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    • 专利摘要:
    The invention is related to the field of contaminant ecotoxicity assessment, and in particular to a method for predicting toxicity of arsenic to wheat root elongation. Complexing stability constants of AsO43', HAsO42', HzAsO4', H3AsO4, H2PO4', and 8042' for wheat root ligand are estimated based on BLM so as to establish the BLM adapted to predict toxicity of As(V) to wheat. After determining concentrations of AsO43', HAsO42', HzAsO4', H3AsO4, H2PO4', and 8042' in a soil for growing wheat, values thereof are substituted into the established BLM so as to predict toxicity of As(V) to wheat root elongation. So, complexing stability constants of the various As(V) forms or species and of the coexisting anions for the wheat root ligand are estimated, and As(V)-BLM predictive of the As(V) toxicity to wheat root elongation is established, which may provide scientific basis for verification of the BLM for predicting the toxicity of As(V) in soil, ecological risk assessment for As(V) contaminated soil, and formulation of environmental quality standards for As(V) contaminated soil.
    公开号:NL2028028A
    申请号:NL2028028
    申请日:2021-04-21
    公开日:2021-07-20
    发明作者:Song Ningning；Li Shaojing
    申请人:Univ Qingdao Agricultural；
    IPC主号:
    专利说明:

    METHOD FOR PREDICTING TOXICITY OF ARSENIC TO WHEAT ROOT
    ELONGATION BY USING BIOTIC LIGAND MODEL Technical Field The present invention is related to the field of contaminant ecotoxicity assessment, and in particular to a method for predicting toxicity of arsenic to wheat root elongation. Background Arsenic (As(V)), as a metalloid element, may cause animal poisoning and even cancers, and is one of the toxic elements that cause surface soil pollution. Arsenic is present in nature as organic and inorganic arsenic, and many arsenic compounds are toxic.
    Inrecentyears, a Biotic Ligand Model (BLM) has been developed for evaluating toxicity of heavy metals contained in water bodies. Currently, however, the BLM is mainly applied to the prediction of the toxicity of heavy metals in water, and the BLM adapted to the prediction of the toxicity of heavy metals in soil is rarely reported. Especially, predictive model for studying effects of anions and pH value on the arsenic toxicity has yet not been reported.
    Summary In view of the above problems, an objective of the invention is to provide a method for predicting toxicity of arsenic to wheat root elongation, which makes possible an accurate prediction of the toxicity of arsenic to wheat root elongation.
    Accordingly, an objective of the invention is realized by a method for predicting toxicity of arsenic to wheat root elongation, comprising steps of: a. determining concentrations of AsOa*, HAsO: , H2AsO:, H3AsOs, H:POr, and SO:” in a soil for growing wheat, with the concentrations being expressed in the same unit; and b. substituting the determined values of the AsO:*, HASO”, H2AsO:, H3AsO4, HPO, and SO4* concentrations into Formula (I) to calculate relative root elongation;
    dE aM Ky EO BJT AIOE Re) US Epon HO Kappan ROTC Ego WOE JS Kp rn FASO EN pron SPO |F Kine fos Formula (I) where, RE represents the relative root elongation, logK1s048:=3.48-3.92, logKH4s0481=3.96-4.20, logKi24s04s,=4.75-4.79, logK34s0481=6. 14-6.86, logKmrosg=1.97-2.21, logKsom=l1.64-2.08, fit =0.28-0.32, p=1.67-1.79; and, {ASO}, {HAsO#}, {H2AsOr}, {H3AsOs}, {H;POr}, and {SO4*} represent the determined vales of the AsO4”, HAsO:%, H2AsO:, H3AsQs, H:POr, and SO: concentrations, respectively.
    In a preferred embodiment, the step (b) further comprises: substituting the determined values of the AsO:*, HAsO:%, HAsO", H3AsO4, H:PO:, and SOs concentrations, obtained in the step (a), into Formulas (TT) to (V) to calculate EC50 of AsO4%, HAsO:%, H;AsO:, and H3AsO4 on wheat root system, respectively; 371 — EC50{As0;"} = Facts (1+K ppo pL{H2POF 4K 50, 80{S057}) | % {HAs0%™) {Ha AsO7} {H3As04} (13250) Kaon Koso aen TE Kina EEE it 0,0 E2250 Formula (II) 2-7 _ EC50{HAsO;"} = facth (14K, po, BL{B2P07}+Ks0,81{8077}) 50% - {as03 7} {H24s03]} [HyAsO4})”’ GEE Kuasoaer HK aso erk aso ei EK aso ei ASE Formula (IIT) EC50{H,As0;} = Fason(1+Kn, po, BL {H,POTI+Ks0, 51 {S03 7) } % {as03™) [HAso3T] [H2A504}) EN Kita As, 21K ts EE Formula (IV)
    EC50{H;As0,} = Fats (14K, po, BL{H2PO7}+Ks0,81{8077}) } 03 O02 sO CN Kita 1s0, m1 +K ps0, 1p Ki nh 50 51 ats Formula (V) in the formulas (II) to (V), logKaor=3.48-3.92, logKaaso48r=3.96-4.20, logKn2is04:=4.75-4.79, logKn3.150481=6.14-6.86, logKn2p048:=1.97-2.21, logKsoser=1.64-2.08, fix =0.28-0.32, p=1.67-1.79; and, {AsOs"}, {HAsO}, {HoAsO:}, {H3AsO4}, {HPO}, and {SO: } represent the determined vales of the AsO, HASO, H2AsOr, H3AsO,, HPO, and SO,” concentrations, respectively.
    In a preferred embodiment, the wheat variety comprises Jimai 22, Jimai 23, Jimai 44 and Yanmai 1212. The present invention provides a method for predicting toxicity of arsenic(V) to wheat root elongation, which is based on the Biotic Ligand Model (BLM). According to the method, complexing stability constants of AsO4 , HAsO:”, H2AsO:, H3AsO4, HPO, and SO for the wheat root ligand are estimated based on BLM so as to establish the BLM adapted to predict the toxicity of As(V) to wheat.
    After determining the concentrations of AsOa*, HAsOa*, H:AsO:, H3AsO4, H:PO:, and SO4* in a soil for growing wheat, values thereof are substituted into the established BLM so as to predict the toxicity of As(V) to wheat root elongation.
    So, according to the invention, complexing stability constants of the various As(V) forms or species and of the coexisting anions for the wheat root ligand are estimated, and As(V)-BLM predictive of the As(V) toxicity to wheat root elongation is established, which may provide scientific basis for verification of BLM adapted to the prediction of the toxicity of As(V) in soil, ecological risk assessment for As(V) contaminated soil, and formulation of environmental quality standards for As(V) contaminated soil.
    Brief Description of the Drawings FIG. 1 shows distribution of various As(V) forms at different pH levels; FIG. 2 illustrates relationships between EC50 values and ion activities, where A indicates a relationship between EC50{AsO:*} and H POs activity, B indicates a relationship between EC50{AsO4*} and SO. activity, C indicates a relationship between ECS0{HAsO:*} and H,POys activity, D indicates a relationship between EC50{HAs0: } and SO: activity, E indicates a relationship between EC50{H2AsO:} and HoPO- activity, F indicates a relationship between EC50{H:As0:} and SO4* activity, G indicates a relationship between EC50{H3AsO4} and HPO: activity, and H indicates a relationship between EC50{H3As04} and SO4% activity; FIG. 3 shows a dose-response curve for inhibition of wheat root elongation by various As(V) forms, where A indicates a relationship between AsO:% activity and wheat root elongation, B indicates a relationship between HAsO:” activity and wheat root elongation, C indicates a relationship between H:AsO- activity and wheat root elongation, D indicates a relationship between H:AsO: activity and wheat root elongation, and E indicates a relationship between partition coefficient based on the BLM theory and measured wheat root lengths; FIG. 4 illustrates relationships between predicted values of wheat root lengths and measured values thereof, where A indicates a relationship therebetween known from AsO:*-FIAM: B indicates a relationship therebetween known from HAsO4*-FIAM, C indicates a relationship therebetween known from H2AsO:-FIAM, D indicates a relationship therebetween known from H3AsO4-FIAM, and E indicates a relationship therebetween known from BLM; and FIG. 5 illustrates relationships between predicted EC50 values and measured EC50 values, where A indicates a relationship between predicted and measured EC50{AsO:’}, B indicates a relationship between predicted and measured EC50{HAsO,>}, C indicates a relationship between predicted and measured EC50{H:AsO:}, and D indicates a relationship between predicted and measured EC50{H3AsO4}; and where the dashed lines indicate a very good agreement between predicted values and measured values, and the solid lines indicate the predicted values within 2 times the measured values.
    Detailed Description The present invention provides a method for predicting toxicity of arsenic to wheat root elongation, comprising steps of:
    a. determining concentrations of AsO:”, HAsO4*", H2AsO-, H3AsO4, H2PO, and SOs in a soil for growing wheat, with the concentrations being expressed in the same unit; and b. substituting the determined values of the AsO4%, HAsO:%”, H2AsO:, H3AsO4, H:POr, 5 and SO4* concentrations into Formula (I) to calculate relative root elongation; In { Kost fs $4 ose ADT} Koot i, As PO} Konan 8 f AH Ou ¥ UH EINK on SG TE OST Ko BAO TYR FLAS pn VED 1 Ey, 6 1 Formula (I) where, RE represents the relative root elongation; logK4sw42r=3.48-3.92, logKr450481=3.96-4.20, logK24s0481=4.75-4.79, logK#3:s0421=6. 14-6.86, log&mzros=l1.97-2.21, logKsossr=l1.64-2.08, fiom =0.28-0.32, p=1.67-1.79; and, {AsO}, {HAsO4#}, {HoAsO:}, {H3AsO4}, {H;PO:}, and {SO4 } represent the determined vales of the AsO:*”, HAsO, H;AsO:r, H3AsO4, H;POr, and SO: concentrations, respectively. According to the method, the concentrations of AsO4*, HAsO:, HAsO", H3AsO,4, HPO, and SO4” in a soil for growing wheat are first determined, with the concentrations being expressed in the same unit. Preferably, the wheat variety comprises Jimai 22, Jimai 23, Jimai 44 and Yanmai 1212. Further, after the concentrations of AsO4*, HAsO:”, H2AsO:, H3AsO4, H:PO, and SO:” are determined, the determined values thereof are substituted into a model as shown in Formula (I) to calculate relative root elongation;
    RE . { Ku sO Tr Ko HAWS be Eea PO a Ea EO} Y SNEL KLLIESe ELLE ELLE De LPT ESE, Formula (I) where, RE represents the relative root elongation; logK4sw42r=3.48-3.92, logKiis0451=3.96-4.20, logKnz.4s048:=4.75-4.79, logK i3.450481=6.14-6.86,
    logKrorosmi=1.97-2.21, logKsoum=1.64-2.08, fio =0.28-032, p=1.67-1.79, preferably, 1ogK 45045:=3.70, logKu1w0sm:=4.08, logKn245048:=4.77, logK 13.150451=06.50, logKr2004.=2.09, logKso4:1=1.86, fi =0.30, f=1.73; and, {AsOs*}, {HAsO}, {H2As047}, {H3AsO4}, {H:PO-r}, and {SO4 } represent the determined vales of the AsO." HAsO:”, HaAsO:, H3AsO4, HPO, and SO,” concentrations, respectively.
    Preferably, after the concentrations of AsO:*, HAsO4>", H2AsO-, H3AsO4, HoPOr, and SO” are determined, the method further comprises: substituting the determined values of the AsO:*, HAsO: %, H2AsO:, HiAsQs, H:PO:, and SO: concentrations into Formulas (TT) to (V) to calculate EC50 of AsO4*, HAsO:”, H2AsO:, and H3AsO: on wheat root system, respectively; EC50{As037} = F&spL(1+K hypo, 81 {HPO 14K 50,80 {S05 }) (1 R280) Kasousu Koso aar ogi Kins asi FE Kit 0,0 S08) | Formula (II) EC50{HAs0%7} = [iss (1+Ku, po, BL: POT} +Ks0,5{S047)) } EN Kinaso i+ K asoy mii Ki aso mr BSE rps, mn AS04) Formula (11) EC50{H,AsO;} = fasti(1+Kn, po, BL {HPO} +Ks0,8.{S03}) ) (12280) Kit 0, m1 +H EE) Formula (IV) EC50{H;As0,} = Fasti(1+Kn, po, pL{H2PO;}+Ks0,51{S037}) (1-123) Kase an aso eee Ks, LK i 150,51 Spa) Formula (V)
    in the formulas (II) to (V), logK1om:=3.48-3.92, logKiis045:=3.96-4.20, logK24504p1=4.75-4.79, coos logK 3.450481 =0.14-6.806, logKs2po481=1.97-2.21, Snr logKsomi=1.64-2.08, =0.28-0.32, p=1.67-1.79; and, {AsO:"}, {HAsO}, {H2AsOr}, {H3AsO4}, {H;POr}, and {SO} represent the determined vales of the AsOs>, HAsO:”, HoAsO:, H3AsOs, HPO, and SO concentrations, respectively. In the case of Jimai 22, for the formulas (I), (II), and (III), logK4s048:=3.70, logKr1s041=4.08, logKm2usour=4.77, 1ogKiz4505.=6.50, logKizropr=2.09, logKsosm=1.86, f sur =0.30, and 8=1.73. The invention will now be described in connection with example embodiments. Apparently, these example embodiments are not all of but only part of the embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments described herein without creative efforts shall fall within the protection scope of the invention, Example 1 By way of culturing of soil simulation solutions, variations in the toxicity of As(V) to wheat root elongation with pH value were studied, and bio-available forms of As(V) which were considered to be toxic to wheat root elongation were also determined. Further, Effects of CI", NO; SO:4%, and H:PO- in differing concentrations on the As(V) toxicity to wheat root elongation were investigated through the single factor test. Complexing stability constants of the various As(V) forms and of the coexisting anions for the wheat root ligand were estimated, and As-BLM predictive of the As(V) toxicity to wheat root elongation was established, which could provide scientific basis for verification of the BLM for predicting the toxicity of As(V) in soil, ecological risk assessment for As contaminated soil, and formulation of environmental quality standards for As contaminated soil. Materials and methods
    1. Experimental materials
    Agents: sodium arsenate, calcium chloride, sodium chloride, sodium sulfate, sodium nitrate, sodium dihydrogen phosphate, sodium hydroxide, and hydrogen chloride (for other agents to be used and amounts thereof, see a non-patent document: Ningning Song, etc., Development of a Multi-Species Biotic Ligand Model Predicting the Toxicity of Trivalemt Chromium to Barley Root Elongation in Solution Culture, PLoS ONE,
    10.137 1journal.pone.0105174, 9, 8, (e105174), (2014). Experimental wheat variety: Jimai 22.
    2. Preparation of solutions To investigate the effects of changes in pH value and in concentrations of H2PO-, SO: , NOs, and Cl’ on the toxicity of As to wheat root elongation. Solutions containing the corresponding ions were prepared for future use. The concentrations of the ions in the corresponding solutions and pH values of solutions are shown in Table 1. Table 1 Chemical compositions of test solutions in each run Group Ion concentration or pH value others SO (mM) 0.5,1,2.5,5,10,15 mM pH 6.0 H>PO*(mM) 0.5,1,2.5,5.10,15 mM 0.2 mM Ca, pH 6.0 NO: (mM) 1,2.5,5,10,30 mM 0.2 mM Ca, pH 6.0 Cl'(mM) 1,2.5,5.10,15,30 mM 0.2 mM Ca, pH 6.0 pH 4.5,5.0,5.5,6.0,6.5,7.0,7.5,8.0 0.2 mM Ca
    3. Wheat root elongation inhibition test Referring to the test method for wheat growth and cultivation in soil, plastic beakers, suitable for growth of wheat seedlings, and healthy and plump wheat seeds were selected. The selected seeds were sterilized using 30 % H20: for 20 min. Thereafter, they were cleaned by flushing with deionized water, and were then placed on an iron dish lined with a sterilized filter paper. Deionized water was then added to the dish such that the seeds were submerged in water. The dish was then placed into an incubator for culturing at 20 °C for 36 h without light irradiation. The seeds were transferred into the plastic beakers after radicle emergence and root growth up to 2 mm, with 7 seeds in each beaker for further culturing (14 h and (24+2) °C per day, 10 h and (18+2) °C per night, and illumination intensity: 25000 Ix). Seed culture liquid exchange was performed once every 2 days. After 5 days, root lengths were measured and relative root elongation (RE, %) of wheat subjected to the solutions having differing concentrations of As was calculated.
    4. Prediction of As forms The forms or species of As were predicted using Visual Minteq3.0 software.
    5. Statistic processing of data Dose-response curves were fitted with the log-logistic equation (Formula TV), ¥0 Jr l+elz-a)b Formula (IV) where, x represents natural logarithm of As(V) dose, yo and b are fitted parameters, a=logio(EC50), and y represents a value of an evaluation index. The curve fitting was conducted through a method as described in a non-patent document: Ningning Song, etc., Development of a Multi-Species Biotic Ligand Model Predicting the Toxicity of Trivalent Chromium to Barley Root Elongation in Solution Culture, PLoS ONE,
    10.137 journal. pone 0105174, 9, 8, (e105174), (2014). The statistical analysis of the data was carried out by the software of Statistic Package for Social Science (SPSS), and the data value of the significant difference should below 0.05 (p<0.05).
    Here, when the data value of the significant difference was below 0.05 (p<0.05), the least significant difference test (LSD) of one-way ANOVA analysis was used for statistics.
    6. Mathematical basis of As(V)-BLM As(V) was present in the solutions having a pH value of 4.5 to 8.0 in the forms of AsO:*, HAsO4%, HoAsO-, and H3AsOs. AsO4* was regarded as the toxic form of As(V) which was most likely to act on the biological ligand. According to the hypothesis of the BLM, when the competing ions including OH’, HPO, SO4*, NOs”, and CT were taken into account, the fraction of all BL binding sites occupied by the AsOa* ions was defined as f (also called partition coefficient), the magnitude of which is independent of biomass and the total number of the ligands. The partition coefficient f could be expressed as a following Equation (1): Koo zr 480 | J _ asa,pr YAY zn 408 Le dai DELE goal ar hal ye Iet a 1+ K 6 501450 i+ Kop: OH (+ Ky po LPO + Ki 50 WOT 1+ Ky NWO, + Kipp ET | Equation (1) When 50 % inhibition occurred, Equation (1) could be represented by a following Equation (2): u fw 5 ] i ‚ . Co EC50450 | “1 f HK (+ Koy OH Jt Ki po HL PO; + Kou SCE + Kaos WO f+ KogriCT ) CT gua EOL Equation (2) where, EC50{AsQ4""} represents the activity of free arsenic ions at 50 % inhibition of {9% wheat root elongation, and = *°* represents the fraction of all wheat root binding sites occupied by the arsenic ions at 50 % inhibition of wheat root elongation. The relative root elongation could be expressed as a following Equation (3): 100 REF =—"—"— {/ { 4 4704BL 1 + | fee |
    LT CBL J Equation (3) From Equation (1) above, Equation (3) could be transformed into a following Equation (4): it Kor so} | Ff oe Ue Ko. 450 x I Kous OH - jt K H,POBL LP a Jt K Say BL 507 f+ K NO;BL WO. | +k CIBL Ct - Vl Equation (4)
    Equation (4) was the mathematical basis of As-BLM. Root Mean Square error (RMSE) acquired by fitting using DPS 9.0 software was used as a criterion for determining optimal parameters, RAS © = J (B roasrred - R rogicted ) 4 1 Equation (5) where, N is the number of data to be processed, Rmeasured is a measured value of relative root elongation, and Rpredictea is a predicated value of relative root elongation. Results and analysis
    1. Distribution of various forms of As(V) at different pH levels Distribution of various forms of As(V) at pH levels of 4.5 to 8.0 is as shown in FIG. 1. With the pH was increased, the AsO4* and HAsO. contents in the solutions remained low at all pH values. However, there was a tendency for AsO." to rise with a increase in the pH value, while there was a tendency for H3AsO: to decrease with a increase in the pH value. At pH 4.5, the contents of H2AsO and HASO in the solutions were 99.05 % and 0.32 %, respectively, with respect to the total amount of As(V). As the pH of the corresponding solutions became alkaline, the H2AsO: content was decreased, while the HAsO:” content was increased. At pH 8, the contents of H2AsO- and HAsO:” were
    8.9 % and 91.08 %, respectively, with respect to the total amount of As(V). Contents of other forms of As(V) were very low at any pH level within the above range, so they were not taken into account. Therefore, AsO:4”, HASO, H2AsO:, and H:AsO4, which were major forms of As(V), would be subjected to analysis of possible toxicity to wheat root elongation at a next step. These results indicate that a change in pH value affected the contents of the various major forms of As(V), and in particular, at acidic pH, H2AsO:" was the highest in content among the major forms, and at basic pH, HAsO: was the highest.
    2. Effects of pH and coexisting anions on As(V) toxicity
    It can be seen from Table 2 that, when the pH was increased from 4.5 to 8.0, EC50{As(V)r}, EC50{As04*}, and EC50{HAsO:”} were increased from 6.88, 0.001, and 0.021 uM to 33.9, 4342, and 27.4 uM, respectively, with a 5-fold, a 4342000-fold, and a 1305-fold increase, respectively.
    Unlike EC50{As(V)r}, EC50{AsO4*}, and EC50{HAsO4}, when the pH was increased from 4.5 to 8.0, EC50{H2As0:} and EC50{H3As0.} were decreased from 6.62 and 41.77 uM to 2.68 and 0.005 uM, respectively, with a 2.5-fold and a 8354-fold decrease, respectively.
    These suggest that the As(V) toxicity was influenced significantly by the pH possibly through transformation among the As(V) forms and competition with OH" alone or in combination.
    According to the theoretical basis of BLM, at high pH, if the OH" activity was linearly dependent on EC50{WO:+}, OH and AsO:* competed with each other for binding to the ligand binding sites.
    The above results suggest that there were mainly two reasons for the change in As(V) toxicity: the pH affects transformation among the As(V) forms, and the HAsO, AsOa4”, H>AsOy4, and H3AsO4 contents varied with the pH.
    With the pH was increased, the activities of HAsO:”, AsOs>, H2AsO:, and H3AsO; were gradually increased.
    Along with this, EC50{AsO4’"} and EC50{HAsO4*"} increased sharply, while EC50{H2As0:} and EC50{H3As0O:} decreased slightly.
    As the pH was increased from 4.5 to 8.0 (from acidic to alkaline), the toxicity of As(V) was enhanced.
    Since OH" did not compete with AsO4, HAsO:%, H:AsO:, and Hs;AsO. for binding to wheat root binding sites, logKorer. was set to 0 (zero). Due to the competition between the coexisting ions of NO: H:PO-, Cl, and SO4% and the various forms of As(V), toxicity thresholds of As(V) in the forms of total As(V), AsOa*, HAsOa%, H2AsOr, and H3AsOs, expressed as EC50{ As(V)T}, EC50{AsOa*}, EC50{HAsO. }, EC50{H2AsO:"}, and EC50{H3AsO:}, varied widely.
    It can be seen from Table 2 that, when the NO: and Cl activities were increased from 0.95 and 1.34 mM to 25.25 and 25.50 mM, respectively, ECS0{AsOs"}, ECS0{HAsO.}, EC50{H>As04}, and EC50{H;AsO4} were not significantly varied.
    As can be appreciated from Table 2 and FIG. 2, when the activity of H2PO: was increased from 044 to 11 mM, EC50{As(V)})} increased linearly from 11.1 to 23.6 uM, and EC50{AsO4}, EC50{HAsO: }, EC50{H2AsO0:}, and EC50{H3AsO4} also increased linearly, from 1.54 nm, 0.971 um, 9.50 pm, and 1.90 nm to 2.77 nm, 1.75 um, 17.10 um,
    and 3.41 nm, respectively; and when the SO4*" activity was increased from 0.40 to 6.56 mM, EC50{As(V)} increased linearly from 10.4 to 17.5 uM, and EC50{As0:},
    2. - . . EC50{HAsO:"}, EC50{H2As04}, and EC50{H3As04} also increased linearly, from
    1.43 nM, 0.903 uM, 8.82 uM, and 1.76 nM to 1.99 nM, 1.26 uM, 12.3 uM, and 2.45 nM, respectively, with a 1.39-fold, a 1.4-fold, a 1.39-fold and a 1.40-fold increase, respectively. From the above results, it is found that HPO: and SOs” competed with AsO:%, HAsO: , H2AsO-, and H3AsQq for binding to wheat root binding sites, while NO: and Cl did not compete with them. So, logKxossr and logKcisr were each set to zero. Table 2 Chemical compositions of test solutions in each run and EC50 values ECS value and god 935: confidence interval Ram : : ECH{EAe0: Ha ECH080.° NG Nara © he BOSH 200008 05 MIS (LIE 0903 (REILONET SEI (SOTGET LINES (161510187010 LO REINO ADIOS) OUIS GMN) ON ERN) LASSIE es kn OD LEH (LZR TT) 008 MASLIN) SED (BISNIS DI 3 LTE (LEGS LOGE (RSSEII6E) ION TLD) LI niee OLEN (Lei LIS (LOTA) MA OIL) LITE Ces.) IS DOREY GLSSSTN LIZE) 136 (LIEN) RE EE 2450 (RISITUIETINY UI LATA (LS LESINT) 0ST (0823-1034) 930 (STO) ON LLS IEN EL LEDS GLD LEI) LOR (LOLLIS UA IBSL112} Lip {Lsegia ze wij IE 1ST QAPICLOMIEY TIE (LIL EEE EE! IRISH (III IIe) LAZ (1281363 HS {Den IJ sr en KOE EEE] IEF EIST) DI EPE EE EE! TI CSE) EADE GINGEN 45 LOL QOTIHOITE-OET SENSIS TED 418 6348.) 58 9010019000100 JONES GNS BT (124150 ZE IHG UISMEE-0.279) T7807 04-863) 481 (SM348] EE LEE 705-6 THY 8 M006 9298 162 [138-189 te = £5 VLAEISININ LEINE 77-1 8188 SINTELS DT 0568-0745) TB MBSA 38-345) EN] DMI A22 PROER-G.A33) 73 TOMBE PRIN 674 36-1531 0.0453 (0.0180-0.856) SD ELN) TEA TI9 DEMISE ZARIS TIG
    3. Optimization of Biotic Ligand Model (BLM) Since the toxicity of the four major forms of As(V), as discussed above, was taken into account, Equation (1) could be transformed into a following Equation (6): j K pon: {4sO: : i Kian HAsO" i Ky son 1, As i+K HL ASOBL iH, ASO} I= PK 46, or ASO + Kian HASO 4K one 1H, AsO HK, om IH ASO Ks gar WH POT} HK pr bSO } Equation (6) The above Formula for calculating the relative root elongation was modified into a following Equation (7): RE = A { East Oe Bp SO Fo yp tts OCB dds) y VE ar BG TT Ep WAO To Kp LISE Eon ELSE Kg pp POS Kr SCN Equation (7) In order to confirm this optimized result, a free ion activity model (FIAM) (Equations (8) to (11)) was introduced here to make a comparison with the BLM. It was further found that, as compared with FIAM, the BLM had an improved capability of predicting the toxicity of a metal to plants.
    RE = 100 _ 7 ; 3-7 NF rol ASO, } ee aa] | | EC30{ 40; 1 Equation (8) 100 | {HAO 1+ = | ECSO{HAsO, } Equation (9) 100 [ {H4507} | 1+] em — | | EC5041,450,7} N +
    Equation (10) 100 RE 5 — Ll 11,450, § | | EC50{H AsO} Equation (11) Wheat root elongation could be influenced by {AsO:*}, {HAsO:”}, {H2AsO:%}, {H3AsO4}, {HPO}, and {SOs}. Since {OH}, {CT}, and {NOs} had no effect on the toxicity of As(V), they were excluded from Equation (6) described above. Parameters shown in Table 3 were obtained through Mathematical Model function of DPS 9.0 software. From Table 3, it can be known that logK.i0s:=3.70, logKr4s0481=4.08, logK'24s0481=4.77, 102Ki3.45048:=6.50, logKrosmr=2.09, and logKso:z=1.86, f ee =0.30, and p=1.73. These results further indicate that, as compared with FIAM, the BLM had an improved capability of predicting the toxicity of a metal to plants, as shown in FIG. 3. Table 3 Fitted parameters by FIAM and BLM Adodal - ® m= ea # ZO Hal Ha: Eee HSO so wf Er Azo 55 DNAS S003 00S DEINE Hiep Za IATA $.02s034 QAR
    FIAN FeAl 82 3.5% REEN SERA Haak za IES BODNSAOMST TART ELAS ATI ARI ATER S50s=R3d LOMI LET LS 3.3% 4.30.52 1.732006 4 Validation of As(V)-BLM To verity the accuracy of the BLM parameters obtained, a back-substitution method was employed to determine an agreement between predicted and measured EC50{AsO:°} and ECS0{HAsO4*}. On the basis of Equation (7), EC50{AsO:*}, EC50{HAsO. }, EC50{H:As047}, and EC50{H3As04} could be respectively expressed as follows:
    2 Í pi ( + K, PÖ BL HPO; J Kgs RL So: - ) EC5044s0} }= a ( 30% { a HAsO; Y= fr | K AsO,BL Kyo aso}, Equation (12) 50% 7 _ { vn Z- _ 2} road + Ky vo EL {#.Po, } + LO 150. b £CH0 {#150} =F) (1 — £5) K + K Usa} AsBL J | aso BL Ast, BE 7 Equation (13)
    EC50{H,As07} u faspi(1 + Ku‚po,s1{H2P07} + Kso,e,{S03}) u 50% AsO3T {HAs027} H3AsO (1 7 fas) (aso 51 + Kaso,BL ee + Kyaso, se 1154507} +Ky As04BL ee) Equation (14) EC50{H;As0,} _ fase + Ki, po, {Ha POLY + Kiso, 21. {S057}) u 50% AsO3™ {HAsO2™} {H,As07} (1 = fot) (aso, + Kaso,BL zi + Kyaso, BL ASO] +Ky, 450,81 tins) Equation (15) Values of Kasossr, Kiasossr, Kiopossr, Ksossr, f oo , and f as shown in Table 3 were substituted into Equations (12) to (15). Then, values of EC50{AsO:*} and of EC50{HAsO4*"} could be obtained from {AsO:°}, {HAsOs*}, {H2As047}, {H3As04}, {HoPO:}, and {SO4*}. As can be appreciated from FIG. 5, predicted values of EC50{As04%} and EC50{HAsO4>"} through the BLM were within 2 times the measured values thereof.
    It can be seen from Table 3 and FIG. 4 that, when the toxicity of As(V) to wheat root elongation was predicted by using FIAM-AsO4%, FIAM-HAsO%, FIAM-H2AsO-, and FIAM-H3As0O:, the RMSE value was 23.45, 15.75, 8.58, and 15.33, respectively, and R was 0.55, 0.80, 0.92, and 0.81, respectively.
    In contrast, the As(V)-BLM took into account competition between the various forms of As(V) and the coexisting anions, and thus had an improved capability of predicting the toxicity of As(V) to wheat root elongation, with RMSE being 4.71, R being 0.98, and Sia consistent with the wheat root elongation at inhibition. Relationships between the values of EC50{AsO:, EC50{HAsO4*}, EC50{H2As047}, and EC50{H;AsO,4} and the HoPO:+ and SO:” activities, as shown in Equations (12) to (15) and in FIG. 5, suggest that HPO. and SO4* competed with the four forms of As(V) for binding to the wheat root ligand. The results further strengthen our conclusion that AsO4*, HAsO:%, HaAsOr, and HzAsOy were toxic forms of As(V) and HoPO: and SO competed with them for binding to the wheat root ligand.
    From the foregoing, the pH significantly affected the activities of total As(V), AsOs™, HAsO:, H>AsOs, and H3AsOs, expressed as ECS50[As(V)r], ECS50{AsO.*}, EC50{HAs0: }, EC50{H»As047}, and EC50{H;As0.}, respectively. In particular, As the pH was increased, EC50[As(V)1] exhibited a 4.91-fold increase. The pH of equal to or greater than 7.0 had no effect on EC50{ AsO4*"}. This was an indicator indicating a non-competitive inhibition based on the BLM theory and indicating that OH" was less likely to compete with the various forms of As(V) for binding to the wheat root ligand. In addition, there was no linear correlation between the OH activity and EC50{AsO4*}, EC50{HAsO4*"}, EC50{H2AsO0:}, and EC50{HzAsO}, further indicating that OH" did not compete with AsOa*, HAsO, HaAsO:, and H3AsOs for binding to the wheat root binding sites. Hence, in view of the non-competitive inhibition, a rational explanation of the observed effects of the pH of 4.5 to 8.0 on the As(V) toxicity is the change in the As(V) forms. As(V) was present in the solutions mainly as AsO4*, HAsO4”, H2AsOy, and H3AsO:. In the case of a strongly alkaline or neutral solution, when the pH was decreased, H2AsO: dominated; while when the pH was increased, the HAsO4 content increased.
    In Example 1, EC50{As(V)r} was increased from 6.88 to 33.9 uM, and the As(V) toxicity decreased as the pH became alkaline. At the pH of 6.0 to 8.0, the AsOa4* and H;AsO4 contents were low. While there was a tendency for AsO4 to rise with a increase in the pH value, and there was a tendency for H;AsOj to decrease with a increase in the pH value. At pH 4.5, the content of H>AsO4™ was high. As the pH was increased from
    4.5, the HoAsO- content decreased significantly. In contrast, at pH 4.5, the content of
    HAsO: was very low, and as the pH was increased, the HAsO4” content increased significantly, the value of ECS50{As(V)r} increased gradually, and the As(V) toxicity decreased gradually. These results suggest that H3AsO: had a strongest toxicity, H2AsOy and HASO” had a medium toxicity, and AsO:4* had a weakest toxicity. Table 3 shows that the complexing stability constant of H2AsO:" for the wheat root ligand was higher than those of AsO4* and HAsO4* for the wheat root ligand. This indicates that H2AsO- was more likely to bind to the wheat root ligand. It can also be seen that the complexing stability constant of Hz AsOy for the wheat root ligand was 1.36-fold of or 1.36 times that of H2AsOy™. Thus, the toxicity of H3AsO: was stronger than that of H2AsO:".
    H:POr and SO enabled the toxicity of As(V) to wheat root elongation to be significantly reduced, and H:PO- had such a capability greater than SO4>". The HaPOr activity and the EC50 values of AsOs*, HAsO:%, H2AsOs, and H3AsO: had a relationship in which both of them increase linearly, and the SO4*" activity and the EC50 values of AsOs*”, HAsO4”, H2AsOr, and H3AsO also had such a relationship. This suggests that HoPO: and SO enabled the toxicity of As(V) to be reduced. However, there was no linear correlation between the NO: and Cl activities and the EC50 values of AsOa*, HAsOa%, HaAsO-, and H3AsO4, so NO: and CT were less likely to compete with these As(V) forms.
    All the above studies show that both H;PO and SO could buffer the toxicity of As(V).
    Based on the BLM theory, the complexing stability constant of HPO for the wheat root ligand (logK+2r048:=2.09) was much higher than that of SO:” (logK'so:8:=1.86), indicating that HoPO- and SO enabled the toxicity of As(V) to be reduced. Moreover, HPO: had a higher affinity than SO4%, which further indicates that H+PO: could better buffer the toxicity of As(V) as compared with SO”. HPO: and SO: may compete with the various As(V) forms for binding to wheat root binding sites, and H2PO: was more capable of inhibiting wheat root elongation as compared with SO4%.
    From the above, AsO4*, HAsO:%, H2AsO:, and H3AsO: were regarded as toxic forms of As(V), and competed with H>PO: and SO4*" for binding to biological ligand binding sites, which was incorporated into the BLM. Further, BLM parameters were derived and verified. The developed BLM exhibited a good capability of predicting the acute toxicity of As(V) to wheat root elongation, and is believed to be an accurate predictor of the toxicity of As(V) to wheat root elongation. However, soil in nature contains numerous ingredients, and organic matters, heavy metals, and organic colloids present therein may affect the application of the As(V)-BLM. In addition, substances secreted by the plant root system and accumulated in soil and microbial activities may also affect the toxicity of As(V) to plants. So, before application of the As(V)-BLM in soil risk assessment, dissolved organic matters and competing ions in field soil should be determined. The As(V)-BLM is expected to be promising in soil risk assessment. Further, as can be appreciated from FIG. 5, the predicted EC50 values by the As(V)-BLM were within two times the measured values.
    The invention is described above based on preferable embodiments. It will be apparent to those skilled in the art that various improvements and embellishments can be made without departing from the concept of the invention, and should fall within the scope of the invention as defined by the appended claims.
    权利要求:
    Claims (3)
    [1]
    A method for predicting arsenic toxicity in wheat root elongation, the method comprising the steps of: a. determining concentrations of AsO4*, HAsO:%, H2AsO2 , H3AsO4, H2POr and SO4% in a soil for growing wheat, where the concentrations are expressed in the same unit; and B. substituting the determined values of the AsO:*, HAsOs*, HoAsOr, H3AsO4, HoPOr and SO4* concentrations in Formula (I) to calculate relative root elongation; ee gn EHO No REIN HIN De oii od LET eo ER En WAIN ce WE OT IN BR NTR Formula (I) where, RE represents the relative root elongation, logKasossr = 3.48 — 3.92, logKuasosr. = 3.96 — 4.20, logKmzas048, = 4.64 — 4.79, logKm3as048 = 6.14 — 6.86, logKuzpousr = 1.97 — 2.21, logKsoaa = 1.64 — 2.08, 52% = 0.28 -0.32, B = 1.67 — 1.79; and {AsO4*}, {HAsO4}, {H2AsO:}, {H3AsO4}, {H2POr}, and {SO: } respectively the determined values of the AsO4*-, HAsO: -, HoAsO:-, H3AsO4- represent H:PO: and SO4* concentrations.
    [2]
    The method of claim 1, wherein step (b) further comprises substituting the determined values of the AsO:*, HAsO4 =, H2AsO:, H3AsO4, HoPO: and SO: concentrations, obtained in the step (a), in formulas (II) — (V) to give EC50 of AsOsò, HAsO:, respectively, H2AsO; and H3AsO: to calculate on root system of wheat; 8 ti YES! Rast BL RRA0 BL ron HRM ASOBL ry a= YH As Rab LT omy | Formula (II)
    -21- ear Ten FES IFE, po rH POT ME npr 5017] ESHA je =~ £ ie i, - Edgy (Hpi, yo _ {HpdsDgil (Ase | Faron 80 Rast Bin sum HH a de0 BL uncle: YR Ha 8o0. Bl omy | Formula (II) ‚ ne fait (ey po mH P04 Keg ar isol—}) ECStHH- Adi x Ts e205 if EE.ds. Bl +E 58 (ABTS Ee oes and Sz sies | iT TAsEL! | LH AE (BLT ARS BLT men) y Es Ha 8ofe BLE AgojT | Formula (IV) 58% Vip ~ NTE A mr ien2— 1 ECSOH,AsD,} = el na NN = ; coo a LL [Asi] | Hamit: {Heal [ Iasi] LE Hose RLY Bare, PUR ass! HAS BLY Fly: TH Heist EL Hast, tj Formula (V) where in the formulas (IT) — (V), logKasossr = 3.48 — 3.92, logKnasossr = 3, 96 — 4.20, logKn24s048 = 4.75 — 4.79, logKn3as048L = 6.14 — 6.86, logKuzpo4eL = 1.97 — 2.21, - 0, - 3. - logKsossr = 1.64 — 2 ,08, 524, = 0.28 -0.32, p= 1.67 — 1.79; and {AsO:*}, {HAsOQ4>), - .27 .. (H2AsO:}, {H3AsO4} , {H2PO4'}, and {SOs} represent the determined values of 1 > x $a > 5 the AsO:>-, HAsO =, H2AsO:-, H3AsO:-, HoPOy- and SO4 concentrations, respectively.
    [3]
    Method according to claim | or 2, wherein the wheat variety includes Jimai 22, Jimai 23, Jimai 44 and Yanmai 1212.
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    公开号 | 公开日
    NL2028028B1|2021-10-14|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    CN106916213B|2015-12-25|2020-04-21|中国农业大学|Protein AsT, coding gene thereof and application thereof in plant stress tolerance|
    CN106932538A|2017-03-29|2017-07-07|南京大学|A kind of nickel ion is to the Forecasting Methodology of wheat root elongation toxicity and its application in soil|
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