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1.
Detection of hydA genes of Clostridia spp. using degenerative and species specific primers for C. butyricum were optimized by the addition of bovine serum albumin (BSA) to polymerase chain reaction (PCR) and quantitative PCR (qPCR) reactions. BSA concentrations ranging from 100 to 400 ng/μl were examined using pure cultures and a variety of environmental samples as test targets. A BSA concentration of 100 ng/μl, which is lower than previously reported in the literature, was found to be most effective in improving the detection limit. The brightness of amplicons with 100 ng/μl BSA increased in ethidium bromide-treated gels, the minimum detection limit with BSA was at least one log greater, and cycle threshold (C T) values were lower than without BSA in qPCR indicating improved detection of target deoxyribonucleic acid for most samples tested. Although amplicon visualization was improved at BSA concentrations greater than or equal to 100 ng/μl, gene copy numbers detected by qPCR were less, CT values were increased, and T m values were altered. SYBR Green dissociation curves of qPCR products of DNA from pure culture or sludge samples showed that BSA at 100 ng/μl reduced the variability of peak areas and T m values.  相似文献   

2.
Real-time polymerase chain reaction (PCR) is considered a highly sensitive method for the quantification of microbial organisms in environmental samples. This study was conducted to evaluate real-time PCR with SybrGreen detection as a quantification method for sulfate-reducing bacteria (SRB) in industrial wastewater produced by several chemical industries. We designed four sets of primers and developed standard curves based on genomic DNA of Desulfovibrio vulgaris from pure culture and on plasmids containing dissimilatory sulfate reductase (dsrA) or adenosine-5′-phosphosulfate reductase (apsA) genes of SRB. All the standard curves, two for dsrA and two for apsA genes, had a linear range between 0.95 × 102 and 9.5 × 106 copies/μL and between 1.2 × 103 and 1.2 × 107 copies/μL, respectively. The theoretical copy numbers of the tenfold dilutions of D. vulgaris genomic DNA were best estimated (between 2.7 to 10.5 times higher than theoretical numbers) by the standard curve with DSR1F and RH3-dsr-R primers. To mimic the effect of foreign DNA in environmental samples, serial dilutions of D. vulgaris genomic DNA were mixed with Escherichia coli chromosomal DNA (40 ng per assay). This influenced neither PCR amplification nor the quantification of target DNA. Industrial wastewater was sampled during a 15-month period and analyzed for the presence of SRB, based on dsrA gene amplification. SRB displayed a higher abundance during the summer (about 107–108 targets mL−1) and lower during the winter (about 104–105 targets mL−1). The results indicate that our real-time PCR approach can be used for detection of uncultured SRB and will provide valuable information related to the abundance of SRB in durable environmental samples, such as complex and saline industrial wastewaters.  相似文献   

3.
Allelic dropouts are an important source of genotyping error, particularly in studies using non-invasive sampling techniques. This has important implications for conservation biology, as an increasing number of studies are now using non-invasive techniques to study rare species or endangered populations. Previously, allelic dropout has typically been associated with PCR amplification of low quality/quantity template DNA. However, in this study we recorded high levels of allelic dropout (21–57%) at specific loci amplified from a high quality DNA (63.1 ± 7.8 ng/μl) source in the red fox (Vulpes vulpes). We designed a series of experiments to identify the sources of error. Whilst we were able to show that the best method to identify allelic dropout was the dilution of template DNA prior to PCR amplification, our data also showed two specific patterns: (1) allelic dropouts occurred at specific loci; (2) allelic dropouts occurred at specific pair-wise combinations of alleles. These patterns suggest that mechanisms other than low quantity template DNA are responsible for allelic dropout. Further research on the causes of these patterns in this and other studies would further our understanding of genotyping errors and would aid future studies where allelic dropout may be a serious issue.  相似文献   

4.
Conservation strategies for populations of woodland caribou Rangifer tarandus caribou frequently emphasize the importance of predator–prey relationships and the availability of lichen-rich late seral forests, yet the importance of summer diet and forage availability to woodland caribou survival is poorly understood. In a recent article, Wittmer et al. (Can J Zool 83:407–418, 2005b) concluded that woodland caribou in British Columbia were declining as a consequence of increased predation that was facilitated by habitat alteration. Their conclusion is consistent with the findings of other authors who have suggested that predation is the most important proximal factor limiting woodland caribou populations (Bergerud and Elliot in Can J Zool 64:1515–1529, 1986; Edmonds in Can J Zool 66:817–826, 1988; Rettie and Messier in Can J Zool 76:251–259, 1998; Hayes et al. in Wildl Monogr 152:1–35, 2003). Wittmer et al. (Can J Zool 83:407–418, 2005b) presented three alternative, contrasting hypotheses for caribou decline that differed in terms of predicted differences in instantaneous rates of increase, pregnancy rates, causes of mortality, and seasonal vulnerability to mortality (Table 1, p 258). These authors rejected the hypotheses that food or an interaction between food and predation was responsible for observed declines in caribou populations; however, the use of pregnancy rate, mortality season and cause of mortality to contrast the alternative hypotheses is problematic. We argue here that the data employed in their study were insufficient to properly evaluate a predation-sensitive foraging hypothesis for caribou decline. Empirical data on seasonal forage availability and quality and plane of nutrition of caribou would be required to test the competing hypotheses. We suggest that methodological limitations in studies of woodland caribou population dynamics prohibit proper evaluation of the mechanism of caribou population declines and fail to elucidate potential interactions between top-down and bottom-up effects on populations. An erratum to this article can be found at  相似文献   

5.
A disposable horseradish peroxidase (HRP)-based electrochemical genosensor was developed for chronoamperometric detection of single-stranded asymmetric lolB gene PCR amplicon (118 bp in length) of the food-borne pathogen, Vibrio cholerae. A two-step sandwich-type hybridization strategy using two specific probes was employed for specific detection of the target single-stranded DNA (ssDNA). The analytical performances of the detection platform have been evaluated using a synthetic ssDNA (ST3) which was identical to the target single-stranded amplicon and a total of 19 bacterial strains. Under optimal condition, ST3 was calibrated with a dynamic range of 0.4883–15.6250 nM. By coupling asymmetric PCR amplification, the probe-based electrochemical genosensor was highly specific to the target organism (100% specificity) and able to detect as little as 0.85 ng/μl of V. cholerae genomic DNA.  相似文献   

6.

Background

Non-invasively collected samples allow a variety of genetic studies on endangered and elusive species. However due to low amplification success and high genotyping error rates fewer samples can be identified up to the individual level. Number of PCRs needed to obtain reliable genotypes also noticeably increase.

Methods

We developed a quantitative PCR assay to measure and grade amplifiable nuclear DNA in feline faecal extracts. We determined DNA degradation in experimentally aged faecal samples and tested a suite of pre-PCR protocols to considerably improve DNA retrieval.

Results

Average DNA concentrations of Grade I, II and III extracts were 982pg/µl, 9.5pg/µl and 0.4pg/µl respectively. Nearly 10% of extracts had no amplifiable DNA. Microsatellite PCR success and allelic dropout rates were 92% and 1.5% in Grade I, 79% and 5% in Grade II, and 54% and 16% in Grade III respectively. Our results on experimentally aged faecal samples showed that ageing has a significant effect on quantity and quality of amplifiable DNA (p<0.001). Maximum DNA degradation occurs within 3 days of exposure to direct sunlight. DNA concentrations of Day 1 samples stored by ethanol and silica methods for a month varied significantly from fresh Day 1 extracts (p<0.1 and p<0.001). This difference was not significant when samples were preserved by two-step method (p>0.05). DNA concentrations of fresh tiger and leopard faecal extracts without addition of carrier RNA were 816.5pg/µl (±115.5) and 690.1pg/µl (±207.1), while concentrations with addition of carrier RNA were 49414.5pg/µl (±9370.6) and 20982.7pg/µl (±6835.8) respectively.

Conclusions

Our results indicate that carnivore faecal samples should be collected as freshly as possible, are better preserved by two-step method and should be extracted with addition of carrier RNA. We recommend quantification of template DNA as this facilitates several downstream protocols.  相似文献   

7.
Monitoring wildlife species by DNA identification of samples collected non-invasively is an important tool in conservation management. DNA identification of species from faecal (scat) samples is problematic due to the small quantities and poor quality of the DNA isolated from such samples. This study demonstrates the use of real-time PCR technology in the identification of red fox (Vulpes vulpes) and pine marten (Martes martes). It is shown that real-time PCR can be used to identify fox and pine marten by either melting curve analysis (Tm determination) with SYBR Green 1 detection or by the use of species specific fluorogenic probes. The technique is shown to work efficiently with scat DNA.  相似文献   

8.
This study was undertaken to develop a quantitative polymerase chain reaction assay that would improve the utility of PCR for detecting Haplosporidium nelsoni (MSX), a serious parasite of the eastern oyster Crassostrea virginica. A competitive PCR sequence was generated from the H. nelsoni small subunit ribosomal DNA fragment, originally described by Stokes and colleagues, that was amplified by the same PCR primers and had similar amplification performance. Assays performed using competitor dilutions ranging from 0.05 to 500 pg/μl DNA were used to test oyster samples designated using histological techniques as having ``light' or ``heavy' MSX infections. Visual diagnoses were confirmed equally well with three methods: densitometry of ethidium-bromide-stained agarose, densitometry of SYBRGreen-stained polyacrylamide gels, and analysis by GeneScan 3.0 of fluorescent products detected in ultrathin gels. Oysters diagnosed as negative for MSX tested as negative or light by PCR. Oysters with light MSX infections generally had less than 5 pg/μl infectious DNA. Oysters with heavy infections generally corresponded to 5 pg/μl or greater competitor dilutions. Received September 3, 1999; accepted March 3, 2000.  相似文献   

9.
Purpose of the present study was to evaluate antioxidant, antibacterial, antifungal, and antiviral activities of the petroleum ether, chloroform, ethyl acetate and methanol extracts as well as the alkaloid fraction of Lycopodium clavatum L. (LC) from Lycopodiaceae growing in Turkey. Antioxidant activity of the LC extracts was evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging method at 0.2 mg/ml using microplate-reader assay. Antiviral assessment of LC extracts was evaluated towards the DNA virus Herpes simplex (HSV) and the RNA virus Parainfluenza (PI-3) using Madin-Darby Bovine Kidney (MDBK) and Vero cell lines. Antibacterial and antifungal activities of the extracts were tested against standard and isolated strains of the following bacteria; Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis, Acinobacter baumannii, Klebsiella pneumoniae, Staphylococcus aureus, Bacillus subtilis as well as the fungi; Candida albicans and C. parapsilosis. All of the extracts possessed noteworthy activity against ATCC strain of S. aureus (4 μg/ml), while the LC extracts showed reasonable antifungal effect. On the other hand, we found that only the chloroform extract was active against HSV (16–8 μg/ml), while petroleum ether and alkaloid extracts inhibited potently PI-3 (16–4 μg/ml and 32–4 μg/ml, respectively). However, all of the extracts had insignificant antiradical effect on DPPH. In addition, we also analyzed the content of the alkaloid fraction of the plant by capillary gas chromatography-mass spectrometry (GC-MS) and identified lycopodine as the major alkaloid.  相似文献   

10.
Abstract: Genetic profiling using fecal samples collected noninvasively in the wild can provide managers with an alternative to live-trapping. However, before embarking on a large-scale survey, feasibility of this methodology should be assessed for the focal species. Costs associated with fecal genotyping can be high because of the need for multiple amplifications to prevent and detect errors. Assessing the relative amount of target DNA before genotyping means samples can be eliminated where error rates will be high or amplification success will be low, thereby reducing costs. We collected fecal samples from an endangered population of swift fox (Vulpes velox) and employed target-DNA quantification and a screening protocol to assess sample quality before genetic profiling. Quantification was critical in identifying samples of low quality (68%, <0.2 ng/μL). Comparison of the amplification, from a subset of loci in 25 samples that did not meet the screening criteria, confirmed the effectiveness of this method. The protocol, however, used a considerable amount of DNA, and an assessment of the locus and sample variability allowed us to refine it for future population surveys. Although we did not use <50% of the samples we collected, the remaining samples provided 36 unique genotypes, which corresponded to approximately 70% of animals estimated to be present in the study area. Although obtaining fecal DNA from small carnivores is challenging, our protocol, including the quantification and qualification of DNA, the selection of markers, and the use of postgenotyping analyses, such as DROPOUT, CAPWIRE, and geographic information, provides a more cost-effective way to produce reliable results. The method we have developed is an informative approach that wildlife managers can use to conduct population surveys where the collection of feces is possible without the need for live-trapping.  相似文献   

11.
In the present study, antiproliferative, apoptotic and especially neurotoxic effects of Caulerpa racemosa var. cylindracea dry and wet extracts on mouse neuroblastoma cell line, NA2B were investigated by neurotoxicity screening test (NST). C. racemosa var. cylindracea wet and dry extracts were obtained by methanol (MT) extraction. The effect of the extracts on viability and proliferation was measured by MTT. NA2B cells were induced to differentiate using 1 μM dcAMP and the amount of inhibition of growing neurites in different dilutions (50, 35, 25, 15, 10 and 5 μl/ml) by extracts was measured. The number of apoptotic cells was computed by TUNEL method using cells in culture. It was found that majority of the cells died with dry extract above the level of 15 μl/ml due to the MT effect. Below this level, on the other hand, presence of cell death and antiproliferative effect was noted due to the toxic effects of C. racemosa var. cylindracea which was independent of MT. In all doses of wet extracts, similar but less prominent dose-dependent effects were observed. Below the level of 15 μl/ml, mild toxic effect presented itself with neurite inhibition. In addition to the toxic, apoptotic and antiproliferative effects of C. racemosa var. cylindracea, its neurotoxic effects possessing property at low concentrations which manifesting itself by neurite inhibition was also showed. This species offers a potential for developing new drugs due to its antiproliferative, toxic and apoptotic effects. Nevertheless, its neurotoxic effect is a factor to be considered as multifunctional agents especially in neuronal metabolism.  相似文献   

12.
Rapid isolation of fungal genomic DNA suitable for long distance PCR   总被引:1,自引:0,他引:1  
A quick and reliable method for screening fungal transformants for specific genetic modifications is essential for many molecular applications. We have compared the applicability of a few rapid DNA extraction methods for Myrothecium and Aspergillus and tested the resulting DNA as to its suitability for PCR. For Myrothecium gramineum, the highest DNA concentration was obtained with the procedure described by N. Vanittanakom et al. (J Clin Microbiol 2002, 40: 1739–1742). For A. nidulans, concentrations higher than 100 ng/μl were reached with the glass bead, the LiCl, the boiling, the liquid N2 and the protoplast-based method. Samples of M. gramineum resulting from the boiling and the liquid N2 procedure were suitable for the amplification of fragments up to 2.3 kb. The direct use of mycelium from M. gramineum in the PCR tube can be employed for the reproducible amplification of fragments up to 1 kb. Amplification of fragments up to 4.3 kb requires the use of the Elongase Mix on samples extracted with the liquid N2 procedure.  相似文献   

13.
Improved and efficient methods were developed for isolating high quality DNA and RNA from different sources of Iranian Yew (Taxus baccata L.). The methods were based on CTAB extraction buffer added with high levels of polyvinylpyrrolidone (PVP) and β-mercaptoethanol to properly remove polysaccharides and prevent oxidation of phenolics. The pellets obtained by ethanol precipitation were washed only with Chloroform: isoamyl alcohol (24:1). So, we could successfully eliminate the dangerous phenol/chloroform extraction steps from the isolation procedure. Both spectrophotometric (A260/A280 and A260/A230 ratios) and agarose electrophoresis analysis of isolated nucleic acids (DNA and RNA) indicated good results. DNA with the average yield of 100–300 μg/g leaf and stem tissue and total RNA with an average yield of 20–30 μg/g cell culture and 80–100 μg/g leaf and stem tissue of Iranian yew could be obtained. Successful amplification of pam and pds by PCR and RT-PCR, showed the integrity of isolated DNA and RNA, respectively.  相似文献   

14.
The swift fox Vulpes velox Say, 1823, a small canid native to shortgrass prairie ecosystems of North America, has been the subject of enhanced conservation and research interest because of restricted distribution and low densities. Previous studies have described distributions of the species in the southern Great Plains, but data on density are required to evaluate indices of relative abundance and monitor population trends. We examined regressions of swift fox density (estimated by mark-recapture) on timed-track surveys, scat surveys, and catch-per-unit effort indices. Seventy-nine swift foxes (42 male, 37 female) were captured 151 times during 10 240 trapnights between May 2003 and December 2004 in the Panhandle of Oklahoma, USA. Density estimates, based on mark-recapture data from autumn 2004, were 0.08–0.44 foxes/km2. Survey indices explained 51 to 76% of the variation in estimates of fox density. Our study indicates that surveys of time-to-track encounters and scat deposition rates show promise in monitoring trends in population abundance over large areas.  相似文献   

15.
Procedure for the Agrobacterium tumefaciens mediated T-DNA delivery into the elite clone(s) of Eucalyptus tereticornis using leaf explants from microshoots has been developed. Amongst two strains of A. tumefaciens namely, EHA105 and LBA4404 (harbouring pBI121 plasmid), strain EHA105 was found to be more efficient. Pre-culturing of tissue (2 days) on medium supplemented with 100 μM acetosyringone, before bacterial infection significantly increased transient expression of reporter gene (GUS). Co-cultivation period of 2 days and a bacterial density of 0.8 OD600 resulted in higher transient GUS expression. Method of injury to tissue, presence of acetosyringone in co-cultivation medium and photoperiod during co-cultivation also influenced the expression of transient GUS activity. Amongst the three clones tested, maximum transient GUS activity was recorded in clone ‘CE2’ followed by clone ‘T1’. Regeneration of transformed shoots was achieved on modified Murashige and Skoog medium (potassium nitrate was replaced with 990 mg/l potassium sulphate and ammonium nitrate with 392 mg/l ammonium sulphate, and mesoinositol concentration was increased to 200 mg/l). Stable transformation was confirmed on the basis of GUS activity and PCR amplification of DNA fragments specific to uidA and nptII genes. The absence of bacteria in the stable transformed tissues was confirmed by PCR amplification of fragment specific to 16S rRNA of bacteria.  相似文献   

16.
The two-tank accelerator/aerator modification of activated sludge significantly increases the biodegradation of hydrocarbons requiring initial monooxygenation reactions, such as phenol and 2,4-dichlorophenol (DCP). The small accelerator tank has a controlled low dissolved oxygen (DO) concentration that can enrich the biomass in NADH + H+. It also has a very high specific growth rate (μacc) that up-regulates the biomass’s content of the monooxygenase enzyme. Here, we develop and test the ACCEL model, which quantifies all key phenomena taking place when the accelerator/aerator system is used to enhance biodegradation of hydrocarbons requiring initial monooxygenations. Monooxygenation kinetics follow a multiplicative relationship in which the organic substrates (phenol or DCP) and DO have separate Monod terms, while the biomass’s content of NADH + H+ has a first-order term. The monooxygenase enzyme has different affinities (K values) for phenol and DCP. The biomass’s NADH + H+ content is based on a proportioning of NAD(H) according to the relative rates of NADH + H+ sources and sinks. Biomass synthesis occurs simultaneously through utilization of acetate, phenol, and DCP, but each has its own true yield. The ACCEL model accurately simulates all trends for one-tank and two-tank experiments in which acetate, phenol, and DCP are biodegraded together. In particular, DCP removal is affected most by DOacc and the retention-time ratio, Θacctotal. Adding an accelerator tank dramatically increases DCP removal, and the best DCP removal occurs for 0.2 < DOacc < 0.5 mg/l and 0.08 < Θacctotal < 0.2. The rates of phenol and DCP utilization follow the multiplicative relationship with a maximum specific rate coefficient proportional to μacc. Finally, μacc increases rapidly for Θacctotal < 0.25, acetate removal in the accelerator fuels the high μacc, and the biomass’s NADH + H+ content increases very dramatically for DOacc < 0.25 mg/l.  相似文献   

17.
The red panda (Ailurus fulgens) is an endangered species distributed in the Himalaya and Hengduan Mountains and extremely difficult to monitor because it is elusive, wary and nocturnal. However, recent advances in noninvasive genetics are allowing conservationists to indirectly estimate population size of this animal. Here, we present a pilot study of individual identification of wild red pandas using DNA extracted from faeces. A chain of optimal steps in noninvasive studies were used to maximize genotyping success and minimize error rate across sampling, selection of microsatellite loci, DNA extraction and amplification and data checking. As a result, 18 individual red pandas were identified successfully from 33 faecal samples collected in the field using nine red panda-specific microsatellite loci with a low probability of identity of 1.249 × 10−3 for full siblings. Multiple methods of tracking genotyping error showed that the faecal genetic profiles possessed very few genotyping errors, with an overall error rate of 1.12 × 10−5. Our findings demonstrate the feasibility and reliability of using faeces as an effective source of DNA for estimating and monitoring wild red panda populations.  相似文献   

18.
Gong HZ  Ji R  Li YX  Zhang HY  Li B  Zhao Y  Sun L  Yu F  Yang J 《Mycopathologia》2009,167(1):31-36
Fumonisin B1 (FB1) is the most abundant of the fumonisin mycotoxins, mainly produced in maize by F. verticillioides and F. proliferatum. A total of 282 corn samples harvested in 2005 from six provinces, the main corn-producing areas of China, were analyzed for FB1 using high-performance liquid chromatography. All samples except one were (99.6%) positive for FB1 at levels varying from 3 to 71,121 ng/g with mean and median levels for all samples of 6,662 and 1,569 ng/g, respectively. During an analysis of the distribution pattern for FB1, it became apparent that 43.6% of tested samples had FB1 concentrations below 1,000 ng/g, while 25.2% contained in excess of 5,000 ng/g. The average exposure to FB1 (1.1 μg/kg body weight/day) is within the provisional maximum tolerable daily intake of 2 μg/kg body weight/day set by the Joint FAO/WHO Expert Committee on Food Additives.  相似文献   

19.
Noninvasive genetic sampling, or noninvasive DNA sampling (NDS), can be an effective monitoring approach for elusive, wide‐ranging species at low densities. However, few studies have attempted to maximize sampling efficiency. We present a model for combining sample accumulation and DNA degradation to identify the most efficient (i.e. minimal cost per successful sample) NDS temporal design for capture–recapture analyses. We use scat accumulation and faecal DNA degradation rates for two sympatric carnivores, kit fox (Vulpes macrotis) and coyote (Canis latrans) across two seasons (summer and winter) in Utah, USA, to demonstrate implementation of this approach. We estimated scat accumulation rates by clearing and surveying transects for scats. We evaluated mitochondrial (mtDNA) and nuclear (nDNA) DNA amplification success for faecal DNA samples under natural field conditions for 20 fresh scats/species/season from <1–112 days. Mean accumulation rates were nearly three times greater for coyotes (0.076 scats/km/day) than foxes (0.029 scats/km/day) across seasons. Across species and seasons, mtDNA amplification success was ≥95% through day 21. Fox nDNA amplification success was ≥70% through day 21 across seasons. Coyote nDNA success was ≥70% through day 21 in winter, but declined to <50% by day 7 in summer. We identified a common temporal sampling frame of approximately 14 days that allowed species to be monitored simultaneously, further reducing time, survey effort and costs. Our results suggest that when conducting repeated surveys for capture–recapture analyses, overall cost‐efficiency for NDS may be improved with a temporal design that balances field and laboratory costs along with deposition and degradation rates.  相似文献   

20.
This study investigated the epidemiological and ecological factors to assess the infection pressure of alveolar echinococcosis to human which are living in villages and small towns. Foxes and fox faeces were examined for Echinococcus multilocularis and foxes were observed by radio telemetry in Upper Bavaria, Germany. Forty-three percent of the village foxes (n = 65) had been infected with E. multilocularis. This prevalence rate did not differ significantly from the prevalence among rural foxes, which was 39% (n = 33; χ 2 = 0.12, df = 1, p = 0.727) determined by the intestinal scraping technique. PCR analyses of fox faeces showed a higher infection rate of 35% (n = 26) among rural foxes than among foxes in villages and small towns (26%, n = 69; χ 2 = 0.68, df = 1, p = 0.411). One quarter of the fox faecal samples come from private gardens of residents. The radio-tracking study on 17 foxes showed that foxes preferred the built-up area and grassland outside the villages. Village foxes concentrated their activity within a range of 500 m around the settlement. Sixty-four percent of all bearings for radio-tracked foxes showed positions in areas outside the town, and 36% of bearings were within the settlement. Village foxes, which are infected with E. multilocularis, are able to carry the parasite continuously into settlements and fox faeces present an immediate source of infection to humans, especially within their gardens. Therefore, foxes are responsible for environmental E. multilocularis egg contamination in the vicinity of humans, leading to an infection risk to inhabitants of villages and small towns.  相似文献   

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