Slime mould Physarum polycephalum is a single cell visible by the unaided eye. Let the slime mould span two electrodes with a single protoplasmic tube: if the tube is heated to approximately ≈40 °C, the electrical resistance of the protoplasmic tube increases from ≈3 MΩ to ≈10,000 MΩ. The organism's resistance is not proportional nor correlated to the temperature of its environment. Slime mould...

The effect of isoniazid on the protoplasmic viscosity in the H37Ra strain of Mycobacterium tuberculosis was determined by using electron spin resonance spectroscopy and a small spin label tempone (2,2,6,6-tetramethylpiperidone-N-oxyl radical). Isoniazid (0.5 mug/ml) caused the internal cellular viscosity to increase gradually over the first 15 h of exposure from a rotational correlation time va...

One of the most distinguishing features of the adult human brain is the complexity and diversity of its cortical astrocytes. Human protoplasmic astrocytes manifest a threefold larger diameter and have tenfold more primary processes than those of rodents. In all mammals, protoplasmic astrocytes are organized into spatially non-overlapping domains that encompass both neurons and vasculature. Yet ...

Membrane halves of boar sperm flagella were produced by freeze-fracture and labeled in situ with concanavalin A and wheat germ agglutinin; the lectins were visualized with protein-gold complexes. Concanavalin A and wheat germ agglutinin binding sites partition with both protoplasmic and exoplasmic halves of the membrane. A high density of lectin marking was found on protoplasmic membrane halves...

The plasmodium of the slime mold, Physarum polycephalura, has been extensively used as a model organism in studies of protoplasmic streaming (1). Recently both streaming in the living plasmodium and the viscosity of suitably prepared plasmodial extracts have been shown to respond specifically to additions of ATP. The plasmodla exhibit increased streaming (2), whereas the extracts become less vi...

A new procedure is described for silver impregnation of thin sections for electron microscopy. Sections of various tissues, fixed in OsO(4) and embedded in methacrylate, were treated with an ammoniacal silver solution, directly or after oxidation with periodic acid or hydrogen peroxide. After OsO(4) fixation all cellular membranous systems exhibit a primary argentaffinity probably due to the re...

Sudden local chilling causes action currents to be set up in Nitella and in Chara, an effect which does not follow gradual local chilling. This may be due to a partial solidification of the non-aqueous protoplasmic surfaces which makes them susceptible to rupture by the protoplasmic streaming. This movement continues usually for several minutes after the chilling, whereas if stimulation occurs ...