| PrefaceThe cestodes parasiting in humans include Taenia solium , Taeni-a saginata , Echinococcus granulosus and Hymenolepis nana, etc. , a-mong which T. solium and T. saginata are the two most common ones, causing porcine and bovine cysticercosis and taeniasis in humans. In addition, T. solium eggs can infect humans, often giving rise to fatal neurocysticercosis. These cestodes are therefore a global economic impact through morbidity and mortality in humans and production losses in domestic stock , which makes the study on them become one of the hot research topics. The identification and classification of the pathogens are the premises of all kinds of delicate study.As we have more knowledge of the parasite populations, we realized the conventional methods for classification and identification are somewhat limited. For example, T. solium and T. saginata are difficult to differentiate by parasitological examination because their eggs are indistinguishable. Differentiation of the two human Taenia species is based on the number of uterine branches present in well - preserved gravid proglottids or on the absence or presence of hooks in the scolex of the tapeworm. Obtaining well ?preserved and intact gravid proglottids or the scolex after treatment of the patient is often difficult due to the partial destruction of gravid proglottids or the recovery of only im-mature proglottids in the stool. In recent years, such a method as genie analysis has been used in this field by detecting the polymorphic DNA and is considered more reliable than those based on morphology. DNA hybridization techniques have been used to differentiate between T. solium and T. saginata by Rish and Harrison. However, hybridization is best performed with radioactive probes , which are expensive, are difficult to handle, and require special equipment. PCR is a more easily performed assay for the identification of these two cestodes. But it requires target DNA sequence information for the design of amplification primers, which is a complex task because a genomic library has to be constructed. Besides, both the assays can be used only in identification and can not tell the phylogenetic relatives of the detected species.Random Amplified Polymorphic DNA analysis (RAPD) is a new molecular marker developed by Welsh and William in 1990. It is based on the amplification of genomic DNA with single primers of ar-bitary nucleotide sequence and is a useful technique for molecular genetic identification of species and the examination of genetic diversity in populations. This technique is easy to perform and requires a small amount of DNA and no prior sequence information . No study has been known on cestodes using the RAPD technique. In the present study we applied RAPD technique to genomic DNA of Taenia solium , Taenia saginata and Hymenolepis nana so as to examine its utility for the classification and identification of cestodes as well as the differentiation of the two human taeniid species.MethodsGenomic DNA from Taenia solium , Taenia saginata , and Hym-enolepis nana was amplified by the polymerase chain reaction using decanucleotide primers and their compound ones. The amplified products were separated on 1.2% agarose gel, stained with ethidium bromide, and photographed under U. V. transillumination. The 200bp DNA Ladder Marker was used as molecular size standards. The size of random amplified DNA fragment was estimated by the Gelworks 1D Intermediate software. According to the popular statistical method for RAPD, the data of our study was processed as the following: First, the species - specific RAPD profiles were used as molecular markers of each cestode species. Second, similarity indices between the detected individuals were calculated according to the Neis formula followed by cluster analysis using the unweighted pair groups average linkage analysis (UPGMA) in SAS6.04 software.ResultsIn this study, ten single primers were applied to amplify the ge-nomic DNA from Taenia solium , Taenia saginata , and Hymenolepis nana...
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