RESUMEN
The fatty acid composition of four microsporidian species (Glugea atherinae, Spraguea lophii, Glugea americanus, and Pleistophora mirandellae) and their host fishes has been determined using gas chromatography. Twenty-four fatty acids were identified with differences in relative abundance of fatty acids among the four parasites. Certain even-saturated fatty acids were found in a very high proportion: palmitic acid (16:0) represented one-third of total fatty acids in Pleistophora mirandellae. The level of docosahexaenoic acid (22:6omega3) attained 26-28% in Glugea atherinae, Spraguea lophii, and Glugea americanus, but only 8-9% in P. mirandellae. With respect to fatty acid compositions of host organs, some significant differences were evident between marine and freshwater fishes. Palmitic acid was prevalent in the marine fishes, Atherinae boyeri and Lophius piscatorius, and oleic acid (18:1omega9) in the freshwater fish Leuciscus cephalus. The proportion of docosahexaenoic acid in marine fishes was two or three times as great as in freshwater fish Leuciscus. The high polyunsaturated fatty acid content in both parasites and host fishes may be related to the scavenging of these fatty acids by the parasites rather than a microsporidia-specific fatty acid biosynthesis pathway.
Asunto(s)
Ácidos Grasos/análisis , Enfermedades de los Peces/parasitología , Peces , Microsporida/química , Microsporidiosis/veterinaria , Animales , Cromatografía de Gases , Agua Dulce , Riñón/química , Hígado/química , Microsporidiosis/parasitología , Agua de Mar , Esporas/químicaAsunto(s)
Cromosomas/genética , Encephalitozoon cuniculi/genética , Genes Protozoarios/genética , Proteínas Protozoarias/genética , Animales , Cinesinas/genética , Proteínas de Unión al ARN/genética , Receptores Citoplasmáticos y Nucleares/genética , Receptores de Péptidos/genética , Análisis de Secuencia de ADN , Factores de Escisión y Poliadenilación de ARNmRESUMEN
The microsporidian Encephalitozoon cuniculi can infect numerous mammals, including man. Three strains of E. cuniculi have been identified so far, the major marker being the number of a tetranucleotide repeats in the rDNA internal transcribed spacer. We investigated diversity at the chromosomal level through the electrophoretic karyotypes obtained from 15 E. cuniculi isolates from 5 different host species. All preparations provided patterns with 9-12 bands within a narrow molecular size range. Six karyotype forms were distinguished, involving subdivision of strain I into 3 types (A, B, C) and strain II into 2 types (D, E). The types A, B and C were mainly associated with isolates from rabbits of different geographical origins. The types D, E and F were characterized by a reduced chromosome size range, 2 of these appearing specific to a carnivorous host species (D in dog and F in blue fox). Hybridization experiments showed that all E. cuniculi isolates possess 11 chromosomes, with a size polymorphism entailing occasional electrophoretic comigration of heterologous chromosomes and differential migration of homologous ones. DNA rearrangements should occur during mitosis and the hypothesis of diploidy for the basic state of E. cuniculi seems likely.
Asunto(s)
Encephalitozoon cuniculi/genética , Encefalitozoonosis/prevención & control , Variación Genética/genética , Animales , Mapeo Cromosómico , Sondas de ADN/química , ADN Protozoario/química , Perros , Electroforesis en Gel de Campo Pulsado , Encephalitozoon cuniculi/química , Zorros , Humanos , Ratones , Repeticiones de Microsatélite , Hibridación de Ácido Nucleico , Polimorfismo Genético , ConejosAsunto(s)
Encephalitozoon cuniculi/genética , Intrones/genética , Proteínas Ribosómicas/genética , Empalmosomas , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Mapeo Cromosómico , Genes Protozoarios , Datos de Secuencia Molecular , Proteínas Protozoarias/genética , ARN Ribosómico 16S/genética , Alineación de SecuenciaRESUMEN
Microsporidia are eukaryotic parasites lacking mitochondria, the ribosomes of which present prokaryote-like features. In order to better understand the structural evolution of rRNA molecules in microsporidia, the 5S and rDNA genes were investigated in Encephalitozoon cuniculi . The genes are not in close proximity. Non-tandemly arranged rDNA units are on every one of the 11 chromosomes. Such a dispersion is also shown in two other Encephalitozoon species. Sequencing of the 5S rRNA coding region reveals a 120 nt long RNA which folds according to the eukaryotic consensus structural shape. In contrast, the LSU rRNA molecule is greatly reduced in length (2487 nt). This dramatic shortening is essentially due to truncation of divergent domains, most of them being removed. Most variable stems of the conserved core are also deleted, reducing the LSU rRNA to only those structural features preserved in all living cells. This suggests that the E.cuniculi LSU rRNA performs only the basic mechanisms of translation. LSU rRNA phylogenetic analysis with the BASEML program favours a relatively recent origin of the fast evolving microsporidian lineage. Therefore, the prokaryote-like ribosomal features, such as the absence of ITS2, may be derived rather than primitive characters.
Asunto(s)
Encephalitozoon cuniculi/genética , Conformación de Ácido Nucleico , ARN Protozoario , ARN Ribosómico 5S , ARN Ribosómico , Animales , Secuencia de Bases , Mapeo Cromosómico , ADN Ribosómico , Células Eucariotas , Datos de Secuencia Molecular , Filogenia , ARN Protozoario/química , ARN Ribosómico/química , ARN Ribosómico 5S/química , RibosomasRESUMEN
The molecular karyotype of a murine isolate of Encephalitozoon cuniculi, a microsporidian with a wide range of mammalian hosts, comprises eleven chromosomes ranging in size between 217 and 315 kb. To determine specific chromosomal markers, a partial genomic library was constructed and cloned DNA fragments were hybridized to chromosomal bands separated by pulsed-field gel electrophoresis. Most probes were assigned to single chromosomes, indicating prevalence of low-copy number nucleotide sequences within the very small genome of E. cuniculi (2.9 Mb). A few probes were shown to hybridize to all chromosomes. These repetitive DNA fragments corresponded to either rRNA genes or some non-coding regions whose sequences were characterized by short micro- and minisatellites. The chromosomal locations of beta-tubulin genes and six newly identified protein-encoding genes were determined. Genes encoding dihydrofolate reductase, thymidylate synthase, serine hydroxymethyl transferase, a cdc2 kinase-like protein and helicase ERCC6-like protein were each located on a single chromosome whereas genes for both beta-tubulin and aminopeptidase were on two different chromosomes. The mapping will serve as a reference for further analysis of intraspecific karyotype polymorphism in different isolates from different host species.
Asunto(s)
Mapeo Cromosómico , Sondas de ADN , ADN Protozoario , Encephalitozoon cuniculi/genética , Secuencias Repetitivas de Ácidos Nucleicos , Animales , Secuencia de Bases , ADN Complementario , Humanos , Ratones , Datos de Secuencia Molecular , Hibridación de Ácido Nucleico , Análisis de Secuencia de ADNRESUMEN
The cDNA encoding the Toxoplasma gondii microneme protein MIC1 and the corresponding gene have been cloned and sequenced. The MIC1 gene contains three introns. The cDNA encodes a 456 amino acid (aa) sequence, with a typical signal sequence and no other trans-membrane domain. The protein contains a tandemly duplicated domain with conservation of cysteines and presents distant homology with the Plasmodium sp. microneme protein TRAP-SSP2. The MIC1 protein from tachyzoite lysates and a PMAL recombinant expressing the N-terminal duplicated domain of the protein bound to the surface of putative host cells, suggesting a possible involvement of MIC1 in host cell binding/recognition.
Asunto(s)
Moléculas de Adhesión Celular/genética , Moléculas de Adhesión Celular/metabolismo , Proteínas Protozoarias , Toxoplasma/genética , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Adhesión Celular , Moléculas de Adhesión Celular/química , Chlorocebus aethiops , Clonación Molecular , ADN Complementario/genética , Genes Protozoarios/genética , Intrones/genética , Datos de Secuencia Molecular , Peso Molecular , Unión Proteica , Proteínas Recombinantes de Fusión/metabolismo , Análisis de Secuencia de ADN , Homología de Secuencia de Aminoácido , Toxoplasma/metabolismo , Células VeroRESUMEN
Pulsed field gel electrophoresis (PFGE) was used to separate chromosome-sized DNA from two species of microsporidia of fishes. The molecular karyotype of Glugea atherinae exhibits 16 DNA bands from 420 to 2,700 kb, and that of Spraguea lophii 12 bands from 230 to 980 kb. Until now they represent respectively the largest and the smallest genomes visualized for microsporidia: 19.5 Mb for G. atherinae and 6.2 Mb for S. lophii (the smallest nuclear genome in eukaryotic organism). We have analysed separately five strains of G. atherinae (individual cysts), with this technique. The electrophoretic spectra are the same for these strains, except for the absence of the 2,380-kb band in one case. Therefore, the karyotype seems to be rather well conserved for this species.