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961.
Detection and Characterization of Hepatitis A Virus and Norovirus in Mussels from Galicia (NW Spain)
Shellfish are recognized as a potential vehicle of viral disease and despite the control measures for shellfish safety there is periodic emergence of viral outbreaks associated with shellfish consumption. In this study a total of 81 mussel samples from Ría do Burgo, A Coruña (NW Spain) were analysed. Samples were collected in seven different harvesting areas with the aim to establish a correlation between the prevalence of norovirus (NoV) and hepatitis A virus (HAV) in mussel samples and the water quality. In addition, the genogroup of the detected HAV and NoV strains was also determined. The HAV presence was detected in 18.5 % of the samples. Contamination levels for this virus ranged from 1.1 × 102 to 4.1 × 106 RNA copies/g digestive tissue. NoV were detected in 49.4 % of the cases reaching contamination levels from 5.9 × 103 to 1.6 × 109 RNA copies/g digestive tissue for NoV GI and from 6.1 × 103 to 5.4 × 106 RNA copies/g digestive tissue for NoV GII. The χ²-test showed no statistical correlation between the number of positive samples and the classification of molluscan harvesting area based on the E. coli number. All the detected HAV strains belong to genogroup IB. NoV strains were assigned to genotype I.4, II.4 and II.6. 相似文献
962.
We examined changes in morphological and genomic diversities of viruses by means of transmission electronic microscopy and pulsed field gel electrophoresis(PFGE) over a nine-month period(April–December 2005) at four different depths in the oligomesotrophic Lac Pavin. We found that the majority of viruses in this lake belonged to the family of Siphoviridae or were untailed, with capsid sizes ranging from 30 to 60 nm, and exhibited genome sizes ranging from 15 to 45 kb. On average, 12 different genotypes dominated each of the PFGE fingerprints. The highest genomic viral richness was recorded in summer(mean = 14 bands per PFGE fingerprint) and in the epilimnion(mean = 13 bands per PFGE fingerprint). Among the physico-chemical and biological variables considered, the availability of the hosts appeared to be the main factor regulating the variations in the viral diversity. 相似文献
963.
Stijn?GoolaertsEmail authorView authors OrcID profile Julien?Denayer Bernard?Mottequin 《Die Naturwissenschaften》2017,104(11-12):98
The taxonomic affinities of fossils from the Frasnian succession of Belgium previously described as phyllopod and phyllocarid crustacean shields are discussed. The rediscovery of the holotype of Ellipsocaris dewalquei, the type species of the genus Ellipsocaris Woodward in Dewalque, 1882, allows to end the discussion on the taxonomic assignation of the genus Ellipsocaris. It is removed from the phyllopod crustaceans as interpreted originally and considered here as an ammonoid anaptychus. Furthermore, it is considered to be a junior synonym of the genus Sidetes Giebel, 1847. Similarly, Van Straelen’s (1933) lower to middle Frasnian record Spathiocaris chagrinensis Ruedemann, 1916, is also an ammonoid anaptychus. Although ammonoids can be relatively frequent in some Frasnian horizons of Belgium, anaptychi remain particularly scarce and the attribution to the present material to peculiar ammonoid species is not possible. 相似文献
964.
Kirstin?Anderson?HansenEmail authorView authors OrcID profile Alyssa?Maxwell Ursula?Siebert Ole?N?sbye?Larsen Magnus?Wahlberg 《Die Naturwissenschaften》2017,104(5-6):45
In-air hearing in birds has been thoroughly investigated. Sound provides birds with auditory information for species and individual recognition from their complex vocalizations, as well as cues while foraging and for avoiding predators. Some 10% of existing species of birds obtain their food under the water surface. Whether some of these birds make use of acoustic cues while underwater is unknown. An interesting species in this respect is the great cormorant (Phalacrocorax carbo), being one of the most effective marine predators and relying on the aquatic environment for food year round. Here, its underwater hearing abilities were investigated using psychophysics, where the bird learned to detect the presence or absence of a tone while submerged. The greatest sensitivity was found at 2 kHz, with an underwater hearing threshold of 71 dB re 1 μPa rms. The great cormorant is better at hearing underwater than expected, and the hearing thresholds are comparable to seals and toothed whales in the frequency band 1–4 kHz. This opens up the possibility of cormorants and other aquatic birds having special adaptations for underwater hearing and making use of underwater acoustic cues from, e.g., conspecifics, their surroundings, as well as prey and predators. 相似文献
965.
Qian?Sun Kenneth?F.?Haynes Jordan?D.?Hampton Xuguo?ZhouEmail authorView authors OrcID profile 《Die Naturwissenschaften》2017,104(9-10):79
In social insects, the postembryonic development of individuals exhibits strong phenotypic plasticity in response to the environment, thus generating the caste system. Different from eusocial Hymenoptera, in which queens dominate reproduction and inhibit worker fertility, the primary reproductive caste in termites (kings and queens) can be replaced by neotenic reproductives derived from functionally sterile individuals. Feedback regulation of nestmate differentiation into reproductives has been suggested, but the sex specificity remains inconclusive. In the eastern subterranean termite, Reticulitermes flavipes, we tested the hypothesis that neotenic reproductives regulate worker-reproductive transition in a sex-specific manner. With this R. flavipes system, we demonstrate a sex-specific regulatory mechanism with both inhibitory and stimulatory functions. Neotenics inhibit workers of the same sex from differentiating into additional reproductives but stimulate workers of the opposite sex to undergo this transition. Furthermore, this process is not affected by the presence of soldiers. Our results highlight the reproductive plasticity of termites in response to social cues and provide insights into the regulation of reproductive division of labor in a hemimetabolous social insect. 相似文献
966.
Vázquez S Hevia A Moreno E Esteban E Peñalosa JM Carpena RO 《Journal of environmental management》2011,92(8):2069-2075
Non-amended soils affected by pyritic sludge residues were monitored for 7 years to assess the long-term natural attenuation ability of these soils. The decrease in both the total concentration of elements (particularly As) and (NH(4))(2)SO(4)-extractable fractions of Mn, and Zn, below the maximum permissible levels indicate a successful natural ability to attenuate soil pollution. Soil acidification by pyrite oxidation and rainfall-enhanced leaching were the largest contributors to the reduction of metals of high (Mn, Cu, Zn and Cd) and low (Fe, Al, and As) availability. Periodic use of correlation and spatial distribution analysis was useful in monitoring elemental dispersion and soil property/element relationships. 相似文献
967.
Alonso-Santurde R Andrés A Viguri JR Raimondo M Guarini G Zanelli C Dondi M 《Journal of environmental management》2011,92(3):994-1002
The feasibility of recycling spent foundry sand in clay bricks was assessed in laboratory, pilot line and industrial trials, using naturally occurring sand as a reference. Raw materials were analyzed by X-ray fluorescence, X-ray diffraction, particle size distribution, and leaching and combined to produce bodies containing up to 35% wt. sand. The extrusion, drying and firing behaviour (plasticity, drying sensitivity, mechanical strength, bulk density, water absorption, and shrinkage) were determined. The microstructure, phase composition, durability and leaching (EN 12457, granular materials, end-life step, European Waste Landfill Directive; NEN 7345, monolithic materials, use-life step, Dutch Building Material Decree) were evaluated for bricks manufactured at optimal firing temperature. These results demonstrate that spent foundry sand can be recycled in clay bricks. There are no relevant technological drawbacks, but the feasibility strongly depends on the properties of the raw materials. Spent foundry sand may be introduced into bricks up to 30% wt. Most of the hazardous elements from the spent foundry sand are inertized during firing and the concentrations of hazardous components in the leachates are below the standard threshold for inert waste category landfill excepting for chromium and lead; however, their environmental risk during their use-life step can be considered negligible. 相似文献
968.
Jesús M. Avilés Juan J. Soler Nathan S. Hart 《Behavioral ecology and sociobiology》2011,65(9):1721-1730
It has been proposed that the blue-green bird egg colourations of many avian species may constitute a sexually selected female
signal that males can use to modulate their parental investment. A fundamental untested assumption for the validation of this
hypothesis is that males can accurately assess differences in the colour of eggs. A recent review suggests that this could
be particularly problematic when egg clutches were located within a dimly lit nest cavity, due to limitations of the visual
system in low light conditions. Here, we first used a photoreceptor noise-limited model of colour discrimination ability that
accounts for visual performance under low light conditions to study whether a typical cavity-nesting passerine, the spotless
starling Sturnus unicolor, can discriminate their eggs under the ambient illumination in their nest-holes. Secondly, we tested the validity of model
predictions with behavioural data collected in two egg discrimination experiments performed in this species. Estimated egg
detectability depended entirely on model assumptions about visual limitations linked to light intensity. Starlings would not
be able to discriminate egg differences in their nests if the model was based on the assumption that light intensity limited
detectability, whereas they could potentially perceive as different many possible pairwise clutch comparisons if the model
assumption was that light intensity did not limit detectability. Results of behavioural experiments fitted the prediction
of the visual model where light intensity did not limit detectability. Our results suggest that photoreceptor noise-limited
colour models based on stimulation of single photoreceptors cannot, at present, be used to predict egg discrimination ability
in spotless starlings under low light conditions. Future studies aiming to test egg discrimination constraints in the frame
of the sexual selection hypothesis should therefore combine both modelling and behavioural experiments to determine which
are the components of the models that produce the mismatch with the behavioural conditions. 相似文献
969.
Paulina L. González-Gómez Natalia Ricote-Martinez Pablo Razeto-Barry Ivania S. Cotorás Francisco Bozinovic 《Behavioral ecology and sociobiology》2011,65(11):2141-2148
A common assumption in behavioral ecology is that the valuation of a resource by consumers depends on the energetic value
of the resource itself. Nevertheless, the value of a resource may be relative to the condition of the organism, which is in
turn related to the abiotic conditions such as ambient temperature. We developed a theoretical model—incorporating these untested
assumptions—to predict a functional relationship between territorial aggression and ambient temperature for individuals sensitive
to daily variations in energy availability. We evaluated our theoretical predictions against a field experiment carried out
with the hummingbird Sephanoides sephaniodes. The model predicted a quadratic relation between aggression intensity and ambient temperature. Field data were better explained
by a quadratic equation than a linear function, suggesting the existence of lower and upper thresholds of temperature which
determine the intensity of territorial defense. Ambient temperature affects energy expenditure for thermoregulation, and therefore,
it fixes the benefit level that must be produced by the territory to pay the costs of its defense. Our findings strongly suggest
that abiotic conditions can change an animal evaluation of the yield of a resource and in turn influence the behavioral strategy
which it adopts. 相似文献
970.
Poor-data and data-poor species stock assessment using a Bayesian hierarchical approach 总被引:4,自引:0,他引:4
Appropriate inference for stocks or species with low-quality data (poor data) or limited data (data poor) is extremely important. Hierarchical Bayesian methods are especially applicable to small-area, small-sample-size estimation problems because they allow poor-data species to borrow strength from species with good-quality data. We used a hammerhead shark complex as an example to investigate the advantages of using hierarchical Bayesian models in assessing the status of poor-data and data-poor exploited species. The hammerhead shark complex (Sphyrna spp.) along the Atlantic and Gulf of Mexico coasts of the United States is composed of three species: the scalloped hammerhead (S. lewini), the great hammerhead (S. mokarran), and the smooth hammerhead (S. zygaena) sharks. The scalloped hammerhead comprises 70-80% of the catch and has catch and relative abundance data of good quality, whereas great and smooth hammerheads have relative abundance indices that are both limited and of low quality presumably because of low stock density and limited sampling. Four hierarchical Bayesian state-space surplus production models were developed to simulate variability in population growth rates, carrying capacity, and catchability of the species. The results from the hierarchical Bayesian models were considerably more robust than those of the nonhierarchical models. The hierarchical Bayesian approach represents an intermediate strategy between traditional models that assume different population parameters for each species and those that assume all species share identical parameters. Use of the hierarchical Bayesian approach is suggested for future hammerhead shark stock assessments and for modeling fish complexes with species-specific data, because the poor-data species can borrow strength from the species with good data, making the estimation more stable and robust. 相似文献