Study On Polymorphism Of RDNA And MtDNA Of The Nematodes Trichuris Trichiura And T. Suis

Genus Trichuris(Aphasmidea:Trichurada:Trichuridae)as an intestinal infection parasitic disease that can be seen much more common on human and animal.According to records,Trichuris suis can also infect human.With constant evolution and development of the population,particularly those of similar or related species,the morphological identification of parasites increasingly shows its limitations.In particular,in recent years,the parasites PCR technology in the molecular taxonomy,molecular genetics,species(strains) identification of the research has achieved great success,such as the PCR amplification reaction-based restriction fragment length polymorphism(PCR-RFLP),random amplified polymorphic DNA(RAPD)and single strand conformation polymorphism(SSCP)analysis.This study is the first-time to study Trichuris that come from different host and different parts of China.The internal transcribed spacer sequences(ITS)and mitochondria(mtDNA)such as large subunit gene(lsrRNA),NADHâ…£dehydrogenase subunit gene(nad4)through PCR amplification,cloning and sequence analysis.The results:ITS-1 sequences length of T.suis are 655-661 bp,and ITS-2 sequence are 530-538 bp;ITS-1 sequences length of T.trichiura are 600-627 bp,and ITS-2 sequence are 468-486 bp; both the 5.8 S sequences are 154 bp.There are 14 different base pairs in ITS-1 sequence of Trichuris suis between China and Spain,the difference is 2.1%;18 different base pairs in ITS-2 sequence,the difference is 3.4%;1 different base pair in 5.8 S sequence,the difference is 0.6%.There are 34 different base pairs in ITS-1 sequence of T.trichiura,the difference is 5.4%;34 different base pairs in ITS-2 sequence,the difference is 6.4%.There are 15 different base pairs in ITS-1 sequence of T.suis,the difference was 2.3%;13 different base pairs in ITS-2 sequence,the difference was 2.4%.The difference in ITS-1 sequence between T.trichiura and T.suis up to 45.1%,and in ITS-2 sequence up to 74.7%.There are six different base pairs in 5.8 S sequence,difference is 3.9%.Microsatellite repeat sequences can be seen in T.suis (ITS-1:AGC,CGC;ITS-2:GCT,CG,C),in T.trichiura(ITS-1:CAG,GGC;ITS-2:CAG,CGA,CGG, GCG).Delete microsatellite repeat sequence in ITS-1 and ITS-2 sequence,there are 10 different base pairs in ITS-1 sequence of T.trichiura,the difference is 1.7%.In ITS-2 sequence,five different base pairs,the difference is 1.1%.There are 9 different base pairs in ITS-1 sequence of T.suis,the difference was 1.4%;in ITS-2 sequence,9 different bases,the difference is 1.8%.Related GeneBank database were downloaded(accession number:AY851266;Trichuris.ovis, AJ238220;T.leporis,AJ251321;T.skrjabini,AJ489248;T.vulpis,AM234616;T.arvicolae,AJ310661;T. muris,AJ299407).ITS-2 gene fragments of the Trichinella spiralis as a out-group(accession number: AY851266),using Neighbor Joining method of PHYLIP(version 3.67),as well as maximum parsimony method of PAUP(version 4.0b4a).Confidence levels for each grouping were calculated with a bootstrap program(SEQBOOT)in the PHYLIP package,with a total of 1000 replicates.The trees were produced by application of the CONSENCE program of the PHYLIP package.Even though the result of phylogenetic analysis showed a high degree of similarity between T. trichiura and T.suis.Ultimately,the resolution of the question as to whether the two taxa represent separate species requires reciprocal cross-mating experiments to be conducted,using appropriate controls, to determine the extent of mating and the reproductive capabilities of any "hybrid" individuals produced. Only if cross-mating experiments could provide an answer to the question as to whether they represent the same or different species.