[Mid-term outcome of deep layer repair with the long head of the biceps autograft bridging for Kim classification type Ⅰ A delaminiated rotator cuff tear]

Objective: To investigate the mid-term clinical outcome of deep layer repair with the long head of the biceps autograft bridging for Kim classification type ⅠA delaminated rotator cuff tear. Methods: A follow-up study. The clinical data of 42 consecutive patients with Kim classification type ⅠA delaminated rotator cuff tear admitted to the First Affiliated Hospital of Jinan University from January 2018 to June 2019 were retrospectively included. All patients underwent shoulder arthroscopic surgery. During the operation, the autogenous long head of the biceps tendon was transferred to repair the deep layer of delaminated rotator cuff tear. The preoperative and postoperative (last follow-up) visual analogue scale (VAS) for pain, University of California Los Angeles (UCLA) score, Constant-Murley shoulder score, range of motion (ROM) of the shoulder and radiographic results were statistically analyzed. Results: A total of 42 patients were included in this study. There were 18 males and 24 females, with an average age of (64.5±15.2) years and a mean follow-up of (43.9±7.1) months. At the last follow-up, ROM of abduction increased from 80.8°±26.5° to 154.2°±14.3°, and ROM of external rotation increased from 18.2°±13.6° to 31.8°±7.8°; the VAS score of pain decreased from (5.5±1.3) points to (0.7±0.7) points, the UCLA score increased from (21.3±3.7) points to (29.9±2.1) points, and the Constant-Murley score increased from (45.4±10.0) points to (87.2±4.8) points; the differences were all statistically significant (all P<0.001). The X-ray films showed that there were no upward of the humeral head in all the patients. MRI results indicated that rotator cuff re-teared in one case (Sugaya classification type Ⅲ), and healed in other cases (Sugaya classification type Ⅰ-Ⅱ). No complications such as upper limb nerve injury was found in all cases. Conclusion: Deep layer repair with the long head of the biceps autograft bridging can significantly alleviate the pain and improve the function of patients with Kim classification type ⅠA delaminated rotator cuff tear, and the incidence of retear is low.

Effects of Metformin and its Metabolite Guanylurea on Fathead Minnow (Pimephales promelas) Reproduction

Metformin, along with its biotransformation product guanylurea, is commonly observed in municipal wastewaters and subsequent surface waters. Previous studies in fish have identified metformin as a potential endocrine-active compound, but there are inconsistencies with regard to its effects. To further investigate the potential reproductive toxicity of metformin and guanylurea to fish, a series of experiments was performed with adult fathead minnows (Pimephales promelas). First, explants of fathead minnow ovary tissue were exposed to 0.001-100 µM metformin or guanylurea to investigate whether the compounds could directly perturb steroidogenesis. Second, spawning pairs of fathead minnows were exposed to metformin (0.41, 4.1, and 41 µg/L) or guanylurea (1.0, 10, and 100 µg/L) for 23 days to assess impacts on reproduction. Lastly, male fathead minnows were exposed to 41 µg/L metformin, 100 µg/L guanylurea, or a mixture of both compounds, with samples collected over a 96-h time course to investigate potential impacts to the hepatic transcriptome or metabolome. Neither metformin nor guanylurea affected steroid production by ovary tissue exposed ex vivo. In the 23 days of exposure, neither compound significantly impacted transcription of endocrine-related genes in male liver or gonad, circulating steroid concentrations in either sex, or fecundity of spawning pairs. In the 96-h time course, 100 µg guanylurea/L elicited more differentially expressed genes than 41 µg metformin/L and showed the greatest impacts at 96 h. Hepatic transcriptome and metabolome changes were chemical- and time-dependent, with the largest impact on the metabolome observed at 23 days of exposure to 100 µg guanylurea/L. Overall, metformin and guanylurea did not elicit effects consistent with reproductive toxicity in adult fathead minnows at environmentally relevant concentrations. Environ Toxicol Chem 2022;41:2708-2720. © 2022 SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Untargeted Lipidomics for Determining Cellular and Subcellular Responses in Zebrafish (Danio rerio) Liver Cells Following Exposure to Complex Mixtures in U.S. Streams

Surface waters often contain a variety of chemical contaminants potentially capable of producing adverse outcomes in both humans and wildlife due to impacts from industrial, urban, and agricultural activity. Here, we report the results of a zebrafish liver (ZFL) cell-based lipidomics approach to assess the potential ecotoxicological effects of complex contaminant mixtures using water collected from eight impacted streams across the United States mainland and Puerto Rico. We initially characterized the ZFL lipidome using high resolution mass spectrometry, resulting in the annotation of 508 lipid species covering 27 classes. We then identified lipid changes induced by all streamwater samples (nonspecific stress indicators) as well as those unique to water samples taken from specific streams. Subcellular impacts were classified based on organelle-specific lipid changes, including increased lipid saturation (endoplasmic reticulum stress), elevated bis(monoacylglycero)phosphate (lysosomal overload), decreased ubiquinone (mitochondrial dysfunction), and elevated ether lipids (peroxisomal stress). Finally, we demonstrate how these results can uniquely inform environmental monitoring and risk assessments of surface waters.

MiR-22-3p regulates the proliferation and invasion of Wilms' tumor cells by targeting AKT3

OBJECTIVE

In this study, the regulatory mechanism of miR-22-3p/AKT3 in the development of Wilms' tumor (WT) was investigated.

PATIENTS AND METHODS

Twenty-seven pairs of surgical tumor specimens and adjacent normal tissues were obtained from Jining No. 1 People's Hospital. The expression level of miR-22-3p in WT tissues and cell lines was measured by quantitative RT-PCR. MTT and transwell assays were performed to analyze cell proliferation and invasion in WT. The relationship between miR-22-3p and AKT3 was verified by a Dual-Luciferase assay. The protein expression of AKT3 was evaluated by Western blotting analysis.

RESULTS

MiR-22-3p was downregulated and AKT3 was upregulated in WT. Functionally, overexpression of miR-22-3p inhibited cell proliferation and invasion in WT. Moreover, miR-22-3p directly targets AKT3. The knockdown of AKT3 suppressed cell proliferation and invasion in WT. In addition, upregulation of AKT3 restored the tumor suppressive effect of miR-22-3p in WT.

CONCLUSIONS

MiR-22-3p inhibits the proliferation and invasion of WT cells by downregulating AKT3, indicating that miR-22-3p may be developed as a new biomarker for the diagnosis of WT.

Cell-Based Metabolomics for Untargeted Screening and Prioritization of Vertebrate-Active Stressors in Streams Across the United States

The U.S. Geological Survey and the U.S. Environmental Protection Agency have assessed contaminants in 38 streams across the U.S., using an extensive suite of target-chemical analysis methods along with a variety of biological effects tools. Here, we report zebrafish liver (ZFL) cell-culture based NMR metabolomic analysis of these split stream samples. We used this untargeted approach to evaluate the sites according to overall impact on the ZFL metabolome and found that neither the total number of organics detected at the sites, nor their cumulative concentrations, were good predictors of these impacts. Further, we used partial least squares regression to compare ZFL endogenous metabolite profiles to values for 455 potential stressors (organics, inorganics, and physical properties) measured in these waters and found that the profiles covaried with at most 280 of the stressors, which were subsequently ranked into quartiles based on the strength of their covariance. While contaminants of emerging concern (CECs) were well represented in the top, most strongly covarying quartile-suggesting considerable potential for eliciting biological responses at these sites-there was even higher representation of various well-characterized legacy contaminants (e.g., PCBs). These results emphasize the importance of complementing chemical analysis with untargeted bioassays to help focus regulatory efforts on the most significant ecosystem threats.

Sex-dependent effects of bisphenol A on type 1 diabetes development in non-obese diabetic (NOD) mice

Type 1 diabetes (T1D) is an autoimmune disease caused by immune-mediated pancreatic β-cell destruction. The endocrine disrupting chemical bisphenol A (BPA) has widespread human exposure and can modulate immune function and the gut microbiome (GMB), which may contribute to the increasing T1D incidence worldwide. It was hypothesized that BPA had sex-dependent effects on T1D by modulating immune homeostasis and GMB. Adult female and male non-obese diabetic (NOD) mice were orally administered BPA at environmentally relevant doses (30 or 300 µg/kg). Antibiotic-treated adult NOD females were exposed to 0 or 30 µg/kg BPA. BPA accelerated T1D development in females, but delayed males from T1D. Consistently, females had a shift towards pro-inflammation (e.g., increased macrophages and Bacteroidetes), while males had increases in anti-inflammatory immune factors and a decrease in both anti- and pro-inflammatory GMB. Although bacteria altered during sub-acute BPA exposure differed from bacteria altered from chronic BPA exposure in both sexes, the GMB profile was consistently pro-inflammatory in females, while males had a general decrease of both anti- and pro-inflammatory gut microbes. However, treatment of females with the antibiotic vancomycin failed to prevent BPA-induced glucose intolerance, suggesting changes in Gram-positive bacteria were not a primary mechanism. In conclusion, BPA exposure was found to have sex dimorphic effects on T1D with detrimental effects in females, and immunomodulation was identified as the primary mechanism.

Assessing the impact of wastewater treatment plant effluent on downstream drinking water-source quality using a zebrafish (Danio Rerio) liver cell-based metabolomics approach

Cell-based metabolomics was used in a proof-of-concept fashion to investigate the biological effects of contaminants as they traveled from a wastewater treatment plant (WWTP) discharge to a drinking water treatment plant (DWTP) intake in a surface-water usage cycle. Zebrafish liver (ZFL) cells were exposed to water samples collected along a surface-water flowpath, where a WWTP was located ∼14.5 km upstream of a DWTP. The sampling sites included: 1) upstream of the WWTP, 2) the WWTP effluent discharging point, 3) a proximal location downstream of the WWTP outfall, 4) a distal location downstream of the WWTP outfall, 5) the drinking water intake, and 6) the treated drinking water collected prior to discharge to the distribution system. After a 48-h laboratory exposure, the hydrophilic and lipophilic metabolites in ZFL cell extracts were analyzed by proton nuclear magnetic resonance (¹H NMR) spectroscopy and gas chromatography-mass spectrometry (GC-MS), respectively. Multivariate statistical analysis revealed distinct changes in metabolite profiles in response to WWTP effluent exposure. These effects on the hydrophilic metabolome gradually diminished downstream of the WWTP, becoming non-significant at the drinking water intake (comparable to upstream of the WWTP, p = 0.98). However, effects on the lipophilic metabolome increased significantly as the river flowed from the distal location downstream of the WWTP to the drinking water intake (p < 0.001), suggesting a source of bioactive compounds in this watershed other than the WWTP. ZFL cells exposed to treated drinking water did not exhibit significant changes in either the hydrophilic (p = 0.15) or lipophilic metabolome (p = 0.83) compared to the upstream site, suggesting that constituents in the WWTP effluent were efficiently removed by the drinking water treatment process. Impacts on ZFL cells from the WWTP effluent included disrupted energy metabolism, a global decrease in amino acids, and altered lipid metabolism pathways. Overall, this study demonstrated the utility of cell-based metabolomics as an effective tool for assessing the biological effects of complex pollutant mixtures, particularly when used as a complement to conventional chemical monitoring.

H9N2 influenza virus isolated from minks has enhanced virulence in mice

H9N2 is one of the major subtypes of influenza virus circulating in poultry in China, which has a wide host range from bird to mammals. Two H9N2 viruses were isolated from one mink farm in 2014. Phylogenetic analysis showed that internal genes of the H9N2 viruses have close relationship with those of H7N9 viruses. Interestingly, two H9N2 were separated in phylogenetic trees, indicating that they are introduced to this mink farm in two independent events. And further mice studies showed that one H9N2 caused obvious weight loss and 20% mortality in infected mice, while another virus did not cause any clinical sign in mice infected at the same dose. Genetic analysis indicated that the virulent H9N2 contain a natural mutation at 701N in PB2 protein, which was reported to contribute to mammalian adaptation. However, such substitution is absent in the H9N2 avirulent to mice. Circulation of H9N2 in mink may drive the virus to adapt mammals; continual surveillance of influenza virus in mink was warranted.

Derivation and Evaluation of Putative Adverse Outcome Pathways for the Effects of Cyclooxygenase Inhibitors on Reproductive Processes in Female Fish

Cyclooxygenase (COX) inhibitors are ubiquitous in aquatic systems and have been detected in fish tissues. The exposure of fish to these pharmaceuticals is concerning because COX inhibitors disrupt the synthesis of prostaglandins (PGs), which modulate a variety of essential biological functions, including reproduction. In this study, we investigated the effects of well-characterized mammalian COX inhibitors on female fathead minnow reproductive health. Fish (n = 8) were exposed for 96 h to water containing indomethacin (IN; 100 µg/l), ibuprofen (IB; 200 µg/l) or celecoxib (CX; 20 µg/l), and evaluated for effects on liver metabolome and ovarian gene expression. Metabolomic profiles of IN, IB and CX were not significantly different from control or one another. Exposure to IB and CX resulted in differential expression of comparable numbers of genes (IB = 433, CX = 545). In contrast, 2558 genes were differentially expressed in IN-treated fish. Functional analyses (canonical pathway and gene set enrichment) indicated extensive effects of IN on PG synthesis pathway, oocyte meiosis, and several other processes consistent with physiological roles of PGs. Transcriptomic data were congruent with PG data; IN-reduced plasma PG F2α concentration, whereas IB and CX did not. Five putative AOPs were developed linking the assumed molecular initiating event of COX inhibition, with PG reduction and the adverse outcome of reproductive failure via reduction of: (1) ovulation, (2) reproductive behaviors mediated by exogenous or endogenous PGs, and (3) oocyte maturation in fish. These pathways were developed using, in part, empirical data from the present study and other publicly available data.

Cytosol-Localized UDP-Xylose Synthases Provide the Major Source of UDP-Xylose for the Biosynthesis of Xylan and Xyloglucan

Xylan and xyloglucan are the two major cell wall hemicelluloses in plants, and their biosynthesis requires a steady supply of the sugar donor, UDP-xylose. UDP-xylose is synthesized through conversion of UDP-glucuronic acid (UDP-GlcA) by the activities of UDP-xylose synthase (UXS). There exist six UXS genes in the Arabidopsis thaliana genome; three of them (UXS1, UXS2 and UXS4) encode Golgi-localized enzymes and the other three (UXS3, UXS5 and UXS6) encode cytosol-localized enzymes. In this report, we investigated the contributions of these UXS genes in supplying UDP-xylose for the biosynthesis of xylan and xyloglucan. Expression analyses revealed that the six UXS genes exhibited distinct and overlapping expression patterns in different cell types of stems, root-hypocotyls and young seedlings, and that the relative enzymatic activity of UXS in the cytosol was 17 times higher than that in the Golgi. Among the six UXS genes, UXS3, UXS5 and UXS6 showed the highest expression in stems and were expressed predominantly in xylem cells and interfascicular fibers. Their predominant expression in secondary wall-forming cells was consistent with the finding that the expression of UXS3, UXS5 and UXS6 was directly activated by the secondary wall NAC master switches. Although simultaneous mutations of UXS1, UXS2 and UXS4 did not cause any apparent effects on plant growth and xylan biosynthesis, simultaneous down-regulation/mutations of UXS3, UXS5 and UXS6 led to a drastic reduction in secondary wall thickening, a severe deformation of xylem vessels, a significant decrease in xylan content without an apparent reduction in its chain length and an absence of GlcA side chains in xylan, which are reminiscent of the phenotypes of some known xylan-deficient mutants. Moreover, Immunolocalization with two xyloglucan monoclonal antibodies, LM15 and LM25, revealed a significant reduction in the amount of xylogulcan in the primary walls. These results demonstrate that the cytosol-localized UXS3, UXS5 and UXS6 play a predominant role in the supply of UDP-xylose for the biosynthesis of xylan and xyloglucan.

Linking field-based metabolomics and chemical analyses to prioritize contaminants of emerging concern in the Great Lakes basin

The ability to focus on the most biologically relevant contaminants affecting aquatic ecosystems can be challenging because toxicity-assessment programs have not kept pace with the growing number of contaminants requiring testing. Because it has proven effective at assessing the biological impacts of potentially toxic contaminants, profiling of endogenous metabolites (metabolomics) may help screen out contaminants with a lower likelihood of eliciting biological impacts, thereby prioritizing the most biologically important contaminants. The authors present results from a study that utilized cage-deployed fathead minnows (Pimephales promelas) at 18 sites across the Great Lakes basin. They measured water temperature and contaminant concentrations in water samples (132 contaminants targeted, 86 detected) and used ¹ H-nuclear magnetic resonance spectroscopy to measure endogenous metabolites in polar extracts of livers. They used partial least-squares regression to compare relative abundances of endogenous metabolites with contaminant concentrations and temperature. The results indicated that profiles of endogenous polar metabolites covaried with at most 49 contaminants. The authors identified up to 52% of detected contaminants as not significantly covarying with changes in endogenous metabolites, suggesting they likely were not eliciting measurable impacts at these sites. This represents a first step in screening for the biological relevance of detected contaminants by shortening lists of contaminants potentially affecting these sites. Such information may allow risk assessors to prioritize contaminants and focus toxicity testing on the most biologically relevant contaminants. Environ Toxicol Chem 2016;35:2493-2502. Published 2016 Wiley Periodicals Inc. on behalf of SETAC. This article is a US Government work and, as such, is in the public domain in the United States of America.

Biomarker analysis of liver cells exposed to surfactant-wrapped and oxidized multi-walled carbon nanotubes (MWCNTs)

Carbon nanotubes (CNTs) have great potential in industrial, consumer, and mechanical applications, based partly on their unique structural, optical and electronic properties. CNTs are commonly oxidized or treated with surfactants to facilitate aqueous solution processing, and these CNT surface modifications also increase possible human and ecological exposures to nanoparticle-contaminated waters. To determine the exposure outcomes of oxidized and surfactant-wrapped multiwalled carbon nanotubes (MWCNTs) on biochemical processes, metabolomics-based profiling of human liver cells (C3A) was utilized. Cells were exposed to 0, 10, or 100ng/mL of MWCNTs for 24 and 48h; MWCNT particle size distribution, charge, and aggregation were monitored concurrently during exposures. Following MWCNT exposure, cellular metabolites were extracted, lyophilized, and buffered for (1)H NMR analysis. Acquired spectra were subjected to both multivariate and univariate analysis to determine the consequences of nanotube exposure on the metabolite profile of C3A cells. Resulting scores plots illustrated temporal and dose-dependent metabolite responses to all MWCNTs tested. Loadings plots coupled with t-test filtered spectra identified metabolites of interest. XPS analysis revealed the presence of hydroxyl and carboxyl functionalities on both MWCNTs surfaces. Metal content analysis by ICP-AES indicated that the total mass concentration of the potentially toxic impurities in the exposure experiments were extremely low (i.e. [Ni]≤2×10(-10)g/mL). Preliminary data suggested that MWCNT exposure causes perturbations in biochemical processes involved in cellular oxidation as well as fluxes in amino acid metabolism and fatty acid synthesis. Dose-response trajectories were apparent and spectral peaks related to both dose and MWCNT dispersion methodologies were determined. Correlations of the significant changes in metabolites will help to identify potential biomarkers associated with carbonaceous nanoparticle exposure.

An Integrated Experimental and Computational Approach for Characterizing the Kinetics and Mechanism of Triadimefon Racemization

Enantiomers of chiral molecules commonly exhibit differing pharmacokinetics and toxicities, which can introduce significant uncertainty when evaluating biological and environmental fates and potential risks to humans and the environment. However, racemization (the irreversible transformation of one enantiomer into the racemic mixture) and enantiomerization (the reversible conversion of one enantiomer into the other) are poorly understood. To better understand these processes, we investigated the chiral fungicide, triadimefon, which undergoes racemization in soils, water, and organic solvents. Nuclear magnetic resonance (NMR) and gas chromatography / mass spectrometry (GC/MS) techniques were used to measure the rates of enantiomerization and racemization, deuterium isotope effects, and activation energies for triadimefon in H2 O and D2 O. From these results we were able to determine that: 1) the alpha-carbonyl carbon of triadimefon is the reaction site; 2) cleavage of the C-H (C-D) bond is the rate-determining step; 3) the reaction is base-catalyzed; and 4) the reaction likely involves a symmetrical intermediate. The B3LYP/6-311 + G** level of theory was used to compute optimized geometries, harmonic vibrational frequencies, nature population analysis, and intrinsic reaction coordinates for triadimefon in water and three racemization pathways were hypothesized. This work provides an initial step in developing predictive, structure-based models that are needed to identify compounds of concern that may undergo racemization. Chirality 28:633-641, 2016. © 2016 Wiley Periodicals, Inc.

Evolutionary Conservation of Xylan Biosynthetic Genes in Selaginella moellendorffii and Physcomitrella patens

Xylan is a major cross-linking hemicellulose in secondary walls of vascular tissues, and the recruitment of xylan as a secondary wall component was suggested to be a pivotal event for the evolution of vascular tissues. To decipher the evolution of xylan structure and xylan biosynthetic genes, we analyzed xylan substitution patterns and characterized genes mediating methylation of glucuronic acid (GlcA) side chains in xylan of the model seedless vascular plant, Selaginella moellendorffii, and investigated GT43 genes from S. moellendorffii and the model non-vascular plant, Physcomitrella patens, for their roles in xylan biosynthesis. Using nuclear magentic resonance spectroscopy, we have demonstrated that S. moellendorffii xylan consists of β-1,4-linked xylosyl residues subsituted solely with methylated GlcA residues and that xylans from both S. moellendorffii and P. patens are acetylated at O-2 and O-3. To investigate genes responsible for GlcA methylation of xylan, we identified two DUF579 genes in the S. moellendorffii genome and showed that one of them, SmGXM, encodes a glucuronoxylan methyltransferase capable of adding the methyl group onto the GlcA side chain of xylooligomers. Furthermore, we revealed that the two GT43 genes in S. moellendorffii, SmGT43A and SmGT43B, are functional orthologs of the Arabidopsis xylan backbone biosynthetic genes IRX9 and IRX14, respectively, indicating the evolutionary conservation of the involvement of two functionally non-redundant groups of GT43 genes in xylan backbone biosynthesis between seedless and seed vascular plants. Among the five GT43 genes in P. patens, PpGT43A was found to be a functional ortholog of Arabidopsis IRX9, suggesting that the recruitment of GT43 genes in xylan backbone biosynthesis occurred when non-vascular plants appeared on land.

Roles of Arabidopsis TBL34 and TBL35 in xylan acetylation and plant growth

Xylan is one of the major polymers in lignocellulosic biomass and about 60% of its xylosyl residues are acetylated at O-2 and/or O-3. Because acetylation of cell wall polymers contributes to biomass recalcitrance for biofuel production, it is important to investigate the biochemical mechanism underlying xylan acetylation, the knowledge of which could be applied to custom-design biomass composition tailored for biofuel production. In this report, we investigated the functions of Arabidopsis TRICHOME BIREFRINGENCE-LIKE 34 (TBL34) and TBL35, two DUF231-containing proteins, in xylan acetylation. The TBL34 gene was found to be specifically expressed in xylem cells in stems and root-hypocotyls, and both TBL34 and TBL35 were shown to be localized in the Golgi, where xylan biosynthesis occurs. Chemical analysis revealed that simultaneous mutations of TBL34 and TBL35 caused a mild decrease in xylan acetyl content and a specific reduction in xylan 3-O-monoacetylation and 2,3-di-O-acetylation. Furthermore, simultaneous mutations of TBL34, TBL35 and ESKIMO1 (ESK1) resulted in severely collapsed xylem vessels with altered secondary wall structure, and an extremely retarded plant growth. These findings indicate that TBL34 and TBL35 are putative acetyltransferases required for xylan 3-O-monoacetylation and 2,3-di-O-acetylation and that xylan acetylation is essential for normal secondary wall deposition and plant growth.

Mutations of Arabidopsis TBL32 and TBL33 Affect Xylan Acetylation and Secondary Wall Deposition

Xylan is a major acetylated polymer in plant lignocellulosic biomass and it can be mono- and di-acetylated at O-2 and O-3 as well as mono-acetylated at O-3 of xylosyl residues that is substituted with glucuronic acid (GlcA) at O-2. Based on the finding that ESK1, an Arabidopsis thaliana DUF231 protein, specifically mediates xylan 2-O- and 3-O-monoacetylation, we previously proposed that different acetyltransferase activities are required for regiospecific acetyl substitutions of xylan. Here, we demonstrate the functional roles of TBL32 and TBL33, two ESK1 close homologs, in acetyl substitutions of xylan. Simultaneous mutations of TBL32 and TBL33 resulted in a significant reduction in xylan acetyl content and endoxylanase digestion of the mutant xylan released GlcA-substituted xylooligomers without acetyl groups. Structural analysis of xylan revealed that the tbl32 tbl33 mutant had a nearly complete loss of 3-O-acetylated, 2-O-GlcA-substituted xylosyl residues. A reduction in 3-O-monoacetylated and 2,3-di-O-acetylated xylosyl residues was also observed. Simultaneous mutations of TBL32, TBL33 and ESK1 resulted in a severe reduction in xylan acetyl level down to 15% of that of the wild type, and concomitantly, severely collapsed vessels and stunted plant growth. In particular, the S2 layer of secondary walls in xylem vessels of tbl33 esk1 and tbl32 tbl33 esk1 exhibited an altered structure, indicating abnormal assembly of secondary wall polymers. These results demonstrate that TBL32 and TBL33 play an important role in xylan acetylation and normal deposition of secondary walls.

TBL3 and TBL31, Two Arabidopsis DUF231 Domain Proteins, are Required for 3-O-Monoacetylation of Xylan

Xylan, a major constituent of secondary cell walls, is made of a linear chain of β-1,4-linked xylosyl residues that are often substituted with glucuronic acid/methylglucuronic acid side chains and acetylated at O-2 and O-3. Previous studies have shown that ESK1, an Arabidopsis DUF231 protein, is an acetyltransferase catalyzing 2-O- and 3-O-monoacetylation of xylan. However, the esk1 mutation only causes a partial loss of xylan 2-O- and 3-O-monoacetylation, suggesting that additional xylan acetyltransferase activities are involved. In this report, we demonstrated the essential roles of two other Arabidopsis DUF231 genes, TBL3 and TBL31, in xylan acetylation. The expression of both TBL3 and TBL31 was shown to be induced by overexpression of the secondary wall master transcriptional regulator SND1 (secondary wall-associated NAC domain protein1) and down-regulated by simultaneous mutations of SND1 and its paralog NST1, indicating their involvement in secondary wall biosynthesis. β-Glucurondase (GUS) reporter gene analysis showed that TBL3 and TBL31 were specifically expressed in the xylem and interfascicular fibers in stems and the secondary xylem in root hypocotyls. Expression of fluorescent protein-tagged TBL3 and TBL31 in protoplasts revealed their localization in the Golgi, where xylan biosynthesis occurs. Although mutation of either TBL3 or TBL31 alone did not cause any apparent alterations in cell wall composition, their simultaneous mutations were found to result in a reduction in xylan acetylation. Further structural analysis demonstrated that the tbl3 tbl31 double mutant had a specific reduction in 3-O-acetylation of xylan. In addition, the tbl3 tbl31 esk1 triple mutant displayed a much more drastic decrease in 3-O-acetylation of xylan, indicating their functional redundancy in xylan 3-O-acetylation. These findings indicate that TBL3 and TBL31 are secondary wall-associated DUF231 genes specifically involved in xylan 3-O-acetylation.

Gene transcription, metabolite and lipid profiling in eco-indicator daphnia magna indicate diverse mechanisms of toxicity by legacy and emerging flame-retardants

The use of chemical flame-retardants (FR) in consumer products has steadily increased over the last 30 years. Toxicity data exist for legacy FRs such as pentabromodiphenyl ether (pentaBDE), but less is known about effects of new formulations. To address this issue, the toxicity of seven FR chemicals and formulations was assessed on the freshwater crustacean Daphnia magna. Acute 48-h nominal LC50 values for penta- and octabromodiphenyl ether (pentaBDE, octaBDE), Firemaster 550 (FM550), Firemaster BZ-54 (BZ54), bis(2-ethylhexyl) tetrabromophthalate (BEH-TEBP), triphenyl phosphate (TPhP), and nonbrominated BEH-TEBP analog bis(2-ethylhexyl) phthalate (BEHP) ranged from 0.058 mg/L (pentaBDE) to 3.96 mg/L (octaBDE). mRNA expression, (1)H NMR-based metabolomic and lipidomic profiling at 1/10 LC50 revealed distinct patterns of molecular response for each exposure, suggesting pentaPBDE affects transcription and translation, octaBDE and BEH-TEBP affect glycosphingolipid biosynthesis and BZ54 affects Wnt and Hedgehog signal pathways as well as glycosaminoglycan degradation. Brominated components of FM550 (i.e., BZ54) were significantly higher in Daphnia after 48 h following 1/10 LC50 exposure. FM550 elicited significant mRNA changes at five concentrations across a range from 1/10(6) LC50 to 1/2 LC50. Analyses suggest FM550 impairs nutrient utilization or uptake in Daphnia.

Modification of the degree of 4-O-methylation of secondary wall glucuronoxylan

Plant secondary walls are the major constituent of plant biomass targeted for second-generation biofuel production. Therefore, a thorough understanding of how secondary walls are constructed is critical for a better utilization of plant biomass for biofuel production. One of the major components in secondary walls is xylan, which is composed of a linear chain of β-1,4-linked xylosyl residues. In Arabidopsis, about 10% of xylosyl residues in xylan are substituted with glucuronic acid (GlcA), of which 60% are methylated at O-4. By contrast, all of the GlcA substituents in Populus xylan are methylated at O-4. It is not known how the degree of GlcA methylation in xylan is controlled. In this report, we demonstrated that simultaneous T-DNA knockout mutations of the three glucuronoxylan methyltransferase (GXM) genes, GXM1, GXM2, and GXM3/GXMT1, which are specifically expressed in secondary wall-forming cells, led to a complete loss of GlcA methylation in xylan in Arabidopsis stems. Overexpression of GXM2 and GXM3 in wild-type Arabidopsis resulted in an up to 5-fold increase in glucuronoxylan methyltransferase activity and as a result, up to 90% of the GlcA side chains in xylan were methylated as opposed to 60% seen in the wild type. The increased degree of GlcA methylation in xylan had no discernable effects on cell wall sugar composition and lignin monomer composition. These results reveal that the activities of GXM1, GXM2 and GXM3 are responsible for all of the GlcA methylation in xylan in Arabidopsis stems and that the degree of GlcA methylation in xylan can be modified by altered expression of GXMs.

Enhanced tumor delivery of gemcitabine via PEG-DSPE/TPGS mixed micelles

Gemcitabine is a potent anticancer drug approved for the treatment of pancreatic, non-small-cell lung, breast, and ovarian cancers. The major deficiencies of current gemcitabine therapy, however, are its rapid metabolic inactivation and narrow therapeutic window. Herein, we employed polyethylene glycol-b-distearoylphosphatidylethanolamine (PEG-DSPE)/tocopheryl polyethylene glycol 1000 succinate (TPGS) mixed micelles as a delivery system, to improve the pharmacokinetic characteristics of gemcitabine and enhance its antitumor efficacy. By conjugating stearic acid to gemcitabine and subsequently encapsulating stearoyl gemcitabine (GemC18) within PEG-DSPE/TPGS mixed micelles, the deamination of gemcitabine was delayed in vitro and in vivo. Importantly, compared to free gemcitabine, GemC18-loaded micelles pronouncedly prolonged the circulation time of gemcitabine and elevated its concentration in the tumor by 3-fold, resulting in superior antitumor efficacy in mice bearing human pancreatic cancer BxPC-3 xenografts. Our findings demonstrate the promise of PEG-DSPE/TPGS mixed micelles as a nanocarrier system for the delivery of gemcitabine to achieve safer and more efficacious therapeutic outcomes.

Metabolomics for in situ environmental monitoring of surface waters impacted by contaminants from both point and nonpoint sources

We investigated the efficacy of metabolomics for field-monitoring of fish exposed to wastewater treatment plant (WWTP) effluents and nonpoint sources of chemical contamination. Lab-reared male fathead minnows (Pimephales promelas, FHM) were held in mobile monitoring units and exposed on-location to surface waters upstream and downstream of the effluent point source, as well as to the actual effluent at three different WWTP sites in Minnesota. After four days of exposure, livers were collected, extracted, and analyzed by (1)H NMR spectroscopy and GC-MS to characterize responses of the hepatic metabolome. Multivariate statistical analysis revealed distinct metabolite profile changes in response to effluent exposure from each of the three WWTPs. Differences among locations (i.e., upstream, downstream, and effluent) within each of the three sites were also identified. These observed differences comport with land-use and WWTP characteristics at the study sites. For example, at one of the sites, the metabolomic analyses suggested a positive interactive response from exposure to WWTP effluent and nearby nonpoint (likely agricultural related) contamination. These findings demonstrate the utility of metabolomics as a field-based technique for monitoring the exposure of fish to impacted surface waters.

Identification and biochemical characterization of four wood-associated glucuronoxylan methyltransferases in Populus

Wood is one of the promising bioenergy feedstocks for lignocellulosic biofuel production. Understanding how wood components are synthesized will help us design strategies for better utilization of wood for biofuel production. One of the major wood components is xylan, in which about 10% of xylosyl residues are substituted with glucuronic acid (GlcA) side chains. All the GlcA side chains of xylan in wood of Populus trichocarpa are methylated, which is different from Arabidopsis xylan in which about 60% of GlcA side chains are methylated. Genes responsible for methylation of GlcA side chains in Populus xylan have not been identified. Here, we report genetic and biochemical analyses of four DUF579 domain-containing proteins, PtrGXM1, PtrGXM2, PtrGXM3 and PtrGXM4, from Populus trichocarpa and their roles in GlcA methylation in xylan. The PtrGXM genes were found to be highly expressed in wood-forming cells and their encoded proteins were shown to be localized in the Golgi. When overexpressed in the Arabidopsis gxm1/2/3 triple mutant, PtrGXMs were able to partially complement the mutant phenotypes including defects in glucuronoxylan methyltransferase activity and GlcA methylation in xylan, indicating that PtrGXMs most likely function as glucuronoxylan methyltransferases. Direct evidence was provided by enzymatic analysis of recombinant PtrGXM proteins showing that they possessed a methyltransferase activity capable of transferring the methyl group onto GlcA-substituted xylooligomers. Kinetic analysis showed that PtrGXMs exhibited differential affinities toward the GlcA-substituted xylooligomer acceptor with PtrGXM3 and PtrGXM4 having 10 times higher K_m values than PtrGXM1 and PtrGXM2. Together, these findings indicate that PtrGXMs are methyltransferases mediating GlcA methylation in Populus xylan during wood formation.

Functional roles of rice glycosyltransferase family GT43 in xylan biosynthesis

Xylan is the major hemicellulose present in both primary and secondary cell walls of rice vegetative tissues. Since xylan is one of the factors contributing to biomass recalcitrance, understanding how xylan is synthesized in rice will potentially provide tools to modify grass biomass composition better suited for biofuel production. Studies of xylan biosynthesis in Arabidopsis have revealed that family GT43 glycosyltransferases, which form 2 functionally nonredundant groups, IRX9/IRX9 homolog and IRX14/IRX14 homolog, are required for xylan backbone elongation. The rice genome harbors 10 genes encoding family GT43 members and it is currently unknown whether they are all involved in xylan biosynthesis. In this report, we performed biochemical analysis of xylan xylosyltransferase activity in rice stem microsomes and investigated the roles of 4 representative rice GT43 members, OsGT43A (LOC_Os05 g03174), OsGT43E (LOC_Os05 g48600), OsGT43H (LOC_Os04 g01280), and OsGT43J (LOC_Os06 g47340), in xylan biosynthesis. OsGT43 proteins were shown to be localized in the Golgi, where xylan biosynthesis occurs. Complementation analysis by expression of OsGT43s in Arabidopsis irx9 and irx14 mutants demonstrated that OsGT43A and OsGT43E but not OsGT43H and OsGT43J were able to rescue the mutant phenotypes conferred by the irx9 mutation, including defective stem mechanical strength, vessel morphology, xylan content, GlcA side chains, xylan chain length, and xylosyltransferase activity. On the other hand, OsGT43J but not OsGT43A, OsGT43E, and OsGT43H restored the defective xylan phenotype in the irx14 mutant. These results indicate that the rice GT43 family evolved to retain the involvement of 2 functionally nonredundant groups, OsGT43A and OsGT43E (IRX9 homologs) vs. OsGT43J (an IRX14 homolog), in xylan backbone biosynthesis.

Identification of a disaccharide side chain 2-O-α-D-galactopyranosyl-α-D-glucuronic acid in Arabidopsis xylan

Arabidopsis xylan consists of a linear chain of β-1,4-linked D-xylosyl residues, about 10% of which are substituted with single residues of α-D-glucuronic acid (GlcA) or 4-O-methyl-α-D-glucuronic acid (MeGlcA) at O-2. In addition, about 60% of xylosyl residues are acetylated at O-2 and/or O-3. Previous studies have identified a number of genes responsible for elongation of the xylan backbone, addition of the GlcA substituents, and methylation of the GlcA residues. Yuan et al. (2013) have recently reported that the 2-O- and 3-O-monoacetylation of xylosyl residues in Arabidopsis xylan requires a DUF231 domain-containing protein, ESKIMO1 (ESK1), and proposed that ESK1 and its homologs are putative acetyltransferases responsible for xylan acetylation. It was noticed that the (1)H nuclear magnetic resonance (NMR) spectra of the acetylated xylan from the esk1 mutant and the wild-type Arabidopsis exhibited a prominent proton signal peak at 5.42 ppm in addition to resonances corresponding to known acetylated structural groups of xylan. Here, we performed detailed structural investigation of wild-type Arabidopsis acetylated xylan using 2-dimensional (1)H- (1)H and (1)H- (13)C NMR spectroscopy and found that the signal peak at 5.42 ppm in the (1)H NMR spectrum was attributed to GlcA residues substituted at O-2 with α-D-galactose (Gal), indicating the presence of Gal-GlcA disaccharide side chains in Arabidopsis xylan. This finding was further supported by analysis of endoxylanase-digested xylan using matrix-assisted laser desorption ionization-time-of-flight mass spectrometry. Our study demonstrates that Arabidopsis xylan contains Gal-GlcA disaccharide side chains in addition to GlcA, MeGlcA, and acetyl substitutions.

Alterations of the degree of xylan acetylation in Arabidopsis xylan mutants

Xylan is the second most abundant polysaccharide in secondary walls of dicot plants and one of its structural features is the high degree of acetylation of xylosyl residues. In Arabidopsis, about 60% of xylosyl residues in xylan are acetylated and the biochemical mechanisms controlling xylan acetylation are largely unknown. A recent report by Yuan et al. (2013) revealed the essential role of a DUF231 domain-containing protein, ESKIMO1 (ESK1), in xylan acetylation in Arabidopsis as the esk1 mutation caused specific reductions in the degree of xylan 2-O or 3-O-monoacetylation and in the activity of xylan acetyltransferase. Interestingly, the esk1 mutation also resulted in an elevation of glucuronic acid (GlcA) substitutions in xylan. Since GlcA substitutions in xylan occur at the O-2 position of xylosyl residues, it is plausible that the increase in GlcA substitutions in the esk1 mutant is attributed to the reduction in acetylation at O-2 of xylosyl residues, which renders more O-2 positions available for GlcA substitutions. Here, we investigated the effect of removal of GlcA substitutions on the degree of xylan acetylation. We found that a complete loss of GlcA substitutions in the xylan of the gux1/2/3 triple mutant led to a significant increase in the degree of xylan acetylation, indicating that xylan acetyltransferases and glucuronyltransferases compete with each other for xylosyl residues for their acetylation or GlcA substitutions in planta. In addition, detailed structure analysis of xylan from the rwa1/2/3/4 quadruple mutant revealed that it had a uniform reduction of acetyl substitutions at different positions of the xylosyl residues, which is consistent with the proposed role of RWAs as acetyl coenzyme A transporters. The significance of these findings is discussed.

Field-based approach for assessing the impact of treated pulp and paper mill effluent on endogenous metabolites of fathead minnows (Pimephales promelas)

A field-based metabolomic study was conducted during a shutdown of a pulp and paper mill (PPM) to assess the impacts of treated PPM effluent on endogenous polar metabolites in fathead minnow (FHM; Pimephales promelas) livers. Caged male and female FHMs were deployed at a Great Lakes area of concern during multiple periods (pre-, during, and post-shutdown) near the outflow for a wastewater treatment plant. Influent to this plant is typically 40% PPM effluent by volume. Additional FHMs were exposed to reference lake water under laboratory conditions. A bioassay using T47D-KBluc cells showed that estrogenic activity of receiving water near the outflow declined by 46% during the shutdown. We then used (1)H NMR spectroscopy and principal component analysis to profile abundances of hepatic endogenous metabolites for FHMs. Profiles for males deployed pre-shutdown in receiving water were significantly different from those for laboratory-control males. Profiles were not significantly different for males deployed during the shutdown, but they were significant again for those deployed post-shutdown. Impacts of treated effluent from this PPM were sex-specific, as differences among profiles of females were largely nonsignificant. Thus, we demonstrate the potential utility of field-based metabolomics for performing biologically based exposure monitoring and evaluating remediation efforts occurring throughout the Great Lakes and other ecosystems.

The Arabidopsis DUF231 domain-containing protein ESK1 mediates 2-O- and 3-O-acetylation of xylosyl residues in xylan

Xylan, a major polysaccharide in plant lignocellulosic biomass, is acetylated at O-2 and/or O-3 and its acetylation impedes the use of biomass for biofuel production. Currently, it is not known what genes encode acetyltransferases that are responsible for xylan O-acetylation. In this report, we demonstrate an essential role for the Arabidopsis gene ESKIMO1 (ESK1) in xylan O-acetylation during secondary wall biosynthesis. ESK1 expression was found to be regulated by the secondary wall master regulator SND1 (secondary wall-associated NAC domain protein1) and specifically associated with secondary wall biosynthesis. Its encoded protein was localized in the Golgi, the site of xylan biosynthesis. The esk1 mutation caused reductions in secondary wall thickening and stem mechanical strength. Chemical analyses of cell walls revealed that although the esk1 mutation did not cause apparent alterations in the xylan chain length and the abundance of the reducing end sequence, it resulted in a significant reduction in the degree of xylan acetylation. The reduced acetylation of esk1 xylan rendered it more accessible and digestible by endoxylanase, leading to generation of shorter xylooligomers compared with the wild type. Further structural analysis of xylan showed that the esk1 mutation caused a specific reduction in 2-O- and 3-O-monoacetylation of xylosyl residues but not in 2,3-di-O-acetylation or 3-O-acetylation of xylosyl residues substituted at O-2 with glucuronic acid. Consistent with ESK1's involvement in xylan O-acetylation, an activity assay revealed that the esk1 mutation led to a significant decrease in xylan acetyltransferase activity. Together, these results demonstrate that ESK1 is a putative xylan acetyltransferase required for 2-O- and 3-O-monoacetylation of xylosyl residues and indicate the complexity of the biochemical mechanism underlying xylan O-acetylation.

Notch1 overexpression promotes cell growth and tumor angiogenesis in myeloma

Patients with multiple myeloma (MM) have increased bone marrow angiogenesis, but the angiogenic properties of myeloma cells and the mechanism of MM-induced angiogenesis have not been completely clarified. Notch1 signal has been identified as a critical factor in the regulation of vessel formation. However, the role of Notch1 in the angiogenesis of MM is unclear. We constitutively overexpressed active Notch1 in RPMI8226 cells to explore the effect of Notch1 signaling on cell growth and tumor angiogenesis in vivo and in vitro. We found that Notch1 overexpression promoted myeloma cells growth and increased drug resistance. Moreover, vascular endothelial growth factor (VEGF) expression was increased. Finally, our in vitro results were supported by the in vivo finding in human myeloma xenograft Nonobese diabetic/severe combined immunodeficient (NOD/SCID) models. Notch1 overexpression in MM cells resulted in up-regulation of VEGF expression, promotion of tumor growth, and increased microvessel density (MVD). Our study suggests that Notch1-induced angiogenesis is partly due to activation of VEGF pathway.

Impacts of 17α-ethynylestradiol exposure on metabolite profiles of zebrafish (Danio rerio) liver cells

Endocrine disrupting chemicals (EDCs) that are frequently detected in bodies of water downstream from sewage treatment facilities can have adverse impacts on fish and other aquatic organisms. To properly assess risk(s) from EDCs, tools are needed that can establish linkages from chemical exposures to adverse outcomes. Traditional methods of testing chemical exposure and toxicity using experimental animals are excessively resource- and time-consuming. In line with EPA's goal of reducing animal use in testing, these traditional screening methods may not be sustainable in the long term, given the ever increasing number of chemicals that must be tested for safety. One of the most promising ways to reduce costs and increase throughput is to use cell cultures instead of experimental animals. In accordance with National Research Council's vision on 21st century toxicity testing, we have developed a cell culture-based metabolomics approach for this application. Using a zebrafish (Danio rerio) liver cell line (ZFL), we have applied NMR-based metabolomics to investigate responses of ZFL cells exposed to 17α-ethynylestradiol (EE2). This analysis showed that metabolite changes induced by EE2 exposure agree well with known impacts of estrogens on live fish. The results of this study demonstrate the potential of cell-based metabolomics to assess chemical exposure and toxicity for regulatory application.

Combined delivery of paclitaxel and tanespimycin via micellar nanocarriers: pharmacokinetics, efficacy and metabolomic analysis

Background

Despite the promising anticancer efficacy observed in preclinical studies, paclitaxel and tanespimycin (17-AAG) combination therapy has yielded meager responses in a phase I clinical trial. One serious problem associated with paclitaxel/17-AAG combination therapy is the employment of large quantities of toxic organic surfactants and solvents for drug solubilization. The goal of this study was to evaluate a micellar formulation for the concurrent delivery of paclitaxel and 17-AAG in vivo.

Methodology/Principal Findings

Paclitaxel/17-AAG-loaded micelles were assessed in mice bearing human ovarian tumor xenografts. Compared with the free drugs at equivalent doses, intravenous administration of paclitaxel/17-AAG-loaded micelles led to 3.5- and 1.7-fold increase in the tumor concentrations of paclitaxel and 17-AAG, respectively, without significant altering drug levels in normal organs. The enhanced tumor accumulation of the micellar drugs was further confirmed by the whole-body near infrared imaging using indocyanine green-labeled micelles. Subsequently, the anticancer efficacy of paclitaxel/17-AAG-loaded micelles was examined in comparison with the free drugs (weekly 20 mg/kg paclitaxel, twice-weekly 37.5 mg/kg 17-AAG). We found that paclitaxel/17-AAG-loaded micelles caused near-complete arrest of tumor growth, whereas the free drug-treated tumors experienced rapid growth shortly after the 3-week treatment period ended. Furthermore, comparative metabolomic profiling by proton nuclear magnetic resonance revealed significant decrease in glucose, lactate and alanine with simultaneous increase in glutamine, glutamate, aspartate, choline, creatine and acetate levels in the tumors of mice treated with paclitaxel/17-AAG-loaded micelles.

Conclusions/Significance

We have demonstrated in the current wok a safe and efficacious nano-sized formulation for the combined delivery of paclitaxel and 17-AAG, and uncovered unique metabolomic signatures in the tumor that correlate with the favorable therapeutic response to paclitaxel/17-AAG combination therapy.

Three Arabidopsis DUF579 domain-containing GXM proteins are methyltransferases catalyzing 4-o-methylation of glucuronic acid on xylan

Xylan is made of a linear chain of β-1,4-linked xylosyl residues, some of which are substituted with side chains, such as glucuronic acid (GlcA), methylglucuronic acid (MeGlcA) and arabinose, depending on the source of xylan. Although past studies have revealed a number of genes involved in the elongation of the xylan backbone and the addition of GlcA and arabinosyl side chains, no genes have been shown to be implicated in glucuronoxylan methylation. In this report, we investigated the roles of three Arabidopsis genes, namely GLUCURONOXYLAN METHYLTRANSFERASE1 (GXM1), GXM2 and GXM3, in xylan biosynthesis. The GXM1/2/3 genes were found to be expressed in secondary wall-forming cells and their expression was regulated by SND1, a secondary wall master transcriptional switch. Their encoded proteins were shown to be located in the Golgi, where xylan biosynthesis occurs. Chemical analysis of cell wall sugars from single and double mutants of these genes revealed that although no alterations in the amount of xylose were observed, a significant reduction in the level of MeGlcA was evident in the gxm3 single mutant and the gxm double mutants. Structural analysis of xylan demonstrated that the gxm mutations caused a specific defect in GlcA methylation on xylan without affecting the frequency of xylan substitution. Only about 10% of the GlcA residues on xylan were methylated in the gxm2/3 double mutant, whereas in the wild type 60% of the GlcA residues were methylated. Furthermore, an activity assay demonstrated that recombinant GXM proteins exhibited a methyltransferase activity capable of transferring the methyl group from S-adenosylmethionine onto GlcA-substituted xylooligomers and simultaneous mutations of GXM2/3 genes caused a loss of such a methyltransferase activity. Taken together, our results provide the first line of genetic and biochemical evidence that the three DUF579 domain-containing proteins, GXM1, GXM2 and GXM3, are methyltransferases catalyzing 4-O-methylation of GlcA side chains on xylan.

Metabolite profiling and a transcriptional activation assay provide direct evidence of androgen receptor antagonism by bisphenol A in fish

Widespread environmental contamination by bisphenol A (BPA) has created the need to fully define its potential toxic mechanisms of action (MOA) to properly assess human health and ecological risks from exposure. Although long recognized as an estrogen receptor (ER) agonist, some data suggest that BPA may also behave as an androgen receptor (AR) antagonist. However, direct evidence of this activity is deficient. To address this knowledge gap, we employed a metabolomic approach using in vivo exposures of fathead minnows (FHM; Pimephales promelas ) to BPA either alone or in a binary mixture with 17β-trenbolone (TB), a strong AR agonist. Changes in liver metabolite profiles in female FHM in response to these exposures were determined using high resolution (1)H NMR spectroscopy and multivariate and univariate statistics. Using this approach, we observed clear evidence of the ability of BPA to mitigate the impact of TB, consistent with an antiandrogenic MOA. In addition, a transcriptional activation assay with the FHM AR was used to confirm the AR antagonistic activity of BPA in vitro. The results of these in vivo and in vitro analyses provide strong and direct evidence for ascribing an antiandrogenic MOA to BPA in vertebrates.

Arabidopsis GUX proteins are glucuronyltransferases responsible for the addition of glucuronic acid side chains onto xylan

Xylan, the second most abundant cell wall polysaccharide, is composed of a linear backbone of β-(1,4)-linked xylosyl residues that are often substituted with sugar side chains, such as glucuronic acid (GlcA) and methylglucuronic acid (MeGlcA). It has recently been shown that mutations of two Arabidopsis family GT8 genes, GUX1 and GUX2, affect the addition of GlcA and MeGlcA to xylan, but it is not known whether they encode glucuronyltransferases (GlcATs) or indirectly regulate the GlcAT activity. In this study, we performed biochemical and genetic analyses of three Arabidopsis GUX genes to determine their roles in the GlcA substitution of xylan and secondary wall deposition. The GUX1/2/3 genes were found to be expressed in interfascicular fibers and xylem cells, the two major types of secondary wall-containing cells that have abundant xylan. When expressed in tobacco BY2 cells, the GUX1/2/3 proteins exhibited an activity capable of transferring GlcA residues from the UDP-GlcA donor onto xylooligomer acceptors, demonstrating that these GUX proteins possess xylan GlcAT activity. Analyses of the single, double and triple gux mutants revealed that simultaneous mutations of all three GUX genes led to a complete loss of GlcA and MeGlcA side chains on xylan, indicating that all three GUX proteins are involved in the GlcA substitution of xylan. Furthermore, a complete loss of GlcA and MeGlcA side chains in the gux1/2/3 triple mutant resulted in reduced secondary wall thickening, collapsed vessel morphology and reduced plant growth. Together, our results provide biochemical and genetic evidence that GUX1/2/3 are GlcATs responsible for the GlcA substitution of xylan, which is essential for normal secondary wall deposition and plant development.

The four Arabidopsis reduced wall acetylation genes are expressed in secondary wall-containing cells and required for the acetylation of xylan

Xylan is one of the major polysaccharides in cellulosic biomass, and understanding the mechanisms underlying xylan biosynthesis will potentially help us design strategies to produce cellulosic biomass better suited for biofuel production. Although a number of genes have been shown to be essential for xylan biosynthesis, genes involved in the acetylation of xylan have not yet been identified. Here, we report the comprehensive genetic and functional studies of four Arabidopsis REDUCED WALL ACETYLATION (RWA) genes and demonstrate their involvement in the acetylation of xylan during secondary wall biosynthesis. It was found that the RWA genes were expressed in cells undergoing secondary wall thickening and their expression was regulated by SND1, a transcriptional master switch of secondary wall biosynthesis. The RWA proteins were shown to be localized in the Golgi, where xylan biosynthesis occurs. Analyses of a suite of single, double, triple and quadruple rwa mutants revealed a significant reduction in the secondary wall thickening and the stem mechanical strength in the quadruple rwa1/2/3/4 mutant but not in other mutants. Further chemical and structural analyses of xylan demonstrated that the rwa1/2/3/4 mutations resulted in a reduction in the amount of acetyl groups on xylan. In addition, the ratio of non-methylated to methylated glucuronic acid side chains was altered in the rwa1/2/3/4 mutant. Together, our results demonstrate that the four Arabidopsis RWA genes function redundantly in the acetylation of xylan during secondary wall biosynthesis.

Multi-drug delivery to tumor cells via micellar nanocarriers

The aim of this study was to develop micellar nanocarriers for concomitant delivery of paclitaxel and 17-allylamino-17-demethoxygeldanamycin (17-AAG) for cancer therapy. Paclitaxel and 17-AAG were simultaneously loaded into polymeric micelles by a solvent evaporation method. Two candidate nanocarrier constructs, polyethylene glycol-poly(D, L-lactic acid) (PEG-PLA) micelles and PEG-distearoylphosphatidylethanolamine/tocopheryl polyethylene glycol 1000 (PEG-DSPE/TPGS) mixed micelles, were assessed for the release kinetics of the loaded drugs. Compared to PEG-PLA micelles, entrapment of paclitaxel and 17-AAG into PEG-DSPE/TPGS mixed micelles resulted in significantly prolonged release half-lives. The simultaneous incorporation of paclitaxel and 17-AAG into PEG-DSPE/TPGS mixed micelles was confirmed by (1)H NMR analysis. Paclitaxel/17-AAG-loaded PEG-DSPE/TPGS mixed micelles were as effective in blocking the proliferation of human ovarian cancer SKOV-3 cells as the combined free drugs. PEG-DSPE/TPGS mixed micelles may provide a novel and advantageous delivery approach for paclitaxel/17-AAG combination therapy.

Molecular dissection of xylan biosynthesis during wood formation in poplar

Xylan, being the second most abundant polysaccharide in dicot wood, is considered to be one of the factors contributing to wood biomass recalcitrance for biofuel production. To better utilize wood as biofuel feedstock, it is crucial to functionally characterize all the genes involved in xylan biosynthesis during wood formation. In this report, we investigated roles of poplar families GT43 and GT8 glycosyltransferases in xylan biosynthesis during wood formation. There exist seven GT43 genes in the genome of poplar (Populus trichocarpa), five of which, namely PtrGT43A, PtrGT43B, PtrGT43C, PtrGT43D, and PtrGT43E, were shown to be highly expressed in the developing wood and their encoded proteins were localized in the Golgi. Comprehensive genetic complementation coupled with chemical analyses demonstrated that overexpression of PtrGT43A/B/E but not PtrGT43C/D was able to rescue the xylan defects conferred by the Arabidopsis irx9 mutant, whereas overexpression of PtrGT43C/D but not PtrGT43A/B/E led to a complementation of the xylan defects in the Arabidopsis irx14 mutant. The essential roles of poplar GT43 members in xylan biosynthesis was further substantiated by RNAi down-regulation of GT43B in the hybrid poplar (Populus alba x tremula) leading to reductions in wall thickness and xylan content in wood, and an elevation in the abundance of the xylan reducing end sequence. Wood digestibility analysis revealed that cellulase digestion released more glucose from the wood of poplar GT43B RNAi lines than the control wood, indicating a decrease in wood biomass recalcitrance. Furthermore, RNAi down-regulation of another poplar wood-associated glycosyltransferase, PoGT8D, was shown to cause decreases in wall thickness and xylan content as well as in the abundance of the xylan reducing end sequence. Together, these findings demonstrate that the poplar GT43 members form two functionally non-redundant groups, namely PtrGT43A/B/E as functional orthologs of Arabidopsis IRX9 and PtrGT43C/D as functional orthologs of Arabidopsis IRX14, all of which are involved in the biosynthesis of xylan backbones, and that the poplar GT8D is essential for the biosynthesis of the xylan reducing end sequence.

Use of gene expression, biochemical and metabolite profiles to enhance exposure and effects assessment of the model androgen 17β-trenbolone in fish

The impact of exposure by water to a model androgen, 17β-trenbolone (TRB), was assessed in fathead minnows using an integrated molecular approach. This included classical measures of endocrine exposure such as impacts on testosterone (T), 17β-estradiol (E2), and vitellogenin (VTG) concentrations in plasma, as well as determination of effects on the hepatic metabolome using proton nuclear magnetic resonance spectroscopy. In addition, the rates of production of T and E2 in ovary explants were measured, as were changes in a number of ovarian gene transcripts hypothesized to be relevant to androgen exposure. A temporally intensive 16-d test design was used to assess responses both during and after the TRB exposure (i.e., depuration/recovery). This strategy revealed time-dependent responses in females (little impact was seen in the males), in which changes in T and E2 production in the ovary, as well as levels in plasma, declined rapidly (within 1 d), followed shortly by a return to control levels. Gene expression measurements revealed dynamic control of transcript levels in the ovary and suggested potential mechanisms for compensation during the exposure phase of the test. Proton nuclear magnetic resonance spectroscopy revealed a number of hepatic metabolite changes that exhibited strong time and dose dependence. Furthermore, TRB appeared to induce the hepatic metabolome of females to become more like that of males at both high test concentrations of TRB (472 ng/L) and more environmentally relevant levels (33 ng/L).

Impacts of an anti-androgen and an androgen/anti-androgen mixture on the metabolite profile of male fathead minnow urine

Male and female fathead minnows (Pimephales promelas, FHM) were exposed via water to 20 or 200 microg/L of cyproterone acetate (CA), a model androgen receptor (AR) antagonist. FHM were also exposed to 500 ng/L of 17beta-trenbolone (TB), a model AR agonist, and to mixtures of TB with both concentrations of CA. The urine metabolite profile (as measured by 1H NMR spectroscopy) of male FHM exposed to the high concentration of CA was markedly different from that of controls, and this difference was less for males coexposed to the associated TB+CA mixture. The exposure to TB alone had almost no impact on the male urine profile. These results suggest that male FHM urinary metabolite profiling may be useful for directly detecting effects of anti-androgens. In contrast, the urinary profile of male FHM exposed to the lower concentration of CA was not very different from that of controls, but, unexpectedly, this difference was increased when coexposed to the associated TB+CA mixture. This suggests that TB with CA at the lower concentration impacts male FHM through an interactive effect possibly unrelated, or in addition, to AR antagonism. The relative occurrence of male-like nuptial tubercles in female FHM exposed to TB and to the mixtures of TB and CA supported the metabolomics data.

Solid-state C NMR spectroscopy of a C carbonyl-labeled polypeptide

High resolution structural elucidation of macromolecular structure by solid-state nuclear magnetic resonance requires the preparation of uniformly aligned samples that are isotopically labeled. In addition, to use the chemical shift interaction as a high resolution constraint requires an in situ tensor characterization for each site of interest. For (13)C in the peptide backbone, this characterization is complicated by the presence of dipolar coupled (14)N from the peptide bond. Here the (13)C(1)-Gly(2) site in gramicidin A is studied both as a dry powder and in a fully hydrated lipid bilayer environment. Linewidths reported for the oriented samples are a factor of five narrower than those reported elsewhere, and previous misinterpretations of the linewidths are corrected. The observed frequency from oriented samples is shown to be consistent with the recently determined structure for this site in the gramicidin backbone. It is also shown that, whereas a dipolar coupling between (13)C and (14)N is apparent in dry preparations of the polypeptide, in a hydrated bilayer the dipolar coupling is absent, presumably due to a ;self-decoupling' mechanism.

The Arabidopsis family GT43 glycosyltransferases form two functionally nonredundant groups essential for the elongation of glucuronoxylan backbone

There exist four members of family GT43 glycosyltransferases in the Arabidopsis (Arabidopsis thaliana) genome, and mutations of two of them, IRX9 and IRX14, have previously been shown to cause a defect in glucuronoxylan (GX) biosynthesis. However, it is currently unknown whether IRX9 and IRX14 perform the same biochemical function and whether the other two GT43 members are also involved in GX biosynthesis. In this report, we performed comprehensive genetic analysis of the functional roles of the four Arabidopsis GT43 members in GX biosynthesis. The I9H (IRX9 homolog) and I14H (IRX14 homolog) genes were shown to be specifically expressed in cells undergoing secondary wall thickening, and their encoded proteins were targeted to the Golgi, where GX is synthesized. Overexpression of I9H but not IRX14 or I14H rescued the GX defects conferred by the irx9 mutation, whereas overexpression of I14H but not IRX9 or I9H complemented the GX defects caused by the irx14 mutation. Double mutant analyses revealed that I9H functioned redundantly with IRX9 and that I14H was redundant with IRX14 in their functions. In addition, double mutations of IRX9 and IRX14 were shown to cause a loss of secondary wall thickening in fibers and a much more severe reduction in GX amount than their single mutants. Together, these results provide genetic evidence demonstrating that all four Arabidopsis GT43 members are involved in GX biosynthesis and suggest that they form two functionally nonredundant groups essential for the normal elongation of GX backbone.

The poplar GT8E and GT8F glycosyltransferases are functional orthologs of Arabidopsis PARVUS involved in glucuronoxylan biosynthesis

The poplar GT8E and GT8F glycosyltransferases have previously been shown to be associated with wood formation, but their roles in the biosynthesis of wood components are not known. Here, we show that PoGT8E and PoGT8F are expressed in vessels and fibers during wood formation and their encoded proteins are predominantly located in the endoplasmic reticulum. We demonstrate that expression of PoGT8E and PoGT8F in the Arabidopsis parvus mutant rescues the defects in the content and structure of glucuronoxylan conferred by the parvus mutation. These findings suggest that PoGT8E and PoGT8F are involved in glucuronoxylan biosynthesis during wood formation in poplar.

Down-regulation of PoGT47C expression in poplar results in a reduced glucuronoxylan content and an increased wood digestibility by cellulase

Xylan is the second most abundant polysaccharide in dicot wood. Unraveling the biosynthetic pathway of xylan is important not only for our understanding of the process of wood formation but also for our rational engineering of wood for biofuel production. Although several glycosyltransferases are implicated in glucuronoxylan (GX) biosynthesis in Arabidopsis, whether their close orthologs in woody tree species are essential for GX biosynthesis during wood formation has not been investigated. In fact, no studies have been reported to evaluate the effects of alterations in secondary wall-associated glycosyltransferases on wood formation in tree species. In this report, we demonstrate that PoGT47C, a poplar glycosyltransferase belonging to family GT47, is essential for the normal biosynthesis of GX and the normal secondary wall thickening in the wood of the hybrid poplar Populus alba x tremula. RNA interference (RNAi) inhibition of PoGT47C resulted in a drastic reduction in the thickness of secondary walls, a deformation of vessels and a decreased amount of GX in poplar wood. Structural analysis of GX using nuclear magnetic resonance (NMR) spectroscopy demonstrated that the reducing end of GX from poplar wood contains the tetrasaccharide sequence, beta-d-Xylp-(1-->3)-alpha-l-Rhap-(1-->2)-alpha-d-GalpA-(1-->4)-d-Xylp, and that its abundance was significantly decreased in the GX from the wood of the GT47C-RNAi lines. The transgenic wood was found to yield more glucose by cellulase digestion than the wild-type wood, indicating that the GX reduction in wood reduces the recalcitrance of wood to cellulase digestion. Together, these results provide direct evidence demonstrating that the PoGT47C glycosyltransferase is essential for normal GX biosynthesis in poplar wood and that GX modification could improve the digestibility of wood cellulose by cellulase.