title: Nonrandom location and orientation of the inactive X chromosome in human neutrophil nuclei.
abstract: The nuclei of human neutrophils typically consist of a linear array of three or four lobes joined by DNA-containing filaments. Terminal lobes are connected to internal lobes via a single filament, while internal lobes have two filaments, each to an adjacent lobe. Some lobes also have appendages of various shapes and sizes. In particular, up to 17% of neutrophil nuclei of healthy women exhibit a drumstick-shaped appendage that contains the inactive X chromosome. This report provides a detailed analysis of the relationship between nuclear morphology and the location of the X and Y chromosomes in human neutrophils. Fluorescent in situ hybridization analysis revealed that the X and the Y chromosomes of male neutrophil nuclei are randomly distributed among nuclear lobes. Similarly, in female neutrophil nuclei with a drumstick appendage, the active X chromosome is also randomly distributed among lobes. In contrast, the inactive X chromosome is preferentially located in a terminal lobe in over 90% nuclei with drumsticks. Within the terminal lobe of nuclei with drumsticks, the inactive X chromosome lies distal to the point of filament attachment in 80% of the nuclei. The inactive X chromosome also exhibits a specific orientation within the drumstick appendage, with over 95% of nuclei having the X centromere located toward the tip of the appendage. Female nuclei without a drumstick appendage also have one of the X chromosomes (presumably the inactive chromosome) preferentially situated in a terminal lobe. Nonrandom distribution of the inactive X chromosome is discussed in the context of a model that considers chromosomes as determinants of neutrophil nuclear morphology.
authors.affiliation: Department of Biology, Brandeis University, Waltham, MA 02454-0911, USA.
authors.forename: R J
authors.initials: RJ
authors.lastname: Karni
authors.forename: L J
authors.initials: LJ
authors.lastname: Wangh
authors.forename: J A
authors.initials: JA
authors.lastname: Sanchez
mesh_terms: D002467:Cell Nucleus / Q000235:genetics* / Q000648:ultrastructure; D004303:Dosage Compensation, Genetic; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D009504:Neutrophils / Q000648:ultrastructure*; D014960:X Chromosome