scholarly journals Characterization of repetitive DNA regions and methylated DNA in ascovirus genomes

2000 ◽  
Vol 81 (12) ◽  
pp. 3073-3082 ◽  
Author(s):  
Yves Bigot ◽  
Karine Stasiak ◽  
Florence Rouleux-Bonnin ◽  
Brian A. Federici
Keyword(s):  
Repetitive Dna ◽  
Evolutionary Relationship ◽  
Phylogenetic Study ◽  
Dna Repeats ◽  
Dna Viruses ◽  
Diadromus Pulchellus ◽  
Fundamental Information ◽  
Close Relationship ◽  
Interspersed Repeats ◽  
Type 3

The accompanying phylogenetic study of large double-stranded DNA viruses based on their δ DNA polymerase genes suggests that ascoviruses (family Ascoviridae) and iridoviruses (family Iridoviridae) are closely related and may share a common ancestor. This relationship was unexpected because of marked differences between these viruses. Iridoviruses produce icosahedral virions and occur broadly among vertebrates and invertebrates, whereas ascoviruses typically produce reniform or bacilliform virions and are restricted to insect hosts, primarily lepidopterans. Detailed comparisons of these two virus types are not possible because fundamental information on the properties of the virions and their genomes is lacking, especially for ascoviruses. To facilitate further investigation of the putative evolutionary relationship between ascoviruses and iridoviruses, the genomes of representative viruses from each family were compared with respect to physical configuration, presence of DNA repeats and degree of DNA methylation. Genomes from Spodoptera frugiperda (SfAV1), Heliothis virescens (HvAV3) and Diadromus pulchellus (DpAV4) ascoviruses were all found to be circular and partially superhelical and to contain large interspersed repeats of 1–3 kbp. Mosquito (IV type 3), lepidopteran (IV type 6) and isopod (IV type 31) iridovirus genomes were all linear and lacked large regions of repetitive DNA. Ascovirus and iridovirus genomes were methylated and one, DpAV4, had the highest degree of methylation of any reported animal DNA virus. The major differences in the physical and biochemical characteristics of ascoviruses and iridoviruses reported here provide a foundation for further studies of their relatedness while making their possible close relationship and divergence during evolution of even greater interest.

scholarly journals Multicluster nosocomial outbreak of parainfluenza virus type 3 infection in a pediatric oncohematology unit: a phylogenetic study

Haematologica ◽  
2009 ◽  
Vol 94 (6) ◽  
pp. 833-839 ◽  
Author(s):  
A. Piralla ◽  
E. Percivalle ◽  
A. Di Cesare-Merlone ◽  
F. Locatelli ◽  
G. Gerna
Keyword(s):  
Virus Type ◽  
Parainfluenza Virus ◽  
Phylogenetic Study ◽  
Nosocomial Outbreak ◽  
Type 3

Highly Condensed Potato Pericentromeric Heterochromatin Contains rDNA-Related Tandem Repeats

Genetics ◽  
2002 ◽  
Vol 162 (3) ◽  
pp. 1435-1444 ◽  
Author(s):  
Robert M Stupar ◽  
Junqi Song ◽  
Ahmet L Tek ◽  
Zhukuan Cheng ◽  
Fenggao Dong ◽  
...  
Keyword(s):  
Repetitive Dna ◽  
Dna Sequences ◽  
Tandem Repeats ◽  
Intergenic Spacer ◽  
Pericentromeric Heterochromatin ◽  
Dna Repeats ◽  
Solanum Bulbocastanum ◽  
Origin And Evolution ◽  
Potato Genome ◽  
Dna Elements

Abstract The heterochromatin in eukaryotic genomes represents gene-poor regions and contains highly repetitive DNA sequences. The origin and evolution of DNA sequences in the heterochromatic regions are poorly understood. Here we report a unique class of pericentromeric heterochromatin consisting of DNA sequences highly homologous to the intergenic spacer (IGS) of the 18S•25S ribosomal RNA genes in potato. A 5.9-kb tandem repeat, named 2D8, was isolated from a diploid potato species Solanum bulbocastanum. Sequence analysis indicates that the 2D8 repeat is related to the IGS of potato rDNA. This repeat is associated with highly condensed pericentromeric heterochromatin at several hemizygous loci. The 2D8 repeat is highly variable in structure and copy number throughout the Solanum genus, suggesting that it is evolutionarily dynamic. Additional IGS-related repetitive DNA elements were also identified in the potato genome. The possible mechanism of the origin and evolution of the IGS-related repeats is discussed. We demonstrate that potato serves as an interesting model for studying repetitive DNA families because it is propagated vegetatively, thus minimizing the meiotic mechanisms that can remove novel DNA repeats.

scholarly journals Structures and stability of simple DNA repeats from bacteria

2020 ◽  
Vol 477 (2) ◽  
pp. 325-339 ◽  
Author(s):  
Vaclav Brazda ◽  
Miroslav Fojta ◽  
Richard P. Bowater
Keyword(s):  
Repetitive Dna ◽  
Dna Sequences ◽  
Genetic Instability ◽  
Repetitive Sequences ◽  
Biological Significance ◽  
Human Diseases ◽  
Repetitive Dna Sequences ◽  
Dna Repeats ◽  
Diverse Range ◽  
Dna Structures

DNA is a fundamentally important molecule for all cellular organisms due to its biological role as the store of hereditary, genetic information. On the one hand, genomic DNA is very stable, both in chemical and biological contexts, and this assists its genetic functions. On the other hand, it is also a dynamic molecule, and constant changes in its structure and sequence drive many biological processes, including adaptation and evolution of organisms. DNA genomes contain significant amounts of repetitive sequences, which have divergent functions in the complex processes that involve DNA, including replication, recombination, repair, and transcription. Through their involvement in these processes, repetitive DNA sequences influence the genetic instability and evolution of DNA molecules and they are located non-randomly in all genomes. Mechanisms that influence such genetic instability have been studied in many organisms, including within human genomes where they are linked to various human diseases. Here, we review our understanding of short, simple DNA repeats across a diverse range of bacteria, comparing the prevalence of repetitive DNA sequences in different genomes. We describe the range of DNA structures that have been observed in such repeats, focusing on their propensity to form local, non-B-DNA structures. Finally, we discuss the biological significance of such unusual DNA structures and relate this to studies where the impacts of DNA metabolism on genetic stability are linked to human diseases. Overall, we show that simple DNA repeats in bacteria serve as excellent and tractable experimental models for biochemical studies of their cellular functions and influences.

Description of new chiactine-bearing sponges provides insights into the higher classification of Calcaronea (Porifera: Calcarea)

Zootaxa ◽  
2019 ◽  
Vol 4615 (2) ◽  
pp. 201
Author(s):  
ADRIANA ALVIZU ◽  
JOANA R. XAVIER ◽  
HANS TORE RAPP
Keyword(s):  
New Species ◽  
Phylogenetic Reconstruction ◽  
Molecular Data ◽  
Phylogenetic Study ◽  
Two New Species ◽  
Close Relationship ◽  
New Material ◽  
Relationship Of ◽  
The Antarctic

A recent phylogenetic study revealed a close relationship between chiactine-bearing (family Achramorphidae, order Leucosolenida) and pugiole-bearing (order Baerida) calcaronean sponges as well as new putative taxa within Achramorphidae. In this study, we present a revision of chiactine-bearing sponges based on morphological re-examination of type material and recently collected specimens, in addition to new molecular data for the ribosomal 18S and C-region of the 28S. We provide re-descriptions for all known chiactine-bearing species, and further describe two new species from the Antarctic (Achramorpha antarctica sp. nov. and Megapogon schiaparellii sp. nov.) and two new species and a new genus from the Nordic Seas (Achramorpha ingolfi sp. nov. and Sarsinella karasikensis gen. nov. sp. nov.). The new phylogenetic reconstruction based on ribosomal 18S and C-region of the 28S confirms previous findings about the close relationship of some members of Baerida and the family Achramorphidae of the order Leucosolenida. However, new material and the addition of molecular data from the type species of both taxa would be required to formally propose changes at (sub-)ordinal levels within the classification of Calcaronean sponges. 

scholarly journals Conversion of DNA Sequences: From a Transposable Element to a Tandem Repeat or to a Gene

Genes ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 1014 ◽  
Author(s):  
Ana Paço ◽  
Renata Freitas ◽  
Ana Vieira-da-Silva
Keyword(s):  
Repetitive Dna ◽  
Dna Sequences ◽  
Tandem Repeats ◽  
Evolutionary Relationship ◽  
Repetitive Dna Sequences ◽  
Dna Remodeling ◽  
Eukaryotic Genomes ◽  
Similar Organization ◽  
Dispersed Repeats

Eukaryotic genomes are rich in repetitive DNA sequences grouped in two classes regarding their genomic organization: tandem repeats and dispersed repeats. In tandem repeats, copies of a short DNA sequence are positioned one after another within the genome, while in dispersed repeats, these copies are randomly distributed. In this review we provide evidence that both tandem and dispersed repeats can have a similar organization, which leads us to suggest an update to their classification based on the sequence features, concretely regarding the presence or absence of retrotransposons/transposon specific domains. In addition, we analyze several studies that show that a repetitive element can be remodeled into repetitive non-coding or coding sequences, suggesting (1) an evolutionary relationship among DNA sequences, and (2) that the evolution of the genomes involved frequent repetitive sequence reshuffling, a process that we have designated as a “DNA remodeling mechanism”. The alternative classification of the repetitive DNA sequences here proposed will provide a novel theoretical framework that recognizes the importance of DNA remodeling for the evolution and plasticity of eukaryotic genomes.

Abundance and DNA sequence of two-base repeat regions in tropical tree genomes

Genome ◽  
1991 ◽  
Vol 34 (1) ◽  
pp. 66-71 ◽  
Author(s):  
Richard Condit ◽  
Stephen P. Hubbell
Keyword(s):  
Repetitive Dna ◽  
Length Variation ◽  
Dna Repeats ◽  
Dinucleotide Repeats ◽  
Genomic Libraries ◽  
Plant Genomes ◽  
Tropical Plant ◽  
Abundance Estimates ◽  
Phage Libraries ◽  
Forest Plants

Tandem DNA repeats of two-base pairs are potentially important tools for population genetic studies because of their abundance and length variation. As part of our research into the ecology of tropical forest plants, we began a study of dinucleotide repeat regions in several genera of tropical trees. Genomic libraries in bacteriophase λ were screened with the oligonucleotide probes poly(GT) and poly(AG). Both types of repeat regions were abundant in the genomes of all six plant species examined. Using the size of inserts in the phage libraries and number of phage screened, we estimated that there were 5 × 103 to 3 × 105 poly(AC) and poly(AG) sites per genome, with slightly more AG than AC sites. When libraries were made from smaller fragments of genomic DNA, abundance estimates were higher, suggesting that two-base repeat sites were clustered in the genome. Poly(AC) sites were 16–22 bp in length, and four of the five sequenced were adjacent to either poly(AG) or poly(AT) sites. Other repeat regions appeared in DNA flanking the AC sites. This further demonstrated that two-base repeats and other repetitive DNA were clustered in the genome. Two-base repeats are abundant in plant genomes and could provide a large number of polymorphic markers for studies of plant population genetics.Key words: repetitive DNA, dinucleotide repeats, tropical plant genomes.

A phylogenetic study of Pimelea and Thecanthes (Thymelaeaceae): evidence from plastid and nuclear ribosomal DNA sequence data

2010 ◽  
Vol 23 (4) ◽  
pp. 270 ◽  
Author(s):  
M. Cynthia Motsi ◽  
Annah N. Moteetee ◽  
Angela J. Beaumont ◽  
Barbara L. Rye ◽  
Martyn P. Powell ◽  
...  
Keyword(s):  
Sequence Data ◽  
Intergenic Spacer ◽  
Taxonomic Status ◽  
Molecular Study ◽  
Nuclear Ribosomal Dna ◽  
Phylogenetic Study ◽  
Rps16 Intron ◽  
Dna Sequence Data ◽  
Close Relationship ◽  
Nuclear Its

A comprehensive molecular study, using sequence data from nuclear ITS rDNA and plastid rbcL and matK exons, rps16 intron, and the trnL-F intronic and intergenic spacer, was used to assess the taxonomic status of Thecanthes Wikstr., and to evaluate the relationships within Pimelea Banks & Sol. ex Gaertn. and Thecanthes (Thymelaeaceae). Both genera are Australasian and they constitute the subtribe Pimeleinae, which is characterised by a reduction to two stamens. Previous studies indicated a close relationship among Pimelea, Thecanthes and Gnidia L. species from tropical Africa. We conclude that Pimelea and Thecanthes form a strongly supported clade, with Thecanthes possibly included within Pimelea, although we await further data before formally proposing a series of new taxonomic combinations.

scholarly journals Genetic Diversity and Molecular Characterization of Mosquitoes (Diptera: Culicidae) In North-Central Nigeria Using Ribosomal DNA ITS2 and Mitochondrial 16S-DNA Sequences

2020 ◽  
Vol 44 (2) ◽  
pp. 78-91
Author(s):  
Oluyinka A. Iyiola
Keyword(s):  
16S Rdna ◽  
Dna Sequences ◽  
Mosquito Species ◽  
Evolutionary Relationship ◽  
Malaria Vector Control ◽  
Phylogenetic Study ◽  
Its2 Region ◽  
Morphological Identification ◽  
North Central ◽  
Mitochondrial 16S Rdna

Mosquitoes are vectors of various life-threatening diseases like malaria, yellow fever, dengue fever etc. Their close proximity to human habitations allows ease for disease transmission. They have been identified by key morphological tools like their wings, legs, bristles etc. but closely related species are difficult to identify based on morphology. Molecular tools have, therefore, been employed to help with the more accurate identification. This study was aimed at identifying and characterizing different mosquito species in five different states in North-Central Nigeria using internal transcribed spacer 2 (ITS2) and mitochondrial 16S rDNA regions. Mosquito larvae were collected from stagnant water in breeding places at each collection site in North-central Nigeria. Morphological identification was carried out using standard keys. DNA extraction was performed using EZNA extraction kit. PCR amplification of ribosomal ITS2 and mitochondrial 16S-rDNA gene regions were carried out. The PCR amplicons were sequenced using primers initially used for the PCR. Sequence data were aligned in MEGA 6.0 using ClustalW multiple alignment feature and then compared with GenBank databases for similarity.  Phylogenetic analysis of DNA sequences from the ITS2 region was able to distinguish two mosquito subfamilies; Anophelinae and Culicinae as well as differentiate between and amongst Culex and Aedes species. However, it was unable to effectively distinguish between the two different species of Anopheles sequenced. Mitochondrial 16S rRNA marker was also able to distinguish the two mosquito subfamilies. It efficiently identified and differentiated Culex, Aedes and Anopheles mosquito species sequenced in this study. This study concludes that heterogeneity among Nigerian populations of Anopheles mosquitoes of may likely impact malaria vector control programs. We recommend the combination of nuclear and mitochondrial markers for effective and reliable phylogenetic study and determination of evolutionary relationship among mosquito species.

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