The Japanese eel(Anguilla japonica)is a commercially important fi sh species in East Asia and its recruitment has been rapidly declining since 1990s.Clarifying the genetic population structure of A.japonica is the bas...The Japanese eel(Anguilla japonica)is a commercially important fi sh species in East Asia and its recruitment has been rapidly declining since 1990s.Clarifying the genetic population structure of A.japonica is the basis of multinational cooperation on its management and protection,due to its large distribution range.Gene-associated markers have been proved powerful in delineating fi ne-scale population genetic structure and spatially varying selection.In the present study,we developed 24 polymorphic gene-associated microsatellite markers including 18 loci associated with the genes under selection in the two North Atlantic eel species(Anguilla anguilla and Anguilla rostrata)and 6 loci based on transcript sequences.A total of 13 geographic populations were sampled across its distribution range,including 11 samples from China(9 from China’s mainland and 2 from Taiwan region),and 2 samples from Japan.A total of 416 individuals(mostly glass eels)were collected and genotyped at the 24 microsatellites.All measures of diff erentiation were accordant with a panmictic scenario(F ST=-0.001)in A.japonica.No footprints of spatially varying selection were found,indicating that the selection pattern in A.japonica might be diff erent from that in the two North Atlantic eel species.We suggest that A.japonica should be managed as a single unit and management and conservation eff orts must be coordinated at the international level,as overexploitation in any region will decrease its recruitment across the whole distributional range.展开更多
[ Objective] To understand the toxicity and sterilization effects of the tetrakis hydroxmethyl phosphonium sulfate （THPS） as a novel quatemary phosphonium biocide. [ Method] Under hydrostatic conditions, the acute t...[ Objective] To understand the toxicity and sterilization effects of the tetrakis hydroxmethyl phosphonium sulfate （THPS） as a novel quatemary phosphonium biocide. [ Method] Under hydrostatic conditions, the acute toxicity and bactericidal property of THPS on the Fiexibacter coiumnaris （ F. columnaris） were observed in Japanese eel. The semi-lethal concentration （LCso）, safe concentration （Sc）, minimum inhibitory concentration （MIC）, minimum bactericidal concentration （MBC） and the sterilization rate of THPS were calculated, respectively. [ Result ] The LCso of THPS at 24, 48 and 96 h were 11.9, 9.9 and 9.1 mg/L, respectively. The Sc of THPS at 24 h was 2.1 mg/L; the MIC and MBC of THPS to the F. columnaris were 0.36 and 0.72 mg/L; and the sterilization rate was 100% at a concentration of 0.7 mg/L at 12 h. The sterilization rate of THPS had no great change with pH values varying from 5.5 to 9.5. [ Condusion] The THPS is a novel, safe and effective biocide for prevention and treatment of bacterial diseases of Japanese eel.展开更多
The Yangtze River and its branches are important habitats for the Japanese Eel(Anguilla japonica),however,there are few data on gonadal development and silvering indices of eels during the downstream spawning migratio...The Yangtze River and its branches are important habitats for the Japanese Eel(Anguilla japonica),however,there are few data on gonadal development and silvering indices of eels during the downstream spawning migration.This study investigates gonadal development in 121 Japanese eels caught downstream from the Jingjiang Reach of the Yangtze River in October 2012.We found that in females the ovaries of most of the out-migrating population developed earlier than the testes in males,that is,the ovaries reached stage 3(F3)or early stage 4(eF4),while the testes were at stage 2(M2)or stage 3(M3).Gonadal development in eels collected in 2012 was earlier than that of samples caught from the same region in 2007e2008 and from the Pearl River Estuary in 1972e1973.The average age,body size and gonadal-somatic index of females were significantly greater than those in males.For both females and males,there were no significant differences between the two stages of gonadal development in any of the morphological indices,which indicates that gonadal development of the Japanese Eel is independent of body size.These results help us to understand the spawning population of Japanese Eels in the Yangtze River.展开更多
基金Supported by the National Natural Science Foundation of China(NSFC)(No.41676137)the Creative Team Project of the Laboratory for Marine Ecology and Environmental Science,Qingdao National Laboratory for Marine Science and Technology(No.LMEES-CTSP-2018-1)。
文摘The Japanese eel(Anguilla japonica)is a commercially important fi sh species in East Asia and its recruitment has been rapidly declining since 1990s.Clarifying the genetic population structure of A.japonica is the basis of multinational cooperation on its management and protection,due to its large distribution range.Gene-associated markers have been proved powerful in delineating fi ne-scale population genetic structure and spatially varying selection.In the present study,we developed 24 polymorphic gene-associated microsatellite markers including 18 loci associated with the genes under selection in the two North Atlantic eel species(Anguilla anguilla and Anguilla rostrata)and 6 loci based on transcript sequences.A total of 13 geographic populations were sampled across its distribution range,including 11 samples from China(9 from China’s mainland and 2 from Taiwan region),and 2 samples from Japan.A total of 416 individuals(mostly glass eels)were collected and genotyped at the 24 microsatellites.All measures of diff erentiation were accordant with a panmictic scenario(F ST=-0.001)in A.japonica.No footprints of spatially varying selection were found,indicating that the selection pattern in A.japonica might be diff erent from that in the two North Atlantic eel species.We suggest that A.japonica should be managed as a single unit and management and conservation eff orts must be coordinated at the international level,as overexploitation in any region will decrease its recruitment across the whole distributional range.
基金supported by the Public Welfare Specialized Research Fund,Ministry of Agriculture ( 200803013)the Director Fund of Pearl River Fisheries Research Institute( 2007-G-6)
文摘[ Objective] To understand the toxicity and sterilization effects of the tetrakis hydroxmethyl phosphonium sulfate （THPS） as a novel quatemary phosphonium biocide. [ Method] Under hydrostatic conditions, the acute toxicity and bactericidal property of THPS on the Fiexibacter coiumnaris （ F. columnaris） were observed in Japanese eel. The semi-lethal concentration （LCso）, safe concentration （Sc）, minimum inhibitory concentration （MIC）, minimum bactericidal concentration （MBC） and the sterilization rate of THPS were calculated, respectively. [ Result ] The LCso of THPS at 24, 48 and 96 h were 11.9, 9.9 and 9.1 mg/L, respectively. The Sc of THPS at 24 h was 2.1 mg/L; the MIC and MBC of THPS to the F. columnaris were 0.36 and 0.72 mg/L; and the sterilization rate was 100% at a concentration of 0.7 mg/L at 12 h. The sterilization rate of THPS had no great change with pH values varying from 5.5 to 9.5. [ Condusion] The THPS is a novel, safe and effective biocide for prevention and treatment of bacterial diseases of Japanese eel.
基金This study was supported by the National Natural Science Foundation of China(No.31201995)the Shanghai Municipal Agricultural Commission(No.20132-2)+1 种基金the Shanghai Municipal Science and Technology Commission of Chongming(No.13231203504)the Open Foundation of Engineering Research Centre of Modern Industrial Technology for Eels,Ministry of Education,China(No.RE201501).
文摘The Yangtze River and its branches are important habitats for the Japanese Eel(Anguilla japonica),however,there are few data on gonadal development and silvering indices of eels during the downstream spawning migration.This study investigates gonadal development in 121 Japanese eels caught downstream from the Jingjiang Reach of the Yangtze River in October 2012.We found that in females the ovaries of most of the out-migrating population developed earlier than the testes in males,that is,the ovaries reached stage 3(F3)or early stage 4(eF4),while the testes were at stage 2(M2)or stage 3(M3).Gonadal development in eels collected in 2012 was earlier than that of samples caught from the same region in 2007e2008 and from the Pearl River Estuary in 1972e1973.The average age,body size and gonadal-somatic index of females were significantly greater than those in males.For both females and males,there were no significant differences between the two stages of gonadal development in any of the morphological indices,which indicates that gonadal development of the Japanese Eel is independent of body size.These results help us to understand the spawning population of Japanese Eels in the Yangtze River.
