Comparação entre métodos de extração e purificação de aflatoxinas em amendoim.

O objetivo do trabalho foi comparar dois métodos de extração e purificação das aflatoxinas B1, G1, B2 e G2 em amendoim. O primeiro método envolveu a extração das aflatoxinas com acetonitrila seguida de purificação através de colunas de separação por fase sólida e o segundo consistiu de extração em metanol e purificação em colunas de imunoafinidade. Foram realizados ensaios de recuperação com amostras fortificadas em dois diferentes níveis: 6,13 μg/kg e 12,25 μg/kg de aflatoxinas totais. O primeiro método apresentou valores de recuperação dentro da faixa aceitável para ambos os níveis de contaminação. O segundo método apresentou elevadas percentagens de recuperação para o nível mais baixo de contaminação, exceto para a aflatoxina G2. Entretanto, no nível mais alto de contaminação, a recuperação ficou abaixo da faixa aceitável. Desse modo, o primeiro método revelou-se mais eficiente para a análise de aflatoxinas em amendoim por cromatografia líquida e detecção por fluorescência

Visualizing the 3D Architecture of Multiple Erythrocytes Infected with Plasmodium at Nanoscale by Focused Ion Beam-Scanning Electron Microscopy

Different methods for three-dimensional visualization of biological structures have been developed and extensively applied by different research groups. In the field of electron microscopy, a new technique that has emerged is the use of a focused ion beam and scanning electron microscopy for 3D reconstruction at nanoscale resolution. The higher extent of volume that can be reconstructed with this instrument represent one of the main benefits of this technique, which can provide statistically relevant 3D morphometrical data. As the life cycle of Plasmodium species is a process that involves several structurally complex developmental stages that are responsible for a series of modifications in the erythrocyte surface and cytoplasm, a high number of features within the parasites and the host cells has to be sampled for the correct interpretation of their 3D organization. Here, we used FIB-SEM to visualize the 3D architecture of multiple erythrocytes infected with Plasmodium chabaudi and analyzed their morphometrical parameters in a 3D space. We analyzed and quantified alterations on the host cells, such as the variety of shapes and sizes of their membrane profiles and parasite internal structures such as a polymorphic organization of hemoglobin-filled tubules. The results show the complex 3D organization of Plasmodium and infected erythrocyte, and demonstrate the contribution of FIB-SEM for the obtainment of statistical data for an accurate interpretation of complex biological structures

Volutin Granules of Eimeria Parasites are Acidic Compartments and Have Physiological and Structural Characteristics Similar to Acidocalcisomes

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)The structural organization of parasites has been the subject of investigation by many groups and has lead to the identification of structures and metabolic pathways that may represent targets for anti-parasitic drugs. A specific group of organelles named acidocalcisomes has been identified in a number of organisms, including the apicomplexan parasites such as Toxoplasma and Plasmodium, where they have been shown to be involved in cation homeostasis, polyphosphate metabolism, and osmoregulation. Their structural counterparts in the apicomplexan parasite Eimeria have not been fully characterized. In this work, the ultrastructural and chemical properties of acidocalcisomes in Eimeria were characterized. Electron microscopy analysis of Eimeria parasites showed the dense organelles called volutin granules similar to acidocalcisomes. Immunolocalization of the vacuolar proton pyrophosphatase, considered as a marker for acidocalcisomes, showed labeling in vesicles of size and distribution similar to the dense organelles seen by electron microscopy. Spectrophotometric measurements of the kinetics of proton uptake showed a vacuolar proton pyrophosphatase activity. X-ray mapping revealed significant amounts of Na, Mg, P, K, Ca, and Zn in their matrix. The results suggest that volutin granules of Eimeria parasites are acidic, dense organelles, and possess structural and chemical properties analogous to those of other acidocalcisomes, suggesting a similar functional role in these parasites.585416423Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ)US National Institutes of Health [AI-07965]Barbara and Sanford Orkin/Georgia Research Alliance ChairConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)US National Institutes of Health [AI-07965

Volutin Granules Of Eimeria Parasites Are Acidic Compartments And Have Physiological And Structural Characteristics Similar To Acidocalcisomes

The structural organization of parasites has been the subject of investigation by many groups and has lead to the identification of structures and metabolic pathways that may represent targets for anti-parasitic drugs. A specific group of organelles named acidocalcisomes has been identified in a number of organisms, including the apicomplexan parasites such as Toxoplasma and Plasmodium, where they have been shown to be involved in cation homeostasis, polyphosphate metabolism, and osmoregulation. Their structural counterparts in the apicomplexan parasite Eimeria have not been fully characterized. In this work, the ultrastructural and chemical properties of acidocalcisomes in Eimeria were characterized. Electron microscopy analysis of Eimeria parasites showed the dense organelles called volutin granules similar to acidocalcisomes. Immunolocalization of the vacuolar proton pyrophosphatase, considered as a marker for acidocalcisomes, showed labeling in vesicles of size and distribution similar to the dense organelles seen by electron microscopy. Spectrophotometric measurements of the kinetics of proton uptake showed a vacuolar proton pyrophosphatase activity. X-ray mapping revealed significant amounts of Na, Mg, P, K, Ca, and Zn in their matrix. The results suggest that volutin granules of Eimeria parasites are acidic, dense organelles, and possess structural and chemical properties analogous to those of other acidocalcisomes, suggesting a similar functional role in these parasites. © 2011 International Society of Protistologists.585416423Bakar, N.A., Klonis, N., Hanssen, E., Chan, C., Tilley, L., Digestive vacuole genesis and endocytic processes in the early intraerythrocytic stages of Plasmodium falciparum (2009) J. Cell. 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