Photoreceptors in the pineal of lower vertebrates: Functional aspects

Summary The pineal of lower vertebrates characteristically contains true and modified photoreceptors with functional und structural homologies to retinal photoreceptors. Afferent nerves convey photic information from the pineal to sensory areas of the brain stem. Light also influences synthetic activity within the organ, controlling the rhythm in melatonin production which is generated endogenously. The molecular mechanisms underlying this rhythmic event are described and the hypothesis advanced that the pineal transduces several forms of environmental stimulus involved in the regulation of rhythmic function.     

Influence of classical immunosuppressants on spleen colony formation in mice

Zusammenfassung Nachweis eines Hemmeffektes immunosupressiver Mittel (Cortison, Cyclophosphamide und Immuran) bei Mäusen nach UV-Bestrahlung auf die hämopoetische Regeneration (Milzkolonien und Knochenmarkzellen).     

Murine type C endogenous virus expression in murine 129 teratocarcinoma cell line]

Murine type C viral information is detectable in the cellular genome of both differentiated and undifferentiated cell lines derived from 129 Mouse teratocarcinoma. Cytoplasmic RNA expression which is negligible in differentiated cells, is significantly higher in multipotential undifferentiated cells. Furthermore it was observed that in vitro differentiation of multipotent cells leads to a decrease of this expression.     

Anti-myosin stains chromaffin cells

Summary The presence in fixed chromaffin cells of antigenic sites for a myosin antibody was demonstrated using immunofluorescence techniques. Tests on viable cells showed that at least some of the antigenic sites seem to be localized on or close to the cell surface and explained the cell agglutination that occurred with the addition of the myosin antibody to cells isolated by a method described in this paper.Acknowledgments. This work was supported by grants from the Medical Research Council of Canada. We thank Dr B. G. Livett for advice in the preparation of isolated cells, Drs J. Lowenthal and B. Collier for comments and Mrs J. Ritchie for technical assistance.     

Distribution of bilateral dorsal root potentials evoked by volleys in afferents entering lumbar and sacral segments of the spinal cord

Summary Ipsilateral dorsal root potentials evoked by volleys entering lumbar and sacral segments of the cord are largest at the level of entry of afferent volleys. Contralateral potentials resulting from stimulation of any of these nerves attain maximum amplitude in lower sacral and upper caudal segments.     

Role of a free-living amoeba from water, Acanthamoaba castellani, in the transport of naked or enveloped animal viruses

The trophozo?ts of Acanthamoeba castellanii are unable to adsorb poliovirus or vesicular stomatitis Virus. After encystment in medium containing respectively 5.4 x 10(8) and 3 x 10(9) P.F.U./ml cysts did not contain Viruses. These data do not agree with a current hypothesis by which water's free Amoeba could carry animal Viruses.     

Synthesis of ovulation-inhibiting compounds; structure-activity relationship.

We describe the synthesis of some new derivatives of benzo(4, 5)cyclohepta(1, 2-b)thiophene which inhibit ovulation and the secretion of luteinizing hormone (LH) in the rat. We also describe the relationship between the structure and activity of these compounds.