Two new C-methylated flavonoids from Myrica gale

From the leaves of Myrica gale 2′,4′-dihydroxy-6′-methoxy-3′,5′-dimethylchalcone has been isolated. The fruits yielded 2′-hydroxy-4′,6′-dimethoxy-3′-methyldihydrochalcone. The constitutions were deduced from spectroscopic data and confirmed by synthesis.     

Initial phases of indoleacetic acid induced growth in coleoptile segments of Avena sativa L.

The intial phases of auxin-induced growth in coleoptile segments of Avena sativa L. were investigated using a high resolution growth recording technique, based on an angular position sensing transducer. The first response to the hormone is a slight, transient reduction of the growth rate lasting about 5 min. After this phase growth rate increases to a maximum. The duration of the increase and the maximum clearly depend on the concentration of the hormone. With increasing auxin concentration the duration of the growth rate increase is reduced from about 80 min in 10^-9 M indoleacetic acid (IAA) to about 14 min in 10^-4 M IAA. After the maximum the growth rate declines. Looking at the maximum of the growth rate, we obtained a dose-response curve with a sharp increase between 10^-9 M and 10^-6 M IAA and a slight decline between 10^-6 M and 10^-4 M IAA. This result is confirmed by growth rates measured one and two hours after the application of the hormone.Abbreviations IAA indoleacetic acid     

Ontogenetische Verhaltens?nderungen bei der Brandente (Tadorna tadorna): Schlafen, Tauchen, Nahrungserwerb

Zusammenfassung Brandentenküken verfügen über drei verschiedene Taucharten, die sich nach Ausführung und Tauchdauer deutlich unterscheiden lassen. Während das Nahrungstauchen in der 6. Lebenswoche eingestellt wird, bleiben Tauchbaden und Fluchttauchen lebenslang erhalten. Neben dem Nahrungstauchen werden weitere Techniken des Nahrungserwerbs in Abhängigkeit vom Nahrungsangebot und dem Entwicklungsstand unterschiedlich häufig angewendet. Der zeitliche Aufwand für die Nahrungsaufnahme ist in den ersten 2 Lebenswochen maximal. Anschließend nimmt er, bei schneller als bei kontinuierlich ab. Kälteperioden führen zu einer weiteren Reduzierung. Die Schlafhäufigkeit sinkt nach einer anfänglichen Zunahme (bis 10. Lebenswoche) ab. Kälteperioden bewirken eine Zunahme. Unter 3 verschiedenen Schlafhaltungen wird bis zur 12. Lebenswoche das Schlafen im Liegen bevorzugt. Danach nimmt es zugunsten des einbeinigen Schlafens im Stehen, das erstmals in der 7. Lebenswoche auftritt, ab. Kälteperioden stellen die ursprünglichen Häufigkeitsverhältnisse zwischen beiden Schlafhaltungen wieder her. Brandentenküken bilden in den ersten Lebenswochen Schlafhaufen. Ihre Häufigkeit sinkt bis zur 12. Lebenswoche kontinuierlich auf Null ab.

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Ontogenetic changes in sleeping, diving and foraging behaviour in Shelduck (Tadorna tadorna) ducklings

Summary Shelduck ducklings show different types of diving behaviour: diving for food, flight-diving and dashing and diving in comfort situations. These types differ by diving duration and the behaviour of the ducks. In diving for food diving duration and frequency decrease during the first 6 weeks. After this, no food diving was observed. Other feeding methods include sieving, upending, pecking on the surface of water, feeding on plants and foot-trampling. Except for feeding on plants, which was first observed in the 10th week, all feeding methods are present in one day old ducklings. The share of foraging time is highest during the first 2 weeks of life. Afterwards it decreases (in females faster than in males) from about 50 to 20 %. During cold weather, it was still lower whereas resting and sleeping behaviour increased. After an increase during the first 10 weeks of life, the share of resting decreases to 25–40 % of observation time. Shelduck ducklings have 3 different sleeping postures: lying, standing on one leg, standing on two legs. During the first weeks of life ducklings only sleep standing on two legs or lying on the ground, the latter is being clearly preferred. Standing on one leg appeared in the 7th week. Its frequency increased and it became the most prominent resting pattern. Only during cold spells shelducks do return to sleep by lying on the ground. Under such conditions also sleeping in contact with one another reoccurs, which is typical for ducklings during their first weeks of life.

     

The NAM8 gene in Saccharomyces cerevisiae encodes a protein with putative RNA binding motifs and acts as a suppressor of mitochondrial splicing deficiencies when overexpressed.

Summary We have characterized the nuclear geneNAM8 inSaccharomyces cerevisiae. It acts as a suppressor of mitochondrial splicing deficiencies when present on a multicopy plasmid. The suppressed mutations affect RNA folding and are located in both group I and group II introns. The gene is weakly transcribed in wildtype strains, its overexpression is a prerequisite for the suppressor action. Inactivation of theNAM8 gene does not affect cell viability, mitochondrial function or mitochondrial genome stability. TheNAM8 gene encodes a protein of 523 amino acids which includes two conserved (RNP) motifs common to RNA-binding proteins from widely different organisms. This homology with RNA-binding proteins, together with the intronic location of the suppressed mitochondrial mutations, suggests that the NAM8 protein could be a non-essential component of the mitochondrial splicing machinery and, when present in increased amounts, it could convert a deficient intron RNA folding pattern into a productive one.     

Pulse-modulated photoacoustic measurements reveal strong gas-uptake component at high CO2-concentrations

The effect of high CO₂-concentration on photoacoustic signals from tobacco leaves is studied by means of a recently developed pulse modulation method which provides simultaneous information on photothermal and photobaric components in the millisecond time domain. High CO₂-concentrations are found to induce large gas-uptake signals. Simultaneous measurements of chlorophyll fluorescence suggest that the uptake signals are correlated with energy-dependent fluorescence quenching. Very similar CO₂-concentration dependencies are found in the absence and presence of methylviologen, which is known to catalyze O₂-reduction, and in the presence of glyceraldehyde, which blocks Calvin cycle and photorespiration. It is suggested that the CO₂-enhanced uptake signal is likely to reflect O₂-uptake in the Mehler reaction. However, it is not ruled out that also rapid CO₂-solubilisation or CO₂-binding caused by light-induced stroma alkalisation are involved. Strong uptake is also induced when the CO₂-concentration in the closed photoacoustic chamber increases due to dark-respiration. The consequences of these findings with respect to the interpretation of photoacoustic data (e.g., low-light effect) and to the regulatory role of O₂-dependent electron flow are discussed.     

The flow of jelly within a honeybee colony

Summary The flow of jelly from 100 nurse bees to the members of two normal-sized colonies was measured during one night. To follow the flow, nurses were injected with ¹⁴C-phenylalanine. They incorporated this label into the protein of their hypopharyngeal (brood food) glands and their own body protein. When they were allowed trophallactic contacts during the investigation period a loss of label and a shift away from the abdomen was observed, indicating protein synthesis in the hypopharyngeal glands from previously stored protein. Very young larvae were fed less frequently than older ones. Younger workers received larger amounts of jelly than older ones, but considerable amounts were given to foragers. Drones behaved similarly. Between one-third and one-half of the distributed jelly was given to imagines; 10% and 16% of all workers received radioactive jelly from 100 nurses in the two colonies during one night. Thus, jelly is a very important food for adult honey bees. There was a remarkable exchange of label within the class of nurses themselves that is interpreted as communication within the social system.Abbreviation dpm decays per minute