The male-derived genome after sperm-egg fusion: spatial distribution of chromosomal DNA and paternal-maternal genomic association.
After fusion with an egg, the haploid genome of a mammalian sperm expands from a volume of a few cubic microns to a volume of several thousand cubic microns in a fully developed zygote pronucleus. Using fluorescent in situ hybridization we studied two aspects of the chromatin organization of the sperm-derived genome during this process in a model system involving fusion of human sperm with hamster eggs. We found that (a) from the beginning of sperm head decondensation to early pronuclear stages, the hybridization signal of a probe targeted to the satellite III heterochromatin of chromosome 1 appeared as an irregularly shaped domain. In fully developed pronuclei, the signal became a fiber as much as 20-fold more extended compared with interphase somatic nuclei. The signal appeared as a string of non-uniformly distributed "beads" with interspersed gaps. A similar spatial distribution and appearance recurred after the first cleavage division. (b) Male- and female-derived genomes assembled non-randomly on the first mitotic spindle, and continued to be sequestered from each other in the nuclei of two-cell stages.
Brandriff
B F
BF
University of California, Lawrence Livermore National Laboratory 94550.
Gordon
L A
LA
Segraves
R
R
Pinkel
D
D
D000818:Animals; D002467:Cell Nucleus / Q000502:physiology; D002878:Chromosomes, Human, Pair 1; D006224:Cricetinae; D046508:Culture Techniques; D004247:DNA / Q000378:metabolism; D005260:Female; D005306:Fertilization; D006801:Humans; D008297:Male; D008856:Microscopy, Fluorescence; D009693:Nucleic Acid Hybridization; D013094:Spermatozoa / Q000502:physiology*
D004247:DNA