Effects of isoproterenol on the dense core and perigranular membrane of atrial specific granules

Summary Following subcutaneous injections of isoproterenol hydrochloride (ISO), atrial cells present a large number of partly degranulated or completely clear specific granules enclosed by an intact membrane. Such profiles were never encountered in normal controls and might suggest ISO-induced release of a secretory product. Permeability of perigranular membrane was tested using the extracellular macromolecular tracer horseradish peroxidase (HRP). Reaction product was entirely absent within granules of atrial cells in which the sarcolemma was made permeable to HRP molecules by the ISO injections. This seemed to be the case even in heavily labelled cells in which the peroxidase had penetrated the mitochondrial membranes. In atrial cells impermeable to the tracer, the specific granules closely apposed to the sarcolemma were always HRP-negative. The release mechanism of a possible secretory substance from the specific granules is discussed.     

Synthesis of sucrose epoxides,partial de-esterification of 1′,2:4,6-di-O-isopropylidenesucrose tetra-acetate,and selective tosylation of 3,6′-di-O-acetyl-1′,2:4,6-di-O-isopropylidenesucrose

Selective de-esterification of 1′,2:4,6-di-O-isopropylidenesucrose tetra-acetate² (1) with methanolic ammonia at ?10° gave an inseparable mixture (2+3) of the 3,4′,6′- and 3,3′,6′-triacetates and also the 4,6′-diacetate 4. When the reaction was performed at 5°, it gave 4, the 4-acetate 8, and the parent diacetal 9. These derivatives allow selective reaction at hydroxyl groups in sucrose, in particular at HO-3′ and, HO-4′, not hitherto possible. Mesylation of 4 gave the 3′,4′-dimesylate 7, which, on treatment with aqueous acetic acid followed by acetylation, afforded 3′,4′-di-O-mesylsucrose hexa-acetate (11). Treatment of 11 with sodium methoxide in methanol at 70° for 1 min gave the ribo-3′,4′-epoxide 12 as the minor, and the lyxo-3′,4′-epoxide 13 as the major, product. Selective tosylation of 4 gave the 3',4'-ditosylate 14 (3.7%), 4′-tosylate 15 (3.1%), and 3'-tosylate 16 (31%), indicating the order of reactivity HO-3′>HO-4′ in 4. De acetalation of 15 and 16 followed by acetylation gave the hepta-acetates of 4′- and 3′-O-tosylsucrose, respectively, which were converted into the respective epoxides, 13 and 12, by methanolic sodium methoxide.     

Structural proteins in the growth cone of cultured spinal cord neurons

The distribution of several structural proteins in the extending neurites and growth cones of cultured embryonic mouse spinal cord neurons was studied by indirect immunofluorescence, using affinity chromatography-purified antibodies. Fibroblastic cells in the same cultures served as internal standards for the evaluation of staining intensities. Anti-tubulin, anti-actin, and anti-clathrin stained neurons and their processes intensely, while staining with anti-α-actinin was only moderate compared with fibroblasts. Microtubules were resolved by anti-tubulin in the ‘palm’ of the growth cone but not in the neurite. Anti-actin stained even the finest lamellae and filopodia of the growth cone, and the neurite. Anti-α-actinin revealed an irregularly speckled pattern of cross-reactive material in the neurite and in the palm of the growth cone and was absent from the filopodia. Anti-clathrin stained the neurite intensely and homogeneously, and to a lesser extent the palm of the growth cone. The staining with antibodies against tubulin and clathrin differed grossly between neurons and fibroblastic cells. Within the neuron there were only gradual differences in staining intensities. The growth cone was not qualitatively different from the rest of the neurite, except for the filopodia which lacked tubulin and α-actinin, similar to the microvilli of epithelial cells.     

Cytokinesis in the green alga Eremosphaera viridis: Plasmalemma formation from “open membranes”

Summary Cytokinesis in the unicellular chlorococcalean alga Eremosphaera viridis de Bary has been investigated by electron microscopy of thin sections. The new plasmalemmata of the daughter cells in this organism form centrifugally within a phycoplast. Unlike other cell division systems each new plasmalemma is formed, not by the fusion of vesicles, but rather by the fusion of open membranes which are characteristically heavily stained. Measurements of these open membranes reveal that they are 11 nm thick with a central 4,5 nm unstained portion. The possible origin of these open membranes as burst-open vesicles has been suggested from the presence of intensely straining vesicles in the vicinity of the cell equator. Calculations of vesicle and open membrane surface areas support this contention.     

ESR and optical absorption studies on the copper (II) interaction with aromatic amino acids

Electron spin resonance and optical absorption studies have been done in order to investigate the interaction between Cu²⁺ and aromatic amino acids in aqueous solution at 77 K and at room temperature as well. Depending on the concentration each aromatic amino acid can form two different kinds of complexes with Cu²⁺ which can be characterized by its ESR pattern. Additional information was obtained from optical d-d and CT transitions.     

Interactive effects of season and temperature on enzyme activities,tissue and whole animal respiration in roach,Rutilus rutilus

Synopsis This paper reviews investigations on the ecophysiology of a population of roach, Rutilus rutilus, from a subalpine oligotrophic lake in the Austrian Tirol. Metabolic responses to season and temperature were studied in whole animals, tissues and selected enzymes. The exponent of the relationship between body mass and three levels of the metabolic rate of acclimated fish was 0.82 ± 0.02, 0.60 ± 0.15, and 0.75 ± 0.01 at 4, 12, and 20° C respectively. Various combinations of long-term acclimation to constant or seasonally fluctuating temperatures and long-term (up to 14 days) monitoring of O₂ at the acclimation temperature led to the conclusion that the aerobic power of fish swimming in the routine mode does not show any sign of being temperature compensated. On the other hand, there are several indications that the energy expenditure of spontaneously swimming fish is adjusted to the seasonal pattern of environmental change and that these responses of metabolism and behaviour are controlled by both endogenous and exogenous factors. The rate of oxygen consumption of gill and muscle tissue brei from fish caught during a seasonal cycle and measured at 15° C appears to follow closely the reproductive and gonadal cycle of the living fish. The same holds for the activities of phosphofructokinase, acetoacetyl-CoA thiolase, and cytochrome oxidase. On the other hand, the Na⁺, K⁺-ATPase of the kidney shows near perfect temperature compensation when fish acclimated to 5 and 25° C are compared, whereas an equally pronounced case of inverse temperature acclimation has been reported for the activity of digestive enzymes in the gut. Summarizing these data it is pointed out that the temperature relationship of a poikilothermic organism is the sum of often very diverse temperature relationships of specific metabolic and behavioural functions. In the case of the roach, strong effects of acclimation temperature on the molecular level, sometimes in the opposite direction, combine with seasonal effects on enzyme activities and tissue respiration. However, on the whole animal level the fish behave as strictly non-compensating poikilotherms, the reproductive cycle being the only detectable influence capable of modulating the basic temperature relationship of energy expenditure.     

The puff-specific Drosophila protein Bj6, encoded by the gene no-on transient A,shows homology to RNA-binding proteins

The DNA coding for the puff-specific protein Bj6 has been isolated by expression cloning. The gene is localized in 14C1,2 on the X chromosome and is expressed ubiquitously during embryonic development with prominent expression during the first 12 h of embryogenesis. cDNA and genomic clones have been sequenced and show a single open-reading frame of 2.1 kb length, coding for a M_r=77000 basic protein. In the aminoterminal half of the protein we detect stretches of repeated amino acids, centrally a region with homology to RNA-binding proteins containing the RNP 1 and RNP 2 consensus motif of RNA binding proteins, and the carboxyterminal part is rich in charged amino acids. The Bj6 protein is a product of the gene no-on transient A, a gene required for normal vision and courtship behaviour in Drosophila.W. Hennig     

Dichtebedingter Zusammenhang zwischen Gesangstyp und ?kotyp bei der Grauammer(Emberiza calandra)?

Zusammenfassung Zwei Gesangstypen (N, S, s. Abb. 1 a, b) dürften dichteabhängig sein. Durch Tonbandreizung (Dichtesimulation?) läßt sich ein einseitiger Übergang von einem (N) zum anderen Typ (S) — beim Individuum nur in einem Halbschritt (s. Abb. 3) — provozieren. Ein dritter Gesangstyp (K, Abb. 1 c) war zu selten im Material vorhanden, um weitergehende Aussagen zu ermöglichen. Außerdem sind die Gesangstypen geographisch unterschiedlich verbreitet: N und NS (intermediär, s. Abb. 2 a) in feuchtem Steuwiesenhabitat in Mitteleuropa in kleinen, eher dispers siedelnden Population; S in trockenen teilweise kultivierten Steppenhabitaten S-Europas mit augenscheinlich sehr hoher Dichte. In Österreich und in der Schweiz gibt es auch N/S-Sänger (beide charakteristischen Elemente in einer Strophe); diese könnten von beiden Formen lernbeeinflußt sein. Diese Anhaltspunkte werden in ein Modell (Abb. 4) eingebaut.

---

Density-dependent coherence of song-type and ecotype in the Corn BuntingEmberiza calandra?

Summary There are two major song-types (N, S, fig. 1 a, b) in the Corn Bunting which seem to be density-dependent. An unidirectional change to (wards characters of) type S was observed when a density-situation was simulated by playback of song (any type); fig. 3. Data of a third type (K, fig. 1 c) are too scarce to provide such significance. Without playback-experiments these types have an unequal geographic distribution (table): N and NS (intermediary type, fig. 2 a) occurring in moisty meadowland in Central Europe (small colonies of low density) S beeing most typical for dry, partly cultivated steppe-habitats in southern Europe (Evros-Delta, Greece; Camargue, southern France) where density is extremely high. In the eastern Austrian Seewinkel (lake Neusiedel) there are N/S-singers (mixed elements, see fig. 2 b) which might be cultural hybrids (Baptista 1975). These findings suggest a model which is expressed in this paper's title and fig. 4.

     

Methanococcus thermolithotrophicus,a novel thermophilic lithotrophic methanogen

An autotrophic thermophilic motile coccoid methanogen was isolated from geothermally heated sea sediments close to Naples, Italy. Growth occurs on H₂/CO₂ and on formate between 30 and 70°C with an optimum at 65°C. The optimal doubling time is only 55 min. The NaCl-concentration ranges from 1.3% to 8.3% with an optimum around 4%. By its G+C-content of 31.3 mol%, its subunit envelope, and by DNA-RNA hybridization the new isolate is clearly defined to be a member of the genusMethanococcus. We name itMethanococcus thermolithotrophicus.Abbreviations G+C Guanine + Cytosine - SDS Sodium dodecylsulfate (Sodium lauryl sulfate)