Search results for "ribosomal DNA"

Relationships of the Woody Medicago Species (Section Dendrotelis) Assessed by Molecular Cytogenetic Analyses

2008

†Background and Aims The organization of rDNA genes in the woody medic species from the agronomically important Medicago section Dendrotelis was analysed to gain insight into their taxonomic relationships, to assess the levels of infraspecific variation concerning ribosomal loci in a restricted and fragmented insular species (M. citrina) and to assess the nature of its polyploidy. †Methods Fluorescence in situ hybridization (FISH) was used for physical mapping of 5S and 45S ribosomal DNA genes in the three species of section Dendrotelis (M. arborea, M. citrina, M. strasseri) and the related M. marina from section Medicago. Genomic in situ hybridization (GISH) was used to assess the genomic …

Molecular and morphological identification of larval opecoelids (Digenea: Opecoelidae) parasitising prosobranch snails in a Western Mediterranean lag…

2012

In a study of the digeneans parasitising molluscs in the Els Alfacs lagoon (Ebro Delta, Western Mediterranean) we found heavy infections with sporocysts emitting two types of cotylocercous cercariae in the prosobranch trochid gastropod Gibbula adansonii and with metacercariae in the prosobranch nassariid gastropod Cyclope neritea. A comparative analysis using ITS ribosomal DNA sequences from these larval stages and published sequences of 17 larval and adult opecoelid stages allowed us to elucidate the life-cycle of Macvicaria obovata and to confirm the identification of Cainocreadium labracis based on cercarial morphology. We provide molecular evidence for the identification and the first d…

Nuclear rDNA-based molecular clock of the evolution of Triatominae (Hemiptera : Reduviidae), vectors of Chagas disease

2000

The evolutionary history and times of divergence of triatomine bug lineages are estimated from molecular clocks inferred from nucleotide sequences of the small subunit SSU (18S) and the second internal transcribed spacer (ITS-2) of the nuclear ribosomal DNA of these reduviids. The 18S rDNA molecular clock rate in Triatominae, and Prosorrhynchan Hemiptera in general, appears to be of 1.8% per 100 million years (my). The ITS-2 molecular clock rate in Triatominae is estimated to be around 0.4-1% per 1 my, indicating that ITS-2 evolves 23-55 times faster than 18S rDNA. Inferred chronological data about the evolution of Triatominae fit well with current hypotheses on their evolutionary histories…

A nuclear ribosomal DNA pseudogene in triatomines opens a new research field of fundamental and applied implications in Chagas disease

2015

A pseudogene, designated as "ps(5.8S+ITS-2)", paralogous to the 5.8S gene and internal transcribed spacer (ITS)-2 of the nuclear ribosomal DNA (rDNA), has been recently found in many triatomine species distributed throughout North America, Central America and northern South America. Among characteristics used as criteria for pseudogene verification, secondary structures and free energy are highlighted, showing a lower fit between minimum free energy, partition function and centroid structures, although in given cases the fit only appeared to be slightly lower. The unique characteristics of "ps(5.8S+ITS-2)" as a processed or retrotransposed pseudogenic unit of the ghost type are reviewed, wi…

A case of endocarditis with vasculitis due to Actinobacillus actinomycetemcomitans: a 16S rDNA signature for distinction from related organisms.

1998

DNA multigene sequencing of topotypic specimens of the fascioliasis vector Lymnaea diaphana and phylogenetic analysis of the genus Pectinidens (Gastr…

2012

Freshwater lymnaeid snails are crucial in defining transmission and epidemiology of fascioliasis. In South America, human endemic areas are related to high altitudes in Andean regions. The species Lymnaea diaphana has, however, been involved in low altitude areas of Chile, Argentina and Peru where human infection also occurs. Complete nuclear ribosomal DNA 18S, internal transcribed spacer (ITS)-2 and ITS-1 and fragments of mitochondrial DNA 16S and cytochrome c oxidase (cox)1 genes of L. diaphana specimens from its type locality offered 1,848, 495, 520, 424 and 672 bp long sequences. Comparisons with New and Old World Galba/Fossaria, Palaearctic stagnicolines, Nearctic stagnicolines, Old Wo…

Systematics of Mepraia (Hemiptera-Reduviidae): cytogenetic and molecular variation.

2009

The haematophagous insects of the subfamily Triatominae (Hemiptera-Reduviidae) have great epidemiological importance as vectors of Trypanosoma cruzi, the causative agent of Chagas disease. Mepraia was originally described as a monotypic genus comprised of Mepraia spinolai, distributed along coastal areas of northern Chile (from Region I to the Metropolitan Region). Recently, some M. spinolai populations have been ranked as a new species named Mepraia gajardoi. Several populations along the distribution range of the genus were sampled, and genetic differentiation was studied based upon the analysis of three molecular markers: cytogenetics (karyotype and chromosome behaviour during meiosis us…

Identification of Colletotrichum species responsible for anthracnose of strawberry based on the internal transcribed spacers of the ribosomal region.

2000

In recent years, different molecular techniques have led to an important progress in the characterisation of Colletotrichum species, but there are no available methods which permit the easy identification of Colletotrichum strains and their assignation to classical species. In the present work, the restriction patterns generated from the region spanning the internal transcribed spacers (ITS1 and ITS2) and the 5.8S rRNA gene, were used to identify a total of 80 strains of Colletotrichum, the majority of them isolated from strawberry. One of the most interesting results derived from this study was the easy and reliable distinction, using the endonuclease MvnI, between Colletotrichum fragariae…

Characterisation of Lymnaea cubensis, L. viatrix and L. neotropica n. sp., the main vectors of Fasciola hepatica in Latin America, by analysis of the…

2007

Although, in the endemic areas throughout the world, human fascioliasis presents varying patterns in its epidemiology, the species of lymnaeid snail that act as intermediate hosts and vectors are always crucial in the transmission of the causative parasites. Species in the Galba/Fossaria group of snails, such as Lymnaea cubensis, L. viatrix var. A ventricosa, L. viatrix var. B elongata and Galba truncatula, appear to be frequently involved in the transmission of Fasciola hepatica in Central and South America, although specific classification within this morphologically and anatomically confusing group is often very difficult. To explore the potential use of molecular analyses in the identif…

Isolation and Characterization of Novosphingobium sp. Strain MT1, a Dominant Polychlorophenol-Degrading Strain in a Groundwater Bioremediation System

2002

ABSTRACT A high-rate fluidized-bed bioreactor has been treating polychlorophenol-contaminated groundwater in southern Finland at 5 to 8°C for over 6 years. We examined the microbial diversity of the bioreactor using three 16S ribosomal DNA (rDNA)-based methods: denaturing gradient gel electrophoresis, length heterogeneity-PCR analysis, and restriction fragment length polymorphism analysis. The molecular study revealed that the process was dependent on a stable bacterial community with low species diversity. The dominant organism, Novosphingobium sp. strain MT1, was isolated and characterized. Novosphingobium sp. strain MT1 degraded the main contaminants of the groundwater, 2,4,6-trichloroph…