Our previous study has shown that the decorated tubules (collectively known as the decorated spongiome) of the contractile vacuole complex (CVC) in Paramecium are the site of fluid segregation, as the binding of microinjected monoclonal antibody (mAb) DS-1 to the tubules reduced the CVC's fluid output. In this study, we showed by immunogold labeling on cryosections that the antigenic sites for ...

Virions of the type 1 human immunodeficiency virus (HIV-1) can enter target cells by fusion or endocytosis, with sharply different functional consequences. Fusion promotes productive infection of the target cell, while endocytosis generally leads to virion inactivation in acidified endosomes or degradation in lysosomes. Virion fusion and endocytosis occur equally in T cells, but these pathways ...

Recent biochemical studies involving 2',7'-bis-(2-carboxyethyl)-5, 6-carboxylfluorescein (BCECF)-labeled saponin-permeabilized and parasitized erythrocytes indicated that malaria parasite cells maintain the resting cytoplasmic pH at about 7.3, and treatment with vacuolar proton-pump inhibitors reduces the resting pH to 6.7, suggesting proton extrusion from the parasite cells via vacuolar H(+)-A...

HER2 is an attractive immunotherapeutic target for neoplastic disease because this cell surface molecule is overexpressed on a large fraction of malignant tumor cells. To directly assess therapeutic responses to targeted therapy by noninvasive in vivo imaging in small animals, human HER2-expressing ovarian carcinoma cells were genetically modified with a firefly luciferase gene, and light emiss...

Inorganic pyrophosphate promoted the acidification of an intracellular compartment in permeabilized promastigotes of Leishmania donovani, as measured by Acridine Orange uptake. The proton gradient generated by pyrophosphate was collapsed by addition of nigericin or NH4Cl. Pyrophosphate-driven proton translocation was stimulated by potassium ions, and inhibited by NaF, the pyrophosphate analogue...

The vacuolar H(+)-ATPase (V-ATPase) acidifies compartments of the vacuolar system of eukaryotic cells. In renal epithelial cells, it resides on the plasma membrane and is essential for bicarbonate transport and acid-base homeostasis. The factors that regulate the H(+)-ATPase remain largely unknown. The present study examines the effect of glucose on H(+)-ATPase activity in the pig kidney epithe...

To determine the possible contribution of apoptosis in the pathogenesis of acute lung injury (ALI), we investigated Fas antigen (Fas), Fas ligand (FasL), perforin, granzyme A, and granzyme B expressions in a murine model of ALI after intratracheal instillation of Escherichia coli lipopolysaccharide (LPS: 0.3-30 microg) into the left lung. Lung injury, examined by water-to-dry weight ratio and a...

The electric potential of the contractile vacuole (CV) of Paramecium multimicronucleatum was measured in situ using microelectrodes, one placed in the CV and the other (reference electrode) in the cytosol of a living cell. The CV potential in a mechanically compressed cell increased in a stepwise manner to a maximal value (approximately 80 mV) early in the fluid-filling phase. This stepwise cha...

Human immunodeficiency virus type 1 (HIV-1) normally enters cells by direct fusion with the plasma membrane. In this report, HIV-1 particles capable of infecting cells through an endocytic pathway are described. Chimeric viruses composed of the HIV-1 core and the envelope glycoprotein of vesicular stomatitis virus (VSV-G) were constructed and are herein termed HIV-1(VSV) pseudotypes. HIV-1(VSV)...