Scrotal Heat Stress Induces Altered Sperm Chromatin Structure Associated with a Decrease in Protamine Disulfide Bonding in the Stallion

A variety of testicular insults can induce changes in the structure of spermatozoal chromatin, resulting in spermatozoal DNA that is more susceptible to acid-induced denaturation. The degree of change in the DNA can be measured using the sperm chromatin structure assay (SCSA). The SCSA measures the...

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Bibliographic Details
Published in:Biology of reproduction 1999-03, Vol.60 (3), p.615-620
Main Authors: LOVE, C. C, KENNEY, R. M
Format: Article
Language:English
Subjects:
Animals
Biological and medical sciences
Chromatin - chemistry
Chromatin - ultrastructure
Disulfides - metabolism
DNA - analysis
DNA - chemistry
Female
Fundamental and applied biological sciences. Psychology
Horses
Hot Temperature
Male
Mammalian male genital system
Morphology. Physiology
Nucleic Acid Denaturation
Protamines - metabolism
Scrotum - cytology
Spermatozoa - ultrastructure
Vertebrates: reproduction
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Summary:A variety of testicular insults can induce changes in the structure of spermatozoal chromatin, resulting in spermatozoal DNA that is more susceptible to acid-induced denaturation. The degree of change in the DNA can be measured using the sperm chromatin structure assay (SCSA). The SCSA measures the relative amounts of single- and double-stranded DNA after staining with the metachromatic dye, acridine orange. Here we used a stallion model (n = 4) to study the effects of scrotal heat stress on spermatozoal DNA. This model was created by insulating stallion testes for 48 h and collecting sperm daily thereafter for 60 days. Changes in the SCSA were then correlated with protamine disulfide content and protamine types and levels. Results of the SCSA indicated that the susceptibility of spermatozoal DNA to denaturation was dependent on the spermatogenic cell stage that the ejaculated sperm was in at the time of the heat stress. Spermatozoa with altered DNA had a decrease in the extent of disulfide bonding that was associated with an increase in the susceptibility of DNA to denaturation. However, there were no detectable changes in either the protamine type or level. Thus, in this model, decreased disulfide bonding is associated with an increased susceptibility of spermatozoal DNA to denaturation in the absence of protamine changes.
ISSN:0006-3363
1529-7268
DOI:10.1095/biolreprod60.3.615