Revision of <Emphasis Type="Italic">Plasmopara</Emphasis> (Oomycota,Peronosporales) parasitic to <Emphasis Type="Italic">Impatiens</Emphasis>

The oomycete Plasmopara obducens was first described on wild Impatiens noli-tangere in Germany in 1877. About 125 years later the first occurrence of P. obducens on cultivated I. walleriana in the United Kingdom was reported, and a worldwide epidemic followed. Although this pathogen is a major threat for ornamental busy lizzy, the identity of the pathogen remained unconfirmed and the high host specificity observed for the genus Plasmopara cast doubts regarding its determination as P. obducens. In this study, using multigene phylogenies and morphological investigation, it is revealed that P. obducens on I. noli-tangere is not the conspecific with the pathogen affecting I. walleriana and another ornamental balsam, I. balsamina. As a consequence, the new names P. destructor and P. velutina are introduced for the pathogens of I. walleriana and I. balsamina, respectively.     

Protein-tyrosine phosphatase (PTP) wedge domain peptides: a novel approach for inhibition of PTP function and augmentation of protein-tyrosine kinase function

Inhibition of protein-tyrosine phosphatases (PTPs) counterbalancing protein-tyrosine kinases (PTKs) offers a strategy for augmenting PTK actions. Conservation of PTP catalytic sites limits development of specific PTP inhibitors. A number of receptor PTPs, including the leukocyte common antigen-related (LAR) receptor and PTPmu, contain a wedge-shaped helix-loop-helix located near the first catalytic domain. Helix-loop-helix domains in other proteins demonstrate homophilic binding and inhibit function; therefore, we tested the hypothesis that LAR wedge domain peptides would exhibit homophilic binding, bind to LAR, and inhibit LAR function. Fluorescent beads coated with LAR or PTPmu wedge peptides demonstrated PTP-specific homophilic binding, and LAR wedge peptide-coated beads precipitated LAR protein. Administration of LAR wedge Tat peptide to PC12 cells resulted in increased proliferation, decreased cell death, increased neurite outgrowth, and augmented Trk PTK-mediated responses to nerve growth factor (NGF), a phenotype matching that found in PC12 cells with reduced LAR levels. PTPmu wedge Tat peptide had no effect on PC12 cells but blocked the PTPmu-dependent phenotype of neurite outgrowth of retinal ganglion neurons on a PTPmu substrate, whereas LAR wedge peptide had no effect. The survival- and neurite-promoting effect of the LAR wedge peptide was blocked by the Trk inhibitor K252a, and reciprocal co-immunoprecipitation demonstrated LAR/TrkA association. The addition of LAR wedge peptide inhibited LAR co-immunoprecipitation with TrkA, augmented NGF-induced activation of TrkA, ERK, and AKT, and in the absence of exogenous NGF, induced activation of TrkA, ERK, and AKT. PTP wedge domain peptides provide a unique PTP inhibition strategy and offer a novel approach for augmenting PTK function.     

Balance training and exercise in geriatric patients

Objective measures of gait and balance which meet the criteria of reliability and validity are required as a basis for exercise regimens. We established reference values of clinically relevant locomotor and balance performances for geriatric patients. We are using these data for evaluating the effects of different therapeutic approaches to locomotor and balance disorders. Reference values for chair rising. We administered a battery of five tests concerning neuromuscular function, locomotion and balance to a sample of 212 participants without apparent locomotor deficits (139 women, 73 men, mean age 70,5 years, SD 6,78 , median 70 years, range 60 to 90 years, recruited by public announcements). The test battery comprised the 'chair rising test' for measuring lower extremity neuromuscular function (five repetitions of rising from a chair as quickly as possible with arms crossed over the chest). The test has been proven reliable, valid, sensible and predictive for falls and future locomotor status and ADL-status. Chair rising [sec/5x], Range: 5.4-19.4, Mean: 9.1 (women:9.2, men:9.0), SD: 1.97, Median: 8.9. Training of balance and muscle power with Galileo 2000 - preliminary results. Galileo is a device for whole body vibration/oscillatory muscle stimulation. The subject stands with bended knees and hips on a rocking platform with a sagittal axle, which thrusts alternatively the right and left leg 7-14 mm upwards with a frequency of 27 Hz, thereby lengthening the extensor muscles of the lower extremities. The reflexive reaction of the neuromuscular system is a chain of rapid muscle contractions. We conducted a randomized controlled trial, n=34 (age: mean 67y, range 61-85, 11 female), cross-over design, intervention group 2 months training program three times a week (each session 3x2 minutes), performance tests of all participants every two weeks). The first 19 subjects have finished the intervention period. They reached mean performance gains in chair rising of 18%, strikingly different to the constant values of the controls! We interpret the findings as improvements in muscle power by the oscillative muscle stimulation.     

Der Zinknachweis in den A-Zellen und B-Zellen des Inselorganes bei der Ente

Zusammenfassung In den Langerhansschen Inseln der Ente fällt die histochemische Reaktion auf Zink nach vitaler intravenöser Injektion von Dithizon stark positiv aus. Die überwiegend aus B-Zellen bestehenden hellen Inseln und die fast nur aus A-Zellen bestehenden dunklen Inseln erlauben den Ausfall der Reaktion und die Lokalisation des Zinkdithizonates innerhalb der Inselzellen in beiden Inselzelltypen getrennt zu beurteilen. Zinkdithizonat in granulärer Form findet sich sowohl in den A-Zellen als auch in den B-Zellen. Es ist in ersteren violettrot, in letzteren karminrot. In den A-Zellen deckt sich bei intravitaler Reaktion das Zinkvorkommen nicht mit den -Granula. Am nativen Gefrierschnitt ist das Metalldithizonat beim Zinknachweis nicht granulär, sondern diffus im ganzen Cytoplasma nachzuweisen. Das gleiche gilt für die B-Zellen. Die beiden Methoden haben lokalisatorisch einen verschiedenen Effekt. In beiden Zelltypen der Inseln wird außer dem roten Zinkdithizonat eine schüttere schwarze Körnelung gefunden, die möglicherweise das Vorhandensein eines weiteren Schwermetalles anzeigt. Das Vogelpankreas eignet sich in besonderem Maße für Untersuchungen, welche den Zinkgehalt der A-Zellen im Zusammenhang mit dem Kohlenhydratstoffwechsel betreffen.Mit Unterstützung der Research Corporation, New York.     

Maintaining the ionic permeability of a cellulose ester membrane

This paper reports the results of a series of experiments designed to test conditions that would permit NaCl to diffuse through 100 Da molecular weight cut-off (MWCO) and 1,000 Da MWCO membranes. For the 100 Da MWCO membrane, the membrane becomes completely impermeable to NaCl when dialyzed against distilled water (DW), but inclusion of one of a variety of different salts in the dialyzing solution maintains membrane permeability to NaCl. A titration experiment revealed that a minimum concentration of 0.1 mM of a salt such as KH2PO4 is required to sustain membrane permeability. In contrast, diffusion through the 1,000 Da MWCO membrane was slightly higher when DW was used as the dialysate. We conclude that the 100 Da MWCO membrane works well for a variety of dialysis applications provided that a maintenance salt is included in all dialyzing solutions.     

Alanine-stimulated exocytosis in<Emphasis Type="Italic"> Aplysia</Emphasis> enterocytes: effect of Na<Superscript>+</Superscript> transport and requirement for actin filaments

We used the Aplysia californica intestinal epithelium to investigate the effect of alanine-stimulated Na⁺ absorption on apical membrane exocytosis and whether stimulated exocytosis requires intact actin filaments. The fluid-phase marker fluorescein dextran was used to determine rates of apical membrane exocytosis. L-alanine significantly increased apical exocytosis by ~30% compared to controls, and there is a modest, positive correlation between alanine-stimulated exocytosis and short-circuit current (I _SC). Thus, apical exocytosis is modulated to some extent by the magnitude of Na⁺ and alanine entry across the apical membrane. Apical exocytosis is also responsive to virtually any increase in Na⁺ and alanine entry because increments in alanine-stimulated I _SC as small as 1 A/cm² stimulated exocytosis. We used D-alanine to determine which parameter (sensitivity to transport vs. magnitude of transport) was most important in activation of apical exocytosis. D-alanine-stimulated I _SC was one-sixth that of L-alanine, but stimulated exocytosis was only 29% less than that of L-alanine. Therefore, the apical exocytic system is more responsive to small increases in transport than to the magnitude of transport. Latrunculin A (Lat-A) disrupts the actin cytoskeleton and reduced constitutive apical exocytosis by ~65% and completely abolished alanine-stimulated exocytosis. Hence, constitutive exocytosis and alanine-stimulated exocytosis require actin filaments for recruitment of vesicles to the apical membrane. During nutrient absorption, actin filament-regulated apical exocytosis may represent a negative feedback system that modulates apical membrane tension.Abbreviations alaASW ASW containing alanine - C _m membrane capacitance - ASW artificial seawater - ETOH ethanol - fCa apical membrane fractional capacitance - FD fluorescein dextran - G _K plasma membrane potassium conductance - G _K,a apical membrane potassium conductance - HRP horseradish peroxidase - I _SC short-circuit current - J _Na transcellular net sodium flux - K _D dissociation constant - Lat-A latrunculin A - manASW ASW containing mannitol - PT proximal tubule - RFU relative fluorescence units - V _a apical membrane potential Communicated by L.C.-H. Wang     

Differential effects of exercise on aortic mitochondria

Routine exercise is widely recognized as cardioprotective. Exercise induces a variety of effects within the cardiovasculature, including decreased mitochondrial damage and improved aerobic capacity. It has been generally thought that the transient increase in oxidative stress associated with exercise initiates cardioprotective processes. Somewhat paradoxically, increased oxidative stress associated with cardiovascular disease (CVD) risk factors is thought to play an important role in the promotion and development of CVD. Hence, it is possible that CVD risk factors that increase oxidative stress (e.g., hypercholesterolemia) may modulate the cardioprotective effects of exercise. In this regard, the interaction between CVD risk factors and exercise on atherosclerotic lesion development and basal oxidant load is less defined. To determine the influence of preexistent hypercholesterolemia on cardioprotective effects of exercise, atherosclerotic lesion formation, oxidant load, mitochondrial damage, protein nitration (3-nitrotyrosine levels), and mitochondrial enzyme activities were determined in aortic tissues from normocholesterolemic (C57 control) and hypercholesterolemic [apoliprotein E-deficient (apoE(-/-))] mice after 16 wk of regular exercise. In normocholesterolemic mice, regular exercise was associated with decreased mitochondrial damage and oxidant load and increased SOD2 and adenine nucleotide translocator activities. Exercise did not decrease endogenous oxidant load and mitochondrial damage in hypercholesterolemic mice and did not reduce atherosclerotic lesion development. These data are consistent with the notion that CVD risk factors associated with increased oxidative stress can alter the benefits of exercise and that mitochondrial damage appears to be correlated with the cardiovascular effects of exercise.     

Copepod diapause and the biogeography of the marine lipidscape

Aim

One of the primary characteristics that determines the structure and function of marine food webs is the utilization and prominence of energy‐rich lipids. The biogeographical pattern of lipids throughout the ocean delineates the marine “lipidscape,” which supports lipid‐rich fish, mammal, and seabird communities. While the importance of lipids is well appreciated, there are no synoptic measurements or biogeographical estimates of the marine lipidscape. Productive lipid‐rich food webs in the pelagic ocean depend on the critical diapause stage of large pelagic copepods, which integrate lipid production from phytoplankton, concentrating it in space and time, and making it available to upper trophic levels as particularly energy‐rich wax esters. As an important first step towards mapping the marine lipidscape, we compared four different modelling approaches of copepodid diapause, each representing different underlying hypotheses, and evaluated them against global datasets.

Location

Global Ocean.

Taxon

Copepoda.

Methods

Through a series of global model runs and data comparisons, we demonstrated the potential for regional studies to be extended to estimate global biogeographical patterns of diapause. We compared four modelling approaches each designed from a different perspective: life history, physiology, trait‐based community ecology, and empirical relationships. We compared the resulting biogeographical patterns and evaluated the model results against global measurements of copepodid diapause.

Results

Models were able to resolve more than just the latitudinal pattern of diapause (i.e. increased diapause prevalence near the poles), but to also pick up a diversity of regions where diapause occurs, such as coastal upwelling zones and seasonal seas. The life history model provided the best match to global observations. The predicted global biogeographical patterns, combined with carbon flux estimates, suggested a lower bound of 0.031–0.25 Pg C yr^?1 of downward flux associated with copepodid diapause.

Main conclusions

Results indicated a promising path forward for representing a detailed biogeography of the marine lipidscape and its associated carbon flux in global ecosystem and climate models. While complex models may offer advantages in terms of reproducing details of community structure, simpler theoretically based models appeared to best reproduce broad‐scale biogeographical patterns and showed the best correlation with observed biogeographical patterns.

     

Characterization of an antibody-urokinase conjugate. A plasminogen activator targeted to fibrin

The plasminogen activator urokinase was linked covalently to a monoclonal antibody specific for the amino terminus of the beta chain of human fibrin by means of the unidirectional cross-linking reagent N-succinimidyl-3-(2-pyridyldithio)propionate. N-Succinimidyl-3-(2-pyridyldithio)propionate allowed the amino groups on urokinase to be coupled to the sulfhydryl groups on iminothiolane (which had been introduced into the antibody before the coupling reaction). The inter-heavy chain sulfhydryl of the Fab' of this antibody was also linked to N-succinimidyl-3-(2-pyridyldithio)propionate-substituted urokinase. The antibody- or Fab'-urokinase complexes were purified by two affinity chromatography steps. In the first, benzamidine was used as ligand for urokinase, in the second, a heptapeptide consisting of the 7 amino-terminal residues of the beta chain of fibrin (beta peptide) was used as ligand for the antibody. The activity of the purified conjugates was compared with that of urokinase alone in an assay measuring lysis of 125I-fibrin monomer covalently linked to Sepharose CL-4B. For any concentration of either urokinase alone or urokinase-antifibrin antibody conjugate, an equivalent amount of lysis (release of labeled peptide from fibrin monomer-Sepharose) was obtained with 1/250 the concentration (with respect to urokinase content) of antifibrin antibody-urokinase conjugate. The antifibrin Fab'-urokinase conjugate exhibited a similar enhancement of activity in comparison with urokinase. Enhanced fibrinolysis was fully inhibited by beta peptide. These results suggest that antibody targeting enhances the concentration of urokinase in the vicinity of immobilized fibrin monomer, thereby also increasing the local conversion of plasminogen to plasmin, which in turn degrades its substrate, fibrin. Univalent antigen-antibody binding is sufficient for optimal efficiency.     

Prothoracic DUM neurons of the cricket Gryllus bimaculatus — responses to natural stimuli and activity in walking behavior

Summary Responses to sensory stimuli and spike activity uring walking were investigated in bilaterally symmetrical dorsal unpaired median (DUM) neurons of the cricket. Intracellular recordings within the prothoracic ganglion were made either in restrained animals or in stationary walking specimens whilst parameters of their intended locomotion were measured. Three types of DUM cells were distinguished morphologically and physiologically. DUMa neurons send axons through segmental nerves. They often generated spontaneously large action potentials with low frequencies. Most DUMa neurons showed multimodal sensitivity, preferentially to cereal wind puffs and 15 kHz sound. Mean latencies ranged from 25 to 349 ms. Their large intraindividual variability could be correlated with behavioral modes during walking. Generally, the spike frequency increased with increased forward speed, while it was not related to turning. DUMb neurons projected either through the anterior or posterior connectives, but seemed physiologically similar to DUMa neurons. DUMc neurons were H-shaped with axons in both pairs of connectives. No external stimulus led to discrete spikes, but the regular spontaneous activity was modulated following cereal wind puffs to a restrained animal. During wind evoked escape the spike activity of another DUMc cell was modulated in phase with the rhythmic running behavior. The possibly different functions of DUMa and DUMc neurons during walking are discussed.