Intracellular and Extracellular Uptake of Cadmium by the Moss Rhytidiadelphus squarrosus

Intra- and extracellular Cd uptake were investigated in themoss Rhytidiadelphus squarrosus. Intracellular Cd uptake displayedMichaelis–Menten kinetics and showed that the moss hada high uptake rate and high affinity for Cd. Extracellular Cdbinding capacity was also high. The anion used had little effecton Cd uptake to either location but both intra- and extracellularCd uptake were reduced by equimolar concentrations of Ca, Mgor Zn, although inhibition was not wholly competitive. IntracellularCd uptake was not significantly affected by the supply of energygenerating reserves but, like extracellular Cd uptake, showedaltered characteristics following growth under controlled laboratoryconditions. The results are compared with data on Cd uptakeby the lichen genus Peltigera. Rhytidiadelphus squarrosus, moss, cadmium, intra- and extracellular uptake characteristics, kinetics     

Different secretory pathways of renin from mouse cells transfected with the human renin gene

Mammalian cells in culture, transfected with human renin gene, can provide a useful tool for studying renin biosynthesis and secretion. We transfected fibroblast cells (mouse L929 and Chinese hamster ovary cells) and pituitary tumor cells (mouse AtT-20) with the human renin gene and a selectable plasmid (pSV2Neo). Transfected fibroblasts synthesize prorenin only. Prorenin is secreted by fibroblasts constitutively and the secretion is not influenced by 8-bromo-cAMP. On the other hand, transfected AtT-20 cells synthesized both prorenin and mature active renin. Transfected AtT-20 cells release prorenin by constitutive secretion but mature renin is secreted by a regulated mechanism since the secretion of the former is not influenced by 8-bromo-cAMP but the release of the latter is significantly stimulated. Our studies demonstrate that human renin may be secreted by at least two cellular pathways: prorenin by a constitutive pathway and mature renin by a regulated pathway. These transfected cells may provide useful models for studies of human renin synthesis, processing, and secretion.     

Measurement of cerebral blood flow by transcranial Doppler ultrasonography in children presenting with autistic behavior. Preliminary results

Transcranial Doppler ultrasonographic recordings of the middle cerebral arteries were performed on eight children with autistic behavior compared to eight controls. Blood flow measurements were assessed at rest and during auditory and visual stimulations. The main result was obtained during the auditory stimulations and concerned the left artery blood flow which is lower in autistics than in controls in these conditions (p less than .02). This result confirms the possibility of a left hemisphere dysfunctioning in autistics and may be related to clinical features as language disabilities and paradoxical reactivity to auditory stimuli.     

Critical manifolds,travelling waves,and an example from population genetics

A generalized Morse index theory is used to study travelling waves in a natural selection-migration model for a diploid organism when the selective strength is weak.