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.

scholarly journals Organization of 5S rDNA repeated unit of Quercus imbricaria Michx.

2020 ◽  
Vol 17 (2) ◽  
pp. 179-186 ◽  
Author(s):  
A. S. Stratiichuk ◽  
T. O. Derevenko ◽  
Y. O. Tynkevych
Keyword(s):  
Molecular Evolution ◽  
Secondary Structure ◽  
Pcr Amplification ◽  
5S Rdna ◽  
5S Rrna ◽  
Molecular Organization ◽  
Coding Region ◽  
Nucleotide Substitutions ◽  
Sequence Elements ◽  
Related Plant

Aim. The 5S rDNA repeats represent a universal model for the investigation of molecular evolution of repeated sequences. Also, comparison of 5S rDNA was successfully applied for the elucidation of phylogenetic relationships between the closely related plant species. However, there is practically no data regarding the molecular organization of 5S rDNA repeats in members of the section Lobatae, one of the largest groups of the genus Quercus. Accordingly, our aim was to investigate the 5S rDNA organization for Q. imbricaria, a species that belongs to this section. Methods. DNA extraction, PCR amplification, cloning and sequencing. Results. A complete 5S rDNA repeat of Q. imbricaria was cloned and sequenced. It has been found that in the oak genome, the 5S rDNA coding region contains five nucleotide substitutions as compared to that in Arabidopsis. Nevertheless, the predicted secondary structure of the transcript retains all typical features of 5S rRNA. Presumptive sequence elements of the external promoter were identified in the IGS. Conclusions. The nucleotide substitutions that occur in the 5S rRNA during evolution appear to be compensatory, resulting in conservation of its secondary structure. Due to considerable differences among the species of different sections, the 5S rDNA IGS can be applied for the taxonomic studies in the genus Quercus. Keywords: 5S rDNA, molecular evolution, Quercus, Lobatae.

Inferring evolutionary processes from DNA sequence data

2019 ◽  
pp. 145-172
Author(s):  
Glenn-Peter Sætre ◽  
Mark Ravinet
Keyword(s):  
Molecular Evolution ◽  
Dna Sequence ◽  
Genetic Markers ◽  
Dna Sequences ◽  
Sequence Data ◽  
Neutral Theory ◽  
Evolutionary Genetics ◽  
Haplotype Structure ◽  
Dna Sequence Data ◽  
Neutrality Tests

The allelic evolutionary genetic models explored so far are applicable to genetic markers. However, DNA sequences harbor a lot of information about the evolutionary past that would be missed if different sequences were simply treated as different alleles. This chapter introduces some important methods and concepts applicable to the analysis of DNA-sequence data. The null models for analyzing sequence data are derived from the neutral theory of molecular evolution. Historically, however, the neutral theory has made a large impact on evolutionary genetics. Therefore, this chapter starts by reviewing its important contribution. Then, important parameters and statistics for analyzing sequence variation are introduced, including a plethora of neutrality tests. The chapter ends with a cautious focus on the powerful tool of genome scan analysis and its utility for identifying regions of the genomes potentially under selection. This includes a section on more recently derived statistics which incorporate information on haplotype structure.

scholarly journals Characterization of squalene synthase gene from Gymnema sylvestre R. Br.

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Kuldeepsingh A. Kalariya ◽  
Ram Prasnna Meena ◽  
Lipi Poojara ◽  
Deepa Shahi ◽  
Sandip Patel
Keyword(s):  
Dna Sequences ◽  
Genomic Dna ◽  
Competitive Inhibition ◽  
Sequence Data ◽  
Homology Model ◽  
Squalene Synthase ◽  
Gymnema Sylvestre ◽  
Gardenia Jasminoides ◽  
Ramachandran Plots ◽  
Flanking Regions

Abstract Background Squalene synthase (SQS) is a rate-limiting enzyme necessary to produce pentacyclic triterpenes in plants. It is an important enzyme producing squalene molecules required to run steroidal and triterpenoid biosynthesis pathways working in competitive inhibition mode. Reports are available on information pertaining to SQS gene in several plants, but detailed information on SQS gene in Gymnema sylvestre R. Br. is not available. G. sylvestre is a priceless rare vine of central eco-region known for its medicinally important triterpenoids. Our work aims to characterize the GS-SQS gene in this high-value medicinal plant. Results Coding DNA sequences (CDS) with 1245 bp length representing GS-SQS gene predicted from transcriptome data in G. sylvestre was used for further characterization. The SWISS protein structure modeled for the GS-SQS amino acid sequence data had MolProbity Score of 1.44 and the Clash Score 3.86. The quality estimates and statistical score of Ramachandran plots analysis indicated that the homology model was reliable. For full-length amplification of the gene, primers designed from flanking regions of CDS encoding GS-SQS were used to get amplification against genomic DNA as template which resulted in approximately 6.2-kb sized single-band product. The sequencing of this product through NGS was carried out generating 2.32 Gb data and 3347 number of scaffolds with N50 value of 457 bp. These scaffolds were compared to identify similarity with other SQS genes as well as the GS-SQSs of the transcriptome. Scaffold_3347 representing the GS-SQS gene harbored two introns of 101 and 164 bp size. Both these intronic regions were validated by primers designed from adjoining outside regions of the introns on the scaffold representing GS-SQS gene. The amplification took place when the template was genomic DNA and failed when the template was cDNA confirmed the presence of two introns in GS-SQS gene in Gymnema sylvestre R. Br. Conclusion This study shows GS-SQS gene was very closely related to Coffea arabica and Gardenia jasminoides and this gene harbored two introns of 101 and 164 bp size.

scholarly journals Molecular evolution of the plant R regulatory gene family.

Genetics ◽  
1994 ◽  
Vol 138 (3) ◽  
pp. 849-854
Author(s):  
M D Purugganan ◽  
S R Wessler
Keyword(s):  
Molecular Evolution ◽  
Gene Family ◽  
Plant Species ◽  
Regulatory Gene ◽  
Nonsynonymous Substitution ◽  
R Genes ◽  
Nucleotide Substitutions ◽  
Variable Regions ◽  
Helix Loop Helix ◽  
Regulatory Loci

Abstract Anthocyanin pigmentation patterns in different plant species are controlled in part by members of the myc-like R regulatory gene family. We have examined the molecular evolution of this gene family in seven plant species. Three regions of the R protein show sequence conservation between monocot and dicot R genes. These regions encode the basic helix-loop-helix domain, as well as conserved N-terminal and C-terminal domains; mean replacement rates for these conserved regions are 1.02 x 10(-9) nonsynonymous nucleotide substitutions per site per year. More than one-half of the protein, however, is diverging rapidly, with nonsynonymous substitution rates of 4.08 x 10(-9) substitutions per site per year. Detailed analysis of R homologs within the grasses (Poaceae) confirm that these variable regions are indeed evolving faster than the flanking conserved domains. Both nucleotide substitutions and small insertion/deletions contribute to the diversification of the variable regions within these regulatory genes. These results demonstrate that large tracts of sequence in these regulatory loci are evolving at a fairly rapid rate.

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

scholarly journals SHI7 Is a Self-Learning Pipeline for Multipurpose Short-Read DNA Quality Control

mSystems ◽  
2018 ◽  
Vol 3 (3) ◽  
Author(s):  
Gabriel A. Al-Ghalith ◽  
Benjamin Hillmann ◽  
Kaiwei Ang ◽  
Robin Shields-Cutler ◽  
Dan Knights
Keyword(s):  
Quality Control ◽  
Dna Sequences ◽  
Sequence Data ◽  
Background Knowledge ◽  
Sequencing Technology ◽  
Data Set ◽  
Short Read ◽  
Dna Quality ◽  
Public Data ◽  
User Friendly

ABSTRACT Next-generation sequencing technology is of great importance for many biological disciplines; however, due to technical and biological limitations, the short DNA sequences produced by modern sequencers require numerous quality control (QC) measures to reduce errors, remove technical contaminants, or merge paired-end reads together into longer or higher-quality contigs. Many tools for each step exist, but choosing the appropriate methods and usage parameters can be challenging because the parameterization of each step depends on the particularities of the sequencing technology used, the type of samples being analyzed, and the stochasticity of the instrumentation and sample preparation. Furthermore, end users may not know all of the relevant information about how their data were generated, such as the expected overlap for paired-end sequences or type of adaptors used to make informed choices. This increasing complexity and nuance demand a pipeline that combines existing steps together in a user-friendly way and, when possible, learns reasonable quality parameters from the data automatically. We propose a user-friendly quality control pipeline called SHI7 (canonically pronounced “shizen”), which aims to simplify quality control of short-read data for the end user by predicting presence and/or type of common sequencing adaptors, what quality scores to trim, whether the data set is shotgun or amplicon sequencing, whether reads are paired end or single end, and whether pairs are stitchable, including the expected amount of pair overlap. We hope that SHI7 will make it easier for all researchers, expert and novice alike, to follow reasonable practices for short-read data quality control. IMPORTANCE Quality control of high-throughput DNA sequencing data is an important but sometimes laborious task requiring background knowledge of the sequencing protocol used (such as adaptor type, sequencing technology, insert size/stitchability, paired-endedness, etc.). Quality control protocols typically require applying this background knowledge to selecting and executing numerous quality control steps with the appropriate parameters, which is especially difficult when working with public data or data from collaborators who use different protocols. We have created a streamlined quality control pipeline intended to substantially simplify the process of DNA quality control from raw machine output files to actionable sequence data. In contrast to other methods, our proposed pipeline is easy to install and use and attempts to learn the necessary parameters from the data automatically with a single command.

scholarly journals Diversity of echinostomes (Digenea: Echinostomatidae) in their snail hosts at high latitudes

Parasite ◽  
2021 ◽  
Vol 28 ◽  
pp. 59
Author(s):  
Camila Pantoja ◽  
Anna Faltýnková ◽  
Katie O’Dwyer ◽  
Damien Jouet ◽  
Karl Skírnisson ◽  
...  
Keyword(s):  
North America ◽  
Dna Sequences ◽  
Sequence Data ◽  
Molecular Data ◽  
Migratory Bird ◽  
Parasite Fauna ◽  
Life Cycles ◽  
Freshwater Ecosystems ◽  
Trematode Species ◽  
Host Life

The biodiversity of freshwater ecosystems globally still leaves much to be discovered, not least in the trematode parasite fauna they support. Echinostome trematode parasites have complex, multiple-host life-cycles, often involving migratory bird definitive hosts, thus leading to widespread distributions. Here, we examined the echinostome diversity in freshwater ecosystems at high latitude locations in Iceland, Finland, Ireland and Alaska (USA). We report 14 echinostome species identified morphologically and molecularly from analyses of nad1 and 28S rDNA sequence data. We found echinostomes parasitising snails of 11 species from the families Lymnaeidae, Planorbidae, Physidae and Valvatidae. The number of echinostome species in different hosts did not vary greatly and ranged from one to three species. Of these 14 trematode species, we discovered four species (Echinoparyphium sp. 1, Echinoparyphium sp. 2, Neopetasiger sp. 5, and Echinostomatidae gen. sp.) as novel in Europe; we provide descriptions for the newly recorded species and those not previously associated with DNA sequences. Two species from Iceland (Neopetasiger islandicus and Echinoparyphium sp. 2) were recorded in both Iceland and North America. All species found in Ireland are new records for this country. Via an integrative taxonomic approach taken, both morphological and molecular data are provided for comparison with future studies to elucidate many of the unknown parasite life cycles and transmission routes. Our reports of species distributions spanning Europe and North America highlight the need for parasite biodiversity assessments across large geographical areas.

scholarly journals Characterization of an unusually conserved AluI highly reiterated DNA sequence family from the honeybee, Apis mellifera.

Genetics ◽  
1993 ◽  
Vol 134 (4) ◽  
pp. 1195-1204
Author(s):  
S Tarès ◽  
J M Cornuet ◽  
P Abad
Keyword(s):  
Apis Mellifera ◽  
Dna Sequence ◽  
Dna Sequences ◽  
Sequence Data ◽  
Sequence Divergence ◽  
Repeated Sequence ◽  
Consensus Sequences ◽  
Dna Sequence Data ◽  
Repeat Class ◽  
Honeybee Subspecies

Abstract An AluI family of highly reiterated nontranscribed sequences has been found in the genome of the honeybee Apis mellifera. This repeated sequence is shown to be present at approximately 23,000 copies per haploid genome constituting about 2% of the total genomic DNA. The nucleotide sequence of 10 monomers was determined. The consensus sequences is 176 nucleotides long and has an A + T content of 58%. There are clusters of both direct and inverted repeats. Internal subrepeating units ranging from 11 to 17 nucleotides are observed, suggesting that it could have evolved from a shorter sequence. DNA sequence data reveal that this repeat class is unusually homogeneous compared to the other class of invertebrate highly reiterated DNA sequences. The average pairwise sequence divergence between the repeats is 2.5%. In spite of this unusual homogeneity, divergence has been found in the repeated sequence hybridization ladder between four different honeybee subspecies. Therefore, the AluI highly reiterated sequences provide a new probe for fingerprinting in A. m. mellifera.

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