽  
pp. 123-128 ◽  
Author(s):  
M. A. Filippova ◽  
I. I. Kiknadze ◽  
K. G. Aimanova ◽  
J. Fischer ◽  
A. G. Blinov
Keyword(s):  
Polytene Chromosomes ◽  
Mobile Element ◽  
Chironomid Species ◽  
Balbiani Rings

FINE STRUCTURE OF NUCLEOLI AND RNA-CONTAINING CHROMOSOME REGIONS OF SALIVARY GLAND CHROMOSOMES OF CHIRONOMIDS AND THEIR INTERRELATIONSHIP

1964 ◽  
Vol 42 (6) ◽  
pp. 1147-1155 ◽  
Author(s):  
V. I. Kalnins ◽  
H. F. Stich ◽  
S. A. Bencosme
Keyword(s):  
Fine Structure ◽  
Salivary Gland ◽  
Electron Microscope ◽  
Light Microscopy ◽  
Messenger Rna ◽  
Balbiani Ring ◽  
Electron Microscopic ◽  
Chironomid Species ◽  
Balbiani Rings ◽  
Chromosome Regions

Electron microscope studies of salivary gland nuclei of four chironomid species have shown that the RNA-containing chromosome regions and associated structures, which by light microscopy exhibit a great variety of structures such as bands, granules, micronucleoli, nucleoli, puffs, and Balbiani rings, consist of only few basic units: pars amorpha, nucleolonema, and Balbiani ring granules. The fine structure of the nucleoli and spherical micronucleoli located at various chromosome regions appears to be identical, consisting of pars amorpha, which contains fibers of varying diameters, and strands of nucleolonema composed of fibers and ribosome-like granules. The arrangement of pars amorpha and nucleolonema of nucleoli and spherical micronucleoli follows a consistent pattern. Chromosome fibers are closely associated with pars amorpha, whereas strands of nucleolonema border only the surfaces of pars amorpha. Balbiani ring granules, which have a diameter of 300 Å to 500 Å and are characterized by a particular structure, accumulate in Balbiani rings, in many chromosome regions, and in nuclear sap. In the Balbiani ring these granules seem to be attached to 100 Å chromosome fibers. They are absent in nucleoli and micronucleoli. The possible correlation between our electron microscopic observations and the present-day concept of ribosomal and messenger RNA production is discussed.

scholarly journals Balbiani ring hnRNP substructure visualized by selective staining and electron spectroscopic imaging.

1992 ◽  
Vol 117 (3) ◽  
pp. 483-491 ◽  
Author(s):  
A L Olins ◽  
D E Olins ◽  
D P Bazett-Jones
Keyword(s):  
Nucleic Acid ◽  
Polytene Chromosomes ◽  
Particle Diameter ◽  
Balbiani Ring ◽  
Electron Spectroscopic Imaging ◽  
Selective Staining ◽  
Elemental Imaging ◽  
Mature Transcript ◽  
Balbiani Rings ◽  
Relationship Of

The Balbiani Rings (BR) in the polytene chromosomes of Chironomus salivary glands are intense sites of transcription. The nascent RNPs fold during transcription into 40-50-nm granules, containing in the mature transcript approximately 37-kb RNA. Using a new nucleic acid specific stain, osmium ammine B on Lowicryl sections, in combination with electron energy filtered imaging of sections containing BR granules, we demonstrate a RNA-rich particulate substructure (10-nm particle diameter; 10-12 particles per BR granule). Elemental imaging supports that these particles are enriched in phosphorus. The possible relationship of these RNA-rich particles to ribonucleosomes is discussed, as well as models for their arrangement in the mature BR granules.

Balbiani rings and puffs of the polytene chromosomes of Drosophila auraria

Chromosoma ◽  
1984 ◽  
Vol 89 (2) ◽  
pp. 96-106 ◽  
Author(s):  
Zacharias G. Scouras ◽  
Costas D. Kastritsis
Keyword(s):  
Polytene Chromosomes ◽  
Balbiani Rings

Cytotaxonomic differentiation of the Afrotropical Drosophila montium subgroup: D. diplacantha and D. seguyi. The major role of reverse tandem duplications

Genome ◽  
1994 ◽  
Vol 37 (6) ◽  
pp. 935-944 ◽  
Author(s):  
P. Mavragani-Tsipidou ◽  
A. Zambetaki ◽  
K. Kleanthous ◽  
E. Pangou ◽  
Z. G. Scouras
Keyword(s):  
Polytene Chromosomes ◽  
Balbiani Ring ◽  
Developmental Profile ◽  
Intraspecific Polymorphism ◽  
Balbiani Rings ◽  
Chromosome Maps ◽  
Temporal And Spatial ◽  
Montium Subgroup ◽  
Tandem Duplications

Aiming to establish phylogenetic relationships among species of the montium subgroup, detailed polytene chromosome maps are given showing intraspecific polymorphism and ecdysone induced larval puffing pattern profiles of two Afrotropical members of this subgroup, Drosophila diplacantha and D. seguyi. Both species exhibit two unique characteristics that define the montium subgroup, namely, a large number of reverse tandem duplications and a progressive darkening of anterior spiracles of the late third instar larvae, which is accompanied by a definite temporal and spatial puffing pattern of the salivary gland chromosomes. In contrast with the well-formed Balbiani ring 1 (BR1) observed in Oriental and Indian montium species, BR1 exhibits a different developmental profile in D. diplacantha, while it is obscured in D. seguyi. Although phyletic comparisons of five species from five different complexes within the subgroup show some conservation in banding and puffing pattern homologies, an analysis to assign map sections by sequential rearrangements remains unresolved at this time. The evolution of the subgroup is discussed in relation with the sharing of reverse tandem duplications, especially those including the montium BRs.Key words: Drosophila montium, polytene chromosomes, Balbiani rings, puffs, duplications, inversions.

Ultrastructural Studies of Isolated Polytene Chromosomes by Scanning Electron Microscopy

1976 ◽  
Vol 34 ◽  
pp. 196-197
Author(s):  
Michael B. Payne
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Polytene Chromosomes ◽  
Mitotic Chromosomes ◽  
Characteristic Appearance ◽  
Ultrastructural Studies ◽  
Transmission Electron ◽  
Balbiani Rings ◽  
Chromatin Fibers ◽  
Scanning Electron

Scanning and transmission electron microscopy studies of mitotic chromosomes have demonstrated that these chromosomes are composed of single intricately coiled and folded chromatin fibers 200-300 A in diameter (1). Transmission electron microscopy studies (2) have shown similar fibers in dipteran polytene chromosomes. It has been proposed that these fibers are extended in the less densely appearing interband regions and become more tightly coiled or folded at specific sites to produce the densely appearing banded regions (3). With the scanning electron microscope it is now possible to observe the characteristic appearance of the chromatin fibers in the band and interband regions of isolated intact polytene chromosomes. Furthermore, the morphology of the nucleolus and Balbiani rings can be observed as specialized structures in the chromosome.

scholarly journals Inherited and somatic cytogenetic variability in Palearctic populations of Chironomus riparius Meigen 1804 (Diptera, Chironomidae)

Genome ◽  
2004 ◽  
Vol 47 (2) ◽  
pp. 332-344 ◽  
Author(s):  
Gabriella Sella ◽  
Stefano Bovero ◽  
Marco Ginepro ◽  
Paraskeva Michailova ◽  
Ninel Petrova ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Metal Pollution ◽  
Heavy Metal Pollution ◽  
Polytene Chromosomes ◽  
Chironomus Riparius ◽  
Heterozygous State ◽  
Chironomid Species ◽  
Different Types ◽  
Chironomus Thummi ◽  
Somatic Aberrations

Inter- and intracytogenetic variability was analyzed in 13 natural Palearctic populations of Chironomus riparius Meigen 1804 (syn. Chironomus thummi) by examining hereditary and somatic aberrations (mainly inversions) of the salivary gland polytene chromosomes. In total, 77 different types of inherited inversion sequences and 184 different types of somatic inversions were found. The median percent frequency of inherited inversions was 1.4% and karyotypic divergence between populations was very low. Most hereditary inversions were endemic and always in a heterozygous state. Only six inversion sequences, each of them shared by two very distant populations, may be considered a relic of very ancient ancestral inversions. Unlike inherited inversions, occurrence of somatic aberrations seems to increase with the overall rise in the level of heavy metal pollution of the sediments from which larvae were sampled. In contrast with what occurs in populations of other chironomid species, populations of C. riparius do not seem to undergo a process of cytogenetic differentiation.Key words: Chironomus thummi, polytene chromosomes, inversion polymorphism, somatic aberrations, heavy metal pollution.

scholarly journals Analysis of Two Cosmid Clones from Chromosome 4 of Drosophila melanogaster Reveals Two New Genes Amid an Unusual Arrangement of Repeated Sequences

1999 ◽  
Vol 9 (2) ◽  
pp. 137-149 ◽  
Author(s):  
John Locke ◽  
Lynn Podemski ◽  
Ken Roy ◽  
David Pilgrim ◽  
Ross Hodgetts
Keyword(s):  
Drosophila Melanogaster ◽  
Dna Sequences ◽  
Polytene Chromosomes ◽  
Mobile Element ◽  
The Other ◽  
P Element ◽  
Matrix Analysis ◽  
Predicted Amino Acid Sequence ◽  
Chromosome 4 ◽  
New Genes

Chromosome 4 from Drosophila melanogaster has several unusual features that distinguish it from the other chromosomes. These include a diffuse appearance in salivary gland polytene chromosomes, an absence of recombination, and the variegated expression of P-element transgenes. As part of a larger project to understand these properties, we are assembling a physical map of this chromosome. Here we report the sequence of two cosmids representing ∼5% of the polytenized region. Both cosmid clones contain numerous repeated DNA sequences, as identified by cross hybridization with labeled genomic DNA, BLAST searches, and dot matrix analysis, which are positioned between and within the transcribed sequences. The repetitive sequences include three copies of the mobile element Hoppel, one copy of the mobile element HB, and 18 DINE repeats. DINE is a novel, short repeated sequence dispersed throughout both cosmid sequences. One cosmid includes the previously described cubitus interruptus(ci) gene and two new genes: that a gene with a predicted amino acid sequence similar to ribosomal protein S3a which is consistent with the Minute(4)101 locus thought to be in the region, and a novel member of the protein family that includes plexin and met–hepatocyte growth factor receptor. The other cosmid contains only the two short 5′-most exons from thezinc-finger-homolog-2 (zfh-2) gene. This is the first extensive sequence analysis of noncoding DNA from chromosome 4. The distribution of the various repeats suggests its organization is similar to the β-heterochromatic regions near the base of the major chromosome arms. Such a pattern may account for the diffuse banding of the polytene chromosome 4 and the variegation of many P-element transgenes on the chromosome.

scholarly journals SUMM4 complex couples insulator function and DNA replication timing control

2021 ◽  
Author(s):  
Evgeniya N. Andreyeva ◽  
Alexander V. Emelyanov ◽  
Markus Nevil ◽  
Lu Sun ◽  
Elena Vershilova ◽  
...  
Keyword(s):  
Dna Replication ◽  
Critical Role ◽  
Regulation Of Gene Expression ◽  
Polytene Chromosomes ◽  
Mobile Element ◽  
Replication Timing ◽  
Related Factor ◽  
Timing Control

AbstractThe asynchronous timing of replication of different chromosome domains is essential for eukaryotic genome stability, but the mechanisms establishing replication timing programs remain incompletely understood. Drosophila SNF2-related factor SUUR imparts under- replication (UR) of late-replicating intercalary heterochromatin (IH) domains in polytene chromosomes1. SUUR negatively regulates DNA replication fork progression across IH; however, its mechanism of action remains obscure2, 3. Here we developed a novel method termed MS-Enabled Rapid protein Complex Identification (MERCI) to isolate a stable stoichiometric native complex SUMM4 that comprises SUUR and a chromatin boundary protein Mod(Mdg4)- 67.24, 5. In vitro, Mod(Mdg4) stimulates the ATPase activity of SUUR, although neither SUUR nor SUMM4 can remodel nucleosomes. Mod(Mdg4)-67.2 and SUUR distribution patterns in vivo partially overlap, and Mod(Mdg4) is required for a normal spatiotemporal distribution of SUUR in chromosomes. SUUR and Mod(Mdg4)-67.2 mediate insulator activities of the gypsy mobile element that disrupt enhancer-promoter interactions and establish euchromatin- heterochromatin barriers in the genome. Furthermore, mutations of SuUR or mod(mdg4) reverse the locus-specific UR. These findings reveal that DNA replication can be delayed by a chromatin barrier and thus, uncover a critical role for architectural proteins in replication timing control. They also provide a biochemical link between ATP-dependent motor factors and the activity of insulators in regulation of gene expression and chromatin partitioning.

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