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1.
A disease with symptoms similar to palm lethal yellowing was noticed in the early 2013 in Khuzestan Province (Iran) in date palm (Phoenix dactylifera). Infected trees displaying symptoms of streak yellows and varied in the incidence and severity of yellowing. A study was initiated to determine whether phytoplasma was the causal agent. Polymerase chain reaction–restriction fragment length polymorphism (PCR‐RFLP) methods using universal phytoplasma primers pairs R16mF1/mR1 and M1/M2 were employed to detect putative phytoplasma(s) associated with date palm trees. Nested PCR using universal primers revealed that 40 out of 53 trees were positive for phytoplasma while asymptomatic date palms from another location (controls) tested negative. RFLP analyses and DNA sequencing of 16S rDNA indicated that the presence of two different phytoplasmas most closely related to clover proliferation (CP) phytoplasma (group 16SrVI) and ash yellows (AY) phytoplasma (group 16SrVII). Sequence analysis confirmed that palm streak yellows phytoplasmas in each group were uniform and to be phylogenetically closest to “CandidatusP. fraxini” (MF374755) and “Ca. P. trifolii” isolate Rus‐CP361Fc1 (KX773529). Result of RFLP analysis of secA gene of positive samples using TruI and TaqI endonuclease is in agreement with rDNA analysis. On this basis, both strains were classified as members of subgroups 16SrVI‐A and 16SrVII‐A. This is the first report of a phytoplasma related to CP and AY phytoplasma causing date palm yellows disease symptoms. 相似文献
2.
Isothermal recombinase polymerase amplification (RPA) assays for the specific detection of “Candidatus Phytoplasma mali (Ca. P. mali),” the causal agent of apple proliferation, were developed. The assays amplify a fragment of the imp gene and amplimers were detected either by fluorescence in real‐time mode (TwistAmp®exo assay) using a fluorophore‐labelled probe or by direct visualization employing a lateral flow device (TwistAmp®nfo assay/Milenia®HybriDetect). The RPA assays specifically amplified DNA from “Ca. P. mali” strains, and cross‐reactivity with other phytoplasmas or plant DNA was not observed. The limit of detection was determined with a cloned imp standard, and positive results were obtained down to 10 copies with both RPA assay formats. In comparison with a TaqMan real‐time PCR assay based on the same target gene, the RPA assays were equally sensitive, but results were obtained faster. Simplified nucleic acid extraction procedures from plant tissue with Tris‐ and CTAB‐based buffers revealed that crude Tris–DNA extracts were a suitable source for RPA tests while larger concentrations of CTAB were inhibitory. This is the first report of RPA‐based assays for the detection of “Ca. P. mali”. The assays are suitable for high‐throughput screening of plant material and point‐of‐care diagnostic and can be potentially combined with a simplified DNA extraction procedure. 相似文献
3.
Parham Hosseini Masoud Bahar Golnoush Madani Leila Zirak 《Journal of Phytopathology》2011,159(4):241-246
Potato plants with symptoms suggestive of potato purple top disease (PPTD) occurred in the central, western and north‐western regions of Iran. Polymerase chain reaction (PCR) and nested PCR assays were performed using phytoplasma universal primer pair P1/P7 followed by primer pairs R16F2n/R16R2 and fU5/rU3 for phytoplasma detection. Using primer pairs R16F2n/R16R2 and fU5/rU3 in nested PCR, the expected fragments were amplified from 53% of symptomatic potatoes. Restriction fragment length polymorphism (RFLP) analysis using AluI, CfoI, EcoRI, KpnI, HindIII, MseI, RsaI and TaqI restriction enzymes confirmed that different phytoplasma isolates caused PPTD in several Iranian potato‐growing areas. Sequences analysis of partial 16S rRNA gene amplified by nested PCR indicated that ‘Candidatus Phytoplasma solani’, ‘Ca. Phytoplasma astris’ and ‘Ca. Phytoplasma trifolii’ are prevalent in potato plants showing PPTD symptoms in the production areas of central, western and north‐western regions of Iran, although ‘Ca. Phytoplasma solani’ is more prevalent than other phytoplasmas. This is the first report of phytoplasmas related to ‘Ca. Phytoplasma astris’, ‘Ca. Phytoplasma solani’ and ‘Ca. Phytoplasma trifolii’ causing PPTD in Iran. 相似文献
4.
Recently, peach trees showing leaf rolling, little leaf, rosetting, yellowing, bronzing of foliage and tattered and shot‐holed leaves symptoms were observed in peach growing areas in the central and north‐western regions of Iran. Polymerase chain reaction (PCR) and nested PCR using phytoplasma universal primer pairs P1/Tint, R16F2/R2, PA2F/R and NPA2F/R were employed to detect phytoplasmas. The nested PCR assays detected phytoplasma infections in 51% of symptomatic peach trees in the major peach production areas in East Azerbaijan, Isfahan, ChaharMahal‐O‐Bakhtiari and Tehran provinces. Restriction fragment length polymorphism (RFLP) analyses of 485 bp fragments amplified using primer pair NPA2F/R in nested PCR revealed that the phytoplasmas associated with infected peaches were genetically different and they were distinct from phytoplasmas that have been associated with peach and almond witches’‐broom diseases in the south of Iran. Sequence analyses of partial 16S rDNA and 16S–23S rDNA intergenic spacer regions demonstrated that ‘Candidatus Phytoplasma aurantifolia’, ‘Ca. Phytoplasma solani’ and ‘Ca. Phytoplasma trifolii’ are prevalent in peach growing areas in the central and north‐western regions of Iran. 相似文献
5.
Marshall T. Newman 《American journal of physical anthropology》1976,45(3):667-672
Various workers, including T. D. Stewart, claim that the aboriginal Americas were relatively disease-free because of the Bering Strait cold-screen, eliminating many pathogens, and the paucity of zoonotic infections because of few domestic animals. Evidence of varying validity suggests that precontact Americans had their own strains of treponemic infections, bacillary and amoebic dysenteries, influenza and viral pneumonia and other respiratory diseases, salmonellosis and perhaps other food poisoning, various arthritides, some endoparasites such as the ascarids, and several geographically circumscribed diseases such as the rickettsial verruca (Carrion's disease) and New World leishmaniasis and trypanosomiasis. Questionably aboriginal are tuberculosis and typhus. Accordingly, virtually all the “crowd-type” ecopathogenic diseases such as smallpox, yellow fever, typhoid, malaria, measles, pertussis, polio, etc., appear to have been absent from the New World, and were only brought in by White conquerors and their Black slaves. My hypothesis is that native American medical care systems—especially in the more culturally advanced areas—were sufficiently sophisticated to deal with native disease entities with reasonable competence. But native medical systems could not cope with the “crowd-type” disease imports that struck Indian and Eskimos as “virgin field” populations. Reanalysis of native population losses through a genocidal combination of disease, war, slavery and attendant cultural disruption by Dobyns, Cook and others strongly suggest that traditional estimates underplayed the death toll by a factor of the general order of ten. This would make for an immediately pre-contact Indian population of some 90–111 million instead of the traditional 8–11 million. Evidence is growing that Indians may have been no more susceptible to new pathogens than are other “virgin soil” populations, and thus their immune systems need not be considered less effective than those in other people. Present-day high mortality rates in Indians of both continents from infectious disease imports may be more socioeconomic than anything else. 相似文献
6.
Pear trees showing pear decline disease symptoms were observed in pear orchards in the centre and north of Iran. Detection of phytoplasmas using universal primer pair P1A/P7A followed by primer pair R16F2n/R16R2 in nested PCR confirmed association of phytoplasmas with diseased pear trees. However, PCR using group‐specific primer pairs R16(X)F1/R16(X)R1 and rp(I)F1A/rp(I)R1A showed that Iranian pear phytoplasmas are related to apple proliferation and aster yellows groups. Moreover, PCR results using primer pair ESFYf/ESFYr specific to 16SrX‐B subgroup indicated that ‘Ca. Phytoplasma prunorum’ is associated with pear decline disease in the north of Iran. RFLP analyses using HaeIII, HhaI, HinfI, HpaII and RsaI restriction enzymes confirmed the PCR results. Partial 16S rRNA, imp, rp and secY genes sequence analyses approved that ‘Ca. Phytoplasma pyri’ and ‘Ca. Phytoplasma asteris’ cause pear decline disease in the centre of Iran, whereas ‘Ca. Phytoplasma prunorum’ causes disease in the north of Iran. This is the first report of the association of ‘Ca. Phytoplasma asteris’ and ‘Ca. Phytoplasma prunorum’ with pear decline disease worldwide. 相似文献
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Assunta Bertaccini Nicoletta Contaldo Alessandro Benni Massimo Curini Salvatore Genovese Francesco Epifano Maria Grazia Bellardi 《Journal of Phytopathology》2011,159(2):124-126
Grindelia robusta, a perennial herb, contains an essential oil that is used as an antitussive, sedative, and analgesic agent. During the spring of 2007, ‘Candidatus Phytoplasma asteris’‐related phytoplasmas were identified in plants showing virescence and phyllody symptoms. The qualitative and quantitative composition of the oil of healthy and infected plants was compared by gas chromatography/mass spectrometry. Samples from six symptomatic and five asymptomatic plants tested by nested PCR followed by RFLP analyses confirmed the presence of ‘Ca. P. asteris’ in all symptomatic samples. The oils from healthy and infected plants, obtained by steam distillation, contained 42 components; that of healthy plants contained a higher concentration of monoterpenes, especially limonene and bornyl acetate, which were nearly 50% higher. 相似文献
10.
Pseudomonas tolaasii, causing brown blotch disease on cultivated mushrooms, and yielding a white line precipitate towards P. “reactans”, has been shown to induce lysis of erythrocytes. Some Finnish strains isolated from diseased mushroom fruit bodies, although harboring the typical features of P. tolaasii, proved to be distinct, and have been allocated to a nov. sp. P. costantinii. We examined in these study whether all brown blotch causing agents were hemolytic. The induction of erythrocytes lysis seemed to be a rather common feature of mushroom associated-pseudomonads, especially for strains involved in the production of a white-line-in agar. 相似文献
11.
María A. Mendoza‐Becerril Adrian José Jaimes‐Becerra Allen G. Collins Antonio C. Marques 《Zoologica scripta》2018,47(5):608-622
We present phylogenetic analyses (parsimony, maximum likelihood and Bayesian inference) for 69 lineages of anthoathecate hydroids based on 18 morphological characters (12 proposed for the first time) plus mitochondrial (16S and COI) and nuclear (18S and 28S) molecular markers. This study aims to test the monophyly of the present concept of the family Bougainvilliidae, assessing its phylogenetic position within Hydroidolina. Our working hypothesis is used as a context for inferring the evolution of certain morphological characters, focusing on the exoskeleton. Our results shed light on some phylogenetic uncertainties within Hydroidolina, delimiting eight well‐supported linages, viz. Hydroidolina, Siphonophorae, Leptothecata, Aplanulata, Filifera II, Filifera III, Capitata and Pseudothecata taxon novum, the latter supported by four morphological synapomorphies. The monophyly of several families was not supported, viz. Bougainvilliidae, Cordylophoridae, Oceaniidae, Rathkeidae and Pandeidae. Some of the genera typically considered in Bougainvilliidae, including Bougainvillia, fell into the clade Pseudothecata, which is consistently reconstructed as the sister group of Leptothecata. We formally suggest that Dicoryne be removed from Bougainvilliidae and placed in the resurrected family Dicorynidae. The exoskeleton was a key feature in the diversification of Hydroidolina, especially with the transition from the bare hydranth to one completely enveloped within the exoskeleton. In this context, bougainvilliids exhibit several intermediate states in the development of the exosarc. Although the concatenated analysis unravels some interesting hypotheses, taxon sampling is still deficient and therefore more data are necessary for achieving a more complete understanding of the evolution and ecology of bougainvilliids and their allies. 相似文献
12.
Susan J. Bartleit Myles S. Faith Kevin R. Fontaine Lawrence J. Cheskin David B. Allison 《Obesity (Silver Spring, Md.)》1999,7(4):407-413
BARTLETT, SUSAN J., MYLES S. FAITH, KEVIN R. FONTAINE, LAWRENCE J. CHESKIN, AND DAVID B. ALLISON. Is the prevalence of successful weight loss and maintenance higher in the general community than the research clinic? Obes Res. Objective: The prevalence of successful weight loss remains unclear. In 1982, Schachter concluded that in the general population, the rate of “self-cured” obesity approached 63%–much higher than the rate from clinical trials. Several subsequent studies have addressed this issue. Research Methods and Procedures: Our initial goal was to meta-analyze these studies to evaluate the validity of the original hypotheses and the extent to which additional investigations supported the findings. We began by restating Schachter's hypotheses in precise, testable terms. Results: A systematic review of these studies found many methodological limitations and much heterogeneity among the samples studied, hypotheses addressed, and operational definitions. Some of these limitations appear to stem from the lack of clear, precise statements of the exact hypotheses tested. Differences among studies are delineated, and we outline why meta-analytic pooling of these data appears inappropriate. Conclusions: The current data are inadequate to draw any definite conclusions regarding the cure rate of obesity. Criteria for the adequate study of success rates with “self-cure” in the general population are proposed. 相似文献
13.
Carey P. Yeager 《American journal of primatology》1990,20(2):95-106
Proboscis monkey (Nasalis larvatus) social organization was studied at the Tanjung Puting National Park in Kalimantan Tengah, Indonesia, for 12 months. Data were collected on one-male groups and all-male groups by using scan sampling and event sampling while following groups. Evening census surveys were also conducted. Proboscis monkeys were found to follow the typical Asian colobine pattern of one-male social groups, with extra-group males forming all-male groups. These groups appear stable, with few changes in membership. One-male groups appear to be “female bonded”; adult females direct affiliative behaviors towards their offspring and other adult females, not towards the male. Nearest-neighbor data indicate some peripheralization of juvenile animals. 相似文献
14.
Biophysical methods allow quantitative deductions as to the “bending effectivity” of various stele types and the contribution of different tissues to the stability of upright plant axes. Considering the first occurrence of the different stele types in geological history, a strong tendency towards a higher “bending effectivity” can be observed. It can be shown that Rhynia gwynne-vaughanii, Aglaophyton major (Rhynia major) and Asteroxylon mackiei as well as probably the vast majority of early “vascular” land plants were turgor systems, i.e. that the parenchyma (when fully turgescent) is by far the most important contributory factor towards the bending stability of the upright axes. 相似文献
15.
C. S. Nwadiaro 《International Review of Hydrobiology》1989,74(6):633-642
Preliminary observations were made between October 1982 and May 1983 on the nature, taxonomic composition, spatial distribution, buoyancy behaviour and nutrient requirements of some unusual planktonic algal “jellies” in Oguta Lake in Southeastern Nigeria. These “jellies” are macroscopic, blue-green algal masses whose excessive mucilage of high consistency acts as substrata for other epiphytic components viz. diatoms and green algae. They are more abundant in the lentic areas of the lake, undergo diurnal vertical movements and have their growth enhanced by spikes of nitrogen and phosphorus salts into their aquatic medium. The effects of these “jellies” on the ecology and general water use of the lake are discussed. Speculations on the reasons for their occurrence are given and possible control measures outlined. 相似文献
16.
Leanne T. Nash 《American journal of primatology》1983,5(3):181-196
The reproductive patterns (birth seasonality, litter size, litters per year) of two sympatric species of galago (Galago zanzibaricus and G. garnettii) were studied in a coastal forest in Kenya for a two-year period. Trap-retrap and radio tracking methods were employed. G. zanzibaricus has one infant twice per year; G. garnettii has one infant once per year. Both species are seasonal breeders. These East African galagos are intermediate in reproductive patterns when compared with galagos from South African woodland (G. senegalensis moholi and G. crassicaudatus umbrosis) and West African rainforest (G. alleni and G. demidovii). Climatic patterns (total annual rainfall, seasonal variability of rainfall, variability in total annual rainfall, and annual temperature variability) are also compared for the three regions. Climatically, East Africa is intermediate between West and South Africa in total annual rainfall and in seasonality of rainfall, but not in year-to-year variability in rainfall. East Africa shows the highest variability in annual rainfall. South Africa has the coldest dry seasons and highest variability in temperatures. The results of this study suggest that “r-selection” and “K-selection” do not provide adequate explanations of galago reproductive patterns. 相似文献
17.
CELINA ROITMAN ISAAC ROITMAN HELIO PEIXOTO de AZEVEDO 《The Journal of eukaryotic microbiology》1972,19(2):346-349
SYNOPSIS. A defined medium for an insect trypanosomatid, “Leptomonas pessoai” (probably a member of the genus Herpetomonas) isolated from the reduviid Zelus leucogrammus, allows growth up to 37 C. No marked differences were evident for growth at 37 C. The requirements for amino acids, vitamins, purine, and hemin, and pH range were like those established for Crithidia fasciculata. Again like C. fasciculata, it remains alive at 4 C for at least 3 months in a çlycerolated defined medium. 相似文献
18.
“Bryndza” is a traditional Slovak dairy product (type of soft cheese) made from sheep cheese which was ripened for 14 days. Because its manufacture, transporting and/or storing represent conditions which facilitate contamination, the effect of enterocin CCM4231 in “bryndza” was investigated with the aim to reduce the contaminant agents. “Bryndza” was divided into equal portions (50 g). The experimental sample (ES) as well as the control sample one (C1) were inoculated with Listeria innocua Li1 strain. The other control samples C2 and C3 were without Li1 strain. C3 control was selected as a reference control. ES and C2 portions were treated with purified enterocin CCM4231 in a concentration of 6400 AU/ml. Before the experimental inoculation, “bryndza” was checked for the presence of contaminant agents. The experiment lasted 1 week and the samples were stored in the refrigerator at 4 °C. Sampling was performed on day 1, on day 4 and on day 7. The control samples C2 and C3 were checked only on day 1 and then after 1 week. The following contaminant agents were detected in “bryndza” before its experimental inoculation with L. innocua Li1 strain: Escherichia coli in the amount 103 cfu/ml/g, Staphylococcus aureus (102 cfu/ml/g) and enterococci (104 cfu/ml/g). In the control sample C2, the number of E. coli was reduced to 102 cfu/ml/g. Enterococci and staphylococci were totally eliminated there. Concerning C3 control, natural decrease of bacteria was found and/or their unchanged counts. The value of pH (5) was stable during the whole experiment. In the experimental sample inoculated with Li1 strain, its counts were decreased immediately after enterocin CCM4231 addition approximately by one order of magnitude. This inhibitory effect was also detectable on day 4 by the difference of one order of magnitude between ES and C1. On day 7, 103 cfu/ml/g of Li1 strain were detected in both samples (ES, C1). The difference by one order of magnitude indicated, an inhibitory effect of enterocin CCM4231 in “bryndza”. However, bacteriocin activity was not determined by laboratory analyses. 相似文献
19.
Experiments were conducted to see whether the cellular response to electromagnetic (EM) fields occurs through a detection process involving temporal sensing. L929 cells were exposed to 60 Hz magnetic fields and the enhancement of ornithine decarboxylase (ODC) activity was measured to determine cellular response to the field. In one set of experiments, the field was turned alternately off and on at intervals of 0.1 to 50 s. For these experiments, field coherence was maintained by eliminating the insertion of random time intervals upon switching. Intervals ≥ 1 s produced no enhancement of ODC activity, but fields switched at intervals ≥ 10 s showed ODC activities that were enhanced by a factor of approximately 1.7. These data indicate that it is the interval over which field parameters (e.g., amplitude or frequency) remain constant, rather than the interval over which the field is coherent, that is critical to cellular response to an EMF. In a second set of experiments, designed to determine how long it would take for cells to detect a change in field parameters, the field was interrupted for brief intervals (25–200 ms) once each second throughout exposure. In this situation, the extent of EMF-induced ODC activity depended upon the duration of the interruption. Interruptions ≥ 100 ms were detected by the cell as shown by elimination of field-induced enhancement of ODC. That two time constants (0.1 and 10 s) are involved in cellular EMF detection is consistent with the temporal sensing process associated with bacterial chemotaxis. By analogy with bacterial temporal sensing, cells would continuously sample and average an EM field over intervals of about 0.1 s (the “averaging” time), storing the averaged value in memory. The cell would compare the stored value with the current average, and respond to the EM field only when field parameters remain constant over intervals of approximately 10 s (the “memory” time). Bioelectromagnetics 18:388–395, 1997. © 1997 Wiley-Liss, Inc. 相似文献
20.
Pseudomonas tolaasii, causing brown blotch disease on cultivated mushrooms, and yielding a white line precipitate towards P. “reactans”, has been shown to induce lysis of erythrocytes. Some Finnish strains isolated from diseased mushroom fruit bodies, although harboring the typical features of P. tolaasii, proved to be distinct, and have been allocated to a nov. sp. P. costantinii. We examined in these study whether all brown blotch causing agents were hemolytic. The induction of erythrocytes lysis seemed to be a rather common feature of mushroom associated-pseudomonads, especially for strains involved in the production of a white-line-in agar. 相似文献