Detection of Erysiphe necator in Air Samples Using the Polymerase Chain Reaction and Species-Specific Primers     

Falacy JS  Grove GG  Mahaffee WF  Galloway H  Glawe DA  Larsen RC  Vandemark GJ 《Phytopathology》2007,97(10):1290-1297

ABSTRACT A polymerase chain reaction (PCR) assay employing species-specific primers was developed to differentiate Erysiphe necator from other powdery mildews common in the northwest United States. DNA was extracted from mycelia, conidia, and/or chasmothecia that were collected from grape leaves with a Burkard cyclonic surface sampler. To differentiate E. necator from other erysiphaeceous fungi, primer pairs Uncin144 and Uncin511 were developed to select unique sequences of the internal transcribed spacer regions of E. necator. Using these primers in PCR amplifications, a 367-bp amplicon specific to E. necator was generated, but no amplicons were generated from other erysiphaceous species collected from 48 disparate hosts representing 26 vascular plant families. The PCR limit of detection was one to five conidia of E. necator placed directly into reaction mixtures or 100 to 250 conidia placed on glass rods coated with silicon grease. During field studies, this PCR assay facilitated the detection of E. necator inoculum in air samples within hours of sample rod collection and prior to disease onset. Amplification of E. necator DNA did not occur when the PCR assay was conducted on vineyard air samples collected while grapes were dormant or during periods when vine growth occurred but E. necator remained dormant. The initial PCR detection of E. necator of the season occurred during seasonal ascospore releases caused by precipitation events between bud burst and the prebloom period during the 3 years of the study. Detection ceased for 7 to 11 days following ascospore release and then resumed several days prior to the observance of microscopic symptoms and signs of powdery mildew in the field. Results of this study represent the initial step toward the goal of incorporating an inoculum availability component into current and future grapevine powdery mildew risk assessment models.  相似文献   

Quantitative structure-activity relationships of pine weevil antifeedants, a multivariate approach     

Sunnerheim K  Nordqvist A  Nordlander G  Borg-Karlson AK  Unelius CR  Bohman B  Nordenhem H  Hellqvist C  Karlén A 《Journal of agricultural and food chemistry》2007,55(23):9365-9372

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Immune response to Sarcocystis neurona infection in naturally infected horses with equine protozoal myeloencephalitis     

Yang J  Ellison S  Gogal R  Norton H  Lindsay DS  Andrews F  Ward D  Witonsky S 《Veterinary parasitology》2006,138(3-4):200-210

Equine protozoal myeloencephalitis (EPM) is one of the most common neurologic diseases of horses in the United States. The primary etiologic agent is Sarcocystis neurona. Currently, there is limited knowledge regarding the protective or pathophysiologic immune response to S. neurona infection or the subsequent development of EPM. The objectives of this study were to determine whether S. neurona infected horses with clinical signs of EPM had altered or suppressed immune responses compared to neurologically normal horses and if blood sample storage would influence these findings. Twenty clinically normal horses and 22 horses with EPM, diagnosed by the presence of S. neurona specific antibodies in the serum and/or cerebrospinal (CSF) and clinical signs, were evaluated for differences in the immune cell subsets and function. Our results demonstrated that naturally infected horses had significantly (P<0.05) higher percentages of CD4 T-lymphocytes and neutrophils (PMN) in separated peripheral blood leukocytes than clinically normal horses. Leukocytes from naturally infected EPM horses had significantly lower proliferation responses, as measured by thymidine incorporation, to a non-antigen specific mitogen than did clinically normal horses (P<0.05). Currently, studies are in progress to determine the role of CD4 T cells in disease and protection against S. neurona in horses, as well as to determine the mechanism associated with suppressed in vitro proliferation responses. Finally, overnight storage of blood samples appears to alter T lymphocyte phenotypes and viability among leukocytes.  相似文献   

Prevalence and factors associated with fecal shedding of Giardia spp. in domestic cats     

Vasilopulos RJ  Mackin AJ  Rickard LG  Pharr GT  Huston CL 《Journal of the American Animal Hospital Association》2006,42(6):424-429

The prevalence of cats shedding Giardia cysts (13.6%) in the present study was found to be higher than previously reported (1% to 11%) and may reflect a higher sensitivity for the diagnostic test used. The presence of Cryptosporidium spp. oocysts, coccidial oocysts, and a clinical history of chronic (>2 weeks) gastrointestinal signs were significantly associated with the presence of Giardia spp. cysts in the feces. There were no associations between the presence of Giardia spp. cysts and type of housing, acute gastrointestinal signs, vomiting, gender, source of cat (i.e., animal shelter versus private breeder), or gastrointestinal parasites other than Cryptosporidium spp. and intestinal coccidial agents.  相似文献   

Molecular biology for the clinician: understanding current methods     

Chandler HL  Colitz CM 《Journal of the American Animal Hospital Association》2006,42(5):326-335

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Oceanographic basis of the global surface distribution of Prochlorococcus ecotypes     

Bouman HA  Ulloa O  Scanlan DJ  Zwirglmaier K  Li WK  Platt T  Stuart V  Barlow R  Leth O  Clementson L  Lutz V  Fukasawa M  Watanabe S  Sathyendranath S 《Science (New York, N.Y.)》2006,312(5775):918-921

By using data collected during a continuous circumnavigation of the Southern Hemisphere, we observed clear patterns in the population-genetic structure of Prochlorococcus, the most abundant photosynthetic organism on Earth, between and within the three Southern Subtropical Gyres. The same mechanisms that were previously invoked to account for the vertical distribution of ecotypes at local scales accounted for the global (horizontal) patterns we observed. Basin-scale and seasonal variations in the structure and strength of vertical stratification provide a basis for understanding large-scale horizontal distribution in genetic and physiological traits of Prochlorococcus, and perhaps of marine microbial communities in general.  相似文献   

Progressive disruption of cellular protein folding in models of polyglutamine diseases     

Gidalevitz T  Ben-Zvi A  Ho KH  Brignull HR  Morimoto RI 《Science (New York, N.Y.)》2006,311(5766):1471-1474

Numerous human diseases are associated with the chronic expression of misfolded and aggregation-prone proteins. The expansion of polyglutamine residues in unrelated proteins is associated with the early onset of neurodegenerative disease. To understand how the presence of misfolded proteins leads to cellular dysfunction, we employed Caenorhabditis elegans polyglutamine aggregation models. Here, we find that polyglutamine expansions disrupted the global balance of protein folding quality control, resulting in the loss of function of diverse metastable proteins with destabilizing temperature-sensitive mutations. In turn, these proteins, although innocuous under normal physiological conditions, enhanced the aggregation of polyglutamine proteins. Thus, weak folding mutations throughout the genome can function as modifiers of polyglutamine phenotypes and toxicity.  相似文献   

Selective genotyping to identify late blight resistance genes in an accession of the tomato wild species <Emphasis Type="Italic">Solanum pimpinellifolium</Emphasis>     

Heather L. Merk  Hamid Ashrafi  Majid R. Foolad 《Euphytica》2012,187(1):63-75

Late blight (LB), caused by the oomycete Phytophtohra infestans, is one of the most destructive diseases of tomato (Solanum lycopersicum) and other Solanaceae species. Current disease control and prevention strategies are not sufficient to control the disease in tomato. Recent germplasm screening experiments led to the identification of a new source of resistance (PI 270443) in the tomato wild species S. pimpinellifolium. This study was conducted to identify genomic regions associated with LB resistance in this accession. A large F₂ population (n = 986) derived from a cross between PI 270443 and a LB-susceptible tomato breeding line (NCEBR-2) was screened for LB resistance using a highly aggressive isolate of P. infestans. Twenty-five of the most resistant and 29 of the most susceptible, but surviving F₂ individuals were identified based on disease evaluations conducted in the F₂ and F₃ progeny populations. The selected individuals were genotyped with 153 DNA markers located across the 12 tomato chromosomes. A selective genotyping approach led to the identification of two genomic regions on tomato chromosomes 1 and 10 associated with LB resistance in PI 270443. Identification of two genomic regions associated with resistance was consistent with a previous estimate of the number of LB resistance genes in this accession. Research is currently underway to fine map the two resistance genes and incorporate them into new tomato breeding lines and hybrid cultivars.  相似文献   

Design of stable nanocrystalline alloys     

T Chookajorn  HA Murdoch  CA Schuh 《Science (New York, N.Y.)》2012,337(6097):951-954

Nanostructured metals are generally unstable; their grains grow rapidly even at low temperatures, rendering them difficult to process and often unsuitable for usage. Alloying has been found to improve stability, but only in a few empirically discovered systems. We have developed a theoretical framework with which stable nanostructured alloys can be designed. A nanostructure stability map based on a thermodynamic model is applied to design stable nanostructured tungsten alloys. We identify a candidate alloy, W-Ti, and demonstrate substantially enhanced stability for the high-temperature, long-duration conditions amenable to powder-route production of bulk nanostructured tungsten. This nanostructured alloy adopts a heterogeneous chemical distribution that is anticipated by the present theoretical framework but unexpected on the basis of conventional bulk thermodynamics.  相似文献   

A lineage of myeloid cells independent of Myb and hematopoietic stem cells   总被引：1，自引：0，他引：1  

Schulz C  Gomez Perdiguero E  Chorro L  Szabo-Rogers H  Cagnard N  Kierdorf K  Prinz M  Wu B  Jacobsen SE  Pollard JW  Frampton J  Liu KJ  Geissmann F 《Science (New York, N.Y.)》2012,336(6077):86-90

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