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Food adulteration means that substances have been added to food that change its composition and reduce its nutritional value. Food adulteration also includes giving a product a misleading name, providing false information on its composition, date of production or expiry date, and any other incorrect labelling. Numerous cases of food adulteration have been recorded in many countries, including Poland. This has led to the creation of a new field of science, known as ‘green criminology’, to combat violations of food law. Over the years, new techniques for identifying food adulterations have been developed. Originally, these were sensory techniques, which proved unreliable. Later, physical analysis of the product was performed on the basis of information on the label and microscopic examination. Later methods, based on identification of lipids and proteins, were also unreliable due to biochemical changes during processing. These problems prompted scientists to become interested in the potential of DNA testing. Due the stability of DNA and the universal applicability of DNA-based methods to all cells, they are ideal for use in practice. Currently, the most reliable test for detecting food adulteration is PCR, as it is a highly sensitive and specific technique.
Molecular techniques were employed to document the microbial diversity associated with the marine sponge Pachychalina sp. from South China Sea in March 2003. Using the total microbial DNA as template, bacterial and archaeal 16S rDNAs were amplified by PCR with universal primers. Amplified products were cloned, sequenced and secondarily amplified by PCR. Then the secondarily amplified products were purified to be further characterized by amplified rDNA restriction analysis (ARDRA). According to the enzyme restriction mapping, the apparent difference among them were disclosed. 22 bacterial cloned partial sequences were acquired and most of them were related to proteobacterium. Also, 7 archaeal cloned partial sequences were acquired and a phylogenetic tree was built up.Result shows the prolific bacterial and archaeal diversity of marine sponge Pachychalina sp.
The aim of this article is to give an overview of the molecular methods used for detecting helminth parasites in the environment, their advantages as well as their limitations with examples of successful applications of these methods in different helminth classes. Molecular techniques represent a wide range of sensitive diagnostic tools in parasitology. Environmental monitoring is an essential element of epidemiological studies. Many helminth parasites depend on the environment for the completion of their life cycle. The abundance of their transmissive stages determines infection risks. The application of highly specific and sensitive monitoring methods allows gathering more precise epidemiological data.
The application of random amplified polymorphic DNA- polymerase chain reaction (RAPDPCR) was found to be a simple, cheap and rapid tool to discriminate human pathogenic bacterial isolates especially at intraspecific level. This molecular biological technique relies on the use of random oligonucleotide primers that arbitrarily amplifies specific regions of the genome which gives rise to a unique genomic fingerprint of the strains under investigations. With continued development of novel molecular-based technologies for rapid, high-throughput detection of food borne pathogenic bacteria, the future of conventional microbiological methods such as viable cell enumeration, selective isolation of bacteria on commercial media, and immunoassays seems tenuous. Approaches that enhance recovery of sub lethally injured bacteria, differentiation among species, differentiation among bacteria of interest using biochemical profiling, enumeration using impedance technology, techniques to confirm the presence of target pathogens using immunological methods, and bioluminescence applications for hygiene monitoring are of utmost need in identifying and combating the human pathogenic isolates. The aim of this study is to estimate the efficiency of RAPD-PCR technique in assessing the genetic diversity of diseases causing bacterial isolates. The use of RAPD-PCR in evaluating the genomic variability among the pathogenic strains belonging to different genus are also been discussed in the present report.
In this study the pathogenicity of Rhizoctonia spp. isolates towards wheat seedlings in laboratory and greenhouse conditions was evaluated. In both experiments seven features were examined: plant height, roots weight, the percentage of infected stems and leaf sheaths and also the degree of stem and leaf sheaths infection. Isolates R1, R29, R39 and R59 were the most pathogenic. Percentage of infected stems ranged from 25.3 to 82.5 and roots from 35 to 82.3. The amplification of internal transcribed spacer regions (ITS1 and ITS2) between 18S, 5.8S and 28S rRNA genes and sequence analysis of these regions have been shown to be sufficiently variable to resolve two Rhizoctonia species. Random amplified polymorphic DNA (RAPD) was used to assess genetic variability among isolates. The suitability of RAPD method for isolates differentiation at intraspecific level was shown. Using seven arbitrary primers in polymerase chain reaction (PCR) thirty-three RAPD markers were generated. Clustering analysis from RAPD data resolved two groups of R. cerealis isolates at the 36% similarity level. Moreover, significant associations between molecular markers and pathogenicity of R. cerealis isolates were found.
Spores of many fungal pathogens are dispersed by wind. Detection of these airborne inocula is important in forecasting both the onset and the risk of epiphytotics. Species-specific primers targeted at the internal transcribed spacer (ITS) region of Leptosphaeria maculans and L. biglobosa - the causal organisms of phoma stem canker and stem lesions of Brassica spp., including oilseed rape - were used to detect DNA extracted from particles deposited on tapes obtained from a spore trap operated in Rarwino (northwest Poland) from September to November in 2004 and 2006. The quantities of DNA assessed by traditional end-point PCR and quantitative real-time PCR were compared to microscopic counts of airborne ascospores. Results of this study showed that fluctuations in timing of ascospore release corresponded to the dynamics of combined concentrations of DNA from L. maculans and L. biglobosa, with significant positive correlations between ascospore number and DNA yield. Thus the utilization of PCR-based molecular diagnostic techniques enabled the detection, identification, and accurate quantification of airborne inoculum at the species level. Moreover, real-time PCR was more sensitive than traditional PCR, especially in years with low ascospore numbers.
Chalkiness is a major constraint on rice production because it is one of the key factors determining grain quality (appearance, processing, milling, storing, eating, and cooking quality) and price. In this study, we conducted grain chalkiness gene identification using co-dominant insertion/deletion (INDEL) markers and SSR marker combination on 50 different varieties. The application results in 7 InDel markers and SSR marker on chromosome 7 were recorded. Three primers, InDel 5, InDel 14 and RM21938, associated with grain chalkiness. For the InDel 5 primer, the amplification product was 100%. Use of primer InDel 5 in detection and evaluation of genotype to the chalkiness trait of rice grain on 50 rice varieties indicated the suitability level with phenotypic evaluation was 86% and the unsuitability level was 14%. For the InDel 14 primer, the amplification products were 100%. The suitability with phenotypic assessment was 84% and the unsuitability was 16%. For the RM21938 primer, the amplification product was 94%. The suitability with phenotypic assessment was 76% and the unsuitability was 24%. Thirteen of the selected varieties had grain chalkiness gene both InDel 5, InDel 14 and RM21938. Total 13 varieties were detected from InDel 5, InDel 14 and RM12938 primer combinations also showed high efficiency of the InDel technique in identifying chalkiness gene in rice grain. A cluster analysis was performed and a dendrogram was constructed which evinced the nature of phylogenetic classification among the genotypes of the varieties. These markers could be used for developing quality of rice in breeding program.
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