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  • 1
    Electronic Resource
    Electronic Resource
    Evolutionary conservation of the 3′ ends of members of a family of giant secretory protein genes inChironomus pallidivittatus (1987)
    Springer
    Journal of molecular evolution 25 (1987), S. 20-28 
    Details
    ISSN: 1432-1432
    Keywords: Balbiani rings ; Evolution ; Immunological detection ; Nucleotide sequence ; 3′ End
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two cDNA clones representing the 3′-end regions of BR1 and BR2 75S mRNA were obtained fromChironomus pallidivittatus. The regular structure characterizing the core of these genes, consisting of tandemly arranged repeat units, changes into a more irregular structure toward the 3′ end. Distal to a standard type of repeat unit with a characteristic excess of positive charges, a new type of repeat with a high, negative charge density is interspersed among parts of the standard unit. The last 111 amino acids before the stop codon represent a unique region distinctly different in amino acid composition from upstream regions, and include two partially homologous hydrophobic regions. Sequence comparison of 3′-end regions from clones representing BR1 and BR2 genes indicates striking sequence conservation in the unique part of the region. Analysis of the level of silent site divergence shows that the homology increases in the 3′ direction up to the polyadenylation site. That the unique region is retained as a part of the secreted protein is shown by Western blotting.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02100037
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  • 2
    Electronic Resource
    Electronic Resource
    Subrepeats within the BR1β repeat unit inChironomus pallidivittatus can be classified into different types depending on codon usage (1988)
    Springer
    Journal of molecular evolution 27 (1988), S. 298-302 
    Details
    ISSN: 1432-1432
    Keywords: Balbiani rings ; cDNA clones ; Nucleotide sequence ; Repeat units ; Subrepeats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A new type of repeat unit was isolated from Balbiani ring 1 ofChironomus pallidivittatus and designated, BR1β repeat. It consists of a constant and a subrepeated part, like previously described units belonging to the core blocks of the BR genes. The subrepeated part contains 10-codon subrepeats with an arrangement similar to the subrepeats of the previously described BR2β gene. The present unit differs from earlier reported core units firstly in a much lower number of copies (about 15) per genome, which are tandemly arranged. Secondly, the number of subrepeats per BR1β repeat unit can show great variations. On the basis of the pattern of codon usage, three types of subrepeats can be distinguished. One type lies 5′-proximal in the subrepeat array and consists of variable numbers of subrepeats almost identical at the nucleotide level. The last complete subrepeat represents another type, with consistent differences in codon usage as compared to subrepeats of the proximal type. Finally, there is an intermediate type represented by the subrepeat preceding the distal one. Here, codon characteristics from proximal and distal subrepeats are mixed in a patchy and irregular way. The evolution of the arrays can be understood either as being the result of subrepeat formation in two steps (occurring before and after amplification of whole repeat units) or as the result of a continuous process in which there is evidence for participation of gene conversion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02101191
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  • 3
    Electronic Resource
    Electronic Resource
    Histochemical localization of reverse transcriptase in polytene chromosomes of chironomids (1999)
    Springer
    Chromosoma 108 (1999), S. 302-307 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The localization of a reverse transcriptase-related protein in salivary gland polytene chromosomes was investigated by immunohistochemistry in two species of Chironomus. The antibodies used were raised against a recombinant protein containing phylogenetically conserved motifs of reverse transcriptases and derived from an abundant non-LTR element previously identified in Chironomus. Immunoreactive protein was found in some telomeres, in a centromeric region, in a few interstitial bands and in Balbiani ring 3. The telomeric signal was probably dependent on transcription and increased dramatically when telomeric heat shock puffs were induced. A correlation with transcription was also seen in Balbiani ring 3, the immunobinding of which disappeared after inhibition of transcription with actinomycin D.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004120050381
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  • 4
    Electronic Resource
    Electronic Resource
    Physico-chemical properties of chromosomal RNA in Chironomus tentans polytene chromosomes (1969)
    Springer
    Chromosoma 28 (1969), S. 379-398 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Labelled chromosomal RNA of the dipteran Chironomus tentans was studied with respect to its migration properties during electrophoresis in agarose. The RNA was isolated from polytene chromosomes which had been microdissected from fixed salivary glands and obtained free from nucleoli and nuclear sap. Labelled material migrates as 4–5 S RNA and as polydisperse material in a range where the lower limit corresponds to 10–15 S, the upper limit to 80–90 S RNA and the maximum in the distribution to 30–40 S RNA. The data indicate that the latter fractions are formed by unbroken, single-stranded RNA molecules, partly of very high molecular weights. It is shown in a number of tests that the distribution is not a consequence of formation of complexes or aggregates between RNA molecules on one hand and DNA, proteins or other RNA molecules on the other.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00284256
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  • 5
    Electronic Resource
    Electronic Resource
    Chromosomal RNA synthesis in polytene chromosomes of Chironomus tentans (1969)
    Springer
    Chromosoma 28 (1969), S. 399-417 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The presence of heterogeneous RNA of high molecular weight has been demonstrated on the giant chromosomes, in the nuclear sap and in the cytoplasm of the salivary glands in Chironomus tentans. The kinetic properties of this heterogeneous RNA have also been outlined in some detail. — Salivary glands were incubated for different time intervals (20, 45 and 180 min) in haemolymph, supplemented with tritiated cytidine and uridine. The different cellular components were isolated by micromanipulation and RNA extracted with an SDS-pronase solution and analysed with electrophoresis in agarose. — Heterogeneous, high molecular weight RNA with a peak around 35 S was saturated with label on chromosome I, II and III in 45 min, although the synthetic capacity was unchanged during at least 180 min incubation. This indicated a complete turnover of heterogeneous RNA on the chromosomes in less than 45 min. The turnover time in the giant puffs (the so called Balbiani rings) on the fourth chromosome, was even shorter and estimated to less than 30 min. No shift in the electrophoretic pattern of this heterogeneous RNA was found to occur on the chromosomes during long incubation times or during actinomycin D experiments. These labelling characteristics of heterogeneous RNA on the chromosomes indicate that all the different molecules in the heterogeneous RNA have a similar and rapid turnover. A conversion to smaller, stable molecules was excluded. — Heterogeneous RNA of a distribution corresponding to that on the chromosomes was found in the nuclear sap and also in the cytoplasm. The activity in both these cellular compartments increased between 45 and 180 min incubation. The distribution pattern for high molecular weight RNA was in all experiments similar on the chromosomes, in the nuclear sap and in the cytoplasm. It appears that at least a considerable part of the high molecular weight RNA leaves the chromosomes to enter the nuclear sap and lateron to some extent the cytoplasm in this high molecular form. Stable molecules of smaller size (6–15 S) did not appear during 180 min incubation. The data indicate, however, also a substantial breakdown of heterogeneous RNA to acid soluble products during this time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00284257
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  • 6
    Electronic Resource
    Electronic Resource
    RNA synthesis in a Balbiani ring in Chironomus tentans salivary gland cells (1969)
    Springer
    Chromosoma 28 (1969), S. 418-429 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Rapidly labelled RNA in Balbiani ring 2 on chromosome IV in the salivary glands of Chironomus tentans was investigated. This RNA is likely to be transcribed from only one chromosomal band, supposed to be a single operational unit in these polytenic cells (Beermann, 1966). Salivary glands were incubated in larval haemolymph, supplemented with tritiated RNA precursors and fixed afterwards. Balbiani rings 2 (in some experiments also Balbiani ring 1 and 3) were isolated with micromanipulation. The labelled RNA was extracted with SDS-pronase and analysed with electrophoresis in agarose. The rapidly labelled RNA in Balbiani ring 2 was as heterogeneous as RNA from the remainder of the chromosome set (10–90 S) but the peak of the distribution of label in BR 2 corresponded to molecules of about 50 S as compared to that of RNA from the rest of the chromosome set which was about 35 S. When the synthetic activity in Balbiani ring 2 was very high, relatively more molecules with very high molecular weights were produced compared with the state when the synthetic activity was moderate or low. The synthetic activity in Balbiani ring 2 compared to that in Balbiani ring 1 was well correlated to the relative sizes of the two Balbiani rings. The results on Balbiani ring 2 are discussed in relation to the size and structure of the chromomere.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00284258
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  • 7
    Electronic Resource
    Electronic Resource
    Large sized nascent protein as dominating component during protein synthesis in Chironomus salivary glands (1980)
    Springer
    Chromosoma 81 (1980), S. 85-99 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The main secretory protein fractions from Chironomus tentans have been investigated with particular emphasis on the dominant fraction, component 1, here designated I (Grossbach, 1969). This polypeptide was suggested to be the translatory product of 75 S RNA from Balbiani ring 2 (BR2) because of its size and quantitative prominence. Its molecular weight was estimated by gel filtration in 8 M urea at 850,000+101,000 D. During short pulses with radioactive amino acids a large fraction of the label was found in a population of polypeptide chains suggestive of molecules continuously growing to the size of component I. Populations of nascent large protein chains of similar size distribution were dominant in the polysomes and constituted the only population present in the largest polysomes, known to contain 75S RNA from BR2 (and BR1) as predominant or only component (Daneholt et al., 1977; Wieslander and Daneholt, 1977). These data indicate strongly that the large size of component I is not a result of posttranslational modifications. No sequence similarities, using limited proteolysis, were found between component I and component II, both of which have been considered to be BR2 products. There was, furthermore, no detectable immunological identity between component I and smaller secretory protein fractions. The data support Grossbach's and Daneholt's suggestion that component I is closely related to the primary translation product of 75S RNA from the large Balbiani rings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00292424
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  • 8
    Electronic Resource
    Electronic Resource
    Sequences translated by Balbiani ring 75S RNA in vitro are present in giant secretory protein from Chironomus tentans (1980)
    Springer
    Chromosoma 81 (1980), S. 101-113 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The 75S RNA originating in the large Balbiani rings 1 and 2 (BR1 and 2) was isolated and used for in vitro translation in the mRNA dependent reticulocyte lysate. Conditions (K+-concentration, temperature, time etc), were optimized for obtaining translation products of maximal size. Polypeptide chains up to about 500,000 D were obtained but no complete translation products. Tryptic fingerprints were performed on the in vitro products as well as on the secretory protein components nos. I and II+III labelled with 35S-methionine. There was a large degree of correspondence between the fingerprint of the in vitro product and that of component I but less to that of component II+III. The results suggest that 75S RNA with an origin in the BR1 and BR2 codes for the giant secretory protein component I.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00292425
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  • 9
    Electronic Resource
    Electronic Resource
    Concomitant induction of a Balbiani ring and a giant secretory protein in Chironomus salivary glands (1980)
    Springer
    Chromosoma 81 (1980), S. 115-124 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract In normal fourth larval instar Chironomus larvae, the secretory protein component I (or 1, according to Grossbach, 1969) consists of two subfractions, Ia and Ib, with an average molecular weight of 850.000 D (Rydlander and Edström, 1980). Data in the preceding paper suggest that component I is coded for by 75S RNA derived from the two large Balbiani rings, BR1 and BR2 (Rydlander et al., 1980). If Chironomus pallidivittatus larvae are exposed to galactose, the size relations between BR1 and BR2, which are usually in favour of BR2, are inverted and upon prolonged exposure a new BR, BR6, appears (Beermann, 1973). Here we describe how one or two new subfractions within component I, Ic1 and Ic2, appear during treatment with galactose, in parallel with the development of BR6. During the treatment there is also a change in the ratio between Ia and Ib proteins so that Ia becomes dominant, whereas in controls Ib is more pronounced. Fractions Ia, Ib and Ic are at least partially immunologically different but Ic1 and Ic2 cannot be distinguished from each other. Since the relative amounts of Ic1 and Ic2 do not vary in extracts from single animals, we have assumed that they represent alle lic products. —Fraction Ic can become the dominating protein within component I during galactose treatment. Since component I accounts for about 50% of the total protein synthesis, the sugar treatment is accompanied by major quantitative changes in genetic expression. —The correlation between the occurrence of particular Balbiani rings and protein fractions, evident from measurements of either protein mass or amino acid incorporation remains in agreement with the general relation earlier shown to exist between the large Balbiani rings and the total component I. Our data support the hypothesis that BR1 codes for fraction Ia, BR2 for Ib and BR6 for Ic. Conclusive evidence will, however, have to be provided by molecular techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00292426
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  • 10
    Electronic Resource
    Electronic Resource
    A Combined Microphoresis-Autoradiography Technique (1963)
    [s.l.] : Nature Publishing Group
    Nature 197 (1963), S. 89-90 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Tests were performed with graded applications of tracer on microphoresis fibres and with separations of yeast RNA hydrolysate mixed, with tracer. These indicated that autoradiograms of individual bands could be resolved and that the fibre did not interfere with the performance of the emulsion. A ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/197089a0
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