Since its inception in 1929, Cytologia has made several significant contributions to the international community, including supporting various discoveries in Drosophila. These experiments were not only successful in D. melanogaster but also other species, such as D. virilis and D. ananassae. This is because the two founding Fly Rooms in Japan, one at Kyoto University and the other at Tokyo Metropolitan University, included these species in their evaluations. Many other Drosophila species have also been analyzed at the cytological, genetic, and evolutionary levels by various researchers from across the world with many of these findings subsequently discussed in Cytologia papers.
The chromosome number and karyotype formula of interesting five genera and six species of Araceae from Thailand were studied, including Lasia spinosa —uncommon local Thai vegetable species (2n=26, L6sm+L2st+Mm14+M4sm), Pistia stratiotes—common aquatic plant (2n=28, Lm10+Mm18), Pycnosphata palmata—rare plant endemic to Laos and Thailand (2n=26, Lm12+L4sm+M6m+M2sm+M2st), Scittomaglottis calyptrata—rare plant in Thailand (2n=26, Lm6+L2sm+Mm6+Msm12), Typhonium glaucum—rare plant endemic to Thailand (2n=24, Lm6+Mm4+M6sm+Sm4+S4sm), and T. trilobatum—common Thai medicinal plant (2n=18, Lsm2+L6st+Mm2+Sm8). Satellites in karyotypes of Py. palmata, S. calyptrata, and T. glaucum were observed. The symmetry karyotype formula is reported in four species, while the asymmetry karyotype formula is found in two species. The somatic chromosome numbers of two species are recorded for the first time and five species have never had their karyotypes studied previously. The NF of all species is reported for the first time. The somatic chromosome numbers, NF, karyotype formulae, and satellites in this study can be used for identification.
Progress in protein labeling by gene fusion with fluorescent protein-encoding genes and microscopic apparatuses, such as a confocal laser-scanning microscope, has enabled time-lapse analysis of meiotic chromosome movement in living plant cells. Here, we constructed the pAtDMC1:H2B:GFP fusion gene and introduced it into Arabidopsis thaliana. Whole-genome sequencing confirmed the insertion of the fusion gene into a locus between AT3G14830 and AT3G14840. The expression of the fusion gene was not specific to meiocytes but was significant in pollen mother cells (PMCs) within anthers; thus, when PMCs were extruded from anthers for direct observation, meiotic chromosomes (e.g., thin thread-like chromosomes at leptotene or synapsed homologous chromosomes at pachytene) were detected. Further, when intact PMCs inside the anthers were analyzed over time, we observed dynamic movement and conformational changes in the PMC chromosomes, and PMCs proceeded from the premeiotic interphase to anaphase II. GFP-tagged histone H2B controlled by the AtDMC1 promoter was incorporated into meiotic chromosomes normally and stayed at least partially in chromosomes until anaphase II.
The chromosome numbers and karyotypes of five species of the genus Bellevalia distributed in Turkey were analyzed. These taxa are B. anatolica B. Mathew & Özhatay, B. fominii Woronow, B. kurdistanica Feinbrun, B. rixii Wendelbo, B. turcica Pınar & Eroğlu. Three of them (B. anatolica, B. rixii and B. turcica) are endemic in Turkey. The chromosome numbers of all studied taxa were determeined as 2n=2x=8. Haploid chromosome lengths varied from 57.78 µm (B. fominii) to 68.17 µm (B. anatolica) among species. Karyotype analysis showed that Bellevalia taxa generally have median (m), submedian (sm), and subterminal (st) chromosomes, but not subterminal chromosomes in B. fominii species.
Comprehensive studies on meiotic behavior and pollen biology of a species are crucial for its conservation strategies. The presence of meiotic bottlenecks directly or indirectly influences the reproductive success of a plant species. The present study records chromosome number, male meiotic behavior, seed set, pollen viability, and pollen germination in two populations of Swertia thomsonii, an important medicinal plant of Himalaya. The chromosome count recorded in both accessions was 2n=2x=26, however; chromosomal abnormalities (21.23 and 4.31%) were recorded in population 1 (Pop-1) and population 2 (Pop-2), respectively. These include chromosomal stickiness, out of the plate, formation of laggards, abnormal spindles, bridges, multipolarity, and polysporads. These meiotic irregularities compromise pollen viability, pollen germination, and seed set of species. The possible cause for these recorded meiotic abnormalities was cold stress as the species grows in temperate or sub-alpine regions with cold climatic conditions. Another possible reason might be the presence of heavy metals in the soil more than permissible limits, which was determined by soil sample analysis. Therefore, these findings along with other reproductive and ecological studies can aid in the development of successful conservation and management strategies for this medicinally important plant species.
The genus Pterospermum Schreb. (Malvaceae) with 54 species worldwide and it is represented by 11 taxa in India. Pterospermum reticulatum Wight and Arn. is listed as vulnerable B1+2c species by IUCN. The mitotic chromosome number 2n=38 and karyomorphology of P. reticulatum are reported for the first time. The karyotype formula is 18 m+1sm and belongs to 2B karyotype of the Stebbins category.
The genus Allium L. is in Amaryllidaceae family with approximately 900 species distributed worldwide. The key aim of this study was to examine variations among eight Iranian endemic Allium species based on genome size. The results showed that among eight Allium species examined, seven were diploid (A. sativum, A. stipitatum, A. fistolosum, A. umbellicatum, A. lenkoranicum, A. stamineum, and A. rubellum; 2n=2x=16). Interestingly, the chromosome number 2n=3x=24 was evidenced in A. atroviolaceum. Strong interspecific diversity was identified in the studied Allium genome size. The overall average genome sizes of examined species were 34.17 pg, varying from 22.24 pg in A. fistolosum to 43.80 pg in A. stipitatum. The positive and significant correlations between genome size and total chromosome volume (TCV), altitude, and latitudes indicate that the species with larger genome sizes were situated in higher sea levels and low latitudes areas. These results may provide suitable information for Allium evolutionary, genetics, and breeding studies.
An enzymatic maceration and Giemsa staining method was used to compare the karyotypes of Crotalaria laburnifolia (trifoliate) and C. spectabilis (simple leaves) species belonging to distinct morphological sections and with different degrees of floral specialization. Both taxa share a 2n=16, asymmetric chromosome complement, and relatively similar karyotypic formulae. However, morphological differences in chromosome-SAT, chromosome sizes, and other related parameters stand out. Although the secondary constrictions (SC) and associated satellites are located on short arms of metacentric chromosomes, their position and size are different. In C. laburnifolia, the satellites were detected on the second chromosomal pair and not on the first, as is usual in Crotalaria, representing less than half of the short arm length. In contrast, in C. spectabilis, the satellites are located on the first pair and their size occupies most of the short arm. The role of SCs as nucleolus organizing regions (NORs) was corroborated in prometaphase cells, as they were frequently observed adjacent to or even embedded in a single large nucleolus. Furthermore, the possible relationship between floral specialization and leaf morphology is discussed concerning the chromosome sizes obtained. It is confirmed that the karyotypic characterization in Crotalaria is favorable and that chromosomal diversity provides valuable information on the organization and evolution of its karyotypes.
Five rare species from Thailand in the genus Amomum, Meistera, and Wurfbainia belonging to the tribe Alpineae, subfamily Alpinoideae, and family Zingiberaceae were cytologically studied. Chromosome numbers of all species were 2n=50. The karyotypes of all species are provided, namely Amomum repoeense Pierre ex Gagnep. (karyotype formula=22m+18sm+10st), Meistera koenigii (J.F.Gmel.) Skornick. & M.F.Newman (32m+12sm+6st with two satellite chromosomes), Wurfbainia schmidtii (K.Schum.) Skornick. & A.D.Poulsen (30m+8sm+12st), W. uliginosa (J.Koenig) Giseke (22m+20sm+8st) and W. villosa var. xanthioides (Wall. ex Baker) Skornick. & A.D.Poulsen (20m+18sm+12st with four satellite chromosomes). All karyotypes of all species are symmetric, consisting of metacentric, submetacentric, and subtelocentric chromosome pairs. The chromosome numbers of A. repoeense, M. koenigii, and W. schmidtii were reported for the first time. The karyotypes of all five species were determined for the first time. Karyotype formulas and chromosome structures of all species can be used for the identification of species.
To discriminate allopolyploid species from their parental species in Drosera, a comparative analysis of biseriate glandular trichomes (BGTs) of D. tokaiensis and its parental species was carried out. Because accurate identification of allopolyploid species D. tokaiensis is difficult due to showing intermediate morphologies between the parental species D. rotundifolia and D. spatulata, the species confirmation of 11 strains of four Drosera species including D. anglica were performed by determining the somatic chromosome numbers first, and then, cytomorphological details of the BGTs were characterized. Except for D. anglica, the typical form of the BGT was a biseriate structure made up of three cell pairs (consisted of six cells): head part (two apical cells), stalk part (two stalk cells), and foot part (two basal cells). In D. tokaiensis and its parental species, the BGTs stained with DAPI exhibited a single nucleus in each cell. Among 16 cytomorphological BGT characters of the three species, the maximum value of the BGT width of D. spatulata was shorter than those of the minimum values of D. rotundifolia and D. tokaiensis. A canonical discriminant analysis showed that the BGTs gave a clear separation to distinguish D. tokaiensis from its parental species. In cross-validated discriminant analysis, the individual variation of BGTs robustly predicted the species of each BGT, demonstrating species specificity for simple and accurate species identification by the cytomorphological characters.
Ficus septica is a widely documented ethnomedicinal plant that locals have used in varied applications due to its antibacterial, antioxidant, antimutagenic, renoprotective, and other biological activities. The present study investigates the antimitotic and antiproliferative actions of F. septica stem bark crude ethanolic extract using onion (Allium cepa) root tip assay and yeast (Saccharomyces cerevisiae) proliferation assay. A. cepa assay showed that the F. septica stem bark crude ethanolic extract can block mitosis in onion root cells by causing spindle and chromosome damage. The extract is genotoxic based on the increasing frequency of chromosomal aberrations at higher concentrations. Mitotic anomalies observed are sticky chromosomes, vagrant chromosomes, laggard, pole deviation, and polyploidy. It also showed that the extract decreased the cell viability of the yeast cells in a concentration-dependent manner. This study revealed that F. septica stem bark crude ethanolic extract has antimitotic and antiproliferative properties in A. cepa root tips and yeasts. Further study could be performed focusing on identifying and isolating antimitotic, and antiproliferative components of F. septica stem bark and conducting biological screening using other models.
We examined the morphological changes in mitochondria, mitochondrial nucleoids (mt-nucleoids), and the actin cytoskeleton in the yeast Saccharomyces cerevisiae during the transition from anaerobic to aerobic culture by immunofluorescence microscopy, DAPI staining, and rhodamine-phalloidin staining. The cells grown anaerobically to the stationary phase contained a small number of mitochondria, 7.3 per cell on average. When cells were transferred to aerobic culture, mitochondria began to elongate within 1 h and divided into smaller spherical mitochondria within 8 h. The number of mitochondria per cell on average was 29.4 at 4 h, 52.8 at 6 h, and 71.8 at 8 h. These morphological changes in mitochondria required respiratory activity and coincided well with those of the mt-nucleoids. In addition, we found that the rapid conversion of the cortical actin patches from the large aggregates to the small patches occurred during the transition from anaerobic to aerobic culture.
Because of its importance in sugarcane breeding as a source of high productivity and adaptability, efforts made to collect, conserve and characterize Saccharum spontaneum accessions from different parts of the country. Chromosomal diversity and its correlation with characters recorded during collection in this species have been revealed through the study of 71 clones collected from Jharkhand, a state located in eastern India. A total of 11 cytotypes were identified with four euploids [2n=40 (5x), 2n=56 (7x), 2n=64 (8x), 2n=72 (9x)] and seven aneuploids (2n=54, 60, 62, 66, 70, 74, 76). Regular meiosis was observed with predominant bivalent formation except in the clone IND 17-1853 (2n=72). Univalents and meiotic abnormalities were observed in this clone. The correlation of some of the characters with somatic chromosome numbers was confirmed with the analysis of onsite data and cytological studies.
Previous chromosome information for the lower chromosome numbers 2n=14, 16, 18, and 20 in Asian Begonia are restricted to nine species in two sections Diploclinium and Platycentrum. Here we report the first chromosome counts of four species as well as reconfirmed chromosome numbers of four species in sect. Platycentrum. We found 2n=12 in B. cathcartii, the lowest chromosome number known for the genus. The number of species with lower chromosome numbers reported is increased to 13 species in sections Diploclinium and Platycentrum. Additionally, we provide the first report of karyotypes of seven species with the lower chromosome numbers in sect. Platycentrum. Based on the present results and previous chromosome reports for a total of 13 species with lower chromosome numbers, the chromosome evolution for them is discussed.
The present cytological account presents a newly detected dysploid cytotype for Costus pictus with a chromosome number of 2n=4x=28. The present finding is the first report of meiotic chromosome count for the species. Analysis of microsporogenesis reveals abnormal meiotic behavior in pollen mother cells as manifested by the presence of interbivalent connections, un-oriented bivalents, chromatin stickiness, and laggards. An abnormal meiotic course in analyzed plants seems to be responsible for the formation of sterile pollen grains (31.96%). The study proposes that x=7 may have arisen due to descending dysploidy from x=9 and, the present specimen being an introduced species for the region may be evolving for better compatibility with the new habitat.