ABSTRACT
A variety of host immunogenetic factors appear to influence both an individual's susceptibility to infection with Mycobacterium leprae and the pathologic course of the disease. Animal models can contribute to a better understanding of the role of immunogenetics in leprosy through comparative studies helping to confirm the significance of various identified traits and in deciphering the underlying mechanisms that may be involved in expression of different disease related phenotypes. Genetically engineered mice, with specific immune or biochemical pathway defects, are particularly useful for investigating granuloma formation and resistance to infection and are shedding new light on borderline areas of the leprosy spectrum which are clinically unstable and have a tendency toward immunological complications. Though armadillos are less developed in this regard, these animals are the only other natural hosts of M. leprae and they present a unique opportunity for comparative study of genetic markers and mechanisms associable with disease susceptibility or resistance, especially the neurological aspects of leprosy. In this paper, we review the recent contributions of genetically engineered mice and armadillos toward our understanding of the immunogenetics of leprosy.
Subject(s)
Animals , Mice , Animals, Genetically Modified , Armadillos/genetics , Disease Models, Animal , Immunogenetic Phenomena/immunology , Leprosy/genetics , Leprosy/immunology , Mycobacterium leprae , Mice/genetics , Armadillos/microbiology , Mycobacterium leprae/genetics , Mycobacterium leprae/immunologyABSTRACT
Para este estudo foi sequenciado o gene mitocondrial Citocromo b (1140pb) em amostras de ADN de 12 exemplares de Euphractus sexcinctus e 67 exemplares de Dasypus novemcinctus. Análises filogenéticas (distância, máxima parcimônia e máxima vesossimilhança) e populacionais (median-joining) foram realizadas com objetivo de estudar a variação genética e a filogeografica destas duas espécies. Também foi avaliada a posição filogenética de outros Dasypodidae (Dasypus kappleri, Cabassous unicinctus, C. tatouay e Tolypeutes tricinctus). Os resultados confirmaram a monofilia de Dasypodidae, Dasypodinae, Euphractinae e Tolypeutinae, assim como a relação maior entre as duas últimas sub-famílias. Em E. sexcinctus foram identificados 11 haplótipos e em D. novemcinctus 49. As análises mostraram o alto polimorfismo do gene Citocromo b, a falta de estruturação genética das populações, uma baixa divergência genética (distância p) entre os haplótipos e mostraram que o Rio São Francisco não constitui uma barreira ao fluxo gênico nestas duas espécies, uma vez que o mesmo haplótipo ocorreu em suas duas margens. Três haplótipos de E. sexcinctus formaram em todas as análises um grupo que se distribui na região da Caatinga do extremo nordeste do Brasil, ao norte do Rio São Francisco. As análises mostraram quatro grupos entre os haplótipos de D. novemcinctus (49 deste estudo e 26 do Genbank), com uma clara separação entre o haplótipo norte-americano de todos os demais sul-americanos. Entre os sul-americanos existem três grupos, um formado por 65 haplótipos que se distribuem no Brasil, Argentina e Paraguai. Os outros dois grupos são menores, um ocorrendo na região Norte do Brasil (Amazonas e Pará) com três haplótipos e outro formado por seis haplótipos que ocorrem na Bahia, Rio de Janeiro e Rondônia. Embora suas características morfológicas sejam compatíveis com as descrições de D. novemcinctus, exemplares destes dois últimos grupos mostraram diferenças morfológicas em seus crânios...
DNA samples of 12 specimens of Euphractus sexcinctus and 67 specimens of Dasypys novemcinctus had the mitochondrial gene Cytochrome b (1140pb) amplified and sequenced. Phylogenetic (distance, maximum parsimony and maximum likelihood) and population (median-joining) analyses were carried out in order to study the genetic variation and phylogeography of these two species. It was also assessed the phylogenetic position of other Dasypodidae: Dasypus kappleri, Cabassous unicinctus, C. tatouay and Tolypeutes tricinctus. The results confirmed the monophyly of Dasypodidae, Dasypodinae, Euphractinae and Tolypeutinae, as well as the relationship between the two largest sub-families. In E. sexcinctus 11 haplotypes and in D. novemcinctus 49, were identified. The analyses showed the high polymorphism of the gene Cytochrome b, a lack of population genetic structure, a low genetic divergence (p distance) between haplotypes and that Rio São Francisco is not a barrier to gene flow in these two species, once the same haplotype occur in both margins. Three haplotypes of E. sexcinctus formed, in all analyses, a group that is distributed in the region of Caatinga, the extreme northeastern Brazil, north of Rio São Francisco. Analyses were congruent in showing four groups among D. novemcinctus haplotypes (49 of this study and 26 of Genbank), with a clear separation between United States haplotype and all other South American ones. Among South American haplotypes there are three groups, one is formed by 65 haplotypes distributed in Brazil, Argentina and Paraguay. The other two groups are smaller, one occurring in northern Brazil (Para and Amazonas) with three haplotypes, and another formed by six haplotypes occurring in Bahia, Rio de Janeiro and Rondônia. Although morphologic characteristics are compatible with the descriptions of D. novemcinctus, the latter two groups showed some morphologic differentiation in their skulls that corroborate molecular data and suggest...
Subject(s)
Animals , Phylogeography , Cytochromes b/analysis , DNA, Mitochondrial/analysis , Genetic Variation , Phylogeny , Polymorphism, Genetic , Species Specificity , Armadillos/geneticsABSTRACT
Spermatocytes from the two armadillo species, C. villosus and D. hybridus were studied in microspreads for synaptonemal complexes (SCs) and in thin sections for electron microscopy (EM). The complete se karyotype generally agrees with previous reports on mitotic chromosomes, except for the sex chromosomes. The X chromosome is submetacentric in both species and the Y is the shortest one in C. villosus and the second shortest in D. hybridus, and an extremely acrocentric one. A SC is formed along the total length of the Y chromosome, and this SC persists along all the pachytene substages. A single recombi-nation nodule (RN) is located in the region of the se nearest to the attachment to the nuclear envelope. The lateral element (LE) of the X axis in the SC shows a wavy aspect in most of the se length distant from the nuclear envelope. Nucleoli are attached to acrocentric or submetacentric bivalents, are visibly double in some cells , and in thin sections show an elaborate nucleolonema. Some differences in the XY are species-specific, as the higher degree of tangling and stronger heteropycnosis in D. hybridus. The effective, single crossover of the XY pair is highly localized, despite the permanence of a long tract of SC