Detection of a Cytosolic Glutamine Synthetase in Leaves of Nicotiana tabacum L. by Immunocytochemical Methods

Two glutamine synthetase (GS) polypeptides (44 and 39 kD) were immunodetected on western blots of leaf extracts from tobacco (Nicotiana tabacum L.), a plant that has been reported to contain only chloroplast GS in the leaves. By immunocytochemical methods, we confirmed the localization of GS in the cytosol of cells in the vascular tissue and in the chloroplasts of mesophyll cells.     

Immunocytolocalization of glutamine synthetase in mesophyll and phloem of leaves ofSolanum tuberosum L.

Summary Localization of glutamine synthetase inSolanum tuberosum leaves was investigated by techniques of Western tissue printing and immunogold electron microscopy. Anti-GS antibodies used in immunolocalization recognize two peptides (45 kDa and 42 kDa) on Western blots. Antibody stained tissue prints on nitrocellulose membranes allowed low resolution localization of GS. Immunostaining was most evident in the adaxial phloem of the leaf midribs and petiole veins. High-resolution localization of glutamine synthetase by immunogold electron microscopy revealed that this enzyme occurs in both the chloroplasts and the cytosol ofS. tuberosum leaf cells. However, GS was specifically associated with the chloroplasts of mesophyll cells and with the cytoplasm of phloem companion cells. The evidence for cell-specific localization of chloroplast and cytosolic GS presented here agrees with the recently reported cell-specific pattern of expression of GUS reporter gene, directed by promoters for chloroplast and cytosolic GS form in tobacco transgenic plants. These data provide additional clues to the interpretation of the functional role of these different isoenzymes and its relationship with their specific localization.Abbreviations BSA bovine serum albumin - EM electron microscope - GOGAT glutamate synthase - GS glutamine synthetase - GUS -glucuronidase - IgG immunoglobulin - PBS phosphate buffer saline - SDS-PAGE sodium dodecyl sulphate-polyacrylamide gel electrophoresis     

Semicontinuous ethanol fermentation of sugar cane blackstrap molasses by pressed yeast

Summary A mathematical model is proposed to explain the influence of the volume fraction of inoculum on the fermentation time and ethanol productivity in semicontinuous ethanol fermentation of sugar cane blackstrap molasses by pressed yeast.Nomenclature a, b, c, d constants, see equation (5) - E_o initial ethanol concentration - E_f final ethanol concentration - K₁, K₂, K₃ constants, see equation (1) - P ethanol productivity - P_c calculated values of P - P_e experimental values of P - r correlation coefficient - S_o initial TRS concentration - S_m TRS concentration of the feeding mash - T fermentation time (average of the experimental values) - T_c calculated value of T - T_e experimental value of T - TRS total reducing sugars calculated as glucose - U_o initial urea concentration - U_m urea concentration of the feeding mash - V reactor working volume - V_i volume of the inoculum - volume fraction of inoculum=V_i/V     

Hydrography and characteristics of the phytoplankton in shelf and oceanic waters off southeastern Brazil during winter (July/August 1982) and summer (February/March 1984)

The physical and chemical environment, and the phytoplankton primary production of southeastern Brazil were studied in relation to the general oceanographic structure during two research cruises (winter and summer). In each cruise, a total of 91 stations were occupied. Data were collected on the spatial distribution of nutrients, phytoplankton biomass and photosynthetic capacity over the coastal, shelf and oceanic areas off São Paulo, Paraná and Santa Catarina States.During wintertime, the mixing processes between tropical warm waters of the Brazil Current and subantarctic waters of the Malvinas Current formed strong environmental gradients. The drainings of Rio de La Plata and Lagoa dos Patos are transported northwards by coastal currents, enriching the shelf waters off Santa Catarina State with inorganic nutrients and consequently increasing the chlorophyll a to the highest concentrations (> 3.5 mg m ^–3) measured during the two cruises. In slope waters chlorophyll values were always low (0.05–0.45 mg m ^–3). The chlorophyll within the euphotic layer varied from 8.8–36.7 and 1.2–18.5 mg m^–2 during winter and summer, respectively.The surface photosynthetic rates during winter and summer cruises ranged respectively from 0.21–9.17 and 0.66–19.60 mgC/mgChl.a/h. The mean rates were higher in nearshore waters and decreased seaward.The thermal structure of the water column affected the vertical distribution of chlorophyll a and photosynthesis within the euphotic zone; During unstratified periods (winter) they were uniformly distributed but the occurrence of subsurface peaks of chlorophyll and strong photosynthetic inhibition of low light adapted cells in deeper layers are associated to the seasonal thermocline. Occasionally, upwelling of deep waters from shelf break enriched the deeper euphotic layers in offshore areas. Intensive upwelling was observed off Paranagua Bay (Parana State) and the mechanisms of its formation are discussed.     

Inhibition of peroxidase by algal humic and fulvic acids

In contrast to their soil counterparts, algal fulvic acids were more inhibitory than the corresponding humic acids. Fulvic and humic acids fromFucus vesiculosus were more efficient than the correspondingLaminaria digitata acids in inactivating the enzyme.Laminaria humic acids, which have no phenolic hydroxyls, showed a concentration dependent inhibition hardly in accordance with the presumed role played by these groups in the activity of oxidases.     

Genetic variants of serum alpha1-antitrypsin (Pi types) in Portuguese.

The results of Pi typing on 330 Portuguese from the area of Lisbon are reported. We found six phenotypes and four alleles out of the 24 described in the literature. The allele PiM is the most frequent as in other populations, PiS shows a high frequency (0.1152), and PiF is absent, which agrees satisfactorily with former studies carried out in Spain. These results are compared with others and the entity of the Iberian population is evoked.     

EFFECTS OF LOW NITROGEN LEVELS AND VARIOUS NITROGEN SOURCES ON GROWTH AND WHORL DEVELOPMENT IN ACETABULARIA (CHLOROPHYTA)1

Nitrate, ammonia, urea, and glycine were compared as nitrogen sources for Acetabularia mediterranea. Cells grew normally in media containing nitrate or urea, while cells did not grow at all when the same amount of N was supplied as ammonium ion. The utilization of glycine remains questionable. Cells in medium without added N (NDM) increased in length and some formed reproductive caps. The whorls of vegetative cells showed considerable hypertrophy in NDM and in glycine. This hypertrophy was due to the elongation of only the first-(a₁) and second- (a₂) order articles. When cut, the basal portion of cells without added N regenerated new apices with whorls. The development of these whorls was inversely proportional to the NO₂ concentration. Analyses showed that the intracellular nitrogen pool in young cells and regenerating bases was very small, about 1/10 of that of fully grown cells. Therefore we suggest that trace amounts of N contaminants in the medium supported growth and development, the uptake of which was facilitated by the hypertrophied whorls, under N-limited conditions.     

Cryptogenic hepatitis patients have a higher Bartonella sp.-DNA detection in blood and skin samples than patients with non-viral hepatitis of known cause

BackgroundThis study aimed to assess the prevalence of Bartonella sp.-DNA detection in blood and skin samples from patients with non-viral end-stage liver disease awaiting liver transplantation.Methodology/Principal findingsBlood samples and healthy skin fragments from 50 patients were tested using microbiological and molecular methods. Fifteen patients had cryptogenic hepatitis (CH) and 35 had alcoholic, drug-induced or autoimmune liver disease. DNA was extracted from whole blood and liquid culture samples, isolates, and skin fragments. Thirteen of the 50 patients (26%) had Bartonella henselae DNA detection in their blood (9/50) and/or skin (5/50) samples. Colonies were isolated in 3/50 (6%) and infection was detected in 7/50 (14%) of the 50 patients. B. henselae-DNA detection was more prevalent in patients with CH than in other patients (p = 0.040). Of 39 patients followed-up for at least two years, a higher mortality rate was observed among patients with CH infected with B. henselae (p = 0.039).Conclusions/SignificanceFurther studies assessing the role of B. henselae infection in the pathogenesis of hepatitis patients must be urgently conducted.     

Ecology,morphology and physiology of Chroothece richteriana (Rhodophyta,Stylonematophyceae) in the highly calcareous Río Chícamo,south-east Spain

The ecology of Chroothece was studied in the highly calcareous Río Chícamo, south-east Spain, in order to explain its success there, but rarity elsewhere. The river, which originates mainly from an underground aquifer, has water with high conductivity, sulphate and nitrate but low phosphate concentrations, the latter mainly organic. Chroothece occurs in mats and in lobed colonies reaching 4 cm in the broadest dimension. The colony surface consists of one layer of cells, each of which is attached to a stalk, which dichotomizes when the cell divides; stalks often extend to the colony base. The central region of many mat cells and almost all colony cells has a yellow to orange-brown colour, associated with the numerous lipid droplets densely covering the surface of the pyrenoid and arms of the star-shaped chloroplast. Field material and laboratory isolates indicate that stalk formation occurs under moderate P limitation and both stalks and cell sheath show high phosphatase activities. This also occurred in a culture collection strain maintained for 30 years in a very P-rich medium, but then transferred to a moderately P-limiting medium (c. 0.9 mg l^?1). We suggest that colony formation is initiated by aggregation of motile cells following P pulses in the water. Comparisons are made with Rivularia, a competitor in this nitrate-rich river, in spite of being a N₂-fixer. One difference is that Chroothece cells lie at the periphery of the colonies and are therefore exposed to maximum sunlight, whereas Rivularia trichomes grow inside colonies with photoprotection by scytonemin. However, the ability to withstand heavy grazing pressure may be an especially important factor favouring Rivularia here.