Influence of acetylcholine and light on the bioelectric potential of bean (Phaseolus vulgaris L.) hypocotyl hook

Acetylcholine did not show a short-time effect on the extracellularbioelectric potential differences of etiolated bean (Phaseolusvulgaris L.) hypocotyls. Acetylcholine in the dark did not mimicany light effect but influenced the photoelectric responsesinduced by blue light. Hyperpolarization was inhibited by increasingthe acetylcholine concentration. This effect seemed to dependon the increasing hyperpolarization of the resting potentialof the hooks during incubation with acetylcholine. Potassiumchloride showed the same effect on the photoelectric responsebut in this case, we found a more positive resting potentialwith increasing salt concentrations. The potassium content ofhypocotyl hooks incubated in the dark in 0.2 M KCl solutionwith acetylcholine was significantly less than in the controls. (Received May 31, 1977; )     

Expression of Radiation-Induced Mutations at the Arginine Permease (CAN1) Locus in SACCHAROMYCES CEREVISIAE

In the yeast Saccharomyces cerevisiae, the expression of resistance to the L-arginine analog, L-canavanine, after mutagenesis, is strongly dependent on the metabolic state of the cell. The frequency of mutations recovered after exposure to ultraviolet light or X rays was measured under a variety of culture conditions. The results indicate that the frequency of mutants recovered is determined by the following three factors: (1) The potential mutants still possess enough permease activity to take up some of the cell poison, and some are therefore killed before they can express the mutant genotype. The sensitivity is strongly influenced by the endogenous free arginine, which is in turn influenced by the growth medium. (2) The rapid decay of the permease molecules and the inability of the potential mutants to resynthesize this protein results in a rapidly increasing change of expression when selection is delayed. (3) During the time when the permease activity is decaying, repair of the mutagen-induced damage appears to occur.     

Ultrastructural characterization of asexual cysts ofGonyaulax polyedra Stein (Dinoflagellata)

Summary In the bioluminescent dinoflagellateGonyaulax polyedra, the formation of asexual cysts was elicited either by addition of 5-methoxytryptamine or by transfer to short-day conditions under lower temperature and decreased light intensity. The resulting changes were followed in vivo by light microscopy, and analysed ultrastructurally by electron microscopy. Irrespective of the method of cyst induction, theca and flagella shedding and the formation of a cyst wall can always be observed as essential steps in this process. Despite the extremely low level of bioluminescence emitted from the cysts, some scintillons persist. Encystment is accompanied by organelle and substructure rearrangement. Although cysts induced by 5-methoxytryptamine or by short days closely resemble each other, electron microscopy reveals typical differences. In cysts obtained by treatment with 5-methoxytryptamine most chloroplasts are of the expanded type, extending to the central region, whereas only a few are compact and peripherally positioned. Cysts induced by shortdays predominantly contain chloroplasts of the compact type and contain large amounts of stored starch and lipids. Their ultrastructural organization therefore resembles that of mastigote cells during darkness.     

Microplates with integrated oxygen sensing for medium optimization in animal cell culture

A new approach using microtiter plate cultivation with on-line measurement of dissolved oxygen (DO) was applied for medium optimization of mammalian cell culture. Applying dynamic liquid phase balance, oxygen uptake rates were calculated from the DO level and used as an indicator for culture viability. The developed method was successfully applied to optimization of the concentration of glucose, glutamine and inorganic salts for cultivation of a Chinese Hamster Ovary (CHO) cell line. Using 2³ full factorial central composite design, the optimum medium composition could be identified in one single run. The concentration of inorganic salts had a significant influence on cultivation. The developed method exhibits high potential to improve procedures of medium optimization for animal cell cultivation by allowing the investigation of large sets of potentially important variables in short time and with reduced effort.     

Application d'une méthode d'analyse du territoire à partir de la situation des marqueurs graphiques à l'intérieur de la Péninsule Ibérique : le Tage International

This paper, analyses the graphic evidences of the boundaries of Tagus between Spain and Portugal from the perspective of the model defended by our team. This model proposes the existence of the relationship between graphic markers: paintings, engravings in the open air, decorations over dolmens and menhirs, understood as a compact ideological group fixed in the organization social system of European producing people and metallurgical that occupying this landscape. This argument attempt to verify the possibilities of applying a pre-defined model in an area in which have been developed investigation models, focused to study megalithic monuments, menhirs, habitational areas, paints and engravings that shows symbolic expressions of the tradition to justify the property of rich areas in natural resources in what metallurgical have a remarkable importance.     

Style v dans le bassin du Douro: Tradition et changement dans les graphies des chasseurs du Paléolithique Supérieur européen

The documentation of some figures of hoofed in Siega Verde on panels of palaeolithic style and its stylistic references in the whole south of Europe, constitutes the starting point of the reflection on the presence of style v in the outdoors sites of the peninsular occident. In the Douro's region exists a richer documentation than the habitual in Europe: the outdoors panels of Côa and Siega Verde, the engravings on palaeolithic figures of La Griega, the paintings with direct chronologies of Ojo Guareña, the decorated plaquettes of the level 4 of Fariseu and the pebbles and plaquettes of Estebanvela. Painting in the caverns, outdoors and cave engravings and mobile art, with good references of absolute chronology between 11,500 BP and 9000 BP that confirm the continuity of the Palaeolithic art. If we compare the data of the peninsular occident with those of the north, those of Levant and those that begin to be known in Andalusia, the coincidence of dates is astonishing. In the same way if we compare these ones with the dates of the South of France and Italy. The external art of the western facade of the Iberian Peninsula possesses not only a unite palaeolithic contrasted sequence but rather it also puts in evidence the reality of the recurrent and continued locations in the whole sector during 30,000 years.Above the 11,000 BP, the transformations of the hunter groups begin to be evident in the whole south of Europe and the graphics demonstrate these changes, with a progressive transformation of contents and style that leads to a bigger schematization. The interesting cohabitation among naturalism and schematism that demonstrate the direct dates of C¹⁴, apparent a progressive transformation that discards radical ruptures between the social and graphic world of the palaeolithic hunters and their heirs.     

Looking ahead at the potential benefits of biotechnology-derived allergen therapeutics

While biotechnology-derived allergen therapeutics show promise in improving the safety of immunotherapy, they may prove to have additional benefits in comparison to conventional allergenic extracts that deserve commentary. These issues range from product stability and compatibility to medical practice issues, which will be the focus of this article.     

The sym plasmid pRP2JI and at least two other loci of Rhizobium leguminosarum biovar phaseoli can confer resistance to infection by the virulent bacteriophage RL38

Abstract The virulent Rhizobium bacteriophage RL38 did not form plaques on R.leguminosarum by phaseoli but did so at high efficiency on a derivative of that strain lacking its symbiotic plasmid pRP2JI. Other strains with large deletions in pRP2JI which removed many nod and nif genes retained resistance to RL38, showing that the gene which confers phage resistance lies elsewhere on the plasmid. Although the wild-type strain of R. leguminosarum bv. phaseoli failed to plate RL38, it was possible to transduce chromosomal markers into this strain, indicating that the 'block' was not at an early stage in the infection process. Two different recombinant plasmids obtained from a clone bank of genomic DNA of R. leguminosarum bv. phaseoli , which appeared to have no DNA in common, both conferred resistance to RL38. Surprisingly, the DNA cloned in each of these plasmids did not originate from pRP2JI. Therefore, several different loci both on the Sym plasmid and elsewhere on the bacterial genome can be involved in conferring resistance to this bacteriophage.