A family of centromeric satellite DNAs from the European brown frog Rana graeca italica

Genome ◽  
1997 ◽  
Vol 40 (5) ◽  
pp. 774-781 ◽  
Author(s):  
Daniela Ester Cardone ◽  
Marcello Marotta ◽  
Claudia Rosati ◽  
Gianni Chinali ◽  
Isidoro Feliciello

Digestion of Rana graeca italica DNA with Asp718I produces highly repetitive fragments of 281 and 385 bp that were cloned and sequenced. The shorter fragment corresponds to the unit repeat (RgiS1b) of a satellite DNA. The longer fragment was found to be part of a 494-bp repeat of another satellite DNA (RgiS1a) that was cloned intact as an EcoRV fragment. RgiS1b is 97% homologous to RgiS1a, from which it seems to be derived by a single deletion. Among all species tested, only the related brown frog Rana dalmatina contained homologous repetitive DNA. The overall number of RgiS1a and RgiS1b repeats per R. graeca italica haploid genome was estimated to be 2.7 × 105. RgiS1a and RgiS1b repeats are organized in separate arrays, but repetitive units formed by various combinations of the two repeats were also observed on Southern blots. The amount of these extra repeats varies greatly among animals from the same population, representing a rare case of individual variability in the satellite DNA organization. FISH with probes specific for both satellites, or for RgiS1a only, labeled the centromeric and pericentromeric heterochromatin of all chromosomes. This indicated that RgiS1a and RgiS1b are interspersed within the same heterochromatic regions of the chromosomes.Key words: satellite DNA, nucleotide sequence analysis, tandem repeats organization, amphibian chromosomes.

Genome ◽  
1998 ◽  
Vol 41 (2) ◽  
pp. 148-153 ◽  
Author(s):  
Monique Abadon ◽  
Eric Grenier ◽  
Christian Laumond ◽  
Pierre Abad

An AluI satellite DNA family has been cloned from the entomopathogenic nematode Heterorhabditis indicus. This repeated sequence appears to be an unusually abundant satellite DNA, since it constitutes about 45% of the H. indicus genome. The consensus sequence is 174 nucleotides long and has an A + T content of 56%, with the presence of direct and inverted repeat clusters. DNA sequence data reveal that monomers are quite homogeneous. Such homogeneity suggests that some mechanism is acting to maintain the homogeneity of this satellite DNA, despite its abundance, or that this repeated sequence could have appeared recently in the genome of H. indicus. Hybridization analysis of genomic DNAs from different Heterorhabditis species shows that this satellite DNA sequence is specific to the H. indicus genome. Considering the species specificity and the high copy number of this AluI satellite DNA sequence, it could provide a rapid and powerful tool for identifying H. indicus strains.Key words: AluI repeated DNA, tandem repeats, species-specific sequence, nucleotide sequence analysis.


Genes ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 352 ◽  
Author(s):  
Karen H. Miga

The central goal of medical genomics is to understand the inherited basis of sequence variation that underlies human physiology, evolution, and disease. Functional association studies currently ignore millions of bases that span each centromeric region and acrocentric short arm. These regions are enriched in long arrays of tandem repeats, or satellite DNAs, that are known to vary extensively in copy number and repeat structure in the human population. Satellite sequence variation in the human genome is often so large that it is detected cytogenetically, yet due to the lack of a reference assembly and informatics tools to measure this variability, contemporary high-resolution disease association studies are unable to detect causal variants in these regions. Nevertheless, recently uncovered associations between satellite DNA variation and human disease support that these regions present a substantial and biologically important fraction of human sequence variation. Therefore, there is a pressing and unmet need to detect and incorporate this uncharacterized sequence variation into broad studies of human evolution and medical genomics. Here I discuss the current knowledge of satellite DNA variation in the human genome, focusing on centromeric satellites and their potential implications for disease.


2021 ◽  
Vol 22 (9) ◽  
pp. 4309
Author(s):  
Jitendra Thakur ◽  
Jenika Packiaraj ◽  
Steven Henikoff

Satellite DNA consists of abundant tandem repeats that play important roles in cellular processes, including chromosome segregation, genome organization and chromosome end protection. Most satellite DNA repeat units are either of nucleosomal length or 5–10 bp long and occupy centromeric, pericentromeric or telomeric regions. Due to high repetitiveness, satellite DNA sequences have largely been absent from genome assemblies. Although few conserved satellite-specific sequence motifs have been identified, DNA curvature, dyad symmetries and inverted repeats are features of various satellite DNAs in several organisms. Satellite DNA sequences are either embedded in highly compact gene-poor heterochromatin or specialized chromatin that is distinct from euchromatin. Nevertheless, some satellite DNAs are transcribed into non-coding RNAs that may play important roles in satellite DNA function. Intriguingly, satellite DNAs are among the most rapidly evolving genomic elements, such that a large fraction is species-specific in most organisms. Here we describe the different classes of satellite DNA sequences, their satellite-specific chromatin features, and how these features may contribute to satellite DNA biology and evolution. We also discuss how the evolution of functional satellite DNA classes may contribute to speciation in plants and animals.


Genetics ◽  
1994 ◽  
Vol 136 (1) ◽  
pp. 333-341
Author(s):  
W Stephan ◽  
S Cho

Abstract A simulation model of sequence-dependent amplification, unequal crossing over and mutation is analyzed. This model predicts the spontaneous formation of tandem-repetitive patterns of noncoding DNA from arbitrary sequences for a wide range of parameter values. Natural selection is found to play an essential role in this self-organizing process. Natural selection which is modeled as a mechanism for controlling the length of a nucleotide string but not the sequence itself favors the formation of tandem-repetitive structures. Two measures of sequence heterogeneity, inter-repeat variability and repeat length, are analyzed in detail. For fixed mutation rate, both inter-repeat variability and repeat length are found to increase with decreasing rates of (unequal) crossing over. The results are compared with data on micro-, mini- and satellite DNAs. The properties of minisatellites and satellite DNAs resemble the simulated structures very closely. This suggests that unequal crossing over is a dominant long-range ordering force which keeps these arrays homogeneous even in regions of very low recombination rates, such as at satellite DNA loci. Our analysis also indicates that in regions of low rates of (unequal) crossing over, inter-repeat variability is maintained at a low level at the expense of much larger repeat units (multimeric repeats), which are characteristic of satellite DNA. In contrast, the microsatellite data do not fit the proposed model well, suggesting that unequal crossing over does not act on these very short tandem arrays.


Author(s):  
Philippe Castagnone-Sereno

Abstract This chapter provides an overview of the practical methodologies that can be used to identify and characterize the tandem repeats that are most frequently used as genetic markers in nematodes (including plant-parasitic and entomopathogenic nematodes), namely satellite DNA and microsatellites. The objective is not to provide turnkey protocols, but rather to return to the main principles that govern these protocols. Case studies on nematodes will serve to illustrate the point. In that respect, two well-defined situations are to be considered, depending on whether genomic resources for the species under investigation are available or not.


Genome ◽  
1999 ◽  
Vol 42 (5) ◽  
pp. 881-886 ◽  
Author(s):  
P Lorite ◽  
MF García ◽  
T Palomeque

This paper is the first record of the satellite DNA of Formicidae. The satellite DNA of the ant Messor structor is organized in a tandem repeat of monomers of 79 bp. Like satellite DNAs of other insects, it is AT rich and presents direct and inverted internal repeats. Restriction analysis of the total DNA with methylation-sensitive enzymes strongly suggests that this DNA is undermethylated. The presence of this repetitive DNA in other species of the genus Messor is also tested. Key words: Formicidae, methylation, nucleotide DNA composition, satellite DNA.


Insects ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 306 ◽  
Author(s):  
Pablo Mora ◽  
Jesús Vela ◽  
Areli Ruiz-Mena ◽  
Teresa Palomeque ◽  
Pedro Lorite

Ladybird beetles (Coccinellidae) are one of the largest groups of beetles. Among them, some species are of economic interest since they can act as a biological control for some agricultural pests whereas other species are phytophagous and can damage crops. Chnootriba argus (Coccinellidae, Epilachnini) has large heterochromatic pericentromeric blocks on all chromosomes, including both sexual chromosomes. Classical digestion of total genomic DNA using restriction endonucleases failed to find the satellite DNA located on these heterochromatic regions. Cloning of C0t-1 DNA resulted in the isolation of a repetitive DNA with a repeat unit of six base pairs, TTAAAA. The amount of TTAAAA repeat in the C. argus genome was about 20%. Fluorescence in situ hybridization (FISH) analysis and digestion of chromosomes with the endonuclease Tru9I revealed that this repetitive DNA could be considered as the putative pericentromeric satellite DNA (satDNA) in this species. The presence of this satellite DNA was tested in other species of the tribe Epilachnini and it is also present in Epilachna paenulata. In both species, the TTAAAA repeat seems to be the main satellite DNA and it is located on the pericentromeric region on all chromosomes. The size of this satDNA, which has only six base pairs is unusual in Coleoptera satellite DNAs, where satDNAs usually have repeat units of a much larger size. Southern hybridization and FISH proved that this satDNA is conserved in some Epilachnini species but not in others. This result is in concordance with the controversial phylogenetic relationships among the genera of the tribe Epilachnini, where the limits between genera are unclear.


1989 ◽  
Vol 10 (4) ◽  
pp. 387-396 ◽  
Author(s):  
Gaetano Odierna

AbstractThis study investigates the karyotypes, genome sizc, constitutive heterochromatin, and NOR localization in three European brown frog species: Rana iberica, R. dalmatina and R. graeca. The three species all possess a karyotype of 26 chromosomes. The genome size is respectively 6.9, 9.7 and 11.3 pg/N in R. iberica, R. dalmatina and R. graeca. Constitutive heterochromatin is 1.7% in R. iberica, 3.1 % in R. dalmatina and 7.0% in R. graeca. The NOR is located on the long arm of the 10th chromosome in R. iberica and R. graeca, whereas it is pericentromerically localized on the short arm of the 3rd chromosome in R. dalmatina. A single NOR extrasite is found in R. graeca. Results suggest that European brown frogs have evolved independently from North American and Asian groups. Moreover, the variation observed in constitutive heterochromatin is informative of different amplification levels of satellite-like DNA. Data also suggest that in R. dalmatina NOR localization on the 3rd chromosome may be derivcd by amplification of a pre-existing NOR site.


1995 ◽  
Vol 71 (4) ◽  
pp. 345-351 ◽  
Author(s):  
M.A. Garrido-Ramos ◽  
M. Jamilena ◽  
R. Lozano ◽  
Ruiz Rejón ◽  
Ruiz Rejón

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