Metacentric Chromosomes Research Articles

Comparative morphological and cytogenetic study of five Asparagus (Asparagaceae) species from Algeria including the endemic A. altissimus Munby

Forty wild populations belonging to five Asparagus species including the endemic A. altissimus were sampled in an east-west bioclimatic gradient of North Algeria. More than 250 individuals were taxonomically examined and karyologically investigated. Meiotic behavior was analyzed for each species. New chromosome numbers were consistent with the base number x = 10 for the genus Asparagus, and two cytotypes, diploid and hexaploid, were observed. Four species were found to have 2n = 20 chromosomes, highlighting the prominence of diploidy in North Africa. One polyploid with 2n = 60 is reported here as the first karyological information on the endemic A. altissimus. Karyotype parameters were established and compared for diploid species. New data provided for A. acutifolius and A. albus indicate differences in the number of submetacentric chromosomes and genome size estimated by total chromosome length. A. acutifolius is distinguished by the largest genome, the smallest being that of A. horridus. The hexaploid cytotype consists of very small metacentric chromosomes. All diploid species displayed regular meiotic behavior with mostly bivalent pairing. Abnormalities, including univalents, multivalents, laggards, and bridges, were sometimes observed in A. horridus and A. officinalis. The new cytogenetic information provided in this study is discussed in the biogeographic context of the North African flora.

Mechanisms of Chromosomal Diversification in Species of Rineloricaria (Actinopterygii: Siluriformes: Loricariidae).

Cytogenetic studies in fish of the Rineloricaria genus have already shown a high variation in diploid number (2n). Along with fusion/fission events for 2n alteration, inversions contribute to the diversification of chromosome formulae within this group. The present study assessed different populations/species of the Rineloricaria aiming to describe the karyotype organization of its members and understand the mechanisms that lead to the variation of chromosome numbers. Cytogenetic data showed distinct karyotype organization among Rineloricaria populations/species studied, ranging in diploid number from 46 to 64 chromosomes, syntopic species and two karyomorphs in Rineloricaria pentamaculata. Using ribosomal DNAs (rDNAs) and TTAGGGn probes by fluorescence in situ hybridization in species with low diploid numbers, we detected sites of 18S rDNA, 5S rDNA, and TTAGGGn in centromeric regions of metacentric chromosomes, which participated in chromosome rearrangements like centric fusions. In species with high 2n, centric fissions probably occurred in karyotypic diversification. In this study, we assessed the telomeric instability, chromosomal breaks, and rearrangements due to interstitial telomeric site vestiges detection, in addition to the probable role of rDNAs in chromosome fusions in karyotypic diversification of this group.

Unraveling the karyotype structure of the spurges Euphorbia hirta Linnaeus, 1753 and E. hyssopifolia Linnaeus, 1753 (Euphorbiaceae) using genome size estimation and heterochromatin differentiation.

Euphorbia Linnaeus, 1753 (Euphorbiaceae) is one of the most diverse and complex genera among the angiosperms, showing a huge diversity in morphologic traits and ecologic patterns. In order to improve the knowledge of the karyotype organization of Euphorbia hirta (2n = 18) and Euphorbia hyssopifolia (2n = 12), cytogenetic studies were performed by means of conventional staining with Giemsa, genome size estimations with flow cytometry, heterochromatin differentiation with chromomycin A3 (CMA) and 4’,6-diamidino-2-phenylindole (DAPI) and Giemsa C-banding, fluorescent in situ hybridization (FISH) with 45S and 5S rDNA probes, and impregnation with silver nitrate (AgNO3). Our results revealed small metacentric chromosomes, CMA+/DAPI0 heterochromatin in the pericentromeric regions of all chromosomes and CMA+/DAPI− in the distal part of chromosome arms carriers of nucleolar organizing regions (NORs). The DNA content measurements revealed small genomes for both species: Euphorbia hirta with 2C = 0.77 pg and Euphorbia hyssopifolia with 2C = 1.41 pg. After FISH procedures, Euphorbia hirta, and Euphorbia hyssopifolia presented three and four pairs of terminal 45S rDNA sites, respectively, colocalizing with CMA+ heterochromatic blocks, besides only one interstitial pair of 5S rDNA signals. Additionally, the maximum number of active NORs agreed with the total number of observed 45S rDNA sites. This work represents the first analysis using FISH in the subfamily Euphorbioideae, revealing a significant number of chromosomal markers, which may be very helpful to understand evolutionary patterns among Euphorbia species.

Detecting Mechanisms of Karyotype Evolution in Heterotaxis (Orchidaceae).

The karyotype is shaped by different chromosome rearrangements during species evolution. However, determining which rearrangements are responsible for karyotype changes is a challenging task and the combination of a robust phylogeny with refined karyotype characterization, GS measurements and bioinformatic modelling is necessary. Here, this approach was applied in Heterotaxis to determine what chromosome rearrangements were responsible for the dysploidy variation. We used two datasets (nrDNA and cpDNA, both under MP and BI) to infer the phylogenetic relationships among Heterotaxis species and the closely related genera Nitidobulbon and Ornithidium. Such phylogenies were used as framework to infer how karyotype evolution occurred using statistical methods. The nrDNA recovered Ornithidium, Nitidobulbon and Heterotaxis as monophyletic under both MP and BI; while cpDNA could not completely separate the three genera under both methods. Based on the GS, we recovered two groups within Heterotaxis: (1) "small GS", corresponding to the Sessilis grade, composed of plants with smaller genomes and smaller morphological structure, and (2) "large GS", corresponding to the Discolor clade, composed of plants with large genomes and robust morphological structures. The robust karyotype modeling, using both nrDNA phylogenies, allowed us to infer that the ancestral Heterotaxis karyotype presented 2n = 40, probably with a proximal 45S rDNA on a metacentric chromosome pair. The chromosome number variation was caused by ascending dysploidy (chromosome fission involving the proximal 45S rDNA site resulting in two acrocentric chromosome pairs holding a terminal 45S rDNA), with subsequent descending dysploidy (fusion) in two species, H. maleolens and H. sessilis. However, besides dysploidy, our analysis detected another important chromosome rearrangement in the Orchidaceae: chromosome inversion, that promoted 5S rDNA site duplication and relocation.

New chromosome counts, polyploidy, and karyotype evolution inAsterL. (Asteraceae: Astereae) from the Qinghai-Tibet Plateau

AbstractAster L. is a highly diversified genus in the Qinghai-Tibet Plateau and its adjacent areas. Chromosome numbers and karyotypes are reported for 26 populations representing 16 species and three varieties of Aster from this region. Chromosome numbers have been newly documented for 10 species. The basic number of x = 9 is confirmed for all species. Of the 16 species counted, seven species are polypoids, of which six are found with different levels of polyploidy. The remaining nine species are diploid, with 2n = 18. A new polyploid cytotype (hexaploid) is found in A. asteroides and A. souliei. B chromosomes are observed in A. oreophilus and A. boweri. Satellite chromosomes are found in A. semiprostratus and A. boweri. Our results indicate that Aster is an active group in chromosome evolution as characterized by a number of species with different levels of polyploids. The karyotypes are symmetrical with a high proportion of metacentric and submetacentric chromosomes, belonging to type 1A or 2A according...

Evidence for Karyotype Polymorphism in the Free-Living Flatworm, Macrostomum lignano, a Model Organism for Evolutionary and Developmental Biology.

Over the past decade, the free-living flatworm Macrostomum lignano has been successfully used in many areas of biology, including embryology, stem cells, sexual selection, bioadhesion and aging. The increased use of this powerful laboratory model, including the establishment of genomic resources and tools, makes it essential to have a detailed description of the chromosome organization of this species, previously suggested to have a karyotype with 2n = 8 and one pair of large and three pairs of small metacentric chromosomes. We performed cytogenetic analyses for chromosomes of one commonly used inbred line of M. lignano (called DV1) and uncovered unexpected chromosome number variation in the form of aneuploidies of the largest chromosomes. These results prompted us to perform karyotypic studies in individual specimens of this and other lines of M. lignano reared under laboratory conditions, as well as in freshly field-collected specimens from different natural populations. Our analyses revealed a high frequency of aneuploids and in some cases other numerical and structural chromosome abnormalities in laboratory-reared lines of M. lignano, and some cases of aneuploidy were also found in freshly field-collected specimens. Moreover, karyological analyses were performed in specimens of three further species: Macrostomum sp. 8 (a close relative of M. lignano), M. spirale and M. hystrix. Macrostomum sp. 8 showed a karyotype that was similar to that of M. lignano, with tetrasomy for its largest chromosome being the most common karyotype, while the other two species showed a simpler karyotype that is more typical of the genus Macrostomum. These findings suggest that M. lignano and Macrostomum sp. 8 can be used as new models for studying processes of partial genome duplication in genome evolution.

Karyological analysis of Korean endemic land snail,Koreanohadra kurodana(Gastropoda: Bradybaenidae)

AbstractThe karyotypes of the Korean endemic land snail, Koreanohadra kurodana, were investigated using the air-drying method. The diploid chromosome number for this species was 2n = 58, including 23 metacentric chromosome pairs, five submetacentric chromosome pairs and one telocentric chromosome pair; therefore, the fundamental number was FN = 56. Observed chromosomes ranged from 2.1 to 8.5% in total length and the mean total length of the chromosomes in the diploid was 95.5 ± 1.34 μm.

Characterization of a very rare case of living ewe-buck hybrid using classical and molecular cytogenetics.

The natural occurrence of live hybrid offsprings between sheep and goats has been documented in literature, however all the studies have reported the mating of goats with rams, whereas the reciprocal cross was never documented. This study reports on a very rare case of interspecies hybridization occurred between a ewe (2n = 54, XX) and a buck (2n = 60, XY). The hybrid, born in a German flock under natural conditions, is characterised by an intermediate karyotype (2n = 57, XX). The CBA-banding has shown 3 metacentric and 54 acrocentric chromosomes, whereas the GTG- and RBA-banding have revealed that the autosomes involved in the hybrid combination were CHI1, 3; CHI2, 8 and CHI5, 11 corresponding to the metacentric chromosomes OAR1, OAR2 and OAR3. A tri-colour FISH using chromosome paintings and BAC probes has validated this arrangement. A further FISH analysis has been carried out to analyse the telomeres, which showed a normal structure. Nucleolus organiser-bearing chromosomes were identified as pairs OAR1p(CHI3), OAR2q(CHI2), OAR3q(CHI5), OAR4(CHI4) and OAR25(CHI28), and nuclear associations were found. Sex chromosomes were correctly arranged. The odd number of the karyotype might be responsible for a reduced fertility as consequence of the incorrect chromosomal pairing and/or segregation during the meiosis.

A NEW SPECIES OF CENTAUREA (ASTERACEAE) FROM TURKEY<br />

A new species of Centaurea (Asteraceae) from Turkey is described and illustrated. Centaurea nallihanense Uysal & Hamzaoğlu occurs on stony slopes of corrupted oak openings in the Province of Ankara in Central Anatolia. It seems to be similar to C. sect. Ptosimopappus but related to the Cheirolepis-Pseudoseridia complex. Diagnostic characters of similar taxa are provided and a comprehensive discussion is held on the basis of molecular and karyological data. The geographical distribution of the new species is mapped. The chromosome number of C. nallihanense, 2n = 2x = 18, counted in root tips, is also reported and illustrated. Its karyotype formula is 6m+3sm. The karyotype of C. nallihanense consists of mainly metacentric chromosomes with the length ranging from 1.113 to 1.771 µm, and the total haploid chromosome length of 12.909 µm. Also, the ITS gene region of the new species is amplified and sequenced to compare with the relatives and to identify the taxonomical position of the new species within Centaurea.

Karyomorphology of Turkish species in Centaurea sections Centaurea and Phalolepis (Asteraceae) and implications for taxonomy

In this paper, 31 mostly endemic and locally distributed Turkish Centaurea taxa belonging to Centaurea and Phalolepis sections were examined in terms of their karyomorphology. The basic chromosome number for all of the studied species was concurringly determined as 9(x = 9) for both sections, excluding C. hierapolitana. We also determined tetraploid and hexaploid species in spite of many species having diploid chromosome numbers. Twelve chromosome counts are reported for the first time and most of the karyotyping analyses are described for the first time via the KAMERAM program. The karyotypes had a predominance of metacentric (m) chromosomes. However, in the karyotyping of six taxa, submetacentric (sm) chromosomes were dominant. Five quantitative asymmetric indices were used to evaluate karyological features of the species. A meaningful dendrogram was carried out to assess the karyotype-symmetry conditions and describe the karyotyping relationships between different taxa.

Insights into the Andean genera Bridgesia and Guindilia (Sapindaceae): an integrated approach

Sapindaceae s.l. is a moderately large family of trees, shrubs and lianas. The genera Bridgesia and Guindilia belong to the Thouinieae tribe; however, its circumscription to this tribe is in doubt. This work presents a comparative analysis of pollen morphology between species of both genera. They share the basic spherical tricolporate pollen type for the family, but the features studied do not characterize any of them. In addition, the work intends to characterize the karyotype and genome size evolution of both genera, and elucidate the phylogenetic relationships within the family through maximum likelihood and Bayesian analyses of the ITS, trnL and trnL-F sequences. Our results show two different patterns regarding karyotype data: Bridgesia presents 2n = 2x = 28, with metacentric and submetacentric chromosomes; the basic number of the genus, x = 14, is in agreement with the 25% of the chromosome numbers recorded in Sapindaceae. The genus Guindilia exhibits a basic number x = 10; of the three species G. cristata and G. trinervis present metacentric, submetacentric and subtelocentric chromosomes, whereas G. dissecta shows only metacentric and subtelocentric ones. In addition, G. cristata is a polyploid species, with DNA content exactly three-fold that of the diploid species, suggesting a recent event of polyploidization in this species. The infra-familial phylogenetic relationship and circumscription of both genera analysed here evidence that Bridgesia belongs to Paullinia group. The fact that Guindilia is grouped in a different clade encouraged us to propose a new informal tribal group, Guindilia group, in the current infrafamilial arrangement of Sapindaceae.

Karyotype variation in 11 species of the Vernonieae Cass. tribe (Asteraceae Bercht. & J. Presl)

The Vernonieae tribe presents strong taxonomic delimitation problems as it is considered one of the most complex groups of the Asteraceae family, comprising approximately 1100 species distributed across 129 genera. In this study, a comparative analysis of the Vernonieae species was performed to understand the events involved in the chromosome evolution of these species and to further deduce their taxonomy. The representatives were cytogenetically characterized via analyses of morphology, karyotype asymmetry and differential staining with fluorochromes CMA and DAPI as well as FISH. According to morphometric data, all species showed symmetrical karyotypes with prevailing metacentric chromosomes, even in species belonging to different genera. Variability in diploid chromosome number was detected (2n = 18 to 2n = 60), and chromosome sizes were observed to be between 1.00 and 4.09 μm. Additionally, variation in the pattern of heterochromatin was observed mainly in relation to CMA+ bands, in which the number varied from 4 to 16 heterochromatic regions. Only one species, Vernonia scorpioides, presented positive DAPI bands, which were located in the terminal position in most of the chromosomes. The differences in the sizes and quantities of heterochromatic bands may be related to small structural rearrangements during karyotype evolution of the Vernonieae tribe.

Characterization of chromosomal rearrangements in pileated gibbon (Hylobates pileatus) using multiplex-FISH technique

Here we aimed to characterize evolutionary conserved chromosomal rearrangements of pileated gibbon (H. pileatus, HPI) compared to human using multiplex fluorescence in situ hybridization (M-FISH) technique. Khon Kaen Zoo, Thailand, kindly provided the blood specimen of this gibbon. Lymphoblast cells were cultured from male HPI by standard method; chromosome preparation was done following standard protocols. All 24 human (Homo sapiens, HSA) chromosome probes (M-FISH probe set) were applied on HPI. Results indicated that male HPI had diploid chromosome numbers of 2n = 44; the karyotype consists of metacentric and submetacentric chromosomes. During evolution chromosomes of HPI underwent certain rearrangements when compared with human chromosomes and showed 55 conserved regions of different sizes. Majority of HPI chromosomes are constituted of regions being homologous to two or more human chromosomes. The remainder appeared to be conserved, such as HPI chromosomes 14, 17, 18, 20, 21, X and Y which were homologous to only one human chromosome, each. To the best of our knowledge, this is the first study using all 24 HSA probes on HPI; the genetic data may be additionally useful for comparison of gibbons, both within and between genera, to elucidate and clarify more regarding evolutionary lineage of animals in the order primates derived from the same common ancestor known so far.

Karyotypic stability in the paleopolyploid genus Ceiba Mill. (Bombacoideae, Malvaceae)

The genus Ceiba Mill. belongs to the subfamily Bombacoideae (Malvaceae), a paleopolyploid lineage characterized by numerous small chromosomes, which has frequently been reported to have variable intra- and interspecific chromosome numbers. The genus is of Miocene origin, representing a suitable model for studying the relationships between chromosome variability and paleopolyploidy. A comparative cytogenetic analysis of five Ceiba species was undertaken to determine their karyotype variability. New chromosome number counts, chromosome morphological observations, CMA/DAPI double staining, and in situ hybridization (FISH) with 5S and 45S rDNA were performed for five Ceiba species, which represent three out of five main lineages of the genus. Karyotypic data were discussed in the light of molecular phylogenies available for the group. All species showed 2n = 86 and similar karyotypes, composed predominantly of metacentric chromosomes. Two pairs of CMA+/DAPI− bands were located on the short arms of the metacentric chromosomes. The CMA+ bands colocated with 45S rDNA sites, while the 5S rDNA sites were situated in the interstitial regions of other chromosome pairs. Contrary to the intra- and interspecific chromosome number diversity reported for Ceiba species in the literature, our findings suggest chromosome number stability in four of the five lineages within the genus for which data are available. Moreover, our data suggest that karyotypes are evolutionary conserved in the three lineages for which we generated new karyotypic data. Our data, as well as recent cytogenetic reviews of other Bombacoideae genera, indicate numerical stability for these taxa suggesting that counting errors, especially in earlier research, may have overestimated karyotype variability. Chromosome count errors can be attributed to technical difficulties associated with high chromosome numbers, and/or the reduced size of Bombacoideae chromosomes.

Chromosome numbers and karyomorphology of Festuca circummediterranea Patzke group (Poaceae, Loliinae)

The first comprehensive karyological overview of the group of Festuca circummediterranea, comprising 10 Euro-Mediterranean taxa (5 species and 7 subspecies, including autonyms), is provided. Thirty populations were sampled from across almost the whole distributional range of the aggregate, including the loci classici of each taxon. The first chromosome counts for F. jeanpertii subsp. jeanpertii, subsp. achaica, and subsp. gracilis are reported. All the taxa were found to be diploid (2n = 14) and have a similar karyotype, characterized by the predominace of metacentric and submetacentric chromosomes; the occurrence of B-chromosomes was recorded from a single taxon, F. marginata subsp. gallica.

Intrinsic Radiosensitivity and Cellular Characterization of 27 Canine Cancer Cell Lines.

Canine cancer cell lines have progressively been developed, but are still underused resources for radiation biology research. Measurement of the cellular intrinsic radiosensitivity is important because understanding the difference may provide a framework for further elucidating profiles for prediction of radiation therapy response. Our studies have focused on characterizing diverse canine cancer cell lines in vitro and understanding parameters that might contribute to intrinsic radiosensitivity. First, intrinsic radiosensitivity of 27 canine cancer cell lines derived from ten tumor types was determined using a clonogenic assay. The 27 cell lines had varying radiosensitivities regardless tumor type (survival fraction at 2 Gy, SF2 = 0.19–0.93). In order to understand parameters that might contribute to intrinsic radiosensitivity, we evaluated the relationships of cellular radiosensitivity with basic cellular characteristics of the cell lines. There was no significant correlation of SF2 with S-phase fraction, doubling time, chromosome number, ploidy, or number of metacentric chromosomes, while there was a statistically significant correlation between SF2 and plating efficiency. Next, we selected the five most radiosensitive cell lines as the radiosensitive group and the five most radioresistant cell lines as the radioresistant group. Then, we evaluated known parameters for cell killing by ionizing radiation, including radiation-induced DNA double strand break (DSB) repair and apoptosis, in the radiosensitive group as compared to the radioresistant group. High levels of residual γ-H2AX foci at the sites of DSBs were present in the four out of the five radiosensitive canine cancer cell lines. Our studies suggested that substantial differences in intrinsic radiosensitivity exist in canine cancer cell lines, and radiation-induced DSB repair was related to radiosensitivity, which is consistent with previous human studies. These data may assist further investigations focusing on the detection of DSB for predicting individual response to radiation therapy for dogs, regardless of tumor type.

Karyotype Ikan Mas (Cyprinus carpio Linnaeus 1758) Majalaya

Common carp (Cyprinus carpio Linnaeus 1758) is grouped into Family Cyprinidae and Order Cypriniformes. One of Indonesian common carp which is commonly domesticated in Indonesia to fulfil consumer needs of animal protein is “Majalaya”. Even though the common carp “Majalaya” is extensively domesticated to meet market demands, any comprehensive study on the fish chromosomes has not been investigated. Chromosome study on the common carp “Majalaya” is quite important related to breeding program including certification process. The objective of this study was to study karyotype of the common carp “Majalaya” collected from UKBAT Cangkringan, Yogyakarta. Chromosome preparation of the common carp “Majalaya” investigated in this study was a splash method with blood cell cultures. The results revealed that the common carp “Majalaya” has diploid chromosome number (2n) = 98 classified as 12 (6 pairs) metacentric chromosomes and 86 (43 pairs) telocentric chromosomes displaying karyotype formula 2n = 2x = 98 = 12 m + 86 t. However, sex chromosomes of the common carp “Majalaya” could not be identified in this study. In addition, the variation of total length chromosomes of the fish is between 1,052 μm and 3,299 μm. On the basis of R value (3,079 ± 0.093), the common carp “Majalaya” has chromosome variation size

Taxonomy and Evolution ofTropidurus(Iguania, Tropiduridae) Based on Chromosomal and DNA Barcoding Analysis

Abstract Tropidurus is a widespread genus of lizards in Brazilian biomes, particularly common in the state of Bahia, northeastern Brazil. However, genetic studies of populations and species of this group are still scarce. We used chromosomal and DNA barcoding analyses to examine 12 populations of five species of Tropidurus from semiarid (caatinga) and Atlantic forest portions of Bahia. All populations shared a karyotype with 2n = 36 divided into 12 metacentric and submetacentric chromosomes and 24 microchromosomes. The microchromosomes were acrocentric in most of species, but metacentric microchromosomes were observed in Tropidurus semitaeniatus, determining variation in fundamental number of arms from 48 to 52. One population of Tropidurus hispidus presented a supernumerary chromosome. Pericentromeric heterochromatin was detected in most microchromosomes and two pairs of macrochromosomes presented interstitial and pericentromeric C-bands. The nucleolar organizer regions (NORs) were single in Tropidurus e...

Integrated gene mapping and synteny studies give insights into the evolution of a sex proto-chromosome in Solea senegalensis

The evolution of genes related to sex and reproduction in fish shows high plasticity and, to date, the sex determination system has only been identified in a few species. Solea senegalensis has 42 chromosomes and an XX/XY chromosome system for sex determination, while related species show the ZZ/ZW system. Next-generation sequencing (NGS), multi-color fluorescence in situ hybridization (mFISH) techniques, and bioinformatics analysis have been carried out, with the objective of revealing new information about sex determination and reproduction in S. senegalensis. To that end, several bacterial artificial chromosome (BAC) clones that contain candidate genes involved in such processes (dmrt1, dmrt2, dmrt3, dmrt4, sox3, sox6, sox8, sox9, lh, cyp19a1a, amh, vasa, aqp3, and nanos3) were analyzed and compared with the same region in other related species. Synteny studies showed that the co-localization of dmrt1-dmrt2-drmt3 in the largest metacentric chromosome of S. senegalensis is coincident with that found in the Z chromosome of Cynoglossus semilaevis, which would potentially make this a sex proto-chromosome. Phylogenetic studies show the close proximity of S. senegalensis to Oryzias latipes, a species with an XX/XY system and a sex master gene. Comparative mapping provides evidence of the preferential association of these candidate genes in particular chromosome pairs. By using the NGS and mFISH techniques, it has been possible to obtain an integrated genetic map, which shows that 15 out of 21 chromosome pairs of S. senegalensis have at least one BAC clone. This result is important for distinguishing those chromosome pairs of S. senegalensis that are similar in shape and size. The mFISH analysis shows the following co-localizations in the same chromosomes: dmrt1-dmrt2-dmrt3, dmrt4-sox9-thrb, aqp3-sox8, cyp19a1a-fshb, igsf9b-sox3, and lysg-sox6.

Karyotype analysis in someCharaspecies (Charales, Charophyceae) in Iran

AbstractKaryological characteristics were determined in 36 populations of eight Chara species and varieties distributed in Iran. The karyotype asymmetry/symmetry were evaluated using CVCL (coefficient of variation of chromosome length), CVCI (heterogeneity of the centromeric index) and MCA (mean centromeric asymmetry). Results obtained from the current study revealed that there are two different ploidy levels (n = 14 and n = 28) among the investigated taxa. All eight species and varieties had metacentric (M & m), sub-metacentric (Sm) and sub-telocentric (St) chromosomes, but the majority of taxa showed a dominance of metacentric and sub-metacentric chromosomes. In general, the karyotypes within the genus Chara were symmetrical, but the studied species differed significantly in quantitative features of karyotype and revealed the occurrence of qualitative changes during the species diversification. The present study reveals that karyological features may be of great help in Chara species delimitations.