RESUMO
Isoenzyme-based studies have identified 3 taxa/species/'phylogenetic complexes' as agents of visceral leishmaniasis in Sudan: L. donovani, L. infantum and "L. archibaldi". However, these observations remain controversial. A new chitinase gene phylogeny was constructed in which stocks of all 3 putative species isolated in Sudan formed a monophyletic clade. In order to construct a more robust classification of the L. donovani complex, a panel of 16 microsatellite markers was used to describe 39 stocks of these 3 species. All "L. donovani complex" stocks from Sudan were again found to form a single monophyletic clade. L. donovani ss stocks from India and Kenya were found to form 2 region-specific clades. The partial sequence of the glutamate oxaloacetate transaminase (GOT) gene of 17 L. donovani complex stocks was obtained. A single nucleotide polymorphism in the GOT gene appeared to underlie the isoenzyme classification. It was concluded that isoenzyme-based identification is unsafe for stocks isolated in L. donovani endemic areas and identified as L. infantum. It was also concluded that the name L. archibaldi is invalid and that only a single visceralizing species, Leishmania donovani, is found in East Africa.
Assuntos
Aspartato Aminotransferase Mitocondrial/genética , Leishmania donovani/classificação , Leishmania donovani/enzimologia , Leishmaniose Visceral/parasitologia , África Oriental , Animais , Aspartato Aminotransferase Mitocondrial/química , DNA de Protozoário/química , DNA de Protozoário/genética , Humanos , Índia , Isoenzimas/genética , Leishmania donovani/genética , Repetições de Microssatélites/genética , Filogenia , Reação em Cadeia da Polimerase , Polimorfismo de Nucleotídeo Único/genética , Análise de Sequência de DNARESUMO
The investigation of microsatellite markers has recently superseded that of isoenzymes for many population-biology applications. Microsatellites have the advantages of being dominant, neutral, highly polymorphic and easily scored by high-throughput methods. However, it is necessary to develop a new panel of markers for each group of organisms of interest. Previously, only about 5% of the markers that amplify Leishmania major microsatellite loci were also found to amplify L. donovani loci. A panel of 20 microsatellite markers that are polymorphic in L. donovani and L. infantum has now been developed, using a rapid-enrichment method that will be suitable for developing libraries of markers for other trypanosomatid species. This is the first panel of polymorphic microsatellite markers, to be isolated de novo from any species of Leishmania, that is large enough for population-biology applications.
Assuntos
Leishmania donovani/classificação , Repetições de Microssatélites , Alelos , Animais , DNA de Protozoário/genética , Humanos , Leishmania donovani/genética , Parasitologia/métodos , Polimorfismo GenéticoRESUMO
In addition to the common features of spermiogenesis in Reptilia, new structures are seen in Agama adramitana that have not been described in previous studies. Two acrosomal granules are observed in the acrosomal vesicle. The posterior acrosomal granule differentiates as an anterior electron-dense material in the acrosome, and the anterior one forms a posterior translucent component of the acrosome. Also, the subacrosomal granule spreads in the subacrosomal space as a subacrosomal nuclear cap.