Submetacentric Pair Research Articles

Karyotype characterization of Argania spinosa (L.) Skeel (Sapotaceae)

Argania spinosa (L.) Skeel is an endemic species from Southwest Morocco being the unique representative of the tropical Sapotaceae in this area. The cytology of this species is poorly known in spite of its great socio-economical and ecological interest in these arid and semi-arid zones. The objective of this work is to characterize the karyotype of A. spinosa species in somatic cells from root tips. Samples analyzed showed a karyotype constituted for ten pairs of chromosomes (2 n = 2 x = 20) and the putative karyotype proposed has been of four submetacentric and six metacentric pairs. The four submetacentric pairs were the longest with a mean total length between 1.14 and 1.69 μm and the total length of six metacentric pairs were between 0.59 and 1.03 μm.

Karyotype with 210 chromosomes in guaraná (Paullinia cupana ‘Sorbilis’)

The genus Paullinia includes the economically important P. cupana, known as guaraná in Brazil and more recently in the world market. Native Americans of the Maué and Andirá tribes cultivated P. cupana 'Sorbilis' in central Amazon, and the Barés cultivated the 'Typica' variety in the upper Negro River (Brazil). Cytological studies in the Sapindaceae family have concentrated on the diversity in number (from 2n = 14 to 96) and size of the chromosomes. In Paullinia, seven species have been karyotyped and all show 2n = 24. Meristem maceration, cellular dissociation and air-drying techniques were used for cytogenetic preparations and DNA content was determined by flow cytometry. Chromosome characterization and DNA content of Paullinia cupana Kunth 'Sorbilis' (Mart.) Ducke (Sapindaceae) were studied. The high chromosome number (2n = 210) fall into two cytomorphological groups: (a) a metacentric and submetacentric group showing 25 sets of three pairs of chromosomes (2-76); (b) a group containing only acrocentric showing 12 sets of two pairs of chromosomes (82-105), a homologous submetacentric pair (1) and an acrocentric pair (81). Mean nuclear DNA content of guaraná was 2C = 22.8 pg. A karyogram was set up showing a high chromosome number complement.

Multicolor fluorescence in situ hybridization with combinatorial labeling probes enables a detailed karyotype analysis of Larix principis-rupprechtii

The chromosomes (2n = 2x = 24) of Larix principis-rupprechtii are composed of six pairs of large metacentrics and six pairs of medium-sized submetacentrics. The identification of homologous pairs is hampered by their high degree of similarity at the morphological level in each group. As one of the most extensively used methods in molecular cytogenetics producing chromosome landmarks, fluorescence in situ hybridization (FISH) has significantly facilitated karyotype construction, especially in species with morphologically similar chromosomes. This study developed a simple but effective use of combinatorial labeling probes to distinguish chromosomes of Larix principis-rupprechtii by multicolor FISH. Three highly repetitive sequences in Larix were selected: 25S rDNA hybridized at all of the secondary constrictions of two pairs of metacentrics and the largest pair of submetacentrics; 5S rDNA hybridized at subtelomeric sites of one pair of metacentrics that also harboured 25S rDNA on different arms; LPD family sequences are tandem repeats hybridized at proximal regions of 22 chromosomes. The three different probes were labeled with only two different labels, hybridized to metaphase chromosomes of Larix principis-rupprechtii, simultaneously visualized, and unequivocally distinguished in a single FISH experiment. These multicolor FISH marks largely improved the karyotype analysis of Larix principis-rupprechtii.

Cytogenetics and Flow Cytometry-based DNA Quantification in Herreria salsaparilha Martius (Herreriaceae): a Medicinal Species

Summary Adventitious root tips developing from base of cuttings and leaf samples of Herreria salsaparilha were used to determine the karyotype and to estimate DNA amount, respectively. Flow cytometry methodology was used with DAPI (4� ,6-diamidino-2-phenylindole) and PI (propidium iodide) as specific DNA fluorochromes, and leaf samples of Pisum sativum (9.09 pg) as an internal standard. Cytogenetic techniques determined that H. salsaparilha has 29 pairs of homologous chromosomes (2n� 58), 12 acrocentric pairs (length varying from 1.75 to 10.51 mm), 16 submetacentric pairs (1.30 to 3.45 mm), and 1 metacentric pair (2.8 mm). The DAPI- and PI-based flow cytometry analysis revealed that H. salsaparilha has nuclear DNA content 2C� 5.5 pg, equivalent to approximately 5.31� 10 9 base pairs. This karyotype asymmetric type may suggest an evolutionary process with involvement of polyploidization, being justified by the relative increased chromosome number (2n� 58) and fusions.

Cytogenetic characterization of Lippia alba and Lantana camara (Verbenaceae) from Brazil

The aim of this work was to determine the cytogenetic characteristics of Brazilian Lippia alba (Mill) N. E. Brown and Lantana camara Plum. that could be useful for future characterization of these genera. Our analyses revealed that Li. alba has 2n=30 chromosomes consisting of ten metacentric and five submetacentric pairs, while La. camara has 44 metacentric chromosomes. The large blocks of heterochromatin seen in both species suggest an apomorphic condition. Six 45S rDNA sites were detected in both species by fluorescence in situ hybridization (FISH). Two and four 5S rDNA sites were observed in Li. alba and La. camara, respectively. Meiotic analysis revealed a normal chromosomal behaviour. The number of chromosomes and the presence of 45S rDNA and 5S rDNA sites do not exclude a possible polyploid origin. The cytogenetic differences between La. camara and Li. alba may be useful markers for differentiating these species.

Taxonomic study of the water shrewsChimarrogale himalayica andC. platycephala

We investigated karyotypes, mitochondrial cytochromeb gene sequences, and cranial morphometries of the water shrewsChimarrogale himalayica (Gray, 1842) andC. platycephala (Temminck, 1842) (Insectivora, Soricidae). Karyotypes ofC. himalayica from Taiwan andC. platycephala are 2n=52 and FNa=100. Autosomes consisted of 21 large-to-small metacentric or submetacentric pairs, and 4 medium-to-small subtelocentric pairs. The X and Y chromosomes were medium submetacentric and small acrocentric, respectively. The karyotypes ofC. himalayica andC. platycephala were very similar. Secondary constrictions were observed in the largest metacentric pair in both species. In the 930 base-pairs of the cytochromeb gene,C. himalayica from Taiwan andC. platycephala diverged with 9.46% sequence difference; each species diverged fromC. phaeura with more than 14% sequence difference. The two speciesC. himalayica andC. platycephala were well distinguished by morphometric characters, but three subspecies ofC. himalayica were not clearly separated. We suggest thatC. platycephala be treated as a valid species and separated fromC. himalayica in Taiwan.

Fluorescence in situ hybridization of rDNA, telomeric (TTAGGG)n and (GATA)n repeats in the red abalone Haliotis rufescens (Archaeogastropoda: Haliotidae)

The physical location of 18S-5.8S-28S rDNA, telomeric sequences with (TTAGGG)n DNA probe and (GATA)n microsatellites were performed by fluorescence in situ hybridization in chromosomes of red abalone Haliotis rufescens. The karyotype of red abalone showed a diploid number of 36 (8M+9SM+1ST). FISH performed with rDNA probe, showed the location of major ribosomal clusters in the terminal region of the large arms of two submetacentric pairs (chromosome 4 and 5). Localization of heteromorphisms of FISH-rDNA was found between chromosome homologues and sister chromatids in all metaphases analyzed. This indicates that rDNA clusters are variable within the red abalone genome. The variability in the NOR-bearing reported using silver staining in other gastropods and our result are discussed. In addition, the presence of microsatellite (TTAGGG)n and (GATA)n was demonstrated after FISH treatment by DNA probes. The telomeric sequence occurred at the ends of all mitotic chromosomes, while the (GATA)n repetitive was found on chromosomal interstitial zones as well as at the telomeres in abalone chromosomes.

Cytogenetic analysis on Pterophyllum scalare (Perciformes, Cichlidae) from Jari River, Pará state

Cytogenetic studies were carried out on eighteen wild specimens of Pterophyllum scalare from Jari River, in Parastate, and the results were compared to literature. Mitotic chromosomes were obtained from kidney cells and the analysis was done using: C-banding, Ag-NOR staining, Chromomycin A3/DAPI sequential staining and fluoro- chrome in situ hybridization with human telomere probes. All individuals showed a chromosome number of 2n = 48 (12 M/SM and 36 ST/A) and FN = 60. No differences were detected between male and female karyotypes, indicating the absence of morphologically differentiated mitotic sexual chromosomes. Constitutive heterochromatin blocks were located at the centromeric and pericentromeric regions of all chromosomes. The largest submetacentric pair showed a differential staining on their short arms. Only two NOR bearing chromosomes were detected, and the stainings were observed at the distal region of the short arm of the largest chromosome pair, matching the secondary constriction. Chromomycin A3 stained the NOR and the centromeres of some chromosomes. DAPI-bands were ob- served at the centromeric regions of all chromosomes. Telomere sequences hybridised only at the terminal regions.

Karyotype and nuclear DNA content of Trichomycterus areolatus (Siluriformes, Trichomycteridae)

Cytogenetic analysis of Trichomycterus areolatus, collected from the Tijeral and Huilma Rivers in southern Chile has shown a diploid chromosome number of 2n = 54, a fundamental number of FN = 106, and a karyotypic formula of 44m + 8sm + 2st. Intra-individual polymorphism of chromosome number (2n = 54, 55 and 56) in specimens from the Huilma River has also been documented, providing further evidence of the occurrence of this phenomenon in Trichomycterus. The karyotype exhibited large chromosome pairs: metacentric pairs 1 (relative length 7.54%), 2 (5.75%) and 3 (5.09%), submetacentric pair 23 (5.25%), and subtelocentic pair 27 (5.28%). Nuclear DNA content analysis showed an average value of 5.04 ± 1.09 pg/nucleus. This DNA content is higher than the mean value described for other species in this genus.

Molecular characterization and chromosomal mapping of the 5S rRNA gene in Solea senegalensis: a new linkage to the U1, U2, and U5 small nuclear RNA genes

Some units of the 5S rDNA of Solea senegalensis were amplified by PCR and sequenced. Three main PCR products (227, 441, and 2166 bp) were identified. The 227- and 441-bp fragments were characterized by highly divergent nontranscribed spacer sequences (referred to as NTS-I and NTS-II) that were 109 and 324 bp long, respectively, yet their coding sequences were nearly identical. The 2166-bp 5S rDNA unit was composed of two 5S rRNA genes separated by NTS-I and followed by a 1721-bp spacer containing the U2, U5, and U1 small nuclear RNA genes (snRNAs). They were inverted and arranged in the transcriptional direction opposite that of the 5S rRNA gene. This simultaneous linkage of 3 different snRNAs had never been observed before. The PCR products were used as probes in fluorescence in situ hybridization experiments to locate the corresponding loci on the chromosomes of S. senegalensis. A major 5S rDNA chromosomal site was located along most of the short arm of a submetacentric pair, while a minor site was detected near the centromeric region of an acrocentric pair.

English

Chromosome counts from natural populations of Abrus pulchellus in Nigeria were carried out. Tetraploid (2n = 44) chromosome number was constant in all the samples investigated. The 44 chromosomes fall into three cytomorphological categories: eight metacentric and eight submetacentric pairs, and six acrocentric pairs. The chromosomes are relatively small in length ranging from 0.5 to 1.4m. The polyploid (tetraploid) cytotype is reported for the first time for this taxon. African Journal of Biotechnology Vol. 4 (7), pp. 607-610, 2005

Comparative cytogenetics of Hoplias malabaricus (Pisces, Erythrinidae): a population analysis in adjacent hydrographic basins

The chromosomes of specimens from four Hoplias malabaricus populations from headwaters of adjacent river basins at Ponta Grossa, southern Brazil, were investigated using differential staining techniques (C-banding, AgNO3 and CMA3) and fluorescent in situ hybridization (FISH) with an 18S rDNA probe. The diploid chromosome number in representatives of all four populations was invariably 2n = 42, with karyotypes composed of 12 pairs of metacentrics and 9 pairs of submetacentrics, without heteromorphic sex chromosomes. This kind of karyotype represents cytotype A in regard to cytotypes identified previously in H. malabaricus, exhibiting however, at the same time, some differences in the distribution of constitutive heterochromatin segments and in the locations of nucleolus organizer regions (NORs). The apparent karyotype similarity strongly suggests a close kinship among the studied populations, but the small differences detected in the examined chromosomal markers indicate some evolutionary divergence due to gene flow restriction among them.

A note on karyotypes ofSorex caecutiens(Mammalia, Insectivora) from Cheju Island, Korea

Abstract Karyotypes of Sorex caecutiens from Cheju Island of Korea were examined with conventional staining and G-banding by trypsin treatment stained with Giemsa (GTG). The diploid and fundamental autosomal arm numbers were 42 and 66, respectively. The autosomal complement in the karyotype comprised six pairs of metacentrics, seven pairs of submetacentrics or subtelocentrics, and seven pairs of acrocentrics. The X was a largest acrocentric chromosome, and the Y was a small subtelocentric chromosome. Chromosomal constitutions and G-banding pattern of S. caecutiens from Cheju Island were essentially identical to those reported for S. shinto from Honshu Island, Japan. This similarity may indicate the ancestral character of the monophyletic S. caecutiens/shinto group.

G-, C-, and NOR-stained karyotype of the Eversmann's hamster Allocricetulus eversmanni and comparison with the karyotype of Cricetulus species (Rodentia: Cricetinae)

Differential chromosomal stainings for various species belonging to genera in the tribe Cricetini of the Eurasian Cricetinae including Cricetus, Cricetulus, Tscherskia, Phodopus, and Mesocricetus are available (Gamperl et al. 1978; Kartavtseva et al. 1979; Popescu and DiPaolo 1980; Kral et al. 1984). Hitherto, however, no differential chromosomes stainings for species in the genus Allocricetulus have been described and the phylogenetic position of this genus in the Cricetini, based on chromosomal data, has not been determined. The Eversmann’s hamster Allocricetus eversmanni Brandt, 1859 occurs in dry steppes and semi-deserts between the Volga and Ural rivers in Russia and in Kazakhstan, and includes three subspecies. The karyotype of A. eversmanni (2n = 26) was first described by Matthey (1960) from Kazakhstan, then subsequently those for subspecies, A. e. eversmanni and A. e. beljaevi (2n = 26, NF = 40: 8M + 10T + 6ST, X – SM, Y – SM) and A. e. pseudocurtatus (2n = 26; NF = 38: 8M + 12T + 4ST, X – M/SM, Y – SM/ST) were described. Kartavtseva and Vorontsov (1992) found distinctions in the morphology of one pair of large autosomes, pair no. 5, and in the size and morphology of the Y-chromosome and have suggested that the difference in the chromosome pair no. 5 appeared in A. e. pseudocurtatus. One female A. e. eversmanni was captured in the vicinity of Djakovka Village, Saratov Region, near the Lower Volga River, Russia. Chromosome preparations were obtained from bone marrow cells. After colcemidtreatment and hypotonic treatment with KCl-solution, the cells were fixed with acetic-methanol (1 : 3) and air or flame-dried. We arranged the chromosomes as described previously by Kartavtseva and Vorontsov (1992). The procedure of tripsin treatment was used for G-banding (Seabright 1971). The distribution of heterochromatin in chromosomes was shown using Sumner’s (1972) modified C-banding technique. The locations of nucleolar organizer regions (NORs) of metaphase chromosomes were determined after 50% aqueous AgNO3 treatment for 12 hours at 50–60°C (Bloom and Goodpasture 1976). The karyotype consisted of 24 autosomes (2n = 26, NF = 40): four pairs of metacentrics (M) and submetacentrics (SM): one pair large, one pair medium and two pairs small, two pairs of large subtelocentrics (ST) and six pairs of acrocentrics (A), ranging from medium-sized to small. The X chromosome was a medium sized submetacentric (Fig. 1). Differential G-staining made it possible to define the homologues in the karyotype (Fig. 1a). The short arm of the large subtelocentric no. 5 had no clear bands, while the short arm of the large subtelocentric no. 6 had a clear band in the pericentromeric region. The least acrocentrics nos. 11 and 12 had no clear bands. The C-staining of chromosomes obtained a low amount of heterochromatin in A. e. eversmanni in biarmed chromosomes nos. 1, 2, 5, 6, and acrocentric no. 7 had no positive band. The two pairs of small metacentrics nos. 3, 4 and small acrocentrics nos. 8–12 had heterochromatin in pericentromeric areas. The X chromosome carried one dark C-block in the pericentromeric region of the short arm (Fig. 1b). NORs were ascertained in five pairs of chromosomes. In pairs 2, 4, and 5 of biarmed chromosomes, the NORs were found at the telomeric ends (pair 5 had NORs in short arms). In the acrocentric pairs 8 and 10, very small NORs were observed at the centromeric positions (Fig. 1c). Earlier we assumed that distinction among A. e. eversmanni, A. e. beljaevi and A. e. pseudocurtatus based on the occurrence of deletion in the short arm of

Intraspecific Karyotypical Diversity in Brackish Water Fishes of the Eleotridae Family (Pisces, Perciformes)

The Eleotridae family consists of 35 genera and 150 species distributed in freshwaters/brackish waters, estuaries or shores of tropical and subtropical regions. A few species are found in the Central America and South America. Cytogenetic analyses were performed on sympatric species Dormitator maculatus (12 individuals; 9 males and 3 females) and Eleotris pisonis (5 individuals; 2 males and 3 females) collected in the lower course of the Pium River, Northeastern Brazil. Both the species have 2n=46 with striking differences for the chromosome formulas (D. maculatus, 40m-sm+6st-a and E. pisonis, 46a). The two species revealed preferentially centromeric or telomeric heterochromatic regions and absence of structural chromosome heteromorphisms between the sexes. The NORs are located on the short arm of a submetacentric pair (pair 4) in D. maculatus and in intersticial position on a medium acrocentric (pair 21) in the E. pisonis. Meiotic analyses carried out on D. maculatus and E. pisonis showed a modal value of 23 in both MI and in MII. Comparison with cytogenetic data of Mexican populations (D. maculatus, 34m-sm+12st-a; E. pisonis, 2m-sm+42st-a) indicated that the karyotypical changes among the populations from Northeastern Brazil and the Mexican coast are mainly due to pericentric inversion, although translocations, fission and fusion are involved in the karyotypic diversification of the group. The differences observed among the karyotype macrostructure of South and Central American forms suggest the existence of distinct species in these two regions.

The karyology of the cyprinid genera Scardinius and Rutilus in southern Europe

The chromosomes of eight species of Rutilus and Scardinius, mostly endemic to the Italian and the Balkan peninsula, were analyzed by conventional and other banding techniques. Parallel analyses were conducted also on two leuciscine species, Alburnus albidus, for which we provide the first karyological analysis, and Leuciscus cephalus. All species examined displayed the same karyotype (2n = 50 chromosomes, 8 metacentric + 13 submetacentric + 4 subtelo/acrocentric pairs) with nucleolus organizer regions (NORs) on the ends of the shorter arms of a medium-sized submetacentric pair. In contrast, interspecific variation was observed in the distribution of constitutive heterochromatin. The variation observed in this genomic material proved to be systematically and phylogenetically informative. Indeed, a peritelomeric C-band on the first telocentric pair characterizes species of Rutilus and Scardinius. In both genera heterochromatin differentiation appears to be directed to a centromere–telomere direction, particularly evident along the metacentric elements of their karyotypes.

Giemsa C-Banded Karyotypes of two Cytotypes (2x, 4x) of Psathyrostachys Lanuginosa (Poaceae; Triticeae)

The karyotypes of the diploid (2n = 2x = 14) and tetraploid (2n = 4x = 28) cytotypes of the outbreeding P. lanuginosa collected from one population in China were investigated by Giemsa C- and N-banding and AgNO3 staining. The complement of the diploid consisted of 14 large chromosomes: 8 metacentrics and 6 SAT-chromosomes, one metacentric and 2 submetacentric pairs, with small to minute, polymorphic, completely heterochromatic satellites. Except that only eight SAT-chromosomes were observed, the complement of the tetraploid matched a doubling of that of the diploid and indicated an autoploid origin. The existence of 12 chromosomes with nucleolus organizers was established through AgNO3 staining demonstrating nucleoli. C-banding patterns comprised from zero to three (2x), or four (4x) small bands per chromosome giving a low content of constitutive heterochromatin (< 3 percnt;). The level of banding pattern polymorphism was low. N-banding produced no bands. Variation in the size of nucleoli demonstrated a differential nucleolus forming capacity of nucleolus organizers among SAT-chromosomes. The basic karyotype was similar to those of P. fragilis, P. juncea and P. stoloniformis, indicating a close relationship and the presence of genome N. Meiotic analysis suggested the presence of a chromosomal rearrangement in the diploid. The frequency of interstitial chiasmata was high. Differences in pollen diameters differentiated the two cytotypes.

Replication, C- and Fluorescent Chromosome Banding Patterns in European Whitefish, Coregonus Lavavetus L.

The chromosome complement of Curegunus luvaretus was investigated using C-banding, DAPI and CMA,3 fluorescent stainings, and replication banding techniques. Diploid chromosome number was 2n = 80, and the arm number was NF = 100. Karyotype consisted of 8 pairs of metacentrics, 2 pairs of submetacentrics, 2 pairs of subtelocentrics and 28 pairs of acrocentrics, gradually decreasing in size, and of 0–4 supernumerary chromosomes. Chromomycin A3 staining revealed the location of nucleolar organizer regions (NORs), showing that examined fish possessed two pairs of submetacentric-subtelocentric (sm-st) NOR-bearing chromosomes. Staining with DAPI revealed the distribution of AT-rich regions. The use of in vivo 5-bromodeoxyuridine (BrdU) incorporation technique induced highly reproducible replication bands. All banding patterns obtained in the study allowed identification of numerous chromosome pairs in the Coregonus lacaretus karyotype. Chromosome 1 showed individual variation in the amount of C-positive heterochromatin resulting in the length polymorphism of this pair. Replication banding pattern in European whitefish showed differences between three forms of the first chromosome pair.

Chromosomal and Allozyme Characterization of the Caucasian Shrew, Sorex Satunini, from North-Eastern Turkey

Fifteen individuals of the Caucasian shrew, Sorex satunini, from five sites in north-eastern parts of Asian Turkey were examined. All the shrews were studied by starch gel electrophoresis whereas 7 animals from 3 localities were karyotyped. The diploid number of autosomes was 2na= 22; there was one pair of large metacentrics, one pair of large submetacentrics, four pairs of medium-sized meta-/submetacentrics, four pairs of small biarmed elements, and a single pair of small acrocentrics in the diploid karyotype (NFa= 42). The sex chromosomes made up a standard XX bivalent in females and an XY1Y2 trivalent in males. Out of 36 allozyme loci scored, seven were found to be polymorphic in at least one population of S. satunini. One locus appeared to be discriminant and three other loci were partially discriminant between the Caucasian shrew and S. araneus. Indices of genetic variability, i.e., mean number of alleles per locus (A), frequency of polymorphic loci (P5%), and mean heterozygosity (Hc) displayed rather low values in all the samples of the Caucasian shrew under study. Moreover, Nei's genetic distances within the Turkish S. satunini were found to be extremely low (0.000-0.001). The electrophoretical results were then compared with previously published data from the Czech Republic, Slovenia and Macedonia at 27 loci. The genetic distances between populations of the two species appeared to range between 0.052 and 0.110.

The Karyotype of Elymus Mendodnus (Poaceae; Triticeae) from Argentina studied by Banding Techniques

The karyotype of Elymus mendodnus (2n = 8x = 56) was investigated by Giemsa C-banding and N-banding, and AgNO3 staining. The chromosomes were large (7–13 μm). The chromosome complement consisted of 22 metacentric and 6 submetacentric pairs. Two metacentric and one submetacentric pairs had satellites on the short arms. One of the metacentric pairs had large satellites. The other satellites were small. The number of SAT-chromosomes was verified through AgNO3 staining confirming the presence of up to 6 nucleoli at interphase. The C-banding pattern comprised small to large C-bands at telomeric positions in all short arms except one and in most of the long arms. A few, mostly small bands were located at distal, intercalary positions. The small satellites were entirely heterochromatic. The amount of constitutive heterochromatin (14 %) was among the highest recorded in the Triticeae. Except in 12 chromosome pairs, incl. the 3 satellited ones, the overall similarity of the C-banding patterns of most chromosomes prevented a safe identification of homologues. Additionally, the level of identified banding pattern polymorphism was low, but supports an outbreeding nature of the species. N-banding produced no bands. A similar distribution of large C-bands and lack of N-banding have previously been observed in Psathyrostachys huashanica. This agrees with the presence of the Ns genome and the absence of the H genome in E. mendodnus (DUBCOVSKY et al. 1997), and suggests the absence of the pivotal St genome of Elymus. However, lacking further evidence we propose to retain the species in Elymus.