Effect of salt-treatment on manually isolated polytene chromosomes from Chironomus tentans

Chromosoma ◽  
1978 ◽  
Vol 68 (1) ◽  
pp. 1-19 ◽  
Author(s):  
Ulrich Plagens
Keyword(s):  
Polytene Chromosomes ◽  
Chironomus Tentans ◽  
Salt Treatment

Inactive chromatin in polytene chromosomes of Chironomus tentans partially shows a non-nucleosomal organization

Chromosoma ◽  
1986 ◽  
Vol 94 (1) ◽  
pp. 19-30 ◽  
Author(s):  
Endre Egyh�zi ◽  
Johan Thyberg ◽  
Andrew Pigon ◽  
Olle Johansson
Keyword(s):  
Polytene Chromosomes ◽  
Chironomus Tentans ◽  
Inactive Chromatin

Divergent cytogenetic evolution in Nearctic and Palearctic populations of sibling species in Chironomus (Camptochironomus) Kieffer

1998 ◽  
Vol 76 (2) ◽  
pp. 361-376
Author(s):  
Iya I Kiknadze ◽  
Malcolm G Butler ◽  
Karlygash G Aimanova ◽  
Evgenya N Andreeva ◽  
Jon Martin ◽  
...  
Keyword(s):  
Sibling Species ◽  
Related Species ◽  
Polytene Chromosomes ◽  
Natural Populations ◽  
Chromosomal Polymorphism ◽  
The Other ◽  
Chironomus Tentans ◽  
Closely Related Species ◽  
Cytogenetic Evolution

Chromosomal polymorphism is described for natural populations of Chironomus pallidivittatus in both the Palearctic and Nearctic regions. The Palearctic populations studied exhibit 24 banding sequences, whereas 10 banding sequences have been recorded from Nearctic C. pallidivittatus. In total, 29 sequences and 37 genotypic combinations have been found. Of the 29 sequences known, only 5 are Holarctic (common to both the Nearctic and Palearctic), 19 are exclusively Palearctic, and 5 are Nearctic. The karyotype of Nearctic C. pallidivittatus is characterized by specific, homozygous Nearctic sequences in arms B and G and fixed Holarctic inversion sequences in the other arms. Only two chromosome arms in C. pallidivittatus, but all seven arms in the sibling species Chironomus tentans, differ between Palearctic and Nearctic forms by the presence of unique, homozygous sequences in the Nearctic karyotype. This indicates a great difference in the cytogenetic histories of these closely related species; much less karyotypic divergence between continents has occurred in C. pallidivittatus than in C. tentans. The cytogenetic distance between Palearctic and Nearctic populations of C. tentans is higher (DN = 1.62) than in C. pallidivittatus (DN = 0.27). Thus, Palearctic and Nearctic C. tentans should be regarded as sibling species, but Palearctic and NearcticC. pallidivittatus are best viewed as strongly divergent races of the same species. A photomap of polytene chromosomes of C. pallidivittatus is presented in which banding sequences are mapped by using C. tentans as a standard.

Energy-filtered STEM imaging of thick biological sections

1988 ◽  
Vol 46 ◽  
pp. 526-527
Author(s):  
C. Colliex ◽  
C. Mory ◽  
A. L. Olins ◽  
D. E. Olins ◽  
M. Tencé
Keyword(s):  
Salivary Gland ◽  
Standard Deviation ◽  
Energy Loss ◽  
Quantitative Study ◽  
Polytene Chromosomes ◽  
Physical Parameters ◽  
Chironomus Tentans ◽  
Bright Field ◽  
The Mean

Energy filtered imaging of thick biological specimens offers an excellent alternative to HVEM or IVEM. In order to explore the physical parameters which effect the energy loss spectra and the images formed by various energy loss windows we undertook a quantitative study using a dedicated STEM (VG-HB501) fitted with an energy loss spectrometer and interfaced with sophisticated data acquisition capability. Our mathematical analysis is useful in predicting the quality of bright field thick specimen images formed with energy filtered electrons.Our specimen was the salivary gland of Chironomus tentans which contains giant polytene chromosomes. Conventional preparative methods included fixation, epon embedding, and cutting 0.5 μm sections. Digital images were formed at plasomon (∼25 eV) multiples (n = 0 to 7). For each image the mean (I), maximum and minimum intensities and the standard deviation (σ) were determined.

The 3-D substructure of RNA in nascent RNP granules: A novel application of osmium ammine-B staining and electron spectroscopic imaging

1992 ◽  
Vol 50 (1) ◽  
pp. 504-505
Author(s):  
Ada L. Olins ◽  
Donald E. Olins ◽  
Manesh B. Shah ◽  
Henri A. Levy ◽  
David P. Bazett-Jonest
Keyword(s):  
Salivary Gland ◽  
Polytene Chromosomes ◽  
Spectroscopic Imaging ◽  
Secretory Proteins ◽  
Chironomus Tentans ◽  
Balbiani Ring ◽  
Electron Spectroscopic Imaging ◽  
Nuclear Pores ◽  
Rnp Granules

RNA has a particulate substructure when visualized in situ with the nucleic acid specific stain osmium ammine-B (OA-B). In this study energy spectroscopic imaging (ESI) was used to enhance the contrast and collect the data for tomographic reconstructions.The Balbiani ring (BR) in the salivary gland polytene chromosomes of Chironomus tentans larvae furnishes a well known model for the structure of nascent m-RNA. This gland produces copious amounts of silk-like secretory proteins which are very large (106 daltons). The site of transcription, the BR, is easily recognized in the EM by its characteristic “puff” structure and electron-dense granular transcripts. Mature BR granules are 45-50 nm in diameter and can be easily observed within the nucleus and passing through nuclear pores.

Chromosomal RNA synthesis in polytene chromosomes of Chironomus tentans

Chromosoma ◽  
1969 ◽  
Vol 28 (4) ◽  
Author(s):  
B. Daneholt ◽  
J.-E. Edstr�m ◽  
E. Egyh�zi ◽  
B. Lambert ◽  
U. Ringborg
Keyword(s):  
Rna Synthesis ◽  
Polytene Chromosomes ◽  
Chironomus Tentans

Physico-chemical properties of chromosomal RNA in Chironomus tentans polytene chromosomes

Chromosoma ◽  
1969 ◽  
Vol 28 (4) ◽  
Author(s):  
B. Daneholt ◽  
J.-E. Edstr�m ◽  
E. Egyh�zi ◽  
B. Lambert ◽  
U. Ringborg
Keyword(s):  
Polytene Chromosomes ◽  
Chemical Properties ◽  
Chironomus Tentans ◽  
Physico Chemical
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