ALBERT

Notes: Field studies were conducted in 1988 and 1989 to determine the phenology and growth of broomrape in sunflower as affected by crop sowing dates. The parasitic weed attachment was observed in sunflower plants with 6–7 leaves; later it was found throughout the vegetative and flowering period of the crop. O. cernua seedlings with shoot development extensive but subterranean were mainly observed at the early heading stage of sunflower. At this stage they were beginning to reduce sunflower plant growth as compared with non–parasitized plants. The emergence of broomrape began at the early flowering stage of the crop and was particularly abundant throughout this and the achene–filling stage. Generally, broomrape infection was much less at the first than at the second or third sunflower sowings, and caused less reduction in yield.The duration of the broomrape emergence period increased as sowing date was delayed. Since sunflower yield was higher at earlier sowing dates, early sowing may be recommended for sunflower crops in broomrape–infested areas under mild mediterranean climates. Effet de la date de semis sur les infections d'orobanche (Orobanche cernua Loefl.) en culture de tournesol (Helianthus annuus L.)Des études de plein champ ont été conduites en 1988 et 1989 pour déterminer comment la phénologie et la croissance des orobanches en culture de tournesol étaient affectées par les dates de semis de la culture. Le rattachement de 1'adventice parasite a été observeé chez les plantes de tournesol avec 6–7 feuilles; plus tard il était observé tout au long des périodes végétatives et de floraison de la culture.Des plantules d'O. cernua avec un développement de la tige important mais souterrain ont été principalement observées au stage bourgeon précoce du tournesol. A ce stade elles ont commencé & réquire la croissance du tournesol en comparaison avec des plantes non parasitées. La levée de 1'orobanche a commencé au début du stade de la floraison de la culture et a été particuliérement abondant pendant celle–ci et le stade remplissement des akénes. Généralement, l'infection d'orobanche a été beaucoup moins forte au premier qu'au second et troisiéme semis et a causé des baisses de rendement plus faibles.La durée de la période de levée des orobanches a augmenté quand le semis a été retardé. Puisque le rendement en tournesol a été plus élevé pour les dates de semis précoces, un semis précoce peut être recommandé pour le tournesol en zones infestées par les orobanches sous les climats méditerranéens. Die Bedeutung des Saattermins der Sonnenblume (Helianthus annuus L.) für den Befall mil der Sommerwurz (Orobanche cernua Loefl.) In Feldversuchen wurden 1988 und 1989 die PhÄnologie und das Wachstum der Sommerwurz in Sonnenblumenkulturen untersucht. Der Befall der Sonnenblumenpflanzen wurde im 6- bis 7-Blatt-Stadium festgestellt, aber auch später in der gesamten vegetativen und generativen Phase der Kulturpflanze. Keimpflanzen der Sommerwurz mit einer kräftigen, aber unterirdischen Sproßentwicklung wurden überwiegend im frühen Stadium der Blütenentwicklung der Sonnenblume beobachtet. In diesem Stadium begann die Wachstumshemmung der Sonnenblume. Zu Beginn der Blüte der Sonnenblume lief die Sommerwurz auf und war während dieses Entwicklungsstadiums und der folgenden Samenbildung besonders häufig anzutreffen. In der ersten Aussaat der Sonnenblume war der Befall allgemein geringer als in der zweiten oder dritten. Mit späterem Saattermin verlängerte sich die Keimungsperiode der Sommerwurz. Nachdem die Sonnenblume bei früherer Saat einem höheren Ertrag brachte, wird für mild-mediterrane Gebiete mit Befall von Sommerwurz eine frühe Aussaat empfohlen.

Notes: The M-92 technique is aimed at helping teenagers become aware of: (a) the relationships between certain classic determinants such as prestige, income, and job opportunities and their system of job aspirations and/or expectations; (b) the strong and weak points in their system of information about jobs; (c) the internal structure of their system of occupational representations; and (d) possible conflicts in values or discordancies between aspirations and expectations. From a theoretical standpoint the M-92 draws directly on Coombs (1975) and Gottfredson (1981). Methodologically, it is an extension of the Hammond et al. (1988) Social Judgement Theory to the case of pair comparisons. Several concrete examples of the M-92 in use are described.

Notes: Abstract The adenylate energy charge of cells of Myoococcus coralloides D has been measured during the different stages of its life cycle. The energy charge of the vegetative cells (0.8) did not change significantly either during glycerol-induced myxospore formation, or during germination of these myxospores. Fruiting body myxospores had a relatively high energy charge (0.65). The adenylate energy charge decreased slightly (from 0.82 to 0.65) throughout fruiting body development and returned to values of vegetative cells in the early hours of germination of fruiting body myxospores. The levels of adenine nucleotide in myxospores in desiccation conditions were similar to those before desiccation.

Notes: Abstract Azotobacter chroococcum cells exhibiting the capacity to take up nitrate actively could transport [14C]cyanate. This activity was dependent on the nitrogen source present in the culture medium, ammonium acting as a repressor and nitrate as an inducer. The uptake of cyanate required metabolic energy and was absent from A. Chroococcum TR1, a mutant strain lacking the nitrate transport system, but was present at wild-type levels in A. chroococcum E4, a mutant strain deficient in nitrate reductase. These results show that cyanate is transported by the nitrate permease in A. chroococcum and therefore [14C]cyanate may be useful as a nitrate analogue for studies on nitrate transport.

Notes: Abstract Exoglucanases (β-glucosidases) I and II secreted into the culture medium by Saccharomyces cerevisiae were purified from cell cultures harvested at the early exponential phase of growth in order to avoid contamination of the second by a new immunologically-related material. The amino acid composition of the purified enzymes was roughly the same. In addition, both exoglucanases exhibited an identical NH2-terminal sequence (50 residues). These results confirm our previous results about the identity of the protein moieties of both enzymes. Exoglucanase I appears to arise by elongation of one or both short oligosaccharides present in enzyme II.

Notes: A chlorate-resistant Azotobacter chroococcum strain, which we designate TR1, has been isolated after mutagenesis of the parent strain with ICR-191. After growth in a medium containing nitrate, the mutant strain exhibited activities of nitrogenase, nitrate reductase and nitrise reductase, and it did not take up nitrate efficiently. Induction of nitrite reductase in the mutant required a nitrate concentration higher than in the wild type. The results suggest that TR1 is not a regulatory mutant but a strain deficient in the process of nitrate transport into the cell.

Notes: Abstract Electron microscopy of preparations of the Myxocococcus coralloides D autolytic supernatants revealed the presence of phage-tail-like particles. The particles consisted of a core, a contractile sheath and a baseplate with fibers. The induction of the defective prophage occurred when the cultures reached the stationary phase, but the events occurring during induction did not lead to cell lysis. Particles nerver appeared during exponential growth. They were not observed when M. coralloides D grew on solid media, either. Purified samples of phage tails were able to inhibit most of the myxobacterial strains which were tested when the particles were in the extended state, but they were unable to multiply on the sensitive strains.

Notes: Abstract Electrophoretic analysis of outer membrane proteins showed that Salmonella typhi OmpC expression is not reciprocally regulated relative to OmpF as described for Escherichia coli and S. typhimurium. When bacteria were grown in minimal media, both OmpC and OmpF were repressed as the osmolarity increased. However, in Luria broth, expression of OmpC was slightly induced by osmolarity up to 0.3 osmM. Plasmids bearing E. coli ompC-lacZ or ompF-lacZ gene fusions were studied for their expression in S. typhi and E. coli. Under anaerobic growth conditions, expression of ompC-lacZ in S. typhi was maximal at 0.16 osmM, while in E. coli expression was maximal at 0.7 osmM. ompF-lacZ expression was similarly repressed by medium osmolarity and anaerobiosis in both species. In contrast, a drastic difference in the regulation of OmpF by temperature was observed; at 37 °C ompF-lacZ expression was repressed in E. coli. while in S. typhi it was induced.

Notes: Abstract In Chlamydomonas reinhardtii there are three glutamate dehydrogenase isozymes which can use both NADH and NADPH as cofactors and respond differently to different nitrogen sources and several stress conditions. From data of induction of isozymes in different metabolic situations, we propose a possible physiological role for each of them in algal carbon and nitrogen metabolism.