The appearance of abnormal growths on the planarian, Dugesia dorotocephala, in response to cadmium with and without pre-exposure to L-buthionine-R, S-sulfoximine (BSO) and concurrent exposure to the polychlorinated bi...The appearance of abnormal growths on the planarian, Dugesia dorotocephala, in response to cadmium with and without pre-exposure to L-buthionine-R, S-sulfoximine (BSO) and concurrent exposure to the polychlorinated biphenyls (PCBs) Aroclor 1254, PCB 28, PCB 110 or PCB 126 is described. Pigmented rose thorn (PRT) lesions were non-invasive and appeared in response to PCBs. Post-head (PH) lesions developed in up to 100% of the animals within 6-20 days post-dosing, progressed rather rapidly and were highly invasive. Round tail tip (RTT) lesions appeared in lower frequencies within 10-30 days, but progressed extremely rapidly resulting in tail loss within 48 h. We have referred to these types of lesions as 'tumors', but they are not necessarily characteristic of vertebrate neoplasms.PCBs interacted with cadmium in a complex way, in some cases increasing total lesions and decreasing time-to-lesion and in other cases having the opposite effects. A three-factor (PCB, PCB dose, Cd dose) nested analysis of variance model was used to determine lesion rates in order to compare PCB potencies as potentiators or antagonists. The Aroclor mixture was always the least potent co-toxicant but appeared to be the most potent antagonist; the coplanar PCB 126 was the most potent co-toxicant. The complex response surfaces and the lack of stoichiometry in dose-response relationships indicate that multiple mechanisms are responsible for PH and RTT lesions in planarians. These results emphasize the complexity of PCB toxicities and suggest further studies to validate the planarian model as a screen for combinations or environmental mixtures which may have altered biological potency in other species.展开更多
Freshwater planaria has tremendous capacity to reform the missing part of the body and therefore is considered as one of the most important model organism for regeneration study. At present, Schmidtea mediterranea and...Freshwater planaria has tremendous capacity to reform the missing part of the body and therefore is considered as one of the most important model organism for regeneration study. At present, Schmidtea mediterranea and Dugesia japonica are the two major species utilized for laboratory manipulations. Dugesia japonica flatworms are widely distributed in the Far East including Cherry Valley region in the north-west area of Beijing, China. We reported here the establishment of an asexual Dugesiajaponica strain Pek-1, as a suitable system for regeneration study. Using morphological, karyotypical as well as phylogenetic analyses, we confirmed that these flatworms indeed belonged to Dugesia japonica. We went on to show that the commonly used in situ probes and immunohistochemistry reagents and protocols were applicable to the Pek-1 strain. Using this strain, we carried out small scale analysis on EST, RNAi and gene expression. We identified 193 unique EST sequences and 65 of them had not been reported in planarian. By RNAi analysis, we showed that 48 genes, when down-regulated individually, had no effect on regeneration. Furthermore, we identified 3 groups of tissue specific expressing genes that were useful for cell lineage analysis. We concluded that the Dugesiajaponica Pek-1 strain could be another suitable animal model to regeneration research.展开更多
Certain freshwater planarians reproduce asexually as well as sexually,and their chromosomal ploidies include polyploidy,aneuploidy and mixoploidy.Previously,we successfully performed an experiment in which a clonal po...Certain freshwater planarians reproduce asexually as well as sexually,and their chromosomal ploidies include polyploidy,aneuploidy and mixoploidy.Previously,we successfully performed an experiment in which a clonal population produced by asexual reproduction of the Dugesia ryukyuensis(OH strain)switched to the sexual mode of reproduction.Worms of this strain are triploid with a pericentric inversion on Chromosome 4.The worms were switched to sexual reproduction after being fed with sexually mature Bdellocephala brunnea,which is a sexually reproducing species.The resulting sexualized OH strain produced cocoons filled with several eggs.Two putative factors,Mendelian factor(s)and chromosomal control(s),have been proposed as determining the reproductive mode.The present study demonstrated that inbreeding of the resultant sexualized worms produced the following four types of offspring through sexual reproduction:diploid asexual worms,triploid asexual worms,diploid sexual worms and triploid sexual worms.The chromosomal mutation on Chromosome 4 was inherited by these offspring independent of their reproductive mode.These results provide two important pieces of information:(i)the putative genetic factor was not necessarily inherited in a Mendelian fashion;and(ii)the reproductive mode is not regulated by chromosomal changes such as polyploidy or chromosomal mutations.This suggests that asexuality in D.ryukyuensis is regulated by an unknown factor(s)other than a Mendelian factor or a chromosomal control.展开更多
The freshwater planarian Dugesia japonica has become a model organism in regeneration biology and toxicology due to its powerful regeneration capability and highly chemical sensitivity.Nonetheless,little is known abou...The freshwater planarian Dugesia japonica has become a model organism in regeneration biology and toxicology due to its powerful regeneration capability and highly chemical sensitivity.Nonetheless,little is known about its evolutionary history and demographics.Taihang Mountains is the natural boundary between the Loess Plateau and the North China Plain,and is considered as one of the important priority areas for biodiversity conservation in China.In order to figure out the genetic diversity,population structure and demographic history of D.japonica in Taihang Mountains,a study based on the mitochondrial COI from 116 individuals sampled across 20 populations has been conducted.The results showed that the 116 COI sequences yielded 32 haplotypes,including 8 shared haplotypes and 24 private ones.The overall haplotype diversity(Hd)and nucleotide diversity(π)were 0.920 and 0.083,respectively.Even though the AMOVA results suggested that the genetic variation among populations was significant(FST=0.480,P<0.01),the phylogeny and haplotype network analysis based on 32 haplotypes revealed no obvious phylogeographic pattern.Furthermore,the significantly positive values of neutrality test(Tajima’s D=2.596,P<0.05;Fu’s Fs=2.769,P<0.01)together with the multimodal arrangement of mismatch distribution indicated that D.japonica in Taihang Mountains would have been undergoing population decline.We hope these findings will arouse conservation and management strategy regarding freshwater planarians and contribute to the biodiversity in the long run.展开更多
文摘The appearance of abnormal growths on the planarian, Dugesia dorotocephala, in response to cadmium with and without pre-exposure to L-buthionine-R, S-sulfoximine (BSO) and concurrent exposure to the polychlorinated biphenyls (PCBs) Aroclor 1254, PCB 28, PCB 110 or PCB 126 is described. Pigmented rose thorn (PRT) lesions were non-invasive and appeared in response to PCBs. Post-head (PH) lesions developed in up to 100% of the animals within 6-20 days post-dosing, progressed rather rapidly and were highly invasive. Round tail tip (RTT) lesions appeared in lower frequencies within 10-30 days, but progressed extremely rapidly resulting in tail loss within 48 h. We have referred to these types of lesions as 'tumors', but they are not necessarily characteristic of vertebrate neoplasms.PCBs interacted with cadmium in a complex way, in some cases increasing total lesions and decreasing time-to-lesion and in other cases having the opposite effects. A three-factor (PCB, PCB dose, Cd dose) nested analysis of variance model was used to determine lesion rates in order to compare PCB potencies as potentiators or antagonists. The Aroclor mixture was always the least potent co-toxicant but appeared to be the most potent antagonist; the coplanar PCB 126 was the most potent co-toxicant. The complex response surfaces and the lack of stoichiometry in dose-response relationships indicate that multiple mechanisms are responsible for PH and RTT lesions in planarians. These results emphasize the complexity of PCB toxicities and suggest further studies to validate the planarian model as a screen for combinations or environmental mixtures which may have altered biological potency in other species.
基金supported by grant from the National Natural Science Foundation of China to W.W. (No. 30670225)
文摘Freshwater planaria has tremendous capacity to reform the missing part of the body and therefore is considered as one of the most important model organism for regeneration study. At present, Schmidtea mediterranea and Dugesia japonica are the two major species utilized for laboratory manipulations. Dugesia japonica flatworms are widely distributed in the Far East including Cherry Valley region in the north-west area of Beijing, China. We reported here the establishment of an asexual Dugesiajaponica strain Pek-1, as a suitable system for regeneration study. Using morphological, karyotypical as well as phylogenetic analyses, we confirmed that these flatworms indeed belonged to Dugesia japonica. We went on to show that the commonly used in situ probes and immunohistochemistry reagents and protocols were applicable to the Pek-1 strain. Using this strain, we carried out small scale analysis on EST, RNAi and gene expression. We identified 193 unique EST sequences and 65 of them had not been reported in planarian. By RNAi analysis, we showed that 48 genes, when down-regulated individually, had no effect on regeneration. Furthermore, we identified 3 groups of tissue specific expressing genes that were useful for cell lineage analysis. We concluded that the Dugesiajaponica Pek-1 strain could be another suitable animal model to regeneration research.
基金supported in part by a Grant-in-Aid for Scientific Research(Nos.100082 and 16086209)from the Ministry of ScienceCulture,Sports and Education,Japan(MH and MM)and from PRESTO,Japan Science and Technology Corporation(KK).
文摘Certain freshwater planarians reproduce asexually as well as sexually,and their chromosomal ploidies include polyploidy,aneuploidy and mixoploidy.Previously,we successfully performed an experiment in which a clonal population produced by asexual reproduction of the Dugesia ryukyuensis(OH strain)switched to the sexual mode of reproduction.Worms of this strain are triploid with a pericentric inversion on Chromosome 4.The worms were switched to sexual reproduction after being fed with sexually mature Bdellocephala brunnea,which is a sexually reproducing species.The resulting sexualized OH strain produced cocoons filled with several eggs.Two putative factors,Mendelian factor(s)and chromosomal control(s),have been proposed as determining the reproductive mode.The present study demonstrated that inbreeding of the resultant sexualized worms produced the following four types of offspring through sexual reproduction:diploid asexual worms,triploid asexual worms,diploid sexual worms and triploid sexual worms.The chromosomal mutation on Chromosome 4 was inherited by these offspring independent of their reproductive mode.These results provide two important pieces of information:(i)the putative genetic factor was not necessarily inherited in a Mendelian fashion;and(ii)the reproductive mode is not regulated by chromosomal changes such as polyploidy or chromosomal mutations.This suggests that asexuality in D.ryukyuensis is regulated by an unknown factor(s)other than a Mendelian factor or a chromosomal control.
基金supported by the National Natural Science Foundation of China(31702010)Major Public Welfare Project of Henan Province(201300311700)Puyang Field Scientific Observation and Research Station for Yellow River Wetland Ecosystem,Henan Province。
文摘The freshwater planarian Dugesia japonica has become a model organism in regeneration biology and toxicology due to its powerful regeneration capability and highly chemical sensitivity.Nonetheless,little is known about its evolutionary history and demographics.Taihang Mountains is the natural boundary between the Loess Plateau and the North China Plain,and is considered as one of the important priority areas for biodiversity conservation in China.In order to figure out the genetic diversity,population structure and demographic history of D.japonica in Taihang Mountains,a study based on the mitochondrial COI from 116 individuals sampled across 20 populations has been conducted.The results showed that the 116 COI sequences yielded 32 haplotypes,including 8 shared haplotypes and 24 private ones.The overall haplotype diversity(Hd)and nucleotide diversity(π)were 0.920 and 0.083,respectively.Even though the AMOVA results suggested that the genetic variation among populations was significant(FST=0.480,P<0.01),the phylogeny and haplotype network analysis based on 32 haplotypes revealed no obvious phylogeographic pattern.Furthermore,the significantly positive values of neutrality test(Tajima’s D=2.596,P<0.05;Fu’s Fs=2.769,P<0.01)together with the multimodal arrangement of mismatch distribution indicated that D.japonica in Taihang Mountains would have been undergoing population decline.We hope these findings will arouse conservation and management strategy regarding freshwater planarians and contribute to the biodiversity in the long run.
