Transport and metabolism of exogenously applied gibberellins to Malus domestica Borkh. cv. Jonagold

The radio-labeled gibberellins GA₁, GA₃,GA₄, and GA₇ were applied to intact developing applefruits (Malus domestica Borkh. cv. Jonagold) during theperiod when GAs are suggested to inhibit flower bud induction for the followingyear. Radioactivity from these compounds was found to be transported intoadjacent tissues as there are pedicels and bourses (4%). Application topedicels, after removal of the fruits, enhanced the transport into adjacentbourses up to 11%. The bud-carrying lateral bourse shoots contained onlyminor amounts of radioactivity on average 0.4% in both cases. Theseexport rates were identical, 1 or 5 days after application.After application of the corresponding deuterium-labeled GAs and analyses bymass spectrometry the specific metabolization of GA₁ toGA₁ 13-O-glucoside and of GA₃ to GA₃13-O-glucoside was demonstrated. Additional metabolites of GA₁ andGA₃ were not detected. After fruit application of GA₃ theratio of GA₃ to GA₃ 13-O-glucoside was found to be 1:2 inthe fruit. Pedicel application led to ratios of 1:4 and 1:5, respectively, inthe pedicel and in the adjacent bourse. After the application of GA₄and GA₇, neither glucosylation products nor other GA-like metabolitescould be identified.This is the first report of the metabolism of GAs to GA 13-O-glucosides indeveloping apple fruits. The possible function of the GAs as a signal in flowerbud formation for the following year is discussed.     

Multifunctional Centromere Binding Factor 1 Is Essential for Chromosome Segregation in the Human Pathogenic Yeast Candida glabrata

The CBF1 (centromere binding factor 1) gene of Candida glabrata was cloned by functional complementation of the methionine biosynthesis defect of a Saccharomyces cerevisiae cbf1 deletion mutant. The C. glabrata-coded protein, CgCbf1, contains a basic-helix-loop-helix leucine zipper domain and has features similar to those of other budding yeast Cbf1 proteins. CgCbf1p binds in vitro to the centromere DNA element I (CDEI) sequence GTCACATG with high affinity (0.9 x 10(9) M(-1)). Bandshift experiments revealed a pattern of protein-DNA complexes on CgCEN DNA different from that known for S. cerevisiae. We examined the effect of altering the CDEI binding site on CEN plasmid segregation, using a newly developed colony-sectoring assay. Internal deletion of the CDEI binding site led only to a fivefold increase in rates of plasmid loss, indicating that direct binding of Cbf1p to the centromere DNA is not required for full function. Additional deletion of sequences to the left of CDEI, however, led to a 70-fold increase in plasmid loss rates. Deletion of the CBF1 gene proved to be lethal in C. glabrata. C. glabrata cells containing the CBF1 gene under the influence of a shutdown promoter (tetO-ScHOP) arrested their growth after 5 h of cultivation in the presence of the reactive drug doxycycline. DAPI (4',6'-diamidino-2-phenylindole) staining of the arrested cells revealed a significant increase in the number of large-budded cells with single nuclei, 2C DNA content, and short spindles, indicating a defect in the G(2)/M transition of the cell cycle. Thus, we conclude that Cbf1p is required for chromosome segregation in C. glabrata.     

Trophoblast-like human choriocarcinoma cells serve as a suitable in vitro model for selective cholesteryl ester uptake from high density lipoproteins.

As human choriocarcinoma cells display many of the biochemical and morphological characteristics reported for in utero invasive trophoblast cells we have studied cholesterol supply from high density lipoproteins (HDL) to these cells. Binding properties of 125I-labeled HDL subclass 3 (HDL3) at 4 degrees C were similar for BeWo, JAr, and Jeg3 choriocarcinoma cell lines while degradation rates at 37 degrees C were highest for BeWo. Calculating the selective cholesteryl ester (CE)-uptake as the difference between specific cell association of [3H]CE-labeled HDL3 and holoparticle association of 125I-labeled HDL3 revealed that in BeWo cells, the selective CE-uptake was slightly lower than holoparticle association. However, the pronounced capacity for specific cell association of [3H]CE-HDL3 and selective [3H]CE-uptake in excess of HDL3-holoparticle association, and cAMP-mediated enhanced cell association of [3H]CE-HDL3 in JAr and Jeg3 suggested the scavenger receptor class B, type I (SR-BI) to be responsible for this pathway. Abundant expression of SR-BI (but not SR-BII, a splice variant of SR-BI) could be observed in JAr and Jeg3 but not in BeWo cells using RT-PCR, Northern and Western blot analysis, and immunocytochemical technique. Adenovirus-mediated overexpression of SR-BI in all three choriocarcinoma cell lines resulted in an enhanced capacity for cell association of [3H]CE-HDL3 (20-fold in BeWo; fivefold in JAr and Jeg3). The fact that exogenous HDL3 remarkably increases proliferation in JAr and Jeg3 supports the notion that selective CE-uptake and subsequent intracellular generation of cholesterol is coupled to cellular growth. From our findings we propose that JAr and Jeg3 cells serve as a suitable in vitro model to study selective CE-supply to human placental cells.     

Production of phytohormones by root-associated saprophytic actinomycetes isolated from the actinorhizal plant Ochetophila trinervis

The aim of the present study was to evaluate phytohormone production by symbiotic and saprophytic actinomycetes isolated from the actinorhizal plant Ochetophila trinervis which had previously proved to stimulate nodulation by Frankia. Three saprophytic strains out of 122, isolated from the rhizosphere of this plant with multiple enzymatic activities were selected for plant growth experiments in pots: Streptomyces sp. (BCRU-MM40), Actinoplanes sp. (BCRU-ME3) and Micromonospora sp. (BCRU-MM18). For experiments, the symbiotic N₂-fixing strain Frankia (BCU110501), isolated from nodules of the same actinorhizal plant was used. Phytohormone production was evaluated in supernatant of non-inoculated and inoculated culture media in exponential growth phase. Indole 3-acetic acid (IAA) and gibberellic acid (GA₃) were analyzed by gas chromatography-mass spectrometry (GC–MS), while zeatine (Z) production was determined by gas chromatography-flame ionization detector and high performance liquid chromatography (HPLC fluorescent and UV). The levels of the three phytohormones produced by the saprophytic rhizoactinomycetes were higher than that produced by the symbiotic Frankia strain. Zeatine biosynthesis was higher (μg ml⁻¹) than IAA and GA₃ (ng ml⁻¹), and Micromonospora strain produced the highest levels of these phytohormones. Although O. trinervis has been shown to be intercellularly infected by Frankia without mediation of root hair deformation, when plants were co-inoculated with actinomycetes’ culture, some root hair deformation was observed. This is the first report on identification of IAA, GA₃ and Z in saprophytic actinomycetes and their potential role in plant–microbe interaction.     

The Immunome of Colon Cancer: Functional In Silico Analysis of Antigenic Proteins Deduced from IgG Microarray Profiling

Characterization of the colon cancer immunome and its autoantibody signature from differentially-reactive antigens (DIRAGs) could provide insights into aberrant cellular mechanisms or enriched networks associated with diseases. The purpose of this study was to characterize the antibody profile of plasma samples from 32 colorectal cancer (CRC) patients and 32 controls using proteins isolated from 15,417 human cDNA expression clones on microarrays. 671 unique DIRAGs were identified and 632 were more highly reactive in CRC samples. Bioinformatics analyses reveal that compared to control samples, the immunoproteomic IgG profiling of CRC samples is mainly associated with cell death, survival, and proliferation pathways, especially proteins involved in EIF2 and mTOR signaling. Ribosomal proteins (e.g., RPL7, RPL22, and RPL27A) and CRC-related genes such as APC, AXIN1, E2F4, MSH2, PMS2, and TP53 were highly enriched. In addition, differential pathways were observed between the CRC and control samples. Furthermore, 103 DIRAGs were reported in the SEREX antigen database, demonstrating our ability to identify known and new reactive antigens. We also found an overlap of 7 antigens with 48 “CRC genes.” These data indicate that immunomics profiling on protein microarrays is able to reveal the complexity of immune responses in cancerous diseases and faithfully reflects the underlying pathology.     

Rhythmic mycelial growth in Podospora anserina

Summary Treatment of mycelial fragments with EMS and NMU yielded 15 revertants of the pleiotropic mutant zonata of Podospora anserina. Analysis by biological, biochemical and genetical methods has revealed that the reversions are caused by back mutation within the zonata locus. This leads to the conclusion that a point mutation causes the morphological and biochemical alterations in this mutant.A working hypothesis for the primary action of this gene and its significance for the elucidation of morphogenesis and of pleiotropism are discussed.With support of the Deutsche Forschungsgemeinschaft, Bad Godesberg (Germany).     

Co-infection by Cryptococcus neoformans and Mycobacterium aKeikawusvium intracellulare in AIDS

In the observation of various opportunistic pathogens in HIV-positive persons, co-infection by Cryptococcus neoformans together with Mycobacterium avium intracellulare was found if there was a CD4 lymphocyte count as low as 3–20μl. In 1540 HIV-positive patients under treatment at a Berlin hospital (Auguste–Viktoria–Krankenhaus) during 1985–1994, all AIDS-relevant diseases were examined in a multivariate analysis as variables of influence on the manifestation of a systemic Mycobacterium avium complex (MAC) infection. The analysis involved data on 36 cases of cryptococcosis and 202 cases with a typical clinical course in whom MAC had been detected at sterile body sites. As significant and independent factors of influence, the following were identified: C. neoformans infection, wasting syndrome, lower age, low CD4 lymphocyte count and preceding Pneumocystis carinii pneumonia (PcP) prophylaxis. Cryptococcosis ranged first with an odds ratio of 2.75. The concomitant manifestation of cryptococcosis and systemic MAC infection in six patients is shown. Because both opportunists, C. neoformans and avian mycobacteria, may have their common habitat in droppings of defined species of pet birds, a common source of infection deserves further clinical and epidemiological attention. This revised version was published online in August 2006 with corrections to the Cover Date.     

Über die Rolle longitudinaler und radialer Polaritäts-gradienten bei der Gewebedifferenzierung von Pflanzen

Zusammenfassung Störung der Zellpolarität durch Colchicin führt zu einer Beeinträchtigung oder Verhinderung der von dieser Polarität abhängigen Differenzierungen. Bei jungen Blättern vonSphagnum kann das normale Muster der Differenzierung in Chlorophyll- und Hyalinzellen verhindert werden. Sind die Hyalinzellen schon angelegt, so kann die Ausbildung der Yerdickungsleisten in ihnen unterbleiben. Statt dessen erfolgt dann eine ungeordnete, d. h. gleichmäßig über die ganze Fläche verteilte Auflagerung von Zellulose.Aus negativ verlaufenen Versuchen zur Beeinflussung der Differenzierung im Kallusgewebe und in Gewebekulturen durch Variation der Sauerstoff- und Kohlendioxydkonzentrationen sowie der Luftfeuchtigkeit wird geschlossen, daß die normalerweise im Sproß bestehenden Gradienten dieser Faktoren nicht für die Differenzierungsgradienten in ihm entscheidend sein können. Für die Differenzierungsgradienten müssen vielmehr rein physiologische Faktoren ausschlaggebend sein. D. h. die radiale Polarität ist für die unterschiedliche Differenzierung in verschiedenen Sproßtiefen verantwortlich.Es wird darauf hingewiesen, daß durch Unterdrückung der Polarität am Vegetationspunkt die Inäqualität der Teilungen verlorengeht und der Übergang zur Blütenbildung als Folge solcher Unterdrückung aufgefaßt werden kann. Dadurch wird die behauptete Apolarität des Auxinstromes in blütenbildenden Sprossen, aber z. B. auch die Erschwerung inäqualer Teilungen in Blattorganen der Blütenregion verständlich. So kann man u. a. das Fehlen von Spaltöffnungen in Hochblättern und das ausschließliche Vorkommen von Chlorophyllzellen in den Perichaetialblättern vonSphagnum deuten.Der Deutschen Forschungsgemeinschaft danken wir für die Unterstützung der Untersuchungen.     

The Gustatory Neural Response Function

With few exceptions, afferent neurons in the various sensory systems respond to wide ranges of stimuli. In those sensory systems for which the stimulus dimensions are understood, the response functions of these neurons may be described; they are usually simple functions with one maximum, although many variations exist. In the chemical senses, the stimulus dimensions are not known, and thus the neural response functions of these neurons have never been described. The present paper presents methods to determine these response functions and the stimulus dimensions for the chemical senses. A tentative response function for taste is developed, and preliminary steps are taken toward disclosing the stimulus dimensions.