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Although Chinese cultural beliefs highlight the significant role of fathers in educating and disciplining their children, little empirical research has explored the role of Chinese fathers more broadly on child adjustment. This study used survey methodology to examine the effect of father involvement, fathering practices, and father-child relationships on child adjustment in Mainland China. Participants were 609 mother-father dyads with at least one child aged 3 to 7 years in preschool. Fathers reported on their involvement and relationships with their children and fathering practices, and mothers reported on child adjustment. Results indicated that paternal inconsistency, coercive parenting, and father-child relationships were significant predictors of behavioral and emotional problems in children. Father involvement, positive encouragement, and father-child relationships were significantly associated with child competencies (positive child behaviors). Additionally, paternal inconsistency and father-child relationships moderated the relationship between father involvement and child behavioral and emotional problems. At low levels of paternal inconsistency, higher father involvement was related to lower behavioral and emotional problems in children; yet, at high levels of paternal inconsistency, higher father involvement was associated with higher behavioral and emotional problems. When father-child relationships were poor, higher father involvement was also related to more behavioral and emotional problems. The findings highlight the importance of considering both the quantity and quality of fathering in child development. When combined with poor fathering practices, increased father involvement may not be beneficial and could potentially be harmful for child adjustment.

This study aimed to develop and evaluate a new parent-report measure to assess primary schoolchildren’s academic behaviors in the home context. We developed the Academic Behavior Scale (ABS) and administered it to Chinese parents of primary schoolers along with other measures. Six hundred and forty-five parents and 170 primary schoolchildren in Grades 4–6 were recruited from a public primary school and completed a set of questionnaires. After that, the psychometric properties of the ABS including factorial validity, convergent and concurrent validity, as well as internal consistency were evaluated using confirmatory factor analysis and correlation analysis in Mplus v.8.3. The results confirmed a two-factor structure for the scale, with satisfactory convergent and concurrent validity and internal consistency. This study provides preliminary evidence for the satisfactory psychometric properties of the ABS among Chinese parents.

This study aimed to evaluate the psychometric properties of the Fears of Compassion Scales (FCS) in a Chinese cultural context. Six hundred eighty-four undergraduate students from a university in Fujian Province completed a set of questionnaires including the FCS, Depression, Anxiety, and Stress Scale (DASS-21) and Self-acceptance Questionnaire (SAQ). Confirmatory factor analysis (CFA), Exploratory Structural Equation (ESEM) and other statistic approaches were conducted to investigate the psychometric properties of the FCS. The three models of one-factor structure for each subscale of the FCS and the final model of the three-factor structure with 31 items showed good fit to the data. Seven items of the FCS did not show adequate psychometric characteristics and were thus removed from the scale. Moreover, fears of compassion (for others, from others, and for self) were positively correlated with depression, anxiety, and stress, and were negatively associated with self-acceptance and self-evaluation as expected. The FCS had good internal reliability, acceptable factorial validity, and satisfactory criterion-related validity in a Chinese sample. This study provides relatively strong support for the FCS as a promising instrument for use in future research and practice with Chinese populations.

This study attempted to examine the mediating role of filial piety in the relationships between parental autonomy support and control and Chinese adolescents’ academic autonomous motivation. A set of questionnaires were administered to 492 adolescent students at two senior high schools in Fuzhou, China. Confirmatory Factor Analysis and Structural Equation Modeling were employed to analyze the data. The results showed that reciprocal filial piety (RFP) fully mediated the relationships of parental autonomy support and behavioral control with adolescents’ academic autonomous motivation. RFP did not significantly mediate the relationship between psychological control and academic autonomous motivation. Comparatively, authoritarian filial piety (AFP) did not play a significant mediating role in the relationship between the three parenting dimensions and adolescents’ academic autonomous motivation. The findings provide a new perspective for understanding the relationship between parenting behaviors and Chinese adolescents’ academic autonomous motivation.

Background: Forest ecosystems play a crucial role in global carbon cycle. Identifying bio- or abio- drivers on forest biomass allocation pattern could improve our understanding in forest carbon sink, stock and cycle across various spatio-temporal scales. Through compiling a dataset (n=1931) of the root-shoot ratio from previous studies, here we implemented the Random Forest algorithm (RF) to elucidate main driven factors on the root-shoot ratio across China forest ecosystems. Results: (1) Forest age and forest density were both contributed mostly to root-shoot ratio variations regardless of forest origins (natural or planted forests). The relative important values (% increase in MSE) for forest density and forest age on the root-shoot ratio were 54.42% and 51.05% in the natural forests, and 74.61% and 117.27% in the planted forests, respectively; (2) Compared to soil variables (soil texture and nutrient status), climatic variables (temperature and precipitation) showed stronger effects on the root-shoot ratio; (3) Partial dependent analysis further demonstrated that root-shoot ratio initially decreased with forest age, but afterwards increased to a relative stable level (the turning point, e.g., ca. 150 yr for natural forests and ca.30 yr for planted forests); (4)The root-shoot ratio increased nonlinearly with an increase of forest density in both forest types. Forest density and precipitation seasonality exerted positively direct effects, while forest age together with temperature seasonality, mean temperature of wettest quarter and precipitation of warmest quarter had negatively effects on the root-shoot ratio of two forest types. Conclusions: The forest age, forest density and climate seasonality contributed mostly to variations of root-shoot ratios in China forest ecosystems. These results would improve our understanding of environmental drivers on forest biomass allocation over a large spatial scale, and to some extent provide a generally practical significance in forest management (e.g., time for timber harvest), although species-specific root-shoot ratio associated with ontogeny should be further investigated in the future.

This study validated a parent-report measure of the Parenting and Family Adjustment Scales in a Chinese cultural context through investigating 650 Chinese parents. The results provided evidence for satisfactory reliability and validity of Parenting and Family Adjustment Scales in a Chinese context, which is thus promising to be used for Chinese parents.

This study investigated the effect of social economic status and parents’ rearing behavior on social creativity of children in Mali. Demographic information, social creativity measure, parent behaviors measures were used. The results indicated that: (1) In the social creativity, the difference was not significant between males and females and their parenting behaviors; (2) There had significant differences of scores of social creativity, parenting behaviors among different grades; (3) Social creativity was correlated significantly and positively with home income, parents rearing, and mother’s works; (4) Grades and fa-ther’s rejection could significantly and positively predict children’s social creativity. Higher social economic status and parents’ rearing behavior help to encourage children’s social creativity.

This study aimed to validate a parent-report measure of child adjustment and parenting efficacy (Child Adjustment and Parent Efficacy Scale [CAPES]) in a Chinese cultural context. Six hundred and fifty Chinese parents in China participated in the study and completed a set of questionnaires including the CAPES, the Strengths and Difficulties Questionnaire (SDQ), the Parenting Sense of Competence Scale (PSOC), and the Parenting and Family Adjustment Scales (PAFAS). The factorial, convergent, and concurrent validity as well as internal consistency were evaluated. The results provided support for a new 2-factor structure of child behavioral and emotional adjustment. The 1-factor structure of parenting efficacy was confirmed. The three constructs obtained satisfactory internal consistency. Moreover, the CAPES scores correlated significantly with the SDQ, PSOC, and PAFAS in the expected pattern, which indicated its excellent convergent and concurrent validity. Therefore, it is a promising measure, due to its brevity and comprehensiveness, with the first indications of satisfactory internal consistency and validity among Chinese parents. However, a revision of the instrument is needed to avoid the ordering effects of positive and negative items, and further hypothesis-driven research is also needed to validate the (revised) instrument in different Chinese samples.

The extensive applications of ZnO nanoparticles (nano ZnO) and dimethoate (DM) have increased the risk of humans' co-exposure to nano ZnO and DM. Here, we report the synergistic effect of nano ZnO and DM on their biodistribution and subacute toxicity in mice. Nano ZnO and DM had a synergistic toxicity in mice. In contrast, bulk ZnO and DM did not cause an obvious synergistic toxicity in mice. Although nano ZnO was low toxic to mice, coexposure to nano ZnO and DM significantly enhanced DM-induced oxidative damage in the liver. Coadministration of nano ZnO with DM significantly increased Zn accumulation by 30.9 ± 1.9% and DM accumulation by 45.6 ± 2.2% in the liver, respectively. The increased accumulations of DM and Zn in the liver reduced its cholinesterase activity from 5.65 ± 0.32 to 4.37 ± 0.49 U/mg protein and induced hepatic oxidative stress. Nano ZnO had 3-fold or 2.4-fold higher binding capability for serum albumin or DM, respectively, than bulk ZnO. In addition, serum albumin significantly increased the binding capability of nano ZnO for DM by approximately four times via the interaction of serum albumin and DM. The uptake of serum albumin- and DM-bound nano ZnO by the macrophages significantly increased DM accumulation in mice. Serum albumins play an important role in the synergistic toxicity of nano ZnO and DM. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1202-1212, 2017.

The extensive applications of ZnO nanoparticles (nano ZnO) and dimethoate have increased the risk of people's coexposure to nano ZnO and dimethoate. Therefore, we evaluated in this study the effects of nano or bulk ZnO on dimethoate-induced toxicity in mice. The serum biochemical parameters, biodistributions, oxidative stress responses, and histopathological changes in mice were measured after intragastric administration of nano or bulk ZnO and/or dimethoate for 14 days. Oral administration of nano or bulk ZnO at a dose of 50 mg/kg did not cause obvious injury in mice. In contrast, oral administration of dimethoate at a dose of 15 mg/kg induced observable oxidative damage in mice. Co-administration of nano or bulk ZnO with dimethoate significantly increased Zn accumulation by 30.7 ± 1.7% or 29.7 ± 2.4% and dimethoate accumulation by 42.8 ± 2.1% or 46.6 ± 2.9% in the liver, respectively. The increased accumulations of dimethoate and Zn in the liver reduced its cholinesterase activity from 5.64 ± 0.45 U/mg protein to 4.67 ± 0.42 U/mg protein or 4.76 ± 0.45 U/mg protein for nano or bulk ZnO, respectively. Furthermore, the accumulations of dimethoate and Zn in liver also increased hepatic oxidative stress, resulting in severe liver damage. Both nano and bulk ZnO dissolved quickly in acidic gastric fluid, regardless of particle size; therefore, they had nearly identical enhanced effects on dimethoate-induced toxicity in mice.

Silica nanoparticles (SiNPs) are now in daily use due to their low intrinsic toxicity. Cadmium is a ubiquitous environmental pollutant. In spite of real risk of humans' co-exposure to SiNPs and cadmium, their synergistic toxicity is still unclear. Here, we report the synergistic effects of SiNPs and CdCl₂ on their biodistribution and subacute toxicity in mice. The biodistributions, histopathological changes, serum biochemical parameters and oxidative stress responses were determined after intraperitoneal injection of SiNPs and/or CdCl₂ to mice. SiNPs and CdCl₂ have a positive synergistic toxicity in mice. Although SiNPs were low toxic to mice, co-exposure of SiNPs and CdCl₂ significantly enhanced CdCl₂-induced oxidative damage in the liver as indicated by the severe liver dysfunction and histopathological abnormalities. Co-exposure to SiNPs and CdCl₂ markedly increased the cadmium accumulation in the liver, which induced significant hepatic oxidative stress. In vitro binding assays indicated that serum albumin and Cd(2+) mutually enhanced the binding of each other to SiNPs via the interaction of serum albumin and Cd(2+). The uptake of serum albumin- and Cd(2+)-bound SiNPs by the macrophages significantly increased cadmium accumulation in mice. These results demonstrate that serum albumins play an important role in the positive synergistic toxicity of SiNPs and CdCl₂.

CaMAl 12-x O 19 : x Mn 4+ (M is one or more of K + , Na + , Li + ) materials were prepared by a combustion method in air atmosphere. The Mn concentration, the influence of one or more alkali-chloride on luminescence properties, crystal phases and surface morphology of the samples were investigated. The fluorescence intensity of CaAl 11.98 O 19 :0.02Mn 4+ modified by combining three kinds of alkali-chloride can be enhanced by three times. Blue shift of CaMAl 12-x O 19 : x Mn 4+ luminescence is explained from the point of view of enhancing electron cloud deformation after doping. Alkali metal ions were beneficial to form hexagonal CaAl 12 O 19 while there was certain inhibition to other peak strengths. The mechanism is the coexistence of alkali-chloride replacing Al 3+ or Ca 2+ instead of Mn 2+ based on the difference of cation radius, this would increase the luminous centre of Mn 4+ and provide charge compensation at the same time. The size of red phosphors was 5-10 μm, which is useful for light emitting diode applications.

A novel non-hemorrhagic metalloproteinase, AHPM, was purified from the venom of Agkistrodon halys pallas by a combination of ion-exchange and gel filtration chromatography. AHPM is a dimeric glycoprotein with multiple pIs around pH 7.9 and has a molecular mass of 110 kDa with two blocked N-terminuses. Partial sequence of AHPM obtained by LC-MS/MS analysis together with its dimeric nature reveals that it is a P-IIIc snake venom metalloproteinase composed of metalloproteinase, disintegrin-like and cysteine-rich domains. AHPM has a conserved DECD sequence in the disintegrin-like domain. AHPM hydrolyzes casein and fibrinogen and also dissolves fibrin clots and the proteolytic activity is abolished by EDTA, but not by PMSF, suggesting that it is a metalloproteinase. The protease hydrolyzes rapidly the Aα-chain of fibrinogen followed by the Bβ-chain and does not cleave the γ-chain. AHPM contains endogenous Zn 2+ and Ca 2+ ions at a molar ratio of 1:1.9 and 1:4.2, respectively, and Zn 2+ ions are essential for its proteolytic activity. AHPM inhibits collagen-and ADP-induced platelet aggregation with half maximal inhibitory concentrations of 200 ± 8 nM and 280 ± 10 nM, respectively. EDTA markedly attenuates the inhibition of ADP-induced platelet aggregation by AHPM, indicating that the fibrinogenolytic activity of AHPM is involved in its inhibition of ADP-induced platelet aggregation. AHPM is devoid of hemorrhagic activity when injected (up to 30 μg) subcutaneously into mice. AHPM is so far identified as first non-hemorrhagic P-IIIc SVMP which has both fibrinolytic and platelet aggregation-inhibition activities. The bifunctional enzyme may have a potential clinical application as a thrombolytic agent.

Anticoagulation factor II (ACF II), a coagulation factor X- binding protein from the venom of Agkistrodon acutus has both anticoagulant and hypotensive activities. Previous studies show that ACF II binds specifically with activated factor X (FXa) in a Ca2+-dependent manner and inhibits intrinsic coagulation pathway. In this study, the inhibition of extrinsic coagulation pathway by ACF II was measured in vivo by prothrombin time assay and the binding of ACF II to factor IX (FIX) was investigated by native polyacrylamide gel electrophoresis and surface plasmon resonance (SPR). The results indicate that ACF II also inhibits extrinsic coagulation pathway, but does not inhibit thrombin activity. ACF II also binds with FIX with high binding affinity in a Ca2+-dependent manner and their maximal binding occurs at about 0.1 mM Ca2+. ACF II has similar binding affinity to FIX and FX as determined by SPR. Ca2+ has a slight effect on the secondary structure of FIX as determined by circular dichroism spectroscopy. Ca2+ ions are required to maintain in vivo function of FIX Gla domain for its recognition of ACF II. However, Ca2+ at high concentrations (>0.1 mM) inhibits the binding of ACF II to FIX. Ca2+ functions as a switch for the binding between ACF II and FIX. ACF II extends activated partial thromboplastin time more strongly than prothrombin time, suggesting that the binding of ACF II with FIX may play a dominant role in the anticoagulation of ACF II in vivo. © 2012 Wiley Periodicals, Inc. Biopolymers 97: 818–824, 2012.

Anticoagulation factor I (ACF I), a snake C-type lectin (snaclec) from the venom of Agkistrodon acutus binds specifically with activated factor X (FXa) in a Ca2+-dependent manner and prolongs the blood-clotting time in vitro. In this study, the inhibition of the coagulation pathway by ACF I was measured in vivo by activated partial thromboplastin time and prothrombin time assays and the binding of ACF I to factor IX (FIX) was investigated by native PAGE and surface plasmon resonance. The results indicate that ACF I inhibits both intrinsic and extrinsic coagulation pathways, but does not inhibit thrombin activity. ACF I also binds FIX in a Ca2+-dependent manner and their maximal binding occurs at 0.25 mM Ca2+. ACF I has a higher binding-affinity to FIX than to FX. Ca2+ is required to maintain in vivo function of FIX Gla domain for its recognition of ACF I. However, Ca2+ at high concentrations (>0.25 mM) inhibits the binding of ACF I to FIX. Ca2+ functions as a switch for the binding between ACF I and FIX. The results suggest that the binding of ACF I with FIX may play a dominant role in the anticoagulation activity of ACF I in vivo.

The extensive applications of ZnO nanoparticles (nano ZnO) and dimethoate (DM) have increased the risk of humans' co-exposure to nano ZnO and DM. Here, we report the synergistic effect of nano ZnO and DM on their biodistribution and subacute toxicity in mice. Nano ZnO and DM had a synergistic toxicity in mice. In contrast, bulk ZnO and DM did not cause an obvious synergistic toxicity in mice. Although nano ZnO was low toxic to mice, coexposure to nano ZnO and DM significantly enhanced DM-induced oxidative damage in the liver. Coadministration of nano ZnO with DM significantly increased Zn accumulation by 30.9 ± 1.9% and DM accumulation by 45.6 ± 2.2% in the liver, respectively. The increased accumulations of DM and Zn in the liver reduced its cholinesterase activity from 5.65 ± 0.32 to 4.37 ± 0.49 U/mg protein and induced hepatic oxidative stress. Nano ZnO had 3-fold or 2.4-fold higher binding capability for serum albumin or DM, respectively, than bulk ZnO. In addition, serum albumin significantly increased the binding capability of nano ZnO for DM by approximately four times via the interaction of serum albumin and DM. The uptake of serum albumin- and DM-bound nano ZnO by the macrophages significantly increased DM accumulation in mice. Serum albumins play an important role in the synergistic toxicity of nano ZnO and DM. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1202-1212, 2017.

The increase of coverage of forest/vegetation is imperative to improve the environment in dry-land areas of China, especially for protecting soil against serious erosion and sandstorms. However, inherent severe water shortages, drought stresses, and increasing water use competition greatly restrict the reforestation. Notably, the water-yield reduction after afforestation generates intense debate about the correct approach to afforestation and forest management in dry-land areas. However, most studies on water-yield reduction of forests have been at catchment scales, and there are few studies of the response of total evapotranspiration (ET) and its partitioning to vegetation structure change. This motivates us to learn the linkage between hydrological processes and vegetation structure in slope ecosystems. Therefore, an ecohydrological study was carried out by measuring the individual items of water balance on sloping plots covered by different vegetation types in the semiarid Liupan Mountains of northwest China. The ratio of precipitation consumed as ET was about 60% for grassland, 93% for shrubs, and >95% for forestland. Thus, the water yield was very low, site-specific, and sensitive to vegetation change. Conversion of grassland to forest decreased the annual water yield from slope by 50-100 mm. In certain periods, the plantations at lower slopes even consumed the runon from upper slopes. Reducing the density of forests and shrubs by thinning was not an efficient approach to minimize water use. Leaf area index was a better indicator than plant density to relate ET to vegetation structure and to evaluate the soil water carrying capacity for vegetation (i.e., the maximum amount of vegetation that can be supported by the available soil water for an extended time). Selecting proper vegetation types and plant species, based on site soil water condition, may be more effective than the forest density regulation to minimize water-yield reduction by vegetation coverage increase and notably by reforestation. Finally, the focuses in future research to improve the forest-water relations in dry-land areas are recommended as follows: vegetation growth dynamics driven by environment especially water conditions, coupling of ecological and hydrological processes, further development of distributed ecohydrological models, quantitative relation of eco-water quota of ecosystems with vegetation structures, multi-scaled evaluation of soil water carrying capacity for vegetation, and the development of widely applicable decision support tools. © 2008 American Water Resources Association.

The phosphodiesterases (PDEs) are a superfamily of enzymes that have multiple roles in extracellular nucleotide metabolism and in the regulation of nucleotide-based intercellular signaling. Here we describe for the first time the isolation and partial characterization of a novel phosphodiesterase from Trimeresurus stejnegeri venom, named TS-PDE, using ion exchange and gel filtration chromatography. The purified TS-PDE is shown to be homogeneous as judged by SDS-PAGE and capillary isoelectric focusing. TS-PDE is a glycoprotein which contains 2.48% carbohydrate. Unlike other PDEs which are usually single polypeptide chain proteins with isoelectric points between 7.5 and 10.5, TS-PDE is a disulfide-linked heterodimer with an isoelectric point of 5.1 and a molecular mass of 100 kDa. The N-terminal amino acids of two chains are valine and serine, respectively. Furthermore, among all identified PDEs, only TS-PDE contains both of endogenous Cu(2+) and Zn(2+) which are essential for its phosphodiesterase activity. The purified TS-PDE exhibits broad phosphodiesterase substrate range with the order of specificity: nicotinamide guanine dinucleotide > ATP > nicotinamide adenine dinucleotide > ADP. The purified TS-PDE shows an exonuclease activity and no contamination with either alkaline phosphatase or 5'-nucleotidase activity. TS-PDE strongly inhibits ADP-induced platelet aggregation in human platelet-rich plasma by hydrolyzing ADP. Altogether, these results indicate that the novel TS-PDE is a unique phosphodiesterase with different structure from the known PDEs.

Canopy interception is an important hydrological process in forest ecosystem, and its modelling is of significance to understand and estimate the rainfall interception by the canopy. In this paper, a canopy rainfall interception model was established by dividing a rain incident into a set of short period, calculating the rainfall distribution intercepted by the canopy, and educing the process of the rain incident. This model considered the effects of the dryness of canopy and trunk on the evaporation from wet canopy and trunk during one rain incident, and introduced two factors, leaf area index (LAI) and surface area of trunk per unit area of ground (SAI), when computing the evaporation. The application of the model to simulate the rainfall interception process in a Larix principis-rupprechtii plantation in Guyuan, south Ningxia Hui autonomous region of China showed that the simulated and measured throughfall were identical, and the absolute deviation between simulated and measured results was within +/- 1 mm. But, when the precipitation was smaller than 6 mm, the simulated throughfall was lower than the measured one. The values of simulated stemflow were lower than the measured values, and the relative deviation between simulated and measured values was smaller when the precipitation was larger. The process of throughfall in the forest was also simulated, with the results fitted well to the measured one.

With heat dissipation probe technique and combined with microlysimeter and hydrological methods, this paper studied the evapotranspiration of secondary Quercus liaotungensis and Tilia paucicostata stands, and its relationship to forest structure from August to September 2004. The results indicated that the stem sap flux density (SFD) of Quercus liaotungensis and Tilia paucicostata changed regularly from day to night in later growth season. In relatively still period (nighttime), the SFD kept low values continuously, usually below 0.05 microl x cm(-2). min(-1), while in active period (daytime), it increased quickly, usually below 0.25 microl x cm(-2) x min(-1). The daily transpiration of whole-tree was estimated based on the calculation of daily cumulative SFD, which showed that there existed a significant difference between two tree species. The daily transpiration of Quercus liaotungensis reached 5.31 and 2.48 L x d(-1) in sunny- and cloudy-days, 2.35 and 3.75 folds as that of Tilia paucicostata, respectively. There was no significant difference in daily leaf transpiration rate between these two shrub species. During measurement periods, the average daily stand evapotranspiration was 1.45 mm x d(-1), including transpiration (0.72 mm x d(-1)), soil evaporation (0.19 mm x d(-1)), and canopy interception (0.54 mm x d(-1)), which accounted for 49.6%, 13.3% and 37.1% of the total evapotranspiration, respectively. The results showed that the difference of whole-tree transpiration between tree species contributed significantly to the difference of tree canopy transpiration, while the difference of shrub canopy transpiration was on account of the leaf amount in the canopy. The effects of vertical layers in the stand on total stand evapotranspiration also differed, with a percentage of 65.8%, 20.9% and 13.3% for tree canopy, shrub canopy and floor, respectively, which meant that the transpiration and interception of tree canopy contributed most to the total evpotranspiration, followed by shrub transpiration, soil evaporation, and grass transpiration.

Obviously different from the other known phosphodiesterases, the phosphodiesterase from Trimeresurus stejnegeri venom (TS-PDE) consists of two different chains linked with disulfide bonds and contains both endogenous Cu(2+) and Zn(2+). Cu(2+) and Zn(2+) are important for its phosphodiesterase activity. In this study, the effects of metal ions and small-molecule reductants on its structure and activity have been investigated by polyacrylamide gel electrophoresis, high performance liquid chromatography, fluorescence and electron paramagnetic resonance spectroscopy. The results show that TS-PDE has one class of Zn(2+) binding site and two classes of Cu(2+) binding site, including the high affinity activator sites and the low affinity sites. Cu(2+) ions function as a switch for its phosphodiesterase activity. The catalytic activity of TS-PDE does not have an absolute requirement for Cu(2+) and Zn(2+). Mg(2+), Mn(2+), Ni(2+), Co(2+) and Ca(2+) are all effective for its phosphodiesterase activity. TS-PDE has seven disulfide bonds and ten free cysteine residues. l-Ascorbate inhibits the phosphodiesterase activity of TS-PDE through reduction of the Cu(2+), while dithiothreitol, glutathione and tris(2-carboxyethyl)phosphine inhibit the phosphodiesterase activity of TS-PDE by reducing both the Cu(2+) and disulfide bonds. The catalytic activity of TS-PDE relies on its disulfide bonds and bimetallic cluster. In addition, biologically-relevant reductants, glutathione and l-ascorbate, have been found to be endogenous inhibitors to the phosphodiesterase activity of TS-PDE.