Quantum Requirement for Photosynthesis in Chlorophyll-Deficient Plants with Unusual Lamellar Structures

Neither an over-all deficiency of chlorophyll, nor an increased enzymatic capacity for maximal rates, nor an unusual lamellar structure was found to change the number of quanta required for the evolution of one molecule of oxygen in healthy aurea mutants of tobacco. The average minimal quantum number remains 10 (efficiency 0.1) as in many algae and typical higher plants. Most of the time the optimal efficiency depends on the availability of some far-red radiation, particularly in the blue region of the spectrum where blue light alone is rather inefficient. These results fit an explanation offered earlier in connection with the hydrogen or acetate photometabolism of algae in far-red light.     

Electron microscopic observations on isolated mitochondrial membranes,prepared by various histological methods

Summary The pictures of isolated mitochondrial membranes, as seen on the electron-microscope, depend very much on the method of specimen preparation. Subunits of linear dimensions of about 25 m, (electron transport particles) are observed in carbon-replicas of the membranes and in specimens treated with trypsin or pepsin (0.02% for 30 mins) and shadowed with platinum. A three-layered structure of the unit membrane is seen in sections of specimens fixed with osmium tetroxide or formalin followed by post-fixation with osmium tetroxide. But fixation with potassium permanganate or with formalin, followed by post-fixation with potassium permanganate reveals an electron-dense globular structural element in the unit membrane. An electron-transparent ultrastructural element of the unit membrane is observed after treatment with trypsin (0.2% for 5 mins) and fixation with osmium tetroxide. Unsectioned specimens treated with 0.02% trypsin for 30 mins show a honeycomb-like structure of the membrane. Thus, part of the results appear to support the concept of a mosaic-like structure of the unit membrane, whereas other results are in agreement with the classical concept of a three-layered structure.The authors wish to express their gratitude to Dr. Sina Rosenthal, Department of Physiological Chemistry, Humboldt University, Berlin, who prepared the isolated membranes, to Mr. E. Fischer, Head Technician of the Department of Electron Microscopy, Greifswald University, who took most of the electron micrographs, to Mr. G. Bartsch, Department of Electron Microscopy, Greifswald University, and especially to Prof. W. Bargmann and to Doz. E. Lindner, Department of Anatomy, Kiel University, for many valuable suggestions.     

Stephanoscyphus (Scyphozoa,Coronatae) und seine direkte Abstammung von den fossilen Conulata

The scyphopolypStephanoscyphus Allman 1874 represents the polyp generation of the scyphomedusan order Coronatae. Though this polyp has been known for more than a hundred years its general morphology, systematics, and evolution have been inadequately described. Participating in the International Indian Ocean Expedition, 1964 to 1965, on board of the German research vessel “Meteor”, the author was able to collect a sufficient supply of livingStephanoscyphus off the coasts of South Arabia and East Africa. For the first time, it was possible to rear these polyps in laboratory cultures. A thorough investigation of morphology, developmental history and behaviour based on longterm observations of the living polyps gave clear indications thatStephanoscyphus directly descended from the fossil group of Conulata, the scyphozoan nature of which has been affirmed byKiderlen (1937) andKnight (1937). The main feature whichStephanoscyphus has in common with the Conulata is the possession of a periderm tube. The characteristics found in a detailed investigation of the periderm tube conform well with those found in the periderm of the Conulata except for the closure of the aperture by triangular flaps which are absent inStephanoscyphus. The soft body contains primitive features as well. Hence it must be concluded finally that the type of organization which the fossil ancestors exhibited has survived inStephanoscyphus and that the Coronatae represent the most basic group of all living Scyphozoa. On the other hand, the results give strong support for the scyphozoan nature of the Conulata, the organization and life history of which have been elucidated by the observations of the living representatives ofStephanoscyphus.     

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Luciferin derivatives in bioluminescence-enhanced enzyme immunoassays

Ultrasensitive bioluminescence immunoassays for the determination of peptides and proteins (illustrated with human urinary kallikrein, bradykinin and the determination of human urinary kallikrein antibody titres) have been developed. The usable ranges of the standard curves are from 5 pg to 5000 pg per litre. The relative intra-assay coefficients of variation of the tests were between 2% and 6%, and the inter-assay coefficients of variation between 4% and 12%.     

Fusion of cultured dog kidney (MDCK) cells: I. Technique,fate of plasma membranes and of cell nuclei

Summary The evaluation of the intracellular signal train and its regulatory function in controlling transepithelial transport with electrophysiological methods often requires intracellular measurements with microelectrodes. However, multiple impalements in epithelial cells are hampered by the small size of the cells. In an attempt to avoid these problems we fused cells of an established cell line, Madin Darby canine kidney cells, originally derived from dog kidney, to giant cells by applying a modified polyethylene glycol method. During trypsin-induced detachment from the ground of the petri dish, individual cells grown in a monolayer incorporate volume and mainly lose basolateral plasma membrane by extrusion. By isovolumetric cell-to-cell fusion, spherical giant cells are formed within 2 hr. During this process a major part of the individual cell plasma membranes is internalized. Over three weeks following cell plasma membrane fusion degradation of single cell nuclei and cell nuclear fusion occurs. We conclude that this experimental approach opens the possibility to investigate ion transport of epithelia in culture by somatic cell genetic techniques.