Cell Biology

Abstract

Giardia lamblia is an intestinal parasite of several mammals. It is a parasitic protozoan that infects thousands of people all over the world, causing a disease known as giardiasis. Giardia possesses several cytoskeletal structures composed of microtubules, such as the disc, median body, axonemes of eight flagella and the funis. The median body is formed by an irregular set of microtubules situated dorsally to the caudal axonemes, resembling a comma in a face.In the present study we have used a new technique that allows the removal of the plasma membrane using detergents and observation of cytoskeletal structures by either conventional scanning electron microscopy or field emission scanning electron microscopy (FESEM). Cells were adhered to poly-L-lysine-coated glass coverslips and then treated with the permeabilization buffer (0.5% Nonidet-40 P-40, 0.1M Pipes, 1mM MgSO 4 , 2 mM glycerol, 2 mM EGTA, 1 mM PMSF (phenylmethylsulfonyl fluoride), 0.5% Triton X-100) for different times (10 min-2 h). The cells were washed, fixed in 2.5% glutaraldehyde, post-fixed 1% OsO 4 , dehydrated, critical point dried and coated with gold. The samples were examined in a Jeol JSM-6340F Field Emission or JSM-5800 Scanning Electron Microscope. Upon these procedures the median body was better visualized. When the plasma membrane was completely extracted the median body was not visualized suggesting the connection between these two cells structures. FESEM revealed that the median body was constituted by several small fascicles formed by microtubules forming larger bundles. The bundle number was variable as well the microtubules number found in each fascicle. There was a variation in number, disposition and location of the median body fascicles in different organisms found in the same culture preparation. Each fascicle was formed by parallel microtubules with different lengths, but the different fascicles were not parallel. Some fascicles were connected, leading a misunderstanding by light microscopy of the presence of one or two median bodies. In the caudal axonemes region a thicker median body bundle is seen. In conclusion, there are not two median bodies, and they were present in about 70% of the cells population, with connections with the ventral disc.Supported by CNPq, FAPERJ, PRONEX and AUSU. The authors thank the technical support of William Christian Molêdo Lopes and the Laboratório de Ultraestrutura Celular Hertha Meyer (UFRJ) for the use of the FESEM. BC2 -MYCOPLASMA OBSERVATIONS IN TRICHOMONAS VAGINALIS: THE ENEMY WITHIN.Vancini, R.G 1 . & Benchimol, M 2 1 Programa de Ciências Morfológicas, Universidade Federal do Rio de Janeiro, RJ, Brasil. 2 Laboratório de Ultraestrutura Celular, Universidade Santa Úrsula, RJ, Brasil.The protist Trichomonas vaginalis is a well described early eukaryote and its infection is the most prevalent nonviral sexually transmitted disease worldwide. In recent studies it has been proposed that Trichomonads presents different infectious organisms within the cell such as, virus like particles and bacter...