Ag-NOR Banding Research Articles

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 .

Cytogenetics of the skinks (Reptilia, Scincidae) from Thailand; III: the first karyological study of Sphenomorphus maculatus and Jarujinia bipedalis

AbstractThis is a karyological study of male and female Sphenomorphus maculatus from Khon Kaen Province in Northeastern Thailand, and female Jarujinia bipedalis from Kanchanaburi Province in Central Thailand. Chromosomes of two species were prepared by the squash technique from the bone marrow and testis. Conventional staining and Ag-NOR banding techniques were applied to stain the chromosome with Giemsa’s solution and silver nitrate solution, respectively. The results showed that the diploid chromosome number of Sphenomorphus maculatus and Jarujinia bipedalis was 30 and the fundamental number (NF) was 44. There were eight large metacentric, two medium metacentric, four small metacentric and 16 microchromosomes in Sphenomorphus maculatus and eight large metacentric, six small metacentric, two small telocentric and 14 microchromosomes in Jarujinia bipedalis. There was no irregularly sized chromosome related to sex in either species. For Sphenomorphus maculatus, NORs are located at the telomere on the long ...

Cytogenetic characterization of Hoplias malabaricus (Bloch, 1794) from the Ctalamochita River (Córdoba, Argentina): first evidence for southernmost populations of this species complex and comments on its biogeography.

Hoplias malabaricus (Bloch, 1794), a predatory freshwater fish with a wide distribution throughout South America, represents a species complex with seven well characterized karyomorphs at the cytogenetic level. Although this species has been extensively studied in several Brazilian basins, data are still scarce for hydrographic systems from other South American countries. This study aims to characterize cytogenetically the Hoplias malabaricus populations from the Argentinean Central Region, close to the southernmost distribution of this species complex. A total of 32 specimens from the Ctalamochita River, a tributary of Lower Paraná Basin located in the province of Córdoba, were analyzed using cytogenetic techniques (Giemsa staining, C- and Ag-NOR banding and fluorescent in situ hybridization with 18S rDNA). All the specimens showed diploid number 2n=42, chromosomic formula 22m + 20sm and absence of sexual chromosomes. Thus, the analyzed populations belong to the karyomorph named A. These populations showed a remarkable degree of divergence in their cytogenetic traits such as karyotypic formula, C-banding, NORs and 18S rDNA patterns for Hoplias malabaricus from other populations bearing the same karyomorph in the Middle and Upper Paraná Basin. These findings are consistent with molecular data from a recent study (where specimens collected in the present work were included), which indicate a closer phylogenetic relationship of Hoplias malabaricus populations from the Ctalamochita River with those from the Uruguay basin and the coastal regions of South Brazil than with populations from the Middle and Upper Paraná Basin. Overall, these pieces of evidence highlight the distinctive features of Hoplias malabaricus from the Ctalamochita River, and also reveal a complex history of dispersion of these populations. The present work is the first to provide cytogenetic information and include some phylogeographic aspects of Hoplias malabaricus populations living in close proximity to the southernmost extreme of its distribution area. Therefore, this study expands significantly upon the previously known geographical coverage for karyomorph A and contributes to a better understanding of the karyotypic diversification within this species complex.

The karyotype of the great sculpin, Myoxocephalus polyacanthocephalus (Pallas, 1814) (Pisces: Cottidae), from the Russian part of the species range

The karyotype of the great sculpin, Myoxocephalus polyacanthocephalus (Pallas, 1814) (Pisces: Cottidae) from the Sea of Okhotsk and the Sea of Japan has been studied for the first time. The karyotype is stable; it consists of 40 chromosomes (4 metacentric, 2 submeta-subtelocentric, 20 subtelocentric, and 14 acrocentric chromosomes); the number of chromosomal arms is 44 + 2. Nucleolar organizer regions (NOR) are found in the telomeric region of the arm in one homologue of a pair of small metacentric chromosomes, using the Ag-NOR banding technique. A comparative analysis of the karyotype of M. polyacanthocephalus and the karyotypes of other Myoxocephalus species (M. stelleri, M. brandtii, M. jaok, M. ochotensis, and M. scorpius) has been carried out based on the main karyotype characters, as well as on the number and localization of NORs. The identified differences make it possible to differentiate the studied species, whereas the general traits indicate their taxonomic proximity.

Karyotype and Idiogram of Indian Hog Deer (<i>Hyelaphus porcinus</i>) by Conventional Staining, GTG-, High-Resolution and Ag-NOR Banding Techniques

Karyotype and Idiogram of Indian Hog Deer (<i>Hyelaphus porcinus</i>) by Conventional Staining, GTG-, High-Resolution and Ag-NOR Banding Techniques

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 .

FISH and AgNor mapping of the 45S and 5S rRNA genes in wild and cultivated species of Capsicum (Solananceae).

Chromosome number and position of rDNA were studied in 12 wild and cultivated species of the genus Capsicum with chromosome numbers x = 12 and x = 13 (22 samples). For the first time in these species, the 5S and 45S rRNA loci were localized and physically mapped using two-color fluorescence in situ hybridization and AgNOR banding. We focused on the comparison of the results obtained with both methods with the aim of accurately revealing the real functional rRNA genes. The analyzes were based on a previous work that reported that the 18S-5.8S-25S loci mostly coincide with GC-rich heterochromatic regions and likely have given rise to satellite DNAs, which are not active genes. These data show the variability of rDNA within karyotypes of the genus Capsicum, providing anchor points for (comparative) genetic maps. In addition, the obtained information might be useful for studies on evolution of repetitive DNA.

New record on karyological analysis and first study of NOR localization of parthenogenetic brahminy blind snake, Ramphotyphlops braminus (Squamata, Typhlopidae) in Thailand

This is chromosomal analysis of the brahminy blind snake, Ramphotyphlops braminus (Daudin, 1803), a newly recorded species in northeastern Thailand. Mitotic chromosomes were prepared directly from intestinal epithelia cells of five brahminy blind snakes. Conventional staining and Ag-NOR banding techniques were applied to stain the chromosomes. The results showed that the triploid chromosome number was 3n = 42, while the fundamental number (NF) was 78. The types of chromosomes were 24 macrochromosomes (19 m + 5sm) and 18 microchromosomes (9 m + 3sm + 6 t). The region adjacent to the short arm near the telomere of one in macrochromosome pair 8 showed a clearly observable nucleolar organizer region/NOR. There were no irregularly sized chromosomes related to sex. The karyotype formula for R. braminus is as follows: 3n (42) = Lm 12 + Sm 7 + Ssm 5 + 18 microchromosomes.

Caracterização citogenética de Encyclia caximboensis (Orchidaceae) cultivadas in vitro

<em>E</em><em>ncyclia caximboensis</em><span> is an Amazonian species endemic to the Serra do Cachimbo, which is located between the northern of the Mato Grosso state and the southern part of Para state. Studies reporting in vitro cultivation and cytogenetic characterization of this species are still scarce. Therefore, the objective of this work was to determine the cytogenetic characteristics and to identify the nucleolar organizer regions (NORs) of the species </span><em>E. Caximboensis</em><span>, cultivated </span><em>in vitro.</em><span> Seeds of </span><em>E. caximboensis</em><span> were disinfected using a syringe and subsequently cultivated in MS medium without growth regulators. The germination started after 20 days of culture, with the development of protocorm and 40,500 seedlings were obtained after 90 days of culture. To perform the cytogenetic characterization, root tips of 180-day-old seedlings were submitted to blocking treatment using 3 µM trifiuralin and then fixed in methanol-acetic acid solution, 3:1 (v/v). The meristems were submitted to enzymatic digestion, fixed in methanol-acetic acid solution, 3:1 (v/v) and the slides were stained using 5% Giemsa solution. Ag-NOR banding was carried out on 20-day-old slides by incubation in 50% silver nitrate solution (AgNO3) for 19 hours. The results indicated that </span><em>E. caximboensis</em><span> has 2n=2x=24 with all metacentric type chromosomes, ranging from 1.88 to 0.66 pm in length, with simple NORs in small blocks localized in the proximal region of the third chromosome pair. </span>

Karyotype homology between Calotes versicolor and C. mystaceus (Squamata, Agamidae) from northeastern Thailand

Karyotypes of Calotes versicolor and Calotes mystaceus from Khon Kaen Province, northeastern Thailand were investigated. Chromosome preparations were conducted by squash technique from bone marrow. Conventional Giemsa staining and Ag-NOR banding technique were applied to stain the chromosomes. The results showed that the diploid number of C. versicolor and C. mystaceus were 34 in both the species, while the fundamental number (NF) was 46 in both sexes of these species. The types of chromosomes were: four large metacentric, two large submetacentric, four medium metacentric, two small metacentric and 22 microchromosomes in the genus Calotes. NORs of these species were located at the secondary constriction to the telomere on the long arm of the large submetacentric chromosome pair no. 2. No difference was found in karyotypes of chromosomes prepared from the male and female agamid lizards used in the present study. The karyotype formulae of C. versicolor and C. mystaceus were found to be the same and were presented as 2n (34) = Lm4 + Lsm2 + Mm4 + Sm2 + 22 microchromosomes.

Genotoxicity evaluation of environmental pollutants using analysis of nucleolar alterations.

Nucleolar alterations resulting from the action of either chemical or physical agents can serve as important genotoxicity biomarkers. In this study, the efficiency of AgNOR banding technique to identify the presence of nucleoli in micronucleus and assess nucleolar alterations in aberrant cells of Allium cepa was evaluated. Seeds of this plant were exposed to both water samples from a river that receives untreated urban effluent and to the trifluralin herbicide (0.84mg/L concentration), both analyzed in two different seasons (summer and winter seasons). Samples induced significant frequencies of chromosomal and nuclear aberrations and micronuclei, as observed in cells submitted to conventional chromosomal staining. The herbicide caused a significant increase in the number of nucleoli and micronuclei, interpreted as due to the elimination of excessive nucleolar material resulting from polyploidization. The use of the AgNOR technique enabled the identification of both the presence of the nucleolus in some micronuclei and the nucleolar organizer region (NOR) behavior of aberrant cells. The NOR-banding technique showed to be an efficient tool for studying the genotoxic effects caused by a xenobiotics and a complex environmental sample.

Distribution of constitutive heterochromatin and nucleolar organizer regions (NORs) inMustela nivalisLinnaeus, 1766 (Carnivora, Mustelidae) in Turkey

C- and Ag-NOR banding of the least weasel, Mustela nivalis, from the central and Mediterranean regions of Turkey was examined for the first time in this study. The chromosome set was composed of 18 biarmed and three acrocentric autosome pairs. The X chromosome was a medium-sized submetacentric, while the Y was a small metacentric. A distinct secondary constriction was observed on the juxta centromeric region of the long arm of an autosome that was negatively C-banded. Large heterochromatic C-blocks, stained densely, were detected in six biarmed pairs, while ones stained faintly were recorded in four biarmed autosome pairs. Active NORs were located in the secondary constriction of the acrocentric autosome. The numbers of C-banded autosomes of Turkish specimens were similar to those reported previously from the Palearctic region.

Cytogenetic Characterization of the Genome of Interspecies Hybrids (Alopex-Vulpes)

Abstract Creation of interspecific hybrids is widely common among plants and animals in order to improve economically important traits for humans. The studied material consisted of chromosomal preparations in the metaphase stage obtained from interspecies hybrids of arctic foxes (Alopex lagopus) and red foxes (Vulpes vulpes). The aim of the study was to analyze the karyotype of the interspecific hybrids taking into account the number of chromosomes of sets A and B. With the use of techniques of classical cytogenetics (C bands, AgNOR bands) and molecular cytogenetics (FISH, PRINS) we carried out a genome analysis of Alopex-Vulpes hybrids. The results of this study showed that chromosomal markers of the interspecies hybrids are inherited from the parent species and are a result of combination of their two genomes. However, intraindividual differences are also observed which may result from aberrations of chromosome segregation during embryonic development. This may lead to the formation of different cell lines with different karyotypes (mosaicism). Moreover, chromosomes of the interspecies hybrids showed telomeric signals at the ends, in the centromers, as well as short chromosome arm rich in heterochromatin. The use of PRINS method led to identification of nucleolus organizer regions on 12 chromosomes of the interspecies hybrids. The hybridization signals obtained were characterized by different size and intensity. In addition, single copies of rDNA in the centromeric regions of several metacentric chromosomes were identified.

강도다리(Platichthys stellatus)에 대한 세포유전학적 연구

【Cytogenetic analysis was conducted to obtain basic information for chromosome manipulation of starry flounder Platichthys stellatus. Nuclear surface area and volume of erythrocyte were $7.60{\pm}0.93{\mu}m^2$ and $12.80{\pm}1.75{\mu}m^3$ , respectively. The haploid DNA content of the species was 0.66 pg/haploid cell which correspond to 93% of olive flounder Paralichthys olivaceus. A karyotype analysis was also carried out with the species using conventional staining and Ag-NOR banding techniques. It was consisted of 48 acrocentric chromosomes and inter-sex or intra-individual polymorphism was not detected in all specimens analyzed. The NOR regions, appearing a terminal position of the short arm of the smallest acrocentric pairs.】

Functional repetitive sequences and fragile sites in chromosomes of Lolium perenne L.

Lolium perenne is considered a high-quality forage widely used in temperate regions to meet the shortage of forage during the winter. In this species, some peculiarities related to cytogenetic aspects have already been described, as the variability in number and position of 45S ribosomal DNA (rDNA) sites and the expression of fragile sites, which require further studies to support the understanding of their causes and consequences. In this way, this study aimed to evaluate the relationship between the expression of fragile sites and functional repetitive sequences (rDNA and telomeric) in chromosomes of diploid and polyploid cultivars of L. perenne. The techniques of FISH, Ag-NOR and fluorescence banding were used to assess the distribution of sites of 45S rDNA, 5S, telomeric sequences, and the transcriptional activity of the 45S ribosomal genes and the distribution of AT- and/or GC-rich sequences in L. perenne, respectively. There was variability in the number and location of 45S rDNA sites, which was not observed for 5S rDNA sites. One of the genotypes showed two 45S rDNA sites on the same chromosome, located in different chromosome arms. Breaks and gaps were found in 45S rDNA sites in most metaphases evaluated for both cultivars. Telomeric sequences were not detected at the end of the chromosomal fragments corresponding to the location of breaks at 45S sites. Apparently, the transcriptional activity was modified in fragile sites. Variation in the number and size of nucleoli, nucleolar fusions and dissociations were observed. All CMA(+) bands were colocalized with the 45S sites.

Cytogenetic and identification of the nucleolus organizer region in Heliconia bihai (L.) L.

The genus Heliconia is not much studied and the number of existing species in this genus is still uncertain. It is known that this number relies between 150 to 250 species. In Brazil, about 40 species are native and known by many different names. The objective of this paper was to characterize morphometrically and to identify the NOR (active nucleolus organizer regions) by Ag-NOR banding of chromosomes of Heliconia bihai (L) L. Root meristems were submitted to blocking treatment in an amiprofos-methyl (APM) solution, fixed in methanol-acetic acid solution for 24 hours, at least. The meristems were washed in distilled water and submitted to enzymatic digestion with pectinase enzyme. The slides were prepared by dissociation of the root meristem, dried in the air and also on hot plate at 50°C. Subsequently, some slides were submitted to 5% Giemsa stain for karyotype construction and to a solution of silver nitrate (AgNO3) 50% for Ag-NOR banding. The species H. bihai has 2n = 22 chromosomes, 4 pairs of submetacentric chromosomes and 7 pairs of metacentric chromosomes, and graded medium to short (3.96 to 0.67 μM), with the presence of active NOR in pairs 1 and 2 and interphase cells with 2 nucleoli. These are the features of a diploid species.

Similarities and differences among the chromosomes of the wild guinea pig Cavia tschudii and the domestic guinea pig Cavia porcellus (Rodentia, Caviidae).

Cavia tschudii Fitzinger, 1867 is a wild guinea pig species living in South America that according to the analysis of mitochondrial genes is the closest wild form of the domestic guinea pig. To investigate the genetic divergence between the wild and domestic species of guinea pigs from a cytogenetic perspective, we characterized and compared the C, G and AgNOR banded karyotypes of molecularly identified Cavia tschudii and Cavia porcellus Linnaeus, 1758 specimens for the first time. Both species showed 64 chromosomes of similar morphology, although C. tschudii had four medium size submetacentric pairs that were not observed in the C. porcellus karyotype. Differences in the C bands size and the mean number of AgNOR bands between the karyotypes of the two species were detected. Most of the two species chromosomes showed total G band correspondence, suggesting that they probably represent large syntenic blocks conserved over time. Partial G band correspondence detected among the four submetacentric chromosomes present only in the C. tschudii karyotype and their subtelocentric homologues in C. porcellus may be explained by the occurrence of four pericentric inversions that probably emerged and were fixed in the C. tschudii populations under domestication. The role of the chromosomal and genomic differences in the divergence of these two Cavia species is discussed.

Cytogenetic study of Leptodactylus fuscus and L. latrans (Anura: Leptodactylidae) from the semiarid Brazilian Caatinga scrublands

Frogs in the family Leptodactylidae have diploid chromosome numbers ranging from 2n = 18 to 2n = 26, although there is a predominance of 2n = 22 karyotypes. In the present sudy, 52 specimens of Leptodactylus latrans were obtained from three muncipalities (Carira. Poco Redondo, and Tobias Barreto) of the Brazilian state of Sergipe for karyotype analysis using conventional Giemsa staining techniques, and C- and Ag-NOR banding of the chromosomes obtained from the intestinal epithelium. The results of this study show that the individuals analyzed have highly similar karyotypes, with no evidence of any pronounced species-specific markers. However, some differences were observed in the chromosome morphology and C-bands in comparison with the karyotypes described previously for these species, with may represent intraspecific geographic variation in both taxa.

Chromosome Analysis and Morphometric of Intermediate Roundleaf Bat, Hipposideros larvatus (Chiroptera, Hipposideridae) by Conventional, GTG-banding and Ag-NOR Banding Techniques

Chromosome Analysis and Morphometric of Intermediate Roundleaf Bat, Hipposideros larvatus (Chiroptera, Hipposideridae) by Conventional, GTG-banding and Ag-NOR Banding Techniques

Standardized Karyotype and Idiogram of Quoy's Parrotfish, Scarus quoyi (Perciformes: Scaridae) by Conventional Staining and Ag-NOR Banding Techniques

Standardized Karyotype and Idiogram of Quoy's Parrotfish, Scarus quoyi (Perciformes: Scaridae) by Conventional Staining and Ag-NOR Banding Techniques