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1.
G. Badaracco L. Baratelli E. Ginelli R. Meneveri P. Plevani P. Valsasnini C. Barigozzi 《Chromosoma》1987,95(1):71-75
The genus Artemia (Crustacea, Phyllopoda) is widely distributed all over the world as a result partly of natural colonization and partly of spread by birds and man. Artemia offers a very interesting model for speciation studies, since the genus comprises both bisexual sibling species and parthenogenetic populations, exhibiting different chromosome numbers (diploidy, heteroploidy and polyploidy). The finding of the clustered repetitive AluI DNA family in the heterochromatin of A. franciscana can provide a useful tool for investigating the relationship between the members of the genus Artemia at the molecular level. Sixteen strains of Artemia, comprising sibling species and parthenogenetic populations, were analysed for the presence of AluI repetitive DNA by dot-blot hybridization. The observed variation in the content of repetitive DNA together with genetical, biological and geological data, support the hypothesis that Artemia living in the New World are derived from ancestral species that evolved in the Mediterranean area. 相似文献
2.
DNA bending has been suggested to play a role in the regulation of gene expression, initiation of DNA replication, site specific recombination and DNA packaging. In Artemia franciscana (Phillopoda anostraca) cells we have revealed that an AluI DNA family of repeats, 113-bp in length, is the major component of the constitutive heterochromatin found in the species. By analysis of cloned oligomeric (monomer to hexamer) heterochromatic fragments and electrophoretic experiments we verified that the repetitive DNA shows a stable curvature that confers a solenoidal geometry to the double helix. Using the cloned monomeric fragment, as molecular probe, we describe the detection in an A. franciscana cell extract of a protein of 82 kDa (p82) that preferentially binds to heterochromatic DNA. This protein, purified of the other DNA binding proteins present in the crude cell extract, shows a greater affinity with the tandem copies of the AluI DNA fragment than with the monomer sequence. The binding of p82 protein to heterochromatic DNA is also drastically reduced in the presence of the antibiotic distamycin A, suggesting a role of the DNA curvature in the formation of the nucleoproteic complex. 相似文献
3.
C. Barigozzi G. Badaracco P. Plevani L. Baratelli S. Profeta E. Ginelli R. Meneveri 《Chromosoma》1984,90(5):332-337
A bisexual species of the genus Artemia (Crustacea, Phyllopoda), Artemia franciscana Barigozzi of San Francisco Bay and a parthenogenetic population of Artemia sp. of Tsing-Tao (China), both with 42 chromosomes, were compared with respect to the microscopic structure of the interphase larval nucleus, the microscopical structure of the prophase chromosomes and the DNA structure. — Artemia franciscana exhibits several chromocenters in the resting nucleus, heterochromatic blocks located at the end of the prophase chromosomes, and a large amount of repetitive DNA (Alu I 110-bp fragments). The other Artemia sp. lacks chromocenters, heterochromatic blocks in the chromosomes, and the Alu I DNA. The two populations thus differ by a remarkable amount of repetitive DNA.The authors dedicate this paper to Professor Hans Bauer, on the occasion of his 80th birthday 相似文献
4.
Diogo Cavalcanti Cabral-de-Mello Rita de Cássia de Moura Maria José de Souza 《Genetica》2010,138(2):191-195
5.
《Gene》1997,189(1):13-18
We have previously revealed that in the brine shrimp Artemia franciscana an AluI DNA family of repeats, 113 bp in length, is the major component of the constitutive heterochromatin and that this repetitive DNA shows a stable curvature that confers a solenoidal geometry on the double helix in vitro. It was suggested that this particular structure may play a relevant role in determining the condensation of the heterochromatin. In this report we have cloned hexamers of highly-repetitive sequence (AluI-satellite DNA) in proximity to a yeast lacZ reporter gene on a plasmid. We find that the expression of the reporter gene is affected by the presence of this DNA in a dose- and orientation-dependent manner in the yeast, S. cerevisiae. We show that this effect is not dependent on under-replication or re-arrangements of the repetitive DNA in the cell but is due to decreased expression of the reporter gene. Our results indicate that the AluI-satellite DNA of Artemia per se is able to influence gene expression. © 1997 Elsevier Science B.V. All rights reserved. 相似文献
6.
In situ digestion of metaphase and polytene chromosomes and of interphase nuclei in different cell types ofDrosophila nasuta with restriction enzymes revealed that enzymes like AluI, EcoRI, HaeIII, Sau3a and SinI did not affect Giemsa-stainability
of heterochromatin while that of euchromatin was significantly reduced; TaqI and SalI digested both heterochromatin and euchromatin
in mitotic chromosomes. Digestion of genomic DNA with AluI, EcoRI, HaeIII, Sau3a and KpnI left a 23 kb DNA band undigested
in agarose gels while withTaqI, no such undigested band was seen. TheAluI resistant 23 kb DNA hybridized insitu specifically with the heterochromatic chromocentre. It appears that the digestibility of heterochromatin region in genome
ofDrosophila nasuta with the tested restriction enzymes is dependent on the availability of their recognition sites. 相似文献
7.
8.
We molecularly cloned new families of site-specific repetitive DNA sequences from BglII- and EcoRI-digested genomic DNA of the Syrian hamster (Mesocricetus auratus, Cricetrinae, Rodentia) and characterized them by chromosome in situ hybridization and filter hybridization. They were classified
into six different types of repetitive DNA sequence families according to chromosomal distribution and genome organization.
The hybridization patterns of the sequences were consistent with the distribution of C-positive bands and/or Hoechst-stained
heterochromatin. The centromeric major satellite DNA and sex chromosome-specific and telomeric region-specific repetitive
sequences were conserved in the same genus (Mesocricetus) but divergent in different genera. The chromosome-2-specific sequence was conserved in two genera, Mesocricetus and Cricetulus, and a low copy number of repetitive sequences on the heterochromatic chromosome arms were conserved in the subfamily Cricetinae
but not in the subfamily Calomyscinae. By contrast, the other type of repetitive sequences on the heterochromatic chromosome
arms, which had sequence similarities to a LINE sequence of rodents, was conserved through the three subfamilies, Cricetinae,
Calomyscinae and Murinae. The nucleotide divergence of the repetitive sequences of heterochromatin was well correlated with
the phylogenetic relationships of the Cricetinae species, and each sequence has been independently amplified and diverged
in the same genome. 相似文献
9.
Some groups of fish, such as those belonging to the Order Tetraodontiformes, may differ significantly in the amount and location of heterochromatin in the chromosomes. There is a marked variation in DNA content of more than seven-fold among the families of this Order. However, the karyoevolutionary mechanisms responsible for this variation are essentially unknown. The largest genomic contents are present in species of the family Ostraciidae (2.20–2.60 pg). The present study cytogenetically characterized two species of the family Ostraciidae, Acanthostracion polygonius and A. quadricornis, using conventional staining, C-bandings, Ag-NOR, CMA3/DAPI, AluI, PstI, EcoRI, TaqI and HinfI restriction enzymes (REs) and double FISH with 18S and 5S rDNA probes. The karyotypes of both species showed 2n = 52 acrocentric chromosomes (FN = 52; chromosome arms) and pronounced conserved structural characteristics. A significant heterochromatic content was observed equilocally distributed in pericentromeric position in all the chromosome pairs. This condition is unusual in relation to the karyotypes of other families of Tetraodontiformes and probability is the cause of the higher DNA content in Ostraciidae. Given the role played by repetitive sequences in the genomic reorganization of this Order, it is suggested that the conspicuous heterochromatic blocks, present in the same chromosomal position and with apparently similar composition, may have arisen or undergo evolutionary changes in concert providing clues about the chromosomal mechanisms which led to extensive variation in genomic content of different Tetraodontiformes families. 相似文献
10.
We comparatively analyzed six Dichotomius species (Coleoptera: Scarabainae) through cytogenetic methods and mitochondrial genes sequencing in the aim to identify patterns
of chromosomal evolution and heterochromatin differentiation in the group. The chromosomal data were accessed through the
classical analysis of heterochromatin and mapping of high and moderately repeated DNAs (C
0
t-1 DNA fraction). Mitochondrial data were obtained from nucleotide sequences of the cytochrome oxidase I (COI) and 16S rRNA
genes. The heterochromatin distribution was conserved but revealed variability in the base pair richness and repetitive DNA
content, and an intense turnover of heterochromatic associated sequences seems to have occurred during Dichotomius speciation. Specifically for D. bos, an interesting pattern was observed, indicating apparently the presence of heterochromatic sequences composed of low copy-number
sequences. Moreover, highly conserved terminal/sub-terminal sequences that could act as a telomeric or telomere-associated
DNA were observed. The heterochromatin diversification patterns observed in Dichotomius were not accomplished by the diversification of the species studied, which may be a consequence of the intense dynamics that
drive the evolution of repeated DNA clusters in the genome. Finally our findings also suggest that the use of C
0
t-1 DNA fraction represents a powerful, inexpensive and not time consuming tool to be applied in understanding heterochromatin
and repetitive DNA organization. 相似文献
11.
Heterochromatin is a significant component of the human genome and the genomes of most model organisms. Although heterochromatin is thought to be largely non-coding, it is clear that it plays an important role in chromosome structure and gene regulation. Despite a growing awareness of its functional significance, the repetitive sequences underlying some heterochromatin remain relatively uncharacterized. We have developed a real-time quantitative PCR-based method for quantifying simple repetitive satellite sequences and have used this technique to characterize the heterochromatic Y chromosome of Drosophila melanogaster. In this report, we validate the approach, identify previously unknown satellite sequence copy number polymorphisms in Y chromosomes from different geographic sources, and show that a defect in heterochromatin formation can induce similar copy number polymorphisms in a laboratory strain. These findings provide a simple method to investigate the dynamic nature of repetitive sequences and characterize conditions which might give rise to long-lasting alterations in DNA sequence. 相似文献
12.
Restriction endonucleases have been used to digest DNA in fixed metaphase chromosomes of animal species. However, constitutive C-heterochromatin of plant species is resistant to these enzymes suggesting that the special structural organization of plant C-bands is an impediment to the activity of restriction endonucleases. In order to test this hypothesis, we have chosen the species Scilla siberica, whose purified satellite DNA, localised at the heterochromatic regions, is extensively digested by HaeIII. In situ treatment with HaeIII alone does not produce significant digestion of heterochromatin, but subsequent treatment with proteinase K results in extensive digestion of heterochromatic regions producing unstained gaps. These results indicate that HaeIII is able to access and cut chromosomal DNA from C-bands, but the DNA fragments remain attached to chromosomal proteins that characterize the complex structure of heterochromatin in this species. Although there are no reasons to suppose that accessibility of chromosomal DNA of S. siberica to restriction enzymes can be impeded, it would be reasonable to think from our results that some special features of heterochromatin organization in plants contribute to the formation of a complex structure that makes chromosomal DNA extraction impossible.by D. Schweizer 相似文献
13.
Evolutionary forces acting on the repetitive DNA of heterochromatin are not constrained by the same considerations that apply to protein-coding genes. Consequently, such sequences are subject to rapid evolutionary change. By examining the Troponin C gene family of Drosophila melanogaster, which has euchromatic and heterochromatic members, we find that protein-coding genes also evolve in response to their chromosomal location. The heterochromatic members of the family show a reduced CG content and increased variation in DNA sequence. We show that the CG reduction applies broadly to the protein-coding sequences of genes located at the heterochromatin:euchromatin interface, with a very strong correlation between CG content and the distance from centric heterochromatin. We also observe a similar trend in the transition from telomeric heterochromatin to euchromatin. We propose that the methylation of DNA is one of the forces driving this sequence evolution. 相似文献
14.
The extent of conservation of constitutive heterochromatin in three species of Mus viz. M. musculus, M. booduga and M. dunni, with shared cytological properties and homologous DNA sequences has been studied. The cytological properties were investigated by doing fluorescence staining and condensation inhibition of their chromosomes with Hoechst 33258. Both the parameters indicate the occurrence of a reduced quantum of M. musculus like heterochromatin at specific sites in the other two genomes. In situ hybridization of the nick translated 3H-labelled M. musculus satellite DNA with M. booduga and M. dunni chromosomes, also corroborates our Hoechst 33258 findings and comparable variation in the amount and site of occurrence of sequences homologous to M. musculus satellite DNA in these species are noticed. The study thus provides a good example of a gradual quantitative variation of a particular type of heterochromatin and in turn of the repetitive DNA constituting it in different related species. Further since the heterochromatin in M. booduga and M. dunni is expected to contain different repetitive DNA sequences in addition to those homologous to M. musculus satellite DNA, it is proposed that a change in the balance between two or more repetitive sequences in heterochromatin may be more crucial in its evolutionary consequences rather than a mere increase or decrease of a homogeneous repetitive sequence. 相似文献
15.
In Drosophilatwo non-LTR retrotransposons, HeT-Aand TART, offer a novel experimental system for the study of heterochromatin. These elements, found only in heterochromatin, form
Drosophilatelomeres by repeated transposition onto chromosome ends. Their transposition yields arrays of repeats larger and more irregular
than the repeats produced by telomeras; nevertheless, the transpositions are, in principle, equivalent to the telomere-building
action of telomerase. The identification of the HeT-Apromoter has given the first view of the molecular structure of a promoter active in heterochromatin. These telomere-specific
elements are unusual in having a large amount of non-coding sequence. Like many other heterochromatic sequences, the HeT-Anon-coding sequence has a repetitive organization strongly conserved within the species, although the sequence itself can
undergo significant change between species (atypical example of concerted evolution). Such heterochromatic sequences could
be important for the cell, perhaps as docking stations for essential proteins.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
16.
A relationship between the sequence of centromere separation and quantity of pericentromeric constitutive heterochromatin
was studied using bone marrow cells ofMus musculus molossinus and three cell lines, viz., SEWA-Rec 4, brain tumor and L-cells, ofM. m. domesticus origin. The timing of separation of a centromere into two daughter centromeres is related to the quantity of pericentromeric
heterochromatin. In these genomes, having qualitatively uniform DNA in their heterochromatin fraction, the chromosomes with
none or small quantities of heterochromatin separate first. These are followed by those chromosomes which have increasingly
larger quantities of heterochromatin. It appears that one function of repetitive DNA (pericentromeric heterochromatin) is
to regulate the timing of separation of centromeres. 相似文献
17.
A diploid cell line from a male embryo of Microtus agrestis has been established. The culture techniques and pertinent morphological and molecular characteristics of the cell line are described. The cells have been in culture for 130 passages and maintain a normal diploid karyotype as judged by the standard and G banding chromosome techniques. The two giant sex chromosomes are visualized in interphase as two long heterochromatic fibers and the study of the repetitive DNA content of total chromatin, constitutive heterochromatin and euchromatin yielded similar results to those previously found in this laboratory for liver and brain of the same species. The use of this cell line as a model for the understanding of mammalian heterochromatin and for the localization of the site of integration of oncogenic viruses in a specific chromatin fraction is discussed. 相似文献
18.
We report here the molecular and cytological characterization of two proteins, ScoHET1 and ScoHET2 (for Sciara coprophila heterochromatin), which associate to constitutive heterochromatin in the dipteran S. coprophila. Both proteins, ScoHET1 of 37 kDa and ScoHET2 of 44 kDa, display two chromodomain motifs that contain the conserved residues
essential for the recognition of methylated histone H3 at lysine 9. We raised antibodies to analyze the chromosomal location
of ScoHET1 and ScoHET2 in somatic and germline cells. In S. coprophila polytene chromosomes, both proteins associate to the pericentromeric regions and to the heterochromatic subterminal bands
of the chromosomes. In germinal nuclei, ScoHET1 and ScoHET2 proteins distribute to the heterochromatic regions of the regular
chromosome complement and are abundantly present along the heterochromatic germline-limited “L” chromosomes. We investigated
histone methylation modifications and found that all heterochromatic regions enriched in ScoHET1/ScoHET2 proteins exhibit
high levels of di- and tri-methylated histone H3 at lysine 9. Taken together, our results support that the association of
ScoHET1/ScoHET2 to heterochromatin is mediated by histone H3K9 methylation. Using 5-methylcytosine antibodies, we proved the
cytological detection of DNA methylation in S. coprophila. From our observations in L germline chromosomes, heterochromatin in S. coprophila is highly enriched in DNA 5-methylcytosine residues.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
19.
A chromosome 1 (Cr1) pericentric inversion is described in six of seven species in the genus Ctenomys (tuco-tucos) from Uruguay. The inversion was inferred from G-band analyses of subtelocentric Cr1 hypothesised to be derived
from the ancestral metacentric condition. Cr1 varies across species in heterochromatin amount and localisation including a
metacentric chromosome without positive C-bands in C. torquatus, a subtelocentric chromosome with heterochromatic short arms in C. rionegrensis, and a subtelocentric chromosome negative after C-banding in five of the species analysed here. Pachytene chromosomes from
C. rionegrensis, a species with the highest heterochromatin content, and C. torquatus, one of the species with the lowest heterochromatin content, were analysed in order to assess possible mechanisms of heterochromatin
evolution. This analysis revealed the presence of three heterochromatic chromocenters in C. rionegrensis where bivalents converge, while in C. torquatus only one chromocenter was observed. In both species, highly repetitive DNA was observed, localised in chromocenters after
“in situ” hybridisation. Heterochromatin associated protein M31 was localised in chromocenters of both species after immuno-detection.
The spread of heterochromatin in Ctenomys chromosomes could be produced by chromatin exchanges at the chromocenter level. We propose the exchange of this DNA associated
proteins between non-homologous chromosomes in pachytene to be the responsible for the spread of heterochromatin through the
karyotypes of species like C. rionegrensis 相似文献
20.
cis-Acting determinants of heterochromatin formation on Drosophila melanogaster chromosome four
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Sun FL Haynes K Simpson CL Lee SD Collins L Wuller J Eissenberg JC Elgin SC 《Molecular and cellular biology》2004,24(18):8210-8220
The heterochromatic domains of Drosophila melanogaster (pericentric heterochromatin, telomeres, and the fourth chromosome) are characterized by histone hypoacetylation, high levels of histone H3 methylated on lysine 9 (H3-mK9), and association with heterochromatin protein 1 (HP1). While the specific interaction of HP1 with both H3-mK9 and histone methyltransferases suggests a mechanism for the maintenance of heterochromatin, it leaves open the question of how heterochromatin formation is targeted to specific domains. Expression characteristics of reporter transgenes inserted at different sites in the fourth chromosome define a minimum of three euchromatic and three heterochromatic domains, interspersed. Here we searched for cis-acting DNA sequence determinants that specify heterochromatic domains. Genetic screens for a switch in phenotype demonstrate that local deletions or duplications of 5 to 80 kb of DNA flanking a transposon reporter can lead to the loss or acquisition of variegation, pointing to short-range cis-acting determinants for silencing. This silencing is dependent on HP1. A switch in transgene expression correlates with a switch in chromatin structure, judged by nuclease accessibility. Mapping data implicate the 1360 transposon as a target for heterochromatin formation. We propose that heterochromatin formation is initiated at dispersed repetitive elements along the fourth chromosome and spreads for approximately 10 kb or until encountering competition from a euchromatic determinant. 相似文献