Pairs Of Telocentric Chromosomes Research Articles

Karyotype analysis and ribosomal gene localization of spotted knifejaw Oplegnathus punctatus.

The spotted knifejaw, Oplegnathus punctatus, is an important aquaculture fish species in China. To better understand the chromosomal microstructure and the karyotypic origin of this species, cytogenetic analysis was performed using Giemsa staining to identify metaphase chromosomes, C-banding to detect C-positive heterochromatin, silver staining to identify the nucleolus organizer regions (Ag-NORs), and fluorescence in situ hybridization (FISH) for physical mapping of the major (18S rDNA) and minor (5S rDNA) ribosomal genes. The species showed a karyotype of 2n = 48 for females, composed of 2 submetacentric and 46 telocentric chromosomes, with a fundamental number (FN) = 50, while the karyotype of males was 2n = 47, composed of 1 exclusive large metacentric, 2 submetacentric, and 44 telocentric chromosomes, with FN = 50. These karyotype results suggest that O. punctatus might have an X1X1X2X2/X1X2Y multiple sex chromosome system. C-positive heterochromatin was distributed in the centromeres of all chromosomal pairs and in the terminal portions of some chromosomes. A single pair of Ag-positive NORs was found to be localized at the terminal regions of the short arms of the subtelocentric chromosome pair, which was supported by FISH of 18S rDNA. After FISH, 5S rDNA were located on the interstitial regions of the smallest telocentric chromosome pair. This study was the first to identify the karyotype of this species and will facilitate further research on karyotype evolution in the order Perciformes.

Cytotaxonomy of unionid freshwater mussels (Unionoida, Unionidae) from northeastern Thailand with description of a new species.

Morphological and chromosomal characteristics of a number of unionid freshwater mussels were studied from northeastern Thailand. Karyotypes of eight species from seven genera (Chamberlainia, Ensidens, Hyriopsis, Physunio, Pseudodon, Scabies and Trapezoideus) were examined. Six species possess 2n = 38 karyotypes, whereas Scabies crispata and an unidentified Scabies sp. lack three small chromosome pairs, giving a diploid number of 32. Moreover, the karyotypes of the unidentified Scabies differ from Scabies crispata as it exhibits a telocentric chromosome pair (6m + 7sm + 2st + 1t). Most of the conchological characters also differ between the two species – adult size, colour pattern, muscle scars, pseudocardinal and lateral teeth. The name Scabies songkramensis sp. n. is proposed for the unidentified species, and its description is included in this paper. Interestingly, seven species contain mostly bi-armed chromosomes, but only the mud-dweller in stagnant water, Ensidens ingallsianus, contains predominantly five telocentric pairs. In addition, the marker chromosome characteristics of an unbalanced long arm, twisted centromere, a wider angle 180° arrangement, a twisted arm and telomeric end union reported in this study are described for the first time for unionid mussels.

Next-Generation Survey Sequencing and the Molecular Organization of Wheat Chromosome 6B

Common wheat (Triticum aestivum L.) is one of the most important cereals in the world. To improve wheat quality and productivity, the genomic sequence of wheat must be determined. The large genome size (∼17 Gb/1 C) and the hexaploid status of wheat have hampered the genome sequencing of wheat. However, flow sorting of individual chromosomes has allowed us to purify and separately shotgun-sequence a pair of telocentric chromosomes. Here, we describe a result from the survey sequencing of wheat chromosome 6B (914 Mb/1 C) using massively parallel 454 pyrosequencing. From the 4.94 and 5.51 Gb shotgun sequence data from the two chromosome arms of 6BS and 6BL, 235 and 273 Mb sequences were assembled to cover ∼55.6 and 54.9% of the total genomic regions, respectively. Repetitive sequences composed 77 and 86% of the assembled sequences on 6BS and 6BL, respectively. Within the assembled sequences, we predicted a total of 4798 non-repetitive gene loci with the evidence of expression from the wheat transcriptome data. The numbers and chromosomal distribution patterns of the genes for tRNAs and microRNAs in wheat 6B were investigated, and the results suggested a significant involvement of DNA transposon diffusion in the evolution of these non-protein-coding RNA genes. A comparative analysis of the genomic sequences of wheat 6B and monocot plants clearly indicated the evolutionary conservation of gene contents.

Cytogenetic characterisation of the Caspian Pond Turtle, Mauremys caspica in Golestan and Mazandaran provinces, Iran (Reptilia: Testudines)

Cytogenetic characteristics of the Caspian Pond Turtle, Mauremys caspica, in Golestan and Mazandaran provinces in the northern part of Iran show that the chromosome number is 2n = 52 and the arm number NF = 78. The karyotype consisted of 9 metacentric (M), 1 submetacentric (SM), 3 subtelocentric (ST) and 13 telocentric (T) chromosome pairs. The Centromeric Index ranges from 11.79 to 45.68, the arm ratio between 1.18 and 7.47, the relative length between 1.60 and 11.46, and the length variation between 1.05 and 7.48. Average total length of the chromosomes is 65.27 µm. The largest chromosome in this species is a pair of the metacentric chromosome. Location of NOR was determined on chromosome pair no. 10.

Karyological analysis of the shrimp Palaemon serratus (Decapoda: Palaemonidae)

Analysis of metaphases of Palaemon serratus (Pennant, 1777) revealed a diploid number of 2n=56 chromosomes with a karyotype composed of two large metacentric pairs, six subtelocentric pairs and twenty telocentric pairs. Four Ag-NORs and 45S rDNA signals were observed at the telomeres of two small telocentric chromosome pairs. Chromomycin A3 fluorochrome staining revealed GC-rich regions associated with Ag-NORs, and DAPI showed positive bright bands on centromeric or intercalary positions of subtelocentric and telocentric chromosomes.

Chromosomes of Lepidochitona caprearum (Scacchi, 1836) (Polyplacophora, Acanthochitonina, Tonicellidae) provide insights into Acanthochitonina karyological evolution

We describe the karyotype, location of nucleolus-organizing regions (NORs) and heterochromatin composition and distribution in Lepidochitona caprearum (Scacchi, 1836). The examined specimens had 2n=24 chromosomes; the elements of pairs 1–4 were metacentric, subtelocentric those of the fifth pair, telocentric the elements of other pairs. NOR-FISH, Ag-NOR- and CMA3 banding showed NORs localized on pericentromeric regions of a medium small sized, telocentric chromosome pair. After C-banding or digestions with restriction enzyme NOR associate heterochromatin only was cytologically evident, resulting CMA3 positive. The comparison with chromosome data of other chitons, other than to evidence a karyotypic similarity of Lepidochitona caprearum to species of suborder Acanthochitonina, allows us to infer that chromosome evolution in the suborder mainly occurred via reduction of the number of the chromosomes by centric fusions, which took place repeatedly and independently in the different lineages of Acanthochitonina.

Cytogenetic characterisation of the razor shells Ensis directus (Conrad, 1843) and E. minor (Chenu, 1843) (Mollusca: Bivalvia)

The European razor shell Ensis minor (Chenu 1843) and the American E. directus (Conrad 1843) have a diploid chromosome number of 38 and remarkable differences in their karyotypes: E. minor has four metacentric, one metacentric–submetacentric, five submetacentric, one subtelocentric and eight telocentric chromosome pairs, whereas E. directus has three metacentric, two metacentric–submetacentric, six submetacentric, six subtelocentric and two telocentric pairs. Fluorescent in situ hybridisation (FISH) using a major ribosomal DNA probe located the major ribosomal genes on one submetacentric chromosome pair in both species; FISH with a 5S ribosomal DNA (5S rDNA) probe rendered one chromosomal (weak) signal for E. minor and no signal for E. directus, supporting a more dispersed organisation of 5S rDNA compared to the major ribosomal genes. The vertebrate telomeric sequence (TTAGGG) n was located on both ends of each chromosome, and no interstitial signals were detected. In this work, a comparative karyological analysis was also performed between the four Ensis species analysed revealing that the three European species studied so far, namely E. minor, E. siliqua (Linne 1758) and E. magnus Schumacher 1817 show more similarities among them than compared to the American species E. directus. In addition, clear karyotype differences were found between the morphologically similar species E. minor and E. siliqua.

Cytogenetic analyses of eight species in the genus Leptodactylus Fitzinger, 1843 (Amphibia, Anura, Leptodactylidae), including a new diploid number and a karyotype with multiple translocations

BackgroundThe karyotypes of Leptodactylus species usually consist of 22 bi-armed chromosomes, but morphological variations in some chromosomes and even differences in the 2n have been reported. To better understand the mechanisms responsible for these differences, eight species were analysed using classical and molecular cytogenetic techniques, including replication banding with BrdU incorporation.ResultsDistinct chromosome numbers were found: 2n = 22 in Leptodactylus chaquensis, L. labyrinthicus, L. pentadactylus, L. petersii, L. podicipinus, and L. rhodomystax; 2n = 20 in Leptodactylus sp. (aff. podicipinus); and 2n = 24 in L. marmoratus. Among the species with 2n = 22, only three had the same basic karyotype. Leptodactylus pentadactylus presented multiple translocations, L. petersii displayed chromosome morphological discrepancy, and L. podicipinus had four pairs of telocentric chromosomes. Replication banding was crucial for characterising this variability and for explaining the reduced 2n in Leptodactylus sp. (aff. podicipinus). Leptodactylus marmoratus had few chromosomes with a similar banding patterns to the 2n = 22 karyotypes. The majority of the species presented a single NOR-bearing pair, which was confirmed using Ag-impregnation and FISH with an rDNA probe. In general, the NOR-bearing chromosomes corresponded to chromosome 8, but NORs were found on chromosome 3 or 4 in some species. Leptodactylus marmoratus had NORs on chromosome pairs 6 and 8. The data from C-banding, fluorochrome staining, and FISH using the telomeric probe helped in characterising the repetitive sequences. Even though hybridisation did occur on the chromosome ends, telomere-like repetitive sequences outside of the telomere region were identified. Metaphase I cells from L. pentadactylus confirmed its complex karyotype constitution because 12 chromosomes appeared as ring-shaped chain in addition to five bivalents.ConclusionsSpecies of Leptodactylus exhibited both major and minor karyotypic differences which were identified by classical and molecular cytogenetic techniques. Replication banding, which is a unique procedure that has been used to obtain longitudinal multiple band patterns in amphibian chromosomes, allowed us to outline the general mechanisms responsible for these karyotype differences. The findings also suggested that L. marmoratus, which was formerly included in the genus Adenomera, may have undergone great chromosomal repatterning.

Cytogenetic characterization and genome size of the medicinal plant Catharanthus roseus (L.) G. Don.

Catharanthus roseus is a highly valuable medicinal plant producing several terpenoid indole alkaloids (TIAs) with pharmaceutical applications, including the anticancer agents vinblastine and vincristine. Due to the interest in its TIAs, C. roseus is one of the most extensively studied medicinal plants and has become a model species for the study of plant secondary metabolism. However, very little is known about the cytogenetics and genome size of this species, in spite of their importance for breeding programmes, TIA genetics and emerging genomic research. Therefore, the present paper provides a karyotype description and fluorescence in situ hybridization (FISH) data for C. roseus, as well as a rigorous characterization of its genome size. The organization of C. roseus chromosomes was characterized using several DNA/chromatin staining techniques and FISH of rDNA. Genome size was investigated by flow cytometry using an optimized methodology. The C. roseus full chromosome complement of 2n = 16 includes two metacentric, four subtelocentric and two telocentric chromosome pairs, with the presence of a single nucleolus organizer region in chromosome 6. An easy and reliable flow cytometry protocol for nuclear genome analysis of C. roseus was optimized, and the C-value of this species was estimated to be 1C = 0.76 pg, corresponding to 738 Mbp. The organization and size of the C. roseus genome were characterized, providing an important basis for future studies of this important medicinal species, including further cytogenetic mapping, genomics, TIA genetics and breeding programmes.

Classical and molecular cytogenetics of Khawia sinensis (Cestoda: Caryophyllidea), invasive parasite of carp, Cyprinus carpio

Chromosomes of the invasive tapeworm Khawia sinensis (Caryophyllidea), the specific parasite of common carp, were analyzed by means of conventional Giemsa staining and using fluorescent DAPI and YOYO-1 dyes, silver staining, and fluorescent in situ hybridization (FISH) with 18S rDNA probe. The karyotype is composed of eight pairs of metacentric and telocentric chromosomes (2n = 16, n = 3m + 5t, TCL = 42.54 μm). Constitutive heterochromatin was located at pericentromeric regions of all pairs, except for the largest metacentric pair (no. 1), which possessed no DAPI-positive band. FISH with rDNA probe revealed that both homologues of chromosome pair no. 6 carry a cluster of ribosomal arrays, which were located interstitially close to the centromere. Present results are compared with previous cytogenetic data on Khawia spp., and comments are made on the karyotypes with respect to their phylogenetic links.

Next‐generation sequencing and syntenic integration of flow‐sorted arms of wheat chromosome 4A exposes the chromosome structure and gene content

Wheat is the third most important crop for human nutrition in the world. The availability of high-resolution genetic and physical maps and ultimately a complete genome sequence holds great promise for breeding improved varieties to cope with increasing food demand under the conditions of changing global climate. However, the large size of the bread wheat (Triticum aestivum) genome (approximately 17 Gb/1C) and the triplication of genic sequence resulting from its hexaploid status have impeded genome sequencing of this important crop species. Here we describe the use of mitotic chromosome flow sorting to separately purify and then shotgun-sequence a pair of telocentric chromosomes that together form chromosome 4A (856 Mb/1C) of wheat. The isolation of this much reduced template and the consequent avoidance of the problem of sequence duplication, in conjunction with synteny-based comparisons with other grass genomes, have facilitated construction of an ordered gene map of chromosome 4A, embracing ≥85% of its total gene content, and have enabled precise localization of the various translocation and inversion breakpoints on chromosome 4A that differentiate it from its progenitor chromosome in the A genome diploid donor. The gene map of chromosome 4A, together with the emerging sequences of homoeologous wheat chromosome groups 4, 5 and 7, represent unique resources that will allow us to obtain new insights into the evolutionary dynamics between homoeologous chromosomes and syntenic chromosomal regions.

A karyological analysis of Puntius conchonius (Hamilton, 1822) (Pisces, Cyprinidae), a new cytotype from Dal Lake Srinagar Kashmir, JK, India

The karyotypic and cytological characteristics of Rosy barb, Puntius conchonius (Hamilton, 1822) (cyprinidae) were investigated by examining metaphase chromosomes spreads from the anterior kidney following Thorgaard and Disney (1990). The fishes were obtained from the local fishermen and transported live to the Limnology and Fisheries Laboratory of Centre of Research for Development, University of Kashmir. Ten fish were injected intraperitoneally with two doses of phytohemagglutinin (PHA), 4 µg g-1body weight with a 20 h interval to induce cell division. After 8 h in 20°C water, the fish were injected intraperitoneally with colchicine 0.05% @ 0.5 ml/50 g body weight to depress the cell division in the metaphase stage and left for 2 to 3 h before sacrificing. Kidney and gill epithelia were used for karyotype analysis. The diploid chromosome number of the fish was 2n = 50, consisting of 11 pairs of metacentric, 8 pairs of submetacentric and 6 pairs of telocentric chromosomes respectively. Centromeric index, arm ratio and Fundamental Number were determined as 0 to 50, 1-∞ and 88 respectively. No heteromorphic sex chromosomes were cytologically detected. Key words: Chromosome, Puntius conchonius, Dal Lake, karyotype.

Possible genetic reproductive isolation between two tilapiine genera and species: Oreochromis niloticus and Sarotherodon melanotheron.

Successful crossbreeding between Oreochromis niloticus and Sarotherodon melanotheron to produce a commercial hybrid has been difficult. The karyotypes and isoenzyme of these two species and their reciprocal hybrids (O. niloticus female × S. melanotheron male, S. melanotheron female × O. niloticus male, the last not included in the isoenzyme study) were investigated via metaphase chromosomes obtained from head kidney cells and electropherogram of lactate dehydrogenase (LDH) isoenzymes from the liver, kidney, white muscle, heart, and eye balls. The diploid chromosome number (2n=44) and the fundamental number (NF=50) of the four tilapia genotypes were the same. However, the karyotype of O. niloticus had three pairs of sub-metacentric (sm), twelve pairs of sub-telocentric (st), and seven pairs of telocentric (t) chromosomes, while S. melanotheron had one pair of metacentric (m), two pairs of sm, 12 pairs of st, and seven pairs of t chromosomes. The reciprocal hybrids both showed a mixed karyotype range between their parents: 0.5 pair of m, 2.5 pairs of sm, 12 pairs of st, and seven pairs of t chromosomes. In view of the electropherogram of isozymes, only the LDH of the kidney showed significant clear bands, with five bands in O. niloticus, three bands in S. melanotheron, and duplicated six bands in the hybrids. The bands varied depending on their activities and mobilities. We considered that the differences in karyotype and isoenzyme were related to the genetic mechanism for post-mating isolation, and provided some additional basic genetic background of their taxonomy.

A karyological analysis of Puntius conchonius (Hamilton, 1822) (Pisces, Cyprinidae), a new cytotype from Dal Lake Srinagar Kashmir, Jammu and Kashmir (JK), India

The karyotypic and cytological characteristics of Rosy barb, Puntius conchonius (Hamilton, 1822) (cyprinidae) were investigated by examining metaphase chromosomes spreads from the anterior kidney following Thorgaard and Disney (1990). The fishes were obtained from the local fishermen and transported live to the Limnology and Fisheries Laboratory of Centre of Research for Development, University of Kashmir. Ten fish were injected intraperitoneally with two doses of phytohemagglutinin (PHA), 4 µg g-1body weight with a 20 h interval to induce cell division. After 8 h in 20°C water, the fish were injected intraperitoneally with colchicine 0.05% at 0.5 ml/50 g body weight to depress the cell division in the metaphase stage and left for 2 to 3 h before sacrificing. Kidney and gill epithelia were used for karyotype analysis. The diploid chromosome number of the fish was 2n = 50, consisting of 11 pairs of metacentric, 8 pairs of submetacentric and 6 pairs of telocentric chromosomes respectively. Centromeric index, arm ratio and Fundamental Number were determined as 0 to 50, 1-∞ and 88 respectively. No heteromorphic sex chromosomes were cytologically detected. Key words: Chromosome, Puntius conchonius, Dal Lake, karyotype.

Comparative cytogenetics of eight species of Cycloramphus (Anura, Cycloramphidae)

Several aspects of the biology of Cycloramphus species of the Atlantic Forest are still poorly known, which makes it difficult to understand their historical relationships. Therefore, we were stimulated to promote a comparative cytogenetic analysis of several species of the genus Cycloramphus. The study of Cycloramphus acangatan, C. boraceiensis, C. brasiliensis, C. carvalhoi, C. eleutherodactylus, C. fuliginosus, C. lutzorum, and C. rhyakonastes, revealed that these eight species share a diploid number 2 n = 26. Cycloramphus fuliginosus presented the most distinct karyotype, due to the presence of subtelocentric chromosomes in pairs 1 and 4. The main diagnostic feature observed in the other species was the presence of one pair of telocentric chromosomes in C. boraceiensis, C. carvalhoi, and C. eleutherodactylus, while the remaining species presented karyotypes composed exclusively of biarmed chromosomes. Constitutive heterochromatin was predominantly located in pericentromeric regions in all species, although additional C-bands detected on telomeric and/or interstitial regions were partially species-specific. Silver staining revealed Ag-NORs located on the pair 6 in six species, whereas C. acangatan presented it on pair 1 and a multiple pattern was observed in C. fuliginosus with three Ag-NOR bearing chromosomes. Fluorescent in situ hybridization using rDNA probe was performed in specimens of C. eleutherodactylus from Paraná, C. lutzorum, and C. rhyakonastes, which did not reveal inactive NOR. Despite the apparent highly conserved diploid number, data on the karyotype microstructure characterize the cytogenetic profile of the genus and may contribute to clarify the phylogenetic relationships among Cycloramphus, the Cycloramphinae, or even the family Cycloramphidae.

Karyotypes of 2 Species, Meretrix lusoria and M. petechialis, of Veneridae in Korea

The karyotypes of Meretrix lusoria and M. petechialis in the family Veneridae in Korea were studied in order to analyse their genetic relationships. The 2 species showed a diploid chromosome number of 2n=38, with 5 metacentric, 10 submetacentric, 2 subtelocentric, and 2 telocentric chromosome pairs for Meretrix lusoria, and 5 metacentric, 9 submetacentric, 3 subtelocentric, and 2 telocentric for M. petechialis. The karyotypes of these 2 species are clearly different in the same genus.

Análisis del tamaño del genoma y cariotipo de Agave aktites Gentry (Agavaceae) de Sonora, México

Genome size and karyotype structure of 2 wild populations of Agave aktites Gentry from Las Bocas and San Carlos, Sonora, Mexico were determined. Nuclear DNA content of leaf tissue was measured through flow cytometry, and chromosomes were observed in mitotic metaphase of root tips. All individual plants studied in both populations are diploids (2n= 2x= 60). The mean 2C nuclear DNA content was 8.404 pg; 1Cx= 4 120 million of base pairs. All plants of the 2 populations of A. aktites show a bimodal karyotype consisting of 10 large + 50 small chromosomes and corresponded to 46m+6st+8t; they also have a pair of large telocentric chromosomes with secondary constriction. The arm ratio was different in pair numbers 7, 8, 14 and 16 of the small chromosome group and there are morphological differences in these chromosomes between the 2 populations studied. These chromosome rearrangements may be due to spontaneous heterozygous chromosomal exchange and they are evidence that the genome of A. aktites is in active process of differentiation among populations that could lead to speciation. These analyses are fundamental for understanding the intraspecific genetic diversity in A. aktites and establishing in situ and ex situ conservation strategies for this species.

First karyological analysis of smallmouth lotak, Cyprinion kais Heckel, 1843, an endemic Cyprinid fish from the Tigris–Euphrates Basin

Karyotype of the smallmouth lotak, Cyprinion kais Heckel, 1843 (Cyprinidae) was investigated by examining metaphase chromosomes. This study is the first karyological survey on this vulnerable fish species in the Tigris–Euphrates basin. The results can be used for population studies, management and conservation programs. The fish were caught by electrofishing from Godarkhosh River in Ilam province, western Iran, in April 2008 and transported live to the Ichthyology Laboratory of Isfahan University of Technology. Five fish were injected intraperitoneally with two doses of phytohemagglutinin (PHA), 4 μg g−1 bw with a 20-h interval to induce cell divisions. After 8 h in 20°C water, the fish were injected intraperitoneally with colchicine (25–50 μg g−1 bw) to depress cell divisions in the metaphase stage and left for 7 h before sacrificing. Kidney and gill epithelia were used for karyotype analyses. It was determined that C. kais has 2n = 50 chromosomes, consisting of 8 metacentric, 7 submetacentric, 3 subtelocentric and 7 telocentric chromosome pairs. Centromeric index, arm ratio and Fundamental Number (FN) were determined as 0–50, 1–∞, and 86, respectively. The shortest and longest chromosome was a telocentric and a submetacentric one, with 2.61 and 6.88 μm length, respectively.

Stacking pairs of disease resistance genes in wheat populations using telocentric chromosomes

Resistance of wheat to diseases such as fusarium head blight (FHB) and leaf rust is more effective and durable when resistance genes are stacked. This study investigated whether pairs of disease resistance genes will become fixed at higher frequencies in subsequent generations when placed in the hemizygous condition using telocentric chromosomes. Three pairs of telocentric chromosomes were tested for their male and female transmission to predict the fixation rate of hemizygous chromosome arms using reciprocal testcrosses. Hemizygous arm transmission was about 50% through ovules and about 75% through pollen because of pollen certation. To test if a corresponding increase in disease resistance could be observed in populations utilizing telocentric chromosomes, three resistance gene pairs were analyzed separately in three populations. These pairs were Lr16/Lr34 and Lr22a/Lr52 for resistance to leaf rust and Fhb1/Qfhs.ifa-5A for FHB resistance. Each of these gene combinations was involved in a crossing and selection scheme that identified F1 plants that were either dihybrid or double monotelodisomic (DMTD). For each resistance gene combination F3 families were produced for phenotypic testing. The Lr16/Lr34 and Lr22a/Lr52 F3 populations both showed a sharp increase in leaf rust resistance among families derived from DMTD F1 plants compared to those from dihybrid F1 plants. A smaller increased resistance was found in the FHB population. The increased frequency of resistance was attributed to pollen certation and zygotic selection against the ditelosomic and double ditelosomic conditions. We conclude that telocentric chromosomes are a viable breeding tool to fix gene stacks.

Karyological Analyses on the Australian Crayfish Cherax destructor (Decapoda: Parastacidae)

The karyotype of the Australian crayfish Cherax destructor was studied by examining metaphase chromosome spreads from the testis tissues (TE) and the mitotic cells in division from the regeneration callus of the new forming limb (FL). The sampled tissues showed the same results. A total of 111 mitotic metaphases, 67 TE + 44 FL, were examined and the diploid chromosome number ranged from 179 to 207 per metaphase with a mode at 188, the latter being considered the diploid chromosome number (2n = 188) of the species. The karyotype consisted of 70 metacentric, 42 submetacentric, 48 subtelocentric and 28 telocentric chromosome pairs. The sex chromosomes were cytologically indistinguishable.