Study On The Sequence And Secondary Structure Of Haplorchis Taichui 5.8S RRNA From Guangxi

OBJECTIVE:The The sequence and secondary structure of Haplorchis taichui from Guangxi and other Digenea Trematodes 5.8S rRNA are investigated to explore the kinships of Haplorchis trematodes and the secondary structure characters of Digenea Trematodes 5.8S rRNA.METHODS:Haplorchis taichuis were collected from Fusui county in Guangxi.The genomic DNA of Haplorchis taichui from Guangxi was extracted. The 5.8S rDNA was amplified by PCR and the sequences of PCR products were obtained by the sequencing reaction The 5.8S rDNAs of Haplorchis taichui,Haplorchis pumilio,Fasciola gigantica,Schistosoma sp,Isthmiophora melis,Echinostoma revolutum,Opisthorchis felineus from Genebank were investigated too.The 5.8S rDNAs of the above Trematodes are all transformed into the 5.8S rRNAs.The secondary structure of the 5.8S rRNAs were constructed using RNAstructure3.2 software according to the theory of minimally free energy with Zuker method.The composition of the sequence structures and the secondary structures of the 5.8S rRNAs were analyzed with SPSS v14.The sequences and secondary structures of Digenea Trematodes 5.8S rRNA were compared to explore their characters.RESULTS:Sequence comparing was performed between the 5.8S rRNA of Haplorchis taichui from Guangxi and that previously studied by Dzikowski,with the results showing some point mutations sites in the 81th, 83nd,84th,129th and 143th nucleotide.Those sites locate in unpaired regions so that they don't affect on the secondary structural characters of the 5.8S rRNA. Sequence comparing between Haplorchis taichui from Guangxi and Haplorchis pumilio showed mutation sites which not only locate in unpaired regions but also in pared regions.The mutationof the nucleotides locating in pared regions cause more differences in 5.8S rRNA secondary structures between Haplorchis taichui from Guangxi and Haplorchis pumilio.The secondary structures of 5.8S rRNA in several Digenea Trematodes are all composed of main structure models. Branchâ… has one conservative motif,5'-GUGUCGAUG:CAUCGACAU-3' (5'-GUGUCGAUG:CAUCGAUAU-3' in Haplorchis pumilio).Branchâ…¡has a conservative hairpin,which consists of nine basepairs5'-GGCCAUGGG: CCUGUGGCC-3'(5'-GGCUACGGG:CCUGUGGCC-3' in Schistosoma sp) The hairpin loop is a six-membered ring of U rich.There is a single strand sequence in the 5' end of 5.8S rRNA among the above Trematodes except Schistosoma sp and Opisthorchis felineus.The Trematodes except Haplorchis taichui have a conservative motif(5'-GCAG:CUGC-3')in branchâ… . Haplorchis taichui and Schistosoma sp have a different handle and multibranch loop,compared with other six Trematodes.The branchâ… end of Fasciola gigantica,Isthmiophora melis and Echinostoma revolutum have a conservative hairpin.Replacement,deletion and insertion of bases mostly occur in the single strand region of the secondary structure of the 5.8S rRNAs.While these occurre in double strand,the secondary structure changes tremendously.CONCLUSION:It was the first time that this study had obtainded 5.8S rRNA gene sequence of Haplorchis taichui from Guangxi.The secondary structure characters of 5.8S rRNA were discovered in Digenea Trematodes. According to their secondary structure characters of 5.8S rRNA,the kinship between Haplorchis taichui from Guangxi and that previously studied by Dzikowski is nearer while the kinship between Haplorchis taichui from Guangxi and Haplorchis pumilio is more far away.