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Interactions of Multiple Dynein Motors Studied Using DNA Scaffolding
Published in Keiko Hirose, Handbook of Dynein, 2019
Investigations of opposing motors are often conducted in the context of cargo hauling and the tug-of-war resulting from co-localized opposing motors on the same cargo. However, an essential component of motor function in vivo is the arrival of motors to the “start” of their respective microtubule tracks, which may be mediated by motor-motor interactions without the involvement of other cargo [60]. Such interactions occur in the “delivery” of dynein to the plus end of the microtubule where, in yeast, it will bind the cell cortex for positioning the mitotic spindle apparatus [8].
Nitric oxide mediated regulation of ascorbate-glutathione pathway alleviates mitotic aberrations and DNA damage in Allium cepa L. under salinity stress
Published in International Journal of Phytoremediation, 2023
Priyanka Prajapati, Praveen Gupta, Ravindra Nath Kharwar, Chandra Shekhar Seth
Salinity affects physiological and biochemical parameters but its effects at chromosomal levels are not well explored. Roots are most sensitive and remains in direct contact with abiotic stress factors. Salinity stress is shown to inhibit root growth in plants by causing mito-depressive effects and nuclear abnormalities (Saha et al., 2015; Singh and Roy, 2016; Kiełkowska et al. 2017; El-Araby et al. 2020). Hence, salinity stress can be considered as a positive control to study mutagenic effects in root cells. Moreover, damage extent depends upon plant species, genotype, salinity concentration, and exposure time. In present study, dose-dependent decline in mitotic index along with enhancement in chromosomal aberrations (as chromosomal breaks or clumping, laggard chromosomes, anaphase bridge, vagrant chromosomes, disturbed anaphase, and binucleated cells with distorted nuclei) were observed in root meristematic cells exposed to different salinity level (Figure 3). However, chromosomal aberrations were lacking in root tip cells germinated under control and SNP alone treatments. Accurate chromosomal segregation in mitosis is an error-prone stochastic process that requires attachment of sister kinetochores to microtubules (Çavuşoğlu et al. 2019). Therefore, in present study, mitotic irregularities such as disordered metaphase and anaphase resulted from spindle dysfunction triggered by excess ROS generated under salinity stress. The presence of chromosome stickiness could be result of improper folding of chromatin fibers, while chromosome laggards might occur due to abnormal spindle apparatus organization (Tabur and Demir 2009; Çavuşoğlu et al. 2019). Besides, chromosome bridges, chromosome breaks, and fragmentation could have occurred due to DNA damage and/or failure of DNA damage repair mechanisms under salinity stress. Moreover, micronucleated cells are formed due to inability of entire chromosomes or chromosome fragments incorporation in nucleus (Kiełkowska 2017). Further, nuclear deformation and degradation caused by cellular dehydration resulted in distorted nuclei (Tabur and Demir 2009). Lyu et al. (2020) reported that abiotic stress induced cytotoxic and genotoxic effects in A. cepa are mainly attributed to differential expression of genes associated with DNA replication (ORC5 and MPK5) and DNA repair (POLD1). Our reports favor that salinity declines mitotic index and induces chromosomal aberration in A. cepa (Singh and Roy 2016), Hordeum vulgare (Tabur and Demir 2009), and Pisum sativum (El-Araby et al. 2020). Under normal conditions, dividing or rapidly elongating root cells usually maintain low cytoplasmic Na+ and Cl− concentrations (Munns and Tester 2008).