Epidemic Characteristics Analysis,Species Taxonomy Identification And Phylogenetic Analysis Of Diplostomum In Irtysh River

Diplostomum is a kind of fish parasites which with small in body size and diversity morphological.With complicated life history,it replaces host in different period of larva.Diplostomum is a preponderance trematode in the Irtysh River that parasitic cause lens turbidity and damage organization structure of the eyes.When Diplostomum invade of fish,the migration process of Diplostomum would cause mechanical harm and lead to secondary infection,which results in the explosion of bacterial diseases.Serious explosion of paragonimiasis can also diretly lead to the death of fish.The research takes host of Diplostomum such as Perca Linnaeus and snail in Irtysh River as subjects,by statistical means for epidemiology,morphology,taxonomy and biology,we define Diplostomum species,research on phylogeny and analyze on codon preference as well as clarify Diplostomum population related scientific problems of Irtysh River,Xinjiang so as to provide theoretical evidence to comprehensive prevention and therapy of fish diseases.（1）By dection statistics for Perca Linnaeus in 486 sampling of 6 locations in Irtysh River,we get the total infection rate of Diplostomum from Perca fluviatilis,Lucioperca lucioperca and Acerina cernua are51.38%、71.33%、35.42%.Referring to“The ichthyography of Xinjiang”,we conduct statistic analysis on4 body length groups classified based on fish age.There are differences infection quantity of lens and vitreum in Perca fluviatilis,Lucioperca lucioperca and Acerina cernua in different body length groups.According to distribution pattern,we judge that population is aggregated distribution.Diplostomum has obvious selectivity on L _e,L_v,R _e,R_v in Perca Linnaeus,Diplostomum has rich species and complex species quantity.（2）According to morphological classification research method for trematoda,we select 16 structure measuring parameters with morphological features of metacercaria:body length（BL）,body width（BW）,oral sucker length（OSL）,oral sucker width（OSW）,ventral sucker length（VSL）,ventral sucker width（VSW）,adhesive length（BOL）,adhesive width（BOW）,BW/BL,BW×BL,OSW/OSL,OSW×OSL,VSW/VSL,VSW×VSL,BOW/BOL,BOW×BOL.The research records and describes 4 kinds of metacercaria:Diplostpmum spathaceum,Diplostomum pseudospathaceum,Tylodelphys spp.and Tylodelph-ys clavata,applies statistic analysis to prove the significant difference of the morphological structure between the 4 kinds of metacercaria.（3）Illustrate research on species identification and classification of Diplostomum in Perca Linnaeus through mitochondrion COI gene.The research measured sequence of 2 kinds of Diplostomum.By GenBank comparison,N1,N2 respectively are D.spathaceum and T.clavata,the homology rate respectively are 99.4%（17/621）and 97.3%（604/621）.N1 clusters with Iraq KR271465.1 and KR271440.1as one branch and the supportive rate is 99;N2 clusters with KR271475 and the supportive rate is 99.（4）Apply morphological and genetic marking technology to determine 2 kinds of cercaria from Diplostomum.There are 11 morphological measuring parameters:Body length（BL）,body width（BW）,body front（AOL）,central body（AOW）,tail length（TSL）,tail width（TSW）,oral sucker length（OSL）,oral sucker width（OSW）,ventral sucker length（VSL）,ventral sucker width（VSW）.Refer to such parameters and combining with mitochondrion COI gene for PCR identification.The result shows that the two cercaria species are Diplostomum mergi and T.clavata.The identification results from GenBank comparison,genetic distance calculation and phylogenetic analysis on the sequence are consistent.By RSCU and compositional deviation analysis,we get that the use rate of synonymous codon of the Diplostomum is different and is characterized by preference.D.mergi is the parasite which has only one host while T.clavata has multiple hosts.From this,we can deduce that the phenomenon is closely related to the regional characteristics of the Irtysh River,difference of host foraging,and immunological characteristics of host.