Duplikationen von Untereinheiten der chromosomalen DNS w�hrend der Evolution von Chironomus thummi

Keyl, H. G.

doi:10.1007/bf00330079

Cited by 147 publications

(29 citation statements)

References 45 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: 70%

“…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). These are not easily seen after formaldehyde fixation (Fig.…”

Section: Resultsmentioning

confidence: 90%

“…These are not easily seen after formaldehyde fixation (Fig. 4a) but become apparent after ethanol/acetic acid fixation and staining (15,33). Most, but not all, of the bands with a high H1 I-1 content (bars in Figs.…”

Section: Resultsmentioning

confidence: 92%

“…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.…”

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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: 70%

Section: Resultsmentioning

confidence: 90%

Section: Resultsmentioning

confidence: 92%

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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“…The increase of chromomeric DNA by tandem duplications of the chromomere loop. during evolution was suggested by KEYL (1965). The concept implies that large chromomeres should consist of a number of tandem copies of the original chromomeric DNA or at least there should be numerous rather similar sized DNA segments.…”

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confidence: 99%

A cytological view of the functional organization of chromomeres

Sorsa

2009

Hereditas

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The nucleotide sequence of an unusual non-transcribed spacer and its ancestor in the rDNA in Chironomus thummi.

Schmidt¹,

Godwin²

1983

The EMBO Journal

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The nucleotide sequence of the non‐transcribed spacer (NTS) in the ribosomal DNA (rDNA) of Chironomus thummi thummi and Chironomus thummi piger, including major parts of the external transcribed spacer, is described. The NTS of the two subspecies are very different in length, (thummi, 7 kb, piger, 2 kb); this is due to the insertion into the NTS of C.th. thummi of a large cluster of highly repetitive DNA sequences which are not present in the NTS of C. th. piger. The repetitive sequences, called Cla elements, are present in high copy number elsewhere in the genome of C. th. thummi and, in lower copy number, in the genome of C. th. piger in which they are mainly in the centromeric regions. Sequencing of the NTS of thummi and piger yielded information on the junctions between the Cla element cluster and the original NTS sequence, as well as on the sequence of the integration site before the transposition has occurred. The integration site is characterized by a dA cluster at the one end and a dT cluster at the other.

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Duplikationen von Untereinheiten der chromosomalen DNS w�hrend der Evolution von Chironomus thummi

Cited by 147 publications

References 45 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.

A cytological view of the functional organization of chromomeres

The nucleotide sequence of an unusual non-transcribed spacer and its ancestor in the rDNA in Chironomus thummi.

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