Abstract. The integrin VLA-3 is a cell surface receptor, which binds to fibronectin, laminin, collagen type

No abstract

Stationary-phase cells of Paramecium tetraurelia have most of their many secretory vesicles ("trichocysts") attached to the cell surface. Log-phase cells contain numerous unoccuFiied potential docking sites for trichocysts and many free trichocysts in the cytoplasm. To study the possible involvement of cytoskeletal elements, notably of microtubules, in the process of positioning of trichocysts at the cell surface, we took advantage of these stages . Cells were stained with tannic acid and subsequently analyzed by electron microscopy . Semithin sections allowed the determination of structural connections over a range of up to 10

an IgG directed against Paramecium actin, a DNAase I-gold complex, and the induction of F-actin polymerization. The trichocysts were analyzed in situ as well as after isolation by density-gradient centrifugation. Additionally, in response to current reports in the literature, we reanalyzed trichocyst contents for any possible presence of calmo

Extremely thin sections of unstained materials (beef liver catalase, double‐stranded calf thymus DNA, horse spleen ferritin and mammalian skeletal muscle), embedded in the water‐soluble melamine resin Nanoplast FB101, were studied by dark‐field electron microscopy and electron spectroscopic imaging. While ferritin molecules so recorded show 04 and 09 nm lattice fringes within the crystalline iron core, double‐stranded DNA shows a helical repeat with a spacing of 34 nm. The gain in resolution of structural detail reported here is probably due mainly to the reduced section thickness as compared to traditional thin‐sectioning techniques. As we reported earlier (Frösch & Westphal, 1984), melamine resins can be sectioned extremely thinly (<10 nm) and observed without a supporting film, making them especially suitable for dark‐field electron microscopy.