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1.
Collembolans are known indicators of soil disturbance, used in several soil biodiversity monitoring programmes. As for other groups of soil microarthropods, taxonomic determination of Collembola species requires a huge effort and expert knowledge. In this study, we evaluated whether identification of Collembola species to the morphotype level, using an eco-morphological index which classifies individuals based on their adaptation to the soil, can be used as a surrogate of species richness in extensive monitoring schemes. The same evaluation was performed for higher taxa surrogates, using taxonomic categories at the genus and family levels. Additionally, sampling effort for perennial crops and forest systems was determined. Species data were collected from 35 sites sampled within different projects with the same number of samples (16 per site). Results showed that, on average, 8–12 samples are enough to have a good estimate of species richness for this type of systems, averaging 80–90%, but varying considerably with site habitat heterogeneity and local Collembola species pool. GLM models (using species richness as response variable) fitted for family, genus or morphotype levels (explanatory variables) were all significant (p < 0.05) but only the latter two had a pseudo R2 higher than 0.75. This indicates that when a rapid, cost-effective assessment of Collembola richness in different sites is required, this eco-morphological trait approach, as well as the determination to the genus level, could be used.  相似文献   

2.
Nitrogen fixation rates by epiphyllous microorganisms are affected by desiccation. Rates from leaf samples which had been dried for 12 h were 0.66 ng N/10 cm2/h. In contrast, rates from leaves which had been kept continuously wet were 18.69 ng N/10 cm2/h. Leaf samples which had been rehydrated for 2 and 4 h showed intermediate fixation rates (4.26 and 9.76 ng N/10 cm2/h, respectively). Epiphyllous bryophytes maintain moist conditions on the leaf surface and thus create a microenvironment suitable for prolonged fixation by the microorganisms.  相似文献   

3.
Seasonal fluctuations of soil and litter microarthropod populations in a pine,Pinus kesiya Royle plantation of North Eastern India were investigated between November 1976 and November 1977. Three major groups were recognized: (a) Collembola, (b) Acarina and (c) miscellaneous. Collembola was the most abundant group and was dominated byIsotoma trispinata (MacGillivray). The total microarthropod density ranged from 26,800 per m2 to 145,200 per m2. Collembola densities ranged from 10,000 to 121,200 per m2, Acarina densities ranged from 8,800 to 41,600 per m2, and the miscellaneous group ranged from 1,200 to 6,400 per m2. Soil moisture was positively correlated with total arthropod, Collembola and Acarina densities. Soil temperature was positively correlated only with Acarina. Densities of Collembola and Acarina were negatively correlated.The work described in this paper was carried out while the author was at the Department of Zoology, North Eastern Hill University, Shillong, Mehgalaya (India).It was presented at the Ninth International Biometeorological Congress, 23rd Sptember–1st October, 1981, Osnabrück and Stuttgart-Hohenheim, FRG.  相似文献   

4.
Tiunov AV  Scheu S 《Oecologia》2005,142(4):636-642
The functioning of the plant-mycorrhiza system depends on interactions with other organisms, including saprotrophic (ST) soil fungi. The interactions between mycorrhizal and ST fungi are likely affected by fungivorous soil animals, such as Collembola. In a two-factorial laboratory experiment lasting for 30 weeks we assessed the effects of an arbuscular mycorrhizal fungus (Glomus mosseae) and Collembola (Protaphorura fimata, Heteromurus nitidus and Folsomia candida) on the community composition of ST microfungi in soil planted with the invasive grass Cynodon dactylon. The presence of mycorrhiza substantially reduced total plant biomass and reduced N and P availability to the soil microflora, though these effects were less pronounced in the presence of Collembola. The density of Collembola was high (corresponding to about 2×105 individuals m–2) and was not affected by the presence of G. mosseae. In spite of the large amount of mycorrhizal mycelium in soil, it contributed little to Collembola nutrition. The presence of mycorrhiza strongly affected the community structure of ST soil fungi. In particular, mycorrhiza reduced the relative abundance of Trichoderma harzianum and Exophiala sp., but increased the abundance of Ramichloridium schulzeri and several sterile forms. However, the difference between fungal communities in mycorrhizal and non-mycorrhizal treatments was much more pronounced in the presence of Collembola. Presumably, the intense grazing by Collembola destabilized the ST fungal community, thereby making it more susceptible to the influence of G. mosseae. These results document for the first time that fungal feeding soil invertebrates can significantly affect the interactions between mycorrhizal fungi and ST soil microorganisms.  相似文献   

5.
Inanimate surfaces are regarded as key vehicles for the spread of human norovirus during outbreaks. ISO method 15216 involves the use of cotton swabs for environmental sampling from food surfaces and fomites for the detection of norovirus genogroup I (GI) and GII. We evaluated the effects of the virus drying time (1, 8, 24, or 48 h), swab material (cotton, polyester, rayon, macrofoam, or an antistatic wipe), surface (stainless steel or a toilet seat), and area of the swabbed surface (25.8 cm2 to 645.0 cm2) on the recovery of human norovirus. Macrofoam swabs produced the highest rate of recovery of norovirus from surfaces as large as 645 cm2. The rates of recovery ranged from 2.2 to 36.0% for virus seeded on stainless-steel coupons (645.0 cm2) to 1.2 to 33.6% for toilet seat surfaces (700 cm2), with detection limits of 3.5 log10 and 4.0 log10 RNA copies. We used macrofoam swabs to collect environmental samples from several case cabins and common areas of a cruise ship where passengers had reported viral gastroenteritis symptoms. Seventeen (18.5%) of 92 samples tested positive for norovirus GII, and 4 samples could be sequenced and had identical GII.1 sequences. The viral loads of the swab samples from the cabins of the sick passengers ranged from 80 to 31,217 RNA copies, compared with 16 to 113 RNA copies for swab samples from public spaces. In conclusion, our swab protocol for norovirus may be a useful tool for outbreak investigations when no clinical samples are available to confirm the etiology.  相似文献   

6.
In previous studies workers determined that two lactic acid bacterium isolates, Lactococcus lactis subsp. lactis C-1-92 and Enterococcus durans 152 (competitive-exclusion bacteria [CE]), which were originally obtained from biofilms in floor drains, are bactericidal to Listeria monocytogenes or inhibit the growth of L. monocytogenes both in vitro and in biofilms at 4 to 37°C. We evaluated the efficacy of these isolates for reducing Listeria spp. contamination of floor drains of a plant in which fresh poultry is processed. Baseline assays revealed that the mean numbers of Listeria sp. cells in floor drains sampled on six different dates (at approximately biweekly intervals) were 7.5 log10 CFU/100 cm2 for drain 8, 4.9 log10 CFU/100 cm2 for drain 3, 4.4 log10 CFU/100 cm2 for drain 2, 4.1 log10 CFU/100 cm2 for drain 4, 3.7 log10 CFU/100 cm2 for drain 1, and 3.6 log10 CFU/100 cm2 for drain 6. The drains were then treated with 107 CE/ml in an enzyme-foam-based cleaning agent four times in 1 week and twice a week for the following 3 weeks. In samples collected 1 week after CE treatments were applied Listeria sp. cells were not detectable (samples were negative as determined by selective enrichment culture) for drains 4 and 6 (reductions of 4.1 and 3.6 log10 CFU/100 cm2, respectively), and the mean numbers of Listeria sp. cells were 3.7 log10 CFU/100 cm2 for drain 8 (a reduction of 3.8 log10 CFU/100 cm2), <1.7 log10 CFU/100 cm2 for drain 1 (detectable only by selective enrichment culture; a reduction of 3.3 log10 CFU/100 cm2), and 2.6 log10 CFU/100 cm2 for drain 3 (a reduction of 2.3 log10 CFU/100 cm2). However, the aerobic plate counts for samples collected from floor drains before, during, and after CE treatment remained approximately the same. The results indicate that application of the two CE can greatly reduce the number of Listeria sp. cells in floor drains at 3 to 26°C in a facility in which fresh poultry is processed.  相似文献   

7.
Biofilm formation on stainless steel samples immersed in cooling water has been evaluated by exposing metal samples to cooling seawater for 30 days. Anaerobic bacteria were then at 1.6 × 106/cm2, with sulphate-reducing species predominating. Aerobic bacteria and fungi were 2600 and 140/cm2, respectively. After 60 days, numbers of aerobic microorganisms remained constant whereas the count of anaerobic microorganisms had increased to 1.8×109/cm2. Scanning electron microscopy showed the presence of morphologically different microorganisms in deposits and as a mucilaginous net. No signs of corrosion were detected on the stainless steel surface.The authors are with the Departamento de Engenharia Bioquimica Centro de Tecnologia, Bloco E. Universidade Federal do Rio de Janeiro Ilha do Fundão, 21941-900 Rio de Janeiro, Brazil  相似文献   

8.
Synopsis

The time evolution of the A-to-B transition has been monitored by Raman spectroscopy and found to vary significantly for different samples. Though all samples were prepared in the identical fashion, some samples completed the transition on the time scale of several hours while other samples took days. The shortest time required for the A conformation to disappear was about 2 hours, as determined by the disappearance of the A-form Raman band at 807 cm?1. For these fastest transforming samples, the B-form Raman band at 835 cm?1 was clearly evident after about 5 hours. These data are consistent with the hypothesis that the A conformation of DNA is stabilized by intermolecular interactions.  相似文献   

9.
Abstract 1. Temperate woodland Collembola feed predominantly on plant detritus and fungi. They exhibit preferences for different fungi reflecting resource value in terms of Collembola growth and reproduction. 2. Studies of fungal grazing by Collembola have focused on non‐interacting fungi and have used one genetic isolate as representative of an entire fungal species. This study examines the effects of fungal interactions on Collembola behaviour, and elucidates differences arising from the use of genetically distinct fungal isolates. 3. Folsomia candida were added to microcosms in which paired combinations of the fungi, Hypholoma fasciculare (four isolates), Phallus impudicus, Phanerochetae velutina and Resinicium bicolor (two isolates), were interacting. Collembola movement and mortality was recorded for 26 days. A constant preference for one fungal mycelium over the other was shown by Collembola in 12 of the 36 interactions studied. Lowest Collembola mortality was normally recorded on the preferred mycelium. 4. In 11 of the remaining 24 interactions, Collembola preference switched from one mycelium to the other; the greatest number of dead Collembola was recorded on the final preference. 5. Collembola behaviour on different fungal isolates was broadly similar, although in one species’ combination a change in fungal isolate resulted in a total reversal of Collembola preference. The implications of these results for decomposer food webs are considered.  相似文献   

10.
Pollen transport into houses via clothing was studied on different types of fabrics after clothing was aired or worn outdoors. After walking through grassland, 68 pollen grains/cm2 were found on clothes (tape samples). The amount of grass pollen, and especially pollen from insect-pollinated plants, increased from the shirt towards the shoes. The amount of pollen on clothes aired outdoors in a yard depended on the concentration in the ambient air and the texture of the fabrics. On vacuumed samples, 1.2 grains/cm2/h adhered to the furry fabric of fleece and wool, whereas only 0.3 grains/cm2/h adhered to a tight weave polyamide coat and a denim jacket. A moist cotton shirt gave slightly higher pollen counts in both the tape (8.6 grains/cm2/h) and the vacuumed samples (1.0 grains/cm2/h) compared to a dry shirt (5.6 and 0.6 grains/cm2/h), but the difference was not significant. Tape samples gave tenfold higher pollen numbers compared to vacuumed samples, probably due to the more optimal location of the tape sampling area on top of the shoulders. We conclude that clothing constitutes an important route for carrying allergenic pollen into houses. Pollen transport can be decreased by shaking outdoor clothing before entering a residence. In our case, shaking removed 68% pollen grains from trousers.  相似文献   

11.
Interventional cardiac procedures may be associated with high patient doses and therefore require special attention to protect the patients from radiation injuries such as skin erythema, cardiovascular tissue reactions or radiation-induced cancer. In this study, patient exposure data is collected from 13 countries (37 clinics and nearly 50 interventional rooms) and for 10 different procedures. Dose data was collected from a total of 14,922 interventional cardiology procedures. Based on these data European diagnostic reference levels (DRL) for air kerma-area product are suggested for coronary angiography (CA, DRL = 35 Gy cm2), percutaneous coronary intervention (PCI, 85 Gy cm2), transcatheter aortic valve implantation (TAVI, 130 Gy cm2), electrophysiological procedures (12 Gy cm2) and pacemaker implantations. Pacemaker implantations were further divided into single-chamber (2.5 Gy cm2) and dual chamber (3.5 Gy cm2) procedures and implantations of cardiac resynchronization therapy pacemaker (18 Gy cm2). Results show that relatively new techniques such as TAVI and treatment of chronic total occlusion (CTO) often produce relatively high doses, and thus emphasises the need for use of an optimization tool such as DRL to assist in reducing patient exposure. The generic DRL presented here facilitate comparison of patient exposure in interventional cardiology.  相似文献   

12.
Structure and density of soil microarthropod communities (Oribatida and Collembola) were studied in one natural beech forest and one spruce monoculture planted on a former beech stand in South Bohemia (Czech Republic). The spruce monoculture establishment increased microarthropod densities (93,000 ind. m?2 in the natural beech forest vs. 400,540 ind. m?2 in the spruce monoculture for Oribatida; 66,360 ind. m?2 in the natural beech forest vs. 136,360 ind. m?2 in the spruce monoculture for Collembola); additionally, it changed greatly the community structure in terms of species composition and functional traits. In the spruce monoculture, groups susceptible to disturbance were suppressed. The oribatid trophic structure changed as well with opportunistic herbifungivorous species increasing in the monoculture at the expense of fungivorous species. Similarly, hemiedaphic collembolans increased in the monoculture at the expense of euedaphic species. We conclude that the “functional approach” seems to be fruitful in revealing soil fauna response to environmental change.  相似文献   

13.
The heat shock protein Hsp70 has been shown to be a promising biomarker in aquatic and terrestrial organisms. However, its analysis in the soil insect Folsomia candida (Collembola) poses many problems as the protein is particularly unstable in this species. Western blotting has shown that the principal degradation fragment has a size of 48 kDa. We have developed a Western blot method that avoids the degradation of Hsp70 and was successful in detecting the protein in the springtail F. candida after a heat shock (12, 18 and 24 h at 32°C). In the second part of the study the organisms were exposed to artificial compressed soil contaminated with the dinitrophenol dinoseb (10, 15 and 20 μg g-1 dry weight [DW]). Hsp70 was analysed in pooled samples (40 to 150 collembola according to age) after 1, 2, 3, 4, 5, 6, 7, 11 and 14 days. The only significant induction was observed after 5 days at 20 μg g-1 DW of dinoseb. The induction patterns over time were dissimilar for the different concentrations and a relatively high variability between the replicates was observed. Our results show that we must be cautious when interpreting biomarker results, especially those for Hsp70.  相似文献   

14.
Printed batteries are an emerging solution for integrated energy storage using low‐cost, high accuracy fabrication techniques. While several printed batteries have been previously shown, few have designed a battery that can be incorporated into an integrated device. Specifically, a fully printed battery with a small active electrode area (<1 cm2) achieving high areal capacities (>10 mAh cm?2) at high current densities (1–10 mA cm?2) has not been demonstrated, which represents the minimum form‐factor and performance requirements for many low‐power device applications. This work addresses these challenges by investigating the scaling limits of a fully printed Zn–Ag2O battery and determining the electrochemical limitations for a mm2‐scale battery. Processed entirely in air, Zn–Ag2O batteries are well suited for integration in typical semiconductor packaging flows compared to lithium‐based chemistries. Printed cells with electrodes as small as 1 mm2 maintain steady operating voltages above (>1.4 V) at high current densities (1–12 mA cm?2) and achieve the highest reported areal capacity for a fully printed battery at 11 mAh cm?2. The findings represent the first demonstration of a small, packaged, fully printed Zn–Ag2O battery with high areal capacities at high current densities, a crucial step toward realizing chip‐scale energy storage for integrated electronic systems.  相似文献   

15.
C3H/HeA mice with high incidence of spontaneous breast cancer and Balb/c mice treated with 3,4-benzopyrene (BP) (by painting of the skin resulting in the development of skin cancer) were irradiated with 2,450-MHz microwaves (MW) in an anechoic chamber at 5 or 15 mW/cm2 (2 h daily, 6 sessions per week). C3H/HeA mice were irradiated from the 6th week of life, up to the 12th month of life. Balb/c mice treated with BP were irradiated either prior to (over 1 or 3 months) or simultaneously with BP treatment (over 5 months). The appearance of palpable tumors in C3H/HeA mice and of skin cancer in BP-treated Balb/c mice was checked every 2 weeks for 12 months. Two additional groups of mice were exposed to chronic stress caused by confinement or to sham-irradiation in an anechoic chamber; these served as controls. Irradiation with MWs at either 5 or 15 mW/cm2 for 3 months resulted in a significant lowering of natural antineoplastic resistance (mean number of lung neoplastic colonies was 2.8 ± 1.6 (SD) in controls, 6.1 ± 1.8 in mice exposed at 5 mW/cm2 and 10.8 ± 2.1 in those irradiated at 15 mW/cm2) and acceleration of development of BP-induced skin cancer (285 days in controls, 230 days for 5 mW/cm2 and 160 days for 15 mW/cm2). Microwave-exposed C3H/HeA mice developed breast tumors earlier than controls (322 days in controls, 261 days for 5 mW/cm2 and 219 days for 15 mW/cm2). A similar acceleration was observed in the development of BP-induced skin cancer in mice exposed simultaneously to BP and MWs (285 days in controls, 220 day for 5 mW/cm2 and 121 days for 15 mW/cm2). The acceleration of cancer development in all tested systems and lowering of natural antineoplastic resistance was similar in mice exposed to MW at 5 mW/cm2 or to chronic stress caused by confinement but differed significantly from the data obtained on animals exposed at 15 mW/cm2, where local thermal effects (“hot” spots) were possible.  相似文献   

16.
Although avoidance behavior is thought to be one of the major strategies for arthropods to cope with cold, there is a general lack of data supporting its use. This study tested the suggestion that Collembola migrate deeper into the soil to avoid cooling temperatures during the transition from summer to winter. We released mature hemi‐edaphic Folsomia candida Willem (Collembola: Isotomidae) in large (5 301 cm3) and small (306 cm3) soil microcosms exposed to ambient temperatures ranging between 5 and 20 °C. Springtails released in the large microcosms for periods of 2, 3, and 4 weeks dispersed throughout the soil column but remained more abundant in the upper third layer of the soil column whether exposed to weekly decreasing temperatures or a constant ambient temperature of 20 °C. Both small (juvenile) and large (mature) springtails exposed to cooling were more abundant in the upper third than in the middle or lower third of the soil columns after 2, 3, or 4 weeks. Groups of F. candida released in small microcosms provided with a positive soil temperature gradient displayed the same vertical distribution, with 90% of individuals clustered in the top 4.5 cm of the 15‐cm column whether exposed to air temperatures of 5, 10, 15, or 20 °C. Results from the two types of microcosms demonstrated that the vertical distribution of springtails remains strongly biased to the upper soil layer regardless of the temperature of their environment and whether the temperature in the soil column was uniform or graduated. This supports our prediction that hemi‐edaphic species such as F. candida do not relocate to warmer deeper soil layers, but tend to remain in the surface soil layer where they can acclimate to the cooling temperature.  相似文献   

17.
Air ions of both polarity, produced by corona electrodes, were used to evaporate to dryness liquid samples of ethyl alcohol (EA), water (W), and carbon tetrachloride (CTC). Drying times were determined with a beta-ray gauge. Ion exposed samples of EA, W, and CTC dried, respectively, 2.3, 3.2, and 5.4 times faster than the corresponding control samples when exposed simultaneously to 0.94×1012 positive and 1.83×1012 negative air ions cm–2s–1 under the same laboratory conditions. Drying by corona discharge could be explained by three different mechanisms. Electric wind caused by the ionic drag is proposed as the principal driving force for the observed enhancement of evaporation. The decrease in free energy of a dielectric in the presence of an electric field compared to its absence may have increased the escaping tendency of the molecules of the treated liquids. The turbulence in the liquids created by the rotational effect on the dielectric molecules by the electric field may also be a factor in further enhancing the mass transfer rates from the samples.  相似文献   

18.
Microbial solubilization of coal has been considered as a promising technology to convert raw coal into valuable products. In the present study, initially a total of 50 different aerobic bacterial and fungal isolates have been isolated from soil, coal and water samples of Dulmial Coal Mines, Chakwal, Pakistan, but on the basis of solubilization potential, only four isolates were selected for further study. The intensity of biosolubilization was measured by determining the weight loss of the coal pieces, which was observed to be about 25.93% by Pseudomonas sp. AY2, 36.36% by Bacillus sp. AY3 and 50% by Trichoderma sp. AY6, while Phanerochaete sp. AY5 showed maximum coal solubilization potential i.e. 66.67% in 30 days. UV/Vis spectrum revealed an increase in the pattern of absorbance of all treated samples compared to control referring to solubilization. Fourier transform infrared spectroscopy indicated alterations in the structure of treated coal in comparison to control coal suggesting breakdown in the complex structure of coal. The major absorbance bands in infrared spectroscopy for solubilization product were attributed to carbonyl (1,600 cm?1), hydroxyl (3,450 cm?1), cyclane (2,925 cm?1), ether linkage (1,000–1,300 cm?1), carboxyl (3,300–2,500 cm?1) and side chains of aromatic ring (1,000–500 cm?1). The presence of microorganisms and surface erosion of coal residues compared to control samples were observed by scanning electron microscopy, which suggested that isolated microorganisms were able to survive in coal for a longer period of time. Therefore, the present study concluded that microorganisms isolated from coal mines have excellent potential for coal solubilization which is considered as a crucial step in coal methanogenesis allowing them to be used successfully for in situ methane production to meet future energy demands.  相似文献   

19.
Summary Previous research by many investigators has demonstrated food limitation in both web-building and wandering spiders. Field experiments have tested for exploitative competition for prey in web-building, but not wandering species. As a first step to examining the question of whether spiders without webs exhibit exploitative competition, we manipulated densities of young stages of a common wolf spider, Schizocos ocreata, and measured (1) spider growth rate and (2) numbers of Collembola, a potential prey organism. Replicate populations of recently hatched S. ocreata were established in 1-m2 fenced plots at four levels: 0×, 0.25×, 1× and 4× natural density. Increasing spider density had a negative effect on spider growth rate, defined as increase in weight or cephalothorax width. Early in the experiment spider density had a weak negative effect on Collembola numbers [p(F)=0.08]. Taken together, this probable response by Collembola and the clear effect of spider density on growth rate constitute the first experimental evidence of intraspecific exploitative competition for prey in a species of wandering spider. We discuss (1) the strength of this evidence given the constraints of the experiment's design, and (2) the implications of the strong convergence in spider densities that had occurred after 2.5 months.  相似文献   

20.
《Endocrine practice》2007,13(5):458-462
ObjectiveTo report the outcomes of tumor-induced osteomalacia after treatment, particularly related to recovery of bone mass.MethodsWe review the clinical course of a 61-year-old man extremely debilitated from multiple fractures and neuromuscular weakness due to tumor-induced osteomalacia and report the changes in biochemical markers and bone density after removal of the causative neoplasm.ResultsAt the time of diagnosis, the patient’s serum phosphorus and 1,25 dihydroxyvitamin D levels were depressed, and his fibroblast growth factor-23 level was markedly elevated. These values normalized 2 days after surgery and remained within their respective reference ranges 4 and 12 months after resection of a mesenchymal tumor. Lumbar bone density values (T-scores) were 0.445 g/cm2 (-5.9) preoperatively, 0.939 g/cm2 (–1.4) 4 months after surgery, and 1.152 g/cm2 (0.7) 12 months after surgery. Left femoral neck values at the same time points were 0.525 g/cm2 (-3.0), 1.035 g/cm2 (-0.8), and 1.184 g/cm2 (1.9). Ultra-distal radius values at the same time points were 0.128 g/cm2 (-7.0), 0.191 g/cm2 (-5.9), and 0.259 g/cm2 (-4.8). In addition, he recovered neuromuscular function and was able to leave his wheelchair.ConclusionTumor-induced osteomalacia can be an extremely debilitating disease. With successful localization, identification, and resection of the neoplasm, bone mass and physical function can recover. (Endocr Pract. 2007;13:458-462)  相似文献   

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