Nuclear Segmentation, Condensation and Bilateral Symmetry in Polymorphonuclear Leukocytes Reflect Genomic Order and Favor Immunologic Function

Segmentation, condensation and bilateral symmetry of the nuclei ofpolymorphonuclear leukocytes seem related to their function.Segmentation of the nuclei into two or more lobes and their condensationfacilitate their passage (diapedesis) through the endothelial layer ofblood vessels to the extravasal space and subsequent locomotion throughthe interstitial compartment of different tissues. Bilateral symmetry ofthese nuclei along with their association to the cytoskeletal fiberscontribute to their efficiency in locomotion by alignment of the axis ofnuclear symmetry to the axis of cellular polarity, which orients towardsthe direction of locomotion in response to cytokines and other stimuli.Observations of the cytogenetic facets of intranuclear order supportthese assumptions

Nuclear Segmentation, Condensation and Bilateral Symmetry in Polymorphonuclear Leukocytes Reflect Genomic Order and Favor Immunologic Function

Segmentation, condensation and bilateral symmetry of the nuclei ofpolymorphonuclear leukocytes seem related to their function.Segmentation of the nuclei into two or more lobes and their condensationfacilitate their passage (diapedesis) through the endothelial layer ofblood vessels to the extravasal space and subsequent locomotion throughthe interstitial compartment of different tissues. Bilateral symmetry ofthese nuclei along with their association to the cytoskeletal fiberscontribute to their efficiency in locomotion by alignment of the axis ofnuclear symmetry to the axis of cellular polarity, which orients towardsthe direction of locomotion in response to cytokines and other stimuli.Observations of the cytogenetic facets of intranuclear order supportthese assumptions

Biphasic Chromatin Structure and FISH Signals Reflect Intranuclear Order

Background and Aim: One of the two parental allelic genes may selectively be expressed, regulated by imprinting, X-inactivation or by other less known mechanisms. This study aims to reflect on such genetic mechanisms. Materials and Methods: Slides from short term cultures or direct smears of blood, bone marrow and amniotic fluids were hybridized with FISH probes singly, combined or sequentially. Two to three hundred cells were examined from each preparation. Results and Aignificance: A small number of cells (up to about 5%), more frequent in leukemia cases, showed the twin features: (1) nuclei with biphasic chromatin, one part decondensed and the other condensed; and (2) homologous FISH signals distributed equitably in those two regions. The biphasic chromatin structure with equitable distribution of the homologous FISH signals may correspond to the two sets of chromosomes, supporting observations on ploidywise intranuclear order. The decondensed chromatin may relate to enhanced transcriptions or advanced replications. Conclusions: Transcriptions of only one of the two parental genomes cause allelic exclusion. Genomes may switch with alternating monoallelic expression of biallelic genes as an efficient genetic mechanism. If genomes fail to switch, allelic exclusion may lead to malignancy. Similarly, a genome-wide monoallelic replication may tilt the balance of heterozygosity resulting in aneusomy, initiating early events in malignant transformation and in predicting cancer mortality

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

Background: One 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. Results: We 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. Conclusions: From 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