Study On The Mating System And Genetic Diversity Of Pure-bred Human Ascaris,Pure-bred Pig Ascaris,Hybrized Ascaris

Ascaris lumbricoides and Ascaris suum belong to Ascaridae,Ascaridida,are the major pathogens that parasitize intestine of human and pig,respectively.Ascaris infection can cause serious human health and great economic losses to the pig industry in China and the worldwide.A.lumbricoides and A.suum have similar transmission cycles and morphologies.Cross-transmission of certain haplotypes and hybrids have been observed.The hybrids identification and genetic diversity have been hot topics for researchers.However,previous studies used single molecular markers,such as nuclear genes,mitochondrial DNA or microsatellite markers.In the current study,multiple molecular markers(nuclear gene ITS1,microsatellite DNA and mitochondrial COI and ND1)were applied to investigate hybrids identification,mating system and genetic diversity of Ascaris from human or pig of sympatric populations in China.The results were as follows:1.We select eight polymorphic microsatellite loci to identify the 93 sympatric Ascaris worms from humans(n=43)or pigs(n=45),the results showed that 6 worms were identified as hybrid,5 were obtained from pig bodies with only one from human body.When the nuclear gene ITS1 was used for identification,2 worms were identified as hybrid,and all of them were derived from pig bodies.No cross infection was detected in both methods.2.Five microsatellite loci were used for the study of multiple paternities of the eggs from five female pure-bred human Ascaris.Results showed the primers we used were high polymorphism.Allele counting and GERUD software indicated that each family had at least two fathers,and the relative contribution rate of each sire was different.The microsatellite markers were used to analyze the paternity of the eggs from four female pure-bred pig Ascaris,and the results showed that there was only one sire in each family.When we studied the mating system for hybrized Ascaris,two methods of paternity analysis showed that each of the four families had more than one sire,and the contribution rate of every sire was different.3.The genetic diversity of pure-bred human Ascaris,pure-bred pig Ascaris andhybrized Ascaris based on 8 microsatellite loci showed that a total of 154 alleles were detected.A total of 130 alleles were detected in pure-bred human Ascaris,with an average of 16.25 per locus.A total of 51 alleles were detected in pure-bred pig Ascaris,with an average of 6.375 per locus.A total of 42 alleles were detected in hybrized Ascaris,with an average of 5.25 per locus.In addition,pure-bred human Ascaris,pure-bred human Ascaris and hybrized Ascaris had their own special alleles at eight loci.In terms of allele frequency of each microsatellite locus,the allele frequency was differfence in different populations.The allele frequency distribution of each allele was uneven,and there were one or more advantage alleles at each locus.Analysis of genetic diversity indicated that there was higher genetic diversity in these Ascaris populations,the genetic diversity of pure-bred pig Ascaris was lower.The AMOVA showed 11.57% genetic variation between population and 88.43% within individuals.It showed that the genetic variation mainly occurs between individuals in the population,and genetic differentiation was moderate among these Ascaris populations.The value of Nm ranged from 2.5383 to 7.4230,it indicated that there were different levels of gene exchange between the three populations.4.We found 8 haplotypes in Ascaris from humans and pigs based on mitochondrial COI gene molecular markers.There were 8 haplotypes in the Ascaris from humans,2 haplotypes in the Ascaris from pigs.The haplotype diversity and nucleotide diversity in Ascaris from humans was higher than Ascaris from pigs.Phylogenetic analysis showed that there were three main clusters(A,B and C)for the Ascaris populations all over the world,the eight haplotypes were mainly concentrated in the cluster B.Ascaris from different host were distributed in three clusters except that the cluster C mainly includes Ascaris from pigs.The network revealed that there were three haplogroups,haplogroup A included A1 and A2 subgroups.We found the Ascaris from Africa were mainly distributed in haplogroup A,the haplogroup B mainly contains the Ascaris from Asia,the Ascaris from Europe were mainly distributed in haplogroup C.The Ascaris from South America and North America were distribution in haplogroup A and B,while not found in the haplogroup C.It indicated that Ascaris populations from different geographical location had some isolation differences.We found 15 haplotypes in these populations based onmitochondrial ND1 gene molecular markers.There were 8 haplotypes in the Ascaris from humans,and 9 haplotypes in the Ascaris from pigs.There was no obvious isolation from geographical location and host source based on network.