The Phylogeny And Sequence Analysis On Three Species Of Coronocyclus

There are a wide range of species belonging to parasitic nematodes.They make a living by absorbingdigesta, intestinal tissues,body fluids or blood of hosts by the digestive tract. It can lead to physicaldisorders of hosts because of anemia.Some species excrete toxins that damage organal functions. Diseasescausing by parasitic nematodes have a long period due to the complex life history, weaken immunity ofhuman or animal body, and affect the growth and even development of hosts. Many different speciessimultaneously parasitize in the same host, increasing the treatment difficulty. Hence, the research is veryimportant for different parasitic nematodes, which will lay the theoretical groundwork for thediagnosis,identification, prevention and control of various nematode,and ensure the healthy developmentof animal husbandry and manufacture and living fields of human being society. There are many reports onthe classification of parasitic nematodes, life history, epidemiological, phylogenetic studies using modernmolecular technology and other studies abroad. In our country, it lacks classification analysis usingmolecular technology for parasitic strongyloid; through there are some reports about morphological andmolecular classification. This paper is the first report about classification analysis molecular technologyand phylogeny for Coronocyclus in the large intestine of donkeys in Henan Province in detail.In this experiment, internal transcribed spacer(ITS) and5.8S sequence of rDNA of the adults of threekinds of Coronocyclus(C. coronatus,C. labiatus,C. labratus) were amplied, using the conservative primersNC5and NC2by polymerase chain reaction (PCR) technique, purified and sequenced. The sequencingresults showed that the ITS and5.8S sequence had a total length of748-843bp, Including367-370basepairs of ITS1,153base pairs of5.8S and228-320base pairs of ITS2. The variable sites(including deletion)and parsimony informative sites are119bp and18bp in the total ITS correspondingly,14bp and9bp in ITS1and105bp and9bp in ITS2. G+C conten (48.00-48.50%) in the ITS-1was significantly higher than in theITS2(37.70-40.30%) by sequence composition analysis.The analysis showed that the interspecific differences are1.89-2.71%in ITS1and5.66-31.88%inITS-2among five sequences. At the same time, the five sequences were submitted to Genbank, andaccession numberas are JN786948-JN786951. The range of intraspecific differences is0-0.83%. Thedegree of interspecific variation is greater than the one in intraspecific variation, indicating that the ITSsequences can be used as reliable molecular genetic markers in the identification of Coronocyclus nematodes. Based on ITS sequences of three species of the genus Coronocyclus, neighbor-joining (NJ) treeand maximum-parsimony (MP) tree were constructed using Cylicostephanus minutus as outgroup utilizingMEGA5.0(Molecular Evolutionary Genetics Analysis.5.0version) software. The results showed that,three kinds of Coronocyclus (C. coronatus,C. labiatus,C. labratus) always clustered into a branch singly,in case there were more than one haplotype and samples were from different geographic regions. Moreoversamples of C. labiatus and C. labratus always gathered in a larger branch, indicating that the two had acloser relationship. The same result was displayed by the smaller genetic distance between C. labiatus andC. labratus from table6. Samples of C. coronatus, was clustered into another branch, indicating that it hada distant genetic relationship comparatively.