Taxonomic Study Of Two Trichuris Spp. From Different Hosts By Morphological And Molecular Biological Methods

The adults of Trichuris spp. were obtained from Hamadraya Baboon(Papio hamadryas) and Squirrel Monkey (Saimiri sciureus) in the Zoo ofChongqing city. Morphological and molecular biological study werecarried on the adults of Trichuris spp. from the two different source fortaxonomy. Firstly, the two different Trichuris spp. adults were identified bymorphological methods. Data (includ the length of spermaductus,ejaculatory duct, cloaca, length between initiation of cloaca and theconfluence spot of cloaca and spicule-duct, etc) were acquired bymicroscopic meter measuring. The two species of Trichuris were identifiedaccording to the data of other well-defined Trichuris species. Then,Genomic DNA of the two Trichuris spp. adults was isolated, and the ITS2segment from the ribosomal DNA (rDNA) was amplified by polymerasechain reaction (PCR), and the amplified products were sequenced. TheITS2 sequences of the two species of Trichuris were compared with thoseof other six trichuris species by DNA sequence analysis tool DNAMAN.The endonucleases Mspâ… and Haeâ…¢ were chosen for the PCR-linkedRFLP analysis of ITS2 and restriction maps were determined. According to the morphological analysis, we found Trichuris spp.from Hamadraya Baboon should be T.cynocephalus, but Trichuris spp.from Squirrel Monkey, which probably is T. rhinopiptheroxell-a sp.novcould not be determined because there were not enough amount of adultwroms (10 individual nematodes needed at least). The morphologicaldifferences between the two species of Trichuris had been detecteddefinitely. The ITS2 sequence of Trichuris spp. from Hamadraya Baboonwas 605bp in length, with a GC content of 63.47%. The ITS2 of Trichurisspp. from Squirrel Monkey was 621bp in length, with a GC content of62.80%. The differences were detected between the two sourced Trichurisspp. by their ITS2 sequences. ITS2 sequences of these two Trichuris spp.were longer than those of other six species of Trichuris, but the GCcontents of the two species were close to those of the other six speciesTrichuris. The ITS2 sequences of these species of Trichuris were compared,and the results indicated the variation was more than intraspecific variation.Therefore, we found that the two sourced Trichuris spp. should be differentfrom the other six determined species. The identity between the twodifferent sourced Trichuris spp. was 46.98%, which was higher than otherpairs comparisions, except Trichuris suis and Squirrel Monkey sourcedTrichuris spp. (51.8%). The difference was detected in PCR-linkedrestriction-fragment-length-polymorphism (RFLP) maps, which indicatedthat RFLP restriction maps could reliably differentiate the two sourcedTrichuris spp. . Based on ITS2 sequences of the eight Trichuris species, aphylogenetic tree was constructed. In conclusion, Trichuris spp. from Hamadraya Baboon could beidentified as T. cynocephalus, Trichuris spp. from Squirrel Monkey couldpossibly be identified as T. rhinopiptheroxell-a sp.nov. The two species ofTrichuris have obvious differences in morphology; ITS2 sequences of thetwo species of Trichuris are acquired. Differences of ITS2 sequences weredetected between the two sourced Trichuris spp. , which means that theybelong to two different species from the other six species; a phylogenetictree based the ITS2 sequence of the eight species was constructed.