Loss of totipotentcy in an early embryo is directed by molecular processes responsible for cell fate decisions. Three dimensional genome organisation is an important factor linking chromatin architecture with stage specific gene expression patterns. Little is known about the role of chromosome organisation in gene expression regulation of lineage specific factors in mammalian embryos. Using bovine embryos as a model we have described these interactions at key developmental stages. Three bovine chromosomes (BTA) that differ in size, number of carried genes, and contain loci for key lineage regulators OCT4, NANOG and CDX2, were investigated. The results suggest that large chromosomes regardless of their gene density (BTA12 gene-poor, BTA5 gene-rich) do not significantly change their radial position within the nucleus. Gene loci however, may change its position within the chromosome territory (CT) and relocate its periphery, when stage specific process of gene activation is required. Trophectoderm specific CDX2 and epiblast precursor NANOG loci tend to locate on the surface or outside of the CTs, at stages related with their high expression. We postulate that the observed changes in CT shape reflect global alternations in gene expression related to differentiation.
- MeSH
- Cell Nucleus genetics MeSH
- Cell Lineage MeSH
- Embryonic Development MeSH
- In Situ Hybridization, Fluorescence MeSH
- Nanog Homeobox Protein genetics metabolism MeSH
- Octamer Transcription Factor-3 genetics metabolism MeSH
- Chromosomes, Mammalian genetics MeSH
- Cattle MeSH
- CDX2 Transcription Factor genetics metabolism MeSH
- Gene Expression Regulation, Developmental MeSH
- Animals MeSH
- Check Tag
- Cattle MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
Recurring chromosomal abnormalities are associated with specific tumour types. The EWSR1 and FLI1 genes are involved in balanced translocation t(11;22)(q24;q12), which is present in more than 85% of Ewing sarcomas. In our previous study, we have found that the fusion genes pertaining to both derivative chromosomes 11 and 22 in Ewing sarcoma cell nuclei are shifted to the midway nuclear position between the native EWSR1 and FLI1 genes. In this contribution we focused our attention at nuclear positioning of other genetic elements of chromosomes 11 and 22 in order to find if the whole derivative chromosomes or only their translocated parts change their nuclear positions in comparison with the native chromosomes. Using repeated fluorescence in situ hybridization and high-resolution cytometry, 2D radial positions of EWSR1, BCR, FLI1, BCL1 genes and fluorescence weight centres of chromosome territories were compared for intact and derivative chromosomes 11 and 22 in nuclei of three Ewing sarcoma samples. Significant radial shift was obtained for the derivative EWSR1, FLI1 and BCL1 genes and for the derivative chromosome 11 compared with the intact ones and not very significant for chromosome 22 and the BCR gene. Our results also suggest that the mean nuclear positions of fusion genes are determined by the final structure of the derivative chromosomes and do not depend on the location of the translocation event.
- MeSH
- Cell Nucleus genetics MeSH
- Chromosome Aberrations MeSH
- Sarcoma, Ewing genetics pathology MeSH
- Financing, Organized MeSH
- Gene Dosage MeSH
- In Situ Hybridization, Fluorescence MeSH
- Humans MeSH
- Chromosomes, Human, Pair 11 MeSH
- Chromosomes, Human, Pair 22 MeSH
- Lymphocytes cytology MeSH
- Neoplasms, Bone Tissue genetics pathology MeSH
- Probability MeSH
- Calmodulin-Binding Proteins physiology genetics MeSH
- RNA-Binding Proteins physiology genetics MeSH
- Proto-Oncogene Protein c-fli-1 physiology genetics MeSH
- Sequence Homology, Nucleic Acid MeSH
- Translocation, Genetic MeSH
- Cell Size MeSH
- Check Tag
- Humans MeSH
- Female MeSH
- Publication type
- Comparative Study MeSH
During interphase, the chromosomes of eukaryotes decondense and they occupy distinct regions of the nucleus, called chromosome domains or chromosome territories (CTs). In plants, the Rabl's configuration, with telomeres at one pole of nucleus and centromeres at the other, appears to be common, at least in plants with large genomes. It is unclear whether individual chromosomes of plants adopt defined, genetically determined addresses within the nucleus, as is the case in mammals. In this study, the nuclear disposition of alien rye and barley chromosomes and chromosome arm introgressions into wheat while using 3D-FISH in various somatic tissues was analyzed. All of the introgressed chromosomes showed Rabl's orientation, but their relative positions in the nuclei were less clear. While in most cases pairs of introgressed chromosomes occupied discrete positions, their association (proximity) along their entire lengths was rare, and partial association only marginally more frequent. This arrangement is relatively stable in various tissues and during various stages of the cell cycle. On the other hand, the length of a chromosome arm appears to play a role in its positioning in a nucleus: shorter chromosomes or chromosome arms tend to be located closer to the centre of the nucleus, while longer arms are more often positioned at the nuclear periphery.
- MeSH
- Cell Nucleus MeSH
- Chromatin genetics MeSH
- Chromosomes, Plant * MeSH
- In Situ Hybridization, Fluorescence * methods MeSH
- Interphase * genetics MeSH
- Hordeum genetics MeSH
- Image Processing, Computer-Assisted MeSH
- Flow Cytometry MeSH
- Triticum genetics MeSH
- Secale genetics MeSH
- Publication type
- Journal Article MeSH
Chromosome painting (CP) refers to visualization of large chromosome regions, entire chromosome arms, or entire chromosomes via fluorescence in situ hybridization (FISH). For CP in plants, contigs of chromosome-specific bacterial artificial chromosomes (BAC) from the target species or from a closely related species (comparative chromosome painting, CCP) are typically applied as painting probes. Extended pachytene chromosomes provide the highest resolution of CP in plants. CP enables identification and tracing of particular chromosome regions and/or entire chromosomes throughout all meiotic stages as well as corresponding chromosome territories in premeiotic interphase nuclei. Meiotic pairing and structural chromosome rearrangements (typically inversions and translocations) can be identified by CP. Here, we describe step-by-step protocols of CP and CCP in plant species including chromosome preparation, BAC DNA labeling, and multicolor FISH.
Human embryonic stem cells (hES) are unique in their pluripotency and capacity for self-renewal. Therefore, we have studied the differences in the level of chromatin condensation in pluripotent and all-trans retinoic acid-differentiated hES cells. Nuclear patterns of the Oct4 (6p21.33) gene, responsible for hES cell pluripotency, the C-myc (8q24.21) gene, which controls cell cycle progression, and HP1 protein (heterochromatin protein 1) were investigated in these cells. Unlike differentiated hES cells, pluripotent hES cell populations were characterized by a high level of decondensation for the territories of both chromosomes 6 (HSA6) and 8 (HSA8). The Oct4 genes were located on greatly extended chromatin loops in pluripotent hES cell nuclei, outside their respective chromosome territories. However, this phenomenon was not observed for the Oct4 gene in differentiated hES cells, for the C-myc gene in the cell types studied. The high level of chromatin decondensation in hES cells also influenced the nuclear distribution of all the variants of HP1 protein, particularly HP1 alpha, which did not form distinct foci, as usually observed in most other cell types. Our experiments showed that unlike C-myc, the Oct4 gene and HP1 proteins undergo a high level of decondensation in hES cells. Therefore, these structures seem to be primarily responsible for hES cell pluripotency due to their accessibility to regulatory molecules. Differentiated hES cells were characterized by a significantly different nuclear arrangement of the structures studied.
- MeSH
- Cell Differentiation genetics drug effects MeSH
- Cell Nucleus genetics ultrastructure MeSH
- Cell Line MeSH
- Chromosomal Proteins, Non-Histone genetics metabolism MeSH
- Embryonic Stem Cells metabolism ultrastructure MeSH
- Financing, Organized MeSH
- Humans MeSH
- Pluripotent Stem Cells metabolism ultrastructure MeSH
- Chromatin Assembly and Disassembly MeSH
- Signal Transduction genetics MeSH
- Trans-Activators metabolism drug effects MeSH
- Tretinoin MeSH
- Binding Sites genetics MeSH
- Check Tag
- Humans MeSH
The Neotropical monophyletic catfish genus Harttia represents an excellent model to study karyotype and sex chromosome evolution in teleosts. Its species split into three phylogenetic clades distributed along the Brazilian territory and they differ widely in karyotype traits, including the presence of standard or multiple sex chromosome systems in some members. Here, we investigate the chromosomal rearrangements and associated synteny blocks involved in the origin of a multiple X1X2Y sex chromosome system present in three out of six sampled Amazonian-clade species. Using 5S and 18S ribosomal DNA fluorescence in situ hybridization and whole chromosome painting with probes corresponding to X1 and X2 chromosomes of X1X2Y system from H. punctata, we confirm previous assumptions that X1X2Y sex chromosome systems of H. punctata, H. duriventris and H. villasboas represent the same linkage groups which also form the putative XY sex chromosomes of H. rondoni. The shared homeology between X1X2Y sex chromosomes suggests they might have originated once in the common ancestor of these closely related species. A joint arrangement of mapped H. punctata X1 and X2 sex chromosomes in early diverging species of different Harttia clades suggests that the X1X2Y sex chromosome system may have formed through an X chromosome fission rather than previously proposed Y-autosome fusion.
- MeSH
- Y Chromosome MeSH
- Phylogeny MeSH
- In Situ Hybridization, Fluorescence MeSH
- Sex Chromosomes genetics MeSH
- Catfishes * genetics MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- MeSH
- Fusion Proteins, bcr-abl genetics MeSH
- Cyclin D1 genetics MeSH
- DNA-Binding Proteins genetics MeSH
- Sarcoma, Ewing genetics MeSH
- Oncogene Proteins, Fusion genetics MeSH
- Humans MeSH
- Chromosomes, Human, Pair 11 genetics MeSH
- Chromosomes, Human, Pair 22 genetics MeSH
- Check Tag
- Humans MeSH
- Publication type
- Comparative Study MeSH
