Zinc and human sperm chromatin
1993 (English)Doctoral thesis, comprehensive summary (Other academic)
X-rny microanalysis, Sephadex® chromatography of seminal plasma and exposure of spermatozoa to sodium dodecyl sulphate (SDS), were methods used to study the zinc content of sperm chromatin, the nature of the zinc binding ligands present in seminal plasma and the stability of the sperm chromatin in whole semen samples from fertile and infertile men. Split ejaculates were used to study the same variables in different fractions of the same ejaculate.
To obtain "pure" samples of prostatic fluid ejaculates were collected from four men with agenesis of the Wolffian ducts.
Spermatozoa were obtained from the vas deferens and the ejaculates from each of four men operated on with vasectomy to study how contact between the sperm and seminal plasma might influence the eventual content of zinc in the sperm chromatin.
The relative content of zinc in sperm chromatin was extremely low in the vasal spermatozoa as compared to the content of zinc in the chromatin of the ejaculated spermatozoa. This indicates that sperm may take up zinc from the seminal plasma. Another role for zinc in seminal fluid could be to prevent loss of zinc from the spenn chromatin of ejaculated spermatozoa.
The proportion of sperm heads which remained stable after exposure to SDS was found to be related to the relative content of zinc in the sperm chromatin. The content of zinc in spermatozoa from fertile men corresponded to one zinc atom per protamine molecule in the chromatin.
The relative content of zinc in the sperm chromatin had no simple relation to the zinc concentration in the seminal plasma. It was, however, found that men with a relative low content of zinc in the sperm chromatin had a disturbed sequence of ejaculation. They ejaculate the majority ofspennatozoa in an ejaculate fraction with a high admixture of seminal vesicular fluid. These fractions had a low zinc/fructose molar ratio i e a low ratio between prostatic derived zinc and vesicular derived fructose. Furthermore in these fractions seminal plasma zinc was to a high degree OOund to high molecular weight ligands (Zn~LnMw).
The low molecular weight zinc binding ligand (Zn-LLMW) was shown to be of prostatic origin and identical to citrate.
Sperm samples derived from fertile semen donors (n=5) a had a' higher proportion of sperm heads remaining stable after exposure to SDS, as well as a higher content of zinc in the sperm chromatin as compared to samples from group of men with "unexplained" infertility (n=lO). A larger sample of men investigated because of infertility (n=ll5) was also studied. Onequarter of these men had an impaired sperm chromatin stability with less than 80 per cent stable spermatozoa. The proportion zinc bound to the ligand Zn-LIIMW varied between 2~67 per cent. It is concluded that the liquefied seminal plasma, despite a high zinc concentration, could act as a zinc~ chelating medium that could deprive spermatozoa of zinc. It was, however, not possible to predict the individual fecundity in this group of infertile men by measuring the proportion of sperm heads, which remained stable after exposure to SDS or the proportion of zinc in the seminal fluid which was bound to Zn~L'IMW. The first split~ejaculate fraction should probably be studied instead of the whole mixed ejaculate to evaluate whether spermatozoa that tentatively enter the cervical mucus have an appropriate zinc~dependent stabilisation of their chromatin.
Place, publisher, year, edition, pages
Linköping: Linköpings universitet , 1993. , 69 p.
Linköping University Medical Dissertations, ISSN 0345-0082 ; 400
National CategoryMedical and Health Sciences
IdentifiersURN: urn:nbn:se:liu:diva-28591Local ID: 13745ISBN: 91-7870-942-3OAI: oai:DiVA.org:liu-28591DiVA: diva2:249402
1993-11-12, Patologens föreläsningssal, Universitetssjukhuset, Linköping, 09:00 (Swedish)
Afzelius, Björn, Professor
Papers, included in the Ph.D. thesis, are not registered and included in the posts from 1999 and backwards.2009-10-092009-10-092012-07-23Bibliographically approved