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121.
The occurrence of intestinal parasites in swine slurry and their removal in activated sludge plants 总被引:1,自引:0,他引:1
Thirteen intensive pig farms and two activated sludge treatment plants for pig slurry in north-western Spain were studied from April 2005 to June 2006 in order to evaluate the presence of enteric pathogens (Cryptosporidium, Giardia and helminths) and the efficiency with which they were removed. These parasites were present on 53%, 7% and 38% of the farms studied, respectively, with concentrations of 10(4)-10(5) oocysts per litre (/L) for Cryptosporidium, 10(3)cysts/L for Giardia and 10(2)-10(3) eggs/L for helminths. The overall removal of parasites in the pig slurry treatment plants ranged from 86.7% to over 99.99%. The results revealed a constant reduction at each stage of the treatment system, with activated sludge processes being the most effective treatment in reducing pathogens in pig slurry, 78-81% for Cryptosporidium oocysts and over 99.9% for helminth eggs. A heat drying procedure for sludge removed 4.3 log units of Cryptosporidium oocysts, demonstrating the excellent effectiveness of this treatment for reducing pathogens in sludge intended to be applied to land. 相似文献
122.
Endogenous levels of two gibberellins, GA3 andGA20, were quantified in unimbibed Onopordumnervosum seeds collected from two different populations, whichshoweddifferences in their germination capacity. After purifying the seed extracts,gibberellin levels were evaluated by gas chromatography mass spectrometry byusing selected ion monitoring (GC-MS-SIM) adding deuterated gibberellins asinternal standards. The intraspecific differences in germination capacity wereassociated with differences in the endogenous levels of both gibberellins. Thecontents of GA3 and GA20 in seeds with high germinationrate were twice and five times higher, respectively, than those from seeds witha low germination rate, indicating a possible role of gibberellins in dormancyrelease in this plant species. 相似文献
123.
A 2-year experimental study on nutrient and predator influences on food web constituents in a shallow lake of north-west Spain 总被引:3,自引:0,他引:3
Margarita Fernández-Aláez Camino Fernández-Aláez Eloy Bécares María Valentín Joan Goma Pedro Castrillo 《Freshwater Biology》2004,49(12):1574-1592
1. A 2‐year study was carried out on the roles of nutrients and fish in determining the plankton communities of a shallow lake in north‐west Spain. Outcomes were different each year depending on the initial conditions, especially of macrophyte biomass. In 1998 estimated initial ‘per cent water volume inhabited’ (PVI) by submerged macrophytes was about 35%. Phytoplankton biomass estimated as chlorophyll a was strongly controlled by fish, whereas effects of nutrient enrichment were not significant. In 1999 estimated PVI was 80%, no fish effect was observed on phytoplankton biomass, but nutrients had significant effects. Water temperatures were higher in 1998 than in 1999. 2. In the 1998 experiment, cladoceran populations were controlled by fish and cyanobacteria were the dominant phytoplankton group. There were no differences between effects of low (4 g fresh mass m?2) and high (20 g fresh mass m?2) fish density on total zooplankton biomass, but zooplankton biomass was higher in the absence of fish. With the high plant density in 1999, fish failed to control any group of the zooplankton community. 3. Total biovolume of phytoplankton strongly decreased with increased nutrient concentrations in 1998, although chlorophyll a concentrations did not significantly change. At higher nutrient concentrations, flagellate algae became more abundant with likely growth rates that could have overcompensated cladoceran feeding rates. This change in phytoplankton community composition may have been because of increases in the DIN : SRP ratio. Both chlorophyll a concentration and total phytoplankton biovolume increased significantly with nutrients in the 1999 experiment. 4. A strong decline of submerged macrophytes was observed in both years as nutrients increased, resulting in shading by periphyton. This shading effect could account for the plant decline despite lower water turbidity at the very high nutrient levels in 1998. 相似文献
124.
125.
Chiaraluce Moretti Simone Trabalza Letizia Granieri Eloy Caballo-Ponce Giulia Devescovi Alberto Marco Del Pino Cayo Ramos Vittorio Venturi Harrold A. van den Burg Roberto Buonaurio Carlo Alberto Palmerini 《Molecular Plant Pathology》2019,20(5):716-730
In a number of compatible plant-bacterium interactions, a rise in apoplastic Ca2+ levels is observed, suggesting that Ca2+ represents an important environmental clue, as reported for bacteria infecting mammalians. We demonstrate that Ca2+ entry in Pseudomonas savastanoi pv. savastanoi (Psav) strain DAPP-PG 722 is mediated by a Na+/Ca2+ exchanger critical for virulence. Using the fluorescent Ca2+ probe Fura 2-AM, we demonstrate that Ca2+ enters Psav cells foremost when they experience low levels of energy, a situation mimicking the apoplastic fluid. In fact, Ca2+ entry was suppressed in the presence of high concentrations of glucose, fructose, sucrose or adenosine triphosphate (ATP). Since Ca2+ entry was inhibited by nifedipine and LiCl, we conclude that the channel for Ca2+ entry is a Na+/Ca2+ exchanger. In silico analysis of the Psav DAPP-PG 722 genome revealed the presence of a single gene coding for a Na+/Ca2+ exchanger (cneA), which is a widely conserved and ancestral gene within the P. syringae complex based on gene phylogeny. Mutation of cneA compromised not only Ca2+ entry, but also compromised the Hypersensitive response (HR) in tobacco leaves and blocked the ability to induce knots in olive stems. The expression of both pathogenicity (hrpL, hrpA and iaaM) and virulence (ptz) genes was reduced in this Psav-cneA mutant. Complementation of the Psav-cneA mutation restored both Ca2+ entry and pathogenicity in olive plants, but failed to restore the HR in tobacco leaves. In conclusion, Ca2+ entry acts as a ‘host signal’ that allows and promotes Psav pathogenicity on olive plants. 相似文献
126.
127.
Cornelissen G Halberg F Wendt HW Bingham C Sothern RB Haus E Kleitman E Kleitman N Revilla MA Revilla M Breus TK Pimenov K Grigoriev AE Mitish MD Yatsyk GV Syutkina EV 《Biologia》1996,51(6):749-756
In several human adults, certain solar activity rhythms may influence an about 7-day rhythm in heart rate. When no about-weekly feature was found in the rate of change in sunspot area, a measure of solar activity, the double amplitude of a circadian heart rate rhythm, approximated by the fit of a 7-day cosine curve, was lower, as was heart rate corresponds to about-weekly features in solar activity and/or relates to a sunspot cycle. 相似文献
128.
Inhibition and repression of homocitrate synthase by lysine in Penicillium chrysogenum 总被引:9,自引:3,他引:6
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J M Luengo G Revilla M J López J R Villanueva J F Martín 《Journal of bacteriology》1980,144(3):869-876
Homocitrate synthase in the first enzyme of the lysine biosynthetic pathway. It is feedback regulated by L-lysine. Lysine decreases the biosynthesis of penicillin (determined by the incorporation of [14C]valine into penicillin) by inhibiting and repressing homocitrate synthase, thereby depriving the cell of alpha-aminoadipic acid, a precursor of penicillin. Lysine feedback inhibited in vivo the biosynthesis and excretion of homocitrate by a lysine auxotroph, L2, blocked in the lysine pathway after homocitrate. Neither penicillin nor 6-aminopenicillanic acid exerted any effect at the homocitrate synthase level. The molecular mechanism of lysine feedback regulation in Penicillium chrysogenum involved both inhibition of homocitrate synthase activity and repression of its synthesis. In vitro studies indicated that L-lysine feedback inhibits and represses homocitrate synthase both in low- and high-penicillin-producing strains. Inhibition of homocitrate synthase activity by lysine was observed in cells in which protein synthesis was arrested with cycloheximide. Maximum homocitrate synthase activity in cultures of P. chrysogenum AS-P-78 was found at 48 h, coinciding with the phase of high rate of penicillin biosynthesis. 相似文献
129.
Distribution of Foliar-applied Boron Measured by Spark-source Mass Spectrometry and Laser-probe Mass Spectrography 总被引:1,自引:0,他引:1
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The distribution of foliar-applied boron ([10B]boric acid) in radish (Raphanus sativus L.) was studied using for analysis of the stable isotopes a technique allowing a high sensitivity: spark-source mass spectrometry. Boron was recovered in the nontreated aerial parts and in the roots; however, the greatest fraction was in the treated leaf. It was possible with a laser-probe mass spectrograph to show that boron was not superficially located in the treated area but was present in tissues at all levels of depth considered. 相似文献
130.
Isabel Fabregat Elisa Revilla Dr Alberto Machado 《Molecular and cellular biochemistry》1987,74(1):77-81
The changes in the activity of the pentose phosphate cycle and the malic enzyme produced by the activation or inhibition of different NADPH-consuming pathways have been studied. The inhibition of the fatty acid synthesis by kynurenate produced a decrease in the flux through the pentose phosphate cycle and a diminution in the malic enzyme pathway. The incubation of the adipocytes in the presence of ter-butyl-hydroperoxide, a compound which is metabolized via a NADPH-consuming pathway, produced a big increase in the pentose phosphate cycle and the malic enzyme activities. The regulation of these NADPH-producing pathways by the NADPH/NADP ratio is discussed. 相似文献