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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Variação sazonal do potencial da água nas folhas de cafeeiro em Mococa, SP Seasonal changes in coffee leaf water potential in Mococa, São Paulo State, Brazil

Para avaliar o potencial da água nas plantas de Coffea arabica L., foi desenvolvido um experimento em Mococa (SP), de agosto de 2005 a julho de 2006, com as cultivares Mundo Novo (MN), Obatã (OB) e Ouro-Verde (OV). As cultivares OB e OV tinham oito anos de idade, e as plantas do MN haviam sido recepadas há cinco anos. Os espaçamentos entre as plantas de MN, OB e OV foram de 3,6 x 1,0 m; 2,5 x 1,0 m e 3,5 x 0,74 m respectivamente. As avaliações dos potenciais da água das plantas na antemanhã (&#968;am) foram realizadas a cada duas semanas. O potencial da água na folha durante o período diurno (&#968;a) foi medido no final de abril. Os dados de &#968;am na folha variaram em função da quantidade de água no solo, com as oscilações decorrentes da precipitação pluvial sazonal. Os valores de &#968;am foram de -1,29; -1,60 e -1,68 MPa nos meses de estiagem e -0,06; -0,07 e -0,07 MPa nos meses de maiores precipitações para MN, OB e OV respectivamente. Esses valores são importantes para caracterizar o estado hídrico das folhas do cafeeiro ao longo do ano agrícola, visto que o período de estresse hídrico coincidiu com a fase de indução (fevereiro a junho) e maturação das gemas florais, bem como o período de maiores volumes de precipitação pluvial com a granação e maturação dos frutos.<br>In order to assess the xylem water potential in Coffea arabica L. plants, a field experiment was carried out in Mococa, São Paulo State, Brazil, from August 2005 to July 2006 with the following cultivars: Mundo Novo (MN), Obatã (OB) and Ouro-Verde (OV). The OB and OV cultivars were eight years old, and MN plants had been topped five years ago. Spacing among the plants were 3.6 x 1.0 m, 2.5 x 1.0 m and 3.5 x 0.75 m, respectively. Predawn leaf water potential (&#968;am) was measured each 15 days. Xylem water potential along the day (&#968;a) was measured at the end of April. Data concerning leaf &#968;am varied according to the soil water profile as affect by seasonal rainfall. &#968;am values were -1.29, -1.60 and -1.68 MPa during dry months and -0.06, -0.07 and -0.07 MPa during months of greater precipitations for MN, OB and OV, respectively. These values were important and relevant to Arabic coffee cultivars in order to characterize plant water status along the year, because the period of water stress was coincident with the phase of induction (February at June) and maturation of flowering buds; and the period of greater rainfall with the phase of grain filling and fruit maturation

Macroscopic description of the external and middle ear of paca (Cuniculus paca Linnaeus, 1766)

Abstract: Paca (Cuniculus paca), one of the largest rodents of the Brazilian fauna, has inherent characteristics of its species which can conribute as a new option for animal experimantation. As there is a growing demand for suitable experimental models in audiologic and otologic surgical research, the gross anatomy and ultrastructural ear of this rodent have been analyzed and described in detail. Fifteen adult pacas from the Wild Animals Sector herd of Faculdade de Ciências Agrárias e Veterinárias, Unesp-Jaboticabal, were used in this study. After anesthesia and euthanasia, we evaluated the entire composition of the external ear, registering and ddescribing the details; the temporal region was often dissected for a better view and detailing of the tympanic bulla which was removed and opened to expose the ear structures analyzed mascroscopically and ultrastructurally. The ear pinna has a triangular and concave shape with irregular ridges and sharp apex. The external auditory canal is winding in its path to the tympanic mebrane. The tympanic bulla is is on the back-bottom of the skull. The middle ear is formed by a cavity region filled with bone and membranous structures bounded by the tympanic membrane and the oval and round windows. The tympanic membrane is flat and seals the ear canal. The anatomy of the paca ear is similar to the guinea pig and from the viewpoint of experimental model has major advantages compared with the mouse ear