Heterochromatin in mitotic chromosomes of theVirilis species group ofDrosophila

The amount of heterochromatin in the genome of ten members of thevirilis species group was determined as the length of C-band chromosome material relative to the total karyotype length. Thevirilis phylad (Drosophila virilis, D. novamexicana, D. americana americana, andD. americana texana) has significantly greater amounts of heterochromatin in the genome than do members of the montana phylad (D. montana, D. lacicola, D. flavomontana, D. borealis, D. ezoana, D. littoralis). Thus, the significant karyotypic change accompanying diversification of these species has involved reduction in their total constitutive heterochromatin. These changes have apparently involved reductions in the amount of centromeric heterochromatin in the autosomes.     

Karyotype and DNA-content evolution in ten species of Crepis (Asteraceae) distributed in Bulgaria

Ten Crepis species from Bulgaria—five perennials (C. viscidula, C. paludosa, C. coryzaefolia, C. bilhynica, C. schochtii) four annuals (C. pulchra, C. sancta, C. setosa, C. zacintha) and one biennial (C. biennis)—were analysed karyologically using haematoxyh staining, Feulgen cytophotometry (scanning densitometry and video-based image analysis), and DNA flow cytometry with propidium iodide. All taxa but the biennial are diploids with descending basic chromosome numbers, x=6, 5, 4, 3. Significant positive correlations were found between nuclear DNA content and karyotype length and nuclear DNA content and karyotypic asymmetry. Together with the results of previous authors our data suggest that evolutionary advancement could be correlated with more symmetrical karyotypes. Negative significant correlations were established between presumably advanced growth habit (from rhizomatous and tap-rooted perennials towards highly specialized annuals) and chromosome number and karyotype length. Nuclear DNA 1C-values on average were higher in perennials than in annuals, but the ranges were overlapping and the differences not significant. Crepis biennis (2n=c. 40, presumably 10x) had the highest DNA quantity, but calculated at its x-level ranked relatively low in the species sample.     

A simple parameter of dispersion index that serves as an adjunct to karyotype asymmetry

In order to refine the measure of karyotype asymmetry a new chromosomal parameter of dispersion index is proposed that has the potential to decipher even the minor karyotypic variations, thus permitting further evolutionary gradations to the karyotype asymmetry classes of Stebbins. The higher the dispersion index, the more specialized would be the karyotype. The dispersion index takes into account the variance lor gradual change in chromosome size within a complementvis-a-vis variance for the position of centromere in a karyotypic totality. The dispersion index is calculated as the proportionate measure of centromeric gradient to the coefficient of variation for chromosome length; wherin centromeric gradient = length of median short arm — length of median chromosome. Thus, the three most important karyotypic criteriaviz., differences in: absolute chromosome size, position of centromere and relative chromosome size, are all covered in the proposed parameter. The effectiveness of dispersion index has been tested on a plant taxa,Papaver L., where karyomorphological details, nuclear DNA content, and morphotaxonomic parameters have been amply elucidated from an evolutionary stand point. It is hoped that dispersion index would find immense utility in delimiting species interrelationships particularly in the closely related taxa, when applied in conjunction with other systematic parameters.     

Chromosomal evolution within the family Estrildidae (Aves) II. The Lonchurae

Thirteen species of estrildid finches belonging to the Lonchurae were examined cytogenetically by G- and C-banding. The major forms of karyotypic change, both within and between species, were pericentric inversions and changes in the amount of heterochromatin. It appears that the direction of chromosome change in this lineage is towards an entirely telocentric karyotype because inversions converting a biarmed chromosome into a telocentric one only occur when all the macrochromosomes of smaller size are also telocentric. A comparison of hybrid fertility data and karyotypic differences indicates that genic factors affecting gonadal development, and not chromosomal rearrangements, are the primary influence in determining hybrid fertility. The chromosomal data was also used to clarify systematic relationships within the Lonchurae and demonstrate that the genus Lonchura as presently construed is polyphyletic.     

Cytotaxonomy of species of Vernonia, section Lepidaploa, group Axilliflorae (Asteraceae, Vernonieae)

Mitotic chromosomes of eight populations of six species of Vernonia sensu Baker (Asteraceae, Vernonieae, section Lepidaploa , group Axilliflorae ) were studied to assess the validity of maintaining the genus as proposed currently ( sensu Baker) or of splitting it into several smaller genera ( sensu Robinson). The species were collected in areas of 'cerrado' and 'campo rupestre' in southern and central-western Brazil. The chromosome numbers were 2 n  = 20–40 and karyotypic analysis showed a predominance of metacentric chromosomes, with some submetacentrics. B chromosomes were seen in one population of V. geminata . The chromosomes varied in length from 0.9 to 4.6 µm, with a total chromatin length of 29.7–45.0 µm and a symmetry index of 41.2–46.9%. The intrachromosomal asymmetry index varied from 0.13 to 0.29, and the interchromosomal asymmetry index varied from 0.15 to 0.21. The dispersion diagram showed that population 1 of V. geminata had the most asymmetrical karyotype. These results do not provide sufficient evidence for a conclusive cytotaxonomic discussion of Vernonia , mainly because of the impossibility of associating any infrageneric group with specific karyotypic characters, and also because of the small number of species analysed so far.  © 2007 The Linnean Society of London. Botanical Journal of the Linnean Society , 2007, 154 , 99–108.     

角堇与大花三色堇染色体核型分析

以2份角堇与4份大花三色堇自交系为试验材料,采用染色体常规压片方法,观察和分析了它们的细胞染色体数目、相对长度、平均臂比等核型指标,以明确两种植物细胞学特点,为分类以及育种提供理论依据。结果表明:(1)2份角堇自交系染色体数目均为2n=2x=26,染色体基数为x=13,染色体核型公式分别为2n=2x=26=8m+12sm+6st、2n=2x=26=4m+16sm+6st,核型不对称系数为67.20%~70.10%,核型分类均属于3B。(2)4份大花三色堇自交系均为四倍体,其中2份(EYO-1-2-1-4、DSRFY-1-1-2)染色体数目为44,核型公式为2n=4x=44=4m+16sm+6st、2n=4x=44=16m+24sm+4st;2份(G10-1-3-1-4、XXL-YB-1-1-1-1)染色体数目为48,核型公式分别为2n=4x=48=8m+20sm+20st、2n=4x=48=4m+36sm+8st,核型不对称系数为66.74%~71.77%,核型分类属于2B、3B。     

Karyotype evolution in the genus Boronia (Rutaceae)

New chromosome counts are reported for Boronia clavata 2 n  = 14, B. heterophylla 'Near White' 2 n  = 15, B.  'Carousel' 2 n  = 16, B. deanei 2 n  = 22, B. chartacea 2 n  = 32, B. keysii 2 n  = 32, B. pilosa 2 n  = 44, B. anethifolia 2 n  = 36 and B. citriodora 2 n  = 108. Studies in 20 genotypes of 18 species and one interspecific hybrid revealed that they are highly complex in terms of chromosome number, ploidy level, chromosomal length, karyotype constitution and asymmetry. Karyotype analysis indicated that Boronia taxa with high chromosome numbers are primitive and those with lower numbers are derived. The basic chromosome number for this genus is suggested to be x = 18. Analysis of chromosome number, variations of total chromosome length (TCL) and average chromosome length (ACL), Nombre Fondamental (NF) and karyotype asymmetry suggest that dysploid reduction is the major mechanism in Boronia karyotype evolution. Chromosomal rearrangements might also have been involved. Origin, chromosome number changes and spread of Boronia are discussed in relation to the species divergence and the geological and climatic changes of the Australian continent.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 142 , 309–320.     

Leaf-area development in King Edward potato plants inoculated with Verticillium albo-atrum and V. dahliae

Leaf-area development in King Edward potato plants infected with Verticillium albo-atrum and V. dahliae was examined both in plants with a normal growth pattern and in those where maturity had been artificially delayed. Methods are described for producing uniform, single-stemmed, initially disease-free host plants, and for measuring their total and green leaf areas throughout their development. Under both growth conditions the pathogens had no apparent effect upon the initiation of new leaves on the main axis of the plant, but they did influence their subsequent development. During the growing period the pathogens caused stunting, thus preventing the production of the potential maximum leaf area, while at maturity the chlorosis and necrosis of the diseased leaves and their premature fall reduced functional leaf area. In diseased plants in which maturity had been delayed, stunting at the apices was more apparent: internode length, leaf petiolar axis length and leaf area were all smaller than in healthy plants, the greatest reductions being shown in leaf area. Cells in the stunted leaves were fewer and smaller than those in healthy leaves. A direct result of leaf-area reduction was the development of smaller tubers, with consequent reduction in the fresh weight, and some reduction in tuber number. V. albo-atrum invariably proved to be more virulently pathogenic than V. dahliae; the use of an average Verticillium index was shown to be a reliable method for estimating relative virulence since it reflected both leaf area and yield reductions. Delaying host maturity and thus lengthening the period of extension growth conferred some resistance on plants infected with V. dahliae; symptom progression was stopped after its initial expression, and consequently leaf area was increased. This form of resistance was not shown in the plants inoculated with V. albo-atrum.     

Effect of laminin on numerical karyotype variability of kangaroo rat kidney cell lines

The numerical karyotypic variability has been investigated in "markerless" epithelial-like Rat kangaroo kidney cell lines NBL-3-11 and NBL-3-17 on cultivation on a laminin-2/4 coated surface. In cell line NBL-3-17, cultivated on the laminin-coated surface for 2, 4 and 12 days, the character of numerical karyotypic variability has changed. In 2 days the general character of cell distribution for the chromosome number did not change, but the frequency of cells with modal number of chromosomes decreases significantly, while that of cells with lower chromosome number show a tendency to increase. At a prolongation of cultivation time to 4 and 12 days, the numerical karyotypic heterogeneity in cell population increases due to a significant change in the general character of cell distribution for the chromosome number, which is caused by a significant decrease in the frequency of cells with the modal number of chromosomes, and by an increase in the frequency of cells with lower chromosome number. The analysis of distribution of individual chromosomes showed that the number of types of additional structural variants of the karyotype (SVK) increases significantly on cultivation on laminin for 2-12 days. In cell line NBL-3-11, cultivated on the laminin-coated surface for 2 and 4 days, the character of numerical karyotypic variability did not change compared to control variants. Possible reasons of the observed changes of numerical karyotypic variability in cell line NBL-3-17 is discussed. The reason of differences in the character of numerical karyotypic variability between cell lines NBL-3-11 and NBL-3-17 possibly consists in the change of gene expression, namely in a dose of certain functioning genes. The polymerase chain reaction with arbitrary primers revealed no differences between DNA patterns of cell lines NBL-3-17 and NBL-3-11. This can reflect a similarity in the primary DNA structure of both cell lines. Hence, these lines differ only in the number of homologous chromosomes (hypotriploid and hypodiploid).     

Karyology of some Brazilian species of Alismataceae

The family Alismataceae ( sensu Cronquist) comprises 11 genera and 75 species of aquatic and semiaquatic herbs. In Brazil, only the two most speciose genera, Echinodorus Rich. ex Engelm. and Sagittaria L., are present. The chromosome number 2 n  = 22 is common to all species. We present karyotypes for eight species, together with their asymmetry index (TF%) and total chromatin length (TCL). All karyotypes have high karyotypic asymmetry and TCL, due to their large and mostly acrocentric chromosomes. The chromosomal evolution of the Alismatidae group is discussed.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 143 , 159−164.     

Cytogenetic characterization of <Emphasis Type="Italic">Amaranthus caudatus</Emphasis> L. and <Emphasis Type="Italic">Amaranthus hybridus</Emphasis> subsp<Emphasis Type="Italic">. cruentus</Emphasis> (L.) Thell.

The present study is aimed to identify genetic variability between two species of Amaranthus viz., A. caudatus and A. hybridus subsp. cruentus, two economically important species, cultivated mainly for grain production. Karyomorphological studies in Amaranthus are scarce, probably due to higher number of small sized chromosomes. Karyomorphological studies were conducted using mitotic squash preparation of young healthy root tips. Karyological parameters and karyotypic formula were established using various software programs and tabulated the karyomorphometric and asymmetry indices viz., Disparity index, Variation coefficient, Total forma percentage, Karyotype asymmetry index, Syi index, Rec index, Interchromosomal and Intrachromosomal asymmetry index and Degree of asymmetry of karyotypes. The mitotic chromosome number observed for A. caudatus was 2n = 32 with a gametic number n = 16 and A. hybridus subsp. cruentus was 2n = 34 with a gametic number n = 17. In A. caudatus the chromosome length during somatic metaphase ranged from 0.8698 to 1.7722 μm with a total length of 39.1412 μm. In A. hybridus subsp. cruentus the length of chromosome ranged from 0.7756 to 1.9421 μm with a total length of 44.9922 μm. Various karyomorphometry and asymmetry indices analyzed revealed the extend of interspecific variation and their evolutionary status.     

A karyological study of some Dianthus L. species (Caryophyllaceae) in Northeast of Iran

This study focuses on karyological investigation of four taxa of Dianthus (Caryophyllaceae) including D. crossopetalus, D. orientalis subsp. stenocalyx, D. orientalis subsp. gorganicus, and Dianthus sp. distributed in Northeast of Iran. The karyotype asymmetry/symmetry was evaluated using two methods: 1) CVCL (coefficient of variation of chromosome length) and CVCI (heterogeneity of the centromeric index); and 2) MCA (mean centromeric asymmetry). The karyotype asymmetry was also used to investigate the relationships among the taxa. Results obtained from the current study revealed that there are two different ploidy levels (2n = 2x = 30 and 2n = 4x = 60) among the investigated taxa. The indices CVCL and MCA described karyotype asymmetry correctly based on variation in chromosome length. Diagram of CVCL vs. MCA seems to be appropriate for karyological delimitation and taxonomic relationships among the Dianthus taxa under study. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Karyotypes of parasitic Hymenoptera: Diversity, evolution and taxonomic significance

Haploid chromosome numbers (n) of parasitic Hymenoptera (= traditional Parasitica + Chrysidoidea) vary from 2 to 23. However, this range can be subdivided into three intervals with n= 14–23 (less derived parasitic wasps, e.g., some Ichneumonidae and Braconidae as well as Gasteruptiidae), 8–13 (many other parasitic Hymenoptera) and 2–7 (Dryinidae, the majority of Chalcidoidea and some advanced Braconidae, e.g. Aphidiinae). The symmetric karyotype with a relatively high chromosome number (n= 14–17) and the prevalence of biarmed chromosomes must be considered as a groundplan feature of parasitic Hymenoptera. Independent reductions of chromosome numbers (n≤ 10–11) occurred in some groups of the superfamily Ichneumonoidea as well as in the common ancestor of the Proctotrupoidea sensu lato, Ceraphronoidea, Cynipoidea and Chalcidoidea. Further multiple decreases in chromosome numbers (n≤ 4–6) took place in some Braconidae, various lineages of the superfamily Chalcidoidea as well as in the family Dryinidae. Two main trends prevailed in the karyotype evolution of parasitic wasps: the reduction of chromosome numbers (mainly due to tandem fusions and less frequently due to centric ones) and karyotypic dissymmetrization (through an increase in size differentiation of chromosomes and/or in the share of acrocentrics in a chromosome set). Although karyotypic features of parasitic Hymenoptera can be used for solving taxonomic problems at various levels, this method is the most effective at the species level.     

Data reassessment in a phylogenetic context gives insight into chromosome evolution in the giant genus Solanum (Solanaceae)

Chromosome data are fundamental in evolution. However, there has been no attempt to synthesize and evaluate the significance of such information from a phylogenetic perspective in the giant genus Solanum, which was the aim of this work. New and published information of the main cytotaxonomic features (chromosome number, polyploidy, total length of the haploid complement, mean chromosome length, mean arm ratio, karyotype formula, nuclear DNA amount, number/position of rDNA sites) was compiled and mapped onto an embracing Solanaceae phylogeny, performing Ancestral States Reconstruction. There were 506 Solanum species with chromosome counts (49.7% from an estimated total of 1,018 spp.), with x?=?12 being the most frequent number (97%). Species with karyotypes represent 18.8%, while 8% have been studied with any molecular cytogenetic technique. Chromosome characters showed transitions associated with supported nodes, some of which have undergone fewer transitions than others. The common ancestor of all Solanum was a diploid with 2n?=?24, a karyotype with st and/or t chromosomes, 2C DNA content of 1–1.2 pg, one locus of 18–5.8–26S rDNA and one of 5S, both loci being asyntenic. The chromosomal variables behave as homoplastic, with reversions in all branches. The analysed characters were sorted from more to less conserved: asynteny of rDNA loci; number of sites of 18–5.8–26S; chromosome number; karyotype formula; number of 5S loci. This pattern of chromosomal evolution distinguishes Solanum from closely related genera and from genera from other families with a similar number of species.     

Chromosome numbers and karyotypes of Catasetum species (Orchidaceae)

Mitotic chromosomes of 12 species of Catasetum were assessed to contribute with the karyotypic study of the subtribe Catasetinae (Orchidaceae), expanding the knowledge of this group in terms of chromosomes and supporting its taxonomic and evolutionary analysis. The species are maintained in cultivation in the greenhouse of the Department of Plant Biology/IB/UNICAMP and in the “Orquidário Frederico Carlos Hoehne” of the Botanical Garden of São Paulo. Chromosome counts ranged from 2n = 54 to 2n = 108. Karyotypes were prepared for all species studied, in which there was a predominance of metacentric chromosomes and some submetacentric ones. The chromosome size ranged from 0.5 to 4.9 μm, the total chromosome length ranged from 34.7 to 78.7 μm and the asymmetry index TF% ranged from 21.2 to 42.3. The results obtained so far favor the taxonomy of the genus, allowing to distinguish species with very similar external morphology.     

Chromosome diversity and evolution in Allium (Allioideae,Amaryllidaceae)

Despite extensive literature on the diversity of karyotypes in Allium is available, no attempt to analyse these data together, within a robust phylogenetic framework, has been carried out so far. Thus, we examined patterns and trends in chromosome evolution across the genus. Based on literature survey, karyo-morphometric features for 207 species belonging to 12 subgenera of Allium were obtained. Included in the data-set were basic chromosome number (x), somatic chromosome number (2n), total haploid (monoploid) chromosome length (THL) and three different measures defining karyotype structure: CV_CI, measuring how heterogeneous are centromeres positions in a karyotype, CV_CL and M_CA, quantifying interchromosomal and intrachromosomal karyotype asymmetry, respectively. Trends in karyotype evolution were analysed by phylogenetic regressions and independent contrasts. Mean karyotypes highlighted differences and similarities in karyotype structure between the 12 subgenera. Further differences were noted when the two parameters for analysing karyotype asymmetry were assessed. In addition, by examining the effects of increasing karyotype dimensions (a proxy for genome size) on karyotype structure and asymmetry, it was shown that in Allium species, the DNA was added proportionally to their arm lengths. Overall, p = 8 and somehow intermediate karyotype asymmetry levels seem to represent plesiomorphic character-states in Allium.     

Effect of laminin on karyotypic variability in cell line of Indian muntjac skin fibroblasts

The numerical and structural karyotypic variability has been investigated in the Indian muntjac skin fibroblasts cell line M and karyotypic variant of this line M' on cultivation on a laminin 2/4 coated surface. In cell line M, cultivated on the laminin-coated surface for 4 and 14 days, and in karyotypic variant M', cultivated for 2, 4 and 14 days, the character of cell distribution for the chromosome number has changed. These changes involve a significant decrease in frequency of cells with model numbers of chromosomes, and an increase in frequency of cells with lower chromosome numbers. As a result, new modal chromosome numbers form. The frequency of cells with 4 chromosomes increases significantly; as a rule, such cells are absent in the control cell variants. Many new additional structural variants of the karyotype (SVK) appear. Detachment of cells M' from the laminin-coated surface followed by a 2 day cultivation on a hydrophilic surface, commonly used for routine cell cultivation, does not restore the control cell distribution for chromosomal number. The frequency of chromosomal aberrations on cultivation of the laminin-coated surface does not change relatively to controls. The observed alterations seem to be due to both disturbances of mitotic apparatus and selection of SVK, which are more advantageous to changed culture conditions of the cell population.     

Cytology and systematics in JapaneseArisaema (Araceae)

Chromosome numbers are determined from 37 populations attributed to 22 taxa of JapaneseArisaema. Of them, chromosome numbers ofA. limbatum var.conspicuum (2n=26),A. minus (2n=26),A. nambae (2n=28) andA. seppikoense (2n=26) are determined for the first time. New chromosome numbers, 2n=26, are reported forA. aequinoctiale, A. limbatum, A. stenophyllum, A. undulatifolium andA. yoshinagae. Three modes of basic chromosome numbers,x=14,x=13 andx=12, occur in JapaneseArisaema. Precise karyotypic comparisons of 20 taxa reveal that taxa withx=14 andx=13 share 26 major chromosome arms and have an obvious chromosomal relationship. One of two submeta-centric chromosomes inx=13 corresponds to two telo-centric chromosomes inx=14. InA. ternatipartitum with 2n=6x=72, ten out of 12 basic chromosomes are the most similar in size and arm ratio with larger ten chromosomes ofA. ringens among JapaneseArisaema examined. A basic chromosome number ofx=14 is the commonest in the genusArisaema and the remaining basic chromosome numbers,x=13 andx=12, seem to be derived through dysploidal reduction by translocating large segments of major arm of telo-centric chromosome onto other minor arm of telo-centric followed by loss of the remainings including a centromere, and by loss of two telo-centrics fromx=14, respectively. Some systematic problems of JapaneseArisaema are discussed based on new cytological data.Arisaema hatizyoense, A. minus andA. nambae are accepted as independent species.     

Redescription of the karyotype of five species of the family Bufonidae (Amphibia: Anura) from central area of Argentina

In this study karyotypic features of the five species of the family Bufonidae from the central area of Argentina are described. The species are Rhinella achalensis, Rhinella arenarum, Rhinella fernandezae, Rhinella schneideri and Melanophryniscus stelzneri. The metaphases were obtained from intestinal and testis cells, using conventional techniques. Twenty metaphasic figures per individual were analyzed and the total length of each chromosome and the length of the four arms were measured. The obtained measurements were processed using Excel 2000 to obtain the average length of the arms p and q, the arm ratio, the centromeric index, the relative chromosome length and the relative arm length. All species showed karyotype 2n = 22, and karyotype formula of 6: 5. Pairs one to six were large, with a relative chromosome length between 18.64–7.59%; pairs seven to eleven were small, with a relative chromosome length between 7.18–2.42%. In all species the chromosome morphology was metacentric or submetacentric. Karyotype and ideograms were made for all species, based on morphometric parameters of the chromosome complement. Finally, discriminant analysis was used to separate the five species analyzed, with a highly significant classification rate of 80% and P < 0.0001. These results agree, in general, with those presented by other authors, however, in M. stelzneri detailed karyological studied have not been made so far, thus this work represents a significant contribution to the karyotypic decryption features of this species and the Rhinellla species from central area of Argentina.