Effects of Three Essential Oil Fumigation Treatments on the Postharvest Control of Botrytis cinerea and Their Efficacy as Preservatives of Cherry Tomatoes.

Cherry tomatoes (Solanum lycopersicum) are becoming increasingly popular due to their nutrition and delicious flavor. However, cherry tomatoes are highly perishable and susceptible to various pathogenic microorganisms after harvest, such as Botrytis cinerea. In the pretest experiment, we screened out three kinds of plant essential oils (EOs) (Torreya grandis oil, Eriobotrya japonica oil, and Citrus medica oil) that have strong fungicidal activity on B. cinerea from cherry tomatoes. To further evaluate the postharvest preservation application prospect of these three oils for cherry tomatoes, the oils were extracted from different parts of three plants by hydrodistillation, and their chemical constituents were analyzed by gas chromatography-mass spectrometry. The main representative components of T. grandis oil, E. japonica oil, and C. medica oil were δ-cadinene (11.76%), transnerolidol (9.70%), and 5,7-dimethoxycoumarin (23.22%), respectively. These three EOs effectively inhibited the mycelial growth of B. cinerea in vitro, with EC50 values of 81.672, 144.046, and 221.500 µl/liter, respectively. Compared with the blank control and other oil treatments, the T. grandis oil (at a concentration of 200 µl/liter) fumigation treatment was more effective at inhibiting the growth rate of the pathogen. In addition, the phenolic content and phenylalanine ammonia lyase, ß-1,3-glucanase, chitinase, and peroxidase activities of tomatoes significantly increased on the seventh day due to the T. grandis oil treatment. The present study shows that these three oils with high extraction rates have preservation potential for cherry tomatoes. Among these three EOs, T. grandis oil can be used to further develop preservative products as a fumigant.

Two single mutations in carboxylesterase 001C improve fenvalerate hydrolase activity in Helicoverpa armigera.

Carboxylesterases (CarEs) usually play critical roles in the detoxification of toxic chemicals and therefore may be involved in insecticide resistance in agricultural pests. Previous work has shown that CarE 001C from Helicoverpa armigera was able to metabolize the isomers of cypermethrin and fenvalerate. In this study, seven mutants of CarE 001C with single amino acid substitution were produced and expressed in the Escherichia coli. Enzyme kinetic analysis indicated that all seven mutations dramatically reduced enzymatic activities toward the generic substrate α-naphthyl acetate, but in vitro metabolism assay showed that two of the mutations, H423I and R322L, significantly improved hydrolase activities toward fenvalerate, with their recorded specific activities being 3.5 and 5.1 nM·s-1·mg -1 proteins, respectively. Further, thermostability assay showed that the stability of one mutant enzyme was enhanced. This study will help us better understand the potential of CarEs in insecticide detoxification and resistance in H. armigera.

Effects of RNAi-mediated plasma membrane calcium transporting ATPase and inositol 1,4,5-trisphosphate receptor gene silencing on the susceptibility of Mythimna separata to wilforine.

Wilforine, a compound of sesquiterpene alkaloids isolated from Tripterygium wilfordii, exhibits excellent insecticidal activity against Mythimna separata. In order to clarify the action mechanism of wilforine, the plasma membrane calcium transporting ATPase (PMCA) and inositol 1,4,5-trisphosphate receptor (IP3R) from M. separata were studied. Results showed that the open reading frame of MsIP3R and MsPMCA were 8118 bp and 3438 bp in length, as well as encoded 2706 and 1146 amino acids, respectively. Multiple sequence alignment and phylogenetic analysis revealed that the MsIP3R and MsPMCA had high homology with the IP3R and PMCA of other insects, but had low similarity with those of mammals, which means the IP3R and PMCA have potential to be the novel targets of insecticides with high selectivity between mammals and insects. Both MsIP3R and MsPMCA genes existed throughout the life cycle of M. separata, and were all predominantly expressed in somatic muscle of fifth-instar larvae and the adults. The susceptibilities of PMCA-silenced M. separata to wilforine were significantly lower than that of the normal M. separata, which illustrates that PMCA could be one of the targets of wilforine. However, the susceptibilities of IP3R-silenced M. separata to wilforine did not change significantly compared with the susceptibilities of normal M. separata, which shows that wilforine may not interact with the IP3R protein. These findings provide clues for elucidating the insecticidal mechanism of wilforine.

Enhanced hydrolysis of ß-cypermethrin caused by deletions in the glycin-rich region of carboxylesterase 001G from Helicoverpa armigera.

BACKGROUND: Carboxylesterase (CarE) is a major class of enzyme involved in the detoxification of toxic xenobiotics in various insect species. Previous work has shown that the carboxylesterase gene CarE001G found in Helicoverpa armigera is more active and can metabolize synthesized pyrethroids, such as ß-cypermethrin, one of the commonly used commercial insecticides for lepidopteran pest control. In addition, CarE001G is very special as it has a very specific glycine-rich region located adjacent to its C-terminal. But whether mutations in this unique sequence can change the biochemistry and function of CarE001G are unknown. RESULTS: In this study, four variants of CarE001G with different deletions in the glycine-rich region were obtained and functionally expressed in Escherichia coli. The recombinant proteins were purified and confirmed by Western blot and mass spectrometry analyses. These mutant enzymes showed high catalytic efficiency toward the model substrate α-naphthyl acetate. Inhibition study showed that ß-cypermethrin had relatively strong inhibition on CarE activities. In vitro metabolism assay showed that the mutant enzymes significantly enhanced their metabolic activities toward ß-cypermethrin with specific activities between 4.0 and 5.6 nmol L-1 min-1 mg-1 protein. Molecular docking analyses consistently demonstrated that deletion mutations in the glycine-rich region may facilitate the anchoring of the ß-cypermethrin molecule in the active binding pocket of the mutant enzymes. CONCLUSION: The data show that deletion mutations can cause qualitative change in the capacity of CarEs in the detoxification of ß-cypermethrin. This indicates that deletion mutations in the glycine-rich region may have the potential to cause synthesized pyrethroid (SP) resistance in H. armigera in the future. © 2020 Society of Chemical Industry.

Functional Characterization of Two Carboxylesterase Genes Involved in Pyrethroid Detoxification in Helicoverpa armigera.

Insect carboxylesterases are major enzymes involved in metabolism of xenobiotics including insecticides. Two carboxylesterase genes, CarE001A and CarE001H, were cloned from the destructive agricultural pest Helicoverpa armigera. Quantitative real-time polymerase chain reaction showed that CarE001A and CarE001H were predominantly expressed in fat body and midgut, respectively; developmental expression analyses found that the expression levels of both CarEs were significantly higher in fifth-instar larvae than in other life stages. Recombinant CarE001A and CarE001H expressed in the Escherichia coli exhibited high enzymatic activity toward α-naphthyl acetate. Inhibition assays showed that organophosphates had strong inhibition on CarEs activity compared to pyrethroids. Metabolism assays indicated that CarE001A and CarE001H were able to metabolize ß-cypermethrin and λ-cyhalothrin. Homology modeling and molecular docking analyses demonstrated that ß-cypermethrin could fit nicely into the active pocket of both carboxylesterases. These results suggested that CarE001A and CarE001H could play important roles in the detoxification of pyrehtroids in H. armigera.

Efficacy of binary combinations between methyl salicylate and carvacrol against thrips Anaphothrips obscurus: laboratory and field trials.

BACKGROUND: Thrips Anaphothrips obscurus are one of the cosmopolitan major pests feeding on cereals and other grasses. In order to develop alternatives of chemical insecticides for thrips control, based on fumigant activity screening and evaluation of 22 essential oil (EO) compounds against the thrips, the binary interactions of methyl salicylate and carvacrol (MS-C) with high fumigant toxicity were studied systematically by bioassay and field trials. RESULTS: The bioassay results showed that six in 22 EO compounds had high fumigant toxicity against both the second-instar nymphs and adults of A. obscurus, including methyl salicylate, carvacrol, thymol, trans-cinnamaldehyde, diallyl trisulfide, and L-perillaldehyde. Furthermore, the combination of methyl salicylate mixed with carvacrol at a volume ratio of 5:5 exhibited the most significant synergism against A. obscurus, with a poison ratio value of 1.32 and a co-toxicity coefficient of 151.15. The optimal formulation of microemulsion (ME) was composed of 5% methyl salicylate, 5% carvacrol, 46% adjuvant and 44% deionized water. The result of dynamic light scattering and stability showed that MS-C 10% ME was a transparent, single-phase and homogeneous liquid system. Field trials indicated that the ME displayed a significant control efficacy of about 89.17% on thrips in peppers, and 82.59% in broad bean on the seventh day post application with a dosage of 600.0 g A.I hm-2 , respectively. CONCLUSION: The binary combination of MS-C possesses strikingly synergistic action against thrips A. obscurus, and the MS-C 10% ME has the potential to be developed as a botanical pesticide product for thrips control. © 2019 Society of Chemical Industry.

Europium(III) functionalized 3D covalent organic framework for quinones adsorption and sensing investigation.

Chemical functionalization is essential for tuning the physical-chemical characters and broadening the potential applications of covalent organic frameworks (COFs). Based on the multistep postsynthetic modification strategy, Eu (III)-functionalized 3D COF (Eu-3D-COF) was prepared by grafting of Eu (III) onto the carboxyl-funtionalized 3D-COF (COOH-3D-COF). With micropores dominated microspheres structure, Eu-3D-COF exhibited superior adsorption affinity to multi-rings contained quinones based on the π-π interaction, coordination and hydrogen-bonding interactions, especially to 9,10-phenanthrenequinone (PQ) whose adjacent carbonyl oxygens resulting preferable synergistic chelation interaction with Eu(III) was responsible for the maximum adsorption capacity, which was confirmed by instrumental characterizations. The adsorptivity of Eu-3D-COF was apparently improved in comparison with COOH-3D-COF. More importantly, grafting of Eu(III) turned on the fluorescence of the COF, making Eu-3D-COF also a superior chemosensor for sensing application. Its fluorescent can be selectively quenched by quinones, especially by PQ based on the PQ-Eu and PQ-COF interactions co-dominated energy transfer. Therefore, both as an adsorbent and a chemosensor, the multi-functional COF was explored for quinones adsorption and sensing detection investigation in detail. Eu-3D-COF has promising application potentials for hazardous quinones adsorption and sensing detection, which also opens new perspectives for inorganic-organic 3D-COF construction and multi-functional applications.

Identification and biochemical characterization of carboxylesterase 001G associated with insecticide detoxification in Helicoverpa armigera.

Carboxylesterases (CarEs) are a major class of detoxification enzymes involved in insecticide resistance in various insect species. In this study, a novel CarE 001G was isolated from the cotton bollworm Helicoverpa armigera, one of the most destructive agricultural insect pests. The open reading frame of 001G has 2244 nucleotides and putatively encodes 747 amino acid residues. The deduced CarE possessed the highly conserved catalytic triads(Ser-Glu-His) and pentapeptide motifs (Gly-X-Ser-X-Gly), suggesting 001G is biologically active. The truncated 001G was successfully expressed in Escherichia coli, and the recombinant proteins were purified and tested. The enzyme kinetic assay showed the purified proteins could catalyze two model substrates, α-naphthyl acetate and ß-naphthyl acetate, with a kcat of 8.8 and 2.3 s-1, a Km of 9.6 and 16.2 µM, respectively. The inhibition study with pyrethroid, organophosphate and neonicotinoid insecticides showed different inhibition profile against the purified CarE. The HPLC assay demonstrated that the purified proteins were able to metabolize ß-cypermethrin, λ-cyhalothrin and fenvalerate insecticides, exhibiting respective specific activities of 1.7, 1.4 and 0.5 nM/min/mg protein. However, the purified proteins were not able to metabolize the chlorpyrifos, parathion-methyl, paraoxon-ethyl and imidacloprid. The modeling and docking analyses consistently demonstrated that the pyrethroid molecule fits snugly into the catalytic pocket of the CarE 001G. Collectively, our results suggest that 001G may play a role in pyrethroids detoxification in H. armigera.

Validation of suitable reference genes for quantitative gene expression analysis in Tripterygium wilfordii.

Validation of suitable reference genes is critical in quantitative real-time polymerase chain reaction (qRT-PCR) analysis. Suitable and reliable reference genes for the normalization of gene expression data are characterized by high gene expression stability across tissues and different experimental conditions. This study evaluated the gene expression stability of ten reference genes commonly used in Arabidopsis thaliana for their suitability in qRT-PCR analysis in Tripterygium wilfordii Hook.f. The orthologous sequences of these ten candidate genes were identified from T. wilfordii transcriptomic data (Project No. SRX472292). Five algorithms including GeNorm, NormFinder, BestKeeper, ΔCt, and RefFinder were used to assess the gene expression stability of these putative reference genes in different plant tissues and different stress conditions. The results identified ACTINT7 and TBP as the most suitable reference genes across all samples. The gene expressions of TwHMGR (3-hydroxy-3-methylglutaryl coenzyme A reductase, KU246037.1) and of TwDXR (1-deoxy-D-xylulose-5-phosphate reductoisomerase, KJ174341.1) were investigated to validate the suitability of the reference genes. The validation analysis confirmed the suitability of ACTINT7 and TBP as the best reference genes for elucidating secondary metabolite biosynthesis pathway in T. wilfordii. In summary, this study identified the most suitable and reliable reference genes for future qRT-PCR- based studies in T. wilfordii.

New Cytotoxic Secondary Metabolites from Marine Bryozoan Cryptosula pallasiana.

A new sterol, (23R)-methoxycholest-5,24-dien-3ß-ol (1), two new ceramides, (2S,3R,4E,8E)-2-(tetradecanoylamino)-4,8-octadecadien-l,3-diol (6) and (2S,3R,2'R,4E,8E)-2-(tetradecanoylamino)-4,8-octadecadien-l,3,2'-triol (7), together with three known sterols (2-4), a lactone (5) and two ceramides (8,9), were isolated from the marine bryozoan Cryptosula pallasiana, collected at Huang Island of China. The structures of the new compounds were elucidated by extensive spectroscopic analyses, chemical methods and quantum electronic circular dichroism (ECD) calculations. Among the isolated compounds, sterol 1 possessed a rare side chain with a methoxy group at C-23, and a double bond between C-24 and C-25. Ceramides 6 and 7 possessed 14 carbons in their long-chain fatty acid base (FAB), which were different from the normal ceramides with 16 carbons in the FAB. Moreover, compounds 5 and 8 were isolated for the first time from marine bryozoans. Compounds 1-9 were evaluated for their cytotoxicity against human tumor cell lines HL-60, Hep-G2 and SGC-7901. The results showed that lactone 5 appears to have strong cytotoxicity against the test tumor cell lines, with IC50 values from 4.12 µM to 7.32 µM, and sterol 1 displayed moderate cytotoxicity with IC50 values between 12.34 µM and 18.37 µM, while ceramides 6-9 showed weak cytotoxicity with IC50 ranging from 21.13 µM to 58.15 µM.

Differential expressed analysis of Tripterygium wilfordii unigenes involved in terpenoid backbone biosynthesis.

Tripterygium wilfordii Hook. f. is the traditional medicinal plants in China. Triptolide, wilforgine, and wilforine are the bioactive compounds in T. wilfordii. In this study, the contents of three metabolites and transcription levels of 21 genes involved in three metabolites biosynthesis in T. wilfordii were examined using high-performance liquid chromatography and reverse transcription PCR after application of methyl jasmonate (MeJA) on hairy roots in time course experiment (3-24 h). The results indicated that application of MeJA inhibited triptolide accumulation and promoted wilforgine and wilforine metabolites biosynthesis. In hairy roots, wilforgine content reached 693.36 µg/g at 6 h after adding MeJA, which was 2.23-fold higher than control. The accumulation of triptolide and wilforine in hairy roots increased the maximum at 9 h, which was 1.3- and 1.6-folds more than the control. Most of the triptolide secretes into the medium, but wilforgine and wilforine cannot secrete into the medium. The expression levels of unigenes which involved terpenoid backbone biosynthesis exist the correlation with marker metabolites (triptolide, wilforgine and wilforine) after induction by MeJA, and can be then used to infer flux bottlenecks in T. wilfordii secondary metabolites accumulation. These results showed that these genes may have potential applications in the metabolic engineering of T. wilfordii metabolites production.

Molecular cloning and expression analysis of cytochrome c oxidase subunit II from Sitophilus zeamais.

Cytochrome c oxidase subunit II (COX II) containing a dual core CuA active site is one of the core subunits of mitochondrial Cytochrome c oxidase (Cco), which plays a significant role in the physiological process. In this report, the full-length cDNA of COXII gene was cloned from Sitophilus zeamais, which had an open reading frame (ORF) of 684 bp encoding 227 amino acids residues. The predicted COXII protein had a molecular mass of 26.2 kDa with pI value of 6.37. multiple sequence alignment and phylogenetic analysis indicated that Sitophilus zeamais COXII had high sequence identity with the COXII of other insect species. The gene was subcloned into the expression vector pET-32a, and induced by isopropyl ß-d-thiogalactopyranoside (IPTG) in E. coli Transetta (DE3) expression system. Finally the recombinant COXII with 6-His tag was purified using affinity chromatography with Ni(2+)-NTA agarose. Western Blotting (WB) showed the recombinant protein was about 44 kD, and the concentration of fusion protein was 50 µg/mL. UV-spectrophotometer and infrared spectrometer analysis showed that recombinant COXII could catalyze the oxidation of substrate Cytochrome C (Cyt c), and influenced by allyl isothiocyanate (AITC). By using molecular docking method, It was found that a sulfur atom of AITC structure could form a length of 2.9 Å hydrogen bond with Leu-31. These results suggested that tag-free COXII was functional and one of the action sites of AITC, which will be helpful to carry out a point mutation in binding sites for the future research.

Design, synthesis and fungicidal activities of some novel pyrazole derivatives.

In order to discover new compounds with good fungicidal activities, 32 pyrazole derivatives were designed and synthesized. The structures of the target compounds were confirmed by 1H-NMR, 13C-NMR, and high-resolution electrospray ionization mass spectrometry (HR-ESI-MS), and their fungicidal activities against Botrytis cinerea, Rhizoctonia solani Kuhn, Valsa mali Miyabe et Yamada, Thanatephorus cucumeris (Frank) Donk, Fusarium oxysporum (S-chl) f.sp. cucumerinum Owen, and Fusarium graminearum Schw were tested. The bioassay results indicated that most of the derivatives exhibited considerable antifungal activities, especially compound 26 containing a p-trifluoromethyl- phenyl moiety showed the highest activity, with EC50 values of 2.432, 2.182, 1.787, 1.638, 6.986, and 6.043 µg/mL against B. cinerea, R. solani, V. mali, T. cucumeris, F. oxysporum, and F. graminearum, respectively. Moreover, the activities of compounds such as compounds 27-32 were enhanced by introducing isothiocyanate and carboxamide moieties to the 5-position of the pyrazole ring.

Fumigant activity of eleven essential oil compounds and their selected binary mixtures against Culex pipiens pallens (Diptera: Culicidae).

To seek natural products for the development of environment friendly mosquito control agents, fumigant activity of eleven essential oil compounds and the joint action of the active compounds were evaluated against Culex pipiens pallens adults. Fumigant bioassay demonstrated that carvacrol exhibited the highest fumigant activity followed by thymol and l-perillaldehyde, with LC50 values of 0.26, 0.28, and 0.34 mg/L air, respectively. Among the binary mixtures of four compounds with preferable performance, only the binary mixture of carvacrol and thymol (1:1, w/w) displayed a synergistic effect with the co-toxicity coefficient (CTC) value of 174.1 and LC50 value of 0.16 mg/L air. Furthermore, the actual efficacy of the binary mixture at 300 mg/mat (KT50 = 7.9, 15.8, and 22.0 min after 0, 2, and 4 h of preliminary heating, respectively) was comparable with that of d-allethrin at 30 mg/mat (KT50 = 8.7, 17.9, and 21.2 min after 0, 2, and 4 h of preliminary heating, respectively) tested in vaporizing mats by the glass chamber method (70 × 70 × 70 cm). These results revealed that carvacrol, thymol, and their binary mixture have potential for the development of natural fumigants for adult mosquito control.

Two new steroids from sclerotia of the fungus Omphalia lapidescens.

Two new steroids, leiwansterols A and B, along with three known ones (3-5), were isolated from the sclerotia of the fungus Omphalia lapidescen. Their structures were elucidated on the basis of spectral data. The isolated compounds showed weak anti-tobacco mosaic virus activity.

Synthesis and antifungal activity of carabrone derivatives.

Nine derivatives 6-14 of carabrone (1) were synthesized and tested in vitro against Colletotrichum lagenarium Ell et Halst using the spore germination method. Among all of the derivatives, compounds 6-8 and 12 showed more potent antifungal activity than 1. Structure-activity relationships (SAR) demonstrated that the γ-lactone was necessary for the antifungal activity of 1, and the substituents on the C-4 position of 1 could significantly affect the antifungal activity.

Development of an enzyme-linked immunosorbent assay for toosendanin.

Enzyme-linked immunosorbent assays (ELISAs) were developed by using polyclonal antibody for toosendanin (TSN), a biopesticide from Melai toosendan Sieb. et Zucc. Their application in the determination of this analyte in spiked cabbage, tomato and apple samples was studied. The haptens, 28-hemisuccinyl-TSN (TSN-S) and 28-hemiglutaryl-TSN (TSN-G) were synthesized by using esterification. Immunogen and coating antigen were synthesized by using the mixed anhydride reaction and active ester protocol, respectively. Rabbits were immunized with TSN-G-BSA and TSN-S-BSA. Using the selected antibody and coating antigen, an indirect competitive ELISA for TSN was developed, which showed an IC(50) value of 1.023 microg mL(-1), with a detection limit of 0.009 microg mL(-1). A direct competitive ELISA using an enzyme tracer was also developed. The assay showed an IC(50) value of 0.840 microg mL(-1) with a detection limit of 0.014 microg mL(-1). Both assays displayed high cross-reactivity to a closely structurally related compound. Recoveries of TSN from both immunoassays of fortified samples ranged from 76.4% to 113.2% and 75.1% to 132.3%, respectively. Linear regression analysis showed good correlation between the TSN concentrations derived from ELISA and HPLC analyses, which suggested that the ELISA is a convenient supplementary analytical tool for monitoring TSN.

Deregulated CDC25A expression promotes mammary tumorigenesis with genomic instability.

Checkpoint pathways help cells maintain genomic integrity, delaying cell cycle progression in response to various risks of fidelity, such as genotoxic stresses, compromised DNA replication, and impaired spindle control. Cancer cells frequently exhibit genomic instability, and recent studies showed that checkpoint pathways are likely to serve as a tumor-suppressive barrier in vivo. The cell cycle-promoting phosphatase CDC25A is an activator of cyclin-dependent kinases and one of the downstream targets for the CHK1-mediated checkpoint pathway. Whereas CDC25A overexpression is observed in various human cancer tissues, it has not been determined whether deregulated CDC25A expression triggers or promotes tumorigenesis in vivo. Here, we show that transgenic expression of CDC25A cooperates markedly with oncogenic ras or neu in murine mammary tumorigenesis. MMTV-CDC25A transgenic mice exhibit alveolar hyperplasia in the mammary tissue but do not develop spontaneous mammary tumors. The MMTV-CDC25A transgene markedly shortens latency of tumorigenesis in MMTV-ras mice. The MMTV-CDC25A transgene also accelerates tumor growth in MMTV-neu mice with apparent cell cycle miscoordination. CDC25A-overexpressing tumors, which invade more aggressively, exhibit various chromosomal aberrations on fragile regions, including the mouse counterpart of human 1p31-36, according to array-based comparative genomic hybridization and karyotyping. The chromosomal aberrations account for substantial changes in gene expression profile rendered by transgenic expression of CDC25A, including down-regulation of Trp73. These data indicate that deregulated control of cellular CDC25A levels leads to in vivo genomic instability, which cooperates with the neu-ras oncogenic pathway in mammary tumorigenesis.

Wnk1 kinase deficiency lowers blood pressure in mice: a gene-trap screen to identify potential targets for therapeutic intervention.

The availability of both the mouse and human genome sequences allows for the systematic discovery of human gene function through the use of the mouse as a model system. To accelerate the genetic determination of gene function, we have developed a sequence-tagged gene-trap library of >270,000 mouse embryonic stem cell clones representing mutations in approximately 60% of mammalian genes. Through the generation and phenotypic analysis of knockout mice from this resource, we are undertaking a functional screen to identify genes regulating physiological parameters such as blood pressure. As part of this screen, mice deficient for the Wnk1 kinase gene were generated and analyzed. Genetic studies in humans have shown that large intronic deletions in WNK1 lead to its overexpression and are responsible for pseudohypoaldosteronism type II, an autosomal dominant disorder characterized by hypertension, increased renal salt reabsorption, and impaired K+ and H+ excretion. Consistent with the human genetic studies, Wnk1 heterozygous mice displayed a significant decrease in blood pressure. Mice homozygous for the Wnk1 mutation died during embryonic development before day 13 of gestation. These results demonstrate that Wnk1 is a regulator of blood pressure critical for development and illustrate the utility of a functional screen driven by a sequence-based mutagenesis approach.

Overexpression of Cdc25B, an androgen receptor coactivator, in prostate cancer.

Cdc25B is a dual-specific phosphatase that mediates cell cycle progression by activating the cyclin-dependent kinases. It has been shown to possess oncogenic potential. To elucidate its potential contribution to human prostate cancer development, the expression profile of Cdc25B protein in human patients was analysed by immunohistocytochemistry. Cdc25B is frequently overexpressed in human prostate cancer tissues (29 of 30; 97%). In addition, the overexpression is more profound in the tumors of high combined Gleason scores and in late stages. Subsequently, we demonstrated that Cdc25B acts as a coactivator for AR in a hormone-dependent manner in the prostate cancer cell line, LNCaP. This coactivator function, surprisingly, is independent of its cell cycle functions. Cdc25B, on the other hand, directly interacts with AR as evidenced in GST-pull down and mammalian two-hybrid assays. In addition, it is also able to enhance AR-mediated transcription in synergy with other coactivators, including CREB-binding protein (CBP) and p300/CBP associated factor. Therefore, upregulation of Cdc25B in human prostate cancer and its interplay with AR may contribute to prostate cancer development.