Ag-NOR Banding Research Articles

Cytogenetic comparison of Podocnemis expansa and Podocnemis unifilis: a case of inversion and duplication involving constitutive heterochromatin

Podocnemis expansa and P. unifilis present 2n = 28 chromosomes, a diploid number similar to those observed in other species of the genus. The aim of this study was to characterize these two species using conventional staining and differential CBG-, GTG and Ag-NOR banding. We analyzed specimens of P. expansa and P. unifilis from the state of Tocantins (Brazil), in which we found a 2n = 28 and karyotypes differing in the morphology of the 13th pair, which was submetacentric in P. expansa and telocentric in P. unifilis. The CBG-banding patterns revealed a heterochromatic block in the short arm of pair 13 of P. expansa and an interstitial one in pair 13 of P. unifilis, suggesting a pericentric inversion. Pair 14 of P. unifilis showed an insterstitial band in the long arm that was absent in P. expansa, suggesting a duplication in this region. Ag-NORs were observed in the first chromosome pair of both species and was associated to a secondary constriction and heterochromatic blocks.

Chromosomal Rearrangements Occurred Repeatedly and Independently during Species Diversification in Malagasy Geckos, GenusParoedura

We conducted a phylogenetic study through karyological data, by standard staining and Ag-NOR banding, and molecular analysis (by 12S and 16S mitochondrial rRNA genes and nuclear gene C-mos) on 11 species of Malagasy geckos, genus Paroedura, and two relatives (Ebenavia inunguis and Uroplatus phantasticus). Ebenavia inunguis and 17. phantasticus had 2n = 36 telocentric elements, NORs on the first chromosome pair in E. inunguis, and on the third chromosome pair in U. phantasticus. All examined Paroedura showed NORs on the smallest chromosome pair; moreover, six of the eleven examined species show a 2n = 36 karyotype, with a pair of metacentrics and 17 telocentric pair. The remaining species exhibited karyotypes with a diploid chromosome number ranging from 2n = 31 to 2n = 38. We assume that these karyotype assemblages derived from the 2n = 36 karyotype by cryptic and/or simple rearrangements, such as inversions, fissions and fusions. Furthermore, molecular and/or chromosomal data indicate that Paroedura is a monophyletic genus, in which chromosome rearrangements occurred repeatedly and independently during the specific diversification. Moreover both P. bastardi and P. gracilis in current definitions are paraphyletic assemblages of several related species, since their population proves more closely related to P. ibityensis or P. oviceps than co-specific populations. Key words: chromosome, Gekkonidae, Madagascar, Paroedura, molecular phylogeny.

Chromosomal rearrangements occurred repeatedly and independently during species diversification in Malagasy geckos, genus Paroedura

We conducted a phylogenetic study through karyological data, by standard staining and Ag-NOR banding, and molecular analysis (by 12S and 16S mitochondrial rRNA genes and nuclear gene C-mos) on 11 species of Malagasy geckos, genus Paroedura, and two relatives (Ebenavia inunguis and Uroplatus phantasticus). Ebenavia inunguis and U. phantasticus had 2n = 36 telocentric elements, NORs on the first chromosome pair in E. inunguis, and on the third chromosome pair in U. phantasticus. All examined Paroedura showed NORs on the smallest chromosome pair; moreover, six of the eleven examined species show a 2n = 36 karyotype, with a pair of metacentrics and 17 telocentric pair. The remaining species exhibited karyotypes with a diploid chromosome number ranging from 2n = 31 to 2n = 38. We assume that these karyotype assemblages derived from the 2n=36 karyotype by cryptic and/or simple rearrangements, such as inversions, fissions and fusions. Furthermore, molecular and/or chromosomal data indicate that Paroedura is a monophyletic genus, in which chromosome rearrangements occurred repeatedly and independently during the specific diversification. Moreover both P. bastardi and P. gracilis in current definitions are paraphyletic assemblages of several related species, since their population proves more closely related to P. ibityensis or P. oviceps than co-specific populations.

Cytogenetic studies in four cultivated Amaranthus (Amaranthaceae) species

In the present study, the chromosomes numbers were confirmed, 2n = 34 for Amaranthus cruentus Linnaeus, 1759, and 2n = 32 for Amaranthus hypochondriacus Linnaeus, 1753, Amaranthus mantegazzianus Passer, 1864, and Amaranthus caudatus Linnaeus, 1753. The distribution and variability of constitutive heterochromatin were detailed using DAPI-CMA3 banding technique. The position of the nucleolus organizer region (NOR) was observed using Ag-NOR banding (active loci) and fluorescent in situ hybridization (rDNA-FISH) in the four Amaranthus species. Variations in the amount of constitutive heterochromatin were detected both within the species and between them, with DAPI-CMA3 stain. One chromosome pair having a NOR was found in each studied accession, with exception of Amaranthus caudatus cv. EEA INTA Anguil. This accession presented four rDNA loci (FISH), being active two of them (Ag- banding).

First Cytogenetic Study of Puff-Faced Water Snake, <i>Homalopsis buccata</i> (Squamata, Colubridae) by Conventional Staining, Ag-NOR Banding and GTG-Banding Techniques

Summary The first cytogenetics of the puff-faced water snake (Homalopsis buccata) from Khon Kaen Province, Thailand was obtained from the present study. Mitotic chromosome was prepared directly from the spleens of specimens after in vivo colchicines treatment. The metaphase spreads were performed on microscopic slides and air-dried. Conventional staining, Ag-NOR banding, and GTG-banding techniques were applied to stain the chromosome with Giemsas solution. Results showed that the number of diploid chromosome was 2n=36, while the fundamental number (NF) was 52 in both males and females. The types of macrochromosome were four large metacentric, two medium metacentric, six small metacentric, and two small acrocentric chromosome, and 20 micro- chromosomes. It was found that nucleolar organizer regions (NORs, the representative of chromo- some marker) locate on the long arms near centromeres of a pair of microchromosomes, pair 15. The Z chromosome was a small metacentric chromosome, while the W chromosome was a small sub- metacentric chromosome. From the GTG-banding technique, it was found that each chromosome pairs could be clearly differentiated and the numbers of bands in the H. buccata was 109. The karyo- type formula is as follows: 2n (36)=L m 4 +M m 2 +S m 6 +S a +20 microchromosomes+sex chromosomes (ZW)

Standardized Karyotype and Idiogram of Titan Triggerfish, <i>Balistoides viridescens</i> (Tetraodontiformes, Balistidae) in Thailand

The standardized karyotype and idiogram of the titan triggerfish, Balistoides viridescens (Bloch & Schneider 1801) from Phuket Province, Thailand, were obtained from the present study. Kidney cell samples were taken from five male and five female fish. The mitotic chromosome preparations were conducted directly from the kidney cells. Conventional staining and Ag-NOR banding techniques were applied to stain the chromosomes. The results indicated that the diploid chromosome number of B. viridescens was 2n=44, and the fundamental number (NF) was 60 in both sexes. The chromosome types consist of 2 large metacentric, 4 large acrocentric, 2 large telocentric, 8 medium acrocentric, 10 medium telocentric, 2 small acrocentric, and 16 small telocentric chromosomes. No strange-sized chromosomes related to sex was observed. The region adjacent to the subtelomeric of short arm of chromosome pair 3 showed clearly observable secondary constriction/NORs. The karyotype formula for B. viridescens is as follows: 2n (diploid) 44=L2 +La 4+L2+M8+M10+S 2+S16

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.

First record of supernumerary (B) chromosomes in electric fish (Gymnotiformes) and the karyotype structure of three species of the same order from the upper Paraná River basin

Cytogenetic studies were performed on the species Apteronotus prope albifrons Linnaeus, 1766, Rhamphichthys hahni Meinken, 1937 and Brachyhypopomus gauderio Giora & Malabarba, 2009, collected in the upper Paraná River floodplain, Porto Rico (PR), Brazil. Apteronotus prope albifrons showed a diploid number of 2n=24 chromosomes for both sexes and a karyotype formula of 14m+2sm+2st+6a (FN=42). Besides the standard karyotype, three specimens had one to three extra microchromosomes with inter- and intra-individual variations, which suggested the occurrence of B chromosomes in the species. The chromosomal data of Rhamphichthys hahni, described here for the first time, consists of 50 chromosomes and a formula comprised of 20m+24sm+6a (FN=94). Brachyhypopomus gauderio specimens demonstrated 2n=42 chromosomes infemales, all acrocentric, and 2n=41 chromosomes in males, with 40 acrocentric and 1 medium-sized metacentric chromosome. These differences concern with a multiple system of sexchromosome determination X1X1X2X2/X1X2Y (FN=42) in Brachyhypopomus gauderio. The analysis of nucleolar organizer regions by Ag-NOR and FISH 18S banding revealed a simple NOR system in Apteronotus prope albifrons and Rhamphichthys hahni and a multiple NOR system in Brachyhypopomus gauderio, that is unusual for Gymnotiformes fishes. Constitutive heterochromatin was mainly found in the pericentromere region in most of the chromosomes of the three species, although each species had its own peculiarities. The B chromosomes in Apteronotus prope albifrons demonstrated heterochromatin positioned in the centromeric and telomeric regions whereas Rhamphichthys hahni presented conspicuous blocks of heterochromatin on the long arms in three submetacentric pairs. Brachyhypopomus gauderio showed blocks of heterochromatin on the long arm in the interstitial and telomere positions. The finding of B chromosomes in Apteronotus prope albifrons represents the first description of these elements in the Gymnotiformes order. Although the karyotype of this species is similar with that described for populations in the Amazon basin, the presence of B chromosomes could represent a specific characteristic of this population. A comparative analysis of karyotypes of Rhamphichthys hahni with other species of the genus showed a relatively conservative structure suggesting 2n=50 as a common number in this group. The karyotype of Brachyhypopomus gauderio, a new species, provides an important reference for future chromosome studies of the Brachyhypopmus Mago-Lecia, 1994, and it might be also significant for cytotaxonomy in this group. The cytogenetic data also demonstrate the need of more comparative cytogenetic studies in the families of the highly diversified and taxonomically difficult complex Gymnotiformes.

Localization of Nucleolar Organizer Regions (NORs) of 4 Gibbon Species in Thailand by Ag-NOR Banding Technique

Summary Localization of nucleolar organizer regions (NORs) of four gibbon species in Thailand was studied. Blood samples were taken from 1 male each of the following 3 species: white-handed gibbon (Hylobates lar), pileated gibbon (H. pileatus), and white-cheeked gibbon (Nomascus leucogenys): and 1 female of the dark-handed gibbon (H. agilis). These were subjected to standard whole blood T-lymphocyte culture. The samples were harvested by colchicine-hypotonic-fixation-air-drying technique and were followed by the Ag-NOR banding technique. The results showed that the H. lar had NORs on chromosome pair 13 (submetacentric chromosomes) while the H. agilis had NORs on chromosome pair 10 (submetacentric chromosomes) and H. pileatus had NORs on chromosome pair 15 (metacentric chromosomes). In addition, the N. leucogenys showed 5 positions with NORs on chromosomes pairs 23, 24 (acrocentric chromosomes) and the Y-chromosome (submetacentric chromosome). These results are useful to confirm marker chromosomes of gibbons and also comprise basic genetic information for these animals. Kew words Gibbon, Karyotype, Chromosome, Idiogram, Ag-NOR banding. Thailand is tropical country thus its weather and surrounding are suitable for organism that causes high diversity. Wild animals are one element that show the diversity and also important in ecology and food chain. The destruction of forest causes wild animal extinction or risk of extinction includes animal in family Hylobatidae. There were 13 families, 60 genera and 232 species of animals in order Primate (Wilson and Cole 2000); however, only 3 families, 5 genera, and 13 species were found in Thailand. Thai gibbon species consists of 4 species, white-handed gibbon (Hylobates lar Linnaeus 1771), agile gibbon or dark-handed gibbon (Hylobates agilis Cuvier 1821), pileated gibbon (Hylobates pileatus Gray 1842), and white-cheeked gibbon (Nomascus leucogenys Ogilby 1840) (Lekagul and McNeely 1988, Giessmann 1995) (Fig. 1). These species are listed as protected species in Wild Animal Reservation and Protection Act (1992), and in the International Union for the Conservation of Nature (IUCN) as vulnerable species. The Convention on International Trade in Endangered Species (CITES) of wild fauna and flora also listed these species in Appendix I (Brokelman 1981).

Karyotype characterization of two populations of Vernonia geminata (Asteraceae, Vernonieae) using banding and FISH techniques

In order to extend our knowledge concerning karyotypes of the genus Vernonia, we applied various techniques of chromosome banding, including AgNOR and triple staining with the fluorochromes CMA/DA/DAPI (CDD), and of fluorescent in situ hybridization (FISH) for the 45S rDNA probe to specimens of two populations of Vernonia geminata collected from an open-pasture area, in southern Brazil. B chromosomes were observed in one of the populations. Both populations of V. geminata presented a pair of CMA(3)(+) terminal bands and one pair of chromosomes with terminal AgNOR banding. The FISH evidenced, in one population, two pairs of small sites of 45S rDNA; these being two small terminal sites and two centromeric sites. In the other population, there was only one pair of small terminal sites and two sites in two B chromosomes, one in each chromosome. There was coincidence of localization between CMA(+) and NOR bands with one of the small terminal sites of 45S rDNA of one chromosome of the normal complement, but not in B chromosomes.

A cytogenetical study on Economidichthys pygmaeus Holly, 1929 (Pisces, Gobiidae), an endemic freshwater goby from Western Greece

A cytogenetic study was carried out on the chromosomes and the nuclear DNA content of the freshwater goby Economidichthys pygmaeus (Pisces, Gobiidae). The species is characterized by a 2n=46 karyotype consisting of 12 submetacentric and 11 subtelocentric chromosome pairs (NF=70). Major (45S) rDNA genes are terminal-centromeric located on the short arm of a single medium-small sized submetacentric pairas assessed by in situ hybridization, CMA3 staining, and Ag-NOR banding. The haploid (C-value) nuclear DNA content is 0.93±0.003 picograms. The cytogenetical data of Economidichthys pygmaeus were compared with those ones already available for other related gobies.

Study of karyotype and Nucleolar Organizer Regions (NORs)<br>in wild, synthetic and cultivated wheats

Wild relatives of bread wheat are potential sources of valuable genetic materials for wheat improvement. Karyotype analysis plays an important role in the identification and designation of chromosomes in many plant species. In this study, the karyotype features and nucleolar organizer regions (NORs) of 21 wheat genotypes representing diploid, tetraploid and hexaploid species and belonging to wild, cultivated and synthetic groups were investigated. Total chromosome length (TCL) values vary across the genotypes. The highest value (99.1 µm) was recorded in one of a synthetic hexaploid wheat (Doy1/ Ae. squarrosa (458)) with a mean chromosome length (MCL) of 5.67±0.59 µm, while the lowest value (39.48µm) was found in T. monococcum species with a mean chromosome length (MCL) of 4.06±0.51 µm. Cluster analysis based on chromosomal characteristics and karyotype asymmetry indices including symmetry index (S %), total form percentage (TF %), Romero-Zarco's indices (A1and A2) and Stebbin's classification divided the genotypes into three groups. Results revealed that group 1, including synthetic hexaploid wheat accessions, had the most asymmetric karyotype in terms of centromere position and chromosome length. Ag-NOR banding identified two nucleolus organizer regions (NORs) on the long arms of the chromosomes 1B and 6B in both tetraploid and hexaploid wheats.

Robertsonian Translocation [56,XX and 57,XY,rob(1;29)] in Captive Thai Gaur (Bos gaurus readei) by Conventional, GTG-Banding, CBG-Banding and Ag-NOR Banding Techniques

Robertsonian translocation, or centric fusion, which is known to be the most common mechanism in karyotype evolution of bovid species, was observed and described in captive Thai gaur (Bos gaurus readei). Blood samples were taken from 2 male and 2 female captive Thai gaur. 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, GTG-banding, CBG-banding and Ag-NOR banding techniques were applied to stain the chromosomes. The number of diploid chromosomes (2n) were 57 in 2 males and 56 in 2 females instead of the normal 2n=58. The fundamental number (NF) was 62 in both the 2 males and 2 females. The autosome consists of 3 submetacentric and 52 telocentric chromosomes in males, and 4 submetacentric and 50 telocentric chromosomes in females. The X chromosome was a large submetacentric chromosome and the Y chromosome was the smallest metacentric chromosome. Eight telocentric chromosomes and 2 submetacentric chromosomes (5 autosome pairs) were identified as satellite chromosomes which showed clearly observable nucleolar organizer regions (NORs). The presence of an extra submetacentric chromosome and the loss of 2 telocentric chromosomes [57,XY,rob(1;29)] were observed in both males. Also, the presence of 2 extra submetacentric chromosomes and the loss of 4 telocentric chromosomes [56,XX,rob(1;29)] were observed in both females. Results from the GTG-banding and CBG-banding techniques analyses confirmed that the 2 autosomes of male (2n=57) and 4 autosomes of female (2n=56) involved in the translocation are the chromosome pairs 1 and 29, which are common in translocation of the bovid species.

B Chromosomes in Nierembergiaaristata (Solanaceae): Nucleolar Activity and Competition with the A Chromosomes

B chromosomes are additional dispensable chromosomes that may be present in some individuals, populations, or species, which have probably arisen from the A chromosomes but follow their own evolutionary pathway. Supposedly, B chromosomes do not contain major genes except for ribosomal DNA (rDNA) sequences that have been mapped on the supernumerary chromosomes of many plants and animals. This paper is a new report of B chromosome occurrence in plants. B chromosomes with nucleolar organizing regions (NORs) were found in a diploid sample of Nierembergiaaristata D. Don (sub nom. N. stricta Miers) (2n = 2x = 16). This is an extreme case in which B chromosomes possess not only strong nucleolar activity, as revealed by conventional staining methods, AgNOR and fluorescence banding, and fluorescent in situ hybridization (FISH), but also show nucleolar competition with the A chromosomes. The observed phenomenon could be analogous to the nucleolar dominance or ‘differential amphiplasty’ phenomenon that occurs in interspecific hybrids.

Description of the karyotype of Rhagomys rufescens Thomas, 1886 (Rodentia, Sigmodontinae) from Southern Brazil Atlantic forest

Rhagomys rufescens (Rodentia: Sigmodontinae) is an endemic species of the Atlantic forest from Southern and Southeastern Brazil. Some authors consider Rhagomys as part of the tribe Thomasomyini; but its phylogenetic relationships remain unclear. Chromosomal studies on eight specimens of Rhagomys rufescens revealed a diploid number of 2n = 36 and a number of autosome arms FN = 50. GTG, CBG and Ag-NOR banding and CMA3 /DAPI staining were performed on metaphase chromosomes. Eight biarmed and nine acrocentric pairs were found in the karyotype of this species. The X and Y chromosomes were both acrocentric. Most of the autosomes and the sex chromosomes showed positive C-bands in the pericentromeric region. The X chromosome showed an additional heterochromatic block in the proximal region of the long arm. Nucleolus organizer regions (NORs) were located in the pericentromeric region of three biarmed autosomes (pairs 4, 6 and 8) and in the telomeric region of the short arm of three acrocentrics (pairs 10, 12 and 17). CMA 3 /DAPI staining produced fluorescent signals in many autosomes, especially in pairs 4, 6, and 8. This study presents cytogenetic data of Rhagomys rufescens for the first time.

Chromosome Polymorphism in Phyllomedusa rohdei Populations (Anura: Hylidae)

The range of Phyllomedusa rohdei was recently extended to the state of Bahia, Brazil. Cytogenetic analysis through conventional Giemsa staining and Ag-NOR banding of P. rohdei samples from two localities in the Atlantic Rainforest, state of Bahia revealed intraspecific karyotype variation. Although all individuals showed the diploid number of 2n = 26, variations in the karyotypic formula were observed. The greatest variation was found in the length of first chromosome pair. The Ag-NOR banding identified variability in the number of stained chromosomes, which ranged from two to four banded chromosomes per individual. The results revealed the preliminary stages of chromosomal differentiation within this species.

Karyological Observations in Medicago Section Dendrotelis (Fabaceae)

Medicago section Dendrotelis comprises polyploid, woody shrubs restricted to rocky and cliff faces in coastal places of the Mediterranean basin, showing a very close morphology. This has resulted in controversial taxonomic studies, differing in the circumscription and number of recognized species (from one to three). In the present study, cytogenetic studies (meiotic analysis, C-banding, Ag-NOR banding) were made in M. arborea, M. strasseri, and M. citrina to determine their karyological and evolutionary relationships. The observation of meiocytes revealed a regular meiotic cycle in all species. At pachytene stage, chromosomes showed constitutive heterochromatic blocks (knobs) that were species-specific, and clearly discriminate M. arborea and M. strasseri from M. citrina. Conventional karyotypes of M. strasseri and M. arborea were similar concerning chromosome classes, the apparent chromosome length, and the morphology of the single NOR chromosome pair. However, C-banding technique revealed karyotypic differences between both species. In contrast, M. citrina exhibited a slightly asymmetric karyotype, the presence of two pairs of chromosomes showing secondary constrictions, a similar apparent chromosome length, and two pairs of active rDNA loci. Its C-banded karyotype strikingly differed from those observed in M. arborea and M. strasseri, and only three chromosome pairs showed heterochromatic blocks. These cytogenetic data indicate a clear evolutionary split in woody medics (tetraploid vs hexaploid species), reflecting divergent patterns of karyological evolution. Taken together, all karyological data unequivocally support the recognition of M. citrina as a distinct species.

Karyological Characterization of the Butterfly Lizard (Leiolepis reevesii rubritaeniata, Agamidae, Squamata) by Molecular Cytogenetic Approach

Karyological characterization of the butterfly lizard (Leiolepis reevesii rubritaeniata) was performed by conventional Giemsa staining, Ag-NOR banding, FISH with the 18S-28S and 5S rRNA genes and telomeric (TTAGGG)n sequences, and CGH. The karyotype was composed of 2 distinct components, macrochromosomes and microchromosomes, and the chromosomal constitution was 2n = 2x = 36 (L₄^m + L₂^sm + M₂^m + S₄^m + 24 microchromosomes). NORs and the 18S-28S rRNA genes were located at the secondary constriction of the long arm of chromosome 1, and the 5S rRNA genes were localized to the pericentromeric region of chromosome 6. Hybridization signals of (TTAGGG)n sequences were observed at the telomeric ends of all chromosomes and interstitially at the same position as the 18S-28S rRNA genes, suggesting that in the Leiolepinae tandem fusion probably occurred between chromosome 1 and a microchromosome where the 18S-28S rRNA genes were located. CGH analysis, however, failed to identify sex chromosomes, suggesting that this species may have a TSD system or exhibit GSD with morphologically undetectable cryptic sex chromosomes. Homologues of 6 chicken Z-linked genes (ACO1/IREBP, ATP5A1, CHD1, DMRT1, GHR, RPS6) were all mapped to chromosome 2p in the same order as on the snake chromosome 2p.

Somatic Chromosomes of the Bornean Sambar Deer and Rusa Deer Interspecific Hybrids

Problem statement: Hybridization has potential benefits to the Malaysian farmed deer industries in terms of increased growth rate and increased proportion of muscle and an improved alignment of feed supply and annual energy requirement. Species or subspecies of different chromosome constitution could mate to produce healthy hybrid offspring in a normal ratio of males and females. If any of the hybrid offspring were sterile, the sterile offspring would be the heterogametic offspring. The study investigated the use of chromosome banding method to detect chromosomal variation and to define the chromosome homology and the possibility of the Bornean Sambar deer (Cervus unicolor brookei) and Rusa deer (Cervus timorensis) hybrids to reproduce. Approach: Samples were collected from the Livestock Breeding Station, Sabrang, Keningau, Sabah, East Malaysia. The animals studied consisted of two deer subspecies namely the Bornean Sambar deer, Rusa deer and their hybrids. The karyotypes of the Bornean Sambar deer, Rusa deer and their F1 hybrids have been investigated by solid giemsa staining, G-banding and Ag-NOR banding techniques. Results: Rusa and Bornean Sambar have different chromosome number; 60 and 62 respectively, but share the same fundamental number of chromosome arm, 70. The hybrids have 2n = 61, consisting of 9 metacentric to submetacentric autosomes and 24 pairs of acrocentric autosomes with two acrocentrics and one submetacentric chromosome being unpaired. The morphology of the sex chromosomes in the F1 hybrids was similar to that of the parental species. The Ag-NOR pattern and the conventional Giemsa staining of chromosomes were effective as markers in the characterization of the karyotypes of the parental lines and hybrids because of the presence of active NORs on different chromosomes of different species. G-band, in contrast, showed complete homology in the presence of euchromatic bands and heterochromatin blocks respectively on each chromosome, suggesting that the two species have few genetic differences. Conclusion: In the present study, natural mating between Bornean Sambar deer and Rusa deer were conducted and the number and chromosomal location of the nucleolar organizer regions in their offsprings were analyzed by the silver staining method. Apart from that, the interspecific dissimilarities with regards to chromosome number and morphology are less extensive and the production of chromosomally balanced gametes could be expected.

The karyotype ofCabassous unicinctus(Dasypodidae, Xenar-thra)

Abstract Armadillos was belonged to the Xenarthra Order, Dasypodidae family. This family has been comprising the largest number of genera and species among the Xenarthrans; eight (8) and 21, respectively. Two adult males of the species Cabassous unicinctus were analyzed in this study. Lymphocyte cultures from whole blood were used and the cells were then submitted to conventional staining by C- and Ag-NOR banding. Data regarding the number of chromosomes showed discrepancies among the species described in the literature. The 46 chromosomes observed were distributed in six large metacentric pairs, five medium submetacentric pairs, five medium and small metacentric pairs and six acrocentric pairs. The Y chromosome was classifed such as the smallest acrocentric of the group. The X chromosome was classifed as medium submetacentric, it considered atypical for mammals, because X was generally large size metacentric when it compared to the remaining karyotype. The diploid number reduction from 62 to 46 chromosom...