scholarly journals Chromosome Banding in Amphibia. XXXII. The Genus Xenopus (Anura, Pipidae)

2015 ◽  
Vol 145 (3-4) ◽  
pp. 201-217 ◽  
Author(s):  
Michael Schmid ◽  
Claus Steinlein
Keyword(s):  
Chromosome Pair ◽  
Repetitive Sequences ◽  
5S Rdna ◽  
Mitotic Chromosomes ◽  
Banding Patterns ◽  
Single Chromosome ◽  
Replication Banding ◽  
Rdna Sequences ◽  
High Degree ◽  
Replication Bands

Mitotic chromosomes of 16 species of the frog genus Xenopus were prepared from kidney and lung cell cultures. In the chromosomes of 7 species, high-resolution replication banding patterns could be induced by treating the cultures with 5-bromodeoxyuridine (BrdU) and deoxythymidine (dT) in succession, and in 6 of these species the BrdU/dT-banded chromosomes could be arranged into karyotypes. In the 3 species of the clade with 2n = 20 and 4n = 40 chromosomes (X. tropicalis, X. epitropicalis, X. new tetraploid 1), as well as in the 3 species with 4n = 36 chromosomes (X. laevis, X. borealis, X. muelleri), the BrdU/dT-banded karyotypes show a high degree of homoeology, though differences were detected between these groups. Translocations, inversions, insertions or sex-specific replication bands were not observed. Minor replication asynchronies found between chromosomes probably involve heterochromatic regions. BrdU/dT replication banding of Xenopus chromosomes provides the landmarks necessary for the exact physical mapping of genes and repetitive sequences. FISH with an X. laevis 5S rDNA probe detected multiple hybridization sites at or near the long-arm telomeric regions in most chromosomes of X. laevis and X. borealis, whereas in X. muelleri, the 5S rDNA sequences are located exclusively at the long-arm telomeres of a single chromosome pair. Staining with the AT base pair-specific fluorochrome quinacrine mustard revealed brightly fluorescing heterochromatic regions in the majority of X. borealis chromosomes which are absent in other Xenopus species.

15N isotope dilution to quantify dinitrogen (N2) fixation associated with Canadian and Brazilian wheat

1983 ◽  
Vol 61 (6) ◽  
pp. 1667-1671 ◽  
Author(s):  
R. J. Rennie ◽  
J. R. deFreitas ◽  
A. P. Ruschel ◽  
P. V. Vose
Keyword(s):  
Isotope Dilution ◽  
Chromosome Pair ◽  
Azospirillum Brasilense ◽  
Triticum Aestivum L ◽  
Dilution Technique ◽  
15N Isotope ◽  
Wheat Varieties ◽  
Single Chromosome ◽  
Total Plant ◽  
High Degree

Putative dinitrogen (N2) fixation associated with wheat (Triticum aestivum L. emend. Thell) has been studied using acetylene reduction and nonisotopic N-balance techniques. Absolute proof of N2 fixation using 15N2 (gas) or 15N isotope dilution procedures has not been reported. This paper presents the first use of the 15N isotope dilution technique to determine in wheat the percent plant N derived from associated N2 fixation. Although inoculation with either Bacillus polymyxa (C-11-25) or Azospirillum brasilense (ATCC 29145) resulted in no significant increase in total plant N in nine Canadian and one Brazilian wheat varieties, isotopic N data showed that N2 fixation did occur. The amounts of plant N derived from atmosphere, fertilizer, and soil varied. A high degree of plant–bacterial specificity existed. In several instances, the substitution of a single chromosome pair in the wheat regulated the amount of N2 fixed. The agreement between this 15N isotope experiment and two previous nonisotopic experiments suggests that the trait supporting N2 fixation in wheat may be consistently expressed in the varietal lines.

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 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.

The Organization of Repetitive DNA in the Genomes of Amazonian Lizard Species in the Family Teiidae

2015 ◽  
Vol 147 (2-3) ◽  
pp. 161-168 ◽  
Author(s):  
Natalia D.M. Carvalho ◽  
Vanessa S.S. Pinheiro ◽  
Edson J. Carmo ◽  
Leonardo G. Goll ◽  
Carlos H. Schneider ◽  
...  
Keyword(s):  
Repetitive Dna ◽  
Dna Sequences ◽  
Genome Organization ◽  
Repetitive Sequences ◽  
5S Rdna ◽  
Distinct Pattern ◽  
Structural Function ◽  
Mitotic Chromosomes ◽  
Lizard Species ◽  
Evolutionary Diversification

Repetitive DNA is the largest fraction of the eukaryote genome and comprises tandem and dispersed sequences. It presents variations in relation to its composition, number of copies, distribution, dynamics, and genome organization, and participates in the evolutionary diversification of different vertebrate species. Repetitive sequences are usually located in the heterochromatin of centromeric and telomeric regions of chromosomes, contributing to chromosomal structures. Therefore, the aim of this study was to physically map repetitive DNA sequences (5S rDNA, telomeric sequences, tropomyosin gene 1, and retroelements Rex1 and SINE) of mitotic chromosomes of Amazonian species of teiids (Ameiva ameiva, Cnemidophorus sp. 1, Kentropyx calcarata, Kentropyx pelviceps, and Tupinambis teguixin) to understand their genome organization and karyotype evolution. The mapping of repetitive sequences revealed a distinct pattern in Cnemidophorus sp. 1, whereas the other species showed all sequences interspersed in the heterochromatic region. Physical mapping of the tropomyosin 1 gene was performed for the first time in lizards and showed that in addition to being functional, this gene has a structural function similar to the mapped repetitive elements as it is located preferentially in centromeric regions and termini of chromosomes.

Distribution of highly repeated DNA sequences in species of the genus Lens Miller

Genome ◽  
2003 ◽  
Vol 46 (6) ◽  
pp. 1118-1124 ◽  
Author(s):  
Incoronata Galasso
Keyword(s):  
Dna Sequences ◽  
Lens Culinaris ◽  
Repetitive Sequences ◽  
5S Rdna ◽  
Chromosome Identification ◽  
Mitotic Chromosomes ◽  
Genomic Relationships ◽  
Lens Nigricans ◽  
25S Rdna

Multiple-target fluorescence in situ hybridization (FISH) was applied on mitotic chromosomes of seven Lens taxa using two highly repetitive sequences (pLc30 and pLc7) isolated from the cultivated lentil and the multigene families for the 18S–5.8S–25S (pTa71) and 5S rRNA (pTa794) from wheat simultaneously as probes. The number and location of pLc30 and pLc7 sites on chromosomes varied markedly among the species, whereas the hybridization pattern of 5S rDNA and 18S–5.8S–25S rDNA was less variable. In general, each species showed a typical FISH karyotype and few differences were observed among accessions belonging to the same species, except for the accessions of Lens odemensis. The most similar FISH karyotype to the cultivated lentil is that of Lens culinaris subsp. orientalis, whereas Lens nigricans and Lens tomentosus are the two species that showed the most divergent FISH patterns compared with all taxa for number and location of pLc30 and 18S–5.8S–25S rDNA sites.Key words: chromosome identification, comparative FISH karyotype, wild Lens species, genomic relationships.

A Tandemly Arranged Pattern of Two 5S rDNA Arrays in Amolops mantzorum (Anura, Ranidae)

2017 ◽  
Vol 151 (3) ◽  
pp. 161-170 ◽  
Author(s):  
Ting Liu ◽  
Menghuan Song ◽  
Yun Xia ◽  
Xiaomao Zeng
Keyword(s):  
Satellite Dna ◽  
Centromeric Region ◽  
5S Rdna ◽  
Type I ◽  
Type Ii ◽  
Mitotic Chromosomes ◽  
Coding Sequences ◽  
Coding Sequence ◽  
Rdna Sequences ◽  
Rdna Organization

In an attempt to extend the knowledge of the 5S rDNA organization in anurans, the 5S rDNA sequences of Amolops mantzorum were isolated, characterized, and mapped by FISH. Two forms of 5S rDNA, type I (209 bp) and type II (about 870 bp), were found in specimens investigated from various populations. Both of them contained a 118-bp coding sequence, readily differentiated by their non-transcribed spacer (NTS) sizes and compositions. Four probes (the 5S rDNA coding sequences, the type I NTS, the type II NTS, and the entire type II 5S rDNA sequences) were respectively labeled with TAMRA or digoxigenin to hybridize with mitotic chromosomes for samples of all localities. It turned out that all probes showed the same signals that appeared in every centromeric region and in the telomeric regions of chromosome 5, without differences within or between populations. Obviously, both type I and type II of the 5S rDNA arrays arranged in tandem, which was contrasting with other frogs or fishes recorded to date. More interestingly, all the probes detected centromeric regions in all karyotypes, suggesting the presence of a satellite DNA family derived from 5S rDNA.

scholarly journals Chromosomal Mapping of Repetitive DNA Sequences in Five Species of Astyanax (Characiformes, Characidae) Reveals Independent Location of U1 and U2 snRNA Sites and Association of U1 snRNA and 5S rDNA

2015 ◽  
Vol 146 (2) ◽  
pp. 144-152 ◽  
Author(s):  
Duilio M.Z.A. Silva ◽  
Ricardo Utsunomia ◽  
José C. Pansonato-Alves ◽  
Cláudio Oliveira ◽  
Fausto Foresti
Keyword(s):  
Repetitive Dna ◽  
Dna Sequences ◽  
Repetitive Sequences ◽  
5S Rdna ◽  
Chromosomal Mapping ◽  
Valid Species ◽  
Small Nuclear Rna ◽  
U2 Snrna ◽  
Rdna Sequences ◽  
U1 Snrna

Astyanax is a genus of Characidae fishes currently composed of 155 valid species. Previous cytogenetic studies revealed high chromosomal diversification among them, and several studies have been performed using traditional cytogenetic techniques to investigate karyotypes and chromosomal locations of 18S and 5S rDNA genes. However, only a few studies are currently available about other repetitive sequences. Here, the chromosomal location of small nuclear RNA genes, identified as U1 and U2 snRNA clusters, was established and compared to the distribution of 5S rDNA and histone clusters in 5 Astyanax species (A. paranae, A. fasciatus, A. bockmanni, A. altiparanae, and A. jordani) using FISH. The cytogenetic mapping of U1 and U2 snRNA demonstrated a conserved pattern in the number of sites per genome independent of the location in Astyanax species. The location of the U1 snRNA gene was frequently associated with 5S rDNA sequences, indicating a possible interaction between the distinct repetitive DNA families. Finally, comparisons involving the location of U1 and U2 snRNA clusters in the chromosomes of Astyanax species revealed a very diverse pattern, suggesting that many rearrangements have occurred during the diversification process of this group.

Karyotype variation in the albino rainbow trout (Oncorhynchus mykiss (Walbaum))

Genome ◽  
2009 ◽  
Vol 52 (4) ◽  
pp. 347-352 ◽  
Author(s):  
K. Ocalewicz ◽  
S. Dobosz
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
X Chromosome ◽  
5S Rdna ◽  
Mitotic Chromosomes ◽  
Dapi Staining ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Rdna Sequences ◽  
Cytogenetic Location

A Robertsonian polymorphism resulting in diploid chromosome number ranging from 59 to 61 and constant chromosome arm number (fundamental number = 104) was observed in the albino rainbow trout ( Oncorhynchus mykiss (Walbaum)) from the yellow color strain. In one individual, 90 mitotic chromosomes and 156 chromosome arms were counted, indicating the fish as a triploid. Morphology of the chromosomes, DAPI staining, and the cytogenetic location of 5S rDNA sequences showed sex-related chromosomal heteromorphism in the specimens. Additionally, length polymorphism of the X chromosome was detected in the studied individuals and two morphs of the X chromosome were described, XL and XS, according to the size of its short arm (p). The XS was observed in the female as well as male albino rainbow trout; however, among females, no XSXS genotype was found. After primed in situ labeling with 5S rDNA primers, the p-arms of both types of the X chromosome showed similar hybridization signals. On the other hand, fluorescence in situ hybridization with telomeric PNA (peptide nucleic acid) probe exhibited weak hybridization spots on the p-arm of the XS chromosome compared with the distinct hybridization spots observed on the XL p-arm. This could reflect a different telomere length on the p-arm of the XS and XL chromosomes. Partial translocation and deletion of the X chromosome p-arm are considered to be responsible for the p-arm length difference between the two morphological variants of X chromosome.

Chromosome banding in salmonid fishes: nucleolar organizer regions in Oncorhynchus

1986 ◽  
Vol 28 (4) ◽  
pp. 502-510 ◽  
Author(s):  
Ruth B. Phillips ◽  
Kerry D. Zajicek ◽  
Fred M. Utter
Keyword(s):  
Chromosome Pair ◽  
Chromosome Banding ◽  
Acrocentric Chromosome ◽  
Nucleolar Organizer ◽  
Nucleolar Organizer Regions ◽  
Salmonid Fishes ◽  
Chromomycin A3 ◽  
Banding Patterns ◽  
Submetacentric Chromosome ◽  
Single Chromosome

Chromosome banding patterns obtained by silver staining and chromomycin a3 (CMA3) staining were analyzed in six species of Oncorhynchus: O. tshawytscha, O. kisutch, O. keta, O. nerka, and O. gorbuscha from North America and O. masou from Japan. Four different chromosomal locations of the nucleolor organizer regions (NORs) were found in different species. In O. tshawytscha, O. kisutch, and O. masou the NORs comprised the entire short arms of one medium-sized acrocentric chromosome pair. In O. nerka the NORs were found in an interstitial band on the short arms of one submetacentric chromosome pair and in O. gorbuscha proximal to the centromere on one metacentric chromosome pair. In O. keta the NORs were found on the telomeres of one small submetacentric chromosome pair. As in the related genera Salmo and Salvelinus chromomycin A3 positive bands were found at the same sites as the AgNORs in all species. Salmonid fish are assumed to be ancestral tetraploids and the considerable differences in chromosome number between different species are thought to be the result of chromosomal fusions after tetraploidization. In all members of the genus Oncorhynchus the rearrangements have resulted in the consolidation of the NORs on a single chromosome pair. The possible significance of intra- and inter-species NOR polymorphisms is discussed.Key words: nucleolar organizer regions, salmon, Oncorhynchus, chromosomes.

scholarly journals Cytogenetic markers using single-sequence probes reveal chromosomal locations of tandemly repetitive genes in scleractinian coral Acropora pruinosa

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Joshua Vacarizas ◽  
Takahiro Taguchi ◽  
Takuma Mezaki ◽  
Masatoshi Okumura ◽  
Rei Kawakami ◽  
...  
Keyword(s):  
5S Rdna ◽  
Chromosome 8 ◽  
Chromosome 1 ◽  
Core Histone ◽  
Small Nuclear Rna ◽  
Banding Patterns ◽  
Rdna Probe ◽  
Rdna Sequences ◽  
Single Sequence

AbstractThe short and similar sized chromosomes of Acropora pose a challenge for karyotyping. Conventional methods, such as staining of heterochromatic regions, provide unclear banding patterns that hamper identification of such chromosomes. In this study, we used short single-sequence probes from tandemly repetitive 5S ribosomal RNA (rRNA) and core histone coding sequences to identify specific chromosomes of Acropora pruinosa. Both the probes produced intense signals in fluorescence in situ hybridization, which distinguished chromosome pairs. The locus of the 5S rDNA probe was on chromosome 5, whereas that of core histone probe was on chromosome 8. The sequence of the 5S rDNA probe was composed largely of U1 and U2 spliceosomal small nuclear RNA (snRNA) genes and their interspacers, flanked by short sequences of the 5S rDNA. This is the first report of a tandemly repetitive linkage of snRNA and 5S rDNA sequences in Cnidaria. Based on the constructed tentative karyogram and whole genome hybridization, the longest chromosome pair (chromosome 1) was heteromorphic. The probes also hybridized effectively with chromosomes of other Acropora species and population, revealing an additional core histone gene locus. We demonstrated the applicability of short-sequence probes as chromosomal markers with potential for use across populations and species of Acropora.

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