Chromosomes in a genome-wise order: evidence for metaphase architecture

Abstract

BackgroundOne fundamental finding of the last decade is that, besides the primary DNA sequence information there are several epigenetic “information-layers” like DNA-and histone modifications, chromatin packaging and, last but not least, the position of genes in the nucleus.ResultsWe postulate that the functional genomic architecture is not restricted to the interphase of the cell cycle but can also be observed in the metaphase stage, when chromosomes are most condensed and microscopically visible. If so, it offers the unique opportunity to directly analyze the functional aspects of genomic architecture in different cells, species and diseases. Another aspect not directly accessible by molecular techniques is the genome merged from two different haploid parental genomes represented by the homologous chromosome sets. Our results show that there is not only a well-known and defined nuclear architecture in interphase but also in metaphase leading to a bilateral organization of the two haploid sets of chromosomes. Moreover, evidence is provided for the parental origin of the haploid grouping.ConclusionsFrom our findings we postulate an additional epigenetic information layer within the genome including the organization of homologous chromosomes and their parental origin which may now substantially change the landscape of genetics.Electronic supplementary materialThe online version of this article (doi:10.1186/s13039-016-0243-y) contains supplementary material, which is available to authorized users.

Mitotic antipairing of homologous and sex chromosomes via spatial restriction of two haploid sets

“…3 G ). The data are not only consistent with previous findings of haploid set separation in triploid cells (9, 42) but also with the parental origin model, in which each haploid set is spatially discrete and compartmentalized.…”

Interchromosomal interactions: A genomic love story of kissing chromosomes

“…For example, are NHCCs formed between paternal–paternal, maternal–maternal, or paternal–maternal chromosomes? Or do they have a random combination, that is, based on a determined order of the genomic architecture (Nagele et al, 1995; Weise et al, 2016)? Addressing this question would require either a molecular or imaging technique that distinguishes between the contacts of parental alleles in an allele-specific manner.…”

From Human Cytogenetics to Human Chromosomics

“…Several studies were completed between 2002 and 2008, largely using FISH-banding to learn more about interphase and chromosome-structures. Studies based on FISH-banding in interphase confirmed that chromosomes principally keep their size and do not get extended like spaghetti during completion of the cell cycle [ 2 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 ]. This finding remains in contradiction to most textbooks, which continue to incorrectly postulate that interphase chromosomes are completely decondensed.…”