Chromosome architecture in the decondensing human sperm nucleus

Abstract

Whereas recent studies demonstrated a well-defined nuclear architecture in human sperm nuclei, little is known about the mode of DNA compaction above the elementary structural unit of nucleoprotamine toroids. Here, using fluorescence in-situ hybridization (FISH) with arm-specific DNA probes of chromosomes 1, 2 and 5, we visualized arm domains and established hierarchical levels of sperm chromatin structures. The compact chromosome territories, which in sperm have a preferred intranuclear localization, have an extended conformation represented by a 2000 nm chromatin fiber. This fiber is composed of a 1000 nm chromatin thread bent at 180° near centromere. Two threads of 1000 nm, representing p-arm and q-arm chromatin, run in antiparallel fashion and join at the telomeres. Each 1000 nm thread, in turn, resolves into two rows of chromatin globules 500 nm in diameter interconnected with thinner chromatin strands. We propose a unified comprehensive model of chromosomal and nuclear architecture in human sperm that, as we suggest, is important for successful fertilization and early development.

Nuclear organization during in vitro differentiation of porcine mesenchymal stem cells (MSCs) into adipocytes

“…Usually, telomeres are evenly distributed in mammalian cell nuclei; however, in some cell types (e.g., sperm), they are preferentially located in the nuclear periphery (Mudrak et al 2005). In our study, we observed no changes in the number or distribution of telomeres when MSCs and mature adipocytes were compared.…”

Erasure of the paternal transcription program during spermiogenesis: The first step in the reprogramming of sperm chromatin for zygotic development

“…Protocol B: The cell suspension was fixed with 0.05% paraformaldehyde in PBS, decondensed with 10 mM DTT and 0.5 mg/ml heparin for 30 min (Mudrak et al, 2005), smeared onto slides, and air-dried. The cells were washed 3 times in PBS and incubated with primary and secondary antibodies, as done in Protocol A.…”

“…Before immunochemistry, testis cells or mature sperm were prefixed with 0.05% paraformaldehyde in PBS and decondensed with 10 mM DTT and 0.5 mg/ml heparin for 30 min (Mudrak et al, 2005). Alternatively, the cells were decondensed with 10 mmol/L DTT and 4 mmol/L lithium diiodosalicylate (LIS) in 100 mmol/L Tris-HCl (pH 8.0) for 45 min (Wyrobek et al, 1990), airdried, and fixed with 100% cold methanol.…”

Kinetics of human male pronuclear development in a heterologous ICSI model

“…Indeed, in human sperm, chromosomes occupy defined preferred intranuclear positions [7,10,38]. Paternal genome is activated early after fertilization, during S/G2 phase of the first cell cycle i.e.…”

“…Nonetheless, chromosome topology in gametes and zygotes is poorly studied. Recent studies clearly demonstrated that chromosomes in mature human spermatozoa have nonrandom, well-defined, and unique spatial organization [5][6][7]. In addition, sperm chromosomes have a preferred intracellular positioning [8][9][10].…”