Small Submetacentric Chromosomes Research Articles

Karyomorphological delineation and linear differentiation of microsatellite patterns, and meiosis in giant Asian river frog (Limnonectes blyhii) from Thailand

The present investigation provides information on linear chromosomal differentiation and microsatellite patterns [d(CA)15, d(CGG)10, d(TA)15] in the genome of giant Asian river frog (Limnonectes blyhii). Five male and female samples each collected from southern Thailand, were used for the study. The metaphase chromosome preparations were prepared from the bone marrow using the standard protocol. Results show that both male and female have the diploid chromosome number 2n = 24, and the fundamental number NF = 48. The karyotypes compose of 4 large metacentric, 4 large submetacentric, 2 medium metacentric, 8 small metacentric and 6 small submetacentric chromosomes. The Ag-NOR, FISH as well as hybridization with the microsatellite d(CGG)10 confirm the location of NOR site in the subcentromeric region on chromosome pair 11. The in situ localization pattern of d(CA)15 microsatellite was positive on chromosome pairs 1 and 6, while microsatellite d(TA)15 show its location in the long arm of chromosome 5,8 and 10. The information provided has value as species specific marker for this species.

Karyotypic Analysis of the Spined Toad, <i>Bufo spinosus</i> Daudin, 1803 (Amphibia: Bufonidae)

For the first time, somatic chromosomes of Bufo spinosus were described (2 n = 22). It was close to the karyotypes of other West-Palearctic species of the genus Bufo and consisted of 10 large metacentric ( V ), 2 large submetacentric chromosomes ( SV ), 8 small metacentric ( v ), and 2 small submetacentric chromosomes ( sv ): 10 V + 2 SV + 8 v + 2 sv , NF = 44. All chromosomes of B. spinosus were characterized by presence of heterochromatin blocks in centromeric regions. No Q-stained bright bands were found. Ag-staining detected a nucleolar organizer region in the end of the long arm of the sixth pair of chromosomes. In all males studied, a dimorphism was found in the sixth pair of chromosomes. One chromosome in this pair was smaller than the second one. Differences in position of nucleolar organizer region or centromeric index between these chromosomes were not revealed.

Karyotypic features including organizations of the 5S, 45S rDNA loci and telomeres of Scadoxus multiflorus (Amaryllidaceae).

Scadoxus multiflorus Martyn, 1795 is an ornamental plant with brilliantly colored flowers. Even though its chromosomes are rather large, there is no karyotype description reported so far. Therefore, conventional and molecular cytogenetic studies including fluorescence in situ hybridization (FISH) with 45S and 5S rDNA, and human telomere sequence (TTAGGG)n probes (Arabidopsis-type telomere probes yielded negative results) were carried out. The chromosome number is as reported previously, 2n = 18. The nine chromosome pairs include two large submetacentric, five large acrocentric, one medium acrocentric, two small metacentric and eight small submetacentric chromosomes. Hybridization sites of the 45S rDNA signals were on the short arm ends of chromosomes #1, #3 and #8, while 5S rDNA signals appeared on the long arm of chromosome 3, in one homologue as a double signal. The telomere signals were restricted to all chromosome ends. Three chromosome pairs could be newly identified, chromosome pair 3 by 5S rDNA and chromosomes #1, #3 and #8 by 45S rDNA loci. In addition to new information about rDNA locations we show that the ends of Scadoxus multiflorus chromosomes harbor human instead of Arabidopsis-type telomere sequences. Overall, the Scadoxus multiflorus karyotype presents chromosomal heteromorphy concerning size, shape and 45S and 5S rDNA positioning. As Scadoxus Rafinesque, 1838 and related species are poorly studied on chromosomal level the here presented data is important for better understanding of evolution in Amaryllidaceae.

Comparison of chromosomal architecture of Sahiwal and crossbred Sahiwal cattle

The karyological investigation using 16 purebred Sahiwal and 16 Jersey X Sahiwal cattle (8 males and 8 females of each genetic group) revealed the diploid chromosome number to be 60. All the 29 pairs of autosomes were acrocentric, while the X – chromosome was sub-metacentric in both the genetic groups. Acrocentric Y chromosome of Sahiwal differed from small submetacentric chromosome of Jersey X Sahiwal cattle in its morphology. The relative length of autosomes ranged from 1.74 ± 0.01 to 5.28 ± 0.02 in Sahiwal and from 1.72 ± 0.01 to 5.26 ± 0.02 in Jersey X Sahiwal crosses. X – Chromosome was the second largest chromosome in both the genetic groups. The contribution of X and Y chromosomes to the total genome were 5.07 and 1.99 per cent to the total genome in Sahiwal and 5.06 and 2.20 per cent in Jersey X Sahiwal cattle, respectively. The arm ratio, centromeric index and morphological index for the X-chromosome of Sahiwal and Jersey X Sahiwal cattle were 1.89, 0.35, 2.87 and 1.84, 0.36, 2.76, respectively. The arm ratio, centromeric index and morphological index for the Y-chromosome of Jersey X Sahiwal cattle were 1.63, 0.35 and 1.41, respectively.

A Novel Unequal Reciprocal Translocation in the Karyotype Diversification of Vicia hybrida (Fabaceae)

In Viciahybrida (2n = 2x = 12) one out of twenty-five plants analyzed was found to be heterozygote for highly unequal translocation but with a difference and novelty. All the cells analyzed at metaphase I were characterized by the presence of a ring or a chain of four chromosomes. The two derived chromosomes in the heterozygote were of highly unequal size, one being very long metacentric and another very small submetacentric chromosome. The two other ancestral submetacentric and subtelocentric chromosomes were medium sized with little difference in their lengths. The small derived chromosome was not totally heterochromatic, and it was associated with the complex heterozygote by the formation of chiasmata at one or at both ends. No cell was observed to be a trivalent and univalent. Majority (52 %) of cells at anaphase I were characterized by the occurrence of five and six chromosomes at each pole and the small derived chromosome lagging behind. In 64.1 % cells at telophase I, the small derived chromosome was found to lag behind with intact morphology without the process of decondensation. In 48 % cells at telophase II it was seen to divide. A new type of Robertsonian translocation is discussed in relation to the interchanged chromosome.

Karyotype of the Eichwald’s Toad, Bufo eichwaldi (Amphibia: Bufonidae)

For the first time the karyotype of Bufo eichwaldi was described (2n = 22). It consists of 12 large metacentric (V), 8 small metacentric (v), and 2 small submetacentric chromosomes (sv): 12 V + 8 v + 2 sv, NF = 44. According to the number of chromosomes and arrangement of NORs (in the end of long arms of pairs 6), the karyotype of B. eichwaldi has no differences from karyotypes of close related B. bufo and B. verrucosissimus. The main difference is wide heterochromatin C-blocks in long arms of pair 10, which is present in B. eichwaldi and lacking in B. bufo and B. verrucosissimus. Moreover, in the Eichwald’s toad the pair 1 has, as a rule, larger size if compare with other two species. Additionally, these two species had two submetacentric chromosomes (pairs 4 and 7), but B. eichwaldi had only one (pair 7).

Gene mapping of 28S rDNA sites in allotriploid Cobitis females (Pisces: Cobitidae) from a diploid-polyploid population

We performed cytogenetic analysis on triploid Cobitis hybrid specimens from a natural diploid-polyploid population in the Bug River (Poland). Chromosomes were examined by fluorescence in situ hybridization method (FISH) with 28S rDNA as a probe. The rDNA sites were commonly identified in the terminal position of p arms of two small submetacentric chromosomes, in the centromere area of two acrocentric chromosomes and in the terminal position of q arm of one acrocentric chromosome. Some of the observed signals were stronger than others. In few cases, one small acrocentric chromosome showing rDNA sites located terminally on both p and a q arm was observed. This study brings useful information about polymorphism of 28S rDNA sites regarding their number, location and size in triploid specimens. Moreover, it gives preliminary data for comparison with similar researches on the parental species of Cobitis hybrid females, viz. C. taenia, C. taurica and C. tanaitica, and other related Cobitis taxa of different ploidy level. The present study increases our knowledge about ribosomal genes inheritance between Cobitis species and their polyploid hybrids.

Polyploidy, B chromosomes, and heterochromatin characterization of Mimosa caesalpiniifolia Benth. (Fabaceae-Mimosoideae)

Eight populations of Mimosa caesalpiniifolia Benth. were investigated using a cytogenetic approach. Here, we describe for the first time details of the karyotype including chromosome morphology, physical mapping of chromomycin A3 (CMA) 4′,6-diamidino-2-phenylindole (DAPI) and silver staining of nucleolar organizer regions (Ag-NOR banding), as well as 45S rDNA sites. All populations studied showed karyotypes with 2n = 2x = 26 small metacentric and submetacentric chromosomes, although some individuals exhibited 2n = 4x = 52 chromosomes. Moreover, we observed putative additional B chromosomes in some populations. The CMA banding and fluorescent in situ hybridization techniques revealed NOR heteromorphism on the unique pair containing 45 rDNA site (chromosome 12) while the Ag-NOR banding indicated NORs on both cytotypes. Up to two and four nucleoli were observed, respectively, on individuals with 2n = 2x = 26 and 2n = 4x = 52 chromosomes and the differences in nucleolar size seems to be directly related to NOR heteromorphism in some individuals. The data present new and important information to understand karyotypic evolution of Mimosa and Fabaceae.

Cytogenetic characterization of Brycon amazonicus (Spix et Agassiz, 1829) (Teleostei: Characidae) from Caicara del Orinoco, Venezuela

A cytogenetic analysis by conventional Giemsa staining, silver staining, C-banding, and fluorescence in situ hybridization (FISH) was carried out on Brycon amazonicus from Caicara del Orinoco, Venezuela. The karyotype of this species is characterized by the presence of 2n = 50 chromosomes, a karyotypic formula 22m+14sm+14st, and a fundamental number of 100 chromosomal arms. Nucleolar organizer regions (NORs) and 18S rDNA genes are located in the terminal regions of the long arms of the second pair of subtelocentric chromosomes, corresponding to pair 13. C-banding revealed heterochromatin distribution in only seven chromosome pairs. The largest metacentric pair (number 1) possesses a paracentromeric block equilocally distributed in both chromosome arms, whereas in pairs 12 to 17 positive C band blocks were located in the paracentromeric region of the long arm, close to the centromere. Analysis performed with 5S rDNA gene revealed a terminal site located on the short arm of one small submetacentric chromosome (pair 15) corroborating previous studies with this repetitive gene showing an apparent conservation of 5S rDNA in the genome of these fish species. The data obtained in this study reinforce the chromosomal conservativeness in the species of the genus Brycon, related not only to the macro-chromosomal structure (diploid number, karyotypic formula, and fundamental number), but also to the repeated DNAs, such as heterochromatic regions and ribosomal DNAs. These data will contribute to a better understanding of chromosomal evolution in both Brycon and Characidae fishes.

Cytogenetic Study of the Leopard, Panthera pardus (Carnivora, Felidae) by Conventional Staining, G-banding and High-resolution Staining Technique

This is a cytogenetic study of the leopard, Panthera pardus (Carnivora, Felidae). Blood samples were taken from 2 males and 1 female. After the standard whole blood lymphocyte culture in the presence of colchicine, the metaphase spreads were performed on microscopic slides and air-dried. Conventional staining, G-banding and high-resolution staining technique were applied to stain the chromosomes. The results showed that 2n (diploid) of leopard was 38, and the fundamental number (NF) was 72 in the male and female. There are 6 autosome types: A type had 4 large submetacentric and 2 medium submetacentric chromosomes, B type had 4 large acrocentric and 4 medium acrocentric chromosomes, C type had 2 large metacentric and 2 medium metacentric chromosomes, D type had 8 small submetacentric chromosomes, E type had 6 small metacentric chromosomes and F type had 4 small telocentric chromosomes. A pair of the short arm of chromosome E1 (chromosome pairs 14) showed a clearly observable satellite chromosomes. The X chromosome was small submetacentric chromosome and the Y chromosome was the smallest submetacentric chromosome. From the G-banding and high-resolution staining technique, the number of bands and locations in the leopard was 163 and 191 respectively, and each chromosome pair could be clearly differentiated. We found that chromosomes A1, B3, B4, C1, C2, D1, D3, E1, E2, E3, F1, F2, X and Y chromosome patterns were according to the domestic cat (Felis catus) chromosomes. Chromosomes A2, A3, B1, B2, D2 and D4 are similar to those of the domestic cat. These results show the evolutionary relationship between the leopard and domestic cat. The karyotype formula for the male and female leopard is as follows: 2n(38) = L2m + L4sm + L4a + M2m + M2sm + M4a + S6m + S8sm + S4t + sex chromosomes.

Karyological Study of the Jungle Cat, Felis chaus (Carnivora, Felidae) by Conventional Staining, G-banding and High-resolution Staining Technique

As an endangered species in Thailand, wild animal species of the jungle cat (Felis chaus) was selected for karyological study. Blood samples were taken from 2 males and 2 females. After the standard whole blood lymphocyte culture in the presence of colchicine, the metaphase spreads were performed on microscopic slides and air-dried. Conventional staining, G-banding and high-resolution staining technique were applied to stain the chromosomes. The results showed that 2n (diploid) of jungle cat was 38, and the fundamental number (NF) was 72 in the male and female. There are 6 autosome types: A type had 6 large submetacentric chromosomes, B type had 8 large acrocentric chromosomes, C type had 4 large metacentric chromosomes, D type had 8 small submetacentric chromosomes, E type had 6 small metacentric chromosomes and F type had 4 small telocentric chromosomes. A pair of the short arm of chromosome E1 (chromosome pairs 14) showed a clearly observable satellite chromosomes. The X chromosome was medium submetacentric chromosome and the Y chromosome was the smallest submetacentric chromosome. From the G-banding and high-resolution staining technique, the number of bands and locations in the jungle cat was 167 and 183 respectively, and each chromosome pair could be clearly differentiated. We found that chromosomes B1, B2, D1, D4, E3, F2 and X chromosome patterns were according to the domestic cat (Felis catus) chromosomes. Chromosomes A1, A2, A3, B3, B4, C1, C2, D2, E1, E2, F1 and Y-chromosome are similar to those of the domestic cat. These results show the evolutionary relationship between the jungle cat and domestic cat. The karyotype formula for the male and female jungle cat is as follows: 2n(38) = L4m + L6sm + L8a + S6m + S8sm + S4t + sex chromosomes.

A Study on Karyotype of the Asian Leopard Cat, <i>Prionailurus bengalensis</i> (Carnivora, Felidae) by Conventional Staining, G-banding and High-resolution Technique

A karyotypic study of the Asian leopard cat (Prionailurus bengalensis) in Thailand has been made. Blood samples were taken from 2 males and 2 females. After the standard whole blood lymphocyte culture in the presence of colchicine, the metaphase spreads were performed on microscopic slides and air-dried. Conventional staining, G-banding and high-resolution techniques were applied to stain the chromosomes. The results showed that 2n of the Asian leopard cat was 38, and the fundamental number (NF) was 74 in male and female. There are 6 autosome types: A type has 4 large and 2 medium submetacentric chromosomes, B type has 6 large and 2 medium acrocentric chromosomes, C type has 4 large metacentric chromosomes, D type has 8 small submetacentric chromosomes, E type has 8 small metacentric chromosomes and F type are 2 small telocentric chromosomes. A pair of the short arm of chromosome E1 (chromosome pairs 14) showed a clearly observable satellite chromosomes. The X chromosome was medium submetacentric chromosome and the Y chromosome was the smallest metacentric chromosome. From the G-banding and high-resolution techniques, the number of bands and locations in the Asian leopard cat was 183 and 236 respectively, and each chromosome pair could be clearly differentiated. We found that chromosomes A1, A2, A3, B3, B4, C1, C2, D3, D4, E1, E3, F1 and X chromosome patterns were according to the domestic cat (Felis catus) chromosomes. Chromosomes B1, B2, D2 and E2 are similar to those of the domestic cat. These results show the evolutionary relationship between the Asian leopard cat and the domestic cat. The karyotype formula for the male and female Asian leopard cat is as follows:2n (38)=L4m+L4sm+L6a+M2sm+M2a+S8m+S8sm+St2+Sex-chromosome

A Comparison of the Karyotype of Five Species in Genus Macaca (Primate, Cercopithecidae) in Thailand by Using Conventional Staining, G-banding and High-Resolution Technique

Cytogenetics of 5 macaque species from genus Macaca in Thailand were studied using lymphocyte cultures and high-resolution techniques. Their chromosome numbers are 2n=42, 20 pairs of autosome, and 1 pair of sex-chromosome. M. arctoides and M. mulatta have a fundamental number (NF) 84 in male and female but the others have 83 in male and 84 in female. They have 6 large, 4 medium, 8 small metacentric chromosomes and 8 large, 12 medium, 2 small submetacentric chromosomes respectively. M. fascicularis and M. mulatta have medium metacentric X chromosome. M. assamensis, M. nemestrina and M. arctoides have medium submetacentric X chromosome. M. arctoides has small submetacentric Y chromosomes, M. mulatta has small metacentric Y chromosomes, while M. assamensis, M. fascicularis and M. nemestrina have small telocentric Y chromosomes. By using G-banding in metaphase and high-resolution technique in late prophase, the results show that the bands are 274, 273, 273, 275, 273 and 351, 350, 350, 352, 350 respectively. Their autosome and X chromosome are similar but their Y chromosome is different. The NOR is on the short arm of chromosome 13. The largest is the metacentric chromosome. The smallest is theY chromosome. Thus X and Y chromosomes can use for identification.

Nuclear DNA content and karyotype of Rosewood (Aniba rosaeodora)

Rosewood (Aniba rosaeodora Ducke, Lauraceae) is ecologically and economically important to the Amazon region. As a consequence of its economic importance, rosewood populations have been decimated in the Amazon forest. Species of nine genera of the Lauraceae family have characterized karyotypes with n = x = 12 chromosomes in the gametophytic phase but the genus Aniba is one of the least studied Lauraceae genera with a previously undescribed genome. We used cytogenetic techniques to determine that the A. rosaeodora karyotype contained 12 pairs (2n = 24) of relatively small submetacentric chromosomes with lengths ranging from 1.34 to 2.25 mum and a nucleolar organizer region (NOR) in the short arm of chromosome 7. Flow cytometry gave 2C = 2.32 pg of DNA, equivalent to approximately 2.24 x 10(9) base pairs.

Chromosome Characterization of <i>Astyanax</i> sp B (Characidae, Tetragonopterinae), an Endemic Species of the Iguaçu River, Paraná, Brazil

Cytogenetics studies on Astyanax sp B, an endemic species of the Iguaçu River (Paraná, Brazil) were carried out. The specimens showed a standard diploid number of 2n=50 chromosomes with a karyotype consisting of 6 metacentric, 24 submetacentric, 6 subtelocentric and 14 acrocentric chromosomes. In addition to the basic karyotype, all the specimens presented 1–2 supranumerary or B chromosomes in mitotic metaphases. Three morphological types of B chromosomes have been identified in population under analysis: an acrocentric-type microchromosome; a metacentric macrochromosome smaller than the first pair of the normal karyotype complement; a small submetacentric chromosome. C-band analysis shows discrete markings in the centromeric regions of various chromosomes which contrast with strongly heterochromatic blocks in the telomeric regions of the long arms of chromosome pairs 20, 21 and 22 (acrocentric). Heterochromatic block-sized heteromorphism has been among homologues of pair 20. The chromosome characterisitics of Astyanax sp B indicate similarity with other species of the genus Astyanax with regard to karyotypic macrostructure, distribution of constitutive heterochromatin (C-band pattern) and occurrence of B chromosomes. Some aspects related B chromosomes in this species are discussed.

Karyotype study of Scenedesmus regularis SVIR. and S. pectinatus MEYEN (Chlorophyta, Chlorococcales) in clonal cultures in vitro

The taxonomical status of the species Scenedesmus regularis SVIR. and S. pectinatus MEYEN was discussed by analysis of the karyotype. The results of a morphological and morphometrical chromosomal analysis of Scenedesmus regularis SVIR, and S. pectinatus MEYEN are described in detail. It was found that the karyotype of S. regularis (n = 4) consists of two large submetacentric chromosomes, one small metacentric chromosome and one small submetacentric chromosome. The karyotype of S. pectinatus (n = 5) consists of three large metacentric chromosomes, one small metacentric chromosome and one small submetacentric chromosome. The chromosomes of both species are divided into two groups and three subgroups. The general chromosomal formulae of both species as well as the total average methaphase length of their haploid set were presented. On the basis of the results it was confirmed that S. regularis and S. pectinatus are two separate and actually existing biological species.

On distribution, morphology and biology of the Mole Vole, Ellobius lutescens Thomas, 1897 (Mammalia: Rodentia) in eastern Turkey

Ellobius lutescens reaches the western limit of its distribution in Turkey, and is confined there to a relatively small area in the eastern part of the country near the borders with Iran and Iraq, from where new records are provided (Hakkari: Yüksekova). The species lives in family groups and excavates underground tunnels by scratching the soil with the incisors and pushing the loosened soil behind the body with the fore and hind limbs. Mole Voles are vegetarian and forage in underground burrow systems. They feed primarily on large subterranean edible parts of plants. Both sexes have an apparently identical karyotype (2n = 17, NF = 34). The karyotype consists of 8 pairs of biarmed autosomes and a single small submetacentric chromosome. Both sexes have the chromosome constitution XO. Some biological and morphological peculiarities are discussed.

FISH mapping of the IGF2 gene in horse and donkey-detection of homoeology with HSA11.

Three genomic subclones derived from a phage clone containing the equine IGF2 gene were used to FISH map the gene on horse (ECA) and donkey (EAS) metaphase chromosomes. The gene mapped on ECA 12q13 band and is the first locus mapped to this horse chromosome. In donkey the gene mapped very terminal on the long arm of one small submetacentric chromosome that shows almost identical DAPI-banding pattern with ECA12. This is the first locus mapped in donkey genome. Cross species chromosome painting of equine metaphase chromosomes with human Chromosome (Chr) 11-specific probe showed homoeology of this human chromosome with ECA12 and ECA7. The novel ECA12 comparative painting results are thus in accordance with the localization of the equine IGF2 gene. Comparison of the hitherto known physical locations of IGF2 in different species, viz. human, cattle, sheep, horse, and donkey, shows that this gene tends to maintain a terminal location on the chromosome arm.

Cytogenetics of vesper mice, Calomys (Sigmodontinae): a new karyotype from the Puna region and its implication for chromosomal phylogeny.

The karyotype of specimens identified as Calomys lepidus, trapped at 3600 m above sea level in the Puna region, northwestern Argentina, was studied. All specimens analysed showed a 2n = 44 (NF(a) = 68) asymmetrical karyotype with 13 pairs of metacentric/submetacentric autosomes and 7 pairs of telocentric chromosomes. The X was a medium-sized submetacentric and the Y a small submetacentric chromosome. This karyotype was quite different from that previously described for C. lepidus from Peru (2n = 36, NF(a) = 68). However, both karyotypes may be easily interrelated by means of four centric fusions, and the chromosome complement of Punian C. lepidus fitted into a previously proposed chromosomal phylogeny of the genus. In addition, the spermatozoa of specimens corresponded to a morphological pattern previously described for other species of Calomys.

Supernumerary chromosomes in Nephrops norvegicus L. (Crustacea, Decapoda)

Supernumerary chromosomes have been identified in the chromosome complement of Nephrops norvegicus L. by C-banding and restriction endonuclease-induced banding. These chromosomes showed peculiar features of typical B chromosomes in terms of heterochromatin content, asynapsis and distorted segregation. The presence of these chromosomes can, at least partially, account for the numerical variability already observed in this species; 2n and n values determined by counting these chromosomes separately gave a less variable number of chromosomes in the complement. Q-banding was useful to characterize some large B chromosomes with intercalary and subtelomeric bands as well as entirely positive short arms in some small submetacentric chromosomes. Nucleolar organizer regions have been identified in four pairs of chromosomes by silver staining.