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In this short report, the genome-wide homologous recombination events were re-evaluated for classical swine fever virus (CSFV) strain AF407339. We challenged a previous study which suggested only one recombination event in AF407339 based on 25 CSFV genomes. Through our re-analysis on the 25 genomes in the previous study and the 41 genomes used in the present study, we argued that there should be possibly at least two clear recombination events happening in AF407339 through genome-wide scanning. The reasons for identifying only one recombination event in the previous study might be due to the limited number of available CSFV genome sequences at that time and the limited usage of detection methods. In contrast, as identified by most detection methods using all available CSFV genome sequences, two major recombination events were found at the starting and ending zones of the genome AF407339, respectively. The first one has two parents AF333000 (minor) and AY554397 (major) with beginning and ending breakpoints located at 19 and 607 nt of the genome respectively. The second one has two parents AF531433 (minor) and GQ902941 (major) with beginning and ending breakpoints at 8397 and 11,078 nt of the genome respectively. Phylogenetic incongruence analysis using neighbor-joining algorithm with 1000 bootstrapping replicates further supported the existence of these two recombination events. In addition, we also identified additional 18 recombination events on the available CSFV strains. Some of them may be trivial and can be ignored. In conclusion, CSFV might have relatively high frequency of homologous recombination events. Genome-wide scanning of identifying recombination events should utilize multiple detection methods so as to reduce the risk of misidentification.  相似文献   

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Root knot (Meloidogyne spp.) and cyst (Heterodera and Globodera spp.) nematodes infect all important crop species, and the annual economic loss due to these pathogens exceeds $90 billion. We screened the worldwide accession collection with the root-knot nematodes Meloidogyne incognita, M. arenaria and M. hapla, soybean cyst nematode (SCN-Heterodera glycines), sugar beet cyst nematode (SBCN-Heterodera schachtii) and clover cyst nematode (CLCN-Heterodera trifolii), revealing resistant and susceptible accessions. In the over 100 accessions evaluated, we observed a range of responses to the root-knot nematode species, and a non-host response was observed for SCN and SBCN infection. However, variation was observed with respect to infection by CLCN. While many cultivars including Jemalong A17 were resistant to H. trifolii, cultivar Paraggio was highly susceptible. Identification of M. truncatula as a host for root-knot nematodes and H. trifolii and the differential host response to both RKN and CLCN provide the opportunity to genetically and molecularly characterize genes involved in plant-nematode interaction. Accession DZA045, obtained from an Algerian population, was resistant to all three root-knot nematode species and was used for further studies. The mechanism of resistance in DZA045 appears different from Mi-mediated root-knot nematode resistance in tomato. Temporal analysis of nematode infection showed that there is no difference in nematode penetration between the resistant and susceptible accessions, and no hypersensitive response was observed in the resistant accession even several days after infection. However, less than 5% of the nematode population completed the life cycle as females in the resistant accession. The remainder emigrated from the roots, developed as males, or died inside the roots as undeveloped larvae. Genetic analyses carried out by crossing DZA045 with a susceptible French accession, F83005, suggest that one gene controls resistance in DZA045.  相似文献   

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Plant–parasitic cyst nematodes secrete a complex of cell wall–digesting enzymes, which aid in root penetration and migration. The soybean cyst nematode Heterodera glycines also produces a cellulose binding protein (Hg CBP) secretory protein. To determine the function of CBP, an orthologous cDNA clone (Hs CBP) was isolated from the sugar beet cyst nematode Heterodera schachtii, which is able to infect Arabidopsis thaliana. CBP is expressed only in the early phases of feeding cell formation and not during the migratory phase. Transgenic Arabidopsis expressing Hs CBP developed longer roots and exhibited enhanced susceptibility to H. schachtii. A yeast two-hybrid screen identified Arabidopsis pectin methylesterase protein 3 (PME3) as strongly and specifically interacting with Hs CBP. Transgenic plants overexpressing PME3 also produced longer roots and exhibited increased susceptibility to H. schachtii, while a pme3 knockout mutant showed opposite phenotypes. Moreover, CBP overexpression increases PME3 activity in planta. Localization studies support the mode of action of PME3 as a cell wall–modifying enzyme. Expression of CBP in the pme3 knockout mutant revealed that PME3 is required but not the sole mechanism for CBP overexpression phenotype. These data indicate that CBP directly interacts with PME3 thereby activating and potentially targeting this enzyme to aid cyst nematode parasitism.  相似文献   

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Thirty-five populations of Heterodera glycines and populations of 15 other Heterodera, Globodera, and Punctodera species were studied morphometrically and some were compared serologically. There was a wide range of each measurement within each nematode population. Except for one soybean cyst nematode population from Indiana, which was a tetraploid and considerably larger than the others, morphometric measurements overlapped. In a discriminant function comparison most of the populations were closely grouped but at least three were rather distinctly separated. Morphometrically H. fici, H. cruciferae, H. schachtii, and H. trifolii were closely associated with H. glycines. Serology indicated a close relationship between H. glycines, H. lespedezae, H. trifolii, H. schachtii, and the Heterodera sp. from Rumex, while H. betulae appeared to be more distantly related.  相似文献   

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Plant endo‐β‐1,4‐glucanases (EGases) include cell wall‐modifying enzymes that are involved in nematode‐induced growth of syncytia (feeding structures) in nematode‐infected roots. EGases in the α‐ and β‐subfamilies contain signal peptides and are secreted, whereas those in the γ‐subfamily have a membrane‐anchoring domain and are not secreted. The Arabidopsis α‐EGase At1g48930, designated as AtCel6, is known to be down‐regulated by beet cyst nematode (Heterodera schachtii) in Arabidopsis roots, whereas another α‐EGase, AtCel2, is up‐regulated. Here, we report that the ectopic expression of AtCel6 in soybean roots reduces susceptibility to both soybean cyst nematode (SCN; Heterodera glycines) and root knot nematode (Meloidogyne incognita). Suppression of GmCel7, the soybean homologue of AtCel2, in soybean roots also reduces the susceptibility to SCN. In contrast, in studies on two γ‐EGases, both ectopic expression of AtKOR2 in soybean roots and suppression of the soybean homologue of AtKOR3 had no significant effect on SCN parasitism. Our results suggest that secreted α‐EGases are likely to be more useful than membrane‐bound γ‐EGases in the development of an SCN‐resistant soybean through gene manipulation. Furthermore, this study provides evidence that Arabidopsis shares molecular events of cyst nematode parasitism with soybean, and confirms the suitability of the Arabidopsis–H. schachtii interaction as a model for the soybean–H. glycines pathosystem.  相似文献   

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Restriction fragment patterns of mitochondrial DNA from sibling species of cyst nematodes Heterodera glycines and H. schachtii were examined. Fourteen restriction endonucleases recognizing four, five, and six base-pair sequences yielded a total of 90 scorable fragments of which 10% were shared by both species. Mitochondrial genome sizes for H. glycines and H. schachtii were estimated to be 22.5-23.5 kb and 23.0 kb, respectively. A single wild type mitochondrial genome was identified in all populations of H. glycines examined, although other mitochondrial genomes were present in some populations. The H. schachtii genome exhibited 57 scorable fragments, compared with 33 identified in the H. glycines wild type genome. The estimated nucleotide sequence divergence between the two species was p = 0.145. This estimate suggests these species diverged from a common ancestor 7.3-14.8 million years ago.  相似文献   

11.
Bacteroidales species were detected in (tap) water samples from treatment plants with three different PCR assays. 16S rRNA gene sequence analysis indicated that the sequences had an environmental rather than fecal origin. We conclude that assays for Bacteroidales 16S rRNA genes are not specific enough to discern fecal contamination of drinking water in the Netherlands.Drinking water in many countries is routinely monitored for recent fecal contamination by testing for fecal indicator organisms Escherichia coli, thermotolerant coliforms, and/or intestinal enterococci to demonstrate microbial safety (13, 21, 42). Although these indicator organisms have been used for many decades, they have some limitations: the number of E. coli/coliform/enterococcus bacteria in feces is relatively low (18, 38), and they sometimes might be able to grow in the environment (10, 11, 14, 27). Consequently, scientists have been searching for alternative indicator organisms to determine fecal contamination of water. In 1967, bacteria belonging to the genus Bacteroides were suggested as alternative indicator organisms (26). Bacteroides spp. might have some advantages over the traditional indicator organisms. The numbers of Bacteroides spp. in the intestinal tract of humans and animals are 10 to 100 times higher than the numbers of E. coli or intestinal enterococci (1, 2, 12, 26). However, the use of Bacteroides spp. as indicator organisms was hampered by the complex cultivation conditions required (1, 2). The introduction of molecular methods made it possible to detect bacterial species that belong to the order Bacteroidales, an order that includes the genus Bacteroides, without cultivation. As a result, real-time PCR methods were developed for the quantitative detection of Bacteroidales in surface and recreation water and the potential of Bacteroidales species as an indication of fecal contamination of recreational waters was demonstrated (6, 12, 16, 19, 20, 29). Bacteroidales species might be useful indicator organisms for fecal contamination of drinking water as well. However, methods to detect fecal contamination in drinking water should be more sensitive, because people ingest more drinking water and the quality assessments and standards for fecal contamination are stricter than for bathing water. Studies exploring real-time PCR for the detection of Bacteroidales genes in drinking water have not been published to our knowledge. The objective of our study was, therefore, to determine if assays for the detection of Bacteroidales 16S rRNA genes can be used to detect fecal contamination in drinking water.Unchlorinated tap water samples were obtained in November 2007 and February 2010 from one or more locations in the distribution systems of nine different drinking water treatment plants (plants A to I; Table Table1)1) that produced unchlorinated drinking water from confined (plants B, C, E, F, and G) and unconfined (plants A, D, H, and I) groundwater. The treatment plants are located in the central part of the Netherlands within 90 km of each other. In addition, untreated groundwater from extraction wells and/or untreated raw groundwater (mixture of groundwater from different extraction wells) was sampled in March 2008 (Table (Table1).1). Water samples (100 ml) were filtered over a 25-mm polycarbonate filter (0.22-μm pore size, type GTTP; Millipore, Netherlands) and a DNA fragment was added as internal control to determine the recovery efficiency of DNA isolation and PCR analysis (2a, 40). DNA was isolated using a FastDNA spin kit for soil (Qbiogene, United States) according to the supplier''s protocol. Primer sets AllBac 296f and AllBac 412r, resulting in a PCR product of 108 bp, were used in combination with TaqMan probe AllBac375Bhqr to quantitatively determine the number of Bacteroidales 16S rRNA gene copies in the water samples using a real-time PCR instrument (20). The PCR cycle after which the fluorescence signal of the amplified DNA was detected (threshold cycle [CT]) was used to quantify the concentration of 16S rRNA gene copies. Quantification was based on comparison of the sample CT value with the CT values of a calibration curve graphed using known copy numbers of the Bacteroidales 16S rRNA gene, as previously described (12, 20). The correlation coefficient of the calibration curve was 0.99, and the efficiency of the PCR 95 to 105%. Finally, the Bacteroidales cell number was calculated by using the recovery rate of the internal standard and assuming five 16S rRNA gene copy numbers per cell (5). The detection limit of this gene assay was 50 Bacteroidales cells 100 ml−1 (corresponding to 10 16S rRNA gene copies per reaction mixture). Furthermore, the 16S rRNA genes that were obtained from several water samples from treatment plant C with the AllBac and TotBac (12) primer sets were sequenced, and the nearest relatives were obtained from the GenBank database using BLAST searches.

TABLE 1.

Numbers of Bacteroidales cells in extraction wells, raw groundwater, and unchlorinated tap water of nine different groundwater plants in the Netherlandsa
PlantSource of sampleNo. (100 ml−1) of Bacteroidales cells in:
200720082010
ATap water 1b5,948 ± 950
Tap water 22,682 ± 1,4591,254 ± 216
Tap water 34,362 ± 947439 ± 136
Raw water96 ± 15
BTap water 13,553 ± 9815,302 ± 2,952
Tap water 24,487 ± 3912,119 ± 1,367
Tap water 37,862 ± 4,5883,896 ± 3,003
Raw water3,209 ± 833
CTap water 1661 ± 75386 ± 199
Tap water 21,051 ± 626
Tap water 3831 ± 584
Tap water 41,254 ± 216
Extraction well 11,126 ± 262
Extraction well 22,666 ± 51
Extraction well 3<50
Raw water90 ± 44
DTap water1,103 ± 291,254 ± 216
Raw water48 ± 16
ETap water1,302 ± 2221,254 ± 216
Extraction well 1671 ± 97
FTap water1,317 ± 198
Raw water<50
GTap water 1675 ± 92439 ± 300
Tap water 2216 ± 65249 ± 98
Tap water 3154 ± 6322 ± 137
Raw water<50
HTap water7,073 ± 845
Raw water511 ± 254
ITap water1,577 ± 176
Raw water420 ± 66
Open in a separate windowaValues are the average results and standard deviations from replicate PCRs on the same water sample using the AllBac primer set (20). In November 2007, the distribution systems (tap water) of plants A, B, and G were sampled at three different locations, whereas for the other plants, one location in the distribution system was sampled. In March 2008, raw water of plants A to G was sampled, as well as one (plant E) or three (plant C) different extraction wells. Finally, in February 2010, the distribution systems of plants A, B, C, D, E, and G were sampled again.bMore than one tap water sample from a treatment plant means that samples were taken at different locations in the distribution system.The Bacteroidales 16S rRNA gene, quantified with the AllBac primer set, was detected in all tap water samples in November 2007 and February 2010. The number of cells varied between 154 and 7,862 Bacteroidales cells 100 ml−1, and the numbers in tap water of each plant were similar in 2007 and 2010 (Table (Table1).1). The Bacteroidales counts were high compared to the number of E. coli that are occasionally observed in fecally contaminated drinking water (17a) but low compared to numbers observed in surface water (4, 20, 22). Water from the extraction wells and raw water used for unchlorinated drinking water production were analyzed, and Bacteroidales species were detected in 10 out of 15 samples (Table (Table1).1). These results would imply that the extracted groundwater, raw water, and tap water were fecally contaminated. According to the Dutch drinking water decree (2b), both raw and tap water from the nine different treatment plants are regularly analyzed for fecal contamination by monitoring for E. coli, F-specific RNA phages, and somatic coliphages. For at least the last 10 years, these indicator organisms have not been detected in these waters.Additional qualitative PCR analyses using TotBac and BacUni primer sets (12, 19) targeting other parts of the Bacteroidales 16S rRNA gene were performed to confirm the presence of Bacteroidales species in the water samples of November 2007 and March 2008. Nine or 10 of the 11 samples that were positive with the AllBac primer set were also positive with the TotBac and BacUni primer sets (data not shown). The BacUni primer set has a higher detection limit (30 gene copies per PCR; 19), which could explain the difference from the results with the AllBac primer set. The TotBac primer set has the same detection limit as the AllBac primer set (12), but small differences in PCR efficiencies might have resulted in different results, since some water samples showed Bacteroidales 16S rRNA gene copy numbers around the detection limit (Table (Table1).1). Nevertheless, the additional PCR analyses demonstrated that the detection of Bacteroidales species in tap, raw, and extracted well water with the AllBac primer set was not an artifact. The primer sets used were developed in three different studies (12, 19, 20) but have been applied in a number of recent studies to detect fecal contamination of surface water (3, 4, 16, 22, 33, 34). The results from most of these studies showed that 16S rRNA genes of Bacteroidales were present in all surface water samples tested. Only Sinigalliano et al. (34) observed that 2 out of 4 water samples were negative with the TotBac primer set. However, the detection limit of the assay was not specified in that study.The nine different treatment plants tested in our study produce unchlorinated drinking water from groundwater, which is considered to be of high hygienic quality. In addition, the extraction wells are protected from fecal contamination by a protection zone where no activities related to human waste or animal manure are allowed. In the Netherlands, this protection zone is based on a 60-day residence time of the water. Previous studies have demonstrated that a residence time of 60 days is highly effective in removing fecal bacteria and viruses (30, 31, 39). Moreover, the Bacteroidales numbers in tap water in November 2007 were significantly higher than the numbers in raw groundwater in March 2008 (Mann-Whitney U test; P < 0.01). Because the recovery efficiency of the internal control was the same between raw water and tap water samples, this result demonstrates that Bacteroidales cell numbers increased during treatment and/or drinking water distribution. This result could suggest that the water was fecally contaminated during drinking water treatment and/or distribution. However, it is unlikely that the integrity of nine different treatment trains and/or supply systems was affected in the sampling period. The statutory monitoring did not show the presence of E. coli at these sites. Another hypothesis is that the increase of Bacteroidales cell numbers in tap water was caused by the growth of Bacteroidales species in (drinking) water systems. In summary, it is unexpected that the majority of the tap water, raw water, and extracted groundwater samples were fecally contaminated. These unexpected observations raise the question of whether the PCR methods detect only fecal Bacteroidales species and, thus, if the gene assays are suitable to discern fecal contamination in drinking water in the Netherlands.Sequence analyses of the Bacteroidales 16S rRNA genes were performed to determine the relatedness of sequences from the different sampling sites to sequences from the nearest relatives in the GenBank database. All sequences contained the primer regions, indicating that nonspecific amplification had not occurred in the PCRs. Because the PCR product from the AllBac primer set was small (108 bp), many 16S rRNA gene sequences (100 to 5,000) in the GenBank database were identical to the Bacteroidales 16S rRNA gene sequences obtained from groundwater and unchlorinated tap water samples from plant C. These identical 16S rRNA gene sequences were in general obtained from fecal sources, but some of them came from environmental rather than fecal sources (Table (Table2).2). The AllBac 16S rRNA gene sequences from tap water and groundwater had relative high similarities (96.3 to 100%) to sequences from bacterial species of the genera Bacteroides, Prevotella, and Tannerella (Table (Table2),2), which all belong to the order Bacteroidales.

TABLE 2.

Nearest relatives in GenBank to the Bacteroidales 16S rRNA gene sequences obtained from groundwater and unchlorinated tap water from plant C using different primer setsa
Primer set used, source of sample, and OTUsbGenBank sequence accession no.Source of sequence (GenBank sequence accession no.)SimilaritycNearest cultivated bacterium in GenBank (sequence accession no.)Similarity
AllBac
    Extraction well 1 (3/6)GQ169588Rhizosphere (EF605968)108/108Prevotella oralis (AY323522)105/108
    Extraction well 1 (3/6)GQ169589Water from watershed (DQ886209)108/108Tannerella forsythia(AB035460)107/108
    Extraction well 2 (1/6)GQ169590Phyllosphere Brazilian forest (DQ221468)108/108Tannerella forsythia(AB035460)106/108
    Extraction well 2 (5/6)GQ169591Bovine rumen (EU348207)108/108Tannerella forsythia(AB035460)106/108
    Extraction well 3 (1/6)GQ169592Phyllosphere Brazilian forest (DQ221468)108/108Prevotella oralis (AY323522)104/108
    Extraction well 3 (5/6)GQ169593Prevotella corporis (L16465)108/108Prevotella corporis (L16465)108/108
    Raw water (3/6)GQ169594Spitsbergen permafrost (EF034756)108/108Tannerella forsythia(AB035460)106/108
    Raw water (3/6)GQ169595Hindgut beetle larvae (FJ374179)108/108Tannerella forsythia(AB035460)107/108
    Tap water (6/6)GQ169596Prevotella timonensis (DQ518919)108/108Prevotella timonensis (DQ518919)108/108
    Prevotella buccalis (L16476)Prevotella buccalis (L16476)
    Prevotella ruminicola (AF218617)Prevotella ruminicola (AF218617)
    Bacteroides vulgatus (NC_009614)Bacteroides vulgatus (NC_009614)
TotBac
    Extraction well 1 (1/10)GQ169597Deep subsurface groundwater (AB237705)339/369Salinimicrobium terrae (EU135614)315/370
    Extraction well 1 (1/10)GQ169598Songhuajiang River sediment (DQ444125)363/377Paludibacter propionicigenes (AB078842)357/376
    Extraction well 1 (4/10)GQ169599Freshwater pond sediment (DQ676447)352/360Paludibacter propionicigenes (AB078842)313/372
    Extraction well 1 (4/10)GQ169600Pine River sediment (DQ833352)364/371Bacteroides oleiciplenus (AB490803)334/375
    Extraction well 2 (4/10)GQ169601Groundwater (AF273319)364/371Xanthobacillum maris (AB362815)338/375
    Extraction well 2 (6/10)GQ169602Human saliva (AB028385)381/382Prevotella intermedia (AY689226)380/382
    Extraction well 3 (1/10)GQ169603Pig manure (AY816766)354/377Bacteroides thetaiotaomicron (AE015928)311/380
    Extraction well 3 (3/10)GQ169604Pig manure (AY816867)371/376Butyricimonas virosa (AB443949)307/379
    Extraction well 3 (6/10)GQ169605Swedish lake (AY509350)343/362Parabacteroides distasonis (AB238927)320/374
    Raw water (10/10)GQ169606Prevotella timonensis (AF218617)378/379Prevotella timonensis (AF218617)378/379
    Tap water (1/10)GQ169607Deep subsurface groundwater (AB237705)338/369Salinimicrobium terrae (EU135614)312/370
    Tap water (2/10)GQ169608Yukon River, AK(FJ694652)367/372Psychroserpens burtonensis (U62913)312/375
    Tap water (7/10)GQ169609Deep subsurface groundwater (AB237705)341/369Salinimicrobium terrae (EU135614)315/370
Open in a separate windowaPrimer sets AllBac (20) and TotBac (12) were used in PCRs of samples, and GenBank was searched for relatives using BLAST.bOTUs are indicated by the values in parentheses (number of sequences belonging to the OTU/total number of sequences analyzed).cNumber of base pairs identical in both sequences/total number of base pairs in sequences.16S rRNA gene sequences obtained with the TotBac primer set were longer (∼370 bp) and did not show 100% similarity with the nearest relatives in the GenBank database (Table (Table2).2). Sequences from the GenBank database that showed the highest similarity (91.6% to 99.7%) with the 16S rRNA gene sequences from tap water and groundwater from plant C were in general isolated from environmental sources (Table (Table2).2). The 16S rRNA gene sequences from cultivated bacterial species that showed the highest similarity to the 16S rRNA gene sequences obtained in our study belonged to different genera (Table (Table2).2). Some of these genera (Salinimicrobium, Xanthobacillum, and Psychroserpens) did not belong to the order Bacteroidales. However, the 16S rRNA gene sequences from bacterial species of these genera showed low similarities with the sequences obtained in this study (83.2% to 90.1%) and six mismatches to the TotBac primers. Thus, it is unlikely that DNA from bacterial species belonging to Salinimicrobium, Xanthobacillum, and Psychroserpens was amplified in the gene assay. More importantly, the majority of the nearest environmental clone sequences retrieved from the GenBank database showed no or a single mismatch with the AllBac and TotBac primer and probe sequences. Thus, these primer sets are capable of amplifying 16S rRNA genes from bacteria that have been observed in ecosystems outside the intestinal tract of humans and animals.16S rRNA gene sequences related to Prevotella species were commonly observed in extracted groundwater, raw water, and tap water (Table (Table2).2). The isolation of Prevotella paludivivens from rice roots in a rice field soil (35) demonstrated the environmental nature of some Prevotella species. In addition, primer sequences developed for the detection of fecal Bacteroidales species (8, 12, 19, 20, 25, 29) showed no or a single mismatch with 16S rRNA gene sequences from P. paludivivens, Xylanibacterium oryzae, Paludibacter propionicigenes, Proteiniphilum acetatigenes, and Petrimonas sulfuriphila that are present in the GenBank database. These five Bacteroidales species have all been isolated from ecosystems other than the gastrointestinal tract. Consequently, primer sets for 16S rRNA genes of Bacteroidales species cannot always be used to discern fecal contamination in water.A number of 16S rRNA gene sequences observed in groundwater and tap water fell in the genus Bacteroides. The presence of Bacteroides 16S rRNA gene sequences in groundwater and tap water might also suggest that some Bacteroides species are capable of growth in the environment. However, until now, type strains of Bacteroides species growing outside the animal intestinal tract have not been published. Another possible explanation is that the observed 16S rRNA gene sequences originate from Bacteroides species that inhabit the anoxic intestinal tract of insects. Previous studies have shown that bacterial species belonging to the genus Bacteroides are common inhabitants of the hindguts of insects (15, 23, 24, 28, 32). Some of the 16S rRNA gene sequences obtained with the AllBac primer set in our study showed 100% similarity to 16S rRNA gene sequences from the hindgut of insects. Moreover, a number of 16S rRNA gene sequences isolated from the hindguts of insects (15, 23, 24, 32) showed no or a single mismatch with the TotBac and AllBac primer and probe sequences. In conclusion, these primer sets are capable of detecting Bacteroides species from the hindgut of insects as well. Water insects are normal inhabitants of groundwater and drinking water distribution systems (7, 41) and might be a source of Bacteroides species in water. Bacteroides species from insect feces do not indicate fecal pollution by warm-blooded animals, and insects do not normally shed human fecal pathogenic microorganisms. Bacteroides species from insect feces, therefore, can hamper Bacteroides gene assays developed for the detection of water fecally contaminated by warm-blooded animals. Additional cultivation techniques in combination with molecular tools are required to demonstrate the persistence or growth of Bacteroides bacteria in groundwater and drinking water or whether Bacteroides bacteria are present in water insects. However, these experiments were beyond the scope of our study.The three extraction wells of plant C are located close to each other and extract water from the same aquifer. Subsequently, extracted water from the three wells is mixed and enters the treatment plant as raw water. We hypothesize that if a fecal source in the vicinity of the extraction field of plant C contaminated the groundwater, water from the extraction wells and raw water should (partly) have the same Bacteroidales species. Although a relatively limited amount of clones was sequenced per sample (16), the diversity of Bacteroidales operational taxonomic units (OTU) within a sample was low (Table (Table2).2). In contrast, unique 16S rRNA gene sequences were observed between the different water types (e.g., extracted groundwater, raw water, and tap water) and sequence overlap between water types was low. These results demonstrate that the Bacteroidales 16S rRNA gene sequences at the sampling locations were not from the same fecal source and imply once again that Bacteroidales species were environmental rather than fecal.Finally, we hypothesized that if the Bacteroidales species observed in tap water were of nonfecal origin, human- and/or bovine-specific Bacteroidales strains should not be present in tap water. We tested for the presence of human- or bovine-specific Bacteroidales strains by using source-specific 16S rRNA gene assays (5) on tap water samples from February 2010. The results showed that human- and bovine-specific Bacteroidales 16S rRNA genes could not be detected in tap water, whereas a PCR product was always detected with the positive control. Again, these results indicate that the Bacteroidales species observed in tap water were of nonfecal origin.Overall, the results from our study indicate that gene assays for Bacteroidales detected environmental rather than fecal Bacteroidales species in groundwater and tap water from treatment plants in the Netherlands. First, Bacteroidales 16S rRNA gene sequences obtained from water samples taken at plant C showed (high) similarity to clone sequences that were isolated from environmental sources. The majority of these clone sequences and several Bacteroides clone sequences from the hindguts of insects showed no or a single mismatch with AllBac, TotBac, and BacUni primer and probe sequences. Second, the primer and probe sequences used for the gene assays have no or a single mismatch with 16S rRNA gene sequences of environmental Bacteroidales species P. paludivivens, X. oryzae, P. propionicigenes, P. acetatigenes, and/or P. sulfuriphila (9, 17, 35-37). Third, Bacteroidales 16S rRNA gene sequences from raw water and water from extraction wells were unique, and sequence overlap between water types was low. It is expected that in the case of fecal contamination of groundwater, different water types from the same groundwater area have similar Bacteroidales species. Fourth, the quantitative assays for Bacteroidales 16S rRNA genes commonly used to detect fecal contamination (3, 4, 12, 16, 19, 20, 22, 33, 34) detected Bacteroidales species in deep groundwater and tap water that have no history of fecal contamination. Fifth, Bacteroidales gene copy numbers were significantly higher in tap water than in raw groundwater, demonstrating an increase or growth of Bacteroidales species during the treatment and/or distribution of drinking water. Finally, human- and bovine-specific Bacteroidales strains were not detected in tap water. Consequently, (quantitative) assays for general Bacteroidales 16S rRNA genes are not suitable to discern fecal contamination in groundwater and unchlorinated drinking water in the Netherlands.Nucleotide sequence accession numbers.The 16S rRNA gene sequences obtained in this study were deposited in the GenBank database under accession numbers GQ169588 to GQ169609.  相似文献   

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Long non-coding RNAs (lncRNAs) are key regulatory molecules involved in a variety of biological processes and human diseases. However, the pathological effects of lncRNAs on primary varicose great saphenous veins (GSVs) remain unclear. The purpose of the present study was to identify aberrantly expressed lncRNAs involved in the prevalence of GSV varicosities and predict their potential functions. Using microarray with 33,045 lncRNA and 30,215 mRNA probes, 557 lncRNAs and 980 mRNAs that differed significantly in expression between the varicose great saphenous veins and control veins were identified in six pairs of samples. These lncRNAs were sub-grouped and mRNAs expressed at different levels were clustered into several pathways with six focused on metabolic pathways. Quantitative real-time PCR replication of nine lncRNAs was performed in 32 subjects, validating six lncRNAs (AF119885, AK021444, NR_027830, G36810, NR_027927, uc.345-). A coding-non-coding gene co-expression network revealed that four of these six lncRNAs may be correlated with 11 mRNAs and pathway analysis revealed that they may be correlated with another 8 mRNAs associated with metabolic pathways. In conclusion, aberrantly expressed lncRNAs for GSV varicosities were here systematically screened and validated and their functions were predicted. These findings provide novel insight into the physiology of lncRNAs and the pathogenesis of varicose veins for further investigation. These aberrantly expressed lncRNAs may serve as new therapeutic targets for varicose veins. The Human Ethnics Committee of Shanghai East Hospital, Tongji University School of Medicine approved the study (NO.: 2011-DF-53).  相似文献   

15.
A filamentous, nonsporulating fungus, designated Arkansas Fungus 18 (ARF18), was isolated from 9 of 95 populations of Heterodera glycines, the soybean cyst nematode, in Arkansas. In petri dishes, ARF18 parasitized 89% of H. glycines eggs in cysts. The fungus also infected eggs of Meloidogyne incognita and eggs in cysts of Cactodera betulae, H. graminophila, H. lespedezae, H. leuceilyma, H. schachtii, and H. trifolii. In pot tests, reproduction of SCN was 70% less in untreated field soil that was naturally infested by ARF18 than in autoclaved field soil. Although ARF18 grew well at 25 C on cornmeal agar over a wide pH range, it did not sporulate on 28 media and thus could not be identified to genus or species.  相似文献   

16.
Root-knot nematodes (RKN) are the most serious plant parasitic nematodes having a broad host range exceeding 2,000 plant species. Quercus brantii Lindl. and Q. infectoria Oliv are the most important woody species of Zagros forests in west of Iran where favors sub-Mediterranean climate. National Botanical Garden of Iran (NBGI) is scheduled to be the basic center for research and education of botany in Iran. This garden, located in west of Tehran, was established in 1968 with an area of about 150 ha at altitude of 1,320 m. The Zagros collection has about 3-ha area and it has been designed for showing a small pattern of natural Zagros forests in west of Iran. Brant’s oak (Q. brantii) and oak manna tree (Q. infectoria) are the main woody species in Zagros collection, which have been planted in 1989. A nematological survey on Zagros forest collection in NBGI revealed heavily infection of 24-yr-old Q. brantii and Q. infectoria to RKN, Meloidogyne hapla. The roots contained prominent galls along with egg sac on the surface of each gall. The galls were relatively small and in some parts of root several galls were conjugated, and all galls contained large transparent egg masses. The identification of M. hapla was confirmed by morphological and morphometric characters and amplification of D2-D3 expansion segments of 28S rRNA gene. The obtained sequences of large-subunit rRNA gene from M. hapla was submitted to the GenBank database under the accession number KP319025. The sequence was compared with those of M. hapla deposited in GenBank using the BLAST homology search program and showed 99% similarity with those KJ755183, GQ130139, DQ328685, and KJ645428. The second stage juveniles of M. hapla isolated from Brant’s oak (Q. Brantii) showed the following morphometric characters: (n = 12), L = 394 ± 39.3 (348 to 450) µm; a = 30.9 ± 4 (24.4 to 37.6); b = 4.6 ± 0.44 (4 to 5.1); b΄ = 3.3 ± 0.3 (2.7 to 3.7), c = 8.0 ± 1 (6.2 to 10.3), ć = 5.3 ± 0.8 (3.5 to 6.3); Stylet = 12.1 ± 0.8 (11 to 13) µm; Tail = 50 ± 5.6 (42 to 57) µm; Hyaline 15 ± 1.8 (12 to 18) µm. Oak manna, Q. infectoria population of second stage juveniles clearly possessed short body length and consequently other morphometric features were less than those determined for Q. brantii population, and these features were: (n = 12), L = 359.0 ± 17.3 (319 to 372) µm; a = 28.6 ± 3 (22.8 to 31); b = 5.0 ± 0.3 (4.8 to 5.2); b΄ = 3.3 ± 0.2 (3 to 3.6), c = 8.1 ± 0.5 (7.4 to 8.8), ć = 4.7 ± 0.5 (3.9 to 5.2); Stylet = 11.4 ± 0.7 (10 to 12) µm; Tail = 44 ± 1.8 (42 to 47) µm; Hyaline 12 ± 1.7 (10 to 15) µm. To date two species of Meloidogyne, M. querciana Golden, 1979 and M. christiei Golden and Kaplan, 1986 have been reported to parasitize oaks (Quercus spp.) from the United States of America. M. querciana was found on pin oak Quercus palustris in Virginia. The oak RKN infected pine oak, red oak, and American chestnut heavily in greenhouse tests (Golden, 1979). The other species M. christiei was described from turkey oak and Q. laevis in Florida, which has monospecific host range (Golden and Kaplan, 1986). Both of these RKN species seem to be restricted to the United States of America and have not been reported from other place. According to our knowledge this is the first report of occurrence of M. hapla on Q. brantii and Q. infectoria in the world. This study includes these two oak species to the host range of RKN, M. hapla for the world and expands the information of RKN, M. hapla host ranges on oaks.  相似文献   

17.
Escherichia coli (ETEC) strain H10407 contains a GTPase virulence factor, LeoA, which is encoded on a pathogenicity island and has been shown to enhance toxin release, potentially through vesicle secretion. By sequence comparisons and X-ray structure determination we now identify LeoA as a bacterial dynamin-like protein (DLP). Proteins of the dynamin family remodel membranes and were once thought to be restricted to eukaryotes. In ETEC H10407 LeoA localises to the periplasm where it forms a punctate localisation pattern. Bioinformatic analyses of leoA and the two upstream genes leoB and leoC suggest that LeoA works in concert with a second dynamin-like protein, made up of LeoB and LeoC. Disruption of the leoAB genes leads to a reduction in secretion of periplasmic Tat-GFP and outer membrane OmpA. Our data suggest a role for LeoABC dynamin-like proteins in potentiating virulence through membrane vesicle associated toxin secretion.  相似文献   

18.
An endolichenic fungus, Xylaria grammica strain EL000614, showed strong nematicidal effects against plant pathogenic nematode, Meloidogyne incognita by producing grammicin. We report genome assembly of X. grammica EL000614 comprised of 25 scaffolds with a total length of 54.73 Mb, N50 of 4.60 Mb, and 99.8% of BUSCO completeness. GC contents of this genome were 44.02%. Gene families associated with biosynthesis of secondary metabolites or regulatory proteins were identified out of 13,730 gene models predicted.  相似文献   

19.
The nematophagous fungus Dactylella oviparasitica is considered the primary cause of a sugar beet cyst nematode (Heterodera schachtii) population suppression in a field at the Agricultural Operations, University of California, Riverside. Parasitism of H. schachtii by the ascomycete D. oviparasitica was studied using both Arabidopsis thaliana (type Landsberg erecta) and cabbage as host plants in gnotobiotic agar culture. Suitability of Arabidopsis as a host for H. schachtii was confirmed using seedlings grown with the nematode in axenic sand culture. Both developing males and females of H. schachtii broke through the Arabidopsis root surface during late juvenile stages and both were susceptible to D. oviparasitica parasitism. In contrast to Arabidopsis, developing juvenile males remained in nearly all observed cases enclosed within the cabbage root tissues while the larger body expansion of the female juveniles caused the root cortex to split; consequently only the latter ones were accessible to the fungus. In the presence of D. oviparasitica, the number of females with eggs was reduced by more than 95% and the number of eggs per female by almost 60% as compared to females developing on plates without the fungus. Viable eggs were not susceptible to parasitism while more than 90% of heat- or cold-killed eggs were rendered susceptible. These observations suggest that parasitism of developing juveniles may be the essential mode of action in the population suppression of H. schachtii.  相似文献   

20.
Embryonic Stem cells (ESCs) can be differentiated into ectoderm, endoderm, and mesoderm derivatives, producing the majority of cell types. In regular culture conditions, ESCs'' self-renewal is maintained through molecules that inhibit spontaneous differentiation enabling long-term cellular expansion. This undifferentiating condition is characterized by multiple metastable states that fluctuate between self-renewal and differentiation balance. Here, we aim to characterize the high-pluripotent ESC metastate marked by the expression of Zscan4 through a supervised machine learning framework based on an ensemble of support vector machine (SVM) classifiers. Our study revealed a leukaemia inhibitor factor (Lif) dependent not-canonical pluripotency signature (AF067063, BC061212, Dub1, Eif1a, Gm12794, Gm13871, Gm4340, Gm4850, Tcstv1/3, and Zfp352), that specifically marks Zscan4 ESCs'' fluctuation. This novel ESC metastate is enhanced by high-pluripotency culture conditions obtained through Extracellular signal Regulated-Kinase (ERK) and Glycogen synthase kinase-3 (Gsk-3) signaling inhibition (2i). Significantly, we reported that the conditional ablation of the novel ESC metastate marked by the expression of Gm12794 is required for ESCs self-renewal maintenance. In conclusion, we extend the comprehension of ESCs biology through the identification of a novel molecular signature associated to pluripotency programming.  相似文献   

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