Contitions for optimal growth of a PSTV-infected potato cell suspension and detection of viroid-complementary longer-than-unit-length RNA in these cells

A suspension culture from potato spindle tuber viroid (PSTV)-infected cells of the wild type potato (Solanum demissum) has been established, which is a suitable model system for studying PSTV replicationin vivo. The conditions for rapid growth of these cells and for permanent extensive viroid biosynthesis within them are described. Biosynthesis of PSTV in the potato cells was demonstrated by³²P-incorporation into nucleic acids and their subsequent electrophoretic analysis on polyacrylamide gels. Under optimum culture conditions the amount of³²P-orthophosphate incorporation into PSTV reached 10% of that incorporated into the 2 M LiCl-soluble cellular RNA. (+)PSTV and its complementary form, i.e. (?)PSTV were identified after their electrophoretic separation on polyacrylamide and agarose gels by molecular hybridization. This analysis revealed the presence of six high molecular weight(?)PSTV species, which are possibly multimers of the unit length(+)PSTV molecule consisting of 359 nucleotides.     

Lymphoid cell subclasses in rejecting renal allograft in the rat

We have quantitated the frequency of lymphoid cell subsets in rejecting renal allografts and in the spleen of the allograft recipient during drug-unmodified rejection in the rat. The number of inflammatory (white) cells in the graft was approximately similar to the number of white cells responding to the allograft in the recipient spleen. The inflammatory population of the graft consisted of lymphoid cells and mononuclear phagocytes, with increasing numbers of macrophages toward the end of rejection. Analysis of allograft cellular dispersates with monoclonal antibodies directed to the lymphoid cell subsets demonstrated that although the majority of allograft-infiltrating lymphocytes were T cells, a sizable B-cell proliferation and immunoglobulin synthesis was associated with the inflammatory response of rejection. Within the T-cell subset, the T suppressor/killer cells predominated in the graft whereas the predominant lymphoid cell subset responding to the allograft in the recipient spleen was the T helper cell.     

Serotonin-like immunoreactivity in the optic lobes of three insect species

The cellular localization of 5-HT in the optic lobes of three insect species was assayed with the use of antibodies raised against 5-HT. In Schistocerca, Periplaneta, and Calliphora all neuropil regions of the optic lobe, the lamina, medulla and lobula, contain 5-HT-immunoreactive varicose fibres in different patterns, like columns and layers. Such fibres also connect the lobula to neuropil in the lateral protocerebrum. In Calliphora also 5-HT-positive fibres of the medulla and lobula plate have projections to the lateral protocerebrum, whereas the origin of the lamina fibres is not certain. In all species the processes displaying 5-HT-like immunoreactivity appear to be derived from a relatively small number of cell bodies, each neuron thus having processes over a large volume of the neuropil of the optic lobe in different layers.     

Dynamics of the cytoskeleton in Amoeba proteus

Fluorescein-labeled muscle actin was microinjected into Amoeba proteus and followed during intracellular redistribution by means of the image-intensification technique. The fully polymerization-competent protein becomes part of the endogenous actomyosin system undergoing dynamic changes over time periods of several hours. Single-frame analysis of long-term sequences enabled the direct demonstration of both the contractile activities and morphological transformations of microfilaments in normally locomoting, immobilized and phagocytozing specimens. In normally locomoting cells the filament layer undergoes continuous changes in spatial distribution depending on the actual pattern of cytoplasmic streaming and cell shape. The highest degree of differentiation is always maintained in the intermediate region between the front and the uroid, thus indicating this segment of the cortex to be the most important site in generating motive force for pseudopodium formation and ameboid movement. In immobilized cells contracted by the application of ruthenium red or relaxed by different anesthetics, the filament layer forms a continuous thick sheath beneath the cell surface or becomes completely disintegrated. In phagocytozing cells the local polymerization of actin at the tip of pseudopodia forming the food-cup and around the nascent phagosome points to a significant participation of the actomyosin system in the process of capturing and constricting prey organisms. Although our results provide clear evidence for the overall importance of motive force generation according to the hydraulic pressure theory, some motile phenomena exist in Amoeba proteus that cannot exclusively be explained by this mechanism.     

Lateral Transport of Ions into the Xylem of Corn Roots: II. Evaluation of a Stelar Pump

When an excised corn (Zea mays) root pretreated with chloride was exposed for 10 minutes to pulse labeling with ³⁰Cl and then transferred to unlabeled chloride, the activity in the xylem exudate reached a maximum about 4 minutes after pulse labeling was discontinued and then declined sharply. The rate at which labeled chloride was transported across the root into the xylem and basipetally therein was on the order of 75 to 250 centimeters per hour. Consequently, symplasmic movement of chloride in corn roots is fast and may not be rate-limiting in transfer from the root surface to the xylem. Experiments on pulse labeling with ²²Na gave similar results. A large fraction of the absorbed ²²Na was not translocated into the exudate but was tightly sequestered in a cell compartment, probably the vacuole.     

Cation permeability induced by spermine and polybrene in rat liver mitochondria

The effect of the polybasic substances Polybrene and spermine on the passive and active transport of monovalent cations in mitochondria was studied. These agents were found to stimulate the low amplitude swelling of mitochondria. Volume oscillations were induced by addition of substrate in the presence of spermine. In conditions where weak oscillations were obtained without these substances, oscillations were stimulated and their frequencies increased in the presence of Polybrene and spermine. Their effects were maximal with 100–300 moles spermine per litre and 3–5 mg Polybrene per litre. These results are discussed in relation to an interaction of the agents studied with membrane negative charges which may be important regulators of ion transport.     

Kinetics of gametogenesis

Cell and Tissue Research - In the rat (Wistar-WU) sexual differentiation of the gonads occurs between days 14 and 15 post conception (p.c.). At this time the oogonia and their parallel population...     

Polyamine als Stimulatoren von Genaktivitäten Eine autoradiographische Studie an Riesenchromosomen von Chironomus thummi

Zusammenfassung Inaktive Riesenchromosomen der Speicheldrüsen ausgewachsener Chironomus thummi-Larven zeigten nach 60 min Inkubation mit 0,05 N Putrescin-, Spermidin-oder Spermin-Lösung erneute Syntheseaktivitäten, die sich im Einbau von radioaktiv markiertem Uridin autoradiographisch zu erkennen geben. Diese Beobachtung wird im Zusammenhang mit der bekannten genaktivierenden Wirkung von Mg⁺⁺ diskutiert. Auf der Basis zahlreicher biochemisch analoger Wirkungen von Polyaminen und Mg⁺⁺ wird ein ursprünglich für die genaktivierende Wirkung von Mg⁺⁺ postuliertes Modell auf Polyamine übertragen.

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Stimulation of gene activities by polyamines an autoradiographic study with giant chromosomes of Chironomus thummi

Summary Inactive salivary gland giant chromosomes of full grown Chironomus thummi larvae showed after 60 min of incubation in 0.05 N putrescine, spermidine or spermine solutions autoradiographically demonstrable incorporation of radioactiv labelled uridine caused by a reactivation of RNA synthesis. This observations is discussed in relation to the known gene activating effect of Mg⁺⁺, and, since polyamines and Mg⁺⁺ have numerous effects in common, it is suggested that polyamines affect gene activity in a way similar to Mg⁺⁺.