Relative Chromosome Length Research Articles

Statistical evaluation of length measurements on barley chromosomes with a proposal for a new nomenclature for symbols and positions of cytological markers

In 100 cells of an intergeneric Hordeum×Psathyrostachys hybrid, statistical evaluations were performed on length measurements of barley chromosomes and chromosome arms recognized by their Giemsa C-banding patterns for reliable identification. In 10 cells, we included the results of distance measurements between cytological markers and/or C-bands. Both actual and relative chromosome lengths as well as distances between cytological markers were distributed non-normally. Logarithmically transformed lengths proved to be normally distributed and were used to establish desirable statistical properties of mean values and confidence limits. No barley chromosome could be identified by length alone. Mean values of the logarithmically transformed distances between chromosome ends, constrictions, and Giemsa C-bands were back-transformed and used to construct an idiogram. The generally used nomenclature for chromosome markers and their positions based on C- or N-banding patterns was found arbitrary and inadequate. Instead, we propose a new, more general, informative and simple system for designating chromosome arms and cytological markers. It would be used as follows: (i) one chromosome arm with a specific banding pattern is designated the ‘plus' arm and is depicted upwards in the idiogram; the other arm is designated the ’minus arm; (ii) total genome length is defined as “one GeNome” (symbolized GN); (iii) distances on the idiogram are given in milliGeNomes (mGN), i.e., thousandths of a GN; (iv) the centromere is given the position 0; and (v) cytological markers on the ‘plus' and ’minus' arms are designated by their positive and negative distances in mGN from the 0-position, respectively.

Chromosome Identification and Karyotyping of Satsuma Mandarin by Genomic In Situ Hybridization

Satsuma mandarin (Citrus unshiu Marcow.) chromosomes were stained with Giemsa and fluorochromes chromomycin A3 (CMA)/4′,6-diamidino-2-phenyindole (DAPI). Eighteen chromosomes were categorized into eight groups by the position and relative size of the CMA (+) region and relative length of chromosome. Ponkan (C. reticulata Blanco) DNA labeled with Dig-rhodamine (red) and pummelo [C. maxima (Burm.) Merr.] DNA labeled with biotin-fluorescein isothiocyanate (green) were used as genomic in situ hybridization (GISH) probes. GISH signals were detected on CMA (+) regions and other heterochromatin blocks. The chromosomes were categorized into 12 groups by the coloration and size of GISH signals with relative length of chromosomes. GISH allowed six pairs of speculated homozygous and six individual heterozygous chromosomes of satsuma mandarin to be identified unambiguously. In 10 chromosomes with distinct GISH signals on the CMA (+) regions, red GISH signals were detected on nine chromosomes, indicating that satsuma mandarin is closely related to ponkan. Two colors (red and green) of GISH signals were detected on type C chromosome and three different colors (red, green, and yellow) were detected on type A, indicating that pummelo is involved in the origin of satsuma mandarin. The origins of types A and C chromosomes in satsuma mandarin were also discussed. This article demonstrates that GISH is a powerful tool for chromosome identification and karyotyping in citrus.

Karyotype and C-banding Patterns of Mitotic Chromosomes in Heteranthelium piliferum

The C-banded karyotype of Heteranthelium piliferum species was studied in a natural population from northwest of Iran using aceto-iron-hematoxilin staining and C-banding technique. Chromosome measurements including long arm, short arm and chromosome lengths, arm ratio index, relative chromosome length, heterochromatin percent per chromosome and per chromosome set were made. It was revealed that the karyotype of this species is symmetric and consists of 7 pairs of metacentric chromosomes. Arm ratio index values ranged from 1.01 in chromosome G to 1.44 in chromosome D. One of the chromosomes had a satellite located on the end of its long arm (chromosome G). The Q genome of this species like A, B, D, S, M and M, genomes in diploid species of Aegilops-Trticum group, H genome in Hordeum, E genome in Agropyron and R genome in Secale has metacentric or sub-metacentric chromosomes.

C-banding 패턴에 의한 한국 재래종 찰옥수수 염색체의 Heterochromatic knob 수와 핵형

Giemsa C-banding방법으로 한국 재래종 찰옥수수의 핵형 및 염색체 상에 존재하는 knob의 수와 위치 등을 확인하고 모식도를 통하여 염색체의 특성을 나타내고자 재래종 찰옥수수 5개의 자식 계통 (inbred stock)을 조사하였다. knob의 수는 6-12개이었고 평균 9.2개이었으며 계통별로 차이가 있었으며, knob을 가지고 있는 염색체도계통별로 차이가 있었다. YS-1의 경우 6번, 7번, 8번 그리고 9번 염색체에서 knob을 가지고 있었는데, MY-1의경우 1번, 2번, 3번, 6번, 「번 그리고 9번 염색체에서 knob을 가지고 있었다. 염색체의 장완과 단완의 비율, 염색체의 상대적 길이 등을 비교해 보기 위하여 YS-1과 MY-1 두 계통을 조사해 본 결과 두 계통 간에 차이가 있었고, 염색체의 상대적 길이는 YS-1이 큰 것으로 나타났다. Giemsa C-banding법은 재래종 찰옥수수의 계통별 특성과 이를 이용한 계통 분류에도 효과적으로 이용할 수 있을 것으로 생각된다. A Giemsa C-banding method was used for the identification of somatic chromosomes and heterochromatic knob position in Korean indigenous waxy com (Zea mays L.). 5 inbred stocks were examined and their heterochromatic knob numbers ranged from 6 to 12. In comparison of homologous chromosomes of two stocks of YS-1 and MY-1, knob numbers, knob positions, arm ratios and relative length of chromosomes were different between the genotypes. The length of homologous chromosomes in YS-1 were generally larger than those of MY-1. The Giemsa method was proved to be useful for the identification of somatic chromosome and a C-banded diagram showing knob positions, arm ratios and relative length of chromosome could be used as a good tool to compare the characteristics of chromosomes of Korean indigenous waxy corn stocks.

Comparative Study of Chromosome Morphology and C-banding Patterns in Several Genotypes of Lens culinaris

Karyotype and C-banding patterns of mitotic chromosomes in 10 cultivars and landraces of lentil were studied. Aceto-iron-hematoxilin staining and Giemsa C-banding techniques were used to staining choromosomes and banding patterns analysis, respectively. Chromosome characteristics including long arm, short arm and chromosome lengths, total length of chromosome set, arm ratio index, relative chromosome length, the width and position of each band, heterochromatin percent per chromosome and per chromosome set were measured using Micromeasure software. The results of this study revealed that the genome of this species consisted of four pairs of metacentric and three pairs of submetacentric chromosomes. Chromosome 4 had a secondary constriction near centromeric region of its long arm. Arm ratio index of chromosomes ranged from 1.24 in chromosome 3 to 2.38 in chromosomes 6. Each chromosome, having a distinctive banding pattern, was recognizable. Karyological characteristics and banding patterns of all materials studied were similar to each other, however, some polymorph C-bands were observed on chromosome arms.

Karyological features of the genus Planorbarius (Gastropoda, Pulmonata, Bulinidae) of the Ukrainian fauna

The absence of significant distinctions between the species of the genus Planorbarius in the narrow sense (P. corneus, P. banaticus, P. purpura and P. grandis) has been established. All investigated species had identical chromosomal formulas (2n = 30m + 6sm = 36) and fundamental numbers (FN=72). Reliable distinctions between them were not found by total complement length (TCL), relative length of chromosomes (RL) and centromeric indexes. The species selected on the basis of genetic marking differed clearly by centromeric index of chromosome 12 that confirms the allospecies frame of P. corneus s. lato.

Differential Fluorescent Chromosome Banding of Solanum nigrum L. and Solanum villosum L. from Bangladesh

Two species of the genus Solanum viz. S. nigrum and S. villosum found in Bangladesh were cytogenetically investigated to confirm their taxonomic status. S. nigrum and S. villosum were found to possess 2n=24 and 2n=48 chromosomes, respectively. The centromeric formula 22m+2sm was found in S. nigrum and 48m in S. villosum. No gradual decrease of chromosomal length was observed in both the species indicated their karyotypes as primitive type. The individual chromosomal length ranged from 1.66 to 2.34 μm in S. nigrum and 1.66 to 2.66 μm in S. villosum. The total chromatin length in S. villosum (97.8 μm) was almost double to that of S. nigrum (48.94 μm). The range of relative length of chromosomes was similar in these two species. Solanum nigrum and S. villosum possessed 18 and 17 CMA positive bands, respectively. Most of the CMA-bands were present at the terminal region in both the species. The percentage of CMA banded region in S. villosum (35.43) was almost double to that of S. nigrum (18.69). A pair of DAPI positive bands was found on both the end of all the chromosomes in these 2 species. Each band was 0.5 μm in length. The karyotype of S. nigrum studied here indicated that the specimen was not actually S. nigrum rather it has much simillarities with S. americanum. Solanum villosum showed regular bivalent formation at metaphase-I and segregation at anaphase-I. The overall karyotypic features suggested S. villosum as an ancient auto-tetraploid of S. americanum which in course of time has started regular meiosis.

Cytogenetic characterization of alpaca (Lama pacos, fam. Camelidae) prometaphase chromosomes

The present study provides specific cytogenetic information on prometaphase chromosomes of the alpaca (Lama pacos, fam. Camelidae, 2n = 74) that forms a basis for future work on karyotype standardization and gene mapping of the species, as well as for comparative studies and future genetic improvement programs within the family Camelidae. Based on the centromeric index (CI) measurements, alpaca chromosomes have been classified into four groups: group A, subtelocentrics, from pair 1 to 10; group B, telocentrics, from pair 11 to 20; group C, submetacentrics, from pair 21 to 29; group D, metacentrics, from pair 30 to 36 plus sex chromosomes. For each chromosome pair, the following data are provided: relative chromosome length, centromeric index, conventional Giemsa staining, sequential QFQ/C-banding, GTG- and RBG-banding patterns with corresponding ideograms, RBA-banding and sequential RBA/silver staining for NOR localization. The overall number of RBG-bands revealed was 391. Nucleolus organizer-bearing chromosomes were identified as pairs 6, 28, 31, 32, 33 and 34. Comparative ZOO-FISH analysis with camel (Camelus dromedarius) X and Y painting probes was also carried out to validate X-Y chromosome identification of alpaca and to confirm close homologies between the sex chromosomes of these two species.

A chromosomal investigation of some British Cantharidae (Coleoptera)

The karyotypes of 20 species of Cantharidae occurring in the British Isles are described and illustrated, 19 of which are hitherto unrecorded. These are Cantharis cryptica Ashe, Cantharis fusca Linnaeus, Cantharis lateralis Linnaeus, Cantharis livida Linnaeus, Cantharis nigra (Degeer), Cantharis nigricans (O. F. Müller), Cantharis pallida Goeze, Cantharis pellucida Fabricius, Cantharis rufa Linnaeus, Cantharis rustica Fallén, Cantharis thoracica (Olivier), Rhagonycha fulva (Scopoli), Rhagonycha lignosa (O. F. Müller), Rhagonycha limbata Thomson, Rhagonycha lutea (O. F. Müller), Rhagonycha testacea (Linnaeus), Silis ruficollis (Fabricius), Malthinus seriepunctatus Kiesenwetter, Malthodes dispar (Germar) and Malthodes minimus (Linnaeus). The main findings were as follows: (1) Cantharis, Rhagonycha and Silis have karyotypes of six pairs of autosomes plus sex chromosomes, which are X0 (male), XX (female). (2) Malthinus and Malthodes differ from the other genera in having only five pairs of autosomes. (3) The chromosome complement of Silis differs from those of the other genera studied in having a variable number of B-chromosomes in individuals from the same population. (4) The karyotypes of the Rhagonycha species show a degree of uniformity in the relative chromosome lengths, centromere positions and C-banding patterns. (5) The karyotypes of the Cantharis species are much more distinct from each other where these characteristics are concerned. (6) Maturation of the gonads takes place in the late larval stage. (7) The segregation of the X chromosome of Cantharis rufa during meiosis is pre-reductional.

Karyological analysis of endangered Caspian salmon, Salmo trutta caspius (Kessler, 1877)

The karyotype and chromosomal characteristics of endangered Caspian salmon, Salmo trutta caspius, in the southern part of the Caspian Sea were investigated. From the total of 60 mitotic metaphases achieved from 15 individuals, 15, 9 and 36 metaphases were with the mode <76, 76 and 80 representing 25%, 15% and 60% of metaphases respectively. So, the most common pattern of chromosome number was 80 (36 metaphases, 60%) and the number of diploid chromosomes was thus confirmed as (2n=80) of this subspecies. The karyotype consists of seven metacentric, five submetacentric and 28 telocentric pairs. The karyological parameters of the Caspian salmon, the centromic index, arm ratio, relative length and length variation range of chromosomes, were 0–0.5, 1–∞, 0.011–0.045 and 0.507–2.028 μm respectively. The total length of chromosomes in haploid series was 44.776 μm and fundamental number of chromosome arms was 104. This study may provide the first knowledge on chromosome analysis in Caspian salmon and add basic information useful for its chromosomal manipulations.

A re-evaluation of the Helophorus leontis complex (Coleoptera: Helophoridae) based on chromosomal analysis, with description of H. biltoni sp. nov. from Iran

The Helophorus leontis complex is reviewed in the light of karyotype analysis. One new species, H. biltoni sp. nov., is described from Iran, and H. dixoni Angus is regarded as a distinct species, not a subspecies of H. leontis Angus. The karyotypes of the three species are figured, and show the chromosomes of the three species to have a different sequence or relative chromosome lengths along the karyotype. Meiotic first metaphases of H. biltoni and H. leontis are figured, and show that these species have differently sized sex chromosome bivalents. These data indicate translocational differences between the karyotypes of the three species, which would render hybrids infertile. The aedeagophores of the three species are figured and shown to be morphologically identical. Figures of the heads and pronota are given and show H. biltoni to have a distinctively inflated pronotum. The distributions of the three species and the problem of different species with morphologically identical aedeagophores are discussed.

Studies on the action of mitomycin C and bleomycin on telomere lengths of human lymphocyte chromosomes

In order to address the problem of the action of cytostatics on chromosome ends, telomere length was measured in human lymphocyte cultures exposed to mitomycin C (MMC) and bleomycin (BLM). Telomere-specific PNA probes were used for the quantitative estimation of the relative telomere length of each individual chromosome by fluorescence in situ hybridization. A high inter-cellular and inter-individual variability of relative telomere lengths was found throughout all experiments. Different responses could be observed with respect to the action of the examined mutagens: The total average fluorescence intensity of labeled telomere repeats was decreased under the action of MMC in two of the experiments, while two revealed no significant alteration. BLM caused no significant change of total average telomeric signal intensity in four, a clear decrease in one of the six experiments, and an increase in another. Although all chromosome ends contributed to the observed trends, single telomeres were affected in a very distinct way. The highest concentration of MMC (1 microg/ml) induced significant shortening of telomeres of the chromosome arms; 2q, 3p, 5q, 7p, 10q, 11p, 13q, 17p, 18p&q, and 21q in two independent experiments. In one BLM experiment with 8 microg/ml, the most distinct decrease (p< or =0.005) of telomeric fluorescence was found at the ends of chromosome arms; 1q, 6p, 17p, 20p&q, and 22q. The increase of telomeric signal intensity affected the telomeres of some individual chromosome arms more than others, e.g. 4q, 6p, 7p, 8p, 13p, and 18q. Although the telomere length of the individual chromosome arms varied widely, clear trends could be observed with respect to the rank which was occupied by telomeric length of the various chromosome arms. The telomeres of the 1p, 3p, 4q, 5p, 12q, and 13q chromosome arms throughout all experiments were among the longest; and those of 13p, 15p, 21p, and 22p were among the shortest telomeres of the karyotype. From these data, it can be concluded that MMC affects the telomeric repeat area of chromosomes more than BLM, which mostly had no significant effect on telomere length in the performed experiments.

Chromosome identification and nomenclature of Sorghum bicolor.

Linkage group identities and homologies were determined for metaphase chromosomes of Sorghum bicolor (2n = 20) by FISH of landed BACs. Relative lengths of chromosomes in FISH-karyotyped metaphase spreads of the elite inbred BTx623 were used to estimate the molecular size of each chromosome and to establish a size-based nomenclature for sorghum chromosomes (SBI-01-SBI-10) and linkage groups (LG-01 to LG-10). Lengths of arms were determined to orient linkage groups relative to a standard karyotypic layout (short arms at top). The size-based nomenclature for BTx623 represents a reasonable choice as the standard for a unified chromosome nomenclature for use by the sorghum research community.

Sister chromatid exchange in the goat (Capra hircus).

Lymphocyte cells from 30 Maltese and Syrian derivative goats (13 males and 17 females) reared in southern Italy underwent sister chromatid exchange (SCE) test. For the 902 cells we studied, the SCE-mean values were 6.6 +/- 3.0 per cell for both breeds. The SCE-frequency did not follow a Poisson distribution. The simultaneous visualization of SCEs and G-bands in the lightly stained chromatid allowed the study of SCE-distribution in chromosomes 1 and X. The number of SCEs in chromosome 1 was significantly higher (P > 0.001) than expected from relative chromosome length. No statistical differences between the numbers of SCEs in the active (early-replicating) and inactive (late-replicating) X-chromosomes of female cells were found.

COMPARATIVE KARYOLOGICAL ANALYSIS OF FIVE SPECIES OF VIVIPARUS (GASTROPODA: PROSOBRANCHIA)

Karyological analysis was performed on Viviparus ater (Cristofori & Jan, 1832), V. acerosus Bourguignat, 1862, V. mamillatus (Kuster), V. viviparus (Linnaeus, 1758) and V. contectus (Millet, 1813), collected from different freshwater bodies of Switzerland, Hungary, Albania, Italy and Lithuania. The karyotypes of V. acerosus and V. mamillatus are described for the first time. The diploid number of chromosomes in V. contectus equals 14, whereas in diploid sets of other studied species, 18 chromosomes are present. The karyotype formula is in V. contectus (5m + 2sm, NF = 28, in V. ater, 7m + 1sm-m + 1 sm, in V. acerosus and V. viviparus, 8m + 1sm, NF = 36, in V. mamillatus, 6m + 1m-sm + 1sm-m + 1sm, NF = 36. In females of V. ater, V. mamillatus and V. acerosus, the heteromorphism of chromosome pair no. 8 was observed, with a sex-determining mechanism — ZW female /ZZ male. Although, Z and W chromosomes are metacentric, significant differences (P > 0.05, or P > 0.001) in their size were determined. The interspecific significant differences (P > 0.05) in karyotypes of V. ater, V. mamillatus, V. acerosus and V. viviparus were detected by using one-way ANOVA and Bonferroni¹s Multiple Comparison tests. Only chromosomes of the pair no. 5 were of similar shape in all of these species. The smallest interspecific difference was between V. viviparus and V. acerosus. The intraspecific karyological differences in relative chromosome length and centromeric index of V. contectus from lakes Garda (Italy), Olauka and Asveja (Lithuania) were observed in the chromosome pair no. 5.

KARYOTYPE POLYMORPHISM IN DIFFERENT GEOGRAPHIC POPULATIONS OF GREEN PEACH APHID MYZUS PERSICAE (SULZER) IN CHINA

This paper deals with the karyotype of green peach aphid, Myzus persicae (Sulzer), with three different life cycles in different regions of China. The results showed that four types of karyotype were found in the natural populations of red form and brown form aphids. Four types of karyotype are as follows: 2n = 12 with autosomes 1, 3 translocated (T1–3); 3n = 18 normal triploid; 3n = 18 with T1–3 translocation; and 2n = 11. However, in the yellowish-green aphids there were only two types of karyotype, normal karyotype 2n= 12 (NK) and 2n = 12 with T1–3 translocation. There was no significant difference in the relative lengths of chromosomes in 2n = 12 karyotype among different color forms and groups from different regions.

Karyotype analysis of the genus Clivia by Giemsa and fluorochrome banding and in situ hybridization

The karyotypes of species in the genus Clivia were analyzed by using Giemsa C-banding, fluorochrome staining, silver impregnation and in situ hybridization. Banded ideograms were established with computer aided image analysis. A chromosome number of 2n = 22 and a similar basic karyotype, based on relative chromosome length and arm ratio, was found in all the four species. There were clear differences in banding pattern between the species which allowed their karyotypes, and consequently the species, to be unambiguously identified. Apart from at the centromere, heterochromatin was mainly distributed on the short arms of the smaller chromosomes. Amounts of heterochromatin in C. miniata and C. gardenii were greater than in the other two species. The number of pairs of rDNA sites, identified by in situ hybridization, ranged from one to three.

Non-proportional involvement of Chinese hamster chromosomes 3, 4, 8 and 9 in X-ray-induced chromosomal aberrations

Purpose: To study by fluorescence in situ hybridization (FISH) the involvement of Chinese hamster chromosomes 3, 4, 8, and 9, and their separate chromosome arms in X-ray-induced aberrations. Materials and methods: Male embryonic primary cells of Chinese hamster were used and metaphases were collected and scored at 20h after confluent cells were exposed to 1 and 4Gy X-rays. The frequencies and types of chromosomal aberrations involving chromosomes 3, 4, 8, and 9 were studied by FISH using armspecific painting probes. Proportional distribution of the induced aberrations was tested on the basis of the relative lengths of chromosomes or chromosome arms studied. Results: A non-proportional distribution of breaks, colour junctions as well as apparently simple dicentrics and translocations among the chromosomes studied was observed in the 4Gy group. In general, chromosome 3 was less involved than expected and chromosome 8 was more involved than expected, and chromosomes 4 and 9 were involved as expected. A non-proportional involvement of arms in breaks, colour junctions and apparently simple dicentrics was also observed. The short arm of chromosome 3 was more involved in breaks and colour junctions than expected. The long arm of chromosome 4 was more involved in dicentrics than expected. Conclusions: Results of this study indicate a non-proportional involvement of Chinese hamster chromosomes 3, 4, 8 and 9 as well as their arms in different types of aberrations following irradiation.

Karyotype of Cuphea lanceolata Ait. and Cuphea viscosissima Jacq.

Cuphea lanceolata Alton and C. viscosissima Jacq. are potential germplasm sources of medium‐chain fatty acids. The fertile hybrid between these two species is being used to develop unproved cultivars as a domestic source of these important oils. A total of 1401 Giemsa C‐banded chromosomes from 145 root‐tip cells of these two species are karyotyped with the assistance of computer imaging techniques. Karyotype was defined by measuring individual chromosomes, computing the relative chromosome length and arm ratios, and identifying specific heterochromatic and euchromatic regions of individual chromosomes. The karyotype of these two species (2n = 12) consists of one pair of satellited chromosomes, two pairs of metacentric chromosomes, and two pairs of submetacentric chromosomes. Chromosome 2 is submetacentric in C. viscosissima but metacentric in C. lanceolata. The differences in relative chromosome length between homologous chromosomes of C. viscosissima and C. lanceolata were not significant. Karyotype asymmetry indices are the numerical expression for the general morphology of plant karyotypes. The intrachromosomal asymmetry index is 0.43 and 0.47 and the interchromosomal asymmetry index is 0.25 and 0.26 for C. lanceolata and C. viscosissima, respectively. The similarity of homologous chromosomes and C‐banding patterns indicate a close phylogenetic relationship between C. viscosissima and C. lanceolata.

Karyotype analysis and optimization of mitotic index in Picea mariana (black spruce) preparations from seedling root tips and embryogenic cultures

The effect of hydroxyurea and colchicine solutions on mitotic index was investigated in embryogenic suspensions and in seedling root tips of Picea mariana. Hydroxyurea treatment and 0.6 per cent colchicine solution significantly increased the quantity of mitotic cells which were mostly in the metaphase stage. The highest mitotic index was observed in cells of embryogenic suspensions. The embryogenic lines were cytologically stable and their utilization for karyotype studies and technique development holds great potential. The arm ratios and relative chromosome length values showed the same trends between embryogenic cultures and seedling root tips and among the five black spruce populations studied. This study shows that the black spruce karyotype is asymmetric and semi-advanced, as in Larix and Abies. Three pairs of chromosomes are of the sm-type with submedian centromeres. One pair is median-submedian (msm), six pairs are m-type having median centromeres and two pairs are metacentric or M-type.