H-2 histocompatibility antigens of subcellular membranes of mouse liver

Purified fractions of plasma membrane, Golgi apparatus, rough endoplasmic reticulum vesicles, nuclear envelope, and mitochondria were isolated from mouse liver and the distribution of H-2 histocompatibility antigens determined by indirect radioimmunoassay before and after membrane disruptive treatments. Fractions enriched in plasma membrane (surface membrane) revealed H-2 antigens in highest concentration; disruptive treatments were not necessary to reveal H-2 antigens with surface membranes. In contrast, internal membranes did not possess H-2 antigens which were accessible to antibody. Golgi apparatus fractions or some component of these fractions (e.g. secretory vesicles) possessed the antigens but in a latent form where accessibility was provided by simple rupture of the membrane vesicles. With endoplasmic reticulum, detergent solubilization of the membranes was required before H-2 antigen could be detected. Nuclear envelope preparations contained little or no demonstrable H-2 activity. These results were confirmed by several techniques including immunoprecipitation of labelled solubilized membrane components with anti-H-2 serum and subsequent analysis in SDS-PAGE.     

Basal bodies in the odontoblasts of the limpet,Patella coerulea L. (Gastropoda)

Summary The odontoblasts in the long radular gland of Patella coerulea L. are arranged in a terminal position; therefore newly formed teeth already have an upright position. The long and slender odontoblasts have only one to three lengthy and ramifying apical microvilli. Between these pinnate microvilli a fine filamentous material appears which probably corresponds to chitin microfibrils. Therefore, the pattern of chitin microfibrils seems to depend on the arrangement of odontoblasts' microvilli. For the first time, basal bodies were found in the apical part of odontoblasts which led to the assumption that the radular gland originally might have been a mucous gland, the secretion of which was transported by cilia.     

Figure-ground discrimination by relative movement in the visual system of the fly

The visual system of the fly performs various computations on photoreceptor outputs. The detection and measurement of movement is based on simple nonlinear multiplication-like interactions between adjacent pairs and groups of photoreceptors. The position of a small contrasted object against a uniform background is measured, at least in part, by (formally) 1-input nonlinear flicker detectors. A fly can also detect and discriminate a figure that moves relative to a ground texture. This computation of relative movement relies on a more complex algorithm, one which detects discontinuities in the movement field. The experiments described in this paper indicate that the outputs of neighbouring movement detectors interact in a multiplication-like fashion and then in turn inhibit locally the flicker detectors. The following main characteristic properties (partly a direct consequence of the algorithm's structure) have been established experimentally: a) Coherent motion of figure and ground inhibit the position detectors whereas incoherent motion fails to produce inhibition near the edges of the moving figure (provided the textures of figure and ground are similar). b) The movement detectors underlying this particular computation are direction-insensitive at input frequencies (at the photoreceptor level) above 2.3 Hz. They become increasingly direction-sensitive for lower input frequencies. c) At higher input frequencies the fly cannot discriminate an object against a texture oscillating at the same frequency and amplitude at 0° and 180° phase, whereas 90° or 270° phase shift between figure and ground oscillations yields maximum discrimination. d) Under conditions of coherent movement, strong spatial incoherence is detected by the same mechanism. The algorithm underlying the relative movement computation is further discussed as an example of a coherence measuring process, operating on the outputs of an array of movement detectors. Possible neural correlates are also mentioned.     

Ferritin as an exogenous yolk protein in snails

Summary A main yolk component in the oocytes of the pulmonate snailPlanorbarius corneus L. has been isolated and identified as the iron storage protein ferritin by its ultrastructure, iron content, immuunological properties and behaviour in disc electrophoresis. As judged from acrylamide electrophoresis data and ultrastructural observations, yolk ferritin is an exogenous protein which is synthesised in the hepatopancreas and taken up by the oocytes by endocytosis.     

Fusion of two F-prime factors inEscherichia coli studied by electron microscope heteroduplex analysis

Summary A fused F prime factor was obtained from a mating of arecA donor carrying an F' factor containing the genesmetBJF, ppc andargECBH (KLF5) with arecA recipient carrying an F' factor containingatt80, trp andlac (F155). Lysogenization of this fused F-prime factor with cI⁸⁵⁷ h80 phage followed by thermoinduction produced the transducing phages 80dmetBJF and 80dppcargECBH. This kind of fusion provides a general procedure for the construction of transducing phages carrying genes from different regions of theE. coli genome. To understand the mechanism of this fusion, the parental F prime factors (F155 and KLF5) were analyzed by the electron microscope heteroduplex technique.F155 has a length of 176±3 kilobases including two substitutions. The F sequence 0 F-2.8 F has been substituted by 53 kb of chromosomal DNA including thelac operon and the F sequences 8.5 F-16.3 F has been substituted by 27 kb of a chromosomal sequence includingatt80 and thetrp operon.KLF5 contains 221±4 kilobases of DNA (molecular weight, 148 megadaltons). It contains complete F and the segment of theE. coli chromosome frompolA torif. The F sequence 2.8 F-8.5 F known to be involved in F specific recombination inrecA ⁺ andRecA backgrounds occurs twice on KLF5, once at each of the junctions of F DNA with chromosomal DNA. The population of closed circular plasmid molecules extracted from KLF5-containing strains is heterogeneous. It is proposed that this heterogeneity is due to intramolecular recombination events occurring in KLF5 between the duplicated 2.8 F-8.5 F sequences. Such recombination can account for the genetic instability of KLF5 observed in bothrecA ⁺ andrecA hosts. The F sequence 2.8 F-8.5 F (also called ) is one of the characterized integration sequences on F.A model for the fusion of the parental F prime factors is proposed in which recombination between sequences bringsatt80 close to themetBJF genes. This is followed by a deletion of an F'lac factor. The resulting fused F' factor still carries two sequences and is therefore expected to be unstable. The closed circular molecules isolated from the fused F' containing strains show two different sizes of molecules. Genetic and physical analyses of these molecules are in agreement with the predicted instability of the fused F' factor and the existance of the sequence in the 80dmet phages isolated from fused F' and previously analyzed by the electron microscope heteroduplex technique.     

In vitro synthesis and repression of argininosuccinase in Escherichia coli K12; partial purification of the arginine repressor

Summary 80dargECBH DNA has been used to direct cell-free synthesis of argininosuccinase, the argH gene product in Escherichia coli K12. In vitro enzyme synthesis is sensitive to repression by partially purified preparations from an argR ⁺ strain but not by corresponding preparations from an argR ^- strain. Using DNA-cellulose chromatography, approximately seventyfold purification of repressor has been obtained. The partially purified preparation represses argininosuccinase synthesis but has no effect on -galactosidase synthesis.     

Entwicklung und Bau der Doppelspermien bei den DytiscidenAcilius sulcatus L.,Dytiscus marginalis L. undHydaticus transversalis Pont. (Coleoptera)

Zusammenfassung BeiAcilius sulcatus undDytiscus marginalis wurde die Spermiogenese bis zu den reifen Doppelspermien, beiHydaticus transversalis wurden nur die reifen Doppelspermien untersucht. Die Konjugation der Spermien dieser Arten erfolgt als letzter Schritt erst im distalen Teil des Hodenausführungsganges. Voraussetzungen für ihr Zustandekommen sind sowohl lokale Differenzierungen der Spermienmembran, alsauch spezifische polysaccharidhaltige Beläge, von denen nach dem Aussehen sowie nach Zeitpunkt und Ort ihres Auftretens vier unterschieden werden können, die teils schon im Zystenlumen, teils erst nach Eindringen des Spermienvorderendes in tiefe Fächer der Zystenwandzellen gebildet werden. Die mit allen Belägen versehenen Einzelspermien treten zusammen mit abgeschnürten Resten der Zystenwandzellen in den Ausführungsgang ein, dessen Epithel die Plasmareste der Zystenwandzellen phagozytiert. Die Beläge der Spermien sind nach der Konjugation verändert. Damit muß als letzte Bedingung für das Zustandekommen des Aneinanderhaftens noch eine Reaktion im Ausführungsgang stattfinden. Weiterhin wurde die Entwicklung des als microtubular border beschriebenen Strukturelements im Schwanz verfolgt und als centriole adjunct identifiziert, welches sich aus Kernmaterial herleitet und zu einem Geißelbegleitkörper modifiziert hat. Schließlich wird auf anscheinend regelmäßige und in zeitlich abgestimmter Folge auftretende Beziehungen des Endomembransystems zu den sich differenzierenden Strukturen der Spermatide hingewiesen.

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Development and structure of the conjugate sperm of the dytiscidaeAcilius sulcatus L.,Dytiscus marginalis L. andHydaticus transversalis pont. (Coleoptera)

Summary Spermiogenesis and structure of the double sperm have been investigated inAcilius sulcatus andDytiscus marginalis whereas only mature double sperm have been studied inHydaticus transversalis. The conjugation of the sperm in these species is accomplished as a last step in the distal part of the vas deferens. Preconditions for the pairing are local differentiations of the sperm membrane in combination with specific layers of polysaccharids. According to their aspect as well as the chronological order and place of their appearance four such layers can be discerned. These are formed in part still in the lumen of the cyst, in part not earlier than after the anterior ends of the sperm have deeply entered into recesses of the surrounding cyst wall cells. Single sperm supplied with all layers and cytoplasmic remnants pinched off from the cyst wall cells enter the vas deferens where the cytoplasmic remainders are phagocytised by its epithelial cells. The layers of the sperm are transformed after conjugation. Thus as a last precondition for the occurrance of pairing a reaction in the vas deferens must take place. Furthermore, the development of the structural element of the tail described as microtubular border has been traced and identified as a centriole adjunct derived from nuclear material and modified to a body accompanying the flagellum. Finally, it is pointed out that apparently regular relationships in temporally correlated sequence exist between the endomembranous system and differentiating structures of the spermatid.

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Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.

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För die rasterelektronenmikroskopischen Aufnahmen der Abb. 9 danke ich Frau L. Schulz, Homburg, verbindlichst. Die Teilbilder 16g u. h konnten mit einem Siemens Elmiskop 102 aufgenommen werden. För die Anfertigung dieser Aufnahmen bin ich Frau Dr. C. Weichan, Berlin, zu Dank verpflichtet.     

A special class of nonlinear interactions in the visual system of the fly

Flies can detect a small object in front of a randomly contrasted background if the object undergoes small motions. The effect was investigated in fixed flying flies under open-loop conditions. The results suggest that nonlinear inhibitory interactions underly this elementary case of figure-ground discrimination.     

Über zwei diploide,in Südwest-Anatolien endemische Arten aus dem Komplex derVeronica cymbalaria (Scrophulariaceae)

Veronica lycica Lehm. is a distinct, diploid member of theVeronica cymbalaria group, endemic in Lycia (S.W. Anatolia). Closely related is the newV. stamatiadae M. Fischer etW. Greuter which is also diploid and seems to be restricted to the small Greek island Ro close to the South coast of Lycia. The chromosome numbers for both species are reported for the first time (2n = 18).

Untersuchungen über den PolyploidkomplexVeronica cymbalaria agg., II. — Der erste Beitrag dieser Serie:Fischer (1975).