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Molecular Hybridization (molecular + hybridization)
Selected AbstractsDETECTION OF SALMONELLA TYPHIMURIUM IN OYSTERS BY PCR AND MOLECULAR HYBRIDIZATIONJOURNAL OF FOOD QUALITY, Issue 5 2006A.A. CORRÊA ABSTRACT Because shellfish (oysters, clams and mussels) are filter feeders, i.e., able to concentrate pathogens from the surrounding waters within their tissues, they have been widely associated with outbreaks illness. The incidence of salmonellosis caused by the consumption of raw or undercooked shellfish, is a primary concern of public health agencies. Then, in recent years, more rapid and specific methods based on the DNA sequence of salmonella genes have been developed to detect low levels of pathogens in environmental and food samples. In this study, we developed a sensitive method to detect low levels of Salmonella typhimurium in oyster tissues (0.1 cfu/g). This methodology consisted of dissection of the gastrointestinal oyster tract, pre-enrichment of the samples in nonselective medium, DNA extraction and polymerase chain reaction followed by molecular hybridization using a digoxygenin-labeled amplicon-derived probe. These results can benefit the public health agencies and shellfish producers concerning microbiological and quality aspects of the commercial oyster production. [source] Sensitive and Specific Digoxigenin-labelled RNA Probes for Routine Detection of Citrus tristeza virus by Dot-blot HybridizationJOURNAL OF PHYTOPATHOLOGY, Issue 6 2006L. Barbarossa Abstract A non-radioactive dot-blot hybridization assay for the successful detection of Citrus tristeza virus (CTV) RNA in total nucleic acid extracts of infected citrus was developed. Two digoxigenin (DIG)-labelled minus-sense riboprobes, complementary to the coat protein gene sequence of a Chinese and an Apulian CTV isolate were synthesized. Several citrus tissues were evaluated as optimal virus source and leaf petioles were found appropriate material for reliable detection. The hybridization assay showed a detection limit corresponding to 0.2 mg of fresh infected tissue. The riboprobes allowed CTV detection in isolates from different geographical areas, grown in the screenhouse or in the field, resulting in similar hybridization patterns. The infected trees were tested during different seasons with positive results, although from July to August most of the samples gave a weaker hybridization signal, compared to other seasons. The high sensitivity and reliability of the molecular hybridization assay described make it a good alternative to serological methods for CTV detection. [source] Differential patterns of morphological and molecular hybridization between Fraxinus excelsior L. and Fraxinus angustifolia Vahl (Oleaceae) in eastern and western FranceMOLECULAR ECOLOGY, Issue 11 2006J. F. FERNANDEZ-MANJARRES Abstract We examined large-scale patterns of morphology, genetic structure and ecological correlates of Fraxinus excelsior and the closely related species Fraxinus angustifolia in France, in order to determine the degree of hybridization between them. We sampled 24 populations in two putative hybrid zones (Loire and Saône), and five control populations of each species. We measured foliar characteristics of adult trees and used five nuclear microsatellites as molecular markers. Canonical discriminant analysis indicated that the two species differ in morphology, but that intermediate types are common in the Loire region but less frequent in the Saône region. Bayesian population assignment identified one F. angustifolia and two F. excelsior gene pools. Most Loire individuals clustered genetically with the F. angustifolia gene pool. In contrast, the Saône region presented individuals belonging mostly to F. excelsior pools, although the F. angustifolia type was frequent in certain populations. The lowest FST values were found between the Loire and F. angustifolia controls that also exhibited no significant isolation by distance. The proportion of the F. angustifolia gene pool in each locality was negatively correlated with winter temperatures, suggesting that a cold climate may be limiting. Hybridization is probably favoured by the intermediate climatic conditions in the Loire region that allow both species to occur, but is somewhat hampered by the harsher winters in the Saône area where morphological introgression has apparently not yet occurred. [source] Let them fly or light them up: matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry and fluorescence in situ hybridization (FISH),APMIS, Issue 11-12 2004BIRGITTA SCHWEICKERT This review focuses on clinical bacteriology and by and large does not cover the detection of fungi, viruses or parasites. It discusses two completely different but complementary approaches that may either supplement or replace classic culture-based bacteriology. The latter view may appear provocative in the light of the actual market penetration of molecular genetic testing in clinical bacteriology. Despite its elegance, high specificity and sensitivity, molecular genetic diagnostics has not yet reached the majority of clinical laboratories. The reasons for this are manifold: Many microbiologists and medical technologists are more familiar with classical microbiological methods than with molecular biology techniques. Culture-based methods still represent the work horse of everyday routine. The number of available FDA-approved molecular genetic tests is limited and external quality control is still under development. Finally, it appears difficult to incorporate genetic testing in the routine laboratory setting due to the limited number of samples received or the lack of appropriate resources. However, financial and time constraints, particularly in hospitals as a consequence of budget cuts and reduced length of stay, lead to a demand for significantly shorter turnaround times that cannot be met by culture-dependent diagnosis. As a consequence, smaller laboratories that do not have the technical and personal equipment required for molecular genetic amplification techniques may adopt alternative methods such as fluorescence in situ hybridization (FISH) that combines easy-to-perform molecular hybridization with microscopy, a technique familiar to every microbiologist. FISH is hence one of the technologies presented here. For large hospital or reference laboratories with a high sample volume requiring massive parallel high-throughput testing we discuss matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF) of nucleic acids, a technology that has evolved from the post-genome sequencing era, for high-throughput sequence variation analysis (1, 2). [source] | ||||||||||