Angiosperm leaf fossils (16.7-25 x 10(6) years by potassium/argon dating) referable to Zelkova were isolated from pyroclastic deposits in the Succor Creek Formation, Oregon. These fossils reveal a three-dimensional structure in mesophyll cell layers and vascular bundles, while transmission electron microscopy of fixed tissues reveals well-preserved chloroplasts with grana stacks and starch, as ...

All animals were live-trapped in south-east Tasmania. Details of number and sex ar~ shown. in the table. Skins and skulls of all specImens, WIth trapping data, are lodged in the Ta~ma~an Museum, Hobart, and their museum regIstratIOn numbers are also shown in the table. The animals were killed with trichloroethylene and tissues for examination removed immediately after death. The most successful...

To assess the role of clathrin in the bulk endocytic flow of rat foetal fibroblasts, the rate of internalization of fluid-phase and membrane-lipid tracers were compared, under control conditions and after inhibition of endocytic clathrin-coated pit formation. After intracellular potassium depletion or upon cell transfer into 0.35 M NaCl, the rate of internalization of receptor-bound transferrin...

The effect of T-2 toxin on the nerve cell membrane was investigated using 25 unidentified neurons of the visceral ganglion of the mollusc Lymnaea stagnalis .The method was performed by intracellular dialysis and perfusion of neurons under fixation of tension on these membranes.T-2 toxin within concentrations occurred between 10 -6 to 10 -3 mol / L blocked delayed potassium ion current I s k amp...

The effect of the potassium channel blocker 4-aminopyridine (4-AP) on spontaneous upbeat nystagmus (UBN) was investigated with the search coil technique during fixation in different gaze positions and smooth pursuit in a patient before and after ingestion of 10 mg 4-AP. UBN was reduced from 8.6 deg/s to 2.0 deg/s by 4-AP causing subjective relief from distressing oscillopsia, and impaired upwar...

Utilization of heavy metals in electron microscopy to obtain image contrast of a degree greater than that resulting from fixation with osmium tetroxide or potassium permanganate is now an accepted practice. Staining is virtually essential when an epoxy resin is used as embedding medium, but only a small number of compounds have been suggested and few of these are in routine use. Lead hydroxide ...

Non-specific hemolysis has often been observed during complement-fixation (CF) tests for equine herpesvirus type-1 (EHV-1), even when the sera have virus-specific CF antibodies. This phenomenon has also been reported in CF tests for various infectious diseases of swine. We found that the sera from 22 of 85 field horses (25.9%) showed non-specific hemolysis during conventional CF testing for EHV...

The cytoplasm of the rat isolated fat cell contains a highly organized, interconnected system of smooth endoplasmic reticulum having close association with the central lipid mass, mitochondria and cytoplasmic lipid droplets. Elements of smooth endoplasmic reticulum approach, but do not fuse with, the plasma membrane. When fat cells were treated with potassium pyroantimonate during fixation for ...

We studied hearts in which hypertrophy was caused by both pressure and volume overload. Pressure hypertrophy was induced by an aortic constriction; volume hypertrophy was induced by an iron-copper deficiency (anemia). The ventricular weight was increased by 34% in the pressure-hypertrophied hearts at the end of 6 weeks. The ventricular weight was increased by 54% in the volume-hypertrophied hea...

Fluorescence-and electron-microscopic studies were performed on nerve terminals close to intracerebral blood vessels in the rat. For the electron microscope subdural perfusion fixation with potassium permanganate was used. In the rat cerebral cortex deprived of the bilateral superior cervical ganglion some aminergic terminal boutons containing large and small core vesicles were observed contigu...