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161.
Armbrust EV Berges JA Bowler C Green BR Martinez D Putnam NH Zhou S Allen AE Apt KE Bechner M Brzezinski MA Chaal BK Chiovitti A Davis AK Demarest MS Detter JC Glavina T Goodstein D Hadi MZ Hellsten U Hildebrand M Jenkins BD Jurka J Kapitonov VV Kröger N Lau WW Lane TW Larimer FW Lippmeier JC Lucas S Medina M Montsant A Obornik M Parker MS Palenik B Pazour GJ Richardson PM Rynearson TA Saito MA Schwartz DC Thamatrakoln K Valentin K Vardi A Wilkerson FP Rokhsar DS 《Science (New York, N.Y.)》2004,306(5693):79-86
Diatoms are unicellular algae with plastids acquired by secondary endosymbiosis. They are responsible for approximately 20% of global carbon fixation. We report the 34 million-base pair draft nuclear genome of the marine diatom Thalassiosira pseudonana and its 129 thousand-base pair plastid and 44 thousand-base pair mitochondrial genomes. Sequence and optical restriction mapping revealed 24 diploid nuclear chromosomes. We identified novel genes for silicic acid transport and formation of silica-based cell walls, high-affinity iron uptake, biosynthetic enzymes for several types of polyunsaturated fatty acids, use of a range of nitrogenous compounds, and a complete urea cycle, all attributes that allow diatoms to prosper in aquatic environments. 相似文献
162.
Frank van Langevelde Jody A. Ettema Maurice Donners Michiel F. WallisDeVries Dick Groenendijk 《Biological conservation》2011,(9):2274-2281
During the last decades, artificial night lighting has increased globally, which largely affected many plant and animal species. So far, current research highlights the importance of artificial light with smaller wavelengths in attracting moths, yet the effect of the spectral composition of artificial light on species richness and abundance of moths has not been studied systematically. Therefore, we tested the hypotheses that (1) higher species richness and higher abundances of moths are attracted to artificial light with smaller wavelengths than to light with larger wavelengths, and (2) this attraction is correlated with morphological characteristics of moths, especially their eye size. We indeed found higher species richness and abundances of moths in traps with lamps that emit light with smaller wavelengths. These lamps attracted moths with on average larger body mass, larger wing dimensions and larger eyes. Cascading effects on biodiversity and ecosystem functioning, e.g. pollination, can be expected when larger moth species are attracted to these lights. Predatory species with a diet of mainly larger moth species and plant species pollinated by larger moth species might then decline. Moreover, our results indicate a size-bias in trapping moths, resulting in an overrepresentation of larger moth species in lamps with small wavelengths. Our study indicates the potential use of lamps with larger wavelengths to effectively reduce the negative effect of light pollution on moth population dynamics and communities where moths play an important role. 相似文献
163.
Earthworms (Oligochaeta: Lumbricidae) have substantial effects on the structure and fertility of soils with consequences for the diversity of plant communities and associated ecosystem functions. However, we still lack a clear understanding of the functional role earthworms play in terrestrial ecosystems, partly because easy-to-use methods to quantify their activities are missing. In this study, we tested whether earthworms and their casts can be dual-labelled with 15N and 13C stable isotopes by cultivating them in soil substrate amended with 15N ammonium nitrate and 13C-glucose. Additionally, we also wanted to know whether (i) earthworms from different functional groups (soil-feeders vs. litter-feeders) and their casts would differ in their incorporation of stable isotopes, (ii) if enrichment levels are higher if the same amount of isotopes is applied in one dose or in staggered doses, and (iii) if isotopic enrichment in casts changes when they are stored in a conditioning cabinet or in a pot filled with soil placed in a greenhouse. Our findings show the feasibility of dual-labelling tissues and casts of both litter-feeding (Lumbricus terrestris) and soil-feeding (Aporrectodea caliginosa) earthworms using the same method. The advantage of this method is that earthworms and their casts can be labelled under realistic conditions by cultivating them for only four days in soil that received a one-time addition of commercially available stable isotopes instead of offering labelled plant material. In earthworms, the isotopic enrichment remained at a stable level for at least 21 days; labelled casts could be stored for at least 105 days without significantly decreasing their isotopic signals. This simple and efficient method opens new avenues for studying the role of these important ecosystem engineers in nutrient cycling and their functional relationships with other organisms. 相似文献
164.
Nielsen S Frank C Fruth A Spode A Prager R Graff A Plenge-Bönig A Loos S Lütgehetmann M Kemper MJ Müller-Wiefel DE Werber D 《Zoonoses and public health》2011,58(8):567-572
Infection with sorbitol-fermenting Shiga toxin-producing Escherichia coli O157:H- (sf STEC O157:H-) is rare, but emerging in Europe. The pathogen is typically isolated from paediatric patients with life-threatening haemolytic uraemic syndrome (HUS). It is unclear whether this observation primarily reflects the pathogen's virulence or its complex laboratory diagnosis, not routinely conducted in diarrhoeal patients. In summer 2009, four boys living in the same suburb in Germany developed diarrhoea-associated HUS: three were infected by sf STEC O157:H- and one died. We conducted two analytical epidemiological studies, an extensive search for diarrhoeal cases in potentially exposed groups, and an environmental investigation. Outbreak cases were residents of the suburb diagnosed with HUS, sf STEC O157:H- infection, or both between 24 July 2009 and 25 August 2009. Overall, we ascertained eight cases with a median age of 4 years (range: from 8 months to 9 years). Stool screening of 220 persons led to the identification of only four additional cases: two asymptomatic carriers and two diarrhoeal cases. HUS was strongly associated with visiting a local playground in July, particularly on 16th July (odds ratio = 42.7, P = 0.002). No other commonality, including food, was identified, and all environmental samples (n = 24) were negative. In this localized non-foodborne outbreak, the place of likely infection was a local playground. Sf STEC O157:H- infection apparently limits itself rarely to diarrhoeal illness and progresses frequently to HUS. Therefore, detection of and response to this hypervirulent pathogen primarily relies on HUS surveillance. 相似文献
165.
During the years 2008 to 2010 beetles of the genus Agriotes were monitored by means of pheromone traps in Rhineland-Palatinate. Each trap contained the female sexual pheromone of either Agriotes obscurus, A. sordidus, A. lineatus, A. sputator, or A. ustulatus. Beetles of these species could be caught, additionally also specimens of the species A. gallicus, A. acuminatus, and A. pilosellus. Specimens of A. brevis and A. proximus could not be caught, not even in traps with pheromones according to their species. The high frequency of A. sputator in the Upper Rhine Valley and mild river valleys was surprising. This might be an explanation for the increasing damages especially in potatoes during the past seven years. Also the species A. ustulatus occurred mainly in the Rhine Valley. The species A. obscurus was found predominantly in higher altitudes, A. lineatus and A. sputator appeared in the whole area, with varying frequencies. In all, we could determine the composition of Agriotes-species in 27 fields. In two fields traps were exposed in two subsequent years, in one field in three years. The changes in the populations are shown. The beetles collected in some fields were compared with the according wireworms. 相似文献
166.
BACKGROUND: Economic costs of spotted wing drosophila (SWD) include yield and associated revenue losses, labor and material costs for monitoring and management and revenue losses due to the closure of export markets should fruit from SWD‐infested regions be banned by trading partners. This analysis focuses on two types of loss in the California raspberry and strawberry industries: yield losses in the absence of management, and insecticide material costs on a per treatment basis. It computes the cost of a specific management program for raspberries in California's Central Coast region. RESULTS: Insecticide material and application costs per treatment and the cost of the management program are small relative to the yield losses in the absence of management that are observed by growers, researchers and others in initial infestations. CONCLUSION: It is difficult to evaluate precisely the share of pest management program costs due to SWD because insecticides are sometimes used to manage multiple pests, and because labor‐intensive field sanitation efforts to control SWD are recommended practices already. Given these considerations, this analysis finds that the benefits to SWD management well outweigh the costs examined here. Evaluating the efficacy of managing SWD is essential in assessing the risks that SWD poses and the benefits of pest management programs. Copyright © 2011 Society of Chemical Industry 相似文献
167.
Joseph Kyambadde Frank Kansiime Gunnel Dalhammar 《Water, air, and soil pollution》2005,165(1-4):37-59
In constructed wetlands (CWs) with horizontal sub-surface flow, nutrient removal, especially phosphorus, is limited because the root biomass fills the pore spaces of the substrate (usually gravel), directing wastewater flow to deeper wetland media; plants are not regularly harvested; the litter formed by decomposing vegetation remains on the surface of the substrate and thus does not interact with the wastewater; and the substrate media often used provide only limited adsorption. Effective nutrient removal including rootzone oxidation, adsorption and plant uptake therefore requires sufficient interaction of wastewater with the treatment media. We assessed the feasibility of biological nutrient removal from wastewater using substrate-free CWs with horizontal flow, planted with two tropical macrophytes namely, Cyperus papyrus and Miscanthidium violaceum. The objectives were to evaluate the system treatment efficiency under semi-natural conditions, and to assess microbial and plant biomass contributions to nutrient removal in the CWs. Results showed high removal efficiencies for biochemical oxygen demand, ammonium-nitrogen (NH4–N) and phosphorus (P) fractions in papyrus-based CWs (68.6–86.5%) compared to Miscanthidium (46.7–61.1%) and unplanted controls (31.6–54.3%). Ammonium oxidizing bacteria in CW root–mats (108–109 cells/gram dry weight) and residual nitrite and nitrate concentrations in the water phase indicated active system nitrification. Papyrus showed higher biomass production and nutrient uptake, contributing 28.5% and 11.2%, respectively, of the total N and P removed by the system compared to 15% N and 9.3% P removed by Miscanthidium plants. Compared to literature values, nitrification, plant uptake and the overall system treatment efficiency were high, indicating a high potential of this system for biological nutrient removal from wastewaters in the tropics. 相似文献
168.
169.
We tested whether straw could induce higher N release from decomposing salal leaf litter, which ostensibly interferes with mineralization of N. We mixed forest floor material from two forest types with 15N-enriched salal leaf litter, and incubated the mixtures 3 years with and without straw amendments. The amounts of N, as well as the relative amounts of 15N, extracted in five fractions were, respectively, 29-93 and 25-82% lower in straw-amended forest floor. Results suggest that straw diverted microbial decomposition activity away from the more recalcitrant litter fractions. Previous reports of higher mineral-N availability in straw-amended forest floors are best explained by a fertilizer effect of straw as opposed to a ‘priming effect’. 相似文献
170.
Aguilar-Cisneros BO López MG Richling E Heckel F Schreier P 《Journal of agricultural and food chemistry》2002,50(26):7520-7523
By use of headspace SPME sampling and a PLOT column, on-line capillary gas chromatography-isotope ratio mass spectrometry was employed in the combustion (C) and the pyrolysis (P) modes (HRGC-C/P-IRMS) to determine the delta(13)C(VPDB) and delta(18)O(VSMOW) values of ethanol in authentic (n = 14) and commercial tequila samples (n = 15) as well as a number of other spirits (n = 23). Whereas with delta(13)C(VPDB) values ranging from -12.1 to -13.2 per thousand and from -12.5 to -14.8 per thousand similar variations were found for 100% agave and mixed tequilas, respectively, the delta(18)O(VSMOW) data differed slightly within these categories: ranges from +22.1 to +22.8 per thousand and +20.8 to +21.7 per thousand were determined for both the authentic 100% agave and mixed products, respectively. The data recorded for commercial tequilas were less homogeneous; delta(13)C(VPDB) data from -10.6 to -13.9 per thousand and delta(18)O(VSMOW) values from +15.5 to +22.7 per thousand were determined in tequilas of both categories. Owing to overlapping data, attempts to differentiate between white, rested, and aged tequilas within each of the two categories failed. In addition, discrimination of tequila samples from other spirits by means of delta(13)C(VPDB) and delta(18)O(VSMOW) data of ethanol was restricted to the products originating from C(3) as well as C(4)/CAM raw materials. 相似文献