Co-existence of immunoreactivity to anti-dopamine,anti-serotonin and anti-vasotocin in the cerebral giant neuron of the pond snail Lymnaea stagnalis

Summary Consecutive sections of certain neurons in the central ganglia of the pond snail Lymnaea stagnalis appear to be immunoreactive to anti-dopamine and anti-serotonin. The Cerebral Giant Neurons stain in addition with antivasotocin. The observations indicate the presence of two biogenic amines within the same neuron and in addition their co-existence with a biologically active peptide.     

Smooth muscle and myofibroblast-like cells in the perimedullary stromal basket of kidneys from ringed seals (Phoca hispida)

Summary The medullary pyramid of renculi in kidneys of ringed seals (Phoca hispida) is enclosed by a basket composed of ribbons of stromal tissue continuous with the wall of the calyx. Branched smooth muscle cells with well-developed Golgi complexes and rough endoplasmic reticulum and only an incomplete external lamina are the principal cells in sites near the origin of the ribbons from the calycal wall. Deeper in the corticomedullary junctional region, smooth muscle is progressively replaced with stellate or spindle-shaped cells exhibiting structural characteristics intermediate between those of fibroblasts and smooth muscle fibers. These myofibroblast-like cells contain arrays of parallel microfilaments 6–8 nm thick with associated focal densities and subplasmalemmal dense plaques, caveolae, elongate, often deeply wrinkled nuclei, and well-developed Golgi complexes and rough endoplasmic reticulum. Material resembling external lamina is associated with parts of the surfaces of most myofibroblast-like cells and intermediate junctions are present. Fibroblasts lacking arrays of parallel microfilaments are a minority at any level in the stromal ribbons. Interstitial cells in the vicinity of the corticomedullary junction show similar myofibroblast-like characteristics. The smooth muscle and myofibroblast-like cells presumably assist expression of urine from the papilla and calyx, and possibly participate as pacemakers for the urinary tract.     

Induction of porphobilinogen oxygenase and porphobilinogen deaminase in rat blood under conditions of erythropoietic stress

Porphobilinogen is the substrate of two enzymes: porphobilinogen deaminase and porphobilinogen-oxygenase. The first one transforms it into the metabolic precursors of heme and the second diverts it from this metabolic pathway by oxidizing porphobilinogen to 5-oxopyrrolinones. Rat blood is devoid of porphobilinogen-oxygenase under normal conditions while it carries porphobilinogen-deaminase activity. When the rats were submitted to hypoxia (p_O2 = 0.42 atm) for 18 days, the activity of porphobilinogen-oxygenase appeared at the tenth day of hypoxia and reached the maximum at the 14–16th day. It decreased to a half after 2 days (half-life of the enzyme) and disappeared after 4 days of return to normal oxygen pressure. Porphobilinogen-deaminase activity increased after the first day of hypoxia, reached a maximum at the 14–16th day and did not decrease to normal values until the 15th day after return to normal oxygen pressure. The activities of both prophobilinogen-oxygenase and porphobilinogen-deaminase were induced by administration of erythropoietin. When rats were made anaemic with phenylhydrazine, porphobilinogen-oxygenase activity also appeared in the blood cells. Although the reticulocyte concentration was higher when compared to that obtained under hypoxia, the activities of the oxygenase obtained under both conditions were comparable. Porphobilinogen-deaminase activity was always closely related to the reticulocyte content. The appearance of porphobilinogen-oxygenase under the described erythropoietic conditions was due to a de novo induction of the enzyme, as shown by its inhibition with actinomycin D and cycloheximide. Porphobilinogen-oxygenase as well as porphobilinogen-deaminase were present in the rat bone marrow under normal conditions. Their activities increased in phenylhydrazine treated rats. The properties and kinetics of porphobilinogen-oxygenase from the rat blood and bone marrow were determined and found to differ in several aspects.     

Effect of ethanol on the specific transport system for L-lysine inSaccharomyces cerevisiae

Preincubation of resting cells of Saccharomyces cerevisiae double mutant can1 gap1 (with a single transport system for L-lysine) with metabolic substrates stimulated subsequent uptake of lysine. While in the wild type the stimulation is connected primarily with carrier protein synthesis (delayed, cycloheximide-inhibitable effect) in the mutant an immediate tapping of an energy source (antimycin-inhibited) is practically solely involved.     

Ultrastructural differences between the myelin sheaths of peripheral nerve fibres and CNS white matter

Summary Electron microscopic studies of peripheral nerves and spinal cord white matter of adult mice, as prepared by the freeze-etching method, show distinct differences in the periodicity of the myelin lamellae as well as of the ultrastructural lamellar pattern. A periodicity of 185 Å is to be determined for peripheral myelin whereas it is 160 Å in the myelin of central origin.In contrast to the appearance in the peripheral myelin the lamellar structure in the central myelin sheath is less pronounced and tends towards a fundamental repeating unit of 80 Å.This work was supported by the Swiss National Foundation (Nr. 4065).