Differentielle DNS-Replikation in den Speicheldr�sen-Chromosomen von Chironomus thummi

Keyl, H. G.; Pelling, Claus

doi:10.1007/bf00326784

Cited by 110 publications

(22 citation statements)

References 8 publications

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“…Morphological and biochemical differences between specific homologous bands or segments in the chromosomes of the two subspecies have been described earlier (15)(16)(17)(18)33). It is interesting to note that all bands that have been found to contain strikingly different amounts of H1 variant I-1 in the two subspecies also show morphological differences (15,33).…”

Section: Resultsmentioning

confidence: 65%

“…thummi chromosome regions with a high content of H1 I-1 differ from their homologous C. th. piger counterparts also in that they contain more and repetitive DNA (15,16), replicate late in S phase (17), and/or react positively in a C-banding staining procedure (18). It appears that a high percentage of H1 variant I-1 is characteristic of a specific type of chromatin.…”

mentioning

confidence: 99%

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Histone H1 in two subspecies of Chironomus thummi with different genome sizes: homologous chromosome sites differ largely in their content of a specific H1 variant.

Mohr

Trieschmann²,

Grossbach³

1989

Proc. Natl. Acad. Sci. U.S.A.

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Chromatin of Chironomus thummi (Diptera) contains seven sequence variants of histone Hi. A structurally divergent Hi, variant I-1, accounts for about 20% of the total Hi in C. th. piger and for about 30% in C. th. thummi.Monoclonal antibodies against this protein have been induced and have revealed its restriction to the centromeres and to a limited number of other bands in the salivary gland chromosomes. Indirect inmunofluorescence of the somatically paired homologous chromosomes of F1 hybrids indicates that the difference between the two subspecies in Hi I-1 content largely depends on differences situated at a number of distinct homologous chromosome bands. These bands were intensely decorated by antibodies against Hi I-1 in C. th. thummi but appeared virtually black in C. th. piger. The same bands, however, were decorated equally in both subspecies by an antibody that reacts with other Hi variants but does not recognize Hi I-1 and by a polyclonal anti-Hi antibody. The results suggest that Hi variant I-1 is characteristic of a specific type of chromatin that is confined to distinct chromosome segments and that is more frequent in the subspecies C. th. thummi, which has a 27% larger genome.reported earlier, larvae of C. thummi contain seven different sequence variants of histone H1 (12-14). Salivary gland nuclei contain several different and possibly all seven H1 variants. Antibodies that recognize either a subset of the H1 complement or one single H1 variant have been induced and have been used in the present study to decorate larval salivary gland chromosomes. We find that a specific H1 variant, I-1, is abundant in a limited number of chromosome bands, while it is rare or virtually absent in the chromatin of other chromosome regions. A comparison of two subspecies, C. th. thummi and C. th. piger, which differ remarkably in their total content of H1 variant I-1, revealed that this difference is largely confined to differences between specific homologous chromosome bands. Many of the C. th. thummi chromosome regions with a high content of H1 I-1 differ from their homologous C. th. piger counterparts also in that they contain more and repetitive DNA (15,16), replicate late in S phase (17), and/or react positively in a C-banding staining procedure (18). It appears that a high percentage of H1 variant I-1 is characteristic of a specific type of chromatin.In the periodic structural element of chromatin, the nucleosome, DNA is associated with octameric protein complexes containing pairs of molecules of each of four types of histones. The folding ofthis chain of nucleosomes into the 30-nm fiber of eukaryote chromatin is mediated by the binding of another type ofhistone, H1 (1). Numerous organisms and cell types have been found to contain several different subtypes of H1 (for reviews, see refs. 2, 3), but the functional role of this heterogeneity is not known.In the course of spermiohistogenesis in mammals (4-6) and erythrocyte maturation (7-9), most of the nuclear H1 molecules are replaced by other members of...

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Section: Resultsmentioning

confidence: 65%

mentioning

confidence: 99%

Histone H1 in two subspecies of Chironomus thummi with different genome sizes: homologous chromosome sites differ largely in their content of a specific H1 variant.

Mohr

Trieschmann²,

Grossbach³

1989

Proc. Natl. Acad. Sci. U.S.A.

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“…(1968) lent their support for the conclusions drawn by Keyl and Felling (1963). Most noteworthy, they observed definite labelling tracks in the interchromomeric regions; but, due to inherent limitations of the auto radiographic techniques employed, they were unable to conclusively determine whether the replication of these connecting fibers were under the coordinate control of the adjacent band(s).…”

Section: Significance and Properties Of Polytene Chromosomesmentioning

confidence: 92%

“…However, the conclusions drawn by both Keyl and Felling (1963) as an independent replicon, the determination of the initiation site, when accomplished, will draw attention to the unit char acter of the chromomere and the regulatory controls it may exert on one or both adjacent interbands. Assuming for the moment that each chromomere represents an independent replicon, it is tempting to suppose that initiation begins at a point within the band itself (sequence specific for the required polymerase), proceeds bidirectionally, and includes equal or unequal lengths of DNA in both adjacent interbands.…”

Section: Significance and Properties Of Polytene Chromosomesmentioning

confidence: 99%

An analysis of the Notch locus in Drosophila melanogaster

Welter

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“…Durante anos, o interesse por estes cromossomos concentrou-se no cromômero, considerado a unidade de replicação cromossômica (Keyl & Pelling, 1963;Plaut, 1963) e também a unidade genética funcional (Beermann, 1972).…”

Section: Cromossomos Politênicosunclassified

Aspectos da estrutura da cromatina e da atividade de transcrição induzida na glândula salivar de Rhynchosciara americana (Diptera: Sciaridae)

Badaracco¹

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Differentielle DNS-Replikation in den Speicheldr�sen-Chromosomen von Chironomus thummi

Cited by 110 publications

References 8 publications

Histone H1 in two subspecies of Chironomus thummi with different genome sizes: homologous chromosome sites differ largely in their content of a specific H1 variant.

Histone H1 in two subspecies of Chironomus thummi with different genome sizes: homologous chromosome sites differ largely in their content of a specific H1 variant.

An analysis of the Notch locus in Drosophila melanogaster

Aspectos da estrutura da cromatina e da atividade de transcrição induzida na glândula salivar de Rhynchosciara americana (Diptera: Sciaridae)

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