The history of the introduction of the giant river prawn, Macrobrachium cf. rosenbergii (Decapoda, Palaemonidae), in Brazil: new insights from molecular data

The giant river prawn, Macrobrachium cf. rosenbergii, is one of the most cultivated freshwater prawns in the world and has been introduced into more than 40 countries. In some countries, this prawn is considered an invasive species that requires close monitoring. Recent changes in the taxonomy of this species (separation of M. rosenbergii and M. dacqueti) require a re-evaluation of introduced taxa. In this work, molecular analyses were used to determine which of these two species was introduced into Brazil and to establish the geographic origin of the introduced populations that have invaded Amazonian coastal waters. The species introduced into Brazil was M. dacqueti through two introduction events involving prawns originating from Vietnam and either Bangladesh or Thailand. These origins differ from historical reports of the introductions and underline the need to confirm the origin of other exotic populations around the world. The invading populations in Amazonia require monitoring not only because the biodiversity of this region may be affected by the introduction, but also because admixture of different native haplotypes can increase the genetic variability and the likelihood of persistence of the invading species in new habitats.

Genetic characterization of native and introduced populations of the neotropical cichlid genus Cichla in Brazil

A molecular phylogenetic analysis based on mitochondrial 16S ribosomal DNA and Control Region sequences from native and introduced populations was undertaken, in order to characterize the introduction of Cichla (peacock bass or tucunaré) species in Brazil. Mitochondrial DNA haplotypes found in introduced fish from Minas Gerais state (southeastern Brazil) clustered only with those from native species of the Tocantins River (Cichla piquiti and C. kelberi), thereby suggesting a single or, at most, few translocation acts in this area, even though with fish from the same source-population. Our study contributes to an understanding of the introduction of Cichla in regions of Brazil outside the Amazon basin, and adds phylogenetic data to the recently describe Cichla species, endemic from the Tocantins-Araguaia basin.

Identification and phylogenetic inferences on stocks of sharks affected by the fishing industry off the Northern coast of Brazil

The ongoing decline in abundance and diversity of shark stocks, primarily due to uncontrolled fishery exploitation, is a worldwide problem. An additional problem for the development of conservation and management programmes is the identification of species diversity within a given area, given the morphological similarities among shark species, and the typical disembarkation of processed carcasses which are almost impossible to differentiate. The main aim of the present study was to identify those shark species being exploited off northern Brazil, by using the 12S-16S molecular marker. For this, DNA sequences were obtained from 122 specimens collected on the docks and the fish market in Bragança, in the Brazilian state of Pará. We identified at least 11 species. Three-quarters of the specimens collected were either Carcharhinus porosus or Rhizoprionodon sp, while a notable absence was the daggernose shark, Isogomphodon oxyrhyncus, previously one of the most common species in local catches. The study emphasises the value of molecular techniques for the identification of cryptic shark species, and the potential of the 12S-16S marker as a tool for phylogenetic inferences in a study of elasmobranchs.

Low levels of genetic diversity depicted from mitochondrial DNA sequences in a heavily exploited marine fish (Cynoscion acoupa, Sciaenidae) from the Northern coast of Brazil

The acoupa weakfish (Cynoscion acoupa - Sciaenidae) is a marine species of croaker with estuarine-dependent behavior, found in the western Atlantic from Panama to Argentina. It is one of the most exploited food fish on the northern coast of Brazil. In this study, DNA sequences were determined from the entire control region (D-loop) of the mitochondrial genome of 297 individuals collected during seven different months between December 2003 and August 2005 on the northern coast of Brazil (Amapá and Pará). Genetic variability expressed by haplotype (h = 0,892) and nucleotide (p = 0,003) diversities were low compared to other heavily exploited marine fish species from the western Atlantic and eastern Asia. AMOVA depicted a lack of genetic structuring among the samples from different years, indicating the presence of a single stock of C. acoupa within the sample area. The possible reasons for the low levels of genetic diversity are discussed. These results demonstrate a need for the monitoring of C. acoupa harvesting and the preservation of the estuaries within its geographic range, considering that this large fish depends on estuarine ecosystems during part of its life cycle.

Sciaenidae fish of the Caeté River estuary, Northern Brazil: mitochondrial DNA suggests explosive radiation for the Western Atlantic assemblage

Sciaenids are fish which are normally abundant in tropical estuaries of the western Atlantic. Studies on the Caeté river estuary in the northern Brazilian state of Pará have revealed that in this area Sciaenidae is the dominant family, comprising almost 50% of all teleosts sampled. In this paper we present the results of the first phylogenetic study on South American estuarine sciaenids, during which we obtained mitochondrial gene 16S sequences from 15 species belonging to eight genera occurring in the Caeté estuary. Intergeneric nucleotide divergences varied from 5 to 15%, Lonchurus and Menticirrhus being the most divergent lineages. Nucleotide divergences were quite variable amongst species of the same genus, ranging from 1.2% (Stellifer microps x Stellifer naso) to 8.4% (Menticirrhus americanus x Menticirrhus littoralis). Cladograms based on maximum parsimony, minimum evolution and maximum likelihood depicted an explosive diversification pattern for the western Atlantic sciaenid assemblage. Our analysis further reveals a very close relationship between Bairdiella and Stellifer, a monophyletic clade which emerged during the more recent diversification events of the Sciaenidae family. The phylogenetic reconstruction suggests the need for a revision of the taxonomy and nomenclature of the Bairdiella/Stellifer group.

Population analysis of Scomberomorus cavalla (Cuvier, 1829) (Perciformes, Scombridae) from the Northern and Northeastern coast of Brazil

Scomberomorus cavalla é uma espécie de peixe pelágico amplamente distribuído na costa oeste do Atlântico, e uma diminuição no seu nível de captura tem sido verificada nos E.U.A e Golfo do México, comparada com os níveis alcançados pela espécie no passado. Da mesma forma, em algumas áreas do Brasil, há indícios de sobre-exploração. Entretanto, não existem estudos moleculares que visam o manejo deste importante item. Desta forma, no presente estudo, foram seqüenciados 380 pares de bases nucleotídicas da região da Alça-D do DNA mitocondrial de amostras provenientes de desembarque em Macapá, Bragança e Fortaleza. As análises filogenéticas e populacionais revelaram que há apenas uma população panmítica e baixos níveis de variabilidade genética foram observados. Estes resultados, assim como a observada sobre-exploração de S. cavala, representam dados muito importantes para o estabelecimento do manejo deste estoque a fim de prevenir um colapso ou risco de extinção no futuro.

Reference range for T lymphocytes populations in blood donors from two different regions in Brazil

ABSTRACT: This study defined the normal variation range for different subsets of T-lymphocyte cells count in two different Brazilian regions. We analysed the T-lymphocytes subpopulations (CD3+, CD4+, CD8+) in blood donors of two Brazilian cities, located in North (Belem, capital state of Para, indian background) and Northeast (Salvador, capital state od Bahia, African background) regions of Brazil. Results were compared according to gender, stress level (sleep time lower than 8 hours/day), smoking, and alcohol intake. Lymphocytes subpopulations were measured by flow cytometry. Five hundred twenty-six blood donors from two Brazilians cities participated in the study: 450 samples from Bahia and 76 samples from Pará. Most (60%) were men, 59% reported alcohol intake, 12% were smokers, and 80% slept at least 8 h/day. Donors from Bahia presented with significantly higher counts for all parameters, compared with Para. Women had higher lymphocytes levels, in both states, but only CD4+ cells count was significantly higher than men's values. Smokers had higher CD4+ counts, but sleep time had effect on lymphocytes levels only for Para's donors (higher CD3+ and CD4+ counts). That state had also, a higher proportion of donors reporting sleep time <8 h/day. The values for CD3, CD4 and CD8+ cells count were significantly higher in blood donors from Bahia than among those from Pará. Female gender, alcohol intake, stress level, and smoking were associated with higher lymphocyte counts. The use of a single reference range for normal lymphocytes count is not appropriate for a country with such diversity, like Brazil is.

Identification of duplicates of cassava accessions sampled on the North Region of Brazil using microsatellite markers

Duplicatas costumam ocorrer em bancos de germoplasma e a sua identificação é necessária para facilitar o manejo dos bancos ativos de germoplasma (BAGs) e diminuir custos de manutenção. O objetivo deste trabalho foi identificar duplicatas de mandioca determinadas previamente pela caracterização morfo-agronômica, em um BAG da Amazônia Oriental. Foram selecionados 36 acessos que se agrupavam em 13 grupos de similaridade morfo-agronômica para serem genotipados com 15 locos microssatélites. Todos os locos foram polimórficos, sendo obtidos 75 alelos, com média de cinco alelos por loco e H_E = 0,66. Foram encontrados 34 pares de genótipos que apresentaram perfis multilocos idênticos e a probabilidade de identidade genética foi de 1,1x10^-12 com probabilidade de exclusão de 99,9999%. Entre essas duplicatas, estão materiais coletados em épocas e locais diferentes, e com diferentes denominações e acessos com o mesmo nome coletados em diferentes locais e anos. O estudo identificou genótipos que vem sendo cultivados em diferentes locais e que vêm sendo mantidos pelos agricultores ao longo dos anos.

Cytogenetic studies in six species of Scinax (Anura, Hylidae) clade Scinax ruber from northern and northeastern Brazil

Scinax species are still underrepresented in cytogenetic studies, mainly with respect to populations from northeastern and northern Brazil. In this study, we provide new chromosomal information on Scinax boesemani, S. camposseabrai, S. garbei, S. pachycrus, S. trilineatus and S. x-signatus, all belonging to clade S. ruber. They were collected at two locations in the Caatinga biome (northeastern Brazil) and at one in the Amazon (northern Brazil) biomes. Chromosomes were analyzed by conventional staining, C-banding, Ag-NOR staining, and fluorochrome staining. All species shared a modal diploid value of 2n = 24 and fundamental arm number (FN) of 48. Moreover, both chromosomal size and morphology were similar to other species in this Scinax clade. C-banding revealed centromeric heterochromatin in all species, along with terminal species-specific C-bands in some species. Active nucleolar organizer regions (Ag-NORs) were identified at 11q in most species, except for S. boesemani and S. garbei (Ag-NORs at interstitial region of 8q). Differing from most anurans, GC-rich regions were not restricted to NORs, but also coincident with some centromeric and terminal C-bands. These data contribute to the cytotaxonomy of Scinax by providing chromosomal markers and demonstrating the occurrence of microstructural rearrangements and inversions on chromosomal evolution of Scinax.