Population genetic structure of three species in the genus Astrocaryum G. Mey. (Arecaceae).

We assessed the level and distribution of genetic diversity in three species of the economically important palm genus Astrocaryum located in Pará State, in northern Brazil. Samples were collected in three municipalities for Astrocaryum aculeatum: Belterra, Santarém, and Terra Santa; and in two municipalities for both A. murumuru: Belém and Santo Antônio do Tauá and A. paramaca: Belém and Ananindeua. Eight microsatellite loci amplified well and were used for genetic analysis. The mean number of alleles per locus for A. aculeatum, A. murumuru, and A. paramaca were 2.33, 2.38, and 2.06, respectively. Genetic diversity was similar for the three species, ranging from HE = 0.222 in A. aculeatum to HE = 0.254 in A. murumuru. Both FST and AMOVA showed that most of the genetic variation was found within populations for all three species, but high genetic differentiation among populations was found for A. aculeatum. Three loci were not in Hardy-Weinberg equilibrium, with populations of A. paramaca showing a tendency for the excess of heterozygotes (FIS = -0.144). Gene flow was high for populations of A. paramaca (Nm = 19.35). Our results suggest that the genetic diversity within populations followed the genetic differentiation among populations due to high gene flow among the population. Greater geographic distances among the three collection sites for A. aculeatum likely hampered gene flow for this species.

Genetic variability analysis of Byrsonima crassifolia germplasm collected in Pará State using ISSR markers.

Native of the Amazon, the nanche (Byrsonima crassifolia) is a fruit cultivated by family farmers and used in cooking; as such, it represents an opportunity for regional agribusiness. The Embrapa Eastern Amazon set up an active germplasm bank (BAG) consisting of 22 accessions sampled in 11 municipalities of Pará State. Due to its economic potential, there is an interest to advance the genetic breeding program of this species. The aim of this study was to characterize the BAG nanche collection using inter-simple sequence repeat (ISSR) markers. Accessions were genotyped using 23 pre-selected ISSR primers resulting in 109 amplified polymorphic and 51 monomorphic bands. With eight polymorphic bands each, the most polymorphic primers were UBC 809 and UBC 848. An unweighted pair-group method with arithmetic average cluster analysis based on Jaccard's coefficient indicated that the individuals clustered into two distinct groups. Accessions Igarapé Açu-2 and Augusto Corrêa-Pl 1 were most similar. The genetic dissimilarity values ranged from 0.10 to 0.59. We conclude that the ISSR markers were efficient in detecting polymorphisms in the nanche accessions, and that it is possible to infer the genetic variability among accessions of the collection. This demonstrate the importance of using molecular markers in poorly studied species and the advantages that this information can bring to the genetic improvement of such species.

Genetic diversity in a germplasm bank of Oenocarpus mapora (Arecaceae).

Oenocarpus mapora is an Amazonian palm species commonly used by native populations for food and in folk medicine. We measured genetic variability, using RAPD markers, of material kept in a germplasm bank composed of accessions sampled from the Brazilian Amazon. These included 74 individuals from 23 accessions sampled from 9 localities in three States of the Brazilian Amazon. Jaccard genetic similarities were calculated based on 137 polymorphic bands, amplified by 15 primers. Dendrograms constructed based on the genetic similarities among individuals and sample localities demonstrated genetic separation of Acre State from the States of Amazonas and Pará. Two models in three hierarchical levels were considered for AMOVA: one considering the grouping of sampling sites in each state, and the other considering sampling sites in each subgroup formed by the dendrograms. The first model showed no significant genetic variation among states. On the other hand, genetic variation among subgroups was significant. In this model, the within-sample-site genetic diversity was 47.15%, which is considered to be low, since O. mapora is allogamous. By means of Bayesian analysis, the sample sites were clustered into five groups, and their distribution was similar to what we found in the dendrograms based on genetic similarity.

Report of the second International Symposium on molecular epidemiology in childhood leukaemia and embryonal tumorus rio de janeiro Brazil

The recent International Symposium on Molecular epidemiology in Embryonal Tumours and Paediatric Leukaemia was held on 4–6 March 2008 in Rio de Janeiro, Brazil. It proved a very productive meeting in which studies relating to genetics, therapeutical trials, identification of risk factors in acute leukaemia neuroblastoma and Wilms’ tumours were presented. Over 120 participants gathered for three days of fruitful discussions, including representatives of paediatrics, haematology, laboratory, epidemiology and pathology. Debates were held about strategies of applications of important biomarkers for clinical trials. Highlights of each of the scientific presentations are summarized below.

Leucemia M3 variante: aspectos clínicos e diagnósticos / M3 variant leukemia: clinical and diagnosis features

A leucemia promielocítica (LMA M3) representa em média 5-10// dos casos de leucemias melóides agudas (LMA) registrados na literatura, acometendo preferencialmente adultos jovens e cursando com comportamento clínico-biológico distinto, quando comparada com as demais LMA. Caracteriza-se por morfolofia particular das células blásticas (M3 na classificaçäo FAB), translocaçäo dos cromossomos 15 e 17, e coagulaçäo intravascular disseminada ao diagnóstico ou após início da quimioterapia . Dentro deste subgrupo säo observados dois subtipos morfológicos conhecidos como LMA M3 hipergranular e LMA M3 hipogranular ou variante. Os autores analisaram 19 casos de LMA M3, diagnosticados dentre 217 casos de LMA, em seus aspectos clínicos e laboratoriais, e observaram que o reconhecimento da LMA M3 variante, apesar de se basear geralmente apenas em dados citomorfológicos, näo tem sido feito corretamente em nosso meio. Dos oito casos recebidos no serviço dos autores para estudo, apenas quatro foram encaminhados com o diagnóstico correto de seus serviços de origem, sendo os outros quatro casos diagnosticados como leucemia mielomonocítica (LMA M4). A imunofenotipagem, como técnica diagnóstica complementar à citomorfologia, permite esclarecer, definitivamente, casos duvidosos. A classificaçäo correta se faz cada vez mais necessária devido a aspectos terapêuticos e prognósticos particulares das LMA M3, que, ao contrário das outras formas de LMA, têm sido tratadas näo só com drogas citotóxicas, mas também com agentes indutores de diferenciaçäo celular, com excelentes resultados