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1.
We have investigated the influence on longevity and fecundity of Flavescence dorée phytoplasma (FDP), the agent of a grapevine yellows disease, in the experimental vector Euscelidius variegatus Kirschbaum. Late instar nymphs were exposed to one or the other of two strains of FDP (FD92 and FD2000) by feeding on infected broad bean (Vicia faba L.) or on healthy broad bean or maize (Zea mays L.) for an acquisition access period of 13 days. Detection of FDP in individual insects was done with PCR assays and revealed that almost all exposed leafhoppers had acquired FDP, for both FD92 and FD2000 strains. FDP infection significantly reduced the life span of males and females (ANOVA of the quartiles of survival distribution and Weibull scale parameter). FDP-exposed females produced significantly fewer nymphs. The two FDP strains had similar effects on reduction of survival and fecundity of leafhoppers. There was no significant differences in longevity of E. variegatus males exposed to FD broad bean than held on healthy broad bean or maize, but female survival and fecundity were reduced when they fed on maize versus healthy broad bean. 相似文献
2.
3.
Response of the Vitis vinifera L. cv. 'Nebbiolo' proteome to Flavescence dorée phytoplasma infection
Flavescence dorée is a serious phytoplasma disease affecting grapevine in several European countries. We studied the interaction of Flavescence dorée phytoplasma with its natural plant host by monitoring the effects of infection on the protein expression profile. Among the 576 analyzed spots, 33 proteins were differentially regulated in infected grapevines. Grouping into MIPS functional categories showed proteins involved in metabolism (21%), energy processes (9%), protein synthesis (3%), protein fate (18%), cellular transport and transport routes (6%), cell defense and virulence (42%). Among the differentially regulated proteins, we selected six targets (thaumatin I, thaumatin II, osmotin-like protein, plant basic secretory protein, AAA(+) Rubisco activase and proteasome α5 subunit) and we analyzed their expression by quantitative RT-PCR on samples collected in 2008 and 2009 in several vineyards in Piedmont region, Italy. There was a positive correlation between mRNA and protein expression for most of the genes in both the years. We discuss the involvement of these proteins in the specific response to phytoplasma infection. To our knowledge, this work is the first to investigate the response of the grapevine proteome to Flavescence dorée phytoplasma infection, and provides reference protein profiles for future comparative proteomic and genomic studies. 相似文献
4.
V. Trivellone M. Ripamonti E. Angelini L. Filippin M. Rossi C. Marzachí L. Galetto 《Journal of applied microbiology》2019,127(6):1801-1813
5.
F. Martinelli R. Scalenghe P. Marino A. A. Aksenov A. Pasamontes 《Plant biosystems》2016,150(1):43-53
Flavescence dorée (FD) is one of the most widely known grapevine yellows disease and one of the most unabated worldwide in the viticulture sector. In this paper, we outline a strategy for developing an integrated system of technologies to enable rapid, early disease FD detection and diagnosis. We propose the deployment of a newly developed sensor device, the differential mobility spectrometer (DMS), which has shown positive results with a similar vector-borne disease in Citrus. We have previously demonstrated that the gas chromatograph DMS (GC/DMS) can distinguish various citrus diseases, and the system may also allow detection of volatile organic compound (VOC) signals from a tree of other plant systems of unknown health status. This would be achieved by comparing it with the expected VOC profile analysis of healthy or infected trees for health status determination. We can map regions in the GC/DMS signal to gas chromatography mass spectrometry data, thus allowing for deconvolution of specific GC/DMS signatures. We showed that RNA-seq will allow identifying genes involved in volatile pathways (terpenoids, phenylpropanoids, and mevalonate pathways) and could be used to guide the DMS use for the discovery of new biomarkers. 相似文献
6.
Arnaud G Malembic-Maher S Salar P Bonnet P Maixner M Marcone C Boudon-Padieu E Foissac X 《Applied and environmental microbiology》2007,73(12):4001-4010
Vineyards of southern France and northern Italy are affected by the flavescence dorée (FD) phytoplasma, a quarantine pathogen transmitted by the leafhopper of Nearctic origin Scaphoideus titanus. To better trace propagation of FD strains and identify possible passage between the vineyard and wild plant compartments, molecular typing of phytoplasma strains was applied. The sequences of the two genetic loci map and uvrB-degV, along with the sequence of the secY gene, were determined among a collection of FD and FD-related phytoplasmas infecting grapevine, alder, elm, blackberry, and Spanish broom in Europe. Sequence comparisons and phylogenetic analyses consistently indicated the existence of three FD phytoplasma strain clusters. Strain cluster FD1 (comprising isolate FD70) displayed low variability and represented 17% of the disease cases in the French vineyard, with a higher incidence of the cases in southwestern France. Strain cluster FD2 (comprising isolates FD92 and FD-D) displayed no variability and was detected both in France (83% of the cases) and in Italy, whereas the more-variable strain cluster FD3 (comprising isolate FD-C) was detected only in Italy. The clonal property of FD2 and its wide distribution are consistent with diffusion through propagation of infected-plant material. German Palatinate grapevine yellows phytoplasmas (PGY) appeared variable and were often related to some of the alder phytoplasmas (AldY) detected in Italy and France. Finally, phylogenetic analyses concluded that FD, PGY, and AldY were members of the same phylogenetic subclade, which may have originated in Europe. 相似文献
7.
Attilio Rizzoli Elena Belgeri Mauro Jermini Marco Conedera Luisa Filippin Elisa Angelini 《Journal of Applied Entomology》2021,145(10):1015-1028
Flavescence dorée (FD) is a grapevine disease caused by associated phytoplasmas (FDp) which are epidemically spread by their main vector Scaphoideus titanus. The possible roles of alternative and secondary FDp plant hosts and vectors have gained interest in terms of better understanding of the FDp ecology and epidemiology. The findings of a survey conducted in the surroundings of three vineyards in the southern Swiss Alps aimed at studying the possible epidemiological role of the FDp secondary vector Orientus ishidae and the FDp host plant Alnus glutinosa are reported. This work demonstrates that O. ishidae is able to complete its biological cycle on A. glutinosa and to acquire FDp and 16SrV phytoplasmas very efficiently with an infection rate of 69% for the nymphal instars and 85% for the imagoes. A high prevalence of the map genotype M50 (map type FD1), which is included in the S. titanus—grapevine epidemiological cycle, was found in O. ishidae and A. glutinosa. Additionally, M12 (map type FD3), M44 and M47 were also sporadically detected. Surprisingly, the grapevines tested during this work were all infected by M54 (map type FD2) only, while the few S. titanus caught in the vineyard canopy were all FDp free. In conclusion, the occurrence of infected common alder stands and O. ishidae nearby vineyards do not seem to play a prominent role in FD epidemics in southern Switzerland. Nevertheless, wild vegetation acts as a reservoir of the FDp inoculum, which may locally trigger a FD emergence if S. titanus populations are established inside vineyards. 相似文献
8.
Marzorati M Alma A Sacchi L Pajoro M Palermo S Brusetti L Raddadi N Balloi A Tedeschi R Clementi E Corona S Quaglino F Bianco PA Beninati T Bandi C Daffonchio D 《Applied and environmental microbiology》2006,72(2):1467-1475
Flavescence dorée (FD) is a grapevine disease that afflicts several wine production areas in Europe, from Portugal to Serbia. FD is caused by a bacterium, "Candidatus Phytoplasma vitis," which is spread throughout the vineyards by a leafhopper, Scaphoideus titanus (Cicadellidae). After collection of S. titanus specimens from FD-contaminated vineyards in three different areas in the Piedmont region of Italy, we performed a survey to characterize the bacterial microflora associated with this insect. Using length heterogeneity PCR with universal primers for bacteria we identified a major peak associated with almost all of the individuals examined (both males and females). Characterization by denaturing gradient gel electrophoresis confirmed the presence of a major band that, after sequencing, showed a 97 to 99% identity with Bacteroidetes symbionts of the "Candidatus Cardinium hertigii" group. In addition, electron microscopy of tissues of S. titanus fed for 3 months on phytoplasma-infected grapevine plants showed bacterial cells with the typical morphology of "Ca. Cardinium hertigii." This endosymbiont, tentatively designated ST1-C, was found in the cytoplasm of previtellogenic and vitellogenic ovarian cells, in the follicle cells, and in the fat body and salivary glands. In addition, cell morphologies resembling those of "Ca. Phytoplasma vitis" were detected in the midgut, and specific PCR assays indicated the presence of the phytoplasma in the gut, fat body and salivary glands. These results indicate that ST1-C and "Ca. Phytoplasma vitis" have a complex life cycle in the body of S. titanus and are colocalized in different organs and tissues. 相似文献
9.
J Lherminier G Prensier E Boudon-Padieu A Caudwell 《The journal of histochemistry and cytochemistry》1990,38(1):79-85
Flavescence dorée (FD), a grapevine yellows disease, is caused by a mycoplasma-like organism (MLO). A colloidal gold indirect immunolabeling technique identified MLO in salivary glands of a vector leafhopper, Euscelidius variegatus. After aldehyde fixation, tissue samples were prepared by cryoultramicrotomy or embedding in acrylic resins. Double fixation with aldehydes and osmium retroxide, followed by embedding in epon, was also performed. Thin or semi-thin serial sections were treated with polyclonal anti-FD-MLO rabbit antibodies, then with gold-conjugated anti-rabbit IgG. Labeling was revealed using the silver enhancement technique for light microscopy. MLO in frozen thin sections of glands were efficiently labeled. Optimal results were obtained with 4% paraformaldehyde-0.1% glutaraldehyde fixation and low-temperature embedding in LR White resin. Both scattered MLO and unusual dense forms of MLO were easily detected with the electron-dense gold probe. This method distinguished MLO from other membrane-limited bodies and provided a good tool for studying infection in large regions of FD-infected tissues by light microscopy. 相似文献
10.
Henderson J 《History and philosophy of the life sciences》2003,25(4):481-499
This essay deals with plague and plagues in renaissance and early modern Europe over the longue durée, principally from a methodological perspective. I shall combine an historiographical approach with an historical account of developing reactions to plague and in passing compare measures to cope in the early sixteenth century with reactions to the impact of the Great Pox or the Mal de Naples. I shall concentrate on southern Europe and in particular on Italy and my aim is to re-assess the historiography of plague through the lens of some of the more recent Anglo-Saxon literature in this field. In the process I shall outline some of the debates within the field and end with some general methodological observations drawn from early modern Italy. 相似文献
11.
Mohammad Salehi Seyyed Alireza Esmailzadeh Hosseini Elham Salehi Assunta Bertaccini 《Archives Of Phytopathology And Plant Protection》2013,46(15-16):803-813
AbstractDuring 2013–2015 surveys in Fars, Lorestan and Yazd provinces (Iran), a field bindweed witches’ broom (FBWB) disease was observed. The main symptoms were reduction of leaves size, yellowing, internode shortening, witches’ broom and stunting. The agent of FBWB was dodder transmitted to periwinkle plants inducing phytoplasma-type symptoms. Amplifications of nearly 1.8 and 1.2 kbp were, respectively, obtained from 15 symptomatic bindweed plants and 28 symptomatic dodder-inoculated periwinkles. Virtual RFLP analyses showed that the phytoplasma detected belonged to 16SrXII-A subgroup, and it was the same in all the samples examined; phylogenetic analyses confirmed it as a ‘Candidatus Phytoplasma solani’-related strain. This is the first report of 16SrXII-A phytoplasmas presence in bindweed plants showing witches’ broom symptoms in Fars, Lorestan and Yazd provinces. As a perennial widespread weed, it may act as a 16SrXII-A phytoplasma source for alfalfa, grapevine, Sophora alopecuroides, tomato, hemp and Japanese spindle reported diseases in these Iranian provinces. 相似文献
12.
Jean-Paul Lasserre Jacqueline Plissonneau Christophe Velours Marc Bonneu Simon Litvak Patricia Laquel Michel Castroviejo 《Biochimie》2013
DNA replication occurs in various compartments of eukaryotic cells such as the nuclei, mitochondria and chloroplasts, the latter of which is used in plants and algae. Replication appears to be simpler in the mitochondria than in the nucleus where multiple DNA polymerases, which are key enzymes for DNA synthesis, have been characterized. In mammals, only one mitochondrial DNA polymerase (pol γ) has been described to date. However, in the mitochondria of the yeast Saccharomyces cerevisiae, we have found and characterized a second DNA polymerase. To identify this enzyme, several biochemical approaches such as proteinase K treatment of sucrose gradient purified mitochondria, analysis of mitoplasts, electron microscopy and the use of mitochondrial and cytoplasmic markers for immunoblotting demonstrated that this second DNA polymerase is neither a nuclear or cytoplasmic contaminant nor a proteolytic product of pol γ. An improved purification procedure and the use of mass spectrometry allowed us to identify this enzyme as DNA polymerase α. Moreover, tagging DNA polymerase α with a fluorescent probe demonstrated that this enzyme is localized both in the nucleus and in the organelles of intact yeast cells. The presence of two replicative DNA polymerases may shed new light on the mtDNA replication process in S. cerevisiae. 相似文献
13.
Ajay Kumar Tiwari Kavita Kumari Neeraj Nath Tiwari Pradeep Kumar Akil Ahmad Khan 《Archives Of Phytopathology And Plant Protection》2013,46(17-20):931-935
During the survey of two successive years 2012–2013, in nearby places of Gorakhpur districts, Uttar Pradesh, India, Arundo donax plants were found to be exhibiting witches’ broom, excessive branching accompanied with little leaf symptoms with considerable disease incidence. Nested PCR carried out with universal primers pair R16F2n/R16R2 employing the PCR (P1/P7) product as a template DNA (1:20) resulted in expected size positive amplification ~1.2 kb in all symptom-bearing plants suggested the association of phytoplasma with witches’ broom disease of Narkat plants. BLASTn analysis of the 16S rRNA gene sequence showed the highest (99%) sequence identity with Candidatus phytoplasma asteris (16SrI group). In phylogenetic analysis, the sequence data showed close relationships with the members of 16SrI phytoplasma and clustered within a single clade of 16SrI group and closed to B subgroup representatives. This is a first report of 16Sr I-B group phytoplasma associated with witches’ broom accompanied with little leaf disease of Narkat in India. 相似文献
14.
A : Comparison of two commercial miniaturized rapid systems for the identification of Ralstonia pickettii strains. METHODS AND RESULTS: Varying identification results were encountered using the bioMérieux API NE system and the Remel IDS RapID NF Plus commercial systems for R. pickettii. To compare these two systems, eight strains of R. pickettii were purchased from different commercial culture collections. Additionally, 32 industrial and eight clinical isolates, initially identified using the Vitek Junior (bioMérieux) were tested. Total number of isolates tested was 48. The API 20NE identified 29 isolates, as R. pickettii but was unsuccessful with 19 isolates. The Remel IDS RapID NF Plus identified 46 isolates as R. pickettii. One clinical and one industrial isolates was identified as non-R. pickettii with both systems. CONCLUSIONS: The above results indicate that the use of API 20NE system for examining the identification of R. pickettii strains is inconsistent. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrated that the RapID NF Plus is more accurate as an inexpensive identification system for the identification of R. pickettii, a potential emerging organism of medically and industrial importance. 相似文献
15.
Gabbay YB Linhares AC Oliveira DS Nakamura LS Mascarenhas JD Gusmão RH Heinemann MB Macêdo O Leite JP 《Memórias do Instituto Oswaldo Cruz》2007,102(4):531-534
This study describes the genetic relationships of the first human astrovirus type-8 (HAstV-8) detected in Belém-Brazil, during a public hospital-based study. This strain was compared with other HAstV-8 strains identified elsewhere which have sequences available at GeneBank. The regions ORF1a (primers Mon348/Mon340) and ORF2 (primers Mon269/Mon270) were analyzed by nucleotide sequencing and a high similarity rate was observed among the Belém strain and other HAstV-8 strains. In ORF1a, homology values of 93-100% were detected, and in ORF2 96-99%. Considering the sequence variation (7%) observed in ORF2 region, it was suggested that HAstV-8 strains could be divided in three different lineages. 相似文献
16.
A. Meraner A. Venturi G. F. Ficetola S. Rossi A. Candiotto A. Gandolfi 《Molecular ecology》2013,22(21):5295-5312
Biological invasions and introgressive hybridization are major drivers for the decline of native freshwater fish. However, the magnitude of the problem across a native species range, the mechanisms shaping introgression as well as invader's dispersal and the relative role of biological invasions in the light of multiple environmental stressors are rarely described. Here, we report extensive (N = 665) mtDNA sequence and (N = 692) microsatellite genotypic data of 32 Northern Adriatic sites aimed to unravel the invasion of the European Barbus barbus in Italy and the hybridization and decline of the endemic B. plebejus. We highlight an exceptionally fast breakthrough of B. barbus within the Po River basin, leading to widespread introgressive hybridization with the endemic B. plebejus within few generations. In contrast, adjacent drainage systems are still unaffected from B. barbus invasion. We show that barriers to migration are inefficient to halt the invasion process and that propagule pressure, and not environmental quality, is the major driver responsible for B. barbus success. Both introgressive hybridization and invader's dispersal are facilitated by ongoing fisheries management practices. Therefore, immediate changes in fisheries management (i.e. stocking and translocation measures) and a detailed conservation plan, focussed on remnant purebred B. plebejus populations, are urgently needed. 相似文献
17.
Fernanda Badotti Carmela Belloch Carlos A. Rosa Eladio Barrio Amparo Querol 《World journal of microbiology & biotechnology》2010,26(4):579-587
In this work, 74 Saccharomyces cerevisiae strains isolated from cachaça fermentation of six different geographic regions in Brazil were characterized by mitochondrial DNA restriction fragment length polymorphism (mtDNA-RFLP) and by their ability to grow on stress conditions occurring during the cachaça fermentation process. Cachaça S. cerevisiae strains showed high mtDNA-RFLP polymorphism with the occurrence of 32 different molecular patterns. The S. cerevisiae strains presenting prevalent mtDNA were able to grow better in the stress conditions than strains represented by infrequent patterns. The principal coordinate analysis on 17 stress conditions revealed that the major source of growth variation were high ethanol concentrations and low temperatures. These results indicate that the stress conditions occurring in the fermentation process influence the prevalence of the most adapted S. cerevisiae strains in each distillery. The physiological tests used in our study can be used as a criterion for rapidly selecting autochthonous yeast strains for further purposes such as the selection of fermentative starters of S. cerevisiae strains. 相似文献
18.
Oliveira VA Vicente MA Fietto LG Castro IM Coutrim MX Schüller D Alves H Casal M Santos JO Araújo LD da Silva PH Brandão RL 《Applied and environmental microbiology》2008,74(3):693-701
Saccharomyces cerevisiae strains from different regions of Minas Gerais, Brazil, were isolated and characterized aiming at the selection of starter yeasts to be used in the production of cachaça, the Brazilian sugar cane spirit. The methodology established took into account the screening for biochemical traits desirable in a yeast cachaça producer, such as no H2S production, high tolerance to ethanol and high temperatures, high fermentative capacity, and the abilities to flocculate and to produce mycocins. Furthermore, the yeasts were exposed to drugs such as 5,5′,5"-trifluor-d,l-leucine and cerulenin to isolate those that potentially overproduce higher alcohols and esters. The utilization of a random amplified polymorphic DNA-PCR method with primers based on intron splicing sites flanking regions of the COX1 gene, as well as microsatellite analysis, was not sufficient to achieve good differentiation among selected strains. In contrast, karyotype analysis allowed a clear distinction among all strains. Two selected strains were experimentally evaluated as cachaça producers. The results suggest that the selection of strains as fermentation starters requires the combined use of biochemical and molecular criteria to ensure the isolation and identification of strains with potential characteristics to produce cachaça with a higher quality standard.Cachaça (pronounced “kha-sha-ssa”), the sugar cane spirit, is the most popular distilled beverage produced in Brazil. The annual production reaches 1.3 billion liters, with 15% being produced in more than 8,500 distilleries in the state of Minas Gerais.Traditional cachaça production relies on a spontaneous fermentative process that is mediated by the microbiota present in the cane juice wort and on the surface of equipments used in the productive process. It has been already demonstrated that in such systems there occurs a succession of yeasts, with Saccharomyces cerevisiae being the predominant species. Cachaça quality depends on the ecology of the microbial populations during an initial spontaneous fermentation (18, 29, 31, 32, 39). The fermentative process occurs through a continuously open fermentative process which is completed within 24 h and generally takes place from May to November, corresponding to the sugar cane harvesting period.Considering the conditions of production usually found in the cachaça distilleries, fermenting yeast populations have to face different types of stress (osmotic, high temperature, and high ethanol concentration). Besides, they might also present some characteristics such as a good fermentative power, no H2S production, killer activity, flocculation ability, and production of flavoring compounds. Taking all of these factors into account, we have developed a strategy to select yeast strains with appropriated characteristics to produce cachaça with potentially higher-quality standards (52).Parallel to the selection and development of S. cerevisiae strains toward ethanolic fermentations, molecular methods were developed and validated to study the evolution of yeast flora in spontaneous but also in inoculated fermentations. Chromosomal karyotyping by pulsed-field gel electrophoresis is a complex and time-consuming process but is very efficient for the delimitation of S. cerevisiae strains since it makes it possible to distinguish strains at both the intra- and the interspecies levels. Numerous other methods of typing based on DNA polymorphism allow differentiating closely related yeast strains (8, 36, 43, 50). Restriction fragment length polymorphism (RFLP) analysis of mitochondrial DNA (mtDNA) is faster and easier than other methods (23, 31). Digestion of mtDNA with restriction enzymes such as HinfI or RsaI is associated with a high rate of polymorphism and has been used to study the authenticity of commercial wine yeast strains (14, 40, 41). A PCR method based on variations found on the mitochondrial COX1 (a gene coding for cytochrome oxidase) intron number and position has been validated to distinguish S. cerevisiae strains allowing researchers to monitor the evolution of wine fermentations conducted by commercial active dry yeast (27). Moreover, in many other studies, RAPD [random(ly) amplified polymorphic DNA]-PCR with different primers such as EL1 and LA1 has been successfully used to discriminate between wine yeast strains (2) and for differentiation of Saccharomyces species isolated in Brazil (18). In the last few years, fingerprinting of microsatellite or simple sequence repeat loci, short (1 to 10 nucleotides) DNA tandem repeats dispersed throughout the genome and with a high degree of variability, has proven to be useful for distinguishing S. cerevisiae strains (16, 20, 34, 40, 45). These loci exhibit a substantial level of polymorphism and have been used in humans for paternity tests and forensic medicine but also for the demonstration of population structures among indigenous S. cerevisiae strains (24, 42, 43).We describe here the isolation and characterization of S. cerevisiae strains from cachaça and the use of two of these strains in cachaça production. The strains were isolated from local producers and characterized by growth in high-alcohol, high-sugar environments and in the presence of 5,5′,5"-trifluor-d,l-leucine (TFL) and cerulenin to detect overproducers of flavor compounds. We also used molecular methods to evaluate the polymorphisms of yeast strains in the fermentative process. Our results demonstrate that some methodologies based on DNA polymorphism are insufficient to evaluate the diversity of S. cerevisiae population during the cachaça production. The utilization of specific biochemical tests is necessary in order to permit a more precise characterization of the dynamics of the selected strains during the fermentative process. Only by combining biochemical and molecular methods were we able to select strains that showed a suitable profile to be used as starters. The cachaça produced with these strains was also evaluated, and the results demonstrate that the quality of the final product is better than that obtained with a commercial strain also used to produce cachaça. 相似文献
19.
Cristian R. Teodoru Paul A. del Giorgio Yves T. Prairie Annick St-Pierre 《Biogeochemistry》2013,113(1-3):323-339
We investigated the depositional trends of total particles, carbon and nitrogen in a newly created, 600-km2 hydroelectric reservoir in Northern Québec, and compared the results with those observed in lakes of the surrounding region. We show that particulate fluxes exhibit a large degree of spatial heterogeneity in both the reservoir (68–548 mg POC m?2 d?1 and 5–33 mg PN m?2 d?1) and the natural lakes (30–150 mg POC m?2 d?1 and 3–12 mg PN m?2 d?1) and that on average, settling fluxes of the reservoir (211 ± 46 mg POC m?2 d?1 and 14 ± 3 mg PN m?2 d?1) exceeded lake deposition (79 ± 13 mg POC m?2 d?1 and 7 ± 1 mg PN m?2 d?1) by approximately two-fold. Our results also show that the nature of the organic matter reaching the sediments was significantly different between lakes and the reservoir, which can have consequences for benthic metabolism and the long-term storage. We found that sinking fluxes in the reservoir were mostly regulated by local morphological and hydrological conditions, with higher fluxes along or in the vicinity of the old riverbed (average 400 ± 73 mg POC m?2 d?1 and 24 ± 5 mg PN m?2 d?1) and lower fluxes in calmer zones such as side bays (average 106 ± 10 mg POC m?2 d?1 and 8 ± 1 mg PN m?2 d?1). In lakes, where settling fluxes were not linked to the trophy, or dissolved organic carbon, the actual nature of the sedimenting organic material was influenced by lake morphometry and the relative contribution of algal versus terrestrial sources. We conclude that re-suspension and erosion play a major role in shaping the reservoir sinking fluxes which explain both, the higher reservoir deposition and also some of the qualitative differences between the two systems. Despite all these differences, sinking particulate organic carbon fluxes were small and surprisingly similar relative to the surface carbon dioxide emissions in both the reservoir and lakes, representing approximately 16–17 % of the carbon efflux estimated for these same systems in 2008. 相似文献
20.
Pierre Nouvellet Christl A. Donnelly Marco De Nardi Chris J. Rhodes Paola De Benedictis Carlo Citterio Federica Obber Monica Lorenzetto Manuela Dalla Pozza Simon Cauchemez Giovanni Cattoli 《PloS one》2013,8(4)
Since 2006 the red fox (Vulpes vulpes) population in north-eastern Italy has experienced an epidemic of canine distemper virus (CDV). Additionally, in 2008, after a thirteen-year absence from Italy, fox rabies was re-introduced in the Udine province at the national border with Slovenia. Disease intervention strategies are being developed and implemented to control rabies in this area and minimise risk to human health. Here we present empirical data and the epidemiological picture relating to these epidemics in the period 2006–2010. Of important significance for epidemiological studies of wild animals, basic mathematical models are developed to exploit information collected from the surveillance program on dead and/or living animals in order to assess the incidence of infection. These models are also used to estimate the rate of transmission of both diseases and the rate of vaccination, while correcting for a bias in early collection of CDV samples. We found that the rate of rabies transmission was roughly twice that of CDV, with an estimated effective contact between infected and susceptible fox leading to a new infection occurring once every 3 days for rabies, and once a week for CDV. We also inferred that during the early stage of the CDV epidemic, a bias in the monitoring protocol resulted in a positive sample being almost 10 times more likely to be collected than a negative sample. We estimated the rate of intake of oral vaccine at 0.006 per day, allowing us to estimate that roughly 68% of the foxes would be immunised. This was confirmed by field observations. Finally we discuss the implications for the eco-epidemiological dynamics of both epidemics in relation to control measures. 相似文献