Myxozoans are common microscopic endoparasites in fish,and some are highly pathogenic to their wild and farmed fish hosts.In the present study,myxosporeans infection in the kidney of silver carp Hypophthalmichthys mol...Myxozoans are common microscopic endoparasites in fish,and some are highly pathogenic to their wild and farmed fish hosts.In the present study,myxosporeans infection in the kidney of silver carp Hypophthalmichthys molitrix(Valenciennes,1844)from Lake Taihu,was investigated,and two dominate species,Myxobolus lieni(Nie&Li,1973)and M.varius(Achmerov,1960),with infection prevalence 60.2%and 35.2%,respectively,were well characterized based on morphological,histopathological and DNA sequence data.M.lieni formed small roundish plasmodia in the epithelial cells of renal tubules.The mature myxospores appeared suborbicular,slightly flat in frontal view and fusiform shaped in sutural view.Dispersed myxospores of M.varius were found in the renal interstitium without forming plasmodia structures and enclosed within melano-macrophage centers.The spore appeared elliptical in frontal view,with wider anterior than posterior and shuttle shaped in sutural view.Interestingly,the occurrence of myxozoans in the kidney detected with SSU rDNA PCR and clone sequencing,revealed co-infection of five Myxobolus species.BLASTn search indicated SSU r DNA gene sequences obtained here were not identical to any sequence available in GenBank.Phylogenetic analyses showed that the five Myxobolus species detected here were clustered together,forming a separate clade of cyprinid-infecting myxozoans.展开更多
In this report, genetic variation and phylogeny of B. acheilognathi were analyzed based on 96 samples collected from 20 fish host species in 29 different localities by using the rDNA internal transcribed spacer （ITS...In this report, genetic variation and phylogeny of B. acheilognathi were analyzed based on 96 samples collected from 20 fish host species in 29 different localities by using the rDNA internal transcribed spacer （ITS） sequences. The ITS1 and ITS2 sequences of B. acheilognathi varied among 561-639 bp and 559-648 bp, and ten simple sequence repeat loci （microsatellites） were detected in the ITS regions, which contributed to significant sequence length variation. Phylogenetic analyses revealed 4 genetic clades （A, B, C, D） in samples with significantly different fish host spectra and geographic distribution. Clade A possessed a wide host range and geographic distribution, including all the samples ofB. acheilognathi determined in previous report. Clades B, C, and D only infected the small cyprinid fishes Opsariichthys bidens and Zacco platypus, and were limited to different locality. Interesting, Clades A and D were detected coexisting in same water body, and even in same fish host O. bidens in Danjiangkou Reservoir. The relatively higher genetic divergence and wide geographic distribution orB. acheilognathi parasitic in O. bidens indicated that O. bidens is likely to be the primary host. Sympatric occurrence of the two genetically distinct clades suggests the possibility of allopatric speciation and second encounter events.展开更多
基金supported the earmarked fund for China Agriculture Research System of MOF and MARA(CARS-45)Natural Sciences Foundation of China(32073019)。
文摘Myxozoans are common microscopic endoparasites in fish,and some are highly pathogenic to their wild and farmed fish hosts.In the present study,myxosporeans infection in the kidney of silver carp Hypophthalmichthys molitrix(Valenciennes,1844)from Lake Taihu,was investigated,and two dominate species,Myxobolus lieni(Nie&Li,1973)and M.varius(Achmerov,1960),with infection prevalence 60.2%and 35.2%,respectively,were well characterized based on morphological,histopathological and DNA sequence data.M.lieni formed small roundish plasmodia in the epithelial cells of renal tubules.The mature myxospores appeared suborbicular,slightly flat in frontal view and fusiform shaped in sutural view.Dispersed myxospores of M.varius were found in the renal interstitium without forming plasmodia structures and enclosed within melano-macrophage centers.The spore appeared elliptical in frontal view,with wider anterior than posterior and shuttle shaped in sutural view.Interestingly,the occurrence of myxozoans in the kidney detected with SSU rDNA PCR and clone sequencing,revealed co-infection of five Myxobolus species.BLASTn search indicated SSU r DNA gene sequences obtained here were not identical to any sequence available in GenBank.Phylogenetic analyses showed that the five Myxobolus species detected here were clustered together,forming a separate clade of cyprinid-infecting myxozoans.
基金supported by the National Natural Sciences Foundation of China(31302222)the Freshwater Fisheries Research Center,CAFS Grant(2013JBFM10)the earmarked fund for China Agriculture Research System(CARS-46)
文摘In this report, genetic variation and phylogeny of B. acheilognathi were analyzed based on 96 samples collected from 20 fish host species in 29 different localities by using the rDNA internal transcribed spacer （ITS） sequences. The ITS1 and ITS2 sequences of B. acheilognathi varied among 561-639 bp and 559-648 bp, and ten simple sequence repeat loci （microsatellites） were detected in the ITS regions, which contributed to significant sequence length variation. Phylogenetic analyses revealed 4 genetic clades （A, B, C, D） in samples with significantly different fish host spectra and geographic distribution. Clade A possessed a wide host range and geographic distribution, including all the samples ofB. acheilognathi determined in previous report. Clades B, C, and D only infected the small cyprinid fishes Opsariichthys bidens and Zacco platypus, and were limited to different locality. Interesting, Clades A and D were detected coexisting in same water body, and even in same fish host O. bidens in Danjiangkou Reservoir. The relatively higher genetic divergence and wide geographic distribution orB. acheilognathi parasitic in O. bidens indicated that O. bidens is likely to be the primary host. Sympatric occurrence of the two genetically distinct clades suggests the possibility of allopatric speciation and second encounter events.
