The nuclear pore complex is a multiprotein complex comprising approximately 30 different proteins called nucleoporins (Nups). Recent studies in yeast, animals, and plants have shown that the Nups bind to chromatin and interact with transcription factors, chromatin-remodeling factors, histone-modifying enzymes, and chromatin structural proteins, including the CCCTC-binding factor and cohesin. These findings suggest that the Nups provide a subnuclear platform for gene expression, chromatin organization, and DNA repair.
Cell segmentation from microscopic images is conventionally used to investigate cell morphology. However, the time expense for manual segmentation becomes extreme with increasing numbers of cells to be analyzed. Recent progress in automated image analysis techniques can facilitate efficient and accurate cell segmentation in wide-range confocal images. Pavement cells, which mainly comprise the epidermal tissue of plant leaves, show jigsaw puzzle-like shapes and provide a model for elucidating the mechanisms underlying the complex morphology of plant cells. This mini-review demonstrates the effectiveness of using a confocal image processing pipeline for morphometric analysis and mechanical simulation using Arabidopsis thaliana cotyledon pavement cells as an example. We examined A. thaliana cotyledon surfaces using wide-range confocal images and used an image processing pipeline in ImageJ software to extract epidermal cell contours. We then used the segmented epidermal cell images to provide examples of how this information can be used for morphometry and mechanical simulation. The use of this high-throughput segmentation method is not limited to plant epidermal tissue and can be applied to various biological materials. Therefore, our approach to microscopic image analysis will hopefully contribute to the advancement of quantitative cell morphology research.
Allium cepa assay is performed to evaluate the cytotoxicity of anti-cancerous drugs namely, Doxorubicin and Erlotinib. The doses administered are much lower than the pharmaceutical concentrations. The objective of the work is to determine the safe dose(s) of the drugs after disposal to the environment for eco-safety monitoring. Assessments of mitotic indices and cytological aberrations observed in dividing and resting cells to untreated control suggest that the doses employed are sub-lethal to lethal. Types of cytological abnormalities encountered in treated cells indicate that both the drugs are clastogenic (fragments, rings, bridges, and cells with micronucleus) apart from affecting the spindle apparatus (vagrant chromosomes and multipolarity) and cellular metabolism (stickiness of chromosomes and giant cells formation). The present results can be used as an index for safe dose(s) monitoring of the drugs for ecological safety.
“Híbrido de Timor” (HT) ‘CIFC 4106’ is a natural allotriploid formed from Coffea arabica×C. canephora, which has been used to elucidate morphogenic in vitro responses and to regenerate new individuals, owing to its resistance to coffee pathogens and its semifertile condition. However, seedlings have not been efficiently regenerated from somatic embryogenesis hitherto. This study aimed to adapt a new indirect somatic embryogenesis procedure for HT ‘CIFC 4106,’ and to evaluate the genetic stability of plantlets regenerated. Leaf explants were inoculated in semisolid (M1) and liquid (M2) media for friable calli induction. During six subcultures (three months), the semisolid system yielded more friable calli, with visually greater cell mass. Subsequently, the friable calli of the two systems were randomly transferred to semisolid (M3) or liquid (M4) media for somatic embryo regeneration. The highest somatic embryo regeneration rate was observed in M1–M4. All recovered plantlets showed stable allotriploidy. We reinforce the relevance of adjusting in vitro conditions for indirect somatic embryogenesis establishment to provide plantlets of the different Coffea germplasms. In addition, the proposed indirect somatic embryogenesis protocol in a liquid system enables the propagation of HT ‘CIFC 4106’ plantlets, overcoming the seminal propagation barriers.
Somatic chromosome numbers and karyotypes of three Murdannia species are reported here for the first time. M. assamica and M. fadeniana are endemic to India while M. striatipetala is found only in India and Sri Lanka. M. assamica has chromosome number and karyotype formula 2n=20 and 8m+1sm+1st, M. striatipetala with 2n=20 and 8m+1sm+1st, and M. fadeniana with 2n=40 and 20m. Chromosome length in somatic metaphase varies from 1.15–3.26 µm with a total length of 20.07 µm for M. assamica, 1.63–3.14 µm with a total length of 22.36 µm for M. striatipetala and 0.96–2.04 µm, with a total length of 27.75 µm for M. fadeniana. Karyological data are found useful in assessing relationship in the family Commelinaceae.
The effect of alkylating anti-cancerous drugs oxaliplatin and carboplatin were assessed on germinating seedlings of Lathyrus sativus L. Concentrations used for oxaliplatin were 1 µM, 10 µM, 20 µM and 30 µM respectively; and 100 µM, 200 µM, 300 µM and 400 µM for carboplatin. The radicle length and mitotic index decreased with the increasing concentration of the drugs. Polyploidy was induced on germinating roots by pre-treatment (8 h) with 0.5% colchicine. The inhibitory effect of the drugs on the induced polyploidy was evident with the increasing doses of the drugs. In vitro callus growth in different doses of the drugs in media was measured by taking the weight and area of the callus. The objective of the work was to assess the effectiveness of alkylating drugs on the plant-based model to develop a plant-based model system for the primary screening of anti-cancerous drugs.
The genus Diospyros L. (Ebenaceae) with 550 species worldwide is represented by 54 taxa in India. The present study deals with karyomorphological studies of D. candolleana Wight and D. melanoxylon Roxb. and reports the mitotic chromosome count (2n=30) and basic karyomorphology in endemic species D. candolleana first-time reports.
During the ontogeny of angiospermous pollen, a small generative cell (GC) detaches from the inner pollen wall (intine) and is engulfed within the cytoplasm of the pollen tube cell (PC). This engulfment process is considered to be a type of endocytosis; however, the type is currently unknown. We investigated morphological changes in the cell membrane and cell wall, and the dynamics of cell wall ingredients and cytoskeletal elements, during GC engulfment by the PC in Liriope muscari pollen. Three-dimensional imaging using field-emission scanning electron microscopy revealed that the GC membrane detached from the intine in all directions. Simultaneously, the GC became spherical, and the PC membrane progressed centripetally while covering the GC detachment area. Finally, the GC was released into the PC cytoplasm, and the exfoliated area was completely covered by the PC membrane. Immediately after microspore division, the cell wall between the GC and PC contained methyl-esterified pectin and callose, which subsequently disappeared, thereby thinning the cell wall. During GC engulfment, actin filaments were distributed throughout the PC, particularly in the GC detachment area. Myosin was distributed around the GC and granules immediately after microspore division, until the completion of GC engulfment. Cytochalasin B prevented GC engulfment. These results suggest that cell wall thinning through the degradation of pectin and callose is important in GC engulfment and that actin filaments are involved, similar to their role in endocytosis in animal cells.
A cytogenetic study using conventional surface-spread, air-dried, Giemsa-stained techniques were performed in somatic cells from six individuals of Prosopis glandulosa var. torreyana belonging to a population in northern Mexico. The results confirmed chromosome number 2n=28 and its karyotype generally consistent with that shown in other species of mimosoid whose karyotypes are characterized by a predominance of chromosomes with a medium or slightly displaced centromere and few subterminal centromeres. However, there were differences in chromosomal morphology concerning other Prosopis species involving chromosome size and the location, shape, and size of the satellites on the SAT chromosomes. The evidence of chromosomal remodeling, not previously described in this genus, favors its possible participation as a genetic isolation mechanism that would prevent the formation of viable hybrids, as has been recorded in other studies.
Hildegardia populifolia (Malvaceae) is one of the endemic and rare species of Eastern Ghats. The mitotic chromosome counts 2n=40 and basic karyomorphology of H. populifolia is reported for the ﬁrst time. The karyotype formula is 20 m. The karyotype is 1A of the Stebbins category.
Detailed knowledge about the meiotic behavior of threatened plant species is crucial to develop successful conservation strategies. Here we provide a detailed account of the male meiotic behavior of Trillium govanianum Wall ex. D. Don—an endangered endemic medicinal plant species of the Himalaya. We collected the plant material from the Bangus valley of the Kashmir Himalaya. The species showed chromosome number n=2x=10, which is the first gametophytic report for this species. The pollen fertility was found to be in the range of 88–90%. The reduced fertility was due to the meiotic abnormalities such as chromatin stickiness, a late disjunction of bivalents, chromatin bridges, formation of laggards, and polysporads with micronuclei. The seed set was found to be 65.85%. The reduced seed set might be attributed to the presence of various meiotic abnormalities observed.
Hopea ponga (Dipterocarpaceae) is a rare endemic species of Western Ghats. Meiotic chromosome count n=7, mitotic chromosome counts 2n=14 and basic karyomorphology of H. ponga are reported for the ﬁrst time. The karyotype formula is 2n=14=14m. The karyotype is 1A of the Stebbins category.
Scutellaria discolor Colebr. (Family Lamiaceae, common name: bicolor skullcap) is a traditionally used medicinal plant. The present study aimed to analyze cell cycle delay and colchicine like metaphase (c-metaphase) inducing effects of aqueous extract of S. discolor herb (AESD) in onion, Allium cepa, root apical meristem cells. Onion root growth retardation, mitotic index, dividing cell frequencies, and c-metaphase frequency were analyzed after AESD treatment. The AESD induced a concentration-dependent onion root growth retardation, increased metaphase and c-metaphase frequency, reduced subsequent transition from metaphase to anaphase, and that was comparable with the colchicine action. In summary, AESD may contain colchicine like secondary metabolites having cell cycle delay and c-metaphase inducing effects in onion root tip cells, indicating its perspective use in the field of medicine, karyotyping, and cytotoxicity studies.
Clerodendrum viscosum is a traditionally used medicinal plant. The present study aimed to analyze a detailed cytotoxic effect of the non-polar petroleum ether fraction (AQPEF) of leaf aqueous extract of C. viscosum Vent. (LAECV) in Allium cepa root tip cells. The LAECV was fractionated with petroleum ether and tested for A. cepa toxicity. Micronuclei, polyploidy, and mitotic abnormalities were analyzed after AQPEF treatment. The AQPEF induced concentration-dependent increased mitotic abnormalities, micronuclei, and polyploid cell frequency in A. cepa root tip cells and that were comparable with the colchicine effects. Thus, the present study explores that petroleum ether is a suitable solvent for extraction of the active phytochemicals of LAECV; AQPEF having colchicine like micronuclei, polyploidy and mitotic abnormality inducing potentials in A. cepa root tip cells, indicating its perspective use in karyotyping, plant breeding programs, and cytotoxicity studies.
Scadoxus multiflorus is a traditionally used medicinal plant, widespread in Sub-Saharan Africa from Senegal to South Africa and in some places of Saudi Arabia and India. The present study aimed to analyze antimitotic and cytotoxic effects of leaf aqueous extract of S. multiflorus (LAESM) in Allium cepa root apical meristem cells. The root growth retardation, mitotic index (MI), cytological and mitotic abnormalities were analyzed in A. cepa root apical meristem cells after LAESM treatment. The LAESM induced a concentration-dependent A. cepa root growth retardation, MI decreased to a large extent in the treated samples. The LAESM induced mitotic, nuclear, and chromosomal abnormalities in A. cepa root tip cells. Thus, the present work indicates for the first time antimitotic and cytotoxic potentials of leaf aqueous extract of S. multiflorus.