Apart from the liver disruption, embryotoxicity and genotoxicity, microcystin (MC)-LR also could cause neurotoxicity. Nematode Caenorhabditis elegans was explored as a model to study the neurotoxicity. In the present study, we provided evidence to indicate the neurotoxicity on chemotaxis to NaCl and diacetyl, and thermotaxis from MC-LR exposure to C. elegans. As a result, higher concentrations of MC-LR caused significantly severe defects of chemotaxis to NaCl and diacetyl, and thermotaxis. The neurotoxicity on chemotaxis to NaCl and diacetyl, and thermotaxis from MC-LR exposure might be largely mediated by the damage on the corresponding sensory neurons (ASE, AWA, and AFD) and interneuron AIY. The expression levels of che-1 and odr-7 were significantly decreased (P < 0.01) in animals exposed to MC-LR at concentrations lower than 10 μg/L, whereas the expression levels of ttx-1 and ttx-3 could be significantly (P < 0.01) lowered in animals even exposed to 1 μg/L of MC-LR. Moreover, both the chemotaxis to NaCl and diacetyl and the thermotaxis were more significantly reduced in MC-LR exposed mutants of che-1(p674), odr-7(ky4), ttx-1(p767), and ttx-3(ks5) than those in exposed wild-type N2 animals at the same concentrations.
LI YunhuiYE HuayueDU MinZHANG YanfenYE BopingPU YuepuWANG Dayong
Toxicity identification evaluation (TIE) can be used to determine the specific toxicant(s) in industrial effluents.In the current study,the authors have attempted to combine the advantages of the model organism,Caenorhabditis elegans,with the virtues of the TIE technique,to evaluate and identify the toxicity on aging from a paper recycling mill effluent.The results indicate that only the toxicities from mixed cellulose (MC) filtration and EDTA treatment are similar to the baseline aging toxicity,suggesting that the suspect toxicants inducing aging toxicity may largely be the heavy metal substances in this industrial effluent.Examination of the accumulation of intestinal autofluorescence in adult animals further confirms that the short lifespans are actually due to accelerated aging.In addition,exposure to fractions of EDTA manipulations cannot result in severe defects of reproduction and locomotion behaviors in C.elegans.Moreover,high levels of Ca,Al,and Fe in the effluent may account for the severe toxicity on aging of exposed nematodes,by TIE assay.The study here provides a new method for evaluating environmental risk and identifying toxicant(s) from the industrial effluent using C.elegans.
We used toxicity identification evaluation (TIE) method to confirm the combinational effects of identified toxic metals in a paper recycling mill effluent in inducing the decreased lifespan in nematode Caenorhabditis elegans.Exposure to Ca + Al caused more severely decreased lifespan than that exposed to Ca,or Al;and exposure to Ca + Fe induced more severely decreased lifespan than that exposed to Ca,or Fe.Exposure to Ca+Al+Fe caused more severely decreased lifespan than that exposed to Ca,or Ca+Fe.Moreover,the baseline toxicity on lifespan was doubled by doubling the concentration of combined metals (Ca+Al+Fe) in spiking test in original effluent (oe),and lifespan defects in oe+Ca+Al+Fe exposed nematodes were more severe than that in Ca+Al+Fe exposed nematode.Therefore,Ca+Al+Fe exposure may largely explain the formation of decreased lifespan induced by the examined industrial effluent.Furthermore,the observed reduction of lifespan induced by the combination of high level of Ca with other metals may be at least partially independent of the insulin-like pathway.
Dayong Wang,Yang Wang,Lulu Shen Key Laboratory of Developmental Genes and Human Disease in Ministry of Education,Department of Genetics and Developmental Biology,Southeast University Medical School,Nanjing 210009,China.
