Testing the potential seed availability in dung samples: comparison of two seedling emergence methods

To optimize the estimation of species composition and viable seed content of herbivore faeces and to make different approaches comparable, two seedling emergence methods are evaluated. The Ter Heerdt method (TH) employs concentrated samples, potentially increasing and accelerating seedling emergence, as shown for soil samples (95% of all seedlings emerged within 6 weeks). Samples are kept under controlled conditions (glasshouse or climate room). Secondly, a common garden method (CG) using unconcentrated samples so that seasonal changes could fulfill the germination requirements of a broad species spectrum (experiment duration approximately 15 months) was applied. The methods were tested by the use of sheep faeces samples, collected during a six-day grazing period in a threatened dry grassland (Allio-Stipetum capillatae).Both methods proved largely similar in species composition (QS=0.81) and viable seed content (QS=0.69). More species (e.g. monocotyls) and a higher seedling emergence of hard-seeded species (Fabaceae and Cistaceae) were found in the CG method. Besides a higher emergence of some small-seeded winter annuals, few other species emerged exclusively by use of the TH method. Nevertheless, all species detected by only one method were found in low individual numbers (4).Depending on research interest and availability of space and time, the most appropriate method can be chosen. If the main focus is on the species composition, unconcentrated faeces samples can be studied by CG. In case the overall viable seed content is more important and/or a shorter time period is available, TH serves as a suitable alternative.     

Antennal sucrose perception in the honey bee (Apis mellifera L.): behaviour and electrophysiology

Physiological mechanisms of antennal sucrose perception in the honey bee were analysed using behavioural and electrophysiological methods. Following sucrose stimulation of the tip of a freely moving antenna, the latency of proboscis extension was 320–340 ms, 80–100 ms after the first activity in muscle M17 controlling this response. When bees were allowed to actively touch a sucrose droplet with one antenna, contacts with the solution were frequent with durations of 10–20 ms and average intervals between contacts of approximately 40 ms. High sucrose concentrations led to short and frequent contacts. The proboscis response and M17 activity were largely independent of stimulus duration and temporal pattern. Taste hairs of the antennal tip displayed spike responses to sucrose concentrations down to at least 0.1%. The first 25 ms of the response were suitable for discrimination of sucrose concentrations. This time interval corresponds to the duration of naturally occurring gustatory stimuli. Sucrose responses between different hairs on the same antenna showed a high degree of variability, ranging from less than five to over 40 spikes per 0.5 s for a stimulus of 0.1% sucrose. This variability of receptor responses extends the dynamic range of sucrose perception over a large range of concentrations.     

Modulation of human mammary cell sensitivity to paclitaxel by new quinoline sulfonamides.

Sulfonamide derivatives of chloroquine and primaquine were synthesised and evaluated against both paclitaxel-sensitive and paclitaxel-resistant mammarian cancer cell lines. All derivatives exhibited at least 96% MDR reversal activity when co-administered with paclitaxel at 5 microM. The best compound, a chloroquine derivative, exhibited 99% MDR reversal activity when co-administered with paclitaxel at 1 microM. Molecular modelling studies reveal that these derivatives share a common pharmacophore with taxane MDR reversal agents.     

Isolation and characterization of 7S-beta1-globuline from human erythrocytes (author's transl)]

A new protein was isolated from lysates of washed human erythrocytes in a two step procedure using ionexchange chromatography and gel filtration. The protein has the electrophoretic mobility of a beta1-globulin. On ultracentrifugation the purified protein when dissolved in a 0.05 M phosphate buffer (pH 6.8), containing 0.2 M NaCl sediments with 6.88 S and shows a molecular weight of 150,000-180,000 daltons. In salt solutions with higher ionic strength the molecules dissociate reversibly into subunits which have a molecular weight of 40,000-45,000 daltons. The 7S-beta1-erythrocyte protein according to its behavior at ultracentrifugation, gel filtration and SDS poly-acrylamide gel electrophreses apparently is composed of 4 identical or similar subunits which are loosely held together by noncovalent bonds. Chemically the 7S-beta1-erythrocyte protein consists of 99% amino acids and 1% carbohydrates. The concentration of this protein in erythrocytes amounts to 250 mg per 100 ml packed red blood cells. The protein is not found in the membrane. In its physical, chemical and immunochemical properties the 7S-beta1-erythrocyte protein differs from all other well defined proteins and enzymes from human red cells thus far known.     

Die Chloroplastendrehung beiMougeotia

Summary Mougeotia cells with chloroplasts oriented in profile have been irradiated with small spots of monochromatic red polarized light in order to induce chloroplast movement.In these experiments, four factors have been varied: 1. the orientation of the vibration plane of the light in relation to the cell axis, 2. the localization of the spot, i. e. irradiation of the chloroplast or the cytoplasm, 3. the spot size, and 4. the duration of the irradiation.As a result of our experiments, we conclude that the photoreceptor molecules responsible for the light-induced chloroplast movement are localized in the cytoplasm.As the photoreceptor of this reaction is the well known phytochromesystem, we may assume that also in other plants the phytochrome is localized in the cytoplasm rather than in the chloroplast.

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Signal Recognition Particle-ribosome Binding Is Sensitive to Nascent Chain Length

The signal recognition particle (SRP) directs ribosome-nascent chain complexes (RNCs) displaying signal sequences to protein translocation channels in the plasma membrane of prokaryotes and endoplasmic reticulum of eukaryotes. It was initially proposed that SRP binds the signal sequence when it emerges from an RNC and that successful binding becomes impaired as translation extends the nascent chain, moving the signal sequence away from SRP on the ribosomal surface. Later studies drew this simple model into question, proposing that SRP binding is unaffected by nascent chain length. Here, we reinvestigate this issue using two novel and independent fluorescence resonance energy transfer assays. We show that the arrival and dissociation rates of SRP binding to RNCs vary according to nascent chain length, resulting in the highest affinity shortly after a functional signal sequence emerges from the ribosome. Moreover, we show that SRP binds RNCs in multiple and interconverting conformations, and that conversely, RNCs exist in two conformations distinguished by SRP interaction kinetics.     

Modulatory Effects of the Piccolo Genotype on Emotional Memory in Health and Depression

Major depressive disorder (MDD) has been associated with biased memory formation for mood-congruent information, which may be related to altered monoamine levels. The piccolo (PCLO) gene, involved in monoaminergic neurotransmission, has previously been linked to depression in a genome-wide association study. Here, we investigated the role of the PCLO risk allele on functional magnetic resonance imaging (MRI) correlates of emotional memory in a sample of 89 MDD patients (64 PCLO risk allele carriers) and 29 healthy controls (18 PCLO risk allele carriers). During negative word encoding, risk allele carriers showed significant lower activity relative to non-risk allele carriers in the insula, and trend-wise in the anterior cingulate cortex and inferior frontal gyrus. Moreover, depressed risk allele carriers showed significant lower activity relative to non-risk allele carriers in the striatum, an effect which was absent in healthy controls. Finally, amygdalar response during processing new positive words vs. known words was blunted in healthy PCLO+ carriers and in MDD patients irrespective of genotype, which may indicate that signalling of salient novel information does not occur to the same extent in PCLO+ carriers and MDD patients. The PCLO risk allele may increase vulnerability for MDD by modulating local brain function with regard to responsiveness to salient stimuli (i.e. insula) and processing novel negative information. Also, depression-specific effects of PCLO on dorsal striatal activation during negative word encoding and the absence of amygdalar salience signalling for novel positive information further suggest a role of PCLO in symptom maintenance in MDD.     

Somatosensory Abnormalities for Painful and Innocuous Stimuli at the Back and at a Site Distinct from the Region of Pain in Chronic Back Pain Patients

Chronic low back pain (CLBP) was shown to be associated with pathophysiological changes at several levels of the sensorimotor system. Changes in sensory thresholds have been reported but complete profiles of Quantitative Sensory Testing (QST) were only rarely obtained in CLBP patients. The aim of the present study was to investigate comprehensive QST profiles in CLBP at the painful site (back) and at a site distinct from their painful region (hand) and to compare these data with similar data in healthy controls. We found increased detection thresholds in CLBP patients compared to healthy controls for all innocuous stimuli at the back and extraterritorial to the painful region at the hand. Additionally, CLBP patients showed decreased pain thresholds at both sites. Importantly, there was no interaction between the investigated site and group, i.e. thresholds were changed both at the affected body site and for the site distinct from the painful region (hand). Our results demonstrate severe, widespread changes in somatosensory sensitivity in CLBP patients. These widespread changes point to alterations at higher levels of the neuraxis or/and to a vulnerability to nociceptive plasticity in CLBP patients.