The latest issue of Cytologia (Vol. 85, Issue 2) includes a regular paper on the long-awaited karyotype analysis of the primitive red alga, Cyanidioschyzon merolae 10D, by Kuroiwa et al. (2020) and a technical note by Miyagishima and Fujiwara (2020) introducing a method to induce a controllable gene expression system in C. merolae. In recent years, Cytologia has focused on introducing the latest research on microalgae and has published excellent papers, such as the two mentioned above. An analysis of worldwide trends in microalgae research based on a bibliometric study found that the number of published papers has increased exponentially since 1990 and 2008. The most relevant journals in this field are “Bioresource Technology” and “Algal Research.” Similarly, the number of papers in Cytologia is increasing steadily. Much interest is focused on Chlorella and Chlamydomonas. The major keywords appearing in more than 1,000 articles are those related to microalgae culture, such as “biomass,” “biofuels,” “lipids,” and their applications, or methodologies such as “bioreactor.” Today, microalgae are attracting attention (i) as sources of high-value compounds such as carotenoids, polyunsaturated fatty acids and phycobiliproteins, (ii) as whole biomass used as ingredients for food and feed, (iii) as extracts or processed biomass to produce biofuel and biofertilizers, and (iv) for bioremediation to ameliorate wastewater, soil, and polluted smoke. In this paper, we focus on how algae and microalgae are treated in Cytologia.
The analysis of chromosome polytenization in the nuclei of autopolyploids may help to determine how polyploidy affects plant growth. We performed fluorescence in situ hybridization (FISH) analysis with a centromeric DNA probe on diploid and synthetic autopolyploid series (tetraploid, hexaploid, and octaploid) of Arabidopsis thaliana to observe and quantify chromosome polytenization in polyploid plants. Our FISH analysis revealed that the number of signals of centromeric sequence was smaller than the number of chromosomes in the nuclei of basic genomes in polyploid strains, which indicates the polytenization of chromosomes. In addition, the degree of chromosome polytenization increased as the degree of ploidy increased. This result suggests that the suppression of cell proliferation in polyploid plants may be related to chromosome polytenization. The FISH analysis confirmed that chromosome polytenization occurred in the nuclei of endoreduplicated cells in all strains. We also demonstrated that the degree of polytenization increased according to the endoreduplication level. In particular, chromosomes in the nuclei of endoreduplicated octaploid cells were highly polytenized, which is likely related to the severe growth suppression observed in these cells. This is the first report to explicitly show that chromosome polytenization occurs not only in the nuclei of endoreduplicated cells but also in those of non-endoreduplicated cells (cells with a basic genome) in autopolyploid plants.
Clerodendrum inerme is traditionally used for the treatment of various diseases including cancer. The present study aimed to analyze colchicine like metaphase (c-metaphase) and cell cycle delay-inducing effects of the leaf aqueous extract of C. inerme (LAECI) in onion root tip cells. Onion root growth retardation, mitotic index reduction, decreased anaphase, and telophase cumulative frequencies were analyzed for LAECI induced cell cycle delay. The LAECI (1–8 mg mL−1) induced a concentration-dependent onion root growth retardation (p＜0.01), increased c-metaphase frequency at 4 h treatment, and 4 h treatment +16 h recovery in water. The LAECI could induce a reduction rate of transition from metaphase to anaphase, decreased percentage of anaphase-telophase cumulative frequency, root tip swelling and that was comparable with the colchicine action. In summary, LAECI contains secondary metabolites having c-metaphase and cell cycle delay-inducing effects in onion root tip cells.
The chromosome number and karyotype analysis of ten taxa of genus Tanacetum found native to Turkey were examined in detail. Somatic chromosome numbers were determined as follows: 2n=18 in T. balsamitoides Sch.Bip., T. parthenifolium Sch.Bip., T. zahlbruckneri (Náb.) Grierson, T. densum (Labill.) Sch.Bip. ssp. laxum Grierson, T. densum (Labill.) Sch.Bip. ssp. amani Heywood, T. argenteum (Lam.) Willd. ssp. argenteum, T. tomentellum (Boiss.) Grierson, 2n=36 in T. nitens (Boiss. & Noë) Grierson, T. polycephalum Sch.Bip. ssp. argyrophyllum (K.Koch) Podlech, T. abrotanifolium (L.) Druce. It was observed that chromosomes of Tanacetum taxa, of which karyotype analyses were examined, have generally median (m), submedian (sm), and rarely median point (M), subterminal (st) centromeres. In T. parthenifolium, T. nitens, T. abrotanifolium and T. argenteum ssp. argenteum; one pair of satellite chromosomes was observed.
In 2012, we discovered a unique microorganism (Parakaryon myojinensis) that has intermediate cellular structures between prokaryotes and eukaryotes from the deep sea off the coast of Japan. Observations of ultrathin sections of deep-sea specimens with electron microscopy often revealed bacteria that contained intracellular bacteria. Here, we carried out a three-dimensional analysis of one bacterium that contained several bacteria within its cytoplasm by serial ultrathin sectioning electron microscopy of freeze-substituted specimen. We found that the host bacterium was not intact and the cell wall was broken; hence, the bacteria found inside of the host were not endosymbionts, but happen to be associated independently within cytoplasm of dead bacteria. This study emphasizes the importance of 3D analysis for understanding the interactions of microorganisms.
Commelina benghalensis L. is a diploid plant with 2n=2x=22 median size chromosomes. Gamma irradiations (10, 15, 20, 25 kR) to C. benghalensis seeds induced 14 translocation heterozygotes. The translocation heterozygotes exhibited the formation of either a ring or a chain of four chromosomes in PMCs (ranged from 79.84 to 100%). The translocation lines showed the preponderance of ring quadrivalents as compared to chain quadrivalents. After comparative analysis, the quadrivalents frequently displayed alternate disjunction (52.91%) than adjacent disjunction (47.09%). At anaphase I/II and telophase I/II, the translocation heterozygotes showed the presence of lagging chromosomes and chromatin bridges. Micronuclei were sometimes formed in tetrads. Heterozygous plants showed high pollen sterility (ranged from 21.30 to 81.82%) due to the presence of adjacent orientation in quadrivalents and the cumulative effect of other meiotic irregularities. Also, pollen sterility showed a positive and significant correlation (r2=0.7285) with adjacent segregation of quadrivalents (ranged from 20.0 to 74.22%) in translocation heterozygotes.
The current study aims to contribute to the further karyological knowledge of the very diverse species Cyclamen hederifolium. The species is represented in Greece by two subspecies, C. hederifolium subsp. hederifolium and C. hederifolium subsp. crassifolium, which are not widely accepted as taxonomically distinct taxa. The subspecies are analyzed karyologically and morphometry of the most important karyological features is used to compare them, attempting to reveal the taxonomic relationships between the two subspecies. However, the karyological analysis proved that all karyotypes are symmetrical and both subspecies have both diploid and tetraploid populations. The applied karyomorphometry and multivariate analysis provided no special pattern and it was unable to differentiate the subspecies from a karyological point of view.
We report on polyploidy, karyotypes, and cytogeographical distribution of two species of native agamospermous Taraxacum in Japan. Taraxacum venustum had two polyploid numbers of 2n=3x=24 and 2n=4x=32. Four karyotypes were found in tetraploid plants. In T. shikotanense, there were seven chromosome numbers: 2n=47 (hypohexaploid), 48 (hexaploid), 56 (heptaploid), 64 (octoploid), 72 (nonaploid), 80 (decaploid), and 88 (undecaploid). Our study reveals that some races in both T. venustum and T. shikotanense can be differentiated according to their polyploidy and karyotypes.
In this study, the antimutagenic effect of Rosa canina (rosehip) infusion against to mutagenic effect of the herbicide linuron was investigated on meristematic root cells of Allium cepa (onion) by Allium test and flow cytometry method. In this context, firstly, roots of A. cepa were treated with 0.1 mg mL−1 linuron for 12 and 24 h. Then the roots were recovered by R. canina infusion for 12 and 24 h. In a result of Allium test, depending on the exposure time of linuron, it was determined linuron suppressed to mitosis in meristematic root cells and caused disturbed chromatin, sticky chromosomes, c-metaphase, chromosome bridges, vagrant chromosome abnormalities in meristematic root cells. In addition, linuron was found to inhibit DNA synthesis in S-phase of the cell cycle with flow cytometric analysis. On the other hand, it was found that the infusions of R. canina have activated DNA synthesis, arranged mitotic cell division, and reduced chromosomal abnormalities of linuron. Thus, protective effect and healing of the negative effects in mitotic cells of R. canina infusions against to the linuron toxicity on cell division was revealed.
Due to urbanization and industrialization, heavy metals have become the common environmental pollutant throughout the world. Chromosomal studies are one of the important tools to estimate the genome damaging property of these metals. This research was done to analyze the genotoxic effects of metals such as cadmium (Cd), nickel (Ni), mercury (Hg), lead (Pb) and copper (Cu) in mung bean (Vigna radiata) root tips. The experiment was set in such a way that mild metal treatment (0.01 mM) was given before respective high metal treatments (0.1 and 0.5 mM) separately, with the aim to know whether low/mild metals can alleviate metal tolerance in mung bean seedlings. Results demonstrated that metals treatment resulted in growth and mitotic index reduction. Among all the tested metals, Cd was found to cause more negative effect on growth of mung bean seedlings with length of 6.12 cm and 13.41% mitotic Index (MI) with the highest total aberrations (27.91%) at 0.5 mM Cd. Positive correlation was found between mitotic index and seedling length while a negative correlation was recorded between chromosomal aberrations with mitotic index and seedling length. Among these abnormalities C-mitosis, sticky chromosomes, and disturb metaphase were the most common aberrations irrespective of the metal. Furthermore, it was also observed that seed priming with respective mild metal concentration improves the seedling length, MI, and reduces the effect of metal stress by lowering the chromosomal aberrations in both 0.1 mM and 0.5 mM concentrations as compared to metal stress alone.
Endoreduplication is a variant of the cell cycle in which DNA replication occurs without mitosis. The physiological role of endoreduplication in plants is, however, not yet fully elucidated. We have conducted flow cytometric analysis to investigate the effect of DNA double-strand breaks (DSBs) on endoreduplication in radish (Raphanus sativus var. longipinnatus) cotyledons, where the proportion of higher ploidy cells was increased by the treatment of DSBs-inducing agent Zeocin. To understand the microscopic details of the endoreduplication caused by the Zeocin-induced DSBs, in this study, we examined nuclear DNA content and cell size in epidermal cells of radish cotyledons after Zeocin treatment. Enlargement of the cell size and puzzled-shape of the epidermal pavement cells was compromised by Zeocin treatments. Fluorocytometric analysis showed that the nuclear DNA distribution of the Zeocin-treated epidermis was distinct from that of the untreated epidermis; that is, a frequency of the nuclei with higher ploidy in the Zeocin-treated epidermis was higher than that in the untreated epidermis. A positive correlation between cell size and nuclear DNA content was found in both Zeocin-treated and -untreated epidermis, but that in the Zeocin-treated epidermis was less relevant than that in the untreated cotyledons. These results suggest that the Zeocin-stimulated ectopic endoreduplication compromises cell expansion during epidermal cell development.
Somatic chromosome numbers were determined for 15 taxa belonging to six genera of Caryophyllaceae in South Korea, Pseudostellaria (three species), Stellaria (three species), Dianthus (one species), Gypsophila (one species), Lychnis (two species) and Silene (five species), and were compared with previously reported chromosome numbers for each genus and species. This is the first report of chromosome numbers for two species, Silene koreana (2n=24), and S. seoulensis (2n=24). Furthermore, a karyotype analysis of five Silene species indicated that the basic number were all x=12, with the following karyotypic formulas: S. aprica var. oldhamiana (2n=4x=48=48m), S. jenisseensis (2n=2x=24=20m+4sm), S. koreana (2n=2x=24=16m+8sm), S. seoulensis [2n=2x=24+ I=20m (4sat)+4sm], and S. takesimensis [2n=2x=24=20m+4sm (1sat)]. These were the first karyotype analyses for the examined taxa, except S. aprica var. oldhamiana. S. seoulensis had the most asymmetrical karyotype among these species.
Senecio hewrensis Hook.f. (Asteraceae) is one of endemic species to the India. Chromosome number and karyomorphology of the species were unknown. Thus, in present communication the somatic chromosome number and karyomorphology were described of S. hewrensis. Somatic chromosome number was observed 2n=20. Karyotype formula is 2n=20=20m. The karyotype is 1A of Stebbins category.