Karyotype analysis of Eucinostomus argenteus, E. gula, E. harengulus, and Eugerres plumieri (Teleostei, Gerreidae) from Florida and Puerto Rico

The karyotypes of four gerreids of the western Atlantic Ocean are documented. A diploid chromosome complement of 48 telocentric chromosomes was found in the four species (2N=48t, fundamental number FN=48). No differences were detected either in the number of chromosomes of the standard karyotype, in their karyotype size, or between the karyotypes derived from male or female specimens of any of the species. Chromosome length decreased progressively and slightly from pair 1 to pair 24. The Ag–NOR karyotypes of E. argenteus and E. harengulus were characterized by the position of the nucleolar organizer regions next to the centromere in chromosome pair 1, whereas in E. gula and E. plumieri Ag–NORs were detected in pair 4. The other 46 chromosomes showed a light staining of the centromere with no terminal or intermediate heterochromatic blocks. All Eucinostomus species showed Ag–NORs of similar size, while Eugerres plumieri showed Ag–NORs 10–20% larger than Eucinostomus species. A combination of size and position of the Ag–NORs identified E. gula, while size alone identified E. plumieri. However, the ancestral state for size and position of Ag–NORs could not be established. There was no differential staining of the chromosomes by G-banding. The karyotype of the gerreids appears similar to the hypothetical ancestral karyotype of fish. The phylogenetic relationships among these species could not be established because of the lack of chromosome G-bands. Most likely this indicates a homogeneous distribution of GC nucleotides in the chromosomes.     

Cytogenetic variability in genus odontocheila (Coleoptera,Cicindelidae): karyotypes,C-banding,NORs and localisation of ribosomal genes of O. confusa and O. nodicornis

Two species of Odontocheila, O. confusa and O. nodicornis, from the Neotropical Region were studied regarding their karyotypes, localisation and activity of ribosomal genes and C-banding. The species, although belonging to the same genus, have quite distinct karyotypes. O. confusa has 10 pairs of autosomes and a single sex chromosome mechanism of the XY/XX type, thus a diploid value of 2n = 22 in males and females. One aneuploid male with a diploid number of 2n = 20 and one male with three B chromosomes were found in a total of eight males studied. O. nodicornis has 17 autosomal pairs and also a single chromosome system but of the X0/XX type, thus a diploid value of 2n = 35 in males and 2n = 36 in females. Fluorescence in situ hybridisation (FISH) revealed the presence of rDNA clusters in two autosomes in both species in mitotic and meiotic figures. Silver staining of male interphase nuclei confirmed the FISH results and showed that all rDNA genes were active. C-banding analysis revealed the presence of constitutive heterochromatin in the centromeres of all chromosomes in the two species plus two pairs in O. nodicornis with terminal positive C-bands. These results are discussed from the cytogenetic and evolutionary point of view.     

GIEMSA C-BANDED KARYOTYPES OF SEVEN NORTH AMERICAN SPECIES OF ALLIUM

The karyotypes of seven North American Allium species were studied by Giemsa C-banding technique. Two species (A. shoenoprasum and A. tricoccum) were diploids with 2n = 16 chromosomes. Three species (A. cernuum, A. douglasii and A. geyeri) were also diploids but with 2n = 14 chromsomes. Diploid and tetraploid populations of A. textile (2n = 14, 28) were studied. The population of A. canadense studied here was a tetraploid (2n = 28). All these North American species, except A. geyeri, possessed centromeric bands in all their chromosomes and nucleolar constriction bands in their satellited chromosomes. Allium shoenoprasum contained telomeric bands in most of its chromosomes but the other species had them only in a small number of chromsomes. Only three species (A. shoenoprasum, A. textile and A. tricoccum) were found to have intercalary bands in some chromosomes. The heterochromatin distribution in B chromosomes of three species was also observed. In A. cernuum, the heterochromatin occupied most of the length of all its Bs, but in A. shoenoprasum, heterochromatin was concentrated in the centromeric region. One population of A. textile (CC1179) was found to have a B chromosome in which very little heterochromatin existed.     

Karyotypes of metaphase chromosomes in diploid populations of<Emphasis Type="Italic"> Dendranthema zawadskii</Emphasis> and related species (Asteraceae) from Korea: diversity and evolutionary implications

Although the Dendranthema zawadskii complex has been known to comprise a series of polyploids (4×, 6×, 8×), we found diploid individuals (with 2n=18) to occur in four populations of D. zawadskii var. latilobum in the southern region of Korea. Karyotypes of metaphase chromosomes were diverse because numbers of metacentric, submetacentric, and acrocentric chromosomes differ even within a population. A total of 17 karyotypes were found in 31 diploid individuals collected from the four populations. The karyotypes were also diverse in the presence or absence of chromosomes with a secondary constriction on a short or long arm and, if present, in the number of such chromosomes. They were further diverse in the presence or absence of non-homologous chromosome(s), the presence or absence of a chromosome with a satellite, and, if present, how many and where satellites are present. Almost the same pattern of diversity was found in diploid individuals (with 2n=18) of D. boreale and D. indicum as well, irrespective of whether they occur together with D. zawadskii var. latilobum or not. Structural features of chromosomes in the variously different karyotypes suggest that reciprocal translocation and the hybridization between individuals with different karyotypes had repeatedly occurred not only in D. zawadskii var. latilobum, but also in D. boreale and D. indicum. Morphologically intermediate individuals between D. zawadskii var. latilobum and D. indicum suggests that the hybridization occur with different species as well. Electronic Publication     

Chromosome evolution in the Brachytheciaceae

Abstract

Twenty-eight moss species have been investigated cytologically. Mitotic karyograms have been presented for most of these species and these show a remarkable similarity in the n = 11 karyotype. Nine of the eleven chromosomes have terminal or sub-terminal centromeres. Lightly staining heterochromatic bands frequently occur along the axis of the chromosomes and very often these are the sites of chromosome bending; it has been suggested that these may be areas of neocentric activity. The karyotypes investigated show a reduction series of chromosome number which is paralleled by an increase in the number of long metacentrics; since the number of major chromosome arms is maintained in most of the species it has been suggested that Robertsonian fusion has been an important mechanism in the evolution of the Bracytheciaceae, and probably in all Diplolepidous mosses. Polyploidy has also played an important role in speciation. Finally it has been proposed that n = 11 is the primary basic number in the Diplolepideae.     

Chromosome number and karyotype of Phaenospermateae and Duthieeae (Poaceae), with reference to their systematic implications

Recent molecular phylogenetic studies indicate that Phaenospermateae and Duthieeae are among the early diverging lineages of Pooideae and that they are closely related to each other. Here, we test this with cytotaxonomical data. The monotypic tribe Phaenospermateae, represented by Phaenosperma globosum, has a chromosome number of 2n = 2x = 24 and a fairly symmetric karyotype consisting of 22 median (m) and 2 submedian (sm) chromosomes varying in length between 1.8–3 μm. Duthieeae, represented by Duthiea brachypodium, Sinochasea trigyna, Stephanachne monandra and Stephanachne pappophorea, also share the chromosome number 2n = 2x = 24 and similar symmetric karyotypes with the chromosomes varying in length between 1.4–5 μm. Thus, the close relationship of Phaenospermateae and Duthieeae is corroborated.     

Comparative cytogenetics of six Indo‐Pacific moray eels (Anguilliformes: Muraenidae) by chromosomal banding and fluorescence in situ hybridization

A comparative cytogenetic analysis, using both conventional staining techniques and fluorescence in situ hybridization, of six Indo‐Pacific moray eels from three different genera (Gymnothorax fimbriatus, Gymnothorax flavimarginatus, Gymnothorax javanicus, Gymnothorax undulatus, Echidna nebulosa and Gymnomuraena zebra), was carried out to investigate the chromosomal differentiation in the family Muraenidae. Four species displayed a diploid chromosome number 2n = 42, which is common among the Muraenidae. Two other species, G. javanicus and G. flavimarginatus, were characterized by different chromosome numbers (2n = 40 and 2n = 36). For most species, a large amount of constitutive heterochromatin was detected in the chromosomes, with species‐specific C‐banding patterns that enabled pairing of the homologous chromosomes. In all species, the major ribosomal genes were localized in the guanine‐cytosine‐rich region of one chromosome pair, but in different chromosomal locations. The (TTAGGG)_n telomeric sequences were mapped onto chromosomal ends in all muraenid species studied. The comparison of the results derived from this study with those available in the literature confirms a substantial conservation of the diploid chromosome number in the Muraenidae and supports the hypothesis that rearrangements have occurred that have diversified their karyotypes. Furthermore, the finding of two species with different diploid chromosome numbers suggests that additional chromosomal rearrangements, such as Robertsonian fusions, have occurred in the karyotype evolution of the Muraenidae.     

CHROMOSOME MORPHOLOGY IN THE GENUS SAMBUCUS

Two basic chromosome karyotypes were found in the genus Sambucus. Chromosome numbers were observed to be 2n = 38 for S. callicarpa, S. cerulea, S. glauca, S. kamtschatica, S. melanocarpa, S. mexicana, S. miquelli, S. sibirica, and S. sieboldiana and 2n = 36 for S. simpsonii and S. williamsii. Measurements of 18 karyotypes are presented. The major differences between the two basic chromosome karyotypes can be explained as the result of a mis-division of a metacentric chromosome giving rise to two telocentric chromosomes, thus reducing the number of metacentrics from five to four and increasing the chromosome number from 2n = 36 to 2n = 38. Observed chromosome aberrations and aneuploidy may result from unstable telocentric chromosomes.     

Diversified chromosomal characteristics in Centropyge fishes (Pomacanthidae, Perciformes)

We studied karyotypes and other chromosomal markers such as C-banded heterochromatin and Ag-stained nucleolus organizer regions (Ag-NORs), in seven Centropyge fishes (Pomacanthidae, Perciformes). These results revealed diversified chromosomal characteristics in Centropyge species. Three species had 2n = 48 chromosomes, whereas four species had 2n = 52 chromosomes. Fundamental numbers showed a large variation from 48 to 82, particularly in the species with 2n = 52 chromosomes. In all the species, Ag-NORs were located in a single chromosome pair and C-bands were mainly distributed in the centromeric regions of most chromosomes, as commonly seen in teleostean fishes. However, these chromosomal markers showed species-specific variations and provided us with useful information that could help us in understanding chromosomal evolution. On the basis of these chromosomal characteristics, we infer the process of chromosomal evolution, which according to us involves an increase in chromosome number from 2n = 48 to 2n = 52 through centric fission or other mechanisms, and in fundamental number through pericentric inversion. In particular, karyotypic evolution involving the increase in chromosome number is an unusual event in the evolution of higher teleostean groups. Handling editor: K. Martens     

Chromosomal analysis of twelve species of Microhylidae (Anura) from Madagascar

The karyotypes of four species of Dyscophinae and eight species of Cophylinae were analyzed. The chromosome number was 2n=26 in all cases. Between the two subfamilies a difference in the form of the karyotype was observed; the chromosomes show a gradual decrease in length in the Dyscophinae, whereas in the Cophylinae the karyotype demonstrates a clear discontinuity of size between pairs 5 and 6.Chromosomal polymorphism was found in Plethodontohyla tuberata, the chromosomes of pair 4 were subtelocentric in the homozygous specimens, whereas this pair showed a subtelocentric and a submetacentric chromosome of equal length in the heterozygous one, suggesting a pericentric inversion. Although in the Cophylinae the chromosome number is constant, the number of chromosome arms is variable. Pericentric inversions seem to play an important role in the chromosomal evolution of the Cophylinae.     

Karyological Differences between Northern Dolly Varden Salvelinus malma malma and White Char Salvelinus albusfrom the Kamchatka River Basin

The karyotypes of northern Dolly Varden and white char, sympatrically inhabiting the Kamchatka River basin, were studied. The karyotype of Dolly Varden was stable: 2n= 78 andNF= 98 + 2, while in white char, polymorphism and mosaicism for the chromosome number were revealed: 2n= 76–79, NF= 98 + 2. Using a routine chromosome staining technique, the karyotype of white char (2n= 78) was shown to be identical to that of Dolly Varden. In both karyotypes, similar sets of marker chromosomes were present: two pairs of submetacentric (SM), one pair of submeta-subtelocentric (SM-ST), one pair of large acrocentric (A), and one pair of large subtelocentric (ST) chromosomes. However, the karyotypes of Dolly Varden and white char differed in the number and location of nucleolus organizer regions (NORs). In Dolly Varden, single NORs located in the telomeric regions of the marker SM-ST chromosomes were observed. In white char, NORs were multiple and located both in the telomeric regions of the marker SM-ST chromosomes and on the short and long arms of large ST chromosomes. The identical marker chromosomes indicate considerable phylogenetic relatedness between Dolly Varden and white char from the Kamchatka River basin. Variation in NORs provides evidence for the reproductive isolation of these chars and their species status.     

Karyomorphological studies onWoodwardia sensu lato of Japan

Karyomorphological comparisons were made of five species of JapaneseWoodwardia. There were no marked differences at interphase and prophase among the five species.Woodwardia japonica, W. prolifera, andW. unigemmata were diploid with 2n=68 and the formulas of their metaphase karyotypes uniformly 4m(median centromeric chromosomes)+12sm(submedian)+52(st+t)(subterminal and terminal).Woodwardia orientalis was tetraploid with 2n=136 and 8m+24sm+104(st+t), and the ratio of each chromosomal type to total complement was identical to that of three diploid species. These four species had several characteristics in common:x=34, the longest chromosome of sm, and a mean chromosome length over 3.0 μm. AlthoughWoodwardia orientalis showed some similarity toW. prolifera, it seems to be an allotetraploid which originated by chromosome doubling of a hybrid ofW. prolifera and a diploid species as yet karyomorphologically unknown.Woodwardia kempii was tetraploid with 2n=124 and 8m+24sm+92(st+t), and differed from the others in havingx=31, the longest chromosomes of t, and a mean chromosome length under 3.0 μm. This species has been classified as an independent genus,Chieniopteris, and our karyomorphological study supports this treatment.     

The karyotypes of the thorny catfishes <Emphasis Type="Italic">Wertheimeria maculata</Emphasis> Steindachner, 1877 and <Emphasis Type="Italic">Hassar wilderi</Emphasis> Kindle, 1895 (Siluriformes: Doradidae) and their relevance in doradids chromosomal evolution

We studied the karyotypes of two doradids, the rare and endangered Wertheimeria maculata and a derived Amazonian species, Hassar wilderi. Cytogenetic characterization was assessed using conventional staining (Giemsa), C-banding, and NOR banding. Both species had 2n = 58 chromosomes but differed in their chromosome formulae, 24 m + 14sm + 8st + 12a for W. maculata and 32 m + 16sm + 10st for H. wilderi. In W. maculata heterochromatin was mainly telomeric, and three chromosomes had a fully heterochromatic arm; in H. wilderi heterochromatin was also predominantly telomeric and evident in many more chromosomes. Hassar wilderi also presented one pair of homologues with a fully heterochromatic arm. In both species, nucleolar organizer regions were restricted to one pair of subtelocentric chromosomes. Assuming a basal position for W. maculata, we hypothesized that underlying conserved diploid and NOR-bearing chromosome numbers, chromosomal evolution in doradids has involved pericentric inversions and an increase of heterochromatic blocks.     

The Giemsa banding patterns of the standard and four reconstructed karyotypes of Vicia faba

The Giemsa banding patterns of the standard karyotype of Vicia faba and of four new karyotypes with easily interdistinguishable chromosomes due to interchanges and inversions are described and compared with the data of other authors on preferential Giemsa staining in Vicia faba. All karyotypes contain 14 easily reproducible marker bands which characterize chromosome segments known to be heterochromatic. It is shown that the preferential Giemsa staining of chromosome regions is a valuable tool for the localization of translocation and inversion points in the chromosomes of the reconstructed Vicia karyotypes. A close correlation exists between banding patterns, segment extension by incorporation into chromosomal DNA of azacytidine and mutagen-specific clustering of induced chromatid aberrations in the new karyotypes.     

Comparative Genome Analysis in Two Flax Species by C-Banding Patterns

C-banding patterns of the karyotypes of two closely related wild flax species, Linum austriacumL. (2n= 18) and Linum grandiflorumDesf. (2n= 16), were studied. The karyotypes of both species were similar in the chromosome morphology and size. In each species, metacentric and acrocentric chromosomes (1.7–4.3 m) and one satellite chromosome were observed. In the karyotypes of the species studied, all homologous chromosome pairs were identified, and quantitative idiograms were constructed. Eight chromosome pairs in the two species had similar C-banding patterns. A low level of intraspecific polymorphism in the intercalary and telomeric C-bands was shown in both species. The results indicate that the genomes of two flax species originated from one ancestral genome with the basic chromosome number of 8 or 9. Apparently, the duplication or loss of one chromosome with subsequent redistribution of the chromosome material in the ancestral form resulted in the divergence into two species,L. austriacumL. and L. grandiflorumDesf. A considerable similarity of chromosomes in these species provides evidence for their close phylogenetic relatedness, which makes it possible to place them in one section within the Linumgenus.     

两种羽叶菊属植物(菊科:千里光族)的细胞学研究及其系统学意义

该研究首次报道了滇羽叶菊和台湾刘寄奴的染色体数据。结果表明:两者的染色体数量都为48,核型公式均为2n=2x=36m+10sm+2st,与前人报道的刻裂羽叶菊的核型稍有不同。两者的染色体形态均由大到小逐渐变化,核型二型性不明显,但前者染色体明显比后者大。这说明羽叶菊属染色体基数确实应为x=24,且染色体大小在种间有较大差异。细胞学证据表明,该属与蒲儿根属中染色体基数为x=24的类群以及狗舌草属确实近缘。     

CHROMOSOME CYTOLOGY OF EUCHARIS,CALIPHRURIA, AND URCEOLINA (AMARYLLIDACEAE)

Karyotypes are presented for 19 taxa of Eucharis, Caliphruria, and Urceolina, a monophyletic group of Andean Amaryllidaceae within “infrafamily” Pancratioidinae Traub. All three genera are characterized by 2n = 46, the most common somatic number occurring in the “infrafamily.” Incidences of polyploidy are low. Only two tetraploid (2n = 92) species of Eucharis are so far known, E. bouchei and E. bonplandii, the northernmost species of E. subg. Eucharis. The 2n = 68 karyotype of E. amazonica is interpreted as triploid-derived (3x – 1). Chromosomal heteromorphism is reported for C. subedentata. Karyotype data is analyzed with principal component analysis and unweighted pairgroup cluster analysis. In a number of cases, phenetic relationships among the karyotypes correlate with phenetic and cladistic relationships based on morphological data. Karyotype evolution among the three genera is discussed in the context of classical theories of karyotypic symmetry. Stability of chromosome number in Eucharis and related genera suggests that chromosomal evolution has proceeded via nonreciprocal interchanges between chromosomes and infrachromosomal structural change. In at least one case (E. bakeriana), rapid sympatric speciation may have been vectored by chromosomal change.     

Karyotypes of the most primitive catfishes (Teleostei: Siluriformas: Diplomystidae)

Karyotypes of Diplomystes composensis and Diplomystes nahuelbutaensis were the same diploid number (n= 56).The chromosome formula for D. composensis was 16 metacentric + 24 submetacentric + 8 subtelocentric + 8 telocentric chromosomes and for D. nahuelbutaensis was 14 metacentric + 26 submetacentric + 8 subtelocentric +8 telocentric chromosomes. In contrast, the differences in the chromosomal C-banding patterns between these species was large. For instance, chromosome pairs 5,6, and 7 of D. nahuelbutaensis showed heterochromatic centromeres and pairs 23, 24, 27, and 28 were entirely heterochromotic. Diplomystes composensis showed conspicuous C-banded blocks in pairs 7, 24, and 25 (chromosome pair 7 had one heterochromatic arm, chromosome pair 24 was entirely heterochromatic, and chromosome pair 25 had heterochromatin close to centromere). Comparison with other ostariophysan karyotypes (e.g. gymnotiforms, characiforms, and cypriniforms), does not allow any conclusions about the ploesiomorphic catfish condition, because the karyotypes of the outgroups are too variable. A synapomorphy shared by characiforms, gymnotiforms, and diplomystid catfishes is the presence of more metacentric to submetacentric than substelocentric to telocentric chromosomes. Cypriniforms are more primitive because they have more subtelocentric to telocentric than metacentric to submetacentric chromosomes.     

Karyotypes,nucleoli, and amphiplasty in hybrids between Hordeum vulgare L. and H. bulbosum L.

Chromosome measurements were carried out in Hordeum vulgare, H. bulbosum, and their diploid, triploid, and tetraploid hybrids. The chromosomes were classified by using relative values, and thus karyotypes were established. For comparison of these karyotypes both relative and absolute values were used. It was concluded that differential amphiplasty occurred, whereas neutral amphiplasty could not be demonstrated. In the hybrids the relative length of the parts of the chromosomes (long arm, short arm, satellite) was not changed in comparison with these lengths in the pure species. The karyotypes of both species had considerable similarities. From comparing the mean absolute genome lengths, it was, however, concluded that in the pure species, as well as in all hybrid types, the chromosomes of H. vulgare were longer than those of H. bulbosum. In the diploid and tetraploid hybrids the mean genome lengths were shorter than those in the pure species and the triploid hybrids. The differential amphiplasty was such that the secondary constriction of chromosome 6 of H. bulbosum, did not show up in the hybrids. This could be related to the suppression of nucleolar formation in the genome of H. bulbosum, because the maximum number of nucleoli in root tip cells equalled the number of satellite chromosomes. Finally it was found that the pattern of nucleolar fusion in diploid and triploid hybrids deviated from the expectation. The results were discussed in relation to chromosomal disturbances that occurred in the hybrid tissues and that resulted in elimination of chromosomes and other effects.     

Karyotype analysis and DNA content in some species of Chrysolaena (Vernonieae,Asteraceae)

Cytogenetic characterization by karyotyping and determination of DNA content by flow cytometry of five species of Chrysolaena (Vernonieae, Asteraceae) was performed. This is the first study of nuclear DNA content realized in the genus. The 2C-values were compared with the ploidy level and the total karyotype length (TKL) of each species. Mitotic analysis revealed a base chromosome number x = 10 for all entities and different ploidy levels, from diploid (2n = 2x = 20) to octoploid (2n = 8x = 80). All species showed bimodal karyotypes composed of metacentric and submetacentric chromosomes. The average chromosome size (ML) varied from 1.86 μm to 2.70 μm, while the TKL ranged from 18.65 μm to 80.55 μm. The intrachromosomal asymmetry index (A₁) varied from 0.27 to 0.38, while the interchromosomal asymmetry index (A₂) ranged from 0.19 to 0.25. A new cytotype is reported for the first time for C. propinqua. Accessory chromosomes found in C. verbascifolia, C. cognata, C. flexuosa, and C. propinqua are also reported as new.