Catecholamines in the coelenterate Renilla köllikeri

Summary The characteristics of uptake of ³H-noradrenaline (³H-NA) and ³H-adrenaline (³H-A) in the tissues of the sea pansy, Renilla köllikeri, were studied by in vivo incubations. Lineweaver-Burk plots indicated two components of catecholamine accumulation, one representing a high-affinity uptake with an apparent K _m of 4.91×10^-7 M (³H-NA) or 4.39×10^-7 M (³H-A), and the other a low affinity process with an apparent Km of 5.52×10^-5 M (³H-NA) or 1.49×10^-5 M (³H-A). The high-affinity uptake of both tracers was strongly inhibited at low temperature and in a calcium-free medium, thus suggesting the involvement of a carrier-mediated transport mechanism, but was largely insensitive to sodium omission and ouabain. Accumulations of ³H-NA, but not ³H-A, were highly desipramine-sensitive.Light-microscopic radioautographic studies demonstrated the presence of cells reactive to both ³H-NA and ³H-A in the ectoderm, mesoglea and endoderm. Extraneuronal accumulations of ³H-NA and ³H-A were prominent in some ectodermal cells, in amoebocytes and spicule cells. Reactive neuronal processes were tentatively identified throughout the mesoglea and over all muscle layers on the basis of several morphological criteria. ³H-A, but not ³H-NA label, was more intense over the presumed photocytic zone and circular muscle than elsewhere. These and other observations support a neurotransmitter role for adrenaline (and probably noradrenaline) in control of luminescence and modulation of slow rachidial contractions.Supported by a grant from the Natural Sciences and Engineering Research Council of Canada     

Comparative proteomics of leaf,stem, and root tissues of synthetic Brassica napus

Comparative proteomics was applied to three vegetative organs of Brassica napus, the leaf, stem, and root using 2‐DE. Among the >1600 analyzed spots, 43% were found to be common to all three organs, suggesting the existence of a “basal” or ubiquitous proteome composed of housekeeping proteins. The green organs, leaf, and stem, were closely related (～80% common spots) while the root displayed more organ‐specific polypeptides (～10%). Reference maps were established using MS, allowing the identification of 93, 385, and 266 proteins in leaf, stem, and root proteomes, respectively. Bioinformatic analyses were also performed; in silico functional categorization and cellular localization allow obtaining a precise picture of the cell molecular network within vegetative organs. These proteome maps can be explored using the PROTICdb software at the following address: http://bioinformatique.moulon.inra.fr/proticdb/web_view/.     

NITZSCHIA ALICAE SP. NOV. AND N. PURIFORMIS SP. NOV., NEW DIATOMS FROM EUROPEAN RIVERS AND COMPARISON WITH THE TYPE MATERIAL OF N. SUBLINEARIS AND N. PURA1

Nitzschia sublinearis Hustedt and N. pura Hustedt are common oligosaprobic freshwater diatom species that frequently occur in diatom inventories, thus being important in water quality studies. Both are considered as species with overlapping diagnostic criteria in several floras, which is typical of the whole genus Nitzschia. The type material of Hustedt of N. sublinearis and N. pura was examined using LM and EM in order to document the range of variation within the type populations and to compare it with populations occurring in different European rivers. Detailed observations allowed recognition of two new freshwater diatom species: N. alicae sp. nov., occurring in mesotrophic up to eutrophic conditions, and N. puriformis sp. nov., mostly occurring in oligotrophic habitats, both in rivers and streams at middle and high altitudes. The most reliable taxonomic features that separate both new species from the most similar taxa are the density of fibulae and striae, valve shape, and valve width as well as the shape of areolae. Morphological examination of different populations indicates that N. puriformis is relatively common in European rivers and has been overlooked to date and confounded with N. pura by several researchers. By contrast, N. alicae has, to date, been collected only in Slovakia and Northern Italy, but with a high frequency of occurrence and sometimes in high abundance at sites.     

Inhibition of Paracoccidioides lutzii Pb01 Isocitrate Lyase by the Natural Compound Argentilactone and Its Semi-Synthetic Derivatives

The dimorphic fungus Paracoccidioides spp. is responsible for paracoccidioidomycosis, the most prevalent systemic mycosis in Latin America, causing serious public health problems. Adequate treatment of mycotic infections is difficult, since fungi are eukaryotic organisms with a structure and metabolism similar to those of eukaryotic hosts. In this way, specific fungus targets have become important to search of new antifungal compound. The role of the glyoxylate cycle and its enzymes in microbial virulence has been reported in many fungal pathogens, including Paracoccidioides spp. Here, we show the action of argentilactone and its semi-synthetic derivative reduced argentilactone on recombinant and native isocitrate lyase from Paracoccidioides lutzii Pb01 (PbICL) in the presence of different carbon sources, acetate and glucose. Additionally, argentilactone and its semi-synthetic derivative reduced argentilactone exhibited relevant inhibitory activity against P. lutzii Pb01 yeast cells and dose-dependently influenced the transition from the mycelium to yeast phase. The other oxygenated derivatives tested, epoxy argentilactone and diol argentilactone-, did not show inhibitory action on the fungus. The results were supported by in silico experiments.     

Pulmonary fluid balance following pulmocutaneous baroreceptor denervation in the toad

Pulmonary hemodynamics and net transcapillary fluid flux (NTFF) were measured in conscious toads before and following bilateral denervation of the recurrent laryngeal nerves (rLN), which contain afferents from baroreceptors located in the pulmocutaneous arteries. Denervation caused an acute doubling of the arterial-venous pressure gradient across the lung and a threefold increase in pulmonary blood flow. Calculated pulmonary vascular resistance fell and remained below control values through the period of experimentation. NTFF increased by an order of magnitude (0.74-7.77 ml X kg-1 X min-1), as filtration increased in response to the hemodynamic changes caused by rLN denervation. There was a better correlation between NTFF and pulmonary blood flow than between NTFF and pulmonary driving pressure. Our results support the view that tonic neural input from pulmocutaneous baroreceptors protects the anuran lung from edema by restraining pulmonary driving pressure and blood flow and perhaps by reflexly maintaining vascular tone in the extrinsic pulmonary artery, therefore tending to increase the pre-to-postpulmonary capillary resistance ratio and biasing the Starling relationship in the pulmonary capillaries against filtration.     

The Microbial Diversity of Traditional Spontaneously Fermented Lambic Beer

Lambic sour beers are the products of a spontaneous fermentation that lasts for one to three years before bottling. The present study determined the microbiota involved in the fermentation of lambic beers by sampling two fermentation batches during two years in the most traditional lambic brewery of Belgium, using culture-dependent and culture-independent methods. From 14 samples per fermentation, over 2000 bacterial and yeast isolates were obtained and identified. Although minor variations in the microbiota between casks and batches and a considerable species diversity were found, a characteristic microbial succession was identified. This succession started with a dominance of Enterobacteriaceae in the first month, which were replaced at 2 months by Pediococcus damnosus and Saccharomyces spp., the latter being replaced by Dekkera bruxellensis at 6 months fermentation duration.     

Biological control of Pythium aphanidermatum in cucumber with a combined application of Lysobacter enzymogenes strain 3.1T8 and chitosan

Pythium aphanidermatum (Edson) Fitzp., causing root and crown rot in cucumber, was successfully managed by Lysobacter enzymogenes strain 3.1T8. Greenhouse experiments were performed with cucumber plants grown in rockwool blocks up to 5 weeks with a recirculated nutrient solution. Application of L. enzymogenes 3.1T8 in combination with chitosan (the deacetylated derivative of chitin) reduced the number of diseased plants by 50–100% in four independent experiments relative to the Pythium control. Application of chitosan or the bacterial inoculant alone was not effective. Washed bacterial cells plus chitosan inhibited Pythium-induced disease, but the supernatant without bacterial cells combined with chitosan was not effective. The most effective and convenient type of commercially available chitosan was selected. Chitosan disappeared from the hydroponic system within 24 h after application, which we attribute to enzyme expression of L. enzymogenes 3.1T8 induced by the exposure to chitosan. Plate counts of the nutrient solution on a general bacterial medium showed the dominance of the inoculated strain, and an increased bacterial population growing on chitin and chitosan as single carbon source. The population density of L. enzymogenes 3.1T8 on the cucumber roots was investigated with a strain specific real-time TaqMan PCR. Highest chitosan concentrations applied (0.1 and 0.03 g/plant) resulted in the highest numbers of L. enzymogenes 3.1T8 present on roots; i.e. 10⁸–10⁹ cells/g root. Substantially higher numbers of bacterial cells were observed by scanning electron microscopy after application of chitosan; no morphological or other qualitative differences were found. The results indicate that addition of chitosan enhanced the biocontrol efficacy of L. enzymogenes 3.1T8; either chitosan serves as C- and N-source for the antagonist, induces antagonistic gene expression, or both.     

On the relationship between vertical microdistribution and adaptations to oxygen stress in littoral Chironomidae (Diptera)

Animals that dwell at different depths in the sediment, are adapted to different respiratory environments. It is possible that animals that occur deep in the sediment have a higher hemoglobin concentration than surface-dwelling animals. To test this hypothesis, hemoglobin concentrations and weights of eight chironomid species that dwell in the littoral zone were measured. High hemoglobin concentration and weight both seemed to contribute to an ability to cope with low oxygen concentrations, and determined the vertical distribution of chironomids in the sediment. A multiple regression equation, including these factors, was derived. It may be used to predict the median depth of occurrence for species that were not included in this study. High sensitivity of small animals to oxygen stress is discussed from a theoretical point of view.Research Assistant of the Belgian National Fund for Scientific ResearchResearch Assistant of the Belgian National Fund for Scientific Research