Pairs Of Telocentric Chromosomes Research Articles

Karasu ırmağında (Erzurum) yayılış gösteren Chondrostoma regium'un (Teleostei: Leuciscidae) karyotipik analizleri

In this study, the karyotypic characteristics of Chondrostoma regium (Heckel, 1843) have been investigated. Fish samples were caught from the Karasu River (Euphrates River Basin) with fishing net. The live fish were transported to the laboratory and kept in aerated aquaria before the analyses. The karyotype analysis was performed in fish kidney and gill epithelium cells. It was determined that C. regium had 2n=50 chromosomes. In detail, the karyotype formula of C. regium was determined as 9 metacentric, 7 submetacentric, 1 subtelocentric and 8 telocentric chromosome pairs (18M+14SM+2ST+16T), and fundamental arm number was calculated as 82. Constitutive heterochromatin regions were determined on telomeres of the chromosomes. Nuclear orgnizer regions were detected on 21st chromosome. Karyotype symmetry/asymmetry index was calculated as 2.32. The karyotypes of gill and kidney cells were the same. No sex chromosomes were cytologically detected.

Chromosome Complement of Pomatoschistus marmoratus and Karyotype Evolution in Sand Gobies (Gobiidae: Gobionellinae)

The family Gobiidae constitutes one of the most diverse groups among teleost fish; some of its species are objects of aquaculture and fisheries. Despite many years of cytogenetic studies, the chromosome complements of many species of gobies remain unknown, and the trends of karyotypic evolution are poorly understood. Here I describe a previously unstudied karyotype of a widespread species from the group of sand gobies (Pomatoschistus marmoratus) and analyze the trends of karyotypic evolution of this group in comparison with other taxonomic groups of gobies from the Atlantic-Mediterranean and Ponto-Caspian regions. For P. marmoratus, the diploid number is 2n=46; it consists of 11 pairs of submetacentric chromosomes, 12 pairs of subtelocentric and telocentric chromosomes (NF=68). A comparative karyological analysis showed that the main trend in the karyotypic evolution of sand gobies differs from that of other groups of gobies and is associated with an increase in the number of chromosomal arms as a result of chromosomal rearrangements leading to a change in the centromere position. The results obtained contribute to understanding the role of chromosomal rearrangements in the evolution of Gobiidae and are of interest for further cytogenetic studies of this large family of fish.

Chromosomal description of three Dixonius (Squamata, Gekkonidae) from Thailand

Chromosomal characteristics and karyological analysis of three Dixonius, including D. hangseesom, D. siamensis and D. melanostictus, from Thailand were studied. Chromosome preparations were conducted by squash technique from bone marrow and testis. Conventional Giemsa’s staining and Ag-NOR banding techniques were applied to stain the chromosome. The results showed that the diploid chromosomes are 2n=40, for D. hangseesom and D. siamensis; and 2n=42, for D. melanostictus. The fundamental number (NF) is 42 in D. hangseesom and D. siamensis and 44 in D. melanostictus. The types of chromosomes were 2 metacentrics and 38 telocentrics for D. hangseesom and D. siamensis, while the karyotype of D. melanostictus comprised 2 acrocentrics and 40 telocentrics. In the D. hangseesom and D. siamensis, NORs are located to the near centromere on long arm of the telocentric chromosome pair 13. Although, the NORs of D. melanostictus are situated on the subtelomeric region of telocentric chromosome pair 8. There are no sex differences in karyotypes between males and females of these three geckos species. We found that during metaphase I and metaphase II on male meiosis of the D. hangseesom and D. siamensis, the homologous chromosomes showed synapsis of 20 bivalents and 20 haploid chromosomes (n=20). Moreover, metaphase I and metaphase II of the male D. melanostictus showed synapsis of 21 bivalents and 21 haploid chromosomes (n=21). Their karyotype formulas is as follows: D. hangseesom (2n=40): Lm2 + Lt2 + Mt4 + St32, D. siamensis (2n=40): Lm2 + Lt6 + Mt4 + St28, and D. melanostictus (2n=42): La2 + Lt12 + Mt4 + St24.

First karyotype description of the species of Adenomera Steindachner, 1867 (Anura, Leptodactylidae) in the " thomei" clade.

The genus Adenomera Steindachner, 1867 currently comprises 29 nominal species, some of which are suggested to be cryptic species complexes. The present study was carried out with specimens of the "thomei" clade that encompasses three taxa distributed in the Atlantic Forest biome: Adenomerathomei Almeida et Angulo, 2006, Adenomera sp. L., and Adenomera sp. M. We used classical cytogenetics to describe the diploid number and karyomorphology of these three species collected in two different locations in the state of Bahia, Brazil. Our results revealed the diploid number 2n = 24 (FN = 34) with two pairs of metacentric chromosomes (pairs 1 and 5), three pairs of submetacentric chromosomes (pairs 2, 3, and 4), and seven pairs of telocentric chromosomes (pairs 6, 7, 8, 9, 10, 11, and 12). Further morphological, bioacoustic, and cytogenetic data (C-banding and AgNor) are needed to better delineate the lineages within the "thomei" clade.

FISH Identifies Chromosome Differentiation Between Contemporary Genomes of Wild Types and the Ancestral Genome of Unisexual Clones of Dojo Loach, Misgurnus anguillicaudatus

In dojo loach (Misgurnus anguillicaudatus), although most wild types are gonochoristic diploids that are genetically differentiated into 2 groups, A and B, clonal lineages appear in certain localities. Clonal loaches have been considered to have hybrid origins between the 2 groups by a series of genetic studies. In this study, using FISH with a newly developed probe (ManDra-A), we identified 26 (1 pair of metacentric and 12 pairs of telocentric chromosomes) of 50 diploid chromosomes in contemporary wild-type group A loach. In contrast, ManDra-A signals were not detected on metacentric chromosomes derived from the ancestral group A of clonal loach. The FISH results clearly showed the presence of certain differentiations in metacentric chromosomes between ancestral and contemporary group A loach. Two-color FISH with ManDra-A and group B-specific ManDra (renamed ManDra-B) probes reconfirmed the hybrid origin of clones by identifying chromosomes from both groups A and B in metaphases. Our results showed the hybrid origin of clonally reproducing fish and the possibility that chromosomal differentiation between ancestral and contemporary fish can affect gametogenesis. In meiotic spermatocytes of sex-reversed clones, ManDra-A, and not ManDra-B, signals were detected in 12 out of 50 bivalents. Thus, the results further support the previous conclusion that clonal gametogenesis was assured by pairing between sister chromosomes duplicated from each ancestral chromosome from group A or B. Our study deepens the knowledge about the association between clonality and hybridity in unisexual vertebrates.

The First Karyological Analysis of the Sixbar Grouper Epinephelus sexfasciatus (Valenciennes, 1828) (Perciformes, Epinephelinae)

This study examines for the first time of karyotypic analysis and chromosomal characteristic of nucleolar organizer regions/NORs of Epinephelus sexfasciatus. The fish samples were collected from Andaman Sea, Phuket province, southern Thailand. The chromosomes were investigated using conventional Giemsa’s staining and Ag-NORs banding techniques. Fish chromosome preparations were conducted by squash technique from kidney. The results showed that the diploid chromosome number of E. sexfasciatus was 2n=48 and the fundamental number (NF, number of chromosome arms) was 48. The type of chromosomes included 24 large telocentric and 24 medium telocentric chromosomes. After Ag-NOR banding technique, single pair of NORs was observed on the short arm of medium telocentric chromosome pair 23. The idiogram shows gradually decreasing length of the chromosomes. A size difference of the largest and the smallest chromosomes is approximately two folds. The karyotype formula could be infered as: 2n(48) = 2n(48)= Lt24+Mt24.

Cytogenetic Characterization of Three Arabian Gulf Bivalve Species

The diploid number and karyotype of three endemic and highly distributed species from the Qatari shores: Brachidontes variabilis (Krauss, 1848) (Mytilidae), Isognomon nucleus (Lamarck, 1819) (Pteriidae) and Neotrapezium sublaevigatum (Lamarck, 1819) (Trapezidae), are described for the first time. Brachidontes variabilis presented a diploid number of 2n = 30 and the karyotype included 2 metacentric, 6 submetacentric, 3 subtelocentric and 4 telocentric chromosome pairs. Isognomon nucleus had a diploid number 2n = 28 and the karyotype was comprised of 3 metacentric, 4 submetacentric and 7 subtelocentric chromosomal pairs and the karyotype of Neotrapezium sublaevigatum, with 2n = 36, included 5 metacentric, 9 submetacentric, 2 submetacentric/subtelocentric and 2 subtelocentric chromosome pairs. A review of the previously published cytogenetic studies in all three families was also performed, as well as a comparative karyological analysis within those families.

Chromosomal Metaphase Spreads with G and NOR bandings of Fresh Water Teleost, Clarias batrachus

Background,The detail structure of chromosomes depicted by their banding pattern is very useful in drawing homology and analogy in the structure of chromosome within and between the species. Results, In the present study, the diploid number of chromosomes was 50 in the fresh water teleost, Clarias batrachus in which 18 metacentric, 20 submetacentric and 12 telocentric chromosomes were observed. Structurally, the G bands revealed that transverse bands were visible after banding. These were due to the presence of heterochromatin and presence and absence of bases, these bands were observed at two pairs of submetacentric chromosomes. The NOR bands on the chromosomes were detected by silver staining in the two pairs of medium size telocentric chromosomes. It was believed that silver staining bound with the non-histone proteins of the transcriptionally active NOR region. Conclusion, Our results showed that basic information of chromosome number and morphology with G and NOR banding can be used as an important tool for cytogenetic data of fresh water teleost Clarias batrachus.

Molecular Cytogenetic Analysis and Meiotic Pairing Behavior of Progenies Originating from a Hexaploid Triticale (×Triticosecale, Wittmack) and Bread Wheat (Triticum aestivum, L.) Cross

The chromosomal constitution of 9 dwarf (D) and 8 semidwarf (SD) lines derived by crossing hexaploid Triticale line NA-75 (AABBRR, 2n = 6x = 42) with Triticumaestivum (AABBDD, 2n = 6x = 42) cv. Chinese Spring was investigated using molecular cytogenetic techniques: fluorescence in situ hybridization and genomic in situ hybridization. A wheat-rye translocation (T4DS.7RL), 8 substitution lines, and a ditelosomic addition line (7RSdt) were identified. In the substitution lines, 1, 2, or 4 pairs of wheat chromosomes, belonging to the A, B, or D genome, were replaced by rye chromosomes. Substitutions between chromosomes belonging to different wheat genomes [5B(5A), 1D(1B)] also occurred. The lines were genetically stable, each carrying 42 chromosomes, except the wheat-rye ditelosomic addition line, which carried 21 pairs of wheat chromosomes and 1 pair of rye telocentric chromosomes (7RS). The chromosome pairing behavior of the lines was studied during metaphase I of meiosis. The chromosome pairing level and the number of ring bivalents were different for each line. Besides rod bivalents, univalent and multivalent associations (tri- and quadrivalents) were also detected. The main goal of the experiment was to develop genetically stable wheat/Triticale recombinant lines carrying chromosomes/chromatin fragments originating from the R genome of Triticale line NA-75. Introgression of rye genes into hexaploid wheat can broaden its genetic diversity, and the newly developed lines can be used in wheat breeding programs.

Description of the karyotype of Sphyracephala detrahens (Diptera, Diopsidae).

The eye stalks in Diopsidae (Bilberg, 1820) have been widely examined, but the evolutionary origin of this unique trait remains unclear. Thus, further studies of Sphiracephala (Say, 1828), the extant genus forming a basal branch of Diopsinae, are needed. The present study aimed to identify the karyotype of Sphyracephala detrahens (Walker, 1860) with conventional Giemsa staining. Cytogenetic analysis revealed a diploid number of 2n = 10 including two pairs of metacentric chromosomes, a pair of telocentric chromosomes, a pair of dot-like chromosomes, and a pair of sex chromosomes in S. detrahens. The congener Sphyracephala brevicornis (Say, 1817) has been reported to have the same diploid number, 2n = 10, but different chromosome formula. These results demonstrate that chromosome rearrangements often occur in the genus Sphyracephala.

Cytogenetics of Eudiplozoon nipponicum (Monogenea, Diplozoidae): Karyotype, spermatocyte division and 18S rDNA location

Ectoparasitic monogeneans of the family Diplozoidae have direct and monoxenous life cycle. The cytogenetics of monogeneans in general and diplozoids in particular, is a relatively underexplored area. This is why each new detailed description of a karyotype provides significant information about the evolution of monogenean chromosomes and contributes to a better understanding of phylogenetic relationships within this group. This study offers new data on the chromosomes of Eudiplozoon nipponicum, an invasive parasite of the common carp. This species' karyotype consists of seven pairs of telocentric chromosomes (2n = 14 t). After DAPI staining, we marked heterochromatin blocks on all chromosomes in the pericentromeric region. Silver staining (AgNO3) and staining with fluorescent dye YOYO-1 revealed the presence of one large active nucleolus. Fluorescent in situ hybridization with an 18S rDNA probe revealed one cluster of ribosomal genes at the terminal part of the long arms of chromosome pair No. 7. We compared our results with studies on the phylogenetic relationships of diplozoids which applied a combination of molecular methods and classical morphological characterization and found that the results of our cytogenetic analysis are consistent with the hypothesis that E. nipponicum is more basal member of the family Diplozoidae.

Chromosomal study of Khawia abbottinae (Cestoda: Caryophyllidea): karyotype and localization of telomeric and ribosomal sequences after fluorescence in situ hybridization (FISH).

An original cytogenetic study combining classical karyotype analysis and modern fluorescence in situ hybridization using telomeric (TTAGGG)n and ribosomal sequences (18S rDNA) was performed in Khawia abbottinae (Cestoda, Caryophyllidea), a parasite of Chinese false gudgeon (Abbottina rivularis) from China. Analyses based on conventional Giemsa staining, DAPI, YOYO-1 dye, and silver (Ag) staining were also carried out. The karyotype is composed of eight pairs of metacentric and telocentric chromosomes (2n = 16, n=5m + 3t). Constitutive heterochromatin was mainly positioned at pericentromeric regions, and telomeric sequences (TTAGGG)n were restricted to the end of all chromosomes. In mitotic preparations stained with Giemsa, both homologues of chromosome pair 4 showed a distinct secondary constriction. FISH with rDNA probe confirmed that this secondary constriction contains a nucleolar organizer region (NOR). The process of spermatocyte meiosis and the dynamics of nucleolus degradation in dividing cell were scrutinized. The present study and its results enhance the limited knowledge on basic karyotype characteristics and 18S rDNA clusters location in caryophyllidean tapeworms.

Chromosome studies on freshwater prawn, Macrobrachium lanchesteri (Decapoda, Palaemonidae) from Thailand

The chromosomes of freshwater prawn (Macrobrachium lanchesteri) were characterized by means of conventional Giemsa-, DAPI-, silver-staining and G-banding techniques. The number of diploid chromosome and fundamental number were 2n = 116 and 226, respectively. The karyotype consisted of 54 metacentric, 46 submetacentric, 10 acrocentric and 6 telocentric chromosome pairs. The karyotype formula could be deduced as 2n (116) = L 24 m + L 8 a + M 12 m + M 6 sm + M 2 a + S 18 m + S 40 sm + S 6 t . Heterochromatic regions were located in the centromere and pericentromeric regions of most chromosomes, and NORs were found on two pairs of small chromosomes. G-band karyotype of M. lanchesteri was provided for the first time.

Compensation Ability between the Chromosomes of Homoeologous Group 7 of Triticum aestivum L. and Hordeum marinum ssp. gussoneanum Hudson (2n = 28) and Analysis of the Transmission Frequency of Alien 7H1Lmar Chromosome through Gametes in the Progeny of Wheat–Barley Substitution Lines

On the basis of directed chromosome substitution, ditelosomic (DT) wheat–barley substitution lines (2n = 42 = 40 + 2t) with participation of wild tetraploid barley Hordeum marinum ssp. gussoneanum Hudson (2n = 28) were first obtained and analyzed. GISH analysis of the substitution lines showed that they carried a pair of telocentric barley chromosomes. With the help of ditelosomic analysis, the lines were identified as DT7HILmar(7A) and DT7HILmar(7B). On the basis of the compensation test and the study of meiotic stability of substitution lines, it was demonstrated that 7HILmar chromosome of H. marinum was homoeologous to the group 7 chromosomes of common wheat. Analysis of the gamete transfer frequency in the progeny of reciprocal hybrids between F1 7A-7HILmar, 7B-7HILmar, 7D-7HILmar and Saratovskaya 29 cultivar showed that the gamete with alien chromosome n = 20 + t successfully competed with euploid gamete n = 21 in both macrosporogenesis and microsporogenesis.

Chromosome evolution in Cophomantini (Amphibia, Anura, Hylinae).

The hylid tribe Cophomantini is a diverse clade of Neotropical treefrogs composed of the genera Aplastodiscus, Boana, Bokermannohyla, Hyloscirtus, and Myersiohyla. The phylogenetic relationships of Cophomantini have been comprehensively reviewed in the literature, providing a suitable framework for the study of chromosome evolution. Employing different banding techniques, we studied the chromosomes of 25 species of Boana and 3 of Hyloscirtus; thus providing, for the first time, data for Hyloscirtus and for 15 species of Boana. Most species showed karyotypes with 2n = 2x = 24 chromosomes; some species of the B. albopunctata group have 2n = 2x = 22, and H. alytolylax has 2n = 2x = 20. Karyotypes are all bi-armed in most species presented, with the exception of H. larinopygion (FN = 46) and H. alytolylax (FN = 38), with karyotypes that have a single pair of small telocentric chromosomes. In most species of Boana, NORs are observed in a single pair of chromosomes, mostly in the small chromosomes, although in some species of the B. albopunctata, B. pulchella, and B. semilineata groups, this marker occurs on the larger pairs 8, 1, and 7, respectively. In Hyloscirtus, NOR position differs in the three studied species: H. alytolylax (4p), H. palmeri (4q), and H. larinopygion (1p). Heterochromatin is a variable marker that could provide valuable evidence, but it would be necesserary to understand the molecular composition of the C-bands that are observed in different species in order to test its putative homology. In H. alytolylax, a centromeric DAPI+ band was observed on one homologue of chromosome pair 2. The band was present in males but absent in females, providing evidence for an XX/XY sex determining system in this species. We review and discuss the importance of the different chromosome markers (NOR position, C-bands, and DAPI/CMA3 patterns) for their impact on the taxonomy and karyotype evolution in Cophomantini.

Karyotypic study of five Lutjanid species using conventional and Ag-NORs banding techniques

The first cytogenetic comparisons of five snapper species from Thailand were presented here. Renal cell samples were taken from blacktail snapper (Lutjanus fulvus), five lined snapper (L. quinquelineatus), dory snapper (L. fulviflamma), brownstripe red snapper (L. vitta), and mangrove red snapper (L. argentimaculatus). The mitotic chromosome preparation was prepared directly from kidney cells. Conventional staining and Ag-NOR banding techniques were applied to stain the chromosomes. The results exhibited that all five snapper species have the diploid chromosome numbers of 2n = 48 and the fundamental numbers (NF) of 48. The presences of large, medium, and small telocentric chromosomes were 22-24-2, 24-20-4, 36-10-2, 28-16-4 and 36-10-2, respectively. The Ag- NORs banding technique provides the pair of nucleolar organizer regions (NORs) at subcentromeric region of the long arm of the respective telocentric chromosome pairs 9, 1, 3, 4 and 9. Their karyotype formulas is as follows: L. fulvus (2n = 48): L 22 t + M 24 t + S 2 t , L. quinquelineatus (2n = 48): L 24 t + M 20 t + S 4 t , L. fulviflamma (2n = 48): Lt36 + Mt10 + St2, L. vitta (2n = 48): L 28 t + M 16 t + S 4 t , and L. argentimaculatus (2n = 48): L 36 t + M 10 t + S 2 t .

Comparative cytogenetics of tree frogs of the Dendropsophus marmoratus (Laurenti, 1768) group: conserved karyotypes and interstitial telomeric sequences.

The diploid number 2n = 30 is a presumed synapomorphy of Dendropsophus Fitzinger, 1843, although a noticeable variation in the number of biarmed/telocentric chromosomes is observed in this genus. Such a variation suggests that several chromosomal rearrangements took place after the evolutionary origin of the hypothetical ancestral 30-chromosome karyotype; however, the inferred rearrangements remain unknown. Distinct numbers of telocentric chromosomes are found in the two most cytogenetically studied species groups of Dendropsophus. In contrast, all three species of the Dendropsophus marmoratus (Laurenti, 1768) group that are already karyotyped presented five pairs of telocentric chromosomes. In this study, we analyzed cytogenetically three additional species of this group to investigate if the number of telocentric chromosomes in this group is not as variable as in other Dendropsophus groups. We described the karyotypes of Dendropsophus seniculus (Cope, 1868), Dendropsophus soaresi (Caramaschi & Jim, 1983) and Dendropsophus novaisi (Bokermann, 1968) based on Giemsa staining, C-banding, silver impregnation and in situ hybridization with telomeric probes. Dendropsophus seniculus, Dendropsophus soaresi and Dendropsophus novaisi presented five pairs of telocentric chromosomes, as did the remaining species of the group previously karyotyped. Though the species of this group show a high degree of karyotypic similarity, Dendropsophus soaresi was unique in presenting large blocks of het-ITSs (heterochromatic internal telomeric sequences) in the majority of the centromeres. Although the ITSs have been interpreted as evidence of ancestral chromosomal fusions and inversions, the het-ITSs detected in the karyotype of Dendropsophus soaresi could not be explained as direct remnants of ancestral chromosomal rearrangements because no evidence of chromosomal changes emerged from the comparison of the karyotypes of all of the species of the Dendropsophus marmoratus group.

Karyological analysis of Korean endemic land snail,Koreanohadra kurodana(Gastropoda: Bradybaenidae)

AbstractThe karyotypes of the Korean endemic land snail, Koreanohadra kurodana, were investigated using the air-drying method. The diploid chromosome number for this species was 2n = 58, including 23 metacentric chromosome pairs, five submetacentric chromosome pairs and one telocentric chromosome pair; therefore, the fundamental number was FN = 56. Observed chromosomes ranged from 2.1 to 8.5% in total length and the mean total length of the chromosomes in the diploid was 95.5 ± 1.34 μm.

Karyological characteristics of the Koh Tao caecilian, Ichthyophis kohtaoensis (Amphibia: Gymnophiona: Ichthyophiidae) by conventional staining and Ag-NOR banding techniques

The karyotypic analysis of the Koh Tao caecilian, Ichthyophis kohtaoensis Taylor, on 1960 from Surin Province, Thailand was obtained from the present study. Mitotic chromosome was prepared directly from the small intestine of specimens after in vivo colchicine treatment. The metaphase spreads were performed on microscopic slides and air-dried. Conventional staining, and Ag-NOR banding techniques were applied to stain the chromosome with Giemsa’s solution. Results showed that the number of diploid chromosome was 2n = 42, while the fundamental number (NF) was 64 in both males and females. The type of chromosomes included 6 large metacentric, 2 large submetacentric, 12 small metacentric, 2 small submetacentric, and 20 small telocentric chromosomes. We found that nucleolar organizer regions/NORs (the representative of chromosome marker) were located on the small telocentric chromosome pair 19. No cytologically distinguishable sex chromosome was observed. The karyotype formula is as follows: 2n (42) = L 6 m + L 2 sm + S 12 m + S 2 sm + S 20 t .

Chromosomal mapping of tandem repeats in the Yesso Scallop, Patinopecten yessoensis (Jay, 1857), utilizing fluorescence in situ hybridization.

Construction of cytogenetic maps can provide important information for chromosome identification, chromosome evolution and genomic research. However, it hasn’t been conducted in many scallop species yet. In the present study, we attempted to map 12 fosmid clones containing tandem repeats by fluorescence in situ hybridization (FISH) in the Yesso scallop Patinopecten yessoensis (Jay, 1857). The results showed 6 fosmid clones were successfully mapped and distributed in 6 different pairs of chromosomes. Three clones were respectively assigned to a pair of metacentric chromosomes, a pair of submetacentric chromosomes and a pair of telocentric chromosomes and the remaining 3 clones showed their loci on three different pairs of subtelocentric chromosomes by co-hybridization. In summary, totally 8 pairs of chromosomes of the Yesso scallop were identified by 6 fosmid clones and two rDNA probes. Furthermore, 6 tandem repeats of 5 clones were sequenced and could be developed as chromosome specific markers for the Yesso scallop. The successful localization of fosmid clones will undoubtedly facilitate the integration of linkage groups with cytogenetic map and genomic research for the Yesso scallop.