Sperm chromatin

Citation
G. Fuentes-mascorro et al., Sperm chromatin, ARCH ANDROL, 45(3), 2000, pp. 215-225
Citations number
69
Language
INGLESE
art.tipo
Article
Categorie Soggetti
da verificare
Journal title
ARCHIVES OF ANDROLOGY
ISSN journal
0148-5016 → ACNP
Volume
45
Issue
3
Year of publication
2000
Pages
215 - 225
Database
ISI
SICI code
0148-5016(200011/12)45:3<215:SC>2.0.ZU;2-N
Abstract
Available data on dry and hydrated nuclear volume of mammalian spermatozoa indicate that available volume is clearly insufficient to contain sperm chr omatin packed in nucleosome-like structures. Therefore, sperm DNA-protein c omplexes must be packed differently than somatic DNA-protein complexes. Pac king of DNA in fixed, dehydrated mammalian sperm approaches the physical li mits of molecular compaction, making mammalian sperm chromatin the most con densed eukaryotic DNA known. The fundamental packaging unit of sperm chroma tin is a toroid similar to 900-Angstrom outer diameter, 200-Angstrom thickn ess, and 150-Angstrom diameter hole. Each toroid contains 60 kilobases of D NA and is linked to other toroids by uncoiled DNA stretches. The factors th at contribute to mammalian chromatin structuration are still under study. T he role of protamines in sperm chromatin condensation and nuclear shaping h as been overstressed to the exclusion of other possible factors. Chromatin organization in sperm nuclei is maintained during sperm condensation by tig ht interactions with the nuclear matrix at fixed sites, inducing the format ion of individual toroid-shaped DNA loop stuctures. Observations that abnor mal manchettes affect sperm head shape and chromatin organization inducing sterility speak about manchette importance during chromatin organization. T he presence in sperm chromatin of regions packaged in specific ways with se veral types of protamines or even with histones, indicates that nuclear sha ping and chromatin organization must be under DNA control. The structural p roperties that distinguish sperm DNA from somatic DNA may play the most imp ortant role in chromatin organization.