Similarities among ectoparasite fauna of sigmodontine rodents: phylogenetic and geographical influences

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Circulation of Different Lineages of Dengue Virus 2, Genotype American/Asian in Brazil: Dynamics and Molecular and Phylogenetic Characterization

The American/Asian genotype of Dengue virus type 2 (DENV-2) was introduced into the Americas in the 80′s. Although there is no data showing when this genotype was first introduced into Brazil, it was first detected in Brazil in 1990. After which the virus spread throughout the country and major epidemics occurred in 1998, 2007/08 and 2010. In this study we sequenced 12 DENV-2 genomes obtained from serum samples of patients with dengue fever residing in São José do Rio Preto, São Paulo (SJRP/SP), Brazil, in 2008. The whole open reading frame or envelope sequences were used to perform phylogenetic, phylogeographic and evolutionary analyses. Isolates from SJRP/SP were grouped within one lineage (BR3) close to isolates from Rio de Janeiro, Brazil. Isolates from SJRP were probably introduced there at least in 2007, prior to its detection in the 2008 outbreak. DENV-2 circulation in Brazil is characterized by the introduction, displacement and circulation of three well-defined lineages in different times, most probably from the Caribbean. Thirty-seven unique amino acid substitutions were observed among the lineages, including seven amino acid differences in domains I to III of the envelope protein. Moreover, we dated here, for the first time, the introduction of American/Asian genotype into Brazil (lineage BR1) to 1988/89, followed by the introduction of lineages BR2 (1998-2000) and BR3 (2003-05). Our results show a delay between the introduction and detection of DENV-2 lineages in Brazil, reinforcing the importance and need for surveillance programs to detect and trace the evolution of these viruses. Additionally, Brazilian DENV-2 differed in genetic diversity, date of introduction and geographic origin and distribution in Brazil, and these are important factors for the evolution, dynamics and control of dengue. © 2013 Drumond et al.

Comparative cytogenetic analysis of some species of the Dendropsophus microcephalus group (Anura, Hylidae) in the light of phylogenetic inferences

Background: Dendropsophus is a monophyletic anuran genus with a diploid number of 30 chromosomes as an important synapomorphy. However, the internal phylogenetic relationships of this genus are poorly understood. Interestingly, an intriguing interspecific variation in the telocentric chromosome number has been useful in species identification. To address certain uncertainties related to one of the species groups of Dendropsophus, the D. microcephalus group, we carried out a cytogenetic analysis combined with phylogenetic inferences based on mitochondrial sequences, which aimed to aid in the analysis of chromosomal characters. Populations of Dendropsophus nanus, Dendropsophus walfordi, Dendropsophus sanborni, Dendropsophus jimi and Dendropsophus elianeae, ranging from the extreme south to the north of Brazil, were cytogenetically compared. A mitochondrial region of the ribosomal 12S gene from these populations, as well as from 30 other species of Dendropsophus, was used for the phylogenetic inferences. Phylogenetic relationships were inferred using maximum parsimony and Bayesian analyses.Results: The species D. nanus and D. walfordi exhibited identical karyotypes (2n = 30; FN = 52), with four pairs of telocentric chromosomes and a NOR located on metacentric chromosome pair 13. In all of the phylogenetic hypotheses, the paraphyly of D. nanus and D. walfordi was inferred. D. sanborni from Botucatu-SP and Torres-RS showed the same karyotype as D. jimi, with 5 pairs of telocentric chromosomes (2n = 30; FN = 50) and a terminal NOR in the long arm of the telocentric chromosome pair 12. Despite their karyotypic similarity, these species were not found to compose a monophyletic group. Finally, the phylogenetic and cytogenetic analyses did not cluster the specimens of D. elianeae according to their geographical occurrence or recognized morphotypes.Conclusions: We suggest that a taxonomic revision of the taxa D. nanus and D. walfordi is quite necessary. We also observe that the number of telocentric chromosomes is useful to distinguish among valid species in some cases, although it is unchanged in species that are not necessarily closely related phylogenetically. Therefore, inferences based on this chromosomal character must be made with caution; a proper evolutionary analysis of the karyotypic variation in Dendropsophus depends on further characterization of the telocentric chromosomes found in this group. © 2013 Medeiros et al.; licensee BioMed Central Ltd.

Pseudoplatystoma metaense and P. orinocoense (Siluriformes: Pimelodidae) from the Orinoco basin, Venezuela: cytogenetic and molecular analyses

The genus Pseudoplatystoma includes catfish species distributed throughout the fresh waters of South America. These species are important fisheries resources and play a significant ecological role due to their piscivorous and migratory habits. The taxonomy of this genus is still debated: traditionally, only three species have been recognised, but recently, this number was raised to eight. The validity of these eight morphospecies, however, was not confirmed by two subsequent molecular phylogenetic studies, which identified either five or four main clades. In this study, we focused on the two morphospecies restricted to the Orinoco basin, P. metaense and P. orinocoense, which have been assigned to either the same or different clades in previous studies. We carried out cytogenetic analyses to describe their unknown karyotypes and to look for cytotaxonomic markers. We also analysed their mitochondrial sequences in order to assign the sampled specimens to the previously identified molecular clades. The two presumptive species show similar karyotypes (2n=56, 42 biarmed and 14 uniarmed chromosomes) and cytogenetic features in terms of the constitutive heterochromatin distribution and the number and location of minor and major ribosomal genes. Thus, no species-specific chromosome markers could be identified. The analysis of cytochrome b and cytochrome oxidase I mitochondrial genes (carried out by retrieving all the mtDNA Pseudoplatystoma sequences available in GenBank) distributed the sampled specimens into two distinct molecular clades and confirmed the need to re-evaluate, by parallel morphological and molecular analyses, the monophyly of some lineages.

Genetic variability and phylogenetic aspects in species of the genus Macrobrachium

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Molecular and cytogenetic analyses of cryptic species within the Synbranchus marmoratus Bloch, 1795 (Synbranchiformes: Synbranchidae) grouping: species delimitations, karyotypic evolution and intraspecific diversification

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)