scholarly journals Karyotype characterization of Mugil incilis Hancock, 1830 (Mugiliformes: Mugilidae), including a description of an unusual co-localization of major and minor ribosomal genes in the family

2011 ◽  
Vol 9 (1) ◽  
pp. 107-112 ◽  
Author(s):  
Anne Kathrin Hett ◽  
Mauro Nirchio ◽  
Claudio Oliveira ◽  
Zoila Raquel Siccha ◽  
Anna Rita Rossi ◽  
...  
Keyword(s):  
Chromosome Pair ◽  
Chromosome Complement ◽  
5S Rdna ◽  
Gene Clusters ◽  
Ribosomal Genes ◽  
Nucleolus Organizer ◽  
The Family ◽  
Pair Number ◽  
Mugil Incilis ◽  
Secondary Constrictions

This study reports the description of the karyotype of Mugil incilis from Venezuela. The chromosome complement is composed of 48 acrocentric chromosomes, which uniformly decrease in size. Therefore, the homologues can not be clearly identified, with the exception of one of the largest chromosome pairs, classified as number 1, whose homologues may show a subcentromeric secondary constriction, and of chromosome pair number 24, which is considerably smaller than the others. C-banding showed heterochromatic blocks at the centromeric/pericentromeric regions of all chromosomes, which were more conspicuous on chromosomes 1, given the C-positive signals include the secondary constrictions. AgNO3 and fluorescent in situ hybridization (FISH) with 45S rDNA demonstrated that the nucleolus organizer regions are indeed located on the secondary constrictions of chromosome pair number 1. FISH with 5S rDNA revealed that the minor ribosomal genes are located on this same chromosome pair, near the NORs, though signals are closer to the centromeres and of smaller size, compared to those of the major ribosomal gene clusters. This is the first description of co-localization of major and minor ribosomal genes in the family. Data are discussed from a cytotaxonomic and phylogenetic perspective.

scholarly journals Cytogenetic characterization of Rhomboplites aurorubens and Ocyurus chrysurus, two monotypic genera of Lutjaninae from Cubagua Island, Venezuela, with a review of the cytogenetics of Lutjanidae (Teleostei: Perciformes)

2009 ◽  
Vol 7 (4) ◽  
pp. 587-594 ◽  
Author(s):  
Mauro Nirchio ◽  
Claudio Oliveira ◽  
Daniela C. Ferreira ◽  
Rodolfo Rondón ◽  
Julio E. Pérez ◽  
...  
Keyword(s):  
Gene Cluster ◽  
Chromosome Pair ◽  
Chromosome Complement ◽  
5S Rdna ◽  
Molecular Data ◽  
Nucleolus Organizer ◽  
Rrna Genes ◽  
Single Chromosome ◽  
Rdna Gene ◽  
The Family

Lutjanidae, commonly known as snappers, includes 105 species, grouped in four subfamilies. In spite of the high number of species and of its worldwide distribution, the family has been little investigated and the phylogenetic relationships among some of its genera and species are still cause for debate. Only a small number of the species has been cytogenetically analysed. This study reports the first description of the karyotype of Rhomboplites aurorubens as well as data concerning the distribution of the constitutive heterochromatin and the location of the 18S rRNA and the 5S rRNA genes. Specimens of Ocyurus chrysurus from Venezuela were also investigated for the same cytogenetic features. Both species have a 48 uniarmed karyotype, but R. aurorubens has a single subtelocentric chromosome pair, the smallest of the chromosome complement, among the other acrocentric chromosomes. The C-positive heterochromatin is limited to the pericentromeric regions of all chromosomes. Both species show a single chromosome pair bearing the Nucleolus Organizer Regions, but NORs are differently located, in a terminal position on the short arms of the smallest chromosomes in R. aurorubens and in a paracentromeric position in a chromosome pair of large size in O. chrysurus. In O. chrysurus, the 5S rDNA gene cluster is located on a medium-sized chromosome pair, whereas in R. aurorubens it is syntenic with the 18S rDNA gene cluster on chromosome pair number 24. The obtained cytogenetic data, along with previous cytogenetic, morphological and molecular data for the family, reinforce the proposal to synonymize genus Ocyurus with Lutjanus. A review of Lutjanidae cytogenetics is also included.

scholarly journals First chromosomal analysis of Gymnorhamphichthys britskii: the remarkable lowest diploid value within the family Rhamphichthyidae (Gymnotiformes)

2019 ◽  
Vol 17 (3) ◽  
Author(s):  
Carlos Alexandre Fernandes ◽  
Allan Kardec Moreira de Aguiar ◽  
Leonardo Marcel Paiz ◽  
Lucas Baumgärtner ◽  
Diovani Piscor ◽  
...  
Keyword(s):  
Chromosome Pair ◽  
5S Rdna ◽  
Single Pair ◽  
Submetacentric Chromosome ◽  
Single Chromosome ◽  
Heterochromatic Block ◽  
The Family ◽  
Heteromorphic Sex Chromosomes ◽  
Pair Number ◽  
Acrocentric Chromosomes

ABSTRACT Gymnorhamphichthys britskii is a Neotropical electric fish of family Rhamphichthyidae described from the Paraná-Paraguay system. This study reports the first karyotypic description of G. britskii collected from the upper Paraná river basin, which presented 2n=38 chromosomes, karyotype composed of 14 metacentric, 8 submetacentric, 2 subtelocentric and 14 acrocentric chromosomes, and fundamental number as 62 for both sexes. Heteromorphic sex chromosomes were absent. A single pair of nucleolar organizing regions (NORs) was detected in the submetacentric chromosome pair number 9 by silver staining and confirmed by the 18S rDNA probe. The 5S rDNA was located in a single chromosome pair. Heterochromatic regions were clearly observed in the short arms of the NOR-bearing chromosome pair and in the telomeric positions of most acrocentric chromosomes. Besides the present data are valuable to help in understanding karyotypic evolution in Rhamphichthyidae, data from NORs confirmed the tendency of this family in presenting simple NORs sites, similar to the other Gymnotiformes clades. Yet, the presence of a large heterochromatic block in the NOR-bearing chromosome can be used as cytogenetic markers for G. britskii, and that centric fusions appear to be an important mechanism in the karyotype evolution and differentiation among Gymnotiformes species.

scholarly journals Cytogenetic studies in three species of Lutjanus (Perciformes: Lutjanidae: Lutjaninae) from the Isla Margarita, Venezuela

2008 ◽  
Vol 6 (1) ◽  
pp. 101-108 ◽  
Author(s):  
Mauro Nirchio ◽  
Rodolfo Rondón ◽  
Claudio Oliveira ◽  
Irani A. Ferreira ◽  
Cesar Martins ◽  
...  
Keyword(s):  
Chromosome Pair ◽  
Chromosome Complement ◽  
Gene Clusters ◽  
Ribosomal Gene ◽  
Nucleolus Organizer ◽  
Rrna Genes ◽  
Single Chromosome ◽  
Nucleolus Organizer Regions ◽  
Robertsonian Rearrangements ◽  
Acrocentric Chromosomes

In the present study, three species of Lutjaninae, Lutjanus analis, L. griseus and L. synagris, were analyzed by conventional Giemsa staining, C-banding and silver staining, to reveal active Nucleolus Organizer Regions (NORs). Fluorescent in situ hybridization (FISH) was also applied to establish the number and location of the ribosomal gene clusters (18S and 5S rRNA genes). Counts of diploid metaphasic cells revealed a diploid modal chromosome complement composed of 48 acrocentric chromosomes in both L. analis and L. griseus. Two cytotypes were observed in L. synagris: cytotype I, with 2n=48 acrocentric chromosomes, found in 19 specimens, and cytotype II, with 46 acrocentric chromosomes and one large metacentric, found in two specimens. The large metacentric, which possibly originated from a Robertsonian rearrangement, was not found to be sex-related. In the three species, constitutive heterochromatin is located in the centromeres of all chromosomes. NORs were detected on the short arms of a single chromosome pair, number 24 in L. analis and number 6 in both cytotypes of L. synagris. In L. griseus, a polymorphism of the NORs number was detected, by both Ag-staining and FISH, as females show a maximum of three NORs, and males a maximum of six NORs. In all species, minor ribosomal genes were found located on a single chromosome pair. The obtained data, along with those previously reported for other five Lutjanidae species, show that a general chromosome homogeneity occurs within the family, but that derived karyotypes based on Robertsonian rearrangements as well as multiple and variable NORs sites can also be found.

scholarly journals The role of chromosomal fusion in the karyotypic evolution of the genus Ageneiosus (Siluriformes: Auchenipteridae)

2013 ◽  
Vol 11 (2) ◽  
pp. 327-334 ◽  
Author(s):  
Roberto Laridondo Lui ◽  
Daniel Rodrigues Blanco ◽  
Juliana de Fatima Martinez ◽  
Vladimir Pavan Margarido ◽  
Paulo Cesar Venere ◽  
...  
Keyword(s):  
Chromosome Pair ◽  
5S Rdna ◽  
Proximal Region ◽  
Terminal Region ◽  
Metacentric Chromosome ◽  
South American ◽  
Submetacentric Chromosome ◽  
Araguaia River ◽  
The Family ◽  
Preferential Location

Ageneiosus is the most widely distributed genus of the family Auchenipteridae among South American river basins. Although chromosome studies in the family are scarce, this genus has the largest number of analyzed species, with 2n = 54 to 56 chromosomes, differing from the rest of the family (2n = 58). This study aimed to analyze Ageneiosus inermis from the Araguaia River basin. The diploid number found was of 56 chromosomes. Heterochromatin was allocated in terminal region of most chromosomes, plus a pericentromeric heterochromatic block in pair 1, a pair distinguished by size in relation to other chromosomes pairs. AgNORs were detected in only one submetacentric chromosome pair, which was confirmed by FISH. 5S rDNA was present in only one metacentric chromosome pair. Hybridization with [TTAGGG]n sequence marked the telomeres of all chromosomes, in addition to an ITS in the proximal region of the short arm of pair 1. The repetitive [GATA]n sequence was dispersed, with preferential location in terminal region of the chromosomes. Ageneiosus has a genomic organization somewhat different when compared to other Auchenipteridae species. Evidences indicate that a chromosomal fusion originated the first metacentric chromosome pair in A. inermis, rearrangement which may be a basal event for the genus

scholarly journals Karyotypic characterization of Prochilodus mariae, Semaprochilodus kneri and S. laticeps(Teleostei: Prochilodontidae) from Caicara del Orinoco, Venezuela

2003 ◽  
Vol 1 (1) ◽  
pp. 47-52 ◽  
Author(s):  
Claudio Oliveira ◽  
Mauro Nirchio ◽  
Ángel Granado ◽  
Sara Levy
Keyword(s):  
Chromosome Number ◽  
Chromosome Pair ◽  
Nucleolus Organizer ◽  
Single Chromosome ◽  
Nucleolus Organizer Regions ◽  
The Family ◽  
Structural Chromosome ◽  
Almost All ◽  
Freshwater Environments

Fish of the family Prochilodontidae are considered one of the most important components of commercial and subsistence fishery in freshwater environments in South America. This family consists of 21 species and three genera. In the present study, the karyotypes of Prochilodus mariae, Semaprochilodus kneri, and S. laticeps from Caicara del Orinoco, Bolivar State, Venezuela were studied. The species P. mariae, S. kneri and S. laticeps exhibited 2n=54 chromosomes (40 metacentric and 14 submetacentric), a single chromosome pair with nucleolus organizer regions, and a large amount of heterochromatin found at centromeric and pericentromeric positions in almost all chromosomes. The P. mariae specimens studied displayed 0 to 3 supernumerary microchromosomes. The data obtained here confirm the conservative nature of the chromosome number and morphology of Prochilodontidae and reinforce the hypothesis that small structural chromosome rearrangements were the main cause of the karyotypic diversification seen in this group.

scholarly journals A study of constitutive heterochromatin and NOR banding in three species of Indian major carps from the State of Haryana, India

2018 ◽  
Vol 10 (2) ◽  
pp. 535-539 ◽  
Author(s):  
Neeru Neeru ◽  
Anita Bhatnagar ◽  
Abhay Singh Yadav
Keyword(s):  
Chromosome Pair ◽  
Constitutive Heterochromatin ◽  
Organizer Region ◽  
Nucleolus Organizer Region ◽  
Chromosomal Evolution ◽  
Nucleolus Organizer ◽  
Catla Catla ◽  
Indian Major Carps ◽  
Cytogenetic Survey ◽  
Pair Number

Cytogenetic survey of fishes becomes increasingly important to establish chromosomal relation between the teleosts, to have a glimpse of the relation between chromosomal evolution and differentiation of vertebrate species. In the present study, Chromosome banding studies was done in three species of carps i.e. Catla catla (Hamilton, 1822), Labeo rohita (Hamilton, 1822) and Cirrhinus mrigala (Hamilton, 1822). Diploid chromosome number 50 was observed in all 3 species of carps. The chromosomes of C. catla, L. rohita and C. mrigala showed constitutive heterochromatin at telomeric and centromeric regions of chromosomes. The Ag-NOR (Argyrophilic-Nucleolus Organizer Region) bands were observed on homologous chromosome pair number 11 in C. catla, 15th chromosome pair in L. rohita. In C. mrigala, the Ag- NOR staining elucidated the presence of darkly stained NORs on the terminal region of the long arms of one of the chromosome. Another homologue of this chromosome pair could not be localized due to scattering of chromosomes. The results depict that variation in ecological conditions with time due to human activities can not only affect the chromosomal number but also chromosomal morphology.  

scholarly journals Karyotype variability in neotropical catfishes of the family Pimelodidae (Teleostei: Siluriformes)

2011 ◽  
Vol 9 (1) ◽  
pp. 97-105 ◽  
Author(s):  
Américo Moraes Neto ◽  
Maelin da Silva ◽  
Daniele Aparecida Matoso ◽  
Marcelo Ricardo Vicari ◽  
Mara Cristina de Almeida ◽  
...  
Keyword(s):  
Fluorescent In Situ Hybridization ◽  
Diploid Number ◽  
Molecular Cytogenetics ◽  
Ribosomal Genes ◽  
Nucleolus Organizer ◽  
Nucleolus Organizer Regions ◽  
Karyotype Variability ◽  
Interspecific Variations ◽  
The Family

Karyotypic data are presented for four species of fish belonging to the Pimelodidae family. These species show a conserved diploid number, 2n = 56 chromosomes, with different karyotypic formulae. The analyzed species showed little amount of heterochromatin located preferentially in the centromeric and telomeric regions of some chromosomes. The nucleolus organizer regions activity (Ag-NORs) and the chromosomal location of ribosomal genes by fluorescent in situ hybridization (FISH), with 18S and 5S probes, showing only one chromosome pair marked bearer of ribosomal genes, the only exception was Pimelodus britskii that presented multiple NORs and syntenic location of the 18S and 5S probes. Non-Robertsonian events, as pericentric inversion and NORs duplication are requested to explain the karyotype diversification in Pseudoplatystoma from the rio Paraguay (MS), Pimelodus from the rio Iguaçu (PR), Sorubim from the rio Paraguay (MS) and Steindachneridion from the rio Paraíba do Sul (SP). The obtained data for the karyotype macrostructure of these species corroborates a conserved pattern observed in Pimelodidae. On the other hand, interspecific variations detected by molecular cytogenetics markers made possible cytotaxonomic inferences and differentiation of the species here analyzed.

scholarly journals Interspecific cytogenetic relationships in three Acestrohynchus species (Acestrohynchinae, Characiformes) reveal the existence of possible cryptic species

2020 ◽  
Vol 14 (1) ◽  
pp. 27-42
Author(s):  
Alber Sousa Campos ◽  
Ramon Marin Favarato ◽  
Eliana Feldberg
Keyword(s):  
Chromosome Pair ◽  
Organizer Region ◽  
Nucleolus Organizer Region ◽  
5S Rdna ◽  
Nucleolus Organizer ◽  
Telomeric Sequences ◽  
Interstitial Telomeric Sequences ◽  
Rdna Sites ◽  
Species Specific

The karyotypes and chromosomal characteristics of three Acestrorhynchus Eigenmann et Kennedy, 1903 species were examined using conventional and molecular protocols. These species had invariably a diploid chromosome number 2n = 50. Acestrorhynchus falcatus (Block, 1794) and Acestrorhynchus falcirostris (Cuvier, 1819) had the karyotype composed of 16 metacentric (m) + 28 submetacentric (sm) + 6 subtelocentric (st) chromosomes while Acestrorhynchus microlepis (Schomburgk, 1841) had the karyotype composed of 14m+30sm+6st elements. In this species, differences of the conventional and molecular markers between the populations of Catalão Lake (AM) and of Apeu Stream (PA) were found. Thus the individuals of Pará (Apeu) were named Acestrorhynchus prope microlepis. The distribution of the constitutive heterochromatin blocks was species-specific, with C-positive bands in the centromeric and telomeric regions of a number of different chromosomes, as well as in interstitial sites and completely heterochromatic arms. The phenotypes of nucleolus organizer region (NOR) were simple, i. e. in a terminal position on the p arm of pair No. 23 except in A. microlepis, in which it was located on the q arm. Fluorescence in situ hybridization (FISH) revealed 18S rDNA sites on one chromosome pair in karyotype of A. falcirostris and A. prope microlepis (pair No. 23) and three pairs (Nos. 12, 23, 24) in A. falcatus and (Nos. 8, 23, 24) in A. microlepis; 5S rDNA sites were detected in one chromosome pair in all three species. The mapping of the telomeric sequences revealed terminal sequences in all the chromosomes, as well as the presence of interstitial telomeric sequences (ITSs) in a number of chromosome pairs. The cytogenetic data recorded in the present study indicate that A. prope microlepis may be an unnamed species.

scholarly journals Differential hypomethylation of the repetitive Tol2/Alu-rich sequences in the genome of Bodianus species (Labriformes, Labridae)

2018 ◽  
Vol 12 (2) ◽  
pp. 145-162 ◽  
Author(s):  
Clóvis C. Motta-Neto ◽  
André Marques ◽  
Gideão W.W.F. Costa ◽  
Marcelo B. Cioffi ◽  
Luiz A.C. Bertollo ◽  
...  
Keyword(s):  
Chromosomal Region ◽  
5S Rdna ◽  
Methylation Pattern ◽  
Metaphase Chromosomes ◽  
Rdna Sites ◽  
The Family ◽  
Secondary Constrictions

Representatives of the order Labriformes show karyotypes of extreme conservatism together with others with high chromosomal diversification. However, the cytological characterization of epigenetic modifications remains unknown for the majority of the species. In the family Labridae, the most abundant fishes on tropical reefs, the genomes of the genus Bodianus Bloch, 1790 have been characterized by the occurrence of a peculiar chromosomal region, here denominated BOD. This region is exceptionally decondensed, heterochromatic, argentophilic, GC-neutral and, in contrast to classical secondary constrictions, shows no signals of hybridization with 18S rDNA probes. In order to characterize the BOD region, the methylation pattern, the distribution of Alu and Tol2 retrotransposons and of 18S and 5S rDNA sites, respectively, were analyzed by Fluorescence In Situ Hybridization (FISH) on metaphase chromosomes of two Bodianus species, B.insularis Gomon & Lubbock, 1980 and B.pulchellus (Poey, 1860). Immunolocalization of the 5-methylcytosine revealed hypermethylated chromosomal regions, dispersed along the entire length of the chromosomes of both species, while the BOD regions exhibited a hypomethylated pattern. Hypomethylation of the BOD region is associated with the precise co-location of Tol2 and Alu elements, suggesting their active participation in the regulatory epigenetic process. This evidence underscores a probable differential methylation action during the cell cycle, as well as the role of Tol2/Alu elements in functional processes of fish genomes.

scholarly journals Ribosomal DNA localization on Lathyrus species chromosomes by FISH

2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Hoda B. M. Ali ◽  
Samira A. Osman
Keyword(s):  
Genome Mapping ◽  
Chromosome Complement ◽  
5S Rdna ◽  
Rdna Locus ◽  
5S Rrna ◽  
Rrna Genes ◽  
45S Rdna ◽  
Metaphase Chromosomes ◽  
Lathyrus Odoratus ◽  
5S Rrna Genes

Abstract Background Fluorescence In Situ Hybridization (FISH) played an essential role to locate the ribosomal RNA genes on the chromosomes that offered a new tool to study the chromosome structure and evolution in plant. The 45S and 5S rRNA genes are independent and localized at one or more loci per the chromosome complement, their positions along chromosomes offer useful markers for chromosome discriminations. In the current study FISH has been performed to locate 45S and 5S rRNA genes on the chromosomes of nine Lathyrus species belong to five different sections, all have chromosome number 2n=14, Lathyrus gorgoni Parl, Lathyrus hirsutus L., Lathyrus amphicarpos L., Lathyrus odoratus L., Lathyrus sphaericus Retz, Lathyrus incospicuus L, Lathyrus paranensis Burkart, Lathyrus nissolia L., and Lathyrus articulates L. Results The revealed loci of 45S and 5S rDNA by FISH on metaphase chromosomes of the examined species were as follow: all of the studied species have one 45S rDNA locus and one 5S rDNA locus except L. odoratus L., L. amphicarpos L. and L. sphaericus Retz L. have two loci of 5S rDNA. Three out of the nine examined species have the loci of 45S and 5S rRNA genes on the opposite arms of the same chromosome (L. nissolia L., L. amphicarpos L., and L. incospicuus L.), while L. hirsutus L. has both loci on the same chromosome arm. The other five species showed the loci of the two types of rDNA on different chromosomes. Conclusion The detected 5S and 45S rDNA loci in Lathyrus could be used as chromosomal markers to discriminate the chromosome pairs of the examined species. FISH could discriminate only one chromosome pair out of the seven pairs in three species, in L. hirsutus L., L. nissolia L. and L. incospicuus L., and two chromosome pairs in five species, in L. paranensis Burkart, L. odoratus L., L. amphicarpos L., L. gorgoni Parl. and L. articulatus L., while it could discriminate three chromosome pairs in L. sphaericus Retz. these results could contribute into the physical genome mapping of Lathyrus species and the evolution of rDNA patterns by FISH in the coming studies in future.

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