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Genetics of mammalian meiosis
Published in C. Yan Cheng, Spermatogenesis, 2018
In addition to SC proteins, cohesins are essential components of the axial/lateral elements. The cohesin complex is required for sister chromatid cohesion in both mitosis and meiosis. The mammalian mitotic cohesin complex consists of two structural maintenance of chromosome (SMC) proteins (SMC1 and SMC3) and two non-SMC subunits (RAD21 and STAG1 or STAG2). Four meiosis-specific paralogues of mitotic cohesins have been identified in mammals: REC8,5,38 RAD21L,39–41 SMC1B,42 and STAG3.43 REC8 and RAD21L are homologous to RAD21. SMC1B bears sequence similarity with SMC1. STAG3 replaces STAG1/STAG2 in meiotic cohesin complexes. All these meiosis-specific cohesin proteins localize to the axial elements. Strikingly, absence of REC8 leads to synapsis between sister chromatids, suggesting that one of the main functions of REC8 is to limit synapsis to homologous chromosomes.38,44 Genetic and cell biological analyses have shown that these meiosis-specific cohesins regulate the axial element formation, axis length, sister chromatid cohesion, and meiotic recombination.45,46
Anticlastogenic and hepatoprotective effects of Kolaviron on sodium valproate-induced oxidative toxicity in Wistar rats
Published in Egyptian Journal of Basic and Applied Sciences, 2021
Olaniyi Solomon Ola, Kayode Ezekiel Adewole
VPA treatment was reported to cause significant nuclear alterations in normal drug-filtering organs like liver and diminution of some members of the structural maintenance of chromatin (SMC) proteins, SMC-associated proteins, DNA methyltransferase and heterochromatin proteins [62,63]. Findings implicated LPO in DNA damage since many of its products do interact with DNA to induce oxidative DNA damage [64]. More importantly, genotoxicity has been associated with the generation of free radicals [65]. VPA-associated genotoxicity and increase in chromosomal aberration rates have been reported by several authors both in animal models and human population [66–68]. The potential of Kolaviron to prevent vaproic acid genotoxicity using percentage DNA fragments in liver and induction of micronucleated polychromatic erythrocytes as biomarkers was investigated. MN assay is commonly used to determine the genotoxic tendency of myriads of chemicals and antigenotoxic activity of many substances. In this current work, valproate treatment increased the percentage DNA fragmentation in the liver of rats and the occurrence of polychromatic micronucleated cells in bone marrow cells, which suggest that the drug might have induced DNA strand breakage and chromosomal breakage. Kolaviron has earlier been shown to elicit protective effect against the formation of DNA strand breaks and oxidized bases in drug-induced hepatotoxicity [69]. The result of this study clearly indicated that Kolaviron has protective effect against VPA – induced genotoxicity as revealed by the reduced percentage DNA fragmentation and lower frequency of the occurrence of mPCEs in animal group co-administered with Kolaviron. The geno-protective effect of Kolaviron may be through its antioxidant mechanism.