An SAR sequence containing 395 bp DNA fragment mediates enhanced,gene-dosage-correlated expression of a chimaeric heat shock gene in transgenic tobacco plants

A 395 bp fragment located downstream from the soybean heat shock geneGmhsp 17.6-L exhibits several characteristics of scaffold attachment region (SAR) sequences. It contains matrix consensus elements, a topoisomerase II binding sequence and it associates with the isolated nuclear scaffold of soybeanin vitro. Chimaeric genes containing the SAR_L fragment either at one side (5 or 3) or at both sides of a heat shock promoter-regulated -glucuronidase reporter gene were constructed. A five-to nine-fold increase of heat-inducible -glucuronidase activity was observed in transgenic tobacco plants containing constructs with SAR_L fragments either at both sides or with at least one SAR_L copy located upstream from the reporter gene. The gene copy number is positively correlated with the level of heat-inducible reporter gene activity in these. plants but positional effects are not entirely eliminated. Thus, SAR sequences may potentially be used to increase gene expression, via as yet unknown mechanisms, and to reduce adverse effects on the expression of multiple gene copies in transgenic plants.     

Obesity as a determinant for response to antihypertensive treatment.

OBJECTIVE--To test the hypothesis that beta blockers lower blood pressure more effectively than calcium entry blockers in obese hypertensive patients and that calcium entry blockers are more effective in lean patients. DESIGN--Double blind, randomised controlled trial of treatment over six weeks. SETTING--Tertiary referral centre. SUBJECTS--42 white men with uncomplicated mild to moderate essential hypertension (World Health Organisation stage I or II); 36 completed the study. INTERVENTION--Patients were randomised to metoprolol 50-100 mg twice daily or isradipine 2.5-5.0 mg twice daily for six weeks after a two week run in phase. MAIN OUTCOME MEASURE--Blood pressure after six weeks of treatment. RESULTS--When stratified according to treatment and presence of obesity (body mass index < or = 27 kg/m2), the mean (SD) fall in blood pressure in the beta blocker group was 24 (13)/18 (10) mm Hg in obese patients and 18 (19)/12 (13) mm Hg in lean patients. In the calcium entry blocker group, the fall in blood pressure was 21 (15)/17 (6) mm Hg in lean patients and 18 (11)/8 (10) mm Hg in obese patients. After taking age and blood pressure before treatment into account there was a significant interaction between obesity and drug therapy (p = 0.019) with a better diastolic blood pressure response to calcium entry blockers in lean patients and to beta blockers in obese hypertensive patients. CONCLUSION--Obesity affects the efficacy of metoprolol and isradipine in reducing blood pressure.     

Über schlauchförmige Ausstülpungen an der Zellmembran der Makrogametocyten von Eimeria perforans

Summary The surface of the gametocytes and gametes of Eimeria perforans reveals tube-like extrusions which have not been discovered so far in coccidia. These slender tubes are 650 Å in width and at least 1,3 in length. Probably they represent resorbing organelles. The tubes occur only at the surface of older female gametocytes and gametes and have not been observed in merozoites, schizonts, microgametocytes and male gametes. In transversal sections the tubes look like vesicles and are bordered by a membrane the layers of which are not sharply defined. The interior of the tubes seems to be empty after electron microscope observations. In longitudinal sections the membrane of the tubes is striated. The repeating unit of the dark and light bands amounts to about 165 Å. This appearance cannot be explained so far.

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Für beratende Hilfe sind wir Herrn Prof. Dr. R. Danneel und Herrn Prof. Dr. K. E. Wohlfarth-Bottermann zu Dank verpflichtet, für technische Unterstützung Fräulein cand. rer. nat. B. Volkmann. Herrn Dr. D. Spiecker von der Forschungsstelle für Jagdkunde und Wildschadenverhütung, Beuel, danken wir für die Durchführung der Infektionen. Die Mittel für die Untersuchungen stellte uns die Deutsche Forschungsgemeinschaft zur Verfügung.     

Automatic control of the extra-corporal bypass: system analysis, modelling and evaluation of different control modes.

Automatic control of the blood gas parameters during extracorporeal circulation has the potential to improve the quality of this procedure and to relieve the personnel from a time consuming task. This paper describes a model of the underlying system for a standard clinical set-up and pinpoints the major difficulties which are the variations of the process gains and the blood- and gas-flow dependent dead times and time constants. Scheduled PI-controllers both for the arterial oxygen as well as for the carbon dioxide partial pressure were designed. Scheduling was based on the blood flow rate. These controllers were tested in a simulation environment. The control systems remained stable under all tested operating condition, but if the blood flow rate was changed abruptly rather large load errors occurred. The performance was improved markedly by adding a feed-forward control path which directly influences the actuating signals based on the actual blood flow rate and the hemoglobin contents, variables which are measured anyway. The major conclusion of this study is to use such direct feed-forward compensation even if more sophisticated control algorithms are used.     

CU(II)-catalyzed oxidation of Alzheimer's disease beta-amyloid peptide and related sequences: remarkably different selectivities of neurotoxic betaAP1-40 and non-toxic betaAP40-1.

We investigated the CuII-catalyzed oxidation of beta-amyloid peptides betaAP10-20 and betaAP40-1 by tandem mass spectrometry and compared oxidation yields and selectivities to those for betaAP1-16, betaAP1-28 and betaAP1-40, which were obtained earlier (26). While betaAP1-16, betaAP1-28 and betaAP1-40 showed an almost exclusive oxidation of His residues to 2-oxo-histidine, the selectivity pattern is changed for betaAP10-20,which shows oxidation of His but also hydroxylation of Tyr and Phe. In contrast to betaAP1-40, the reverse sequence betaAP40-1 shows a strong selectivity for the hydroxylation of Tyr31 while only negligible His oxidation is observed at early time points. These selectivity patterns show the importance of the geometry of the metal-binding site for peptide/protein oxidation. The significantly different characteristic of betaAP1-40 and betaAP40-1 with regard to metal catalyzed processes may be related to the differences in the neurotoxic properties of these sequences.     

The intrinsic electrophysiological characteristics of fly lobula plate tangential cells: I. Passive membrane properties

The passive membrane properties of the tangential cells in the fly lobula plate (CH, HS, and VS cells, Fig. 1) were determined by combining compartmental modeling and current injection experiments. As a prerequisite, we built a digital base of the cells by 3D-reconstructing individual tangential cells from cobalt-stained material including both CH cells (VCH and DCH cells), all three HS cells (HSN, HSE, and HSS cells) and most members of the VS cell family (Figs. 2, 3). In a first series of experiments, hyperpolarizing and depolarizing currents were injected to determine steady-state I-V curves (Fig. 4). At potentials more negative than resting, a linear relationship holds, whereas at potentials more positive than resting, an outward rectification is observed. Therefore, in all subsequent experiments, when a sinusoidal current of variable frequency was injected, a negative DC current was superimposed to keep the neurons in a hyperpolarized state. The resulting amplitude and phase spectra revealed an average steady-state input resistance of 4 to 5 M and a cut-off frequency between 40 and 80 Hz (Fig. 5). To determine the passive membrane parameters R _m (specific membrane resistance), R _i (specific internal resistivity), and C _m (specific membrane capacitance), the experiments were repeated in computer simulations on compartmental models of the cells (Fig. 6). Good fits between experimental and simulation data were obtained for the following values: R _m = 2.5 kcm², R _i = 60 cm, and C _m = 1.5 F/cm² for CH cells; R _m = 2.0 kcm², R _i = 40 cm, and C _m = 0.9 F/cm² for HS cells; R _m = 2.0 kcm², R _i = 40 cm, and C _m = 0.8 F/cm² for VS cells. An error analysis of the fitting procedure revealed an area of confidence in the R _m -R _i plane within which the R _m -R _i value pairs are still compatible with the experimental data given the statistical fluctuations inherent in the experiments (Figs. 7, 8). We also investigated whether there exist characteristic differences between different members of the same cell class and how much the exact placement of the electrode (within ±100 m along the axon) influences the result of the simulation (Fig. 9). The membrane parameters were further examined by injection of a hyperpolarizing current pulse (Fig. 10). The resulting compartmental models (Fig. 11) based on the passive membrane parameters determined in this way form the basis of forthcoming studies on dendritic integration and signal propagation in the fly tangential cells (Haag et al., 1997; Haag and Borst, 1997).     

Geographic and between-generation variation in the parasitoid communities associated with an invading gallwasp,Andricus quercuscalicis (Hymenoptera: Cynipidae)

The knopper gallwasp Andricus quercuscalicis Burgsdorf 1783 (Hymenoptera: Cynipidae) has invaded western and northern Europe from southern and eastern Europe over the last 400 years. A. quercuscalicis has two alternating generations, which differ in phenology, structure, and host oak species. This study describes geographic variation in the community in the tiny catkin galls of the sexual generation on Turkey oak, Quercus cerris, and compares the patterns obtained with those in the community attacking the alternate agamic generation. As predicted from considerations of parasitoid recruitment to the communities of invading phytophagous insects (Cornell and Hawkins 1993), in its native range the sexual generation shows (1) higher parasitoid community species richness, (2) higher total mortality due to parasitoid attack and (3) a higher ratio of specialist to generalist parasitoid species than is evident in the invaded range. Counter to predictions, there is no indication that parasitoid community richness in the invaded range has increased with time since the arrival of the new host. Higher host mortality in the native range is due principally to a single specialist, Aulogymnus obscuripes Mayr 1877 (Hymenoptera: Eulophidae), and is not distributed evenly among parasitoid species which attack the gall-former only in this area. This contrasts with the community in Britain, where three principal generalist parasitoids cause approximately equal mortalities. The agamic gall contains a taxonomically and structurally diverse guild of parasitoid and inquiline species, associated with the changing resource provided by a large, long-lived, complex gall. In contrast, the sexual community includes a taxonomically and structurally narrow guild, associated with a resource which is structurally simple, small in size and short-lived. No parasitoid species attacks the gall-former in both generations. Surprisingly, in spite of these differences in the nature of the gall resource in the two generations, over their entire range (native and invaded) the parasitoid guilds of the two are equally species rich.     

Ribonuclease P from plant nuclei and photosynthetic organelles

RNase P consists of both protein and RNA subunits in all organisms and organelles investigated so far, with the exception of chloroplasts and plant nuclei where no enzyme-associated RNA has been detected to date. Studies on substrate specificity revealed that cleavage by plant nuclear RNase P is critically dependent on a complete and intact structure of the substrate. No clearcut answer is yet possible regarding the order of processing events at the 5 or 3 end of tRNAs in the case of nuclear or chloroplast processing enzymes. RNase P from a phylogenetically ancient photosynthetic organelle will be discussed in greater detail: The enzyme from theCyanophora paradoxa cyanelle is the first RNase P from a photosynthetic organelle which has been shown to contain an essential RNA subunit. This RNA is strikingly similar to its counterpart from cyanobacteria, yet it lacks catalytic activity. Properties of the holoenzyme suggest an intermediate position in RNA enzyme evolution, with an eukaryotic-type, inactive RNA and a prokaryotic-type small protein subunit. The possible presence of an RNA component in RNase P from plant nuclei and modern chloroplasts will be discussed, including a critical evaluation of some criteria that have been frequently applied to elucidate the subunit composition of RNase P from different organisms.Abbreviations RNase P Ribonuclease P - (pre-)tRNA transfer ribonucleic acid (precursor) - tRNA ^Ser (- ^Tyr , - ^Phe ) transfer ribonucleic acid specific for serine (tyrosine, phenylalanine) - CyRP RNA RNA component of cyanelle RNase P     

Excitatory and inhibitory responses caused by norepinephrine in duck subfornical organ neurons are mediated by β- and α 2-adrenoceptor activation

The responsiveness of spontaneously active neurons in the subfornical organ (SFO) of adult ducks to angiotensin II (ANGII), norepinephrine (NE), isoproterenol (Iso, -agonist), phenylephrine (Phe, ₁-agonist) and clonidine (Clo, ₂-agonist) was investigated in brain slices with extracellular recording technique. 64% (n=90) of the neurons increased their activity after superfusion with ANGII, the rest were unresponsive. Application of NE activated 10 and inhibited 8 neurons (n=22); the excitation being correlated with an excitatory ANGII responsiveness of the same neurons and the inhibition with the absence of an ANGII responsiveness. Iso activated 74% (n=58) and Clo inhibited 88% (n=16) of the investigated neurons. Phe did not have an effect on the majority (60%) of the neurons and produced both excitatory and inhibitory actions on the remaining cells. These results offer a plausible explanation for the dose dependent dipsogenic effect of Iso and the failure of NE to elicit dose dependent drinking, which can be explained by its dual, excitatory and inhibitory effect on SFO neurons. It is further concluded, that peripherally applied Iso exerts its dipsogenic action in high concentration by a direct excitatory effect on SFO neurons via the open blood brain barrier. Under physiological conditions, afferent neuronal input of still unknown origin might specifically modulate the activity of SFO neurons, because plasma concentrations of NE are probably not high enough to activate SFO neurons from the blood side of the blood brain barrier.Abbreviations ACSF artificial cerebrospinal fluid - ANGII angiotensin II - Clo clonidine - Iso isoproterenol - NE norepinephrine - NTS nucleus of the solitary tract - Phe phenylephrine - SFO subfornical organ