Search results for "heterochromatin"
showing 10 items of 53 documents
Characterization of mitotic and meiotic, chromosomes of the vermetid gastropodDendropoma (Novastoa) Petraeum(Monterosato, 1884) (Mollusca, Caenogastr…
1997
Abstract The vermetid gastropod Dendropoma (Novastoa) petraeum from the Northwestern coast of Sicily was investigated karyologically. The count of spermatocyte bivalents at diakinesis gave the haploid number of this species as n=17. The count of mitotic chromosomes in males, females and early developing embryos gave the diploid number as 2n=34. Irrespective of sex, the karyotype of D. petraeum consists of 17 homomorphic chromosome pairs, of which 8 are metacentric, 4 subtelocentric and 5 acrocentric. This species is characterized by the presence of two chromosomes per cell involved in nucleolus organization (NOR) and by a low amount of constitutive heterochromatin.
The Sea Urchin sns5 Chromatin Insulator Improves the Likelihood of Lentiviral Vectors in Erythroid Milieu By Organizing an Independent Chromatin Doma…
2015
Abstract Retroviral vectors are currently the most suitable vehicles for therapeutic gene transfer in hematopoietic stem cells. However, these vectors are known to integrate rather randomly throughout the genome, suffering the so called chromosomal position effects (PE). Such a critical occurrence most probably depends upon the ability of heterochromatin to spread in the inserted vector sequences. Moreover, the use of transgenes imply genotoxicity effects, since the cis-regulatory sequences harbored by the vector can disturb the proper transcription of the resident genes neighboring the integration site, potentially leading to malignant transformation. Due to their enhancer blocker activity…
Mapping CAP-A satellite DNAs by FISH in Sapajus cay paraguay and S. macrocephalus (Platyrrhini, Primates)
2023
Satellite DNAs such as Cap-A sequences are potentially informative taxonomic and phylogenetic markers useful for characterizing primate genomes. They have also been used as cytogenetic markers facilitating species identification in many taxa. The aim of this work is to map Cap-A sequences by FISH (fluorescent in situ hybridization) on two Platyrrhini (Primates) species genomes, Sapajus cay paraguay and S. macrocephalus, in order to study their distribution pattern on chromosomes. The Cap-A probes showed bright signals with almost the same interstitial pattern of distribution in correspondence with C and CMA3 rich regions on six pairs of chromosomes in both Sapajus species. An additional pai…
Cytogenetics in the sacoglossan Oxynoe olivacea (Mollusca: Opisthobranchia): karyotype, chromosome banding and fluorescent in situ hybridization
2000
Developing embryos and sexually mature follicles of the male portion of ovotestis proved to be a suitable material as a source of cleaving cells for advanced cytological investigations on the sacoglossan species Oxynoe olivacea Rafinesque, 1819 (Mollusca: Opisthobranchia). O. olivacea has a diploid chromosomal number of 30 made up of 15 pairs of which six are metacentric/submetacentric (M/SM), four subtelocentric (ST) and five on the borderline between SM and ST. Correspondingly, 15 bivalents occur in spermatocytes at Metaphase I. Constitutive heterochromatin is scarce and restricted to small C-bands seen in five pachytene bivalents. The use of combined silver staining and fluorescent in si…
Ag-NOR and C-banding analysis of spermatocyte chromosomes ofClavelina lepadiformis(Ascidiacea, Aplousobranchiata)
1991
SUMMARYChromosome number n = 9 and 2n = 18 for Clavelina lepadiformis (Ascidiacea, Aplousobranchiata) from the Gulf of Palermo have been determined. Silver staining analysis of testicular cells reveals that within-individual variability in NOR banding patterns is present. Using the C-banding procedure, a very impressive heterochromatin amount seems to characterize the chromosome set of this species.
Brief communication. Karyotype analysis, banding, and fluorescent in situ hybridization in the scarab beetle Gymnopleurus sturmi McLeay (Coleoptera S…
2000
Conventional staining, differential banding, and in situ hybridization with both ribosomal and telomeric probes to mitotic chromosomes of Gymnopleurus sturmi (Scarabaeoidea : Scarabaeidae) are described. The karyotype is distinguished by a pericentric inversion polymorphism in chromosome 3, which is either acrocentric or subtelocentric. Silver staining (Ag-NOR) and chromomycin A3 (CMA3), failed to study the detection of nucleolar organizer regions (NORs), due to the extensive silver and CMA3 stainability of all GC-rich heterochromatin. Fluorescent in situ hybridization (FISH) using a Paracentrotus lividus (Echinodermata) rDNA probe mapped the ribosomal RNA genes (rDNA). FISH with the all-hu…
Spermatocyte chromosome banding studies inBuccinulum corneum (Prosobranchia: Neogastropoda): Variation in silver-NOR banding pattern
1990
Diploid number (2n=72), and haploid number (n=36) forBuccinulum corneum (L. 1758) collected from the Gulf of Palermo in December 1987 were determined. A simple method to obtain nucleolar organizer regions (NOR), and constitutive heterochromatin regions (C-bands) of chromosomes ofB. corneum is described. Analyses of silver-stained chromosome preparations ofB. corneum suggest that a within-individual variability in NOR-banding pattern is present in each of the five specimens analysed.
Massive LINE-1 retrotransposon enrichment in tamarins of the Cebidae family (Platyrrhini, Primates) and its significance for genome evolution
2021
To study heterochromatin distribution differences among tamarins, we applied LINE-1 probes using fluorescence in situ hybridization onto chromosomes of Saguinus mystax, Leontocebus fuscicollis, and Leontopithecus rosalia with the aim to investigate possible evolutionary implications. LINE-1 repeats were shown to be involved in genome architecture and in the occurrence of chromosomal rearrangements in many vertebrates. We found bright LINE-1 probe signals at centromeric or pericentromeric areas, GC rich, on almost all chromosomes in three tamarin species. We also found non-centromeric signals along chromosome arms. In a phylogenetic perspective, we analyzed the pattern of LINE-1 distribution…
Gypsy homologous sequences in Drosophila subobscura (gypsyDS).
1993
Characterization of sequences homologous to the Drosophila melanogaster gypsy transposable element was carried out in Drosophila subobscura (gypsyDS). They were found to be widely distributed among natural populations of this species. From Southern blot and in situ analyses, these sequences appear to be mobile in this species. GypsyDS sequences are located in both euchromatic and heterochromatic regions. A complete gypsyDS sequence was isolated from a D. subobscura genomic library, and a 1.3-kb fragment which aligns with the ORF2 of the D. melanogaster gypsy element was sequenced. Comparisons of this sequence in three species (D. subobscura, D. melanogaster, and D. virilis) indicate that th…
Drosophila Enhancer of Zeste/ESC Complexes Have a Histone H3 Methyltransferase Activity that Marks Chromosomal Polycomb Sites
2002
AbstractEnhancer of Zeste is a Polycomb Group protein essential for the establishment and maintenance of repression of homeotic and other genes. In the early embryo it is found in a complex that includes ESC and is recruited to Polycomb Response Elements. We show that this complex contains a methyltransferase activity that methylates lysine 9 and lysine 27 of histone H3, but the activity is lost when the E(Z) SET domain is mutated. The lysine 9 position is trimethylated and this mark is closely associated with Polycomb binding sites on polytene chromosomes but is also found in centric heterochromatin, chromosome 4, and telomeric sites. Histone H3 methylated in vitro by the E(Z)/ESC complex …