Chromosome Pairing and Fertility in Polyploids
Christopher B. Gillies in Fertility and Chromosome Pairing: Recent Studies in Plants and Animals, 2020
Polyploidy is the presence in cells or tissues of an organism of three or more copies of the basic set of chromosomes (the haploid genome). Occasional polyploid cells occur in many types of tissues in both plants and animals. Many important crop plants are polyploid, and polyploidy has undoubtedly been important in the evolution of many plants and probably some animals. More than one third of angiosperms are polyploid1 and 70 to 80% may have polyploidy in their ancestry. In contrast, polyploidy in sexually reproducing animals is rare. The usual explanation advanced is that polyploidy would disturb the sex chromosome balance, leading to intersexes,2,3 but this is not always the case. Nevertheless, approximately 10% of human zygotes are polyploid, although most spontaneously abort and the rare liveborns do not survive long.4,5 Sexually reproducing polyploid species do occur naturally among the amphibia6,8 and fish,9,10 but polyploidy in animals is often associated with parthenogenic reproduction, e.g., amphibia, fish, reptiles,11 nematodes,12,13 earthworms,14 and insects.15
rDNA: Evolution Over a Billion Years
S. K. Dutta in DNA Systematics, 2019
The rRNA genes of wheat (T. aestivum cv. Chinese Spring) are located mainly on chromosomes 1B and 6B with a minor site located on chromosome 5D81,82 (Figure 5). Although the rDNA is located in the distal one half to one third of the respective chromosomes, the genetic distance (determined by recombination frequency of the rDNA) from the centromere is very small (6B examined in detail83). Estimates for the numbers of rRNA genes on chromosome 1B range from 1300 to 1500, 6B from 500 to 3000, and 5D from 130 to 400 depending on the wheat variety considered.84,438 In T. aestivum cv. Chinese Spring there are no detectable rRNA genes on chromosome 1A,81 although in T. aestivim ssp. spelta this chromosome is a major location for rRNA genes.85 Quantitative variation in rRNA gene numbers in wheat and related grasses is also evident from heterozygosity observed in situ hybridization experiments using radioactive probes, where grain counts consistently indicate differences between homologous sites.85 Within the genus Triticum, most diploid and tetraploid species have two chromosomal locations for rDNA,86,89 and in specific cases such as T. araraticum,90T. dicoccoides,91 and T. speltoides92 these sites have been designated 1B and 6B. The homologous group 5 chromosomes also carry ribosomal DNA in some diploid Triticum species.89,92 Among hexaploid wheats as many as four chromosomal locations have been found.87
The Reproductive Systems of Davidson’s Plum (Davidsonia jerseyana, Davidsonia pruriens and Davidsonia johnsonii) and the Potential for Domestication
Yasmina Sultanbawa, Fazal Sultanbawa in Australian Native Plants, 2017
Polyploidy is prominent among many cultivated crops and is possibly present in D. johnsonii, although further investigation is needed to confirm this. The importance of polyploidy in crop improvement is well recognised (reviewed by Paterson, 2005; Udall and Wendel, 2006) and often aimed for inbreeding programmes. This is because polyploidy can generate novel phenotypic variation and adaptive plasticity, both of which are beneficial traits for domestication (Olsen and Wendel, 2013). Other potential benefits of polyploidy include genome ‘buffering’ against deleterious mutations, increased allelic diversity and increased or fixed heterozygosity (Udall and Wendel, 2006). Among the many polyploid crops, the more prominent examples include sugarcane, potato, cotton, banana, wheat and strawberries.
Evaluation of the genetic structure of Bromus inermis populations from chemically and radioactively polluted areas using microsatellite markers from closely related species
Published in International Journal of Radiation Biology, 2022
Elena V. Antonova, Marion S. Röder
The awnless brome (smooth brome, Russian bromegrass, Bromopsis inermis Leyss. = Bromus inermis Leyss., ITIS No. 40502), is a polymorphic species of the Poaceae family (Williams et al. 2011). Bromus inermis is widespread in different climatic areas of Europe, Asia and America (Bánki et al. 2021). It is a perennial, polycarpic, valuable forage plant, widely used in grassland and field grass cultivation, as well as in the fight against soil erosion (Himmelbauer et al. 2009). For this species, octoploid (genome AAAAB1B1B2B2, 2n=8x=56), hexaploid (2n=6x=42), and tetraploid (AABB, 2n=4x=28) forms have been described (Tuna et al. 2004). According to our data (Antonova et al. 2020), the studied brome populations are represented by octoploids.
EloA promotes HEL polyploidization upon PMA stimulation through enhanced ERK1/2 activity
Published in Platelets, 2022
Lanyue Hu, Weiwei Zhang, Zheng Xiang, Yali Wang, Cheng Zeng, Xiaojie Wang, Chengning Tan, Yichi Zhang, Fengjie Li, Yanni Xiao, Luping Zhou, Jiuxuan Li, Chun Wu, Yang Xiang, Lixin Xiang, Xiaomei Zhang, Xueying Wang, Wuchen Yang, Maoshan Chen, Qian Ran, Zhongjun Li, Li Chen
To test the functions of EloA in megakaryopoiesis, we first investigated the endogenous expression of EloA in the erythroleukemia cell lines. As shown in Figure 1a, compared with bone marrow stromal cells (MSCs) and stromal cell-derived osteosarcoma cell-line U2OS, EloA was more abundant in the erythroleukemia cell lines HEL and K562. Next, a shRNA targeting EloA (shEloA) was constructed in lentivirus and used to inhibit the EloA expression in HEL cells (Figure 1b,c). Upon the PMA stimulation, typical low ploidy (2 N-4 N) and high ploidy (≥8 N) HEL cells were distinguished by Hoechst 33342 staining. Then, we showed that the inhibition of EloA in HEL cells can decrease the proportion of polyploidy (≥8 N) cells from 19.1% to 7.83% (Figures 1d,e). These results indicate that knockdown of EloA impaired the HEL polyploidization.
Effects of resistance training on liver structure and function of aged rats
Published in The Aging Male, 2018
Ricardo Aparecido Baptista Nucci, Ana Caroline de Souza Teodoro, Walter Krause Neto, Wellington de Assis Silva, Romeu Rodrigues de Souza, Carlos Alberto Anaruma, Eliane Florencio Gama
Exercise increases oxygen consumption and reactive oxygen species (ROS) generation and, therefore, can enhance oxidative damage to nucleic acids in cells [25–28]. On the other hand, it has been well recognized that regular physical activity has health benefits such as reducing risk and progression of cardiovascular diseases, type 2 diabetes mellitus, cancer and neurodegenerative diseases [25,29–31]. Paradoxically, these diseases are suggested to be induced and exacerbated by ROS [25]. Additionally, Oliveira et al. [32] showed that animals submitted to aerobic exercise had the lower percentage of polyploids nuclei. Polyploidy results from incomplete mitotic cycles, which is tightly related to the aging process [32–34]. Our results in Figure 3 showed that the number of hepatocytes nuclei per field (NNH per field) were higher in animals submitted to RT, suggesting that exercise increase hepatocytes mitotic cycles increasing its numerical density and maintaining its area across age. These results may be related to the protective effect of regular exercise even on hepatic cells.
Related Knowledge Centers
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