The mitogenome of Onchocerca volvulus from the Brazilian Amazonia focus

We report here the first complete mitochondria genome of Onchocerca volvulus from a focus outside of Africa. An O. volvulus mitogenome from the Brazilian Amazonia focus was obtained using a combination of highthroughput and Sanger sequencing technologies. Comparisons made between this mitochondrial genome and publicly available mitochondrial sequences identified 46 variant nucleotide positions and suggested that our Brazilian mitogenome is more closely related to Cameroon-origin mitochondria than West African-origin mitochondria. As well as providing insights into the origins of Latin American onchocerciasis, the Brazilian Amazonia focus mitogenome may also have value as an epidemiological resource.

RELAÇÕES SOLO–VEGETAÇÃO EM “ILHAS” FLORESTAIS SAVANAS ADJACENTES, NO NORDESTE DE RORAIMA

Studies on soils of forest islands within the savanna domain are key for understanding processes of landscape formation and evolution. We characterized the morphological, physical and chemical properties of soils at four different forest fragments that occur in the savanna-forest mosaic of northeastern Roraima, north Amazonia. The methodology was based on transects crossing the entire island, from east-west and northsouth direction, digging up five soil profiles for sampling and classification. In addition, the neighboring savannas were also sampled following the same strategy, at 100 m long transects departing from the border, allowing comparisons to be made. Latosols were the dominant soil class in all four islands, followed by Ultisols and Plinthosols. All soils were dystric, with low CEC and acid. Better chemical and physical conditions were observed in forested soils compared with surrounding savannas, in a given soil class. Thus, in spite of no variation on soil class at different phytophysionomies at a given gradient, specific chemical and physical attributes were significantly varied, exerting a positive effect for the establishment of forest vegetation. Despite their occurrence side-by-side in the savanna-forest mosaic, the present-day climate agrees with the existence of savanna in the flat landforms, whereas forest islands are conditioned by subtle, yet significant, soil physico-chemical variations, with no need to invoke any paleoclimate for explaining this relationship. Further in depth studies may contribute for testing the hypothesis that Quaternary shifts of the expansion and contraction of forest may represent paleoclimate relicts isolated within the savanna domain.