RESUMEN
Non-Long Terminal Repeats (non-LTR or LINE) retrotransposons belong to the class of mobile genetic elements that are transposed into the host genome by reverse transcription of the RNA intermediate. Most of non-LTR retrotransposons contain two open reading frames (ORFs). The ORF1 codes for a gag-like protein, while the ORF2 codes for a reverse transcriptase (RT). We cloned two constructs based on Jockey-like non-LTR retrotransposon from genome Chironomus thummi (NLR1Cth). The retroposition assay performed in Chinese hamster ovary (CHO) cells demonstrated genome integrations of both constructs. The finding that the insect mobile element NLR1Cth is functional in mammalian cells demonstrates that this element possess universal enzymatic machinery allowing for active propagation in the genome of distant taxa. This suggests that the NLR1Cth transposon system may represent a useful tool for genetic analysis and manipulation in vertebrate cells.
Asunto(s)
Chironomidae , Genoma de los Insectos , Proteínas de Insectos/metabolismo , Elementos de Nucleótido Esparcido Largo/fisiología , Sistemas de Lectura Abierta/fisiología , ADN Polimerasa Dirigida por ARN/metabolismo , Animales , Células CHO , Cricetinae , Cricetulus , Proteínas de Insectos/genética , ADN Polimerasa Dirigida por ARN/genéticaRESUMEN
The diversity of mobile elements, in particular LTR retrotransposons, in basidiomycetes fungi has been poorly studied. Using complete genomic sequences, we have for the first time screened the genome of the lignin-degrading fungus Phanerochaete chrysosporium for LTR retrotransposons. A surprisingly high diversity of LTR retrotransposons was found. Twenty-three novel mobile elements from two superfamilies, Pseudoviridae and Metaviridae, were described. The proportion of LTR retrotransposons in the P. chrysosporium genome is low, constituting only about 3%. Nevertheless, LTR retrotransposons of P. chrysosporium represent a dynamic part of the genome, which is evidenced by the presence of intact copies with signs of recent transposition and numerous solo LTR elements. Phylogenetic and structural analyses detected mobile elements having characteristics that had been previously unknown for other LTR retrotransposons.
Asunto(s)
Genoma Fúngico/genética , Phanerochaete/genética , Filogenia , Retroelementos/genética , Secuencias Repetidas Terminales/genéticaRESUMEN
Non-LTR retrotransposons are an ancient group of retroelements. Twenty-one clades are distinguished today among non-LTR retrotransposons. The presence of different clades in the genome characterizes the diversity of non-LTR retrotransposons of the organism. This review presents a general picture of the evolution and distribution of different clades of non-LTR retrotransposons among the main taxa of eukaryotic organisms: protozoa, plants, fungi, and metazoa. Introduction in the analysis of new taxa and the use of new bioinformatic and experimental approaches can significantly extend our knowledge about non-LTR retrotransposons and their role in the evolution and functioning of eukaryotic genomes.
Asunto(s)
Células Eucariotas/fisiología , Evolución Molecular , Retroelementos/fisiología , Animales , Hongos/genética , Hongos/metabolismo , Humanos , Plantas/genética , Plantas/metabolismoRESUMEN
Repeat-induced point mutation (RIP) is the most intriguing among the known mechanisms of repeated sequences inactivation because of its ability to produce irreversible mutation of repeated DNA. Discovered for the first time in Neurospora crassa, RIP is characterized by C:G to T:A transitions in duplicated sequences. The mechanisms and distribution of RIP are still purely investigated. Mobile elements are a common target for the processes which lead to homology-dependent silencing because of their ability to propagate themselves. We have done comparative analysis of LTR retrotransposons in genomic scale from genomes of two aspergilli fungi--Aspergillus funmigatus and A. nidulans, based on several copies we reconstructed "de-RIP" retroelements. Investigations of frequencies of CpG, CpA and TpG sites, which are potential targets for mutagenesis, showed the much lower frequencies of these sites in mobile elements in comparison with structural genes. LTR retrotransposons from A. fumigatus and A. nidulans have different ratio of types of substitutions. Our analysis indicates that two investigated fungi have or had the RIP-like processes for repeated sequences inactivation, in various modes. Whereas in A. fumigatus the context for mutagenesis consists of both CpG and CpA sites, in A. nidulans inactivation seems to proceed only on CpG dinucleotides. The present investigation gives a theoretical background for planning of experimental studying of RIP inactivation in aspergilli.
Asunto(s)
Aspergillus fumigatus/genética , Aspergillus nidulans/genética , Genoma Fúngico , Retroelementos , Silenciador del Gen , Mutagénesis , Mutación Puntual , Secuencias Repetitivas de Ácidos NucleicosRESUMEN
Fungi Aspergillus spp. are able to infect all tissues and organs and often cause invasive mycosis (aspergillosis), which is usually a fatal disease, especially in the patients with compromised immune system. Microbiological monitoring of these infectious agents is necessary in modem medical facilities. Mobile elements can be used as markers for identification of species and strains of Aspergillus found indoors as well as in aspergillosis diagnostics. Genomic sequences of two representative Aspergillus species, A. fumigatus and A. nidulans, were analysed in silico in order to detect LTR retrotransposons. We found considerable differences in the composition of retrotransposon families between two studied species. One of the detected families, which is present in both studied Aspergillus species, is phylogenetically quite different from all other known fungal retrotransposons. The majority of elements are represented by damaged copies. Nevertheless, we describe for the first time allegedly non-damaged LTR copies that contain intact ORFs and could be active.
Asunto(s)
Aspergillus fumigatus/genética , Aspergillus nidulans/genética , Genoma Fúngico/genética , Filogenia , Retroelementos/genética , Secuencias Repetidas Terminales/genética , Aspergilosis/genética , Aspergilosis/inmunología , Aspergillus fumigatus/inmunología , Aspergillus nidulans/inmunología , Genoma Fúngico/inmunología , Sistemas de Lectura Abierta/genética , Sistemas de Lectura Abierta/inmunología , Retroelementos/inmunología , Análisis de Secuencia de ADN/métodos , Especificidad de la Especie , Secuencias Repetidas Terminales/inmunologíaRESUMEN
The paper studies the age-related X-ray features of the spine in patients with achondroplasia. It gives the time course of changes in the shape of vertebrae, the specific features of apophyseal ossification, provides a quantitative account of the shorter caudal lumbar vertebral arch root distance symptom. The time course of changes in the size of the lumbosacral angle was examined. The findings suggest that there are not only considerable static changes in the spine of patients with achondroplasia, but also significant age-related features of vertebral tissue growth and differentiation.
Asunto(s)
Acondroplasia/diagnóstico por imagen , Columna Vertebral/diagnóstico por imagen , Adolescente , Adulto , Factores de Edad , Niño , Preescolar , Femenino , Humanos , Masculino , RadiografíaRESUMEN
O-Linked oligosaccharides from N,O-glycoproteins were selectively split off by treatment with alkaline sodium borohydride in the presence of cadmium salt. The side reaction of reductive cleavage of N-glycosylamide and peptide bonds, observed under standard conditions of splitting of O-linked chains (M NaBH4 and 50mM NaOH, 16 h, 50 degrees), was inhibited by addition of 50-10 mM cadium acetate and 5-10mM EDTA.Na4, as shown by treatment of model compounds and several glycoproteins (ovomucoid, group-specific glycoproteins H and B, fetuin, and asialofetuin). This treatment, in combination with the previously developed procedure for the release of the N-linked oligosaccharide chains by lithium borohydride, allows a sequential, selective cleavage of O-, and then N-linked oligosaccharides from N,O-glycoproteins by chemical methods.
