Intragenomic nuclear RNA variation in a cryptic Amanita taxon.

Amanita cf. lavendula collections in eastern North America, Mexico, and Costa Rica were found to consist of four cryptic taxa, one of which exhibited consistently unreadable nuclear rDNA ITS1-5.8S-ITS2 (fungal barcode) sequences after ITS1 base 130. This taxon is designated here as Amanita cf. lavendula taxon 1. ITS sequences from dikaryotic basidiomata were cloned, but sequences recovered from cloning did not segregate into distinct haplotypes. Rather, there was a mix of haplotypes that varied among themselves predominantly at 28 ITS positions. Analysis of each of these 28 variable bases showed predominantly two alternate bases at each position. Based on these findings and additional sequence data from the nuclear rDNA 28S, RNA polymerase II subunit 2 (RPB2) and mitochondrial rDNA small subunit (SSU) and 23S genes, we speculate that taxon 1 represents an initial hybridization event between two divergent taxa followed by failure of the ribosomal repeat to homogenize. Homogenization failure may be a result of repeated hybridization between divergent internal transcribed spacer (ITS) types with inadequate time for concerted evolution of the ribosomal repeat or, alternately, a complete failure of the ribosomal homogenization process. To our knowledge, this finding represents the first report of a geographically widespread taxon (Canada, eastern USA, Costa Rica) with apparent homogenization failure across all collections. Findings such as these have implications for fungal barcoding efforts and the application of fungal barcodes in identifying environmental sequences.

Las aneuploidías cromosómicas sexuales en la provincia Camagüey. Experiencia en 25 años de diagnóstico postnatal / Sexual chromosomal aneuploidies in the Camagüey province: 25 years experience of postnatal diagnosis

Entre las anomalías cromosómicas más comunes se encuentran las aneuploidias de cromosomas sexuales, en la actualidad el cariotipo en sangre periférica es la primera línea de estudio para la detección de estos problemas de salud. El objetivo de este trabajo fue describir los resultados del diagnóstico postnatal citogenético de aberraciones cromosómicas sexuales realizado en la provincia Camagüey durante 25 años de trabajo. Se realizó un estudio descriptivo transversal a partir de los resultados de los cariotipos en sangre periférica, las fórmulas cromosómicas obtenidas, el motivo de indicación de los mismos y la edad del diagnóstico. El universo incluyó a trescientos cincuenta pacientes que presentaron alguna alteración en su constitución cromosómica y la muestra se conformó con 108 pacientes que resultaron positivos para aberraciones cromosómicas sexuales. Los datos obtenidos fueron procesados, analizados y mostrados en gráficas y tablas. De las cromosomopatías descritas, el síndrome Turner y sus variedades fue el más representado, seguido por el síndrome Klinefelter; las indicaciones más frecuentes fueron hechas por signos clínicos de las mencionadas entidades y los diagnósticos fueron realizados fundamentalmente entre los 11 y 20 años de edad. En los últimos 4 años las aberraciones cromosómicas sexuales han disminuido su incidencia, no obstante, estas deben ser sospechadas en edades tempranas de la vida para poder mejorar la atención médica…(AU)

The systematic position of Leptorhynchoides (Kostylew, 1924) and Pseudoleptorhynchoides (Salgado-Maldonado, 1976), inferred from nuclear and mitochondrial DNA gene sequences.

The systematic relationships of acanthocephalans, including Leptorhynchoides and Pseudoleptorhynchoides that occur in freshwater and marine fishes in Neartic and Neotropical regions, are enigmatic. Leptorhynchoides (3 species) and Pseudoleptorhynchoides (1 species) are presently classified in the Rhadinorhynchidae. However, recent molecular and morphological phylogenies have challenged the monophyly of this family. Sequences of nuclear ribosomal DNA (large subunit, small subunit regions) and the mitochondrial cytochrome c oxidase subunit I gene of Leptorhynchoides thecatus and Pseudoleptorhynchoides lamothei were used in phylogenetic analyses with available sequences of 26 other acanthocephalans. Maximum parsimony and maximum likelihood analyses were identical in placing both genera in the Illiosentidae. Bootstrap analyses also indicate that placement of these genera with members of Illiosentidae is reliably supported.

Localization of intranuclear RNA by electron microscopy in situ hybridization using a genomic DNA probe

Background. The presence of RNA in the cell nucleus is well known. However, a high resolution in situ hybridization evidence for the presence of RNA in some nuclear particles is still lacking. The aim of this work is to localize RNA in subnuclear particles using a novel ultrastructural in situ hybridization procedure. In this study, biotinylated genomic mouse DNA as a probe to localiza total RNA in the nuclei of mouse hepatocytes was used. Methods. The procedure is based on Paraformaldehyde fixation and embedding in lowicryl resin. Thin sections are mounted in formvar-coated gold grids. Hybridization is performed on non-denatured thin sections. DNA-RNA hybrids are detected with streptavidin-10 mm gold particles complex. By controlling the time of nick-translation during incorporation of biotin into the probe, labeling in the fibrillar portions of the nucleoplasm is obtained. More digested probes generate more labeling in the granular components. Nucleoli were similarly labeled. Results. As expected, no label was observed in the compact chromatin clumps. These results indicate that granular components as perichromatin granules in the nucleus contain more processed RNA than fibrillar portions. As a comparison, viral DNA sequences on denatured RNase-treated thin sections of adenovirus-2 (Ad-2)-infected human cells were detected. As previously reported, at late stages DNA was observed in the viral particles and surrounding nucleoplasm, where Ad-2 DNA is synthesized. Conclusions. The present procedure allows the study of intranuclear RNA distribution and will be useful fo the analysis of RNA processing in several types of cells