Advances in the cytogenetics of Annonaceae, the case of Annona cherimola L.

Genome ◽  
2020 ◽  
Vol 63 (7) ◽  
pp. 357-364
Author(s):  
Egizia Falistocco ◽  
Nicoletta Ferradini
Keyword(s):  
Dna Sequences ◽  
5S Rdna ◽  
Principal Component ◽  
Centromeric Heterochromatin ◽  
Fluorochrome Banding ◽  
Important Species ◽  
Annona Cherimola ◽  
Rdna Sites ◽  
Basic Reference ◽  
Dapi Banding

Annonaceae represent the largest extant family among the early divergent angiosperms. Despite the long-standing interest in its evolutionary and taxonomic aspects, cytogenetic studies on this family remain extremely few even on economically important species. With this study, we realized a detailed characterization of the chromosomes of Annona cherimola (2n = 14) by a combination of in situ hybridization techniques, fluorochrome banding, and karyomorphological analysis. FISH revealed that 45S and 5S rDNA sites are co-localized in correspondence to the secondary constrictions of the SAT-chromosome pair. Some hypotheses on the organization of the linked 45S and 5S rDNA repeats have been made. FISH with Arabidopsis-type telomeric arrays demonstrated that the A. cherimola telomeres are constituted by TTTAGGG sequences and that they are exclusively localized at the extremities of chromosomes. An insight into the chromosome structure of A. cherimola was obtained by the self-GISH procedure which revealed highly repeated DNA sequences localized in the centromeric regions of all chromosomes. The correspondence of s-GISH signals with DAPI banding suggests that these sequences are the principal component of the centromeric heterochromatin of this species. The karyotype of A. cherimola here described is proposed as the basic reference karyotype for successive investigations in Annonaceae.

scholarly journals Composition and Nature of Heterochromatin in the Electrical Fish (Knifefishes) Gymnotus (Gymnotiformes: Gymnotidae)

2021 ◽  
Author(s):  
Maelin da Silva ◽  
Daniele Aparecida Matoso ◽  
Vladimir Pavan Margarido ◽  
Eliana Feldberg ◽  
Roberto Ferreira Artoni
Keyword(s):  
Dna Sequences ◽  
5S Rdna ◽  
Chromosome Mapping ◽  
South American ◽  
Sequence Specificity ◽  
Satellite Sequences ◽  
Rdna Sites ◽  
Close Relationship ◽  
Heterochromatic Sequence ◽  
South American Continent

Fishes of the genus Gymnotus have been suggested as a good model for biogeographic studies in the South American continent. In relation to heterochromatin, species of this genus have blocks preferably distributed in the centromeric region. The content of these regions has been shown to be variable, with description of transposable elements, pseudogenes of 5S rDNA and satellite sequences. In G. carapo Clade, although geographically separated, species with 2n = 54 chromosomes share the distribution of many 5S rDNA sites, a unique case within the genus. Here, repetitive DNA sequences from G. sylvius (2n = 40) and G. paraguensis (2n = 54) were isolated and mapped to understand their constitution. The chromosome mapping by FISH showed an exclusive association in the centromeres of all chromosomes. However, the cross-FISH did not show positive signs of interspecific hybridization, indicating high levels of heterochromatic sequence specificity. In addition, COI-1 sequences were analyzed in some species of Gymnotus, which revealed a close relationship between species of clade 2n = 54, which have multiple 5S rDNA sites. Possibly, the insertion of retroelements or pseudogenization and dispersion of this sequence occurred before the geographic dispersion of the ancestor of this clade from the Amazon region to the hydrographic systems of Paraná-Paraguay, a synapomorphy for the group.

scholarly journals Distress Regulates Different Pathways in the Brain of Common Carp: A Preliminary Study

Animals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 585
Author(s):  
Alexander Burren ◽  
Constanze Pietsch
Keyword(s):  
Gene Regulation ◽  
Common Carp ◽  
Binding Protein ◽  
Principal Component ◽  
Brain Regions ◽  
Point Estimation ◽  
Early Gene ◽  
Important Species ◽  
Preliminary Study ◽  
The Brain

In this study, a stress trial was conducted with common carp, one of the most important species in aquaculture worldwide, to identify relevant gene regulation pathways in different areas of the brain. Acute distress due to exposure to air significantly activated the expression of the immediate early gene c-fos in the telencephalon. In addition, evidence for regulation of the two corticotropin-releasing factor (crf) genes in relation to their binding protein (corticotropin-releasing hormone-binding protein, crh-bp) is presented in this preliminary study. Inferences on the effects of due to exposure to air were obtained by using point estimation, which allows the prediction of a single value. This constitutes the best description to date of the previously generally unknown effects of stress in different brain regions in carp. Furthermore, principal component analyses were performed to reveal possible regulation patterns in the different regions of the fish brain. In conclusion, these preliminary studies on gene regulation in the carp brain that has been influenced by exposure to a stressor reveal that a number of genes may be successfully used as markers for exposure to unfavourable conditions.

Effects of the diploidisation process upon the 5S and 35S rDNA sequences in the allopolyploid species of the Dilatata group of Paspalum (Poaceae, Paniceae)

2019 ◽  
Vol 67 (7) ◽  
pp. 521
Author(s):  
Magdalena Vaio ◽  
Cristina Mazzella ◽  
Marcelo Guerra ◽  
Pablo Speranza
Keyword(s):  
Evolutionary Dynamics ◽  
In Situ Hybridisation ◽  
5S Rdna ◽  
Its Region ◽  
Variable Number ◽  
Rrna Genes ◽  
Fluorescence In Situ Hybridisation ◽  
Rdna Sites ◽  
35S Rdna ◽  
Genome Restructuring

The Dilatata group of Paspalum includes species and biotypes native to temperate South America. Among them, five sexual allotetraploids (x = 10) share the same IIJJ genome formula: P. urvillei Steud, P. dasypleurum Kunze ex Desv., P. dilatatum subsp. flavescens Roseng., B.R. Arrill. & Izag., and two biotypes P. dilatatum Vacaria and P. dilatatum Virasoro. Previous studies suggested P. intermedium Munro ex Morong & Britton and P. juergensii Hack. or related species as their putative progenitors and donors of the I and J genome, respectively, and pointed to a narrow genetic base for their maternal origin. It has not yet been established whether the various members of the Dilatata group are the result of a single or of multiple allopolyploid formations. Here, we aimed to study the evolutionary dynamics of rRNA genes after allopolyploidisation in the Dilatata group of Paspalum and shed some light into the genome restructuring of the tetraploid taxa with the same genome formula. We used double target fluorescence in situ hybridisation of 35S and 5S rDNA probes and sequenced the nrDNA internal transcribed spacer (ITS) region. A variable number of loci at the chromosome ends were observed for the 35S rDNA, from 2 to 6, suggesting gain and loss of sites. For the 5S rDNA, only one centromeric pair of signals was observed, indicating a remarkable loss after polyploidisation. All ITS sequences generated were near identical to the one found for P. intermedium. Although sequences showed a directional homogeneisation towards the putative paternal progenitor in all tetraploid species, the observed differences in the number and loss of rDNA sites suggest independent ongoing diploidisation processes in all taxa and genome restructuring following polyploidy.

Molecular evolution of homologous gene sequences in germline-limited and somatic chromosomes of Acricotopus

Genome ◽  
2004 ◽  
Vol 47 (4) ◽  
pp. 732-741 ◽  
Author(s):  
Wolfgang Staiber
Keyword(s):  
Molecular Evolution ◽  
Dna Sequences ◽  
Sequence Data ◽  
Structural Evolution ◽  
5S Rdna ◽  
Oligonucleotide Primer ◽  
Homologous Gene ◽  
Gene Sequences ◽  
Nucleotide Substitutions ◽  
Degenerate Oligonucleotide

The origin of germline-limited chromosomes (Ks) as descendants of somatic chromosomes (Ss) and their structural evolution was recently elucidated in the chironomid Acricotopus. The Ks consist of large S-homologous sections and of heterochromatic segments containing germline-specific, highly repetitive DNA sequences. Less is known about the molecular evolution and features of the sequences in the S-homologous K sections. More information about this was received by comparing homologous gene sequences of Ks and Ss. Genes for 5.8S, 18S, 28S, and 5S ribosomal RNA were choosen for the comparison and therefore isolated first by PCR from somatic DNA of Acricotopus and sequenced. Specific K DNA was collected by microdissection of monopolar moving K complements from differential gonial mitoses and was then amplified by degenerate oligonucleotide primer (DOP)-PCR. With the sequence data of the somatic rDNAs, the homologous 5.8S and 5S rDNA sequences were isolated by PCR from the DOP-PCR sequence pool of the Ks. In addition, a number of K DOP-PCR sequences were directly cloned and analysed. One K clone contained a section of a putative N-acetyltransferase gene. Compared with its homolog from the Ss, the sequence exhibited few nucleotide substitutions (99.2% sequence identity). The same was true for the 5.8S and 5S sequences from Ss and Ks (97.5%–100% identity). This supports the idea that the S-homologous K sequences may be conserved and do not evolve independently from their somatic homologs. Possible mechanisms effecting such conservation of S-derived sequences in the Ks are discussed.Key words: microdissection, DOP-PCR, germline-limited chromosomes, molecular evolution.

Genetic and geographic origin of domesticated peanut as evidenced by 5S rDNA and chloroplast DNA sequences

2012 ◽  
Vol 298 (6) ◽  
pp. 1151-1165 ◽  
Author(s):  
Marina Grabiele ◽  
Laura Chalup ◽  
Germán Robledo ◽  
Guillermo Seijo
Keyword(s):  
Chloroplast Dna ◽  
Dna Sequences ◽  
Geographic Origin ◽  
5S Rdna ◽  
Chloroplast Dna Sequences

Gene mapping of 5S rDNA sites in eight fish species from the Paraíba do Sul river basin, Brazil

2004 ◽  
Vol 106 (1) ◽  
pp. 107-110 ◽  
Author(s):  
K.F. Kavalco ◽  
R. Pazza ◽  
L.A.C. Bertollo ◽  
O. Moreira-Filho
Keyword(s):  
Gene Mapping ◽  
River Basin ◽  
Fish Species ◽  
5S Rdna ◽  
Rdna Sites ◽  
Paraíba Do Sul River

scholarly journals Repetitive DNA sequences accelerate molecular cytogenetic research in plants with small chromosomes

2019 ◽  
Vol 24 (2) ◽  
pp. 82
Author(s):  
Agus Budi Setiawan ◽  
Ari Wibowo ◽  
Chee How Teo ◽  
Shinji Kikuchi ◽  
Takato Koba
Keyword(s):  
Repetitive Dna ◽  
Dna Sequences ◽  
5S Rdna ◽  
Repetitive Dna Sequences ◽  
Type I ◽  
Chromosome Identification ◽  
Metaphase Chromosomes ◽  
Homologous Chromosomes ◽  
Centromeric Sequence ◽  
Subtelomeric Sequence

Repetitive DNA sequences are highly abundant in plant genomes and are favorable probes for chromosome identification in plants. However, it is difficult to conduct studies on the details of metaphase chromosome structures in plants with small chromosomes due to their highly condensed status. Therefore, identification of homologous chromosomes for karyotyping and analyzing chromosome structures is a challenging issue for cytogeneticists without specific probes and precise chromosome stages. In this study, five repetitive DNA probes, i.e., 5S and 45S ribosomal DNAs (rDNAs), melon centromeric sequence (Cmcent), cucumber subtelomeric sequence (Type I), and microsatellite (CT)10 repeats, were used to identify primary constrictions and homologous chromosomes for karyotyping. Four and two loci of 45S rDNA were respectively observed on metaphase and pachytene chromosomes of Abelia × grandiflora. Cmcent was detected on both primary constrictions of melon pachytene and metaphase chromosomes. Furthermore, one pair of 5S rDNA signals were hybridized on melon metaphase chromosomes. Eight and two loci of 45S and 5S rDNA were respectively detected on cucumber chromosomes. Type I and (CT)10 probes were specifically hybridized on subtelomeric and interstitial regions on the chromosomes, respectively. These results suggest that repetitive DNA sequences are versatile probes for chromosome identification in plants with small chromosomes, particularly for karyotyping analyses.

Evolution of Bird Sex Chromosomes Narrated by Repetitive Sequences: Unusual W Chromosome Enlargement in Gallinula melanops (Aves: Gruiformes: Rallidae)

2019 ◽  
Vol 158 (3) ◽  
pp. 152-159 ◽  
Author(s):  
Ricardo J. Gunski ◽  
Rafael Kretschmer ◽  
Marcelo Santos de Souza ◽  
Ivanete de Oliveira Furo ◽  
Suziane A. Barcellos ◽  
...  
Keyword(s):  
Sex Chromosomes ◽  
18S Rdna ◽  
Organizer Region ◽  
Repetitive Sequences ◽  
Nucleolar Organizer Region ◽  
Molecular Cytogenetics ◽  
5S Rdna ◽  
Nucleolar Organizer ◽  
W Chromosome ◽  
Rdna Sites

Among birds, species with the ZZ/ZW sex determination system generally show significant differences in morphology and size between the Z and W chromosomes (with the W usually being smaller than the Z). In the present study, we report for the first time the karyotype of the spot-flanked gallinule (Gallinula melanops) by means of classical and molecular cytogenetics. The spot-flanked gallinule has 2n = 80 (11 pairs of macrochromosomes and 29 pairs of microchromosomes) with an unusual W chromosome that is larger than the Z. Besides being totally heterochromatic, it has a secondary constriction in its long arm corresponding to the nucleolar organizer region, as confirmed by both silver staining and mapping of 18S rDNA probes. This is an unprecedented fact among birds. Additionally, 18S rDNA sites were also observed in 6 microchromosomes, while 5S rDNA was found in just 1 microchromosomal pair. Seven out of the 11 used microsatellite sequences were found to be accumulated in microchromosomes, and 6 microsatellite sequences were found in the W chromosome. In addition to the involvement of heterochromatin and repetitive DNAs in the differentiation of the large W chromosome, the results also show an alternative scenario that highlights the plasticity that shapes the evolutionary history of bird sex chromosomes.

Variation in highly repetitive DNA composition of heterochromatin in rye studied by fluorescence in situ hybridization

Genome ◽  
1995 ◽  
Vol 38 (6) ◽  
pp. 1061-1069 ◽  
Author(s):  
A. Cuadrado ◽  
N. Jouve ◽  
C. Ceoloni
Keyword(s):  
In Situ Hybridization ◽  
Fluorescence In Situ Hybridization ◽  
Repetitive Dna ◽  
Dna Sequences ◽  
5S Rdna ◽  
Individual Identification ◽  
Highly Repetitive Dna ◽  
The Individual

The molecular characterization of heterochromatin in six lines of rye has been performed using fluorescence in situ hybridization (FISH). The highly repetitive rye DNA sequences pSc 119.2, pSc74, and pSc34, and the probes pTa71 and pSc794 containing the 25S–5.8S–18S rDNA (NOR) and the 5S rDNA multigene families, respectively, were used. This allowed the individual identification of all seven rye chromosomes and most chromosome arms in all lines. All varieties showed similar but not identical patterns. A standard in situ hybridization map was constructed following the nomenclature system recommended for C-bands. All FISH sites observed appeared to correspond well with C-band locations, but not all C-banding sites coincided with hybridization sites of the repetitive DNA probes used. Quantitative and qualitative differences between different varieties were found for in situ hybridization response at corresponding sites. Variation between plants and even between homologous chromosomes of the same plant was found in open-pollinated lines. In inbred lines, the in situ pattern of the homologues was practically identical and no variation between plants was detected. The observed quantitative and qualitative differences are consistent with a corresponding variation for C-bands detected both within and between cultivars.Key words: fluorescence in situ hybridization, repetitive DNA, rye, Secale cereale, polymorphism.

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