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1 April 2008 Immunocytochemical and Ultrastructural Analyses of the Function of the Ubiquitin-Proteasome System During Spermiogenesis with the Use of the Inhibitors of Proteasome Proteolytic Activity in the Alga, Chara vulgaris
Agnieszka Wojtczak, Maria Kwiatkowska
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Abstract

Spermiogenesis in Chara vulgaris and in animals share many common features, including exchange of nucleohistones into nucleoprotamines, remodeling and extreme condensation of chromatin, formation of flagellae and of microtubule manchette, and decrease in cytoplasm volume. In C. vulgaris, spermiogenesis is not preceded by meiosis since this alga is a haplobiont. In the present work we showed that in early spermiogenesis characterized by a significant metabolic activity of spermatids, the inhibitors of proteasomes did not visibly change their ultrastructure but significantly prolonged this process. At late stages of spermiogenesis, MG-132 and epoxomicin dramatically changed the structure of nuclei: regular fibrillar and lamellar structure of chromatin was disturbed and clusters of grains corresponding to aggresomes appeared, but the nucleus shape and cytoplasm structure were the same as in the controls. Immunocytochemical studies revealed that these inhibitors blocked disappearance of histones from nuclei while the structures corresponding to aggresomes were clusters of undegraded ubiquitinated histones, since they gave positive immunosignals indicating the presence of ubiquitin and histones.

Agnieszka Wojtczak and Maria Kwiatkowska "Immunocytochemical and Ultrastructural Analyses of the Function of the Ubiquitin-Proteasome System During Spermiogenesis with the Use of the Inhibitors of Proteasome Proteolytic Activity in the Alga, Chara vulgaris," Biology of Reproduction 78(4), 577-585, (1 April 2008). https://doi.org/10.1095/biolreprod.107.062901
Received: 16 May 2007; Accepted: 1 November 2007; Published: 1 April 2008
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KEYWORDS
aggresomes
Chara vulgaris
epoxomicin
gamete biology
MG-132
proteasomes
sperm maturation
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