Ein Vogelruf, dessen Form sich im Jahresablauf ?ndert: der Verbeugungstriller bei der Brandente (Tadorna tadorna)

Zusammenfassung Der Verbeugungstriller männlicher Brandenten, eine epigame Lautäußerung, weist sowohl in syntaktischen wie auch phonetischen Parametern zyklische jahreszeitliche Veränderungen auf. Die Gesamtdauer der Lautäußerung vergrößert sich allmählich im Laufe des Frühjahrs. Dafür sind eine Verlängerung des tonalen Eingangselements und eine Vermehrung der Elemente der abschließenden Phrase verantwortlich. Dagegen verkürzt sich das 2. Element gleichzeitig. In allen untersuchten Elementen erhöht sich die Tonhöhe parallel zur Verlängerung des Rufes. Diese Veränderungen des Ausdrucksverhaltens geben vermutlich Änderungen innerer Zustandsgrößen wieder.

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Seasonally changing bird call: the trill call of male Shelducks (Tadorna tadorna)

Both syntactic and phonetic features of the trill call accompanying the whistle-shake in adult male Shelducks are subject to cyclic annual changes. In the course of spring, the duration of the whole call increases gradually. This is caused by a prolongation of the first call element and insertion of additive elements in the final phrase. In contrast the second element is shortened by about 10 ms. At the same time, the pitch of all measured elements is raised. These findings are discussed in the framework of hormonal regulation and communicative function.

     

Uptake,accumulation and metabolism of auxins in tobacco leaf protoplasts

Uptake and metabolism of exogenous naphthalene-1-acetic acid (NAA) and indole-3-acetic acid (IAA) have been studied in tobacco (Nicotiana tabacum L. cv. Xanthi) mesophyll protoplasts. Both auxins entered protoplasts by diffusion under the action of the transmembrane pH gradient without any detectable participation of an influx carrier. Molecules were accumulated by an anion-trapping mechanism and most of them were metabolized within hours, essentially as glucose-ester and amino-acid conjugates. Protoplasts were equipped with a functional auxin-efflux carrier as evidenced by the inhibitory effect of naphthylphtalamic acid on IAA efflux. Basically, similar mechanisms of NAA and IAA uptake occurred in protoplasts. However, the two auxins differed in their levels of accumulation, due to different membrane-transport characteristics, and the nature of the metabolites produced. This shows the need to estimate the accumulation and the metabolism of auxins when analyzing their effects in a given cell system. The internal auxin concentration could be modulated by changing the transmembrane pH gradient, giving an interesting perspective for discriminating between the effects of intra- and extracellular auxin on physiological processes.Abbreviations BA benzoic acid - C_i/C_e accumulation ratio of auxin - IAAasp N-[3-indolylacetyl]-dl-aspartic acid - NAA naphthalene-1-acetic acid - NAAasp N-[1-naphthylacetyl]-l-aspartic acid - NPA N-1-naphthylphthalamic acid The authors thank Dr. M. Caboche (I.N.R.A, Versailles, France) for his generous gifts of some amide derivatives of 1-NAA, Mr. P. Varennes and Dr. B. Das (I.C.S.N., C.N.R.S., Gif-sur-Yvette, France) for recording and interpreting the mass spectra of NAA glucose ester, and Prof. P. Manigault (Institut des Sciences Végétales, Gif-sur-Yvette) for microscopy measurements of protoplast dimensions. This work was supported by funds from the C.N.R.S, I.N.R.A, and E.E.C.     

DNA stainability with base-specific fluorochromes: dependence on the DNA topology in situ

The influence of DNA topology on stainability with the externally binding fluorochromes Hoechst 33258 (HO) and mithramycin (MI) was investigated in HeLa nuclei in comparison with the intercalating dye propidium iodide (PI). Changes in DNA topology were induced with a mild DNAse I treatment. Stainability properties of untreated and nuclease-treated nuclei were compared with those of the supercoiled-circular and the relaxed-linear forms of the plasmid pBR322. DNAse-treated nuclei stained with HO showed a higher fluorescence intensity than control samples, independently of the dye concentration, in contrast with the findings obtained with PI. Similar behaviour was observed with the relaxed-linear form of pBR322, compared with the supercoiled-circular molecule. With MI, the stainability of HeLa nuclei did not depend on the DNA topology, whereas the stainability of the plasmid was similar to that of HO. In order to assess whether this discrepancy depended on differences in the availability of DNAse-sensitive sites to the fluorochromes, fluorescence resonance energy transfer (FRET) studies were performed in nuclei stained with HO+PI, or with HO+MI dye pairs. After DNAse I digestion, the relative FRET efficiency between donor (HO) and acceptor molecules (PI or MI) was reduced significantly only when MI was the acceptor. This result may be due to greater stainability of DNAse-sensitive sites with HO than with MI. These findings indicate that DNA stainability with base-specific fluorochromes may be affected by the topology of chromatin regions.     

Modeling the alcoholic fermentation of xylose by Pichia stipitis using a qualitative reasoning approach

Qualitative Reasoning is a set of Artificial Intelligence theories, methods, and techniques that provide an answer to modeling problems in domains in which one can have a clear notion of how a system is functioning without being able to express it as classical mathematical equations, and where is posed the problem of using jointly quantitative and qualitative data, as well as processing a big amount of complex knowledge. SIMAO (a System to Interpret Measurements And Observations) is an attempt to deal with such problems. Although primarily devised for heterogeneous data interpretation in hydroecology, it was thought possible to use SIMAO in a wider context, like biotechnological processes. Starting from specific problems posed by a batch fermentation, the D-xylose conversion into ethanol by the yeast Pichia stipitis, this paper describes how was built and used a SIMAO model aimed at predicting the fermentation issue from initial conditions, i.e. set-points values and substrate concentration.List of Symbols QS quantity space - {pp, p, m, f, ff} quantity space elements - TR-m measurement translation rule - TR-o observation translation rule - TR-q qualitative transfer rule - incr, decr, inv primitive unary operators - [+], [-], [], [/] primitive binary operators     

Bioguided Fractionation and Isolation of an Antiplasmodial Saponin from the Roots of Nauclea xanthoxylon (A.Chev.) Aubrév. (Rubiaceae)

The root extract of Nauclea xanthoxylon (A.Chev.) Aubrév. displayed significant 50 % inhibition concentration (IC₅₀s) of 0.57 and 1.26 μg/mL against chloroquine resistant and sensitive Plasmodium falciparum (Pf) Dd2 and 3D7 strains, respectively. Bio-guided fractionation led to an ethyl acetate fraction with IC₅₀s of 2.68 and 1.85 μg/mL and subsequently, to the new quinovic acid saponin named xanthoxyloside ( 1 ) with IC₅₀s of 0.33 and 1.30 μM, respectively against the tested strains. Further compounds obtained from ethyl acetate and hexane fractions were the known clethric acid ( 2 ), ursolic acid ( 3 ), quafrinoic acid ( 4 ), quinovic acid ( 5 ), quinovic acid 3-O-β-D-fucopyranoside ( 6 ), oleanolic acid ( 7 ), oleanolic acid 3-acetate ( 8 ), friedelin ( 9 ), β-sitosterol ( 10a ), stigmasterol ( 10b ) and stigmasterol 3-O-β-D-glucopyranoside ( 11 ). Their structures were characterised with the aid of comprehensive spectroscopic methods (1 and 2D NMR, Mass). Bio-assays were performed using nucleic acid gel stain (SYBR green I)-based fluorescence assay with chloroquine as reference. Extracts and compounds exhibited good selectivity indices (SIs) of >10. Significant antiplasmodial activities measured for the crude extract, the ethyl acetate fraction and xanthoxyloside ( 1 ) from that fraction can justify the use of the root of N. xanthoxylon in ethnomedicine to treat malaria.     

Attempts to Determine the Roles of Visual and Olfactory Inputs in Initial Orientation and Homing of Pigeons over Familiar Terrain

The role of familiar visual landmarks in pigeon homing is still unsettled. If they are involved, they must be thought to be utilized in parallel with olfactory signals. In order to recognize the effectiveness of either one of the input channels separately, vision and olfaction, it is therefore necessary to interfere with both of them. Pigeons were temporarily deprived of image vision by spectacles made of translucent white paper, producing a condition called V^- as compared with the largely unimpaired condition V⁺. Access to olfactory signals was temporarily prohibited by charcoal filters before release and nasal anaesthesia upon release, resulting in condition O^- versus unimpaired smelling of natural air in O⁺. Prior to the test releases, all the participating pigeons had been made familiar with the two or four test sites (and with other sites in the area) by training flights. According to decreasing levels of initial homeward orientation and homing performance, the four combinations of treatments are to be arranged in the following order: V⁺O⁺, V⁺O^-, V^-O⁺, V^-O^-. In the last type, no trace of initial homeward orientation remained, indicating that at least one of the two input channels need be functional to enable home-related orientation. Over well known terrain, either alone seems to be more or less sufficient. The results are indicative but not definitely conclusive. Effects of visual impairment on behavioural activities in general cannot clearly be separated from orientation-specific effects. Therefore, and because many pigeons refuse to fly in V^- condition or fail to provide useful data, we stopped applying this method.     

Effect of maternal fatty acid deficiency on lipid content and composition of rat liver during prenatal development

Two groups of female rats were fed a diet with high (5.9 cal % of linoleate + linolenate) or low (0.78 cal % of linoleate + linolenate) essential fatty acid (EFA) concentration. The effects of the EFA concentration during gestation on liver lipid and fatty acid composition were studied in the fetuses at 15 and 20 days of intrauterine life. Fetal and liver weights were identical in the two groups; at day 20 the contents of proteins, total cholesterol, phospholipids and glycolipids were significantly decreased (p less than 0.01) with the low EFA diet while at day 15 only total cholesterol was affected (p less than 0.05). At both gestational ages the triacylglycerol content was increased in the low EFA group (day 15 p less than 0.05, day 20 p less than 0.01). The maternal EFA deficiency resulted in higher levels of 16:1 n-7 in the phospholipid fractions and 16:1 n-7 and 18:1 n-7 in the neutral lipids. The increase in these monoenoic derivatives partially compensated the decrease of the polyunsaturated species 18:2 n-6 and 20:4 n-6. In conclusion the low EFA diet results in important modifications of the fetal hepatic lipids during intrauterine development.     

Selection of peptides inhibiting a beta-lactamase-like activity.

A library of random peptide sequences was used to select peptides that inhibit an anti-idiotypic catalytic Ig, immunoglobulin (IgG) 9G4H9, with a beta-lactamase-like activity. This library displays cyclic heptapeptides on the surface of bacteriophages and represents a collection of up to 4.5 x 109 peptides. The first selection step aimed at enriching the library in species that bind to the whole Ig molecule. The second step was to discriminate peptides that bind to part of the molecule other than the active site. Selected peptides were then screened by surface plasmon resonance analysis. Those displaying measurable Kd values were assayed for their ability to inhibit the catalytic Ig.