Search results for " heterochromatin"

Evidence for male XO sex-chromosome system in Pentodon bidens punctatum (Coleoptera Scarabaeoidea: Scarabaeidae) with X-linked 18S-28S rDNA clusters

2004

In scarab beetle species of the genus Pentodon, the lack of analysis of sex chromosomes in females along with the poor characterization of sex chromosomes in the males, prevented all previous investigations from conclusively stating sex determination system. In this study, somatic chromosomes from females and spermatogonial chromosomes from males of Pentodon bidens punctatum (Coleoptera: Scarabaeoidea: Scarabaeidae) from Sicily have been analyzed using non-differential Giemsa staining. Two modal numbers of chromosomes were obtained: 2n = 20 and 19 in females and males, respectively. This finding along with other karyological characteristics such as the occurrence of one unpaired, heterotypi…

The pattern of histone H4 acetylation on the X chromosome during spermatogenesis of the desert locustSchistocerca gregaria

1996

We have used antibodies directed against histone H4 acetylated at lysine residue 5, 8, 12, or 16 and indirect immunofluorescence microscopy to probe chromosomes from spermatogonia and spermatocytes of the desert locust, Schistocerca gregaria. The autosomes showed bright overall fluorescence, indicative of high levels of H4 acetylation. In contrast, the X chromosome, which is facultatively heterochromatic during spermatogenesis of the locust, remained completely unstained in spermatogonia and secondary spermatocytes and showed only a small terminal fluorescent band in primary spermatocytes. This band probably corresponds to centromere-associated constitutive heterochromatin. Thus, underacety…

The histone deacetylase Rpd3 regulates the heterochromatin structure of Drosophila telomeres

2011

Telomeres are specialized structures at the end of eukaryotic chromosomes that are required to preserve genome integrity, chromosome stability and nuclear architecture. Telomere maintenance and function are established epigenetically in several eukaryotes. However, the exact chromatin enzymatic modifications regulating telomere homeostasis are poorly understood. In Drosophila melanogaster, telomere length and stability are maintained through the retrotransposition of specialized telomeric sequences and by the specific loading of protecting capping proteins, respectively. Here, we show that the loss of the essential and evolutionarily conserved histone deacetylase Rpd3, the homolog of mammal…

UbcD1: from telomere capping to global heterochromatin regulation

2012

CYTOGENETICS OF THE AMPHIPOD JASSA MARMORATA (COROPHIOIDEA: ISCHYROCERIDAE): KARYOTYPE MORPHOLOGY, CHROMOSOME BANDING, FLUORESCENTIN SITUHYBRIDIZATIO…

2000

Abstract Developing embryos proved to be a suitable source of cells for advanced cytological investigations on Amphipods. Conventional karyotyping, Ag- and fluorochrome-staining, C-banding, endonuclease digestion, fluorescent in situ hybridization (FISH) and nuclear DNA flow cytometric assay were tested in the Ischyroceridae Jassa marmorata. The karyotype consists of 6 chromosome pairs of which 5 are metacentric and 1 subtelocentric. The rDNA/FISH revealed that major ribosomal cistrons are located on the telomeric regions in the short arm of pair 6. A marked size variation of hybridization signals was observed. Silver and fluorochrome staining enhanced no chromosome regions. Constitutive he…

The prolyl-isomerase PIN1 is essential for nuclear Lamin-B structure and function and protects heterochromatin under mechanical stress.

2021

Summary: Chromatin organization plays a crucial role in tissue homeostasis. Heterochromatin relaxation and consequent unscheduled mobilization of transposable elements (TEs) are emerging as key contributors of aging and aging-related pathologies, including Alzheimer’s disease (AD) and cancer. However, the mechanisms governing heterochromatin maintenance or its relaxation in pathological conditions remain poorly understood. Here we show that PIN1, the only phosphorylation-specific cis/trans prolyl isomerase, whose loss is associated with premature aging and AD, is essential to preserve heterochromatin. We demonstrate that this PIN1 function is conserved from Drosophila to humans and prevents…