Preferable location of chromosomes 1, 29, and X in bovine spermatozoa.

Chromosome positioning in sperm nucleus may have a functional significance by influencing the sequence of post-fertilization events. In this study we present data on preferential locations of chromosomes 1, 29 and X in spermatozoa. Here we demonstrate that the position of X chromosome in the sperm nucleus is more restricted as compared to the position of chromosome 1, which is about of the same size.

Positioning of chromosomes in human spermatozoa is determined by ordered centromere arrangement.

The intranuclear positioning of chromosomes (CHRs) is a well-documented fact; however, mechanisms directing such ordering remain unclear. Unlike somatic cells, human spermatozoa contain distinct spatial markers and have asymmetric nuclei which make them a unique model for localizing CHR territories and matching peri-centromere domains. In this study, we established statistically preferential longitudinal and lateral positioning for eight CHRs.

Kinetics of human male pronuclear development in a heterologous ICSI model.

Purpose: To evaluate human sperm nuclear chromatin decondensation in a heterologous ICSI system using hamster ova injected with human sperm.

Materials And Methods: Frozen hamster oocytes were injected with Triton X-100 treated sperm and fixed at different time points post ICSI. Oocytes injected with non-treated sperm served as controls.

Reorganisation of human sperm nuclear architecture during formation of pronuclei in a model system.

By fertilisation, two terminally differentiated cells, namely the egg and spermatozoon, are combined to create a totipotent zygote. During this process, the inactive sperm nucleus is transformed into a functional male pronucleus. Recent studies demonstrate that human sperm chromatin has an elaborate multilevel organisation, but almost nothing is known about how sperm chromosomes are transformed during fertilisation.

Characterisation of a human sperm cell subpopulation marked by the presence of the TSH2B histone.

During the process of mammalian spermiogenesis, a significant reorganisation of the chromatin structure occurs involving the sequential substitution of somatic histones with protamines. In the human sperm nucleus, approximately 15% of the basic nuclear protein complement is maintained as histones. Human testis/sperm-specific histone H2B (hTSH2B) is a variant of the histone H2B expressed exclusively in spermatogenic germline cells and present in some mature sperm cells.

Chromosome architecture in the decondensing human sperm nucleus.

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.

Protection of internal (TTAGGG)n repeats in Chinese hamster cells by telomeric protein TRF1.

Chinese hamster cells have large interstitial (TTAGGG) bands (ITs) which are unstable and should be protected by an unknown mechanism. Here, we expressed in Chinese hamster V79 cells green fluorescent protein (GFP)-tagged human TRF1, and found that a major fraction of GFP-TRF1 bound to ITs is diffusionally mobile. This fraction strongly decreases after treatment of cells with wortmannin, a protein kinase inhibitor, and this drug also increases the frequency of chromosome aberrations.