Sonication Per Se Is Not as Deleterious to Sperm Chromosomes as Previously Inferred1

Abstract

Although sonication is a simple way to immobilize ("kill") spermatozoa prior to injection into oocytes, this has been thought to be destructive to sperm chromosomes. Mouse and human spermatozoa were immobilized by sonication and kept in various media for up to 2 h, then their nuclei were individually injected into mouse oocytes for the analysis of chromosomes at the first cleavage metaphase. In both the mouse and human, incidence of structural chromosome aberrations was much higher in the spermatozoa sonicated and stored in Biggers-Whitten-Whittingham medium for 2 h at 37.5 degrees C than in those stored for 5 min in the same medium. We concluded, therefore, that it is not sonication per se but a prolonged exposure of sperm nuclei to extracellular milieu that is detrimental to sperm chromosomes. The incidence of structural chromosome aberrations of mouse and human spermatozoa was significantly reduced when the spermatozoa were sonicated and stored in K(+)-rich nucleus isolation medium containing EDTA. This suggests that sperm chromosome degradation following sperm immobilization by sonication is partly due to detrimental effects of a Na(+)-rich medium and of DNase on sperm chromatin. Ideally, it should be possible to prepare artificial media that maintain the integrity of sperm chromosomes for many hours after immobilization.

Chromosome analysis of mouse one-cell androgenones derived from a sperm nucleus exposed to topoisomerase II inhibitors at pre- and post-fertilization stages

“…This idea is supported by our previous findings that severe structural chromosome aberrations were induced in mouse spermatozoa following treatment with ethanol [41] or demembranation by sonication [29].…”

“…Subsequently, each chromosome was C-banded to stain the constitutive heterochromatin, as previously described [29]. All autosomes and an X chromosome of B6D2F1 mice used in this study have a positive C-band at the Because it was impossible to perfectly detect reciprocal translocations by C-banding analysis, underestimation of this aberration type was unavoidable.…”

Chromosome analysis of mouse zygotes produced by intracytoplasmic injection of spermatozoa exposed to acrosome reaction inducing agents methyl-β-cyclodextrin and calcium ionophore A23187

“…Chromosome slides were stained with 2% Giemsa solution for 8 min. After conventional analysis to detect chromosome break, gap, ring and chromatid exchange, slides were stained using the C-banding technique to detect dicentric aberration and to distinguish between structural chromosome aberration and aneuploidy [22]. In the present study, incidence of chromosome aberrations was represented as that in zygotes, because paternal chromosome complements were not always separated from maternal ones in some chromosome preparations.…”

A novel method for detection of chromosomal integrity in cryopreserved livestock spermatozoa using artificially fused mouse oocytes

“…While the cytogenetic study of mouse spermatozoa has been extensively performed [9][10][11][12][13], the study of livestock spermatozoa is less developed. A low fertilizing capacity after in vitro maturation and the lipid contents in livestock oocytes are frequently hindrances for chromosomal analysis; as a result, research in this field has been delayed.…”

“…Mouse oocytes have not been utilized for chromosomal analysis of livestock spermatozoa, although there have been abundant studies in mice [9][10][11][12][13]. Therefore, the present study was performed to investigate the effect of oocyte volume in mouse oocyte recipients of livestock spermatozoa on the efficiency of chromosomal analysis.…”