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Background Utilization of energy crops for biogas production has been controversially discussed in Germany due to negative environmental effects and the “food vs. fuel” debate. This led to a search for alternative substrates focusing on material from landscape management measures. Aquatic biomass is harvested during water body management, yet it has not been considered for energy generation. Methods The information where and which amount of biomass is collected by aquatic de-weeding operations in rivers and lakes was gathered via a nationwide survey. In addition to that, the amount of aquatic plant biomass potentially available in water bodies was estimated exemplarily for the flowing waters of Baden-Württemberg—by using data from the European Water Framework Directive surveys. Results The survey revealed 172 locations of de-weeding operations in flowing waters and 93 in standing waters. These locations are concentrated in lowland rivers of the North German Plain as well as the Upper Rhine Plain. Standing water de-weeding operations were reported mainly from the foothills of the Alps. The overall amount of biomass harvested per year is 36,244 t of fresh biomass. Taking into account missing data, a maximum of 100,000 t of fresh biomass per year can be estimated for Germany. The case study on plant biomass de-weeded from waters in Germany revealed that only a small part of the total aquatic plant biomass is actually harvested. Conclusions The amount of biomass harvested and removed from water bodies in Germany is considerably lower than the harvest of other substrates from landscape management measures such as mowing of meadows or trimming of trees and hedges. However, larger amounts are accumulating locally, concentrated in some regions or at specific water bodies, e.g., reservoirs, for which regional value chains could be established. In order to make the exploitation of these local potentials economically viable, changes regarding the economic and technological framework are required.

The Danube is the second-longest river in Europe that is subjected to various man-made alterations, including those related to hydro-power plants. We surveyed and analyzed the presence and abundance of macrophytes in the main channel from 2582 river kilometers (rkm) to 171 rkm. We also assessed selected habitat parameters in the sampled river stretches. Sixty-eight different plant species were recorded along the entire course. Among neophytes, we found Elodea nuttallii, E. canadensis, Vallisneriaspiralis and Azolla filiculoides. Based on similarity analysis, we distinguished 15 plant communities, most of which were defined as associations, which were classified into 5 alliances and represented three vegetation classes, namely vegetation of rooted hydrophytes Potamogetonetea, the vegetation of pleustophytes Lemnetea and vegetation of marshes Phragmitetea. The number and abundance of plant species, as well as plant communities recorded in single stretches, varied along the course. Canonical correspondence analysis (CCA) revealed that environmental parameters explained 21% of plant species composition. CCA runs with neophytes explained 41% of the variance, and current velocity, water transparency, species number and bank structure were significant variables. The present study revealed that the free-running sections of the river are poor in number and abundance of plant species, whereas impounded reaches mainly show an opposite result.

Sporadic inclusion body myositis (sIBM) contains non-necrotic myofibers that are surrounded and/or invaded by inflammatory cells. In this study we aimed to identify selective molecules that are present at this site. Myofibers of four biopsies of sIBM that were surrounded and/or invaded by inflammatory cells were microdissected, pooled and profiled by proteomic studies using mass spectrometry. Normal skeletal muscle tissue served as control. Based on the table of proteins that were detected in sIBM only, we selected nine extracellular matrix molecules and validated the results performing immunofluorescence. Seven out of nine proteins that were detected in sIBM by mass spectrometry showed different immunohistochemical results in myositis and normal controls. Of these, the small leucine-rich repeat proteins proline arginine-rich end leucine-rich repeat protein (PRELP) and biglycan were deposited precisely at myofibers surrounded and/or invaded by inflammatory cells both in sIBM and polymyositis. The basement membrane (BM) molecules merosin, perlecan, nidogen-2 and collagen IV were variably destroyed or increased at these sites. P component, which ensheathed all myofibers in normal controls, was absent from invaded myofibers. Similar to BM remodeling, the specific deposition of PRELP and biglycan may represent a mechanism to defend against immune attack. Loss of P component may affect the anchorage of the myofiber in the endomysium.

Stable Isotope Labeling by Amino Acids in Cell Culture (SILAC) is a widespread method for metabolic labeling of cells and tissues in quantitative proteomics; however, incomplete incorporation of the label has so far restricted its wider use in plants. Here, we argue that differential labeling by two different versions of the labeled amino acids renders SILAC fully applicable to dark-grown plant cell lines. By comparing Arabidopsis thaliana cell cultures labeled with two versions of heavy Lys (Lys-4 and Lys-8), we show that this simple modification of the SILAC protocol enables similar quantitation accuracy, precision, and reproducibility as conventional SILAC in animal cells.

Root hairs are unicellular extensions of specialized epidermis cells. Under limiting conditions, they significantly increase the water and nutrient uptake capacity of plants by enlarging their root surface. Thus far, little is known about the initiation and growth of root hairs in the monocot model species maize. To gain a first insight into the protein composition of these specialized cells, the 2573 most abundant proteins of maize root hairs attached to four-day-old primary roots of the inbred line B73 were identified by combining 1DE with nanoLC-MS/MS in a shotgun proteomic experiment. Among the identified proteins, homologues of 252 proteins have been previously associated with root hair formation and development in other species. Comparison of the root hair reference proteome of the monocot species maize with the previously published root hair proteome of the dicot species soybean revealed conserved, but also unique, protein functions in root hairs of these two major groups of flowering plants.

Heterosis describes the superior performance of heterozygous F(1)-hybrid plants compared to their homozygous parental inbred lines. In the present study, heterosis was detected for length, weight, and the time point of seminal root primordia initiation in maize (Zea mays L.) embryos of the reciprocal F(1)-hybrids UH005xUH250 and UH250xUH005. A two-dimensional gel electrophoresis (2-DE) proteome survey of the most abundant proteins of the reciprocal hybrids and their parental inbred lines 25 and 35 days after pollination revealed that 141 of 597 detected proteins (24%) exhibited nonadditive accumulation in at least one hybrid. Approximately 44% of all nonadditively accumulated proteins displayed an expression pattern that was not distinguishable from the low parent value. Electrospray ionization-tandem mass spectrometry (ESI-MS/MS) analyses and subsequent functional classification of the 141 proteins revealed that development, protein metabolism, redox-regulation, glycolysis, and amino acid metabolism were the most prominent functional classes among nonadditively accumulated proteins. In 35-day-old embryos of the hybrid UH250xUH005, a significant up-regulation of enzymes related to glucose metabolism which often exceeded the best parent values was observed. A comparison of nonadditive protein accumulation between rice and maize embryo data sets revealed a significant overlap of nonadditively accumulated proteins suggesting conserved organ- or tissue-specific regulatory mechanisms in monocots related to heterosis.

Summary Bacillus subtilis BY-kinase PtkA was previously shown to phosphorylate, and thereby regulate the activity of two classes of protein substrates: UDP-glucose dehydrogenases and single-stranded DNA-binding proteins. Our recent phosphoproteome study identified nine new tyrosine-phosphorylated proteins in B. subtilis. We found that the majority of these proteins could be phosphorylated by PtkA in vitro. Among these new substrates, single-stranded DNA exonuclease YorK, and aspartate semialdehyde dehydrogenase Asd were activated by PtkA-dependent phosphorylation. Because enzyme activity was not affected in other cases, we used fluorescent protein tags to study the impact of PtkA on localization of these proteins in vivo. For several substrates colocalization with PtkA was observed, and more importantly, the localization pattern of the proteins enolase, YjoA, YnfE, YvyG, Ugd and SsbA was dramatically altered in ΔptkA background. Our results confirm that PtkA can control enzyme activity of its substrates in some cases, but also reveal a new mode of action for PtkA, namely ensuring correct cellular localization of its targets.

Lateral roots are all roots that are initiated in the pericycle cell layer of other roots during postembryonic development. The maize (Zea mays L.) mutant rum1 (rootless with undetectable meristems 1) does not initiate lateral roots in the primary root. In the present study, two-dimensional electrophoresis proteome profiles of three biological replicates of pericycle cells isolated from the differentiation zone of 2.5-day-old wild-type and rum1 primary roots were generated. This early developmental stage was selected in order to analyze histologically similar cells before the initiation of lateral roots in wild-type primary roots. In total, 418 proteins were reproducibly detected on all six gels after fluorescent staining with Flamingo dye. Among those, twelve proteins were differentially accumulated between wild-type and rum1 pericycle cells (Fc > 2; p < 0.05). Electrospray ionization tandem mass spectrometry (ESI-MS/MS) identified eight of the twelve proteins. Six proteins were related to metabolism, one protein belonged to the class of disease and defense, and one protein was related to development. Six of the eight proteins have not been previously localized to the pericycle. Moreover, the slight overlap between proteins and transcripts that are differentially accumulated in the maize pericycle between wild-type and rum1 underscores the importance of posttranscriptional protein modifications that cannot be detected on the RNA level. The differential accumulation of proteins in rum1 and wild-type pericycle cells of the primary root suggests that the abundance of these proteins could be regulated by RUM1.

The spread of Gram-negative bacteria with plasmid-borne extended-spectrumβ-lactamases (ESBLs) has become a worldwide problem. This study analysed a total of 366 ESBL-producingEnterobacteriaceaestrains isolated from non-selected patient specimens at the university hospital of Tübingen in the period January 2003 to December 2007. Although the overall ESBL rate was comparatively low (1.6 %), the percentages of ESBL-producingEnterobacterspp. andEscherichia coliincreased from 0.8 and 0.5 %, respectively, in 2003 to 4.6 and 3.8 % in 2007. In particular, the emergence was observed of one carbapenem-resistant ESBL-producingE. coliisolate and five carbapenem-non-susceptible ESBL-positiveKlebsiella pneumoniaeisolates, in two of which carbapenem resistance development was documentedin vivounder a meropenem-containing antibiotic regime. The possible underlying mechanism for this carbapenem resistance in three of theK. pneumoniaeisolates was loss of theKlebsiellaporin channel protein OmpK36 as shown by PCR analysis. The remaining twoK. pneumoniaeisolates exhibited increased expression of a tripartite AcrAB–TolC efflux pump as demonstrated by SDS-PAGE and mass spectrometry analysis of bacterial outer-membrane extracts, which, in addition to other unknown mechanisms, may contribute towards increasing the carbapenem MIC values further. Carbapenem-non-susceptible ESBL isolates may pose a new problem in the future due to possible outbreak situations and limited antibiotic treatment options. Therefore, a systematic exploration of intestinal colonization with ESBL isolates should be reconsidered, at least for haemato-oncological departments from where four of the five carbapenem-non-susceptible ESBL isolates originated.

Proteomics facilities accumulate large amounts of proteomics data that are archived for documentation purposes. Since proteomics search engines, e.g. Mascot or Sequest, are used for peptide sequencing resulting in peptide hits that are ranked by a score, we apply ranking algorithms to combine archived search results into predictive models. In this way peptide sequences can be identified that frequently achieve high scores. Using our approach they can be predicted directly from their molecular structure and then be used to support protein identification or perform experiments that require reliable peptide identification. We prepared all peptide sequences and Mascot scores from a four year period of proteomics experiments on Homo sapiens of the Proteome Center Tuebingen for training. To encode the peptides MacroModel and DragonX were used for molecular descriptor computation. All features were ranked by ranking-specific feature selection using the Greedy Search Algorithm to significantly improve the performance of RankNet and FRank. Model evaluation on hold-out test data resulted in a Mean Average Precision up to 0.59 and a Normalized Discounted Cumulative Gain up to 0.81. Therefore we demonstrate that ranking algorithms can be used for the analysis of long term proteomics data to identify frequently top scoring peptides.

Cyperaceae (sedges) are an important component of many ecosystems. To understand better their regeneration, we examined seed ecology, including dispersal, seed characteristics, and germination behavior that relate to seed bank development and persistence. We also evaluated sedge seed banks from 104 studies, representing a wide array of habitats. Sedge seed bank development and persistence were associated with germination and dormancy traits, namely: dormancy level, seasonal dormancy patterns, and requirement for light, alternating temperatures, and aerobic conditions. Interplay of traits appears to have resulted in low-risk germination strategies adapted to exploit infrequent occurrence of gaps and facilitate formation of persistent seed banks. A variety of dispersal modes and morphological adaptations occurred, but many species had no apparent specialized structures. The main dispersal vectors were water and then animals. About 216 species, in 21 genera, were recorded in the seed bank survey. High densities (>50,000 m−2) occurred occasionally in wet habitats, but generally values were low ( 1 year). Maximum longevity ranged between 10 and 295 years, but for certain species viability was lost in 1 m. Seed production, low in rhizomatous species, ranged between 0 and 345,000 seeds m−2 year−1. Amphicarpy or pseudo-viviparous plantlets occurred in limited numbers of species. The relation between seed production, seed rain, and seed bank is largely obscure and awaits further investigation. For successful restoration and species conservation projects, seed banks (or a source of seeds) are necessary, combined with suitable germination and establishment conditions. Future seed bank studies are considered.

The effects of stratification temperatures and burial in soil on dormancy levels of Carex pendula L. and C. remota L., two spring-germinating perennials occurring in moist forests, were investigated. Seeds buried for 34 months outdoors, and seeds stratified in the laboratory at temperatures between 3 and 18 °C for periods between 2 and 28 weeks, were tested over a range of temperatures. Seeds of the two species responded similarly to stratification treatments, except for an absolute light requirement in C. pendula. Primary dormancy was alleviated at all stratification temperatures, but low temperatures were more effective than higher ones . (≥ 12 °C). Dormancy induction in non-dormant seeds kept at 5 °C occurred when seeds were subsequently exposed to 18 °C. Dormancy was not induced by a transfer to lower temperatures. Buried seeds of both species exhibited seasonal dormancy cycles with high germination from autumn to spring and low germination during summer. Temperatures at which the processes of dormancy relief and of dormancy induction occurred, overlapped to a high degree. Whether, and when, dormancy changes occurred depended on test conditions. The lower temperature limit for germination (> 10%) was 9 °C in C. remota and 15 °C in C. pendula. Germination ceased abruptly above 36 °C. Germination requirements and dormancy patterns suggest regeneration from seed in late spring and summer at disturbed, open sites (forest gaps) and the capability to form long, persistent seed banks in both species.

Variation in dormancy of the wetland sedge, Carex elongata L., was tested using seeds from three wild populations and the garden-grown progeny of one population. Germination experiments, comprising four combinations of temperature and light, were conducted either with fresh-matured or cold-stratified seeds, to assess the relative contribution of populations and mother plants to the total variation. Between-year variation was tested at the population level and, partly, at the individual level, using seeds collected in two consecutive years. Among-population variation accounted for 72%, and among-individual variation for 23%, of the total variance in the first experiment. Significant differences were apparent between one wild population and its garden-grown descendants. Differences in germinability among populations were maintained in the two consecutive years, but a proportion of the variance was due to the contribution of the maternal environment. Weak evidence for genetic control at the individual level was shown by a correlation across years in one population. However, the lack of a main effect at the individual level in the first experiment makes it difficult to assess the relative contribution of the mother plants to the total variation. Our results imply that germination patterns of C. elongata have a genetic basis, but are markedly modified by environmental conditions.

Dormancy patterns and germination responses to incremental stratification were investigated in Verbena officinalis L. (Verbenaceae), a widely-distributed ruderal, but considered as an originally mediterranean plant. In an initial experiment, samples of seeds buried in the field were exhumed at monthly intervals over a period of 38 months and tested for germination in light and darkness at 25/15 °C and 15/5 °C. Seeds were strongly dormant when fresh and mature and came out of dormancy during winter. Seeds entered conditional dormancy in spring, while main dormancy relief occurred in winter. There was no seed mortality, and no germination occurred in the soil during burial. The results imply, that V. officinalis germinates preferably in late spring and has the potential to accumulate a persistent seed bank. The effects of stratification temperature and duration on dormancy were investigated in a second experiment. Dry-stored seeds were stratified wet at a range of temperatures from 3–18 °C in darkness for periods of up to 28 weeks, and tested over a range of constant temperatures (3–25 °C) and at 15/5 °C in light, and at 25 °C and 15/5 °C in the dark. Seeds came out of primary dormancy when kept at temperatures between 3–12 °C, while higher temperatures were ineffective in breaking dormancy. There was no induction of secondary dormancy during the stratification period of 28 weeks. We conclude that a gradual increase of the ambient temperatures and/or an increase in amplitude size is required for dormancy induction. Weakly dormant seeds required either high constant mean (>15 °C), or fluctuating temperatures for germination. Only a small fraction of the seeds acquired the ability to germinate in darkness with incremental stratification. There is no indication of germination and dormancy traits that can be interpreted as relict adaptations to mediterranean conditions. Der zeitliche Verlauf der Samendormanz und die Veranderung des Keimungsverhaltens von Verbena officinalis L. (Verbenaceae) unter verschiedenen Stratifikationsbedingungen wurden untersucht. Verbena officinalis ist eine weit verbreitete Art ruderaler Standorte, die wahrscheinlich aus dem mediterranen Raum stammt. In einem ersten Experiment wurde die Keimung von Samen, die in einem Versuchsgarten vergraben wurden, in monatlichen Abstanden uber einem Zeitraum von 38 Monaten, bei 25/15 °C und 15/5 °C in Licht und Dunkelheit getestet. Frisch gereifte Samen wiesen eine starke Dormanz auf, die sie wahrend des Winters verloren. Vom Fruhling bis zum Sommer wurde eine sekundare Dormanz induziert, deren Niveau starken Schwankungen unterlag und die erst im Winter wieder abgebaut wurde. Bis zum Ende des Versuchs konnte weder Samenmortalitat, noch eine Keimung im Boden festgestellt werden. Die Ergebnisse zeigen, dass V. officinalis bevorzugt im spaten Fruhjahr keimt und die Fahigkeit besitzt, eine dauerhafte Samenbank aufzubauen. Die Auswirkungen von Dauer und Temperatur einer Stratifikation auf die Samendormanz wurden in einem zweiten Experiment untersucht. Die Keimung trocken gelagerter und anschliesend bei Temperaturen zwischen 3 °C und 18 °C bis zu 28 Wochen feucht stratifizierter Samen wurde getestet. Hierzu wurden die Samen bei mehreren konstanten Temperaturen zwischen 3 °C und 25 °C, sowie bei einer Wechseltemperatur von 15/5 °C im Licht und zusatzlich bei 25 °C und 15/5 °C in Dunkelheit inkubiert. Die Samen verloren ihre Dormanz, wenn sie in einem Tempera-turbereich von 3 °C bis 12 °C stratifiziert wurden, wohingegen hohere Temperaturen keinen Einfluss hatten. Wahrend des gesamten Stratifikationszeitraums war eine Induktion sekundarer Dormanz nicht zu beobachten. Wir schliesen daraus, dass ein Temperaturanstieg und/oder ein Anstieg der Hohe der Tagestemperaturamplitude fur eine Induktion sekundarer Dormanz notwendig ist. Nicht dormante Samen benotigten eine hohe Durchschnittstemperatur (>15 °C) oder fluktuierende Temperaturen zur Keimung. Lediglich ein geringer Teil der Samen erlangte mit zunehmender Stratifikation die Fahigkeit in Dunkelheit zu keimen. Keine der Dormanz- oder Keimungseigenschaften von V. officinalis kann als reliktische Anpassung an mediterrane Bedingungen interpretiert werden.

Recently, we reported that mutation A1529D in the domain (D) IV P-loop of the rat skeletal muscle Na(+) channel mu(1) (DIV-A1529D) enhanced entry to an inactivated state from which the channels recovered with an abnormally slow time constant on the order of approximately 100 s. Transition to this "ultra-slow" inactivated state (USI) was substantially reduced by binding to the outer pore of a mutant mu-conotoxin GIIIA. This indicated that USI reflected a structural rearrangement of the outer channel vestibule and that binding to the pore of a peptide could stabilize the pore structure (Hilber, K., Sandtner, W., Kudlacek, O., Glaaser, I. W., Weisz, E., Kyle, J. W., French, R. J., Fozzard, H. A., Dudley, S. C., and Todt, H. (2001) J. Biol. Chem. 276, 27831-27839). Here, we tested the hypothesis that occlusion of the inner vestibule of the Na(+) channel by the fast inactivation gate inhibits ultra-slow inactivation. Stabilization of the fast inactivated state (FI) by coexpression of the rat brain beta(1) subunit in Xenopus oocytes significantly prolonged the time course of entry to the USI. A reduction in USI was also observed when the FI was stabilized in the absence of the beta(1) subunit, suggesting a causal relation between the occurrence of the FI and inhibition of USI. This finding was further confirmed in experiments where the FI was destabilized by introducing the mutations I1303Q/F1304Q/M1305Q. In DIV-A1529D + I1303Q/F1304Q/M1305Q channels, occurrence of USI was enhanced at strongly depolarized potentials and could not be prevented by coexpression of the beta(1) subunit. These results strongly suggest that FI inhibits USI in DIV-A1529D channels. Binding to the inner pore of the fast inactivation gate may stabilize the channel structure and thereby prevent USI. Some of the data have been published previously in abstract form (Hilber, K., Sandtner, W., Kudlacek, O., Singer, E., and Todt, H. (2002) Soc. Neurosci. Abstr. 27, program number 46.12).

Summary Germination ecology of Parthenium hysterophorus , recently introduced to Ethiopia, was studied in a series of experiments. Viability of the seeds was greater than 50% after 26 months of burial in the soil indicating the potential build-up of a substantial persistent soil seed bank. A short period of dry storage was sufficient to overcome a light requirement for germination in a minor fraction of the seeds. Likewise, seeds exhumed from burial showed an increase in germination ability in darkness over time, with a weak tendency for seasonal cyclicity in dormancy level at one of two sites. Germination occurred at the mean minimum (10 °C) and maximum (25 °C) temperatures of the collection sites, as well as over a wide range of fluctuating (12/2 °C-35/25°C) temperatures in light. No germination of P. hysterophorus seeds occurred at osmotic potentials < -0.52 MPa (at 27 °C), the species being less tolerant to moisture stress than sorghum grains. Most seedlings emerged from shallowly buried (< 0.5 cm) seeds and none from more than 5 cm depth. Naturally dispersed seeds required about 60 days, at a hot lowland site, to start emergence despite the presence of adequate rainfall, and higher number of seedlings emerged in undisturbed plots than in hand hoed plots. These experiments and field observations suggest that there are no obvious climatic conditions that may limit the germination of Parthenium hysterophorus in Ethiopia, but a high moisture requirement of the seeds for germination could be the major factor limiting germination during the dry season.

The germination ecology of four annual Bromus species, which differ in weediness on arable land in southern Sweden, was investigated. The most problematic species is Bromus sterilis, while Bromus hordeaceus frequently occurs on arable land. In contrast, Bromus arvensis is a rare weed, and Bromus tectorum is found infrequently in fields despite being a widespread ruderal species. Five experiments were conducted to identify germination characteristics that could explain differences in habitat and abundance: (i) intraspecific variation in dormancy level; (ii) germination response to different light conditions; (iii) light and temperature interactions at germination; (iv) timing of seedling emergence; and (v) seed persistence in soil. Bromus sterilis and B. tectorum behaved similarly in all tests. For both these species, there were large differences in dormancy level among populations and strong inhibition of germination by light. In addition, emergence from seeds sown on the soil surface was both delayed and reduced compared with buried seeds. In contrast, B. hordeaceus and B. arvensis showed generally weak dormancy, and germination was only slightly inhibited by light. It was concluded that germination characteristics alone do not explain the differences in weediness between these four species.

We conducted experiments on seed germination, seedling survival and seedling growth of four Eucalyptus species to identify factors that might explain why they are restricted to the two major soil types in southwestern Australia, deep sands ( E. macrocarpa, E. tetragona ) and lateritic loam (E. loxophleba, E. wandoo). At high temperatures (28 °C), germination in darkness was lower for the two ‘loam species’ than for the ‘sand species’, while there were no differences in light or at low temperatures (10 °C). Germination commenced earlier, and was faster in the sand species than in the loam species, but was almost inhibited in all species by –1.0 MPa. E. tetragona proved the most drought-tolerant in terms of germination level and seedling survival. Seedlings of the sand species had much longer roots two weeks after germination in the absence of water stress, and the roots of more seedlings continued to elongate under moderate water stress (–1.0 MPa), than the two loam species. Roots were longer in all species, except E. macrocarpa, at –0.5 MPa than at –0.1 MPa, despite seedlings having a smaller mass and hypocotyl length. As water availability declined, there was a tendency for the sand species to survive longer on sand than on loam while soil type had no effect on the loam species. Pattern and duration of seedling survival of the loam species was similar to that of the sand species despite their smaller seeds. We conclude that seedlings from the large-seeded sand species are able to penetrate the soil profile faster and deeper, but that they are not less prone to drying soils than seedlings from the small-seeded loam species. Instead, seed size and germination speed are important prerequisites to cope successfully with unstable soil surfaces and to exploit the rapidly descending water in deep sands. © 2002 Editions scientifiques et medicales Elsevier SAS. All rights reserved.

Summary The timing of seed germination is thought to play an important role for species abundance and community composition in alpine habitats. Seed dormancy and germination responses to temperature and light of two widespread alpine sedges were investigated in order to gain insight into mechanisms regulating germination in the field. Seeds of Carex ferruginea germinated at high temperatures when freshly matured and were thus conditionally dormant. Germination percentages increased markedly due to dry storage and cold stratification, accompanied by a decrease of the minimum temperature for germination. Freshly-matured seeds of C. frigida required cold stratification to release strict dormancy, but germination was restricted to high temperatures (> 15 °C). The existence of a carry-over mechanism, preventing the major fraction of current-year seeds to germinate even under optimum conditions in the next growing season was shown for this species. Seeds of both species showed very little germination in darkness and attained a germination peak in light after three month of stratification. The period of cold-stratification required to break dormancy was not related to winter duration as has been found in several species from high altitudes in America. Seeds buried outdoors underwent seasonal changes in dormancy, a trait which was hitherto not known in alpine plant species. Primary seed dormancy, a requirement for relatively high germination temperatures in stratified seeds and the induction of secondary dormancy in early summer by increasing temperatures restrict the ‘germination window’ to a short period after snowmelt in both species. Such a cautious type of seed regeneration may increase the chance of a seedling becoming established at the expense of the number of germinating seeds. This strategy is based on a light requirement for germination, enabling both species to built-up a large seed reservoir in the soil. Die Haufigkeit von Arten und die Zusammensetzung der Vegetation in alpinen Lebensraumen wird wahrscheinlich durch den richtigen Zeitpunkt fur die Keimung entscheidend mitbestimmt. Samendormanz und Keimungverhalten unter verschiedenen Licht- und Temperaturbedingungen wurden fur zwei weit verbreitete alpine Seggen untersucht, um Mechanismen zu identifizieren, die unter naturlichen Bedingungen die Keimung regulieren. Frisch gereifte Samen von Carex ferruginea keimten bei hohen Temperaturen und sind daher konditional dormant. Der Anteil gekeimter Samen wurde durch trockene Lagerung und kalte Stratifikation deutlich erhoht, bei gleichzeitiger Erniedrigung der Minimaltemperatur fur die Keimung. Frische gereifte Samen von C. frigida benotigten fur die teilweise Aufhebung einer absoluten Dormanz eine kalte Stratifikation, aber auch dann erfolgte eine Keimung nur bei recht hohen Temperaturen (> 15 °C). Fur diese Art wurde ein “carry-over”-Mechanismus nachgewiesen, der auch unter optimalen Bedingungen eine Keimung des groseren Teils der diesjahrigen Samen im folgenden Fruhjahr verhinderte. Samen beider Arten keimten kaum in Dunkelheit und erreichten die hochsten Werte nach einer dreimonatigen Stratifikationsperiode. Im Gegensatz zu einigen Arten hoherer Lagen in Amerika war die Dauer dieser Periode nicht mit der Dauer des Winters korreliert. Im Freiland vergrabene Samen zeigten saisonale nderungen des Dormanz-Niveaus, was bisher von alpinen Arten nicht bekannt war. Primare Samendormanz, relativ hohe Keimungstemperaturen auch nach Stratifikation und die Induktion einer sekundaren Dormanz im Fruhsommer durch steigende Temperaturen schranken das “Keimungsfenster” fur beide Arten auf eine kurze Periode nach der Schneeschmelze ein. Dieser durch zahlreiche Einschrankungen potentieller Keimungsmoglichkeiten gekennzeichnete Typ der “vorsichtigen” generativen Regeneration erhoht die Chance eines Keimlings sich zu etablieren, allerdings auf Kosten der Zahl auflaufender Samen. Ein wichtiger Bestandteil dieser Strategie ist die Notwendigkeit von Licht fur die Keimung, da sie die Voraussetzung fur den Aufbau eines umfangreichen Samenreservoirs im Boden bildet.

The genus Carex , with its wide distribution and large number of species yet with a rather uniform life history, is a very convenient group for comparative studies of germination ecology at the generic level. The combination of a strict or conditional primary dormancy, a light requirement for germination, low germination at constant temperatures, a positive response to diurnal temperature fluctuations and an induction of secondary dormancy in late spring by increasing environmental temperatures are attributes that were found to be characteristics shared by almost all the Carex species investigated, though there was variation between species in the degree to which these characters were expressed. In almost all species, dormancy was broken by stratification at low temperatures, though few species gained the ability to germinate at temperatures 0.9 mg), probably due to a thicker seed coat and hence a higher resistance to germination. Differences in primary dormancy between sedges of various habitats could not be established. However, there was a tendency for temperature limits to be low in forest sedges. Many species of wetlands and open sites showed a greater capability to respond to fluctuating temperatures than species of dry sites. These dormancy and germination traits not only enable the accumulation of seeds in the soil, but also constitute seasonal seed regeneration strategies that rely on the high longevity of seeds and the formation of persistent seed banks. Temperate Carices are mainly adapted to exploit the temporally and spatially infrequent occurrence of canopy gaps that become available only in late spring or early summer, whereas the colonization of gaps at the beginning of the vegetation period is largely prevented by a high temperature requirement for germination. Many of the dormancy and germination characteristics of Carices are important in Cyperaceae generally. A greater diversity of germination responses, however, can be found in the related families, Juncaceae and Poaceae. Our present knowledge is not sufficient to determine unequivocally whether a phylogenetic component contributes significantly to the germination behaviour of the genus Carex , but certain tendencies are clearly indicated.

Summary Effects of diurnal temperature fluctuations on the germination of 34 temperate Carex -species were investigated. Experiments were conducted on recently matured seeds at 22°C mean temperature with fluctuation amplitudes of 0° – 16°C, and at 22/10°C (15°C mean temperature) in light and darkness before and after a cold-wet stratification. At 22°C mean temperature, seed germination increased in almost all investigated species with increasing temperature amplitudes, in both light and darkness. The average germination percentage across all species was 29.4% in light and 5.1 % in darkness. The averaged amplitude required to reach 50% of maximum germination was 9.8°C. Species with little sensitivity to temperature fluctuation in light showed a clear sensitivity in darkness. The germination percentage was 4.0% for species with seed weights >0.9 mg and 23% for species with seed weights Carex species, thus suggesting that their germination behaviour was determined not only by habitat conditions.

The germination responses of 32 temperate Carex species were tested in light and darkness at five constant temperatures and under one fluctuating temperature regime, before and after cold-wet stratification. Using a linear logistic regression model, the probability of germination tested across all species was found to be significantly higher after stratification, in light and at the fluctuating temperature. In addition, the probability increased with temperature. Stratification increased germination in 28 species and had very little or no effect on four species. There was almost no germination in darkness prior to stratification, and the germination in light was considerably higher in all but two species compared with that in darkness. Thus, it can be concluded that the Carex species tested have broadly similar germination response patterns. The fact that Carices can be released from high levels of primary dormancy by low-temperature stratification implies that they are spring germinators. A light requirement after stratification in the major fraction of seeds and the capability of almost all investigated sedges to respond to fluctuating temperatures make it likely that persistent seed banks are formed. Additionally, sedges generally seem to have a high temperature requirement for germination which prevents them from emerging at the very beginning of the growing season. Regeneration by seed is probably largely restricted to gaps resulting from late spring disturbances where buried seeds have an opportunity to germinate and grow. Differences in germination were apparent between species occupying different habitats. Overall germination was significantly higher in wetland species than in dry-site species, probably owing to the greater capability of wetland species to respond to fluctuating temperatures. Differences in germination between forest and open-site species can be attributed to the higher capability of forest sedges to respond to low temperatures and temperature fluctuations. The influence of seed weight on germination was not significant in the 18 species adapted to wet, open habitats. There was, however, a tendency for the germination percentages to be low for large-seeded Carices. The interpretation of habitat differences is difficult due to a positive correlation between seed weight and dry habitats.

Seeds (nutlets) of four temperate-zone perennialCarex species from various habitats and with different growth forms were investigated to identify seasonal germination patterns. In the first experiment, freshly matured seeds were sown in summer 1994 on the soil surface and at a depth of 1 cm at a sunexposed site and under a leaf canopy in an experimental garden. In the second experiment, seeds were exhumed after various periods of burial (7-cm depth) for up to 30 months and tested for germination in both light and darkness at 15°, 25°, and 22/10°C. In the first experiment, freshly-matured seeds of the four sedges did not germinate during summer or autumn 1994. Almost all surface-sown seeds of the four species germinated from late spring to summer in 1995 at the sun-exposed site. Most buried seeds of three species germinated in the soil, but germinants died prior to emergence. InCarex flacca, however, about 50% of the buried seeds germinated and emerged until 1997, and the ungerminated seeds remained viable. At the shaded site, seeds ofC. acutiformis. andC. flacca did not germinate, whereas a small percentage of the buried and surface-sown seeds ofC. arenaria andC. extensa emerged in the second year. Seeds ofC. acutiformis andC. flacca were dormant, and those ofC. arenaria andC. extensa were conditionally dormant at the beginning of the second experiment. All four species had annual dormancy cycles at 22/10°C in light and in darkness and at 25° and 15° in light. Seeds came out of dormancy in late autumn or winter and re-entered dormancy or conditional dormancy in late spring or early summer. Very few seeds of any of the four species germinated at constant temperatures in darkness. No seeds germinated during burial in soil at a depth of 7 cm. These field germination patterns indicate that the four sedges have the potential to form a persistent seed bank but that losses due to germination in the seed bank are dependent on temperature amplitudes, mean temperatures, and red: far red ratios under a leaf canopy.

The effects of dry after-ripening and burial in the soil on seed germination of six temperate wetland Carex spp. were investigated. Freshly matured seeds, seeds stored dry for 4 or 8 weeks, and seeds buried at 7-cm depth in a small woodlot, and exhumed at approximately bimonthly intervals over a 2-year period, were tested under a fluctuating (22°/10°C) and a constant temperature regime (15°C) in light and darkness, respectively. Fresh and dry-stored seeds of all species were conditionally dormant at 22°/10° in the light, dormant at 15° in light and darkness and at 22°/10°C in darkness. Dry after-ripening increased significantly germination percentages in three species. Buried seeds of all six species exhibited annual dormancy cycles at 22°/10°C in darkness and 15°C in the light, whereas, no germination occurred at 15°C in darkness. Seeds came out of dormancy in late autumn or winter and entered dormancy in late spring or early summer. Germinability did not show any cyclicity at 22°/10°C in the light in four species and showed weak cyclicity in two species. Seed mortality was low, and no germination occurred during burial. This implies that the six species can accumulate a persistent seed bank.

Long-term application of the phorbol ester phorbol 12,13-dibutyrate (PDBu) inhibits the proliferation of human venous endothelial cells. The cyclin-dependent kinase inhibitor p21 cip1 is a potential candidate mediating the PDBu-induced delayed entry of the cells into S-phase (by ∼10 h when compared with cells stimulated with basic fibroblast growth factor (bFGF)). Levels of p21 cip1 (protein and mRNA) rapidly rise (within ∼2 h) in endothelial cells treated with the active isomer β-PDBu, but not with α-PDBu; this effect is blocked by the mitogen-activated protein kinase kinase-1 (Mek1) inhibitor PD098059 and by the protein kinase C (PKC) antagonists GF109203X and rottlerin (selective for PKC-δ), but not Go 6976 (selective for Ca2+-dependent PKC isoforms). Rapamycin blocks the PDBu-induced accumulation of p21 cip1 (but not of the cognate mRNA), indicating an action of PKC on p21 cip1 mRNA translation. If endothelial cells are recruited into the cell cycle by bFGF, p21 cip1 mRNA and protein levels rise initially (within 2 h) and decline subsequently such that p21 cip1 drops to a minimum prior to the initiation of DNA synthesis (i.e. after ∼12 h). In bFGF-stimulated cells, changes in p21 cip1 mRNA and protein are strictly linked. In contrast, the levels of p21 cip1 mRNA decline substantially (>10 h) before the protein decreases in PDBu-stimulated cells. Thus, PKC (presumably PKC-δ) regulates the amounts of p21 cip1 in endothelial cells at the level of mRNA accumulation and translation, leading to a rapid and robust induction; following persistent PKC activation, p21 cip1 remains elevated despite reduced mRNA levels, indicating an enhanced stability of the protein. The bFGF-mediated increase in p21 cip1 is blocked by the Mek1 inhibitor, but not by GF109203X; hence, in endothelial cells, induction of p21 cip1 by PKC- and growth factor-dependent signaling is achieved by distinct pathways that converge and require activation of the mitogen-activated protein kinase cascade. The β-PDBu-induced delayed S-phase entry and drop in p21 cip1 are reversed if GF109203X is added 4 h after β-PDBu to prevent persistent PKC activation. These observations indicate a cause and effect relation between sustained p21 cip1 elevations and the delay in S-phase entry induced by β-PDBu.

Based on previous studies showing an increase in circulating soluble intercellular adhesion molecule-1 (sICAM-1) after exercise, we hypothesized that exercise may also increase serum levels of the vascular cell adhesion molecule-1 (sVCAM-1) and sE-selection. In a prospective controlled clinical trial, serum levels of sE-selectin, sICAM-1 and sVAM-1 were measured before and after two different exercise protocols in healthy untrained men. Lactate levels increased up to 12.7 mmol/L (95% confidence interval: 10.1-15.9) and 3.6 mmol/L (CI: 2.4-4.7) after ergometry and after an one hour endurance exercise at 60% of the maximal work intensity, respectively (p = 0.028 vs baseline and controls). The maximal increase in lymphocyte counts of 106% (CI: 63-146), which was only of short duration, was higher immediately after ergometry as compared to that observed after endurance exercise (p = 0.028). However, the maximal increase in neutrophil counts of 178% (CI: 120-298) which was seen at 2 hours after endurance exercise was higher than that seen after ergometry (p = 0.028). In contrast, only small changes of circulating adhesion molecules were seen immediately after ergometry: sICAM-1 increased by 11% (CI: 4-25; p = 0.028), and similar tendencies were also observed for sVCAM-1 and sE-selectin. No other consistent and time-dependent changes of circulating adhesion molecules were observed and all differences and changes were < or = 11%. In sum our study provides evidence that recreational sporting activities in untrained healthy subjects at normal altitude have little influence on serum levels of the circulating vascular adhesion molecules sE-selectin, sVCAM-1 or sICAM-1.

The seed germination behaviour of six cold-temperate, cespitose Carex species occurring either in wet forests or wet, open habitats was investigated under different light and temperature conditions. Germination tests were conducted in the laboratory with cold and wet stratified seeds in light and darkness, under four constant-temperature regimes and one fluctuating regime. Other germination tests were carried out in an experimental garden where freshly matured seeds sown on the soil surface were exposed to conditions typical for a sun-exposed site and a shaded (forest) site for 2 years. In the garden experiments, seeds at the sun-exposed site germinated soon after sowing in three species, whereas late-shedding species or species exhibiting primary dormancy germinated the following spring. Under the dense leaf canopy at the forest site, germination was inhibited completely during the first season in all species. Wet-forest species (Carex elongata, Carex remota) germinated the following spring before the leaf canopy closed, whereas the sedges adapted to open habitats (Carex canescens, Carex cespitosa, Carex pseudocyperus, Carex paniculata) failed to germinate, or only a low percentage germinated. Following transfer of ungerminated seeds from the shaded site to the sun-exposed site in the summer of the second year of the investigation, almost all of the hitherto ungerminated seeds germinated within 10 days. Results of laboratory experiments supported the findings in the garden experiments. At low mean temperatures (7 and 10 °C) in light, sedges adapted to open habitats did not germinate at all or showed a low percentage of germination, whereas forest sedges showed good germination. A high diurnal temperature amplitude and (or) a high constant temperature was needed to trigger the germination of a fraction of the seeds in dark treatments. It is suggested that the forest sedges are adapted to using a brief temporal regeneration niche during mid-spring, when mean temperatures are close to 10 °C and the leaf canopy has yet to close in central European, wet deciduous forests. In contrast, sedges adapted to open habitats probably fail to germinate under forest conditions because of their higher temperature requirements. Key words: Carex, germination, light, temperature, dormancy.

Achenes (seeds) of the perennial shrub Launaea arborescens (Asteraceae) germinated under a wide range of environmental conditions. None of the seeds were dormant, nor was there any evidence that dormancy could be induced. Apparently, this semi-desert species has no means of preventing immediate germination. Achenes are produced and dispersed throughout the year, and we suggest that the timing of germination is regulated by the duration and degree of wetting and the presence of moderate soil temperatures. This germination behaviour suggests that there is no mechanism by which the germination of seeds formed one year can be delayed until subsequent years. By contrast, most desert plants accumulate persistent seed banks. The germination strategy of L. arborescens must be considered opportunistic, and we suggest that the survival of populations is ensured by other life history traits like continuous iteroparity and effective dispersal by wind.

Adenosine exerts a mitogenic effect on human endothelial cells via stimulation of the A2A-adenosine receptor. This effect can also be elicited by the beta2-adrenergic receptor but is not mimicked by elevation of intracellular cAMP levels. In the present work, we report that stimulation of the A2A-adenosine receptor and of the beta2-adrenergic receptor activates mitogen-activated protein kinase (MAP kinase) in human endothelial cells based on the following criteria: adenosine analogues and beta-adrenergic agonists cause an (i) increase in tyrosine phosphorylation of the p42 isoform and to a lesser extent of the p44 isoform of MAP kinase and (ii) stimulate the phosphorylation of myelin basic protein by MAP kinase; (iii) this is accompanied by a redistribution of the enzyme to the perinuclear region. Pretreatment of the cells with cholera toxin (to down-regulate Gsalpha) abolishes activation of MAP kinase by isoproterenol but not that induced by adenosine analogues. In addition, MAP kinase stimulation via the A2A-adenosine receptor is neither impaired following pretreatment of the cells with pertussis toxin (to block Gi-dependent pathways) nor affected by GF109203X (1 microM; to inhibit typical protein kinase C isoforms) nor by a monoclonal antibody, which blocks epidermal growth factor-dependent signaling. In contrast, MAP kinase activation is blocked by PD 098059, an inhibitor of MAP kinase kinase 1 (MEK1) activation, which also blunts the A2A-adenosine receptor-mediated increase in [3H]thymidine incorporation. Activation of the A2A-adenosine receptor is associated with increased levels of GTP-bound p21(ras). Thus, our experiments define stimulation of MAP kinase as the candidate cellular target mediating the mitogenic action of the A2A-adenosine receptor on primary human endothelial cells; the signaling pathway operates via p21(ras) and MEK1 but is independent of Gi, Gs, and the typical protein kinase C isoforms. This implies an additional G protein which links this prototypical Gs-coupled receptor to the MAP kinase cascade.

Summary The aquatic vegetation of 44 calcareous streams of a moraine (Oberschwaben) and a Karst landscape (Schwabisch Alb) in Southwestern Germany, encompassing approximately 10 000 km2, was mapped from 1987 to 1990. A DCA-ordination revealed floristic differences between the “Oberschwaben” streams and the “Schwabisch Alb” streams. The main differences found were as follows: Groenlandia densa and Hippuris vulgaris occurred in many of the upper reaches and sources of Karst streams but were almost completely absent from the “Oberschwaben” streams. Elodea canadensis, Zannichellia palustris and Potamogeton pectinatus were abundant in most of the moraine streams but were uncommon in the Karst streams. The Danube was characterized by the dominance of Ranunculus fluitans and the sparse occurrence of rhitral species. A comparison of the present vegetation patterns with patterns recorded prior to the 1960's revealed a considerable change on a landscape scale. Species richness decreased in most of the streams and s...

During recent years a number of severe clinical syndromes, collectively termed laminopathies, turned out to be caused by various, distinct mutations in the human LMNA gene. Arising from this, remarkable progress has been made to unravel the molecular pathophysiology underlying these disorders. A great benefit in this context was the generation of an A-type lamin deficient mouse line (Lmna\(^{−/−}\)) by Sullivan and others,1 which has become one of the most frequently used models in the field and provided profound insights to many different aspects of A-type lamin function. Here, we report the unexpected finding that these mice express a truncated Lmna gene product on both transcriptional and protein level. Combining different approaches including mass spectrometry, we precisely define this product as a C-terminally truncated lamin A mutant that lacks domains important for protein interactions and post-translational processing. Based on our findings we discuss implications for the interpretation of previous studies using Lmna\(^{−/−}\) mice and the concept of human laminopathies.

Prolongation of action potential duration during treatment with agents that possess class I antiarrhythmic activity may result in a clinically relevant increase in Na+ channel block. In order to test this hypothesis in vivo, the effect of QT prolongation on intraventricular conduction was assessed during administration of mexiletine. Epicardial His bundle recordings were made in anesthetized guinea pigs. After abolition of spontaneous sinus node activity by application of high-frequency current to the sinus node area, the hearts were paced via the left atrium. Administration of the class III antiarrhythmic agent dofetilide (10 micrograms/kg i.v.; n = 6) significantly prolonged QT intervals without a significant effect on HV intervals. Infusion of mexiletine (bolus 2 mg/kg + 0.18 mg/kg per min i.v.; n = 6) produced significant increases in HV intervals at cycle lengths of 200 and 300 ms. Subsequent addition of dofetilide (20 micrograms/kg i.v.) to mexiletine induced similar increases in QT intervals as single treatment with 10 micrograms/kg dofetilide and significantly enhanced the rate-dependent conduction slowing. Upon abruptly decreasing the pacing cycle length from 500 ms to 300 ms, conduction slowing developed with a rate constant of 1.0 +/- 0.2 beat-1 after mexiletine and with a rate constant of 1.1 +/- 0.2 beat-1 after subsequent addition of dofetilide (P = n.s.). After rapid stimulation at a cycle length of 250 ms the conduction slowing produced by mexiletine recovered with a time constant of 174 +/- 24 ms. No further change of this recovery time constant was observed after subsequent addition of dofetilide to mexiletine (160 +/- 19 ms, P = n.s.). Thus action potential duration, as reflected by the QT interval, is an important modulator of the magnitude Na+ channel block in vivo. The kinetic parameters of Na+ channel block produced by mexiletine, however, remain unchanged by prolongation of action potential duration after addition of dofetilide.

Sporadic inclusion body myositis (sIBM) contains non‐necrotic myofibers that are surrounded and/or invaded by inflammatory cells. In this study we aimed to identify selective molecules that are present at this site. Myofibers of four biopsies of sIBM that were surrounded and/or invaded by inflammatory cells were microdissected, pooled and profiled by proteomic studies using mass spectrometry. Normal skeletal muscle tissue served as control. Based on the table of proteins that were detected in sIBM only, we selected nine extracellular matrix molecules and validated the results performing immunofluorescence. Seven out of nine proteins that were detected in sIBM by mass spectrometry showed different immunohistochemical results in myositis and normal controls. Of these, the small leucine‐rich repeat proteins proline arginine‐rich end leucine‐rich repeat protein (PRELP) and biglycan were deposited precisely at myofibers surrounded and/or invaded by inflammatory cells both in sIBM and polymyositis. The basement membrane (BM) molecules merosin, perlecan, nidogen‐2 and collagen IV were variably destroyed or increased at these sites. P component, which ensheathed all myofibers in normal controls, was absent from invaded myofibers. Similar to BM remodeling, the specific deposition of PRELP and biglycan may represent a mechanism to defend against immune attack. Loss of P component may affect the anchorage of the myofiber in the endomysium.

We show an iterative algorithm that allows to obtain accurate Compton profiles J(q) from Compton scattering spectra I2 (ω2), if the excitation radiation is not strictly monochromatic. It requires knowledge of the spectral distribution of the primary radiation I1(ω1), validity of the impulse approximation and dominance of a monochromatic part in I1(ω1) over the polychromatic rest. Conversely, the primary spectrum is often experimentally not directly accessible. In such a situation it is possible to evaluate the primary spectrum I1(ω1) from the spectrum of scattered photons, I2(ω2), with a similar iterative algorithm. We use a scattering target of high atomic number in order to ensure that the elastically scattered photons dominate the inelastically scattered ones. From the scattered spectrum we get a model for the Compton profile that allows us to separate the inelastic part of the scattered spectrum from the elastic part, which, in turn, is proportional to the spectral distribution of the primary radiation.

Bacillus subtilis BY-kinase PtkA was previously shown to phosphorylate, and thereby regulate the activity of two classes of protein substrates: UDP-glucose dehydrogenases and single-stranded DNA-binding proteins. Our recent phosphoproteome study identified nine new tyrosine-phosphorylated proteins in B. subtilis. We found that the majority of these proteins could be phosphorylated by PtkA in vitro. Among these new substrates, single-stranded DNA exonuclease YorK, and aspartate semialdehyde dehydrogenase Asd were activated by PtkA-dependent phosphorylation. Because enzyme activity was not affected in other cases, we used fluorescent protein tags to study the impact of PtkA on localization of these proteins in vivo. For several substrates colocalization with PtkA was observed, and more importantly, the localization pattern of the proteins enolase, YjoA, YnfE, YvyG, Ugd and SsbA was dramatically altered in DeltaptkA background. Our results confirm that PtkA can control enzyme activity of its substrates in some cases, but also reveal a new mode of action for PtkA, namely ensuring correct cellular localization of its targets.

Maize (Zea mays L.) root cap cells secrete a large variety of compounds including proteins via an amorphous gel structure called mucilage into the rhizosphere. In the present study, mucilage secreted by primary roots of 3-4 day old maize seedlings was collected under axenic conditions, and the constitutively secreted proteome was analyzed. A total of 2848 distinct extracellular proteins were identified by nanoLC-MS/MS. Among those, metabolic proteins (approximately 25%) represented the largest class of annotated proteins. Comprehensive sets of proteins involved in cell wall metabolism, scavenging of reactive oxygen species, stress response, or nutrient acquisition provided detailed insights in functions required at the root-soil interface. For 85-94% of the mucilage proteins previously identified in the relatively small data sets of the dicot species pea, Arabidopsis, and rapeseed, a close homologue was identified in the mucilage proteome of the monocot model plant maize, suggesting a considerable degree of conservation between mono and dicot mucilage proteomes. Homologues of a core set of 12 maize proteins including three superoxide dismutases and four chitinases, which provide protection from fungal infections, were present in all three mucilage proteomes investigated thus far in the dicot species Arabidopsis, rapeseed, and pea and might therefore be of particular importance.