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  • 1
    Digitale Medien
    Digitale Medien
    Dosage compensation and template organisation in Drosophila: In situ transcriptional analysis of the chromatin template activity of the X and autosomes of D. melanogaster strains trisomic for the left arm of the second and third chromosomes (1986)
    Springer
    Chromosoma 94 (1986), S. 285-292 
    Details
    ISSN: 1432-0886
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The chromatin template activity of the fixed polytene chromosomes of larval salivary glands of Drosophila melanogaster strains trisomic for the entire left arm of chromosome 2 or chromosome 3 was monitored using 3H-UTP and Escherichia coli RNA polymerase holoenzyme. The three doses of active loci in the trisomic strains were found to synthesize 30%–40% more RNA than the normal double dose of the same region in the wild-type male and female. The higher template activity of the genes on 2L or 3L in the trisomic strains, had no marked effect on the chromatin template activity of the X chromosomes of the male or female. These results suggest that (1) the template activity of an autosomal gene must be viewed as a basal level, comparable to the female X-chromosome and (2) hyperploids for any region of chromosome 2L or 3L have very little or no recognisable influence on X chromosomal organisation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00290858
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  • 2
    Digitale Medien
    Digitale Medien
    Application and efficiency of scintillation autoradiography for Drosophila polytene chromosomes (1977)
    Springer
    Histochemistry and cell biology 52 (1977), S. 73-84 
    Details
    ISSN: 1432-119X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary A rapid method of autoradiography using the scintillation cocktail (Toluene and scintillation fluid, Omnifluor) has been described earlier. Its application and efficiency have been tested using both 3H-thymidine and 3H-uridine. The optimum time required for processing the autoradiograms has been found to be 24 h dry exposure followed by 48 h in the scintillation mixture. Detailed analysis of the autoradiograms with 3H-uridine reveals that with the rapid method the 100% level of labelling index is reached by 48 h while with the conventional method the same level is reached by 10 to 12 days of dry exposure. The maximum grain density is reached by 16 to 17 days by the conventional method. While by the rapid method, the maximum grain density is approximately 80% of the control, this grain density is reached by 48 h (plus 24 h of dry exposure) and thereafter forms a plateau. With Toluene alone the grain density never exceeds 20%. The background is also relatively low and less variable in the O-T-processed autoradiograms, as compared to the two controls. These results support that the scintillation fluid plays the key role in augmenting the labelling. Furthermore, although the maximum grain density by the rapid technique is 80% of the control, the grain density obtained by the rapid method gives less coincidence and superimposition of grains. On the other hand, with 3H-thymidine, although all labelling patterns could be resolved, the labelling index (i.e., percent of labelled cells) is about 40% at 48 h (plus 24 h) and about 79.5% at 96 h with the rapid method, as compared to about 30% and 44% with the conventional method at the two time points, respectively. Only with 16–17 days' dry exposure the 3H-thymidine labelling index increases to 67%. The frequency of the initial patterns (DD-2C) which are usually less frequent, has been found to have increased with the rapid method. No difference in grain density of labelling of 3H-thymidine could be detected between the rapid method and the conventional method. The resolution of grains also seems to be better by the rapid method, due probably to smaller size and lack of superimposition of grains. Other applications, advantages and limitations have been discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00495816
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  • 3
    Digitale Medien
    Digitale Medien
    In situ transcription analysis of chromatin template activity of the X-chromosome of Drosophila following high molar NaCl treatment (1981)
    Springer
    Chromosoma 82 (1981), S. 515-523 
    Details
    ISSN: 1432-0886
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The chromatin template activity of the polytene chromsomes in larval salivary glands of Drosophila hydei has been assayed by in situ transcription, on the fixed chromatin using E. coli RNA polymerase holoenzyme and 3H-UTP as the monitoring substrate, both with optimal salt and high salt concentration (1 M NaCl). Results reveal an increase in the net transcription of all chromosomes in the high salt treatment series in comparison with the control. The X-chromosomes of the male larval gland also shows an increase in the labelling following the high salt treatment, but the increase is significantly less than that of the autosomes of the same nucleus. On the basis of these findings it has been suggested that the X-chromosomal hyperactivity of the male, as normally known to exist, might be guided by an inherent modulation of the structure of the X-chromatin.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00295010
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  • 4
    Digitale Medien
    Digitale Medien
    X chromosomal organisation and dosage compensation (1985)
    Springer
    Chromosoma 91 (1985), S. 259-266 
    Details
    ISSN: 1432-0886
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The chromatin template activity of the polytene X chromosomal DNA was assayed by in situ transcription on the fixed polytene chromosomes using E. coli RNA polymerase holoenzyme and 3H-UTP as the monitoring substrate in various 1X2A, 2X2A and 3X2A larvae and 1X2A (+X fragments) segmental aneuploid larvae of Drosophila melanogaster. The segmental aneuploids contained duplications for the segments 15EF-20F, 11A-20F, 8C-20F and 3E-20F of the X chromosome. Results revealed that a double dose of active loci located in the X chromosome regions 15EF-20F, 11A-20F, and 8C-20F in aneuploids synthesized nearly 40%–70% more RNA than the normal single dose of this region in the wild-type males. The activity per gene dose for the two segments in the aneuploids was also significantly higher than in their male counterpart except for the duplication dp (3E-20F), where the duplicated piece extended from the centromeric heterochromatin to include 85% of the euchromatic portion of the X chromosome. In the case of dp (3E-20F), the X chromosome was transcribed at the lower, “female” level. It may also be noted that some regions of the X chromosome when present in extra copy, especially in dp (8C-20F) influenced the template activity of the X-linked genes inside or outside the duplicated segment. Metafemales (3X2A) have 50% higher template activity of the X chromosomes than their diploid sisters. In this study, metafemales behaved as females with duplication. These results suggest that (1) dosage compensation involves changes in the template activity of the X chromosome and (2) the regulatory sequences involved in dosage compensation in Drosophila are located on the X chromosome and are polygenic.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00328221
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  • 5
    Digitale Medien
    Digitale Medien
    Trace elements in the atmospheric aerosols at Delhi, North India (1985)
    Springer
    Journal of atmospheric chemistry 2 (1985), S. 273-285 
    Details
    ISSN: 1573-0662
    Schlagwort(e): Total suspended particulates (TSP) ; enrichment factor ; trace elements ; ionic balance
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Geologie und Paläontologie
    Notizen: Abstract The total suspended particulate (TSP) levels at Delhi (north India) were measured on 116 days between February and October 1980. The observations were stratified according to season and the values of cross-correlation of the TSP and its components were evaluated. High TSP (209 μg m-3) levels were found during the summer period associated with hot and dry weather in the region and low TSP (109 μg m-3) were found during the monsoon period. Most of the TSP mass was associated with natural soil elements, such as Fe, Al, Mn, Ca, and K. Only a fraction of the mass of the TSP was comprised of elements from anthropogenic sources, e.g., Pb, Ni, Cd, Sb, Cu, and Zn. The aerosols at Delhi were potentially basic in nature, unlike those in European countries which are acidic in nature and cause acid rainfall.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00051077
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