Self-assembly of a unique triangle-like tungstovanadate containing pentagonal {(WO7)W3(SnR)2} cluster.

In aqueous solution, a novel triangle-like tungstovanadate estertin derivative K10H10.5[(W4O15(H2O)2){(SnCH2CH2COO)2(V0.75W10.75/V0.25O39)}{{(SnCH2CH2COO)2(µ-OH)}2(SnCH2CH2COO)(VW10O37)}2]·31H2O ((SnR)8-V3W35, R = CH2CH2COO) was assembled by a conventional synthetic method. (SnR)8-V3W35 is composed of one [VW11O39]7- ({VW11}) and two [VW10O37]9- ({VW10}) units connected by eight [Sn(CH2)2COO]2+ groups and a {W4O19} cluster. Interestingly, there exists a pentagonal bipyramid WO7 polyhedral center surrounded by two SnCO5 and three WO6 octahedra, forming a pentagonal {(WO7)W3(SnR)2} cluster in this polyoxometalate (POM), which is also the first example of a pentagonal structure formed by transition metals (TMs) and main group organometals in the POM family. Furthermore, the structure of this organic-inorganic hybrid POM also exhibits the largest number of organotin groups introduced into the POM system. It was characterized with various physico-chemical and spectroscopic methods, including X-ray single crystal and powder diffraction analysis, 119Sn and 51V NMR, IR, thermal gravimetric analysis (TGA), etc. In addition, the catalytic activity of (SnR)8-V3W35 as a mimic of peroxidase was evaluated using o-phenylenediamine (OPD) as a peroxidase substrate. The major factors influencing the oxidation reaction such as pH, the dosage of (SnR)8-V3W35, and concentrations of OPD and H2O2 were mainly studied. (SnR)8-V3W35 exhibits good peroxidase-like catalytic activity. From another perspective, the successful acquisition of (SnR)8-V3W35 further proves the instability and easy reassembly characteristics of TM-sandwich-type tungstovanadates, which also provides a new assembly strategy for synthesizing POM-estertin derivatives.

Molecular characterization of a flavanone 3-hydroxylase gene from citrus fruit reveals its crucial roles in anthocyanin accumulation.

BACKGROUND: Flavanone 3-hydroxylase (F3H), a key enzyme in the flavonoid biosynthetic pathway, plays an important role in the regulation of flavonols and anthocyanidins accumulation. Citrus fruit is a rich source of flavonoids with varied flavonoid compositions among different varieties. To date, the study on F3H is limited in citrus, and its roles in regulating flavonoid accumulation in citrus fruit are still unclear. RESULTS: In this study, we isolated a CitF3H from three different citrus varieties, Satsuma mandarin (Citrus unshiu Marc.), Ponkan mandarin (C. reticulata Blanco) and blood orange 'Moro' (C. sinensis Osbeck). Functional analysis showed that CitF3H encoded a functional flavanone 3-hydroxylase. It catalyzed the hydroxylation of naringenin to yield dihydrokaempferol, which was a precursor of anthocyanins in flavonoid biosynthetic pathway. In the juice sacs, CitF3H was differentially expressed among the three citrus varieties, and its expression level was positively correlated with the accumulation of anthocyanins during the ripening process. In the juice sacs of Satsuma mandarin and Ponkan mandarin the expression of CitF3H kept constant at an extremely low level, and no anthocyanin was accumulated during the ripening process. In contrast, the expression of CitF3H increased rapidly along with the accumulation of anthocyanin in the juice sacs of blood orange 'Moro' during the ripening process. In addition, we found that blue light irradiation was effective to up-regulate the expression of CitF3H and improve anthocyanin accumulation in the juice sacs of blood orange 'Moro' in vitro. CONCLUSION: CitF3H was a key gene regulating anthocyanin accumulation in the juice sacs of citrus fruit. The results presented in this study will contribute to elucidating anthocyanin biosynthesis in citrus fruit, and provide new strategies to improve the nutritional and commercial values of citrus fruit.

Enhanced Corrosion Resistance of Carbon Steel in Hydrochloric Acid Solution by Polyoxometalate-Estertin Derivatives.

The development of acid-resistant and efficient corrosion inhibitors is of great significance for metal protection in many industrial processes. In this work, eight cases of sandwich-type polyoxometalate (POM)-based inorganic-organic hybrids, namely, carboxyethyltin and transition metal (TM) cofunctionalized tungstoantimonates and tungstobismuthates, formulated as Na x K10-x [(SnR)2(TM(H2O)3)2(B-ß-SbW9O33)2]·mH2O and Na y K10-y [(SnR)2(TM(H2O)3)2(B-ß-BiW9O33)2]·nH2O (abbreviated as SbW9-TM-SnR and BiW9-TM-SnR; TM = Mn, Co, Ni, and Zn; m = 18, 24, 24, and 22; n = 30, 25, 20, and 21; SnR = Sn(CH2CH2COO)) are first used as green corrosion inhibitors for 20# carbon steel in 0.5-2.0 M HCl solutions. Weight loss and electrochemical experiments prove that the corrosion inhibition efficiency is all above 81% for these POM-based corrosion inhibitors at 150 mg L-1, and SbW9-Mn-SnR shows the highest efficiency of 96.9% at 150 mg L-1 after immersion in a 0.5 M HCl solution for 10 h. Scanning electron microscopy-energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy analyses show that these POM-based inhibitors form films on the carbon steel and the adsorption mechanism obeys the Langmuir adsorption model. The thermodynamic activation parameters were calculated, proving the occurrence of both chemical and physical adsorptions. The film-forming mechanism was also analyzed. This work provides guidance for synthesizing new lacunary POM-based materials to protect metals from corrosion in HCl pickling.

Exogenous gibberellin induced regreening through the regulation of chlorophyll and carotenoid metabolism in Valencia oranges.

In the present study, we studied the effects of gibberellic acid (GA) on chlorophyll and carotenoid metabolites and related gene expression during the regreening process in Valencia orange fruits (Citrus sinensis Osbeck). During the regreening, fruits treated with GA turned green much faster than those of the control. Compared with untreated fruits, chlorophyll accumulation was induced and the content of carotenoids (ß-cryptoxanthin, all-trans-violaxanthin, and 9-cis-violaxanthin) was decreased by the GA treatment. Chlorophyll and carotenoid contents following GA treatment appeared to be highly regulated at the gene transcription level. Correspondingly, the up-regulation of chlorophyll biosynthesis genes (CitGGDR, CitCHL27, CitPORA, and CitCAO) and down-regulation of degradation genes (CitCLH1, CitSGR, CitPPH, CitPAO, and CitRCCR) led to the increase of chlorophyll contents, and the down-regulation of carotenoid biosynthesis genes (CitPSY, CitPDS, CitZDS, CitLCYb2, and CitHYb) led to the decrease of carotenoid contents. These observations indicated that GA acted as a crucial regulator in the regreening process of citrus fruits.

Characterization of a Caffeic Acid 8-O-Methyltransferase from Citrus and Its Function in Nobiletin Biosynthesis.

Nobiletin (3',4',5,6,7,8-hexamethoxyflavone) is a polymethoxylated flavonoid specifically accumulated in citrus fruit with numerous beneficial effects to human health. In this study, a novel O-methyltransferase (CitOMT2) was isolated from three citrus varieties, Ponkan mandarin (Citrus reticulata Blanco), Nou 6 ("King mandarin" × "Mukaku-kishu"), and Satsuma mandarin (Citrus unshiu Marc.), and its functions were characterized in vitro. The gene expression results showed that CitOMT2 was highly expressed in the two nobiletin abundant varieties of Ponkan mandarin and Nou 6. However, the expression level of CitOMT2 was low in the flavedo of Satsuma mandarin, in which only a small amount of nobiletin was accumulated. Functional analysis suggested that CitOMT2 was a caffeic acid 8-O-methyltransferase, and it catalyzed the O-methylation of 7,8-dihydroxyflavone at 8-OH. As the methylation of flavone at 8-OH was required for nobiletin biosynthesis, the results presented in this study suggested that CitOMT2 was a key gene regulating nobiletin accumulation in citrus fruit.

A POM-based copper-coordination polymer crystal material for phenolic compound degradation by immobilizing horseradish peroxidase.

A new polyoxometalate (POM)-based organic-inorganic hybrid Cu-coordination polymer, namely {((Cu(bipy))2(µ-PhPO3)2Cu(bipy))2H(PCuW11O39)·3H2O}n (denoted as compound 1, bipy = 2,2'-bipyridine, PhPO3 = phenylphosphonate), was self-assembled hydrothermally. Single-crystal X-ray diffraction (SC-XRD) analysis shows that two unique types of 1D chains are present in compound 1, i.e. Cu(II)-organophosphine and organonitrogen complex cation ([((Cu(bipy))2(µ-PhPO3)2Cu(bipy))2]4+) chains and Cu-monosubstituted Keggin-type polyoxoanion ([PCuW11O39]5-) chains, forming a hetero-POM. Crystalline compound 1 as a new enzyme immobilization support exhibited a high horseradish peroxidase (HRP) loading capacity (268 mg g-1). The powder X-ray diffraction (PXRD), FTIR, zeta potential, confocal laser scanning microscopy (CLSM) and circular dichroism (CD) results show that HRP is only immobilized on the surface of compound 1 through simple physical adsorption without a secondary structure change. This POM-immobilized enzyme (HRP/1) was first used for degradation of pollutants in wastewater, and it showed a high degradation efficiency and TOC removal efficiency for phenol, 4-chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP) within 30 min reaction time. Moreover, HRP/1 exhibited better operational and storage stabilities and reusability compared with free HRP. This work suggests that POMs can be used as new supports for enzyme immobilization and POM-immobilized enzymes may be used as a new kind of biocatalyst for degradation of phenolic pollutants.

Exogenous Application of ABA and NAA Alleviates the Delayed Coloring Caused by Puffing Inhibitor in Citrus Fruit.

Combined spraying of gibberellin (GA) and prohydrojasmon (PDJ) was an effective method to reduce peel puffing in Satsuma mandarins. However, in the GA-and-PDJ combined treatment, fruit color development was delayed during the ripening process. In the present study, to improve the coloration of the GA and PDJ-treated fruit, the effects of exogenous application of 1-naphthaleneacetic acid (NAA) and abscisic acid (ABA) on chlorophyll and carotenoid accumulation were investigated. The results showed that both ABA and NAA treatments accelerated the color changes from green to orange in the GA and PDJ-treated fruit during the ripening process. With the NAA and ABA treatments, chlorophylls contents were decreased rapidly, and the contents of ß,ß-xanthophylls were significantly enhanced in the GA and PDJ-treated fruit. In addition, gene expression results showed that the changes of the chlorophyll and carotenoid metabolisms in the NAA and ABA treatments were highly regulated at the transcriptional level. The results presented in this study suggested that the application of NAA and ABA could potentially be used for improving the coloration of the GA and PDJ-treated fruit.

Blue LED light induces regreening in the flavedo of Valencia orange in vitro.

In the present study, the effects of blue LED light on the regreening of citrus fruit were investigated in an in vitro system of Valencia orange flavedos. The results showed that blue LED light irradiation induced regreening in the flavedos. After four-week culture in vitro, the flavedos exhibited obviously green color in the blue LED light treatment, while the flavedos in the control were still in orange color. During the regreening process, the blue LED light treatment induced chlorophyll accumulation, and substantially altered the carotenoid composition in the flavedos. Compared with the control, the content of 9-cis-violaxanthin was decreased, while the contents of lutein, ß-carotene, and all-trans-violaxanthin were increased by blue LED light. In addition, gene expression results showed that the up-regulation of CitLCYe and down-regulation of CitLCYb2 by blue LED light led to a shift from ß,ß-branch to ß,ε-branch of the carotenoid biosynthetic pathway.

Expression and functional analysis of the nobiletin biosynthesis-related gene CitOMT in citrus fruit.

Nobiletin, a polymethoxy flavone (PMF), is specific to citrus and has been reported to exhibit important health-supporting properties. Nobiletin has six methoxy groups at the 3',4',5,6,7,8-positions, which are catalyzed by O-methyltransferases (OMTs). To date, researches on OMTs in citrus fruit are still limited. In the present study, a novel OMT gene (CitOMT) was isolated from two citrus varieties Satsuma mandarin (Citrus unshiu Marc.) and Ponkan mandarin (Citrus reticulata Blanco), and its function was characterized in vitro. The results showed that the expression of CitOMT in the flavedo of Ponkan mandarin was much higher than that of Satsuma mandarin during maturation, which was consistent with the higher accumulation of nobiletin in Ponkan mandarin. In addition, functional analysis showed that the recombinant protein of CitOMT had methylation activity to transfer a methyl group to 3'-hydroxy group of flavones in vitro. Because methylation at the 3'-position of flavones is vital for the nobiletin biosynthesis, CitOMT may be a key gene responsible for nobiletin biosynthesis in citrus fruit. The results presented in this study will provide new strategies to enhance nobiletin accumulation and improve the nutritional qualities of citrus fruit.

Two new estertin modified tungstosilicates: synthesis, catalytic activity and photoelectrochemical property.

Two new tungstosilicates (C(NH2)3)5KNa2H3[Sn(CH2CH2COOCH3)Co(H2O)2Si2W19O69]·10H2O (Si2W19-Co-SnRCOOCH3) and (C(NH2)3)5KNa2H3[Sn(CH2CH2COOCH3)Mn(H2O)2Si2W19O69]·13H2O (Si2W19-Mn-SnRCOOCH3) modified by organometal (OM) and transition metal (TM) ions were obtained, and they were self-assembled from mono-TM-containing (TM = Co, Mn) γ-[SiW10O35]6- (γ-SiW10)-based dimeric tungstosilicate and estertin Cl3SnCH2CH2COOCH3 in an acetate buffer solution, respectively. Their structures were determined with a series of physico-chemical and spectroscopic methods including X-ray crystallography, XRPD, etc. The estertin functional position in the tungstosilicate skeleton was analyzed by theoretical calculations using density functional theory (DFT). These two compounds have good catalytic activity for the oxidation of cyclohexanol to cyclohexanone. Meanwhile, they were composited with TiO2 using a facial layer-by-layer (LBL) method. The assembled composite films {Si2W19-TM-SnRCOOCH3/TiO2}n (TM = Co, Mn; n is the bilayer number, n = 1-6) exhibit efficient photoelectrocatalytic activity for the oxidation of methanol under irradiation of 100 mW cm-2 using a Xe lamp as a light source. And the {Si2W19-Co-SnRCOOCH3/TiO2}4 film produces the highest photocurrent among the composite films studied in this work. Combining the dark current measurement, surface photovoltage spectroscopy (SPV) and electrochemical impedance spectroscopy (EIS), the enhanced photoelectrocatalytic activity of {Si2W19-Co-SnRCOOCH3/TiO2}4 composite film for the oxidation of methanol is attributed to the suppressed electron-hole recombination, increased carrier separation efficiency and interfacial charge transfer.

Carboxyethyltin and transition metal co-functionalized tungstoantimonates composited with polypyrrole for enhanced electrocatalytic methanol oxidation.

Carboxyethyltin and first-row transition metals (TMs) were firstly introduced into trivacant Keggin-type tungstoantimonate in an aqueous solution, leading to the formation of four crystalline organic-inorganic hybrid sandwich-type polyoxometalates (POMs), formulated as Na10-x-yKyHx[((TM)(H2O)3)2(Sn(CH2)2COO)2(SbW9O33)2]·nH2O (SbW9-TM-SnR, TM = Mn, Co, Ni, Zn; x = 1, 1, 0, 0; y = 0, 5, 5, 2; n = 18, 24, 24, 22, respectively). SbW9-TM-SnR exhibit high catalytic ability for the oxidation of cyclohexanol. Meanwhile, SbW9-TM-SnR were composited with polypyrrole (PPy) through an electropolymerization process, forming PPy-SbW9-TM-SnR, on which platinum (Pt) was further electro-deposited to prepare PPy-SbW9-TM-SnR/Pt for electrocatalytic methanol (CH3OH) oxidation in acid solution. The composition and morphology of PPy-SbW9-TM-SnR/Pt were determined by IR, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The electrochemical experimental results show that SbW9-TM-SnR and PPy obviously enhance the electrocatalytic and anti-intoxication abilities of Pt, and the highest peak current density of 0.87 mA cm-2, corresponding to 1.85 and 1.43 times higher than those of pure Pt and PPy/Pt electrodes respectively, is acquired for the PPy-SbW9-Ni-SnR/Pt composite electrode. These findings may enlarge the application of PPy and POMs in the electrocatalytic field.

Three new Strandberg-type phenylphosphomolybdate supports for immobilizing horseradish peroxidase and their catalytic oxidation performances.

Three organic-inorganic hybrids containing Strandberg-type phenylphosphomolybdate anion [(C6H5PO3)2Mo5O15]4- with phenylphosphonate (PhP) centers, transition metal (TM) ions and 2,2'-biimidazole (H2biim) ligand, formulated as [(TM(H2biim)2)2(C6H5PO3)2Mo5O15]·H2O (TM = Co and Cu, abbreviated as Co-(PhP)2Mo5 and Cu-(PhP)2Mo5, respectively) and ([Ni(H2biim)3])2[(C6H5PO3)2Mo5O15]·2H2O (abbreviated as Ni-(PhP)2Mo5), were self-assembled by simple hydrothermal methods and were systematically characterized through single-crystal X-ray diffraction and other physicochemical and spectroscopic methods, which demonstrated that TM-H2biim complexes were firstly introduced into Strandberg-type organophosphomolybdate skeletons. Selecting the oxidation of cyclohexanol to cyclohexanone as a model reaction, using H2O2 as an oxidant, the catalytic oxidation activities of the Strandberg-type compounds were firstly evaluated. More importantly, these TM-(PhP)2Mo5 (TM = Co, Cu, Ni) compounds were employed to immobilize horseradish peroxidase (HRP), and showed high adsorption capacities for HRP. Laser scanning confocal microscope images showed that HRP adsorbed on the surfaces of the TM-(PhP)2Mo5 supports. Application of immobilized enzyme HRP/TM-(PhP)2Mo5 for the detection of H2O2 is also discussed.

Accumulation of carotenoids in a novel citrus cultivar 'Seinannohikari' during the fruit maturation.

In the present study, carotenoid metabolism was investigated in the fruits of a novel citrus cultivar, 'Seinannohikari' (Citrus spp.). During the maturation, ß,ß-xanthophylls were accumulated rapidly with ß-cryptoxanthin being the dominant carotenoid compound in the flavedo and juice sacs of 'Seinannohikari'. In the juice sacs of mature fruits, 'Seinannohikari' accumulated high amount of carotenoids, especially ß-cryptoxanthin. The content of ß-cryptoxanthin in the juice sacs of 'Seinannohikari' was approximately 2.5 times of that in 'Miyagawa-wase' (Citrus unshiu), which is one of its parental cultivars, at the mature stage. Gene expression results showed that the massive accumulation of ß-cryptoxanthin might be attributed to the higher expression of carotenoid biosynthetic genes (CitPSY, CitPDS, CitZDS, CitLCYb2, CitHYb, and CitZEP), and lower expression of carotenoid catabolic genes (CitNCED2 and CitNCED3) in the juice sacs of 'Seinannohikari'.

Two New Preyssler-Type Polyoxometalate-Based Coordination Polymers and Their Application in Horseradish Peroxidase Immobilization.

Enzyme immobilization is of increasing importance for biocatalysis, for which good supports are critical. Herein, two new Preyssler-type polyoxometalate (POM)-based coordination polymers, namely, {[Cu(H2 biim)2 ][{Cu(H2 biim)2 (µ-H2 O)}2 Cu(H2 biim)(H2 O)2 ]H[({Cu(H2 biim)(H2 O)2 }0.5 )2 ((µ-C3 HN2 Cl2 ){Cu(H2 biim)}2 ){Z(H2 O)P5 W30 O110 }]⋅x H2 O}n (1: Z=Na, x=9; 2: Z=Ag, x=10; H2 biim=2,2'-biimidazole) were designed and synthesized. Compounds 1 and 2 exhibit the same skeletons, which contain multiple CuII complex fragments and penta-supported {ZP5 W30 } (Z=Na, Ag) clusters. They were first employed to immobilize horseradish peroxidase (HRP). Results show that compounds 1 and 2 are good supports for HRP immobilization, and exhibit higher enzyme loading, lower loading times, and excellent reusability. The immobilized HRP (HRP/1 or HRP/2) was further applied to detect H2 O2 , and good sensitivity, wide linear range, low detection limit, and fast response were achieved. This work shows that POM-based hybrid materials are a new kind of promising support for enzyme immobilization.

Biomolecule-mediated hydrothermal synthesis of polyoxoniobate-CdS nanohybrids with enhanced photocatalytic performance for hydrogen production and RhB degradation.

Using a biomolecule of l-cystine as the sulfur source and coordinating agent, polyoxoniobate-CdS nanohybrids were successfully synthesized under mild hydrothermal conditions. The adsorption of ammonium group (-NH2) in l-cystine molecular structure on the surface of CdS renders the amine-anchored CdS positively charged, which readily combines with the negatively charged polyoxoniobate clusters in terms of the electrostatic interaction. The as-obtained polyoxoniobate-CdS nanohybrids exhibit much superior activity for H2 evolution and RhB degradation under visible light as compared to the unhybridized CdS and polyoxoniobate. After co-loading Nb6 and NiS as cocatalyst, the H2-evolution activity of the nanohybrids is further increased up to 39 times as high as that of naked CdS, which can be attributed to an enhanced electron-transfer by adopting polyoxoniobate as electron-acceptor to retard the electron-hole recombination. The work may open an avenue for the green synthesis of cost-effective POMs-CdS nanohybrid photocatalysts for solar energy applications.

Identification and quantitative analysis of ß-cryptoxanthin and ß-citraurin esters in Satsuma mandarin fruit during the ripening process.

In this study, to investigate the xanthophyll accumulation in citrus fruits, the major fatty acid esters of ß-cryptoxanthin and ß-citraurin were identified, and changes in their contents were investigated in two Satsuma mandarin varieties, 'Miyagawa-wase' and 'Yamashitabeni-wase', during the ripening process. The results showed that ß-cryptoxanthin and ß-citraurin were mainly esterified with lauric acid, myristic acid, and palmitic acid in citrus fruits. During the ripening process, ß-cryptoxanthin laurate, myristate, and palmitate were accumulated gradually in the flavedos and juice sacs of the two varieties. In the flavedo of 'Yamashitabeni-wase', ß-citraurin laurate, myristate, and palmitate were specifically accumulated, and their contents increased rapidly with a peak in November. In addition, functional analyses showed that CitCCD1 and CitCCD4 efficiently cleaved the free ß-cryptoxanthin, but not the ß-cryptoxanthin esters in vitro. The substrate specificity of CitCCDs towards free ß-cryptoxanthin indicated that ß-cryptoxanthin esters might be more stable than free ß-cryptoxanthin in citrus fruits.

Expression and functional analysis of citrus carotene hydroxylases: unravelling the xanthophyll biosynthesis in citrus fruits.

BACKGROUND: Xanthophylls are oxygenated carotenoids and fulfill critical roles in plant growth and development. In plants, two different types of carotene hydroxylases, non-heme di-iron and heme-containing cytochrome P450, were reported to be involved in the biosynthesis of xanthophyll. Citrus fruits accumulate a high amount of xanthophylls, especially ß,ß-xanthophylls. To date, however, the roles of carotene hydroxylases in regulating xanthophyll content and composition have not been elucidated. RESULTS: In the present study, the roles of four carotene hydroxylase genes (CitHYb, CitCYP97A, CitCYP97B, and CitCYP97C) in the biosynthesis of xanthophyll in citrus fruits were investigated. Phylogenetic analysis showed that the four citrus carotene hydroxylases presented in four distinct clusters which have been identified in higher plants. CitHYb was a non-heme di-iron carotene hydroxylase, while CitCYP97A, CitCYP97B, and CitCYP97C were heme-containing cytochrome P450-type carotene hydroxylases. Gene expression results showed that the expression of CitHYb increased in the flavedo and juice sacs during the ripening process, which was well consistent with the accumulation of ß,ß-xanthophyll in citrus fruits. The expression of CitCYP97A and CitCYP97C increased with a peak in November, which might lead to an increase of lutein in the juice sacs during the ripening process. The expression level of CitCYP97B was much lower than that of CitHYb, CitCYP97A, and CitCYP97C in the juice sacs during the ripening process. Functional analysis showed that the CitHYb was able to catalyze the hydroxylation of the ß-rings of ß-carotene and α-carotene in Escherichia coli BL21 (DE3) cells. Meanwhile, when CitHYb was co-expressed with CitCYP97C, α-carotene was hydroxylated on the ß-ring and ε-ring sequentially to produce lutein. CONCLUSIONS: CitHYb was a key gene for ß,ß-xanthophyll biosynthesis in citrus fruits. CitCYP97C functioned as an ε-ring hydroxylase to produce lutein using zeinoxanthin as a substrate. The results will contribute to elucidating xanthophyll biosynthesis in citrus fruits, and provide new strategies to improve the nutritional and commercial qualities of citrus fruits.

Two New Armtype Polyoxometalates Grafted on Titanium Dioxide Films: Towards Enhanced Photoelectrochemical Performance.

Two new carboxyethyltin-functionalized polyoxometalates (POMs) were successfully obtained and confirmed with physicochemical and spectroscopic methods including X-ray crystallography. The lowest unoccupied molecular orbitals of both compounds are higher in energy than that of TiO2 , and the optical band gaps of these compounds are smaller than that of TiO2 . Grafting them onto a TiO2 film created two kinds of novel photoanode materials that showed significantly enhanced photovoltaic and photocurrent responses, as well as improved photoelectrooxidation activities for methanol relative to that shown by a single TiO2 film. Further, P2 W15 -Co-SnR produced the largest photocurrent by exploring the photoelectric activities of a series of carboxyethyltin POM derivatives. This work provides new insight into the photoelectrochemical functionalization of POM-based organic-inorganic hybrids.

Controllable assembly, characterization and catalytic properties of a new Strandberg-type organophosphotungstate.

Using phenylphosphonic acid, simple tungstate and copper(ii) compounds as starting materials, an organic-inorganic hybrid Strandberg-type organophosphotungstate, {[(Cu(H2O)(µ-bipy))2(C6H5PO3)2W5O15]}n (bipy = 4,4'-bipyridyl) (1), was assembled successfully under hydrothermal conditions and characterized by physico-chemical and spectroscopic methods. Compound 1 represents the first example of a transition metal complex modified organophosphotungstate cluster. In the crystal structure of compound 1, the polymeric 1-D {Cu-bipy}n chains are interconnected by [(C6H5PO3)2W5O15](4-) (abbreviated as {(C6H5P)2W5}) units into a 3-D framework. A hollow Keggin isopolytungstate [H2W12O40](6-) ({W12})-Cu(ii) coordination polymer, {[Cu(bipy)2((µ-bipy)Cu(bipy))2(H2W12O40)]·12H2O}n (2), was obtained at different molar ratios of the starting materials and pH. The two Cu(ii) coordination polymers exhibit good acid-catalytic activity for the synthesis of cyclohexanone ethylene ketal. Their fluorescence properties were studied.

Effect of blue LED light intensity on carotenoid accumulation in citrus juice sacs.

In the present study, the effects of blue LED light intensity on carotenoid accumulation and expression of genes related to carotenoid biosynthesis were investigated in the juice sacs of Satsuma mandarin (Citrus unshiu Marc.) and Valencia orange (Citrus sinensis Osbeck) in vitro. The results showed that 100 µmol m(-2)s(-1) blue LED light (100B) was effective for increasing carotenoid content, especially ß-cryptoxanthin, in Satsuma mandarin after cultured in vitro for four weeks. In Valencia orange, in contrast, 50 µmol m(-2)s(-1) blue LED light (50B) treatment was effective for inducing carotenoid accumulation through increasing the contents of two major carotenoids, all-trans-violaxanthin and 9-cis-violaxanthin. In addition, gene expression results showed that the simultaneous increases in the expression of genes (CitPSY, CitPDS, CitZDS, CitLCYb2, and CitHYb) involved in producing ß,ß-xanthophylls were well consistent with the accumulation of ß-cryptoxanthin in Satsuma mandarin under 100B, and violaxanthin in Valencia orange under 50B. The results presented herein contribute to further elucidating the regulatory mechanism of carotenoid accumulation by blue LED light.