Concordance of Giardia duodenalis assemblages determined by different PCR methodologies in three observational studies in Cuba

Giardia duodenalis is one of the most important intestinal parasites globally, especially in children, and in Cuba is the leading cause of chronic paediatric diarrhoea in this population. G. duodenalis is composed of eight genetic groups (or assemblages), two of which (A and B) are apparently zoonotic, occurring in both humans and other animals. However, consensus on the most appropriate genotyping scheme for optimal characterization of G. duodenalis isolates is lacking. In this article we present the results of three descriptive observational studies conducted in Havana, Cuba between 2010 and 2013, with the aim of comparing the results from molecular (PCR) approaches targeting different genes in order to assign with confidence 224 isolates of G. duodenalis to the correct assemblages. In each sub-study, following DNA isolation by the phenol/chloroform/isoamyl alcohol extraction method, PCR targeting the triose phosphate isomerase (tpi) gene was used for molecular characterization, as well as one additional PCR-method targeting another gene or pair of genes. DNA amplification was obtained in 87%, 83%, and 80% in the three sub-studies. Although excellent agreement (kappa index = 1) was recorded between results from some pairs of genes, for other combinations only moderate or substantial agreement was achieved. These results highlight the importance of interpretation of genotyping data, especially when single genetic markers are used. From the results of our studies, PCR targeting a combination of the tpi gene and the intergenic spacer region of rDNA may be a useful approach for the molecular characterization of G. duodenalis isolates

Efeito do sombreamento no crescimento inicial de Lonchocarpus muehlbergianus Hassl

Foi realizado experimento em casa de vegetação para verificar a influência do sombreamento no desenvolvimento de plantas de Lonchocarpus muehlbergianus. Foram utilizados os níveis de sombreamento de 40 e 60% com tela de sombrite de cor preta e o nível de 0%, com luminosidade total. Foram obtidos os seguintes resultados: as plantas cultivadas em 40 e 60% de sombreamento apresentaram as maiores médias de altura e área foliar. Os maiores valores de diâmetro do colo e da raiz principal e de peso da matéria seca da parte aérea e do sistema radicular foram observados nas plantas sob 0 e 40% de sombreamento.This experiment was carried out under greenhouse conditions to verifiy the influence of shading on the growth of Lonchocarpus muehlbergianus plants. The following shading levels were used: 40% and 60% obtained using black plastic screening, and 0% under full light. The following results were obtained: the plants cultivated in 60% shading were higher and present larger leaf areas, wider collar and main root diameters, besides larger aerial and dry root weight were obtained in plants cultivated in 0% and 40% shading.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Improved purification and enzymatic properties of a mixture of Sticholysin i and II: Isotoxins with hemolytic and phospholipase A2 activities from the sea anemone Stichodactyla helianthus

Sticholysin I and Sticholysin II (StI and StII) are two potent hemolysins which form pores in natural and model membranes at nanomolar concentrations. These proteins were purified from the aqueous extract of the sea anemone Stichodactyla helianthus, Ellis 1768, by gel filtration and ionic exchange chromatography. This procedure rendered StI and StII with high purity (purification factors: 36 and 50, respectively) but a low yield of hemolytic activity, HA (95%, with an increase in specific activity: 14 times) from the animal extract using an oxidized phospholipid-based affinity chromatographic matrix binding phospholipases. Cytolysin identification in the mixture was performed by immunoblotting and N-terminal sequence analyses. Phospholipase A2 (PLA2) activity of StI–StII was relatively high (1.85 U/mg) and dependent of Ca2+. The activity resulted optimum when was measured with the mostly unsaturated soybean phosphatidylcholine (PC), when compared to the less unsaturated egg PC or completely saturated dipalmitoyl PC, in the presence of 40 mM Ca2+ at pH 8.0. This Ca2+ concentration did not exert any effect on binding of StI–StII with soybean PC monolayers. Then, PLA2 activity seems not be required to binding to membranes.The authors wish to thank INFORMATICA ddmm, Bergamo, Italy and CYTED (ENZNUT network 108RT0346), for kindly provided financial support to A. del Monte, and thanks to Havana University, Cuba, and CONACyT, México, for scientific grants.Peer Reviewe