Cholesteric organization of DNA in the stallion sperm head.
Abstract: The fine structure of chromatin in sperm heads was investigated by different microscopic techniques: in vivo examinations in the polarizing microscope, thin sections and freeze-fracture replicas observed by transmission electron microscopy. The freeze-fractured chromatin appears to be formed of superimposed lamellae, each one 330 A thick. These lamellae are parallel to the flattening plane of the sperm head. This situation was already described in other mammal spermatozoa and in particular in the bull and the rabbit. This work presents a new interpretation of this lamellated aspect. The chromatin structure of these spermatozoa is that of a cholesteric liquid crystal. This structure resembles that of a plywood, made of superimposed layers of parallel filaments, but instead of having a right angle between two successive layers, there is a progressive rotation and similar orientation occurs at each 180 degrees rotation. The apparent lamellae result from cleavages due to freeze-fracture between levels of parallel filament orientation. The thickness of lamellae corresponds therefore to the half helicoidal pitch of the cholesteric liquid crystal. This model is consistent with our observations by polarizing microscopy. The lamellation is not visible in thin sections of stallion spermatozoa. There are however biochemical methods to decondense chromatin and we are able to observe this lamellation in sections normal to the flattening plane of sperm heads. The methods used classically to decondense the sperm chromatin lead to extremely varied aspects which are discussed, some of them being closely related to the structure of cholesteric liquid crystals.
Publication Date: 1984-01-01 PubMed ID: 6484936DOI: 10.1016/0040-8166(84)90029-6Google Scholar: Lookup
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- Journal Article
Summary
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This research investigates the complex structure of chromatin, organized like a cholesteric liquid crystal, within stallion sperm heads using multiple microscopy techniques.
Overview and Techniques Used
- The researchers looked into the detailed structure of chromatin present within the sperm heads of stallions.
- The methodology included a variety of microscopy techniques. These included in vivo polarizing microscopy, transmission electron microscopy of thin sections and freeze-fracture replicas.
Findings and Interpretation
- The freeze-fractured chromatin was observed to be composed of stacked layers or lamellae, with each layer being approximately 330 Angstroms in thickness.
- These layers were found to be in parallel alignment with the flattened plane of the sperm head, which corroborates with previous observations made in other animals including bulls and rabbits.
- The layered structure or lamellation of the chromatin is proposed by the researchers to have the structure of a cholesteric liquid crystal. This structure was compared to that of plywood, albeit with a progressive rotation between layers instead of a right angle.
- This rotation revealed a pattern in which a similar orientation was observed for every 180 degrees of rotation.
- The researchers theorize that the visible lamellae are the result of freeze-fracture cleavages between levels of parallel filament orientation and that the thickness corresponds to the half-helix pitch of the cholesteric liquid crystal.
Consistency of Findings and Future Directions
- The liquid crystal model of lamellae constructed by the researchers aligned consistently with their polarizing microscopy observations.
- Interestingly, this lamellation was not visible in thin sections of the sperm heads. However, the researchers underscore that biochemical techniques are available for decondensing chromatin to study this layered structure.
- The used methods that allow for the decondensation of sperm chromatin were found to result in diverse aspects which deserve further exploration, some of these aspects relating closely to the structure of cholesteric liquid crystals.
Cite This Article
APA
Livolant F.
(1984).
Cholesteric organization of DNA in the stallion sperm head.
Tissue Cell, 16(4), 535-555.
https://doi.org/10.1016/0040-8166(84)90029-6 Publication
Researcher Affiliations
MeSH Terms
- Animals
- Birefringence
- Chromatin / ultrastructure
- Crystallography
- DNA
- Disulfides
- Freeze Fracturing
- Horses
- Male
- Oxidation-Reduction
- Snails
- Sperm Head / ultrastructure
- Spermatozoa / ultrastructure
Citations
This article has been cited 13 times.- Ward WS. Organization of sperm DNA by the nuclear matrix. Am J Clin Exp Urol 2018;6(2):87-92.
- Brach K, Hatakeyama A, Nogues C, Olesiak-Banska J, Buckle M, Matczyszyn K. Photochemical analysis of structural transitions in DNA liquid crystals reveals differences in spatial structure of DNA molecules organized in liquid crystalline form. Sci Rep 2018 Mar 14;8(1):4528.
- Sung B, Kim MH. Liquid-crystalline nanoarchitectures for tissue engineering. Beilstein J Nanotechnol 2018;9:205-215.
- Roy S, Morse D. Transcription and Maturation of mRNA in Dinoflagellates. Microorganisms 2013 Nov 1;1(1):71-99.
- Zhu G, Hu R, Zhao Z, Chen Z, Zhang X, Tan W. Noncanonical self-assembly of multifunctional DNA nanoflowers for biomedical applications. J Am Chem Soc 2013 Nov 6;135(44):16438-45.
- Lander GC, Johnson JE, Rau DC, Potter CS, Carragher B, Evilevitch A. DNA bending-induced phase transition of encapsidated genome in phage λ. Nucleic Acids Res 2013 Apr;41(8):4518-24.
- Roy S, Morse D. A full suite of histone and histone modifying genes are transcribed in the dinoflagellate Lingulodinium. PLoS One 2012;7(4):e34340.
- Chow MH, Yan KT, Bennett MJ, Wong JT. Birefringence and DNA condensation of liquid crystalline chromosomes. Eukaryot Cell 2010 Oct;9(10):1577-87.
- Andrabi SM. Mammalian sperm chromatin structure and assessment of DNA fragmentation. J Assist Reprod Genet 2007 Dec;24(12):561-9.
- Merchant K, Rill RL. DNA length and concentration dependencies of anisotropic phase transitions of DNA solutions. Biophys J 1997 Dec;73(6):3154-63.
- Rill RL, Livolant F, Aldrich HC, Davidson MW. Electron microscopy of liquid crystalline DNA: direct evidence for cholesteric-like organization of DNA in dinoflagellate chromosomes. Chromosoma 1989 Oct;98(4):280-6.
- Ward WS, Partin AW, Coffey DS. DNA loop domains in mammalian spermatozoa. Chromosoma 1989 Sep;98(3):153-9.
- Bwanga CO, Ekwall H, Rodriguez-Martinez H. Cryopreservation of boar semen. III: Ultrastructure of boar spermatozoa frozen ultra-rapidly at various stages of conventional freezing and thawing. Acta Vet Scand 1991;32(4):463-71.
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