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101.
102.
Hepatitis A virus (HAV) is currently recognized as an important human food borne pathogen, and it is one of the most resistant
enteric RNA viruses, is highly infectious, and may lead to widespread outbreaks. The aim of this study was to optimize the
methods to detect HAV from artificially contaminated food. To this end, strawberry and lettuce were experimentally contaminated
with HAV suspension containing 6 × 106 copies/ml. After contamination, HAV persistence and washing procedure were evaluated at 0, 1, 3, 7, and 9 days of storage.
Five elution buffers (PBS (pH 7.4)/0.1% Tween80; 50 mM glycine/3% (wt/vol) beef extract (pH 9.5); PBS (pH 7, 4); 25 mM glycine/0.1
Tween80; and 1 M sodium bicarbonate) were used to elute the virus, and qualitative and quantitative PCR were used for HAV
detection. HAV was detected by qualitative and quantitative PCR using any of the five elution buffers, but PBS was the most
effective. Even after washing, HAV was detected up to 9 days after contamination by quantitative PCR. Quantitative PCR was
more sensitive than qualitative PCR since samples containing viral load lower than 1.4 × 103 copies/ml could not be detected by qualitative PCR. Quantitative PCR can be used for rapid detection of food borne viruses
and will help in the monitoring and control of food borne disease. 相似文献
103.
Contamination of aquatic ecosystems with heavy metals has been receiving increased worldwide attention due to their harmful e ects
on human health and other organisms in the environment. Most of the studies dealing with toxic e ects of metals deal with single
metal species, while the aquatic organisms are typically exposed to mixtures of metals. Hence, in order to provide data supporting
the usefulness of freshwater fish as indicators of heavy metal pollution, it has been proposed in the present study to investigate the
bioaccumulation and depuration of chromium in the selected organs of freshwater fingerlings Cirrhinus mrigala, individually and in
binary solutions with nickel. The results show that the kidney is a target organ for chromium accumulation, which implies that it is also
the “critical” organ for toxic symptoms. The results further show that accumulation of nickel in all the tissues of C. mrigala is higher
than that of chromium. In addition, the metal accumulations of the binary mixtures of chromium and nickel are substantially higher
than those of the individual metals, indicating synergistic interactions between the two metals. Theoretically the simplest explanation
for an additive joint action of toxicants in a mixture is that they act in a qualitatively similar way. The observed data suggest that C.
mrigala could be suitable monitoring organisms to study the bioavailability of water-bound metals in freshwater habitats. 相似文献
104.
Caroline S. Chaboo Michael S. Engel Maria Lourdes Chamorro-Lacayo 《Die Naturwissenschaften》2009,96(9):1121-1126
Complex ethological adaptations and intraspecific interactions leave few fossil traces. We document three Dominican (20 million
years old [myo]) and Baltic (45 myo) amber fossils that exhibit firm evidence of highly integrated interactions between mothers
and offspring in the diverse camptosomate lineage of beetles (Chrysomelidae, leaf beetles). As in contemporary species, these
hard cases were initially constructed by mothers, then inherited and retained by offspring, which then elaborate this protective
domicile with an unusual but economical building material, their feces. The three fossils are classified in the Subfamily
Cryptocephalinae; two are classified in the tribe Chlamisini based on morphological evidence—the flattened head lacking a
sharp keel and long legs with simple recurved untoothed claws. These diagnostic features are not clearly visible in the third
specimen to permit more refined identification. These fossils provide more precise paleontological dating of tribal nodes
within the cryptocephaline radiation of leaf beetles. These fossils are the first and earliest evidence of mother–offspring
interaction, building behavior, and fecal recycling in Camptosomata beetles and of inheritance of architectural structures
in beetles. 相似文献
105.
Marek K. Jarecki Timothy B. Parkin Alvarus S.K. Chan Thomas C. Kaspar Thomas B. Moorman Jeremy W. Singer Brian J. Kerr Jerry L. Hatfield Raymond Jones 《Agriculture, ecosystems & environment》2009,134(1-2):29-35
Agriculture contributes 40–60% of the total annual N2O emissions to the atmosphere. Development of management practices to reduce these emissions would have a significant impact on greenhouse gas levels. Non-leguminous cover crops are efficient scavengers of residual soil NO3, thereby reducing leaching losses. However, the effect of a grass cover crop on N2O emissions from soil receiving liquid swine manure has not been evaluated. This study investigated: (i) the temporal patterns of N2O emissions following addition of swine manure slurry in a laboratory setting under fluctuating soil moisture regimes; (ii) assessed the potential of a rye (Secale cereale L.) cover crop to decrease N2O emissions under these conditions; and (iii) quantified field N2O emissions in response to either spring applied urea ammonium nitrate (UAN) or different rates of fall-applied liquid swine manure, in the presence or absence of a rye/oat winter cover crop. Laboratory experiments investigating cover crop effects N2O emissions were performed in a controlled environment chamber programmed for a 14 h light period, 18 °C day temperature, and 15 °C night temperature. Treatments with or without a living rye cover crop were treated with either: (i) no manure; (ii) a phosphorus-based manure application rate (low manure): or (iii) a nitrogen-based manure application rate (high manure). We observed a significant reduction in N2O emissions in the presence of the rye cover crop. Field experiments were performed on a fine-loamy soil in Central Iowa from October 12, 2005 to October 2, 2006. We observed no significant effect of the cover crop on cumulative N2O emissions in the field. The primary factor influencing N2O emission was N application rate, regardless of form or timing. The response of N2O emission to N additions was non-linear, with progressively more N2O emitted with increasing N application. These results indicate that while cover crops have the potential to reduce N2O emissions, N application rate may be the overriding factor. 相似文献
106.
European scale application of atmospheric reactive nitrogen measurements in a low-cost approach to infer dry deposition fluxes 总被引:1,自引:0,他引:1
Y.S. Tang I. Simmons N. van Dijk C. Di Marco E. Nemitz U. Dmmgen K. Gilke V. Djuricic S. Vidic Z. Gliha D. Borovecki M. Mitosinkova J.E. Hanssen T.H. Uggerud M.J. Sanz P. Sanz J.V. Chorda C.R. Flechard Y. Fauvel M. Ferm C. Perrino M.A. Sutton 《Agriculture, ecosystems & environment》2009,133(3-4):183
A European scale network was established in 2006 as part of the NitroEurope Integrated Project to infer reactive nitrogen (Nr) dry deposition fluxes, based on low-cost sampling of gaseous and aerosol species and inferential modelling. The network provides monthly measurements of NH3, NH4+, HNO3 and NO3−, as well as SO2, SO42−, HCl, Cl− and base cations at 58 sites. Measurements are made with an established low-cost denuder methodology (DELTA) as a basis to: (1) examine temporal trends and spatial patterns across Europe, (2) improve and calibrate inferential modelling techniques to estimate exchange of Nr species, (3) provide best estimates of atmospheric dry N deposition, and (4) permit an analysis of net GHG exchange in relation to atmospheric and agricultural N inputs at the European scale. Responsibility for measurements is shared among seven European laboratories. An inter-comparison of the DELTA implementation by 6 laboratories at 4 test sites (Montelibretti, Italy; Braunschweig, Germany; Paterna, Spain and Auchencorth, UK) from July to October 2006 provided training for the laboratories and showed that good agreement was achieved in different climatic conditions (87% of laboratory site-means within 20% of the inter-laboratory median). Results obtained from the first year of measurements show substantial spatial variability in atmospheric Nr concentrations, illustrating the major local (NH3) and regional (HNO3, NO3−, and NH4+) differences in Nr concentrations. These results provide the basis to develop future estimates of site-based Nr dry deposition fluxes across Europe, and highlight the role of NH3, largely of agricultural origin, which was the largest single constituent and will dominate dry Nr fluxes at most sites. 相似文献
107.
Peggy S. M. Hill 《Die Naturwissenschaften》2009,96(12):1355-1371
Animal communication is a dynamic field that promotes cross-disciplinary study of the complex mechanisms of sending and receiving
signals, the neurobiology of signal detection and processing, and the behaviors of animals creating and responding to encoded
messages. Alongside visual signals, songs, or pheromones exists another major communication channel that has been rather neglected
until recent decades: substrate-borne vibration. Vibrations carried in the substrate are considered to provide a very old
and apparently ubiquitous communication channel that is used alone or in combination with other information channels in multimodal
signaling. The substrate could be ‘the ground’, or a plant leaf or stem, or the surface of water, or a spider’s web, or a
honeybee’s honeycomb. Animals moving on these substrates typically create incidental vibrations that can alert others to their
presence. They also may use behaviors to create vibrational waves that are employed in the contexts of mate location and identification,
courtship and mating, maternal care and sibling interactions, predation, predator avoidance, foraging, and general recruitment
of family members to work. In fact, animals use substrate-borne vibrations to signal in the same contexts that they use vision,
hearing, touch, taste, or smell. Study of vibrational communication across animal taxa provides more than just a more complete
story. Communication through substrate-borne vibration has its own constraints and opportunities not found in other signaling
modalities. Here, I review the state of our understanding of information acquisition via substrate-borne vibrations with special
attention to the most recent literature. 相似文献
108.
Runoff and dissolved organic carbon loss from a paired-watershed study of three adjacent agricultural Watersheds 总被引:2,自引:0,他引:2
Kristen S. Veum Keith W. Goyne Peter P. Motavalli Ranjith P. Udawatta 《Agriculture, ecosystems & environment》2009,130(3-4):115-122
Organic matter plays several important roles in the biogeochemistry of terrestrial and aquatic ecosystems including the mobilization and transport of nutrients and pollutants. Cropping, tillage practices and vegetative buffer strip installation affect losses of dissolved organic carbon (DOC). While many studies show reductions in pollutant export from agroecosystems where vegetative buffers have been implemented, buffer strips may be a source of DOC and contribute to surface water pollution. Using a paired-watershed approach, the objectives of this study were to determine the effect of grass and agroforestry buffers on runoff and DOC loss, compare runoff and DOC losses between the growing and fallow seasons, and investigate crop effects on runoff and DOC losses. The study design consisted of three small agricultural Watersheds in a no-till, maize-soybean rotation located in the claypan region of northeast Missouri, USA; one watershed was planted with grass buffer strips, one with agroforestry buffer strips, and one unaltered watershed served as the control. Runoff and DOC loss were measured during a six-year calibration period (1991–1997) prior to buffer installation and for a nine-year treatment period (1997–2006). The grass buffer strips significantly decreased runoff by 8.4% (p = 0.015) during the treatment period while the agroforestry buffer system exhibited no significant change in runoff (p = 0.207). Loss of DOC was not significantly affected by grass or agroforestry buffer installation (p = 0.535 and p = 0.246, respectively). Additionally, no significant difference in runoff or DOC loss was found between crops (maize and soybean) or between seasons (growing and fallow). Overall, this study indicates that grass buffer systems are effective at reducing runoff and that DOC contamination of surface waters is not exacerbated by either type of vegetative buffer strip. 相似文献
109.
Thomas Merckx Ruth E. Feber Philip Riordan Martin C. Townsend Nigel A.D. Bourn Mark S. Parsons David W. Macdonald 《Agriculture, ecosystems & environment》2009,130(3-4):177-182
How best to optimize the biodiversity gain from agri-environment schemes (AES) has recently been identified as a key policy-relevant question. Here, the effects of two features of lowland agricultural landscapes on the abundance and diversity of larger moths are contrasted. Although both features bring about positive effects, hedgerow trees have a larger impact than 6 m wide grassy field margins. Whilst AES payments are given to create and maintain grass margins, no financial reward is currently offered for the retention of hedgerow trees. Furthermore, it was only in areas where the amount of land under AES was experimentally increased, by targeting farmers, that the presence of hedgerow trees resulted in a substantially higher abundance (+60%) and diversity (+38%) of moths. Thus, by using larger moths as bio-indicators of landscape-scale quality, it is demonstrated that improvements to the cost-effectiveness of AES could be achieved, firstly, by providing more appropriate financial rewards to farmers for different landscape features, and secondly, through landscape-scale targeting of farmers to encourage participation in AES. 相似文献
110.
N. L. Panwar N. S. Rathore 《Mitigation and Adaptation Strategies for Global Change》2009,14(8):711-720
Facing the finiteness of fossil fuels and its associated environmental problems, new prospects to cover energy demand are
urgently required. Energy from surplus biomass can support an essential contribution to a sustainable energy generation. This
paper deals with a case study of surplus biomass available in the Indian state Rajasthan. About 1275 MW electrical power is
possible to generate through biomass gasifier based power generation plant through surplus biomass available in Rajasthan.
About 1656 tonnes of CO2 can be saved annually by installation of 1 MW biomass gasifier based power plant. The techno economic parameter like net
present worth, cost benefit ratio and pay back period are also carried out for this route of power generation and these are
about 1.18 million US$, 1.42 and 8 years and 2 months respectively. 相似文献