Simple Chromocenter Type Research Articles

Karyotype profile of holarrhena antidysenterica (Roxb. Ex fleming) wall

The karyomorphological features of Holarrhena antidysenterica (Roxb. ex Fleming) Wall. through the application of differential staining techniques (using orcein, CMA, and DAPI) were studied. After applying orcein staining, the interphase nuclei of this species exhibited a ‘simple chromocenter type’ with numerous small heterochromatin blocks and the prophase chromosomes were ‘interstitial type’. The karyotype analysis revealed that this species possesses diploid chromosome number of 2n = 22, with all metacentric chromosomes. The total length of the chromosome complement in the diploid set was 29.91 μm. A total of four CMA-positive bands were observed in this species whereas seven bands were found after DAPI-staining. Heteromorphicity was observed in the DAPI stained metaphase stage indicating the probable occurrences of chromosomal aberrations such as deletion and inversion. The karyotype profile of H. antidysenterica obtained from orcein and fluorescent banding was determined for the first time in Bangladesh. Bangladesh J. Bot. 52(4): 1085-1089, 2023 (December)

Karyotype comparison and characterization of two cauliflower cultivars from Bangladesh

Two cauliflower cultivars were karyotyped for correct characterization after orcein staining. Both cultivars have a simple chromocenter type of interphase nuclei and a gradient type of prophase chromosomes, indicating that they descended from a common ancestor. In addition, both strains were found to have 2n=18 chromosomes with an almost identical range of chromosome lengths. In terms of overall length, the white snow cultivar is almost 7 m shorter than the fresh market cultivar, indicating the presence of chromatin length diversification between specimens. In none of the cases was there a noticeable gradual decrease in chromosome length. The metacentric and submetacentric chromosomes were observed in both samples examined. Apart from other karyotypic features, TF, Syi and AsK % indicate the moderately symmetrical nature of the karyotype. As a result, the two cultivars of cauliflower were moderately primitive in nature. The collection of this karyotypic data will aid in the authentic characterization of the two cauliflower cultivars, which is essential information for the breeding program.
 Jahangirnagar University J. Biol. Sci. 11(1 & 2): 21-30, 2022 (June & December)

Heterochromatin Distribution Pattern of Six Wild Corchorus L. Species with Differential Staining from Bangladesh

In this study pattern of heterochromatin dis-tribution at mitotic interphase and prophase stage of six wild <i>Corchorus</i> L. species, viz. C. <i>brevicornatus</i>, C. <i>septentrionalis</i>, C. <i>urticifolius</i>, C. <i>hirtus</i>, C. <i>siliquosus</i> and C. <i>pinnatipartitus</i> were investigated following orcein, CMA- and DAPI- staining. After orcein staining, interphase nuclei of C. <i>brevicornatus</i>, C. <i>septentrionalis</i> and C. <i>urticifolius</i> had 'Diffuse Type' while C. <i>hirtus</i>, C. <i>siliquosus</i> and C. <i>pinnatipartitus</i> had 'Simple Chromocenter Type'. In case of prophase chromosomes, C. <i>septentrionalis</i> and C. <i>urticifolius</i> were detected as 'Gradient Type', C. <i>brevicornatus</i> and C. <i>hirtus</i> as 'Continuous Type' and C. <i>siliquosus</i> and C. <i>pinnatipartitus</i> as 'Interstitial Type'. Distinct amount of CMA- and DAPI- fluoresced bands were observed in the studied six wild <i>Corchorus</i> L. species.

Comparative study of morphology and heterochromatin distribution in three oilseed species of Brassica L.

Morphological traits and nature of heterochromatins in interphase nuclei and prophase chromosomes of three oilseed species of Brassica L. (B. campestris, B. juncea, and B. napus) have been investigated in this study for morpho-cytotaxonomical evaluation. The three Brassica species displayed morphologically differences in the case of plant heights, size and the shape of upper and basal leaves, types of inflorescence and color of seeds, etc. After analyzing the staining properties of heterochromatins (nature and amount) in the interphase nuclei, it was unveiled that B. juncea had a simple chromocenter type of interphase nuclei and might be perceived as the most evolved one among the three species of Brassica. Moreover, the phylogenetic relationship derived from the mean values of morphological traits also manifested the distinct position of B. juncea than the other two studied species of Brassica. Therefore, the findings obtained in this study may be utilized as a feasible implementation of biosystematics for the identification and proper characterization of the three species of Brassica L. J. Bangladesh Acad. Sci. 45(2); 169-179: December 2021

Orcein and Fluorescent Banding Analysis of Two Floral Types of Catharanthus Roseus L.

Two floral types of Catharanthus roseus L. viz. pink and white were studied through differential staining with orcein, CMA and DAPI for cytogenetical characterization and to assist towards updating their taxonomical status and evaluating chromosomal diversity between them. "Simple Chromocenter Type" of interphase nuclei was observed with some darkly stained small heterochromatic regions throughout the nuclei. Most of the prophase chromosomes of Catharanthus roseus (pink and white) were "Continuous Type" and a few were "Gradient Type". Although these two floral types possessed 16 metacentric chromosomes in somatic cells, they showed variation in fluorescent banding pattern considering the modification of GC- and AT-rich repetitive segments. Taking into account all the parameters of both the floral types of C. roseus showed strict symmetric karyotype as well as primitive nature. Therefore, the combined data of differential staining provide information to make comments on their chromosomal status with cytogenetical characterization and also create a baseline for future research.&#x0D; Dhaka Univ. J. Biol. Sci. 29(2): 219-227, 2020 (July)

Karyomorphological study of Enhydra fluctuans Lour. (Asteraceae)

In the present study, karyomorphological features of Enhydra fluctuans Lour. were investigated. Orcein-staining was used for the authentic chromosomal characterization and identification. In E. fluctuans ‘Simple Chromocenter Type’ of interphase nuclei was observed with many small heterochromatin blocks after orcein staining. Prophase chromosomes showed ‘Gradient Type’ with orcein staining. This species was found to possess 2n=10x=110 with basic chromosome number x=11 and this is probably the first report for this species. The centromeric formula of this species was ‘38m+70sm+2ac’. The above features indicated that E. fluctuans is an advance polyploid with asymmetric karyotype. The total chromatin length (2n) was 295.92 μm. Individual chromosome length ranged from 1.84-4.26 μm. The relative length of each chromosome ranged from 0.006-0.014. The above mentioned data will be useful for karyomorphological characterization of E. fluctuans from Bangladesh.&#x0D; Bangladesh J. Sci. Ind. Res.54(4), 283-288, 2019

Cytotaxonomy of four Floral Variants of Impatiens Balsamina L.

Karyomorphological characters were investigated in four floral variants of Impatiens balsamina L. viz. white, pink, violet and red for proper characterization and inferring relationships among them. All four floral variants of I. balsamina were found to possess 2n = 14 chromosomes, and ‘Simple Chromocenter Type’ of interphase nuclei was observed in all variants with many small heterochromatin blocks after orcein staining. ‘Continuous Type’ of prophase chromosomes was found in red variant, whereas both ‘Continuous and Gradient Type’ were found in other three variants. The red variant could easily be distinguished from the remaining three variants by total chromosome length, centromeric formula, average chromosome length, total form value, and karyotype asymmetry plus symmetry index. Based on karyomorphology, the white, pink and violet variants of I. balsamina were found very closely related and constituted with similar genome, whereas red variant was found to possess slightly modified genome and distinct from other three floral variants.&#x0D; Journal of Bangladesh Academy of Sciences, Vol. 43, No. 1, 1-9, 2019

Cytogenetical characterization of Acalypha indica L. in Bangladesh

Acalypha indica L. was cytogenetically characterized after staining with orcein, CMA and DAPI. In this species "Simple Chromocenter Type" of interphase nuclei was observed with a few small heterochromatin blocks following orcein staining. Prophase chromosomes showed “Interstitial Type” of staining pattern with orcein which indicated the tendency of aggregation of heterochromatin in interstitial regions of chromosome. This plant was found to possess 2n = 20 metacentric chromosomes. The total length of 2n chromosome complement was 55.33 μm. Individual chromosome length ranged from 1.84 to 3.50 μm. The relative length of each chromosome ranged from 0.03 to 0.06. After staining with CMA, three bright bands were observed at different locations of chromosomes. A total of four DAPI-positive bands were also found of which two bands were centromeric and other two were entirely fluoresced with DAPI. The results of the cytological investigation may be useful for future characterization of this plant species.&#x0D; Dhaka Univ. J. Biol. Sci. 27(2): 183-189, 2018 (July)

Karyomorphology of Justicia adhatoda L. by differential staining

Karyomorphological features of Justicia adhatoda L. were investigated in this study after differential staining with orcein, CMA and DAPI for proper characterization. In this species "Simple Chromocenter Type" of interphase nuclei was observed with many small heterochromatin blocks after orcein staining. Prophase chromosomes showed "Interstitial Type" of staining pattern which indicated the tendency of aggregation of heterochromatin in interstitial regions of chromosome. This species was found to possess 2n = 34 metacentric chromosomes. The total length of 2n chromosome complement was 132.17 μm. Individual chromosome length ranged from 2.57 to 5.43 μm. The relative length of each chromosome ranged from 0.02 to 0.04. A total of seven CMA-positive bands were observed in this species whereas no band was found after DAPIstaining. This result suggested the absence of AT-rich portions and occurrence of GC-rich portions in the respective banded chromosomes. Except 2n chromosome number, the other karyological and fluorescent banding information probably was the first report for this species and it might help to enhance the chromosomal data base with detailed karyomorphological information of this plant species in Bangladesh.&#x0D; Dhaka Univ. J. Biol. Sci. 27(2): 175-181, 2018 (July)

Karyomorphological Studies in Some Species of Parnassia L. (Saxifragaceae s.l.) in East Asia and Intraspecific Polyploidy of P. palustris L.

Karyomorphological information is one of the most important characters for cytotaxonomy. We described karyomorphology of 14 species of Parnassia in East Asia. They had commonly the resting chromosomes of the simple chromocenter type and the mitotic prophase chromosomes of the proximal type. The somatic chromosome number of 2n=14 was shown in three species, that of 2n=18 was shown in six species, that of 2n=18 or 36 was shown in two species, that of 2n=32 was shown in one species, that of 2n=36 or 36+1∼8 s was shown in one species, and that of 2n=18, 27, 36 or 45 was shown in one species. They were commonly monomodal (gradual) decrease in length from the largest to the smallest chromosomes. However, their absolute chromosome sizes were different from each other. Average chromosome sizes were recognized as three types small (1.21 μm), medium (1.7–2.36 μm), and large (3.1–3.75 μm). Parnassia palustris showed four cytotypes that could be likely cytogeographically correlated with habitats, polyploidy, and sizes of pollen grains.

Karyotype analysis of Santalum album L.

A karyomorphological study on Santalum album was conducted for the fi rst time. The interphase nucleus was a simple chromocenter type while the prophase chromosomes were of the interstitial type. The shoot-tip meristems of some S. album individuals were found to be mixoploid, i.e. 2n = 2x = 20 and 2n = 4x = 40. Two different karyotypes, one diploid (2n = 2x = 20) and one tetraploid (2n = 4x = 40), were also present; their karyotypic formulae were 2n = 20 = 18m + 2sm and 2n = 40 = 32m (2SAT) + 8sm, respectively. The chromosomes of both karyotypes showed centromeres predominantly in a median position and a few submedian centromeres, of 2B type, of a primitive and symmetrical nature.

Karyotypes of thirteen species ofPedicularis(Orobanchaceae) from the Hengduan Mountains Region, NW Yunnan, China

Abstract Karyotypes of thirteen species (including 3 subspecies, 2 varieties) of Pedicularis L. (Orobanchaceae) from the Hengduan Mountains Region, NW Yunnan, China were investigated. Twelve species of them were reported for the first time. The species examined all had one or other of two basic chromosome numbers: 2n=14 and 2n=16. All species investigated are diploid and share the same type of choromocenters in prophase nuclei, but differed in their interphase nuclei. The species with 2n=14 have the simple chromocenter type of interphase nuclei, while those with 2n=16 have the complex chromocenter type of interphase nuclei. These results confirm former reports, which have shown that 2n=16 is by far the most common number in this genus. Based on the karyomorphological evidence as well as morphological characters, relationships between the species studied are discussed.

A Cytological Study on three Species of Colocasia (Araceae) from Yunnan

Chromosome numbers and karyotypes of three Colocasia species from Yunnan were reported. Their karyotypes were as follows: 2n = 2x = 28 = 22m (1 sat) + 6sm for C. gongii; 2n = 2x = 28 = 20m + 8sm for C. gaoligongensis; 2n = 2x = 28 = 20m + 8sm for C. gigantea. Common karyomorphological characteristics of three species examined were: (1) the simple chromocenter type of the resting chromosomes and the proximal type of the mitotic prophase chromosomes; (2) the chromosome number 2n = 28 and (3) the chromosome complement of m- and sm-chromosomes. x = 14 was confirmed as the basic chromosome number of Colocasia. There were differences among species in the number of in- and sm-chromosomes as well as satellite.

Karyomorphological study of the Spiraea japonica complex (Rosaceae)

Reported in this paper is a karyomorphological study on one natural population of each of eight varieties in the Spiraea japonica complex. The interphase and mitotic prophase can be classified into the simple chromocenter type and the proximal type, respectively. The metaphase karyotypes of the eight varieties were formulated as follows: S. japonica van japonica: 2n = 18 = 14m + 2sm + 2st; S. japonica var. acuta: 2n = 18 1m + 4sm + 3st; S. japonica var. incisa: 2n = 18 = 12m + 4sm + 2st; S. japonica var. stellaris: 2n = 18 = 15m + Ism + 2st; S. japonica var. acuminata: 2n = 18 = 14m + 2sm + 2st; S. japonica var. ovalifolia: 2n = 18 = 10m + 2sm + 2st + 4t; S. japonica var. glabra: 2n = 18 = 10m + 4sm + 4st; S. japonica var. fortunei: 2n = 36 = 17m + 16sm + 3st. Karyomorphological study reveals that the chromosome numbers within the complex are stable, and that karyomorphological divergence between the varieties lies mainly in chromosome size and organization. Based on the karyomorphological data and geographical distribution of the complex, the differentiation pattern as well as evolutionary mechanism of the complex is evaluated.

Karyomorphology of Podocarpus s.l. in China and its systematic significance

Investigated in the present paper is the karyomorphology of 7 species in 3 sections of Podocalpus s.1. from Yunnan province of China. All species commonly showed the mitotic prophase chromosomes of the same interstitial type, but different resting nuclei type. The resting nuclei were found the gradient type for Sect. Dacrycarpus, the simple chromocenter type for Sect. Nageia and the complex chromocenter type for Sect. Podocarpus respectively. The karyotype formulae were 2n=20=16M+4SM for Podocarpus imbricatus, 2n=26=9M+17SM for P. nagi, 2n=26=17M+9SM for P. wallichiana, 2n=26=13M+13SM for P. fleuryi, 2n=38=19M+3SM+2ST+8T for P. macrophyllus var, angustifolius, 2n=38=18M+10SM+2SM+8T for P. forestii, and 2n=38=20M+10SM+8T for P. neriifolius respectively. The karmorphology of 3 sections in Podocarpus, especially the resting nuclei and basic chromosome number, together with the other data, justified their generic status in the family.

Karyomorphology of Biebersteinia Stephan (Geraniaceae) and its systematic and taxonomic significance

The systematic and taxonomic position of Biebersteinia Stephan has long been in dispute. The present paper describes for the first time the karyomorphology of two species in Biebersreinia Stephan. Both species commonly showed the interphase nuclei of the simple chromocenter type and the mitotic prophase chromosomes of the interstitial type. The karyotype formulae of both B. heterostemon and B. odora were 2n=10=2m(2sec)+8sm(2sec), belonging to the 3A type of Stebbins＇ classification. The karyotype of this genus is recorded for the first time. The basic chromosome numbers of four of the five known species of Biebersteinia have been recorded as x=5. The combination of resting nuclei of the simple chromocenter type, mitotic prophase chromosomes of the interstitial type, two pairs of chromosomes with four obvious secondary constrictions at the mitotic prophase and metaphase stages, and the peculiar 3A karyotype in Biebersteinia can be regarded as the karymorphological marker of this genus. The karyomorphological data presented here do not support the traditional grouping of this genus in Geraniaceae. The unique karyomorphology of Biebersteinia justifies its familiar or ordinal status, which is congruent with embryological, anatomical, chemical and molecular data. The systematic position of Biebersteinia needs further study.

A Cytotaxonomic Study on the Genus Pyrenaria complex (Theaceae)

Eleven species (including 18 samples) of the genus Pyrenaria complex, i.e., Pyrenaria, Tutcheria and Parapyrenaria in the Camellioideae of the family Theaceae, were karyomorphologically in investigated. Features common to all the species investigated include: (1) the simple chromocenter type of the interphase nuclei; (2) the chromosome number of 2n=30 and (3) the small chromosomes with the gradually decreased sizes. The basic chromosome number of x=15 is confirmed for all taxa. AU species investigated are diploid. Only a few unimportant karyomorphological differences were found among these taxa, such as the variation of the number of the median, the submedian and the subterminal centromeric chromosomes, the mean arm ratio, the ratio of the longest chromosome length / shortest chromosome length, and the karyotype asymmetry. These differences show no correlation with the morphological variation and the taxonomic circumscriptions of these taxa. Karyomorphological data provides further evidence for merging Tutcheria and Parapyrenaria into and establishing the genus Pyrenaria in its broad sense (Pyrenaria s.l.). Moreover, karyomorphological data suggest that Pyrenaria s.l. might have a close affinity with and is more primitive than Camellia.

Karyomorphology of some Moraceae and Cecropiaceae (Urticales)

The karyomorphology of 16 species in 13 genera representing Moraceae and Cecropiaceae was investigated in an effort to contribute to a better understanding of chromosome features and evolution in the families. All genera investigated have similar karyomorphology, but differences are found in (1) chromosome features of Interphase nucleus (simple, simple-complex, or complex chromocenter type), (2) basic chromosome number (x=13 or 14), (3) size variation (mono-or bimodial), and (4) frequencies of chromosomes with median centromeres (m-chromosome) (25–85%) and those with subterminal (or terminal) centromeres (st-chromosome) (14–69%). Comparisons with Ulmaceae as an outgroup of the remainder of Urticales suggest that the simple chromocenter type,x=14 comprising bothm- andst-chromosomes, and the monomodial karyotype are plesiomorphies in Moraceae and Cecropiaceae. Most of Moraceae and Cecropiaceae retain generalized chromosome features of the order, but have involved a few evolutionary changes in karyomorphology. Based on some detailed karyomorphological data, inter- and infrafamilial relationships are also briefly discussed.

Comparative karyomorphology and interrelationships ofSelaginella in Japan

Karyomorphological comparisons were made of 16 native and cultivated species ofSelaginella in Japan. The somatic chromosome numbers are 2n=16 inS. boninensis; 2n=18 inS. doederleinii, S. helvetica, S. limbata, S. lutchuensis, S. nipponica, S. selaginoides, S. tama-montana, andS. uncinata; 2n=20 inS. biformis, S. involvens, S. moellendorffii, S. remotifolia, andS. tamariscina; 2n=30 inS. rossii; and 2n=32 inS. heterostachys. The interphase nuclei of all species examined are uniformly assigned to the simple chromocenter type. The metaphase karyotype of 2n=16 (x=8) is 8 m (=median centromeric chromosomes)+8(st+t)(=subterminal and terminal). The group of the species having 2n=18 (x=9) is heterogeneous karyomorphologically: The karyotype ofS. nipponica is 2n=18=6 m+12(st+t),S. tama-montana 10 m+2 sm(=submedian)+6(st+t), andS. uncinata 6 m+7 sm+5(st+t). Although the remaining five species have the common karyotype 8 m+4 sm+6(st+t), the values of mean chromosome length are variable. Another group of the specles having 2n=20 (x=10) is homogeneous, since all species have the same karyotypes 8 m+4 sm+8(st+t) and have similar chromosome size. The karyotype of 2n=30 is 12 m+6 sm+12(st+t) and is suggested to be a triploid of x=10, and 2n=32=16m+16(st+t), a tetraploid of x=8. Thus, three kinds of basic chromosome numbers, x=8, 9, 10 are present in JapaneseSelaginella examined, and their karyomorphological relationships are discussed.

Karyomorphology and relationships of Celtidaceae and Ulmaceae (Urticales)

Based on karyomorphological features, six (examined in this study) of nine genera of Celtidaceae are divided into three groups: 1)Celtis, Parasponia, Pteroceltis andTrema; 2)Aphananthe; 3)Gironniera, and six genera of Ulmaceae into two: 1)Holoptelea andPhyllostylon; 2)Hemiptelea, Planera, Ulmus andZelkova. The first four genera share the simple chromocenter type at the resting stage andx-10, with all chromosomes with submedian or median centromeres (frequency of chromosomes with subterminal or terminal centromeres 0%, although uncertain inTrema).Aphananthe hasx=13, but resembles the above four genera in other features.Gironniera is distinct from all other Celtidaceae in having the diffuse-complex chromocenter type andx=14, features which occur in Ulmaceae. InGironniera the frequency of chromosomes with subterminal or terminal centromeres is 43%, a proportion similar to those inHoloptelea (36%) andPhyllostylon (58%) of Ulmaceae. All six genera of Ulmaceae havex=14, yetHemiptelea, Planera, Ulmus andZelkova are distinct fromHoloptelea andPhyllostylon (with the simple chromocenter type) in having the diffuse-complex chromocenter type and in predominantly possessing chromosomes with subterminal or terminal centromeres (93%). Evidence from karyomorphology, as well as from other sources, suggests 1) thatAphananthe (x=13) is most distantly related to all genera withx=10 within Celtidaceae, 2) thatGironniera may have a key role for understanding evolutionary relationships between Celtidaceae and Ulmaceae, and 3) thatHoloptelea andPhyllostylon represent derivatives of a line that diverged early from a common ancestor or all Ulmaceae. On the basis of comparisons with other Urticales and the putative outgroups of the order, it is also suggested that the chromosome morphology of Ulmaceae represents the more derived state in Urticales.