Functional Characterization of CsSWEET5a, a Cucumber Hexose Transporter That Mediates the Hexose Supply for Pollen Development and Rescues Male Fertility in Arabidopsis.

Pollen cells require large amounts of sugars from the anther to support their development, which is critical for plant sexual reproduction and crop yield. Sugars Will Eventually be Exported Transporters (SWEETs) have been shown to play an important role in the apoplasmic unloading of sugars from anther tissues into symplasmically isolated developing pollen cells and thereby affect the sugar supply for pollen development. However, among the 17 CsSWEET genes identified in the cucumber (Cucumis sativus L.) genome, the CsSWEET gene involved in this process has not been identified. Here, a member of the SWEET gene family, CsSWEET5a, was identified and characterized. The quantitative real-time PCR and ß-glucuronidase expression analysis revealed that CsSWEET5a is highly expressed in the anthers and pollen cells of male cucumber flowers from the microsporocyte stage (stage 9) to the mature pollen stage (stage 12). Its subcellular localization indicated that the CsSWEET5a protein is localized to the plasma membrane. The heterologous expression assays in yeast demonstrated that CsSWEET5a encodes a hexose transporter that can complement both glucose and fructose transport deficiencies. CsSWEET5a can significantly rescue the pollen viability and fertility of atsweet8 mutant Arabidopsis plants. The possible role of CsSWEET5a in supplying hexose to developing pollen cells via the apoplast is also discussed.

Hexose transporter SWEET5 confers galactose sensitivity to Arabidopsis pollen germination via a galactokinase.

Galactose is an abundant and essential sugar used for the biosynthesis of many macromolecules in different organisms, including plants. Galactose metabolism is tightly and finely controlled, since excess galactose and its derivatives are inhibitory to plant growth. In Arabidopsis (Arabidopsis thaliana), root growth and pollen germination are strongly inhibited by excess galactose. However, the mechanism of galactose-induced inhibition during pollen germination remains obscure. In this study, we characterized a plasma membrane-localized transporter, Arabidopsis Sugars Will Eventually be Exported Transporter 5, that transports glucose and galactose. SWEET5 protein levels started to accumulate at the tricellular stage of pollen development and peaked in mature pollen, before rapidly declining after pollen germinated. SWEET5 levels are responsible for the dosage-dependent sensitivity to galactose, and galactokinase is essential for these inhibitory effects during pollen germination. However, sugar measurement results indicate that galactose flux dynamics and sugar metabolism, rather than the steady-state galactose level, may explain phenotypic differences between sweet5 and Col-0 in galactose inhibition of pollen germination.

Ameliorative effect and mechanism of Yi-Suan-Cha against hyperuricemia in rats.

BACKGROUND: This study aimed to evaluate the urate-lowering effects of Yi-Suan-Cha and explore its underlying mechanisms in experimental hyperuricemia induced in rats. METHODS: Forty-eight male SD rats were randomly allocated into normal control, model, allopurinol, benzbromarone, low-dose Yi-Suan-Cha (0.2 g/ml), and high-dose Yi-Suan-Cha (0.4 g/ml) groups (n = 8 rats per group). Rat models of hyperuricemia were established through intragastric administration of adenine 25 mg/kg + potassium oxalate 300 mg/kg for 3 weeks. After the last administration, serum uric acid, creatinine, and urea nitrogen levels were measured. Renal histopathology was observed by hematoxylin-eosin staining. Xanthine oxidase level in serum and liver homogenates was measured by ELISA. The protein and mRNA expression of URAT1, ABCG2, OAT1, and GLUT9 in the kidney was detected by Western blotting and RT-PCR, respectively. RESULTS: The serum uric acid levels were significantly lowered in all medication groups than in the model group. The benzbromarone and both Yi-Suan-Cha groups showed clear kidney structures with no obvious abnormalities. Compared with the normal control group, the model group showed increased URAT1/GLUT9 protein expression and decreased ABCG2/OAT1 protein expression. Compared with the model group, both Yi-Suan-Cha groups showed decreased URAT1/GLUT9 protein expression and increased ABCG2/OAT1 protein expression. Compared with that in the normal control group, URAT1/GLUT9 mRNA expression increased in the model group. Compared with the model group, the low-dose and high-dose Yi-Suan-Cha groups showed decreased URAT1/GLUT9 mRNA expression and increased ABCG2/OAT1 mRNA expression. CONCLUSION: Yi-Suan-Cha may lower uric acid level by downregulating URAT1/GLUT9 expression and upregulating ABCG2/OAT1 expression.

Transport of UDP-rhamnose by URGT2, URGT4, and URGT6 modulates rhamnogalacturonan-I length.

Rhamnogalacturonan-I biosynthesis occurs in the lumen of the Golgi apparatus, a compartment where UDP-Rhamnose and UDP-Galacturonic Acid are the main substrates for synthesis of the backbone polymer of pectin. Recent studies showed that UDP-Rha is transported from the cytosol into the Golgi apparatus by a family of six UDP-rhamnose/UDP-galactose transporters (URGT1-6). In this study, analysis of adherent and soluble mucilage (SM) of Arabidopsis thaliana seeds revealed distinct roles of URGT2, URGT4, and URGT6 in mucilage biosynthesis. Characterization of SM polymer size showed shorter chains in the urgt2 urgt4 and urgt2 urgt4 urgt6 mutants, suggesting that URGT2 and URGT4 are mainly involved in Rhamnogalacturonan-I (RG-I) elongation. Meanwhile, mutants in urgt6 exhibited changes only in adherent mucilage (AM). Surprisingly, the estimated number of RG-I polymer chains present in urgt2 urgt4 and urgt2 urgt4 urgt6 mutants was higher than in wild-type. Interestingly, the increased number of shorter RG-I chains was accompanied by an increased amount of xylan. In the urgt mutants, expression analysis of other genes involved in mucilage biosynthesis showed some compensation. Studies of mutants of transcription factors regulating mucilage formation indicated that URGT2, URGT4, and URGT6 are likely part of a gene network controlled by these regulators and involved in RG-I synthesis. These results suggest that URGT2, URGT4, and URGT6 play different roles in the biosynthesis of mucilage, and the lack of all three affects the production of shorter RG-I polymers and longer xylan domains.

Lenticular nuclei to thalamic ratio on PET is useful for diagnosis of GLUT1 deficiency syndrome.

PURPOSE: To establish an objective method of [18F]-fluorodeoxyglucose positron emission tomography (FDG-PET) that can assist in the diagnosis of glucose transporter 1 deficiency syndrome (GLUT1-DS). METHODS: FDG-PET was performed in 8 patients with a mean age of 12.5 years (range, 2-22 years) with GLUT1-DS. Their PET findings were compared with those of 45 controls with a mean age of 11.2 years (range, 2-21 years) by statistical parametric mapping (SPM12, Welcome Neurological Institute). The controls had epilepsy of unknown etiology and normal MRI findings. The age-adjusted ratios of mean radioactivities in regions of interest (ROIs) of bilateral lenticular nuclei, thalami, and the whole cerebral cortex were also measured. The sensitivities and specificities of the ratios for the differential diagnosis of GLUT1-DS were also determined. RESULTS: SPM showed significantly decreased uptake in bilateral thalami and increased uptake in bilateral lenticular nuclei in patients with GLUT1-DS. There were no areas in the cerebral cortex with significant differences between patients and controls. On ROI analysis, by setting the cut-off value of the age-adjusted lenticular nuclei/thalami radioactivity ratio to 1.54, patients with GLUT1-DS were differentiated from controls with sensitivity of 1.00 and specificity of 0.98. CONCLUSION: The age-adjusted lenticular nuclei/thalami radioactivity ratio on PET can distinguish patients with GLUT1-DS from patients with epilepsy of unknown etiology with high sensitivity and specificity. It is important to pay attention to the metabolism of the lenticular nuclei and thalami on PET for the diagnosis of GLUT1-DS.

Selection of GmSWEET39 for oil and protein improvement in soybean.

Soybean [Glycine max (L.) Merr.] was domesticated from wild soybean (G. soja Sieb. and Zucc.) and has been further improved as a dual-use seed crop to provide highly valuable oil and protein for food, feed, and industrial applications. However, the underlying genetic and molecular basis remains less understood. Having combined high-confidence bi-parental linkage mapping with high-resolution association analysis based on 631 whole sequenced genomes, we mapped major soybean protein and oil QTLs on chromosome15 to a sugar transporter gene (GmSWEET39). A two-nucleotide CC deletion truncating C-terminus of GmSWEET39 was strongly associated with high seed oil and low seed protein, suggesting its pleiotropic effect on protein and oil content. GmSWEET39 was predominantly expressed in parenchyma and integument of the seed coat, and likely regulates oil and protein accumulation by affecting sugar delivery from maternal seed coat to the filial embryo. We demonstrated that GmSWEET39 has a dual function for both oil and protein improvement and undergoes two different paths of artificial selection. A CC deletion (CC-) haplotype H1 has been intensively selected during domestication and extensively used in soybean improvement worldwide. H1 is fixed in North American soybean cultivars. The protein-favored (CC+) haplotype H3 still undergoes ongoing selection, reflecting its sustainable role for soybean protein improvement. The comprehensive knowledge on the molecular basis underlying the major QTL and GmSWEET39 haplotypes associated with soybean improvement would be valuable to design new strategies for soybean seed quality improvement using molecular breeding and biotechnological approaches.

Exogenous Ketone Supplements Improved Motor Performance in Preclinical Rodent Models.

Nutritional ketosis has been proven effective for neurometabolic conditions and disorders linked to metabolic dysregulation. While inducing nutritional ketosis, ketogenic diet (KD) can improve motor performance in the context of certain disease states, but it is unknown whether exogenous ketone supplements-alternatives to KDs-may have similar effects. Therefore, we investigated the effect of ketone supplements on motor performance, using accelerating rotarod test and on postexercise blood glucose and R-beta-hydroxybutyrate (R-ßHB) levels in rodent models with and without pathology. The effect of KD, butanediol (BD), ketone-ester (KE), ketone-salt (KS), and their combination (KE + KS: KEKS) or mixtures with medium chain triglyceride (MCT) (KE + MCT: KEMCT; KS + MCT: KSMCT) was tested in Sprague-Dawley (SPD) and WAG/Rij (WR) rats and in GLUT-1 Deficiency Syndrome (G1D) mice. Motor performance was enhanced by KEMCT acutely, KE and KS subchronically in SPD rats, by KEKS and KEMCT groups in WR rats, and by KE chronically in G1D mice. We demonstrated that exogenous ketone supplementation improved motor performance to various degrees in rodent models, while effectively elevated R-ßHB and in some cases offsets postexercise blood glucose elevations. Our results suggest that improvement of motor performance varies depending on the strain of rodents, specific ketone formulation, age, and exposure frequency.

CsSWEET1a and CsSWEET17 Mediate Growth and Freezing Tolerance by Promoting Sugar Transport across the Plasma Membrane.

Sugars Will Eventually be Exported Transporters (SWEETs) are important in plant biological processes. Expression levels of CsSWEET1a and CsSWEET17 are induced by cold acclimation (CA) and cold stress in Camellia sinensis. Here, we found that CsSWEET17 was alternatively spliced, and its exclusion (Ex) transcript was associated with the CA process. Both plasma membrane-localized CsSWEET1a and CsSWEET17 transport hexoses, but cytoplasm-localized CsSWEET17-Ex does not. These results indicate that alternative splicing may be involved in regulating the function of SWEET transporters in response to low temperature in plants. The extra C-terminal of CsSWEET17, which is not found in the tonoplast fructose transporter AtSWEET17, did not affect its plasma membrane localization but promoted its sugar transport activities. The overexpression (OE) of CsSWEET1a and CsSWEET17 genes resulted in an increased sugar uptake in Arabidopsis, affecting plant germination and growth. The leaf and seed sizes of the CsSWEET17-OE lines were significantly larger than those of the wild type. Moreover, the OE of CsSWEET1a and CsSWEET17 significantly reduced the relative electrolyte leakage levels under freezing stress. Compared with the wild type, the expression of AtCWINV genes was suppressed in both CsSWEET1a-OE and CsSWEET17-OE lines, indicating the alteration in sugar contents in the cell walls of the OE lines. Furthermore, the interaction between CsSWEET1a and CsSWEET17 was confirmed using yeast two-hybrid and bimolecular fluorescence complementation assays. We showed that CsSWEET1a and CsSWEET17 form homo-/heterodimers in the plasma membrane and mediate the partitioning of sugars between the cytoplasm and the apoplast, thereby regulating plant growth and freezing tolerance.

Epigallocatechin gallate reduces uric acid levels by regulating xanthine oxidase activity and uric acid excretion in vitro and in vivo.

BACKGROUND: This study investigates the effect of epigallocatechin gallate (EGCG) from tea leaves on hyperuricemia and explores the underlying mechanisms in vitro and in vivo. METHODS: The effects of EGCG on proliferation of BRL 3A rat liver cells were evaluated by CCK8 and after stimulation by xanthine the uric acid and xanthine oxidase (XOD) levels were evaluated by a kit; In an in vivo experiment, rats were treated with oxonic acid potassium salt combined with ethylamine pyrimidine to induce high uric acid hematic disease (7 days), The serum uric acid levels and XOD levels were evaluated by a kit, The expressions of OTA1 and GLUT9 were detected by RT-qPCR and Immunohistochemical. RESULTS: EGCG had no effect on proliferation, and significantly reduced serum uric acid levels and inhibited XOD activity (P<0.05). The rat model exhibited a significant rise in blood uric acid levels (54.59 mg/dL), and EGCG significantly reduced the high level of serum uric acid and inhibited XOD activity in the serum and liver tissues (P<0.05). RT-PCR showed that EGCG significantly increased mOAT1 expression in the kidney tissues and reduced mGLUT9 expression (P<0.05). Immunohistochemical results showed that EGCG significantly increased OAT1 expression in the kidney tissues and decreased GLUT9 expression (P<0.05). CONCLUSIONS: These results demonstrate that EGCG has obvious anti-hyperuricemia effects in vitro and in vivo via the inhibition of XOD activity and GLUT9 expression and the promotion of OAT1 expression.

Genome-wide identification and expression analysis of the StSWEET family genes in potato (Solanum tuberosum L.).

BACKGROUND: The sugar will eventually be exported transporter (SWEET) family is a novel type of membrane-embedded sugar transporter that contains seven transmembrane helices with two MtN3/saliva domains. The SWEET family plays crucial roles in multiple processes, including carbohydrate transportation, development, environmental adaptability and host-pathogen interactions. Although SWEET genes, especially those involved in response to biotic stresses, have been extensively characterized in many plants, they have not yet been studied in potato. OBJECTIVE: The identification of StSWEET genes provides important candidates for further functional analysis and lays the foundation for the production of good quality and high yield potatoes through molecular breeding. METHODS: In this study, StSWEET genes were identified using a genome-wide search method. A comprehensive analysis of StSWEET family through bioinformatics methods, such as phylogenetic tree, gene structure and promoter prediction analysis. The expression profiles of StSWEET genes in different potato tissues and under P. infestans attack and sugar stress were studied using quantitative real-time polymerase chain reaction (qRT-PCR). RESULTS: Phylogenetic analysis classified 33 StSWEET genes into four groups containing 12, 5, 12 and 4 genes. Furthermore, the gene structures and conserved motifs found that the StSWEET genes are very conservative during evolution. The chromosomal localization pattern showed that the distribution and density of the StSWEETs on 10 potato chromosomes were uneven and basically clustered. Predictive promoter analysis indicated that StSWEET proteins are associated with cell growth, development, secondary metabolism, and response to biotic and abiotic stresses. Finally, the expression patterns of the StSWEET genes in different tissues and the induction of P. infestans and the process of the sugar stress were investigated to obtain the tissue-specific and stress-responsive candidates. CONCLUSION: This study systematically identifies the SWEET gene family in potato at the genome-wide level, providing important candidates for further functional analysis and contributing to a better understanding of the molecular basis of development and tolerance in potato.

Regulation of pollen lipid body biogenesis by MAP kinases and downstream WRKY transcription factors in Arabidopsis.

Signaling pathways that control the activities in non-photosynthetic plastids, important sites of plant metabolism, are largely unknown. Previously, we demonstrated that WRKY2 and WRKY34 transcription factors play an essential role in pollen development downstream of mitogen-activated protein kinase 3 (MPK3) and MPK6 in Arabidopsis. Here, we report that GLUCOSE-6-PHOSPHATE/PHOSPHATE TRANSLOCATOR 1 (GPT1) is a key target gene of WRKY2/WRKY34. GPT1 transports glucose-6-phosphate (Glc6P) into plastids for starch and/or fatty acid biosynthesis depending on the plant species. Loss of function of WRKY2/WRKY34 results in reduced GPT1 expression, and concomitantly, reduced accumulation of lipid bodies in mature pollen, which leads to compromised pollen viability, germination, pollen tube growth, and male transmission in Arabidopsis. Pollen-specific overexpression of GPT1 rescues the pollen defects of wrky2 wrky34 double mutant. Furthermore, gain-of-function activation of MPK3/MPK6 enhances GPT1 expression; whereas GPT1 expression is reduced in mkk4 mkk5 double mutant. Together, this study revealed a cytoplasmic/nuclear signaling pathway capable of coordinating the metabolic activities in plastids. High-level expression of GPT1 at late stages of pollen development drives Glc6P from cytosol into plastids, where Glc6P is used for fatty acid biosynthesis, an important step of lipid body biogenesis. The accumulation of lipid bodies during pollen maturation is essential to pollen fitness and successful reproduction.

Research on the pharmacodynamics and mechanism of Fraxini Cortex on hyperuricemia based on the regulation of URAT1 and GLUT9.

Fraxini Cortex (also known as Qinpi, QP) has been used for the treatment of hyperuricemia with a significant difference on efficacy of QP from different regions. However, it`s still unknown whether proportion of components is the key and why same kind of herbs have different therapeutic effects. In this study, different sources of QP were collected from Shaanxi Qinpi extracts (SQPE), Henan Qinpi extracts (HQPE), Hebei Qinpi extracts (GQPE) provinces in China. Rat model of hyperuricemia with hypoxanthine combined with potassium oxonate were established to determine the levels of blood urea nitrogen (BUN), serum uric acid (SUA), urine uric acid (UUA) and creatinine (Cr). Hematoxylin-eosin staining (H&E) and Periodic Acid-Schiff staining (PAS) were performed for renal pathology while Western blot analysis and real-time PCR analysis for proteins and mRNA expression levels. High-performance liquid chromatograph (HPLC) was used for components and composition analysis. Our results demonstrated that QPE from different regions could alleviate hyperuricemia via increasing significantly the SCr and BUN levels whereas decreasing markedly UCr, SUA and UUA levels. Additionally, QPE could also improve the pathological changes of the kidneys. The protein and mRNA levels of urate reabsorption transporter 1 (URAT1) and glucose transporter 9 (GLUT9) were down-regulated by QPE treatment. SQPE hold a better activity on improving hyperuricemia and regulating URAT1 and GLUT9. HPLC analysis showed that the proportion of four components aesculin, aesculetin, fraxin, fraxetin were 9.002: 0.350: 8.980: 0.154 (SQPE); 0.526: 0.164: 7.938: 0.102 (HQPE); 12.022: 1.65: 0.878: 1.064 (GQPE). These data indicate that this proportion of effective components may be an important factor for efficacy of QP and had implications for the treatment of hyperuricemia.

[Effect of Chinese herb chicory extract on expression of renal transporter Glut9 in rats with hyperuricemia].

Sixty SD male rats were randomly divided into normal group, model group, benzbromarone group(20 mg•kg⁻¹â€¢d⁻¹), chicory extract high dose, middle dose and low dose groups (5, 7.5, 10 g•kg⁻¹â€¢d⁻¹). The rats in normal group were given with water, and the rats in other groups were given with 10% fructose solution to establish hyperuricemia models. All the rats were sacrificed on the 42th day. Then their serum uric acid(SUA), serum creatinine(CRE), urea nitrogen(BUN) and urinary uric acid(UUA) levels were detected to calculate the clearance rate of uric acid in kidney(CUA). Meanwhile, the protein and gene expression levels of renal glucose transporter family member 9(Glut9) were detected by immunohistochemical and Real-time quantitative reverse transcription-polymerase chain reaction(RT-qPCR) methods. The effects of Chinese herb chicory extract on expression of renal Glut9 and decreasing uric acid were explored in this study, and the results showed that chicory extract could reduce SUA level in rats with hyperuricemia, increase renal CUA, decrease the protein expression of renal Glut9, inhibit uric acid re-absorption in kidney, and thus promote renal uric acid excretion.

The Arabidopsis Golgi-localized GDP-L-fucose transporter is required for plant development.

Nucleotide sugar transport across Golgi membranes is essential for the luminal biosynthesis of glycan structures. Here we identify GDP-fucose transporter 1 (GFT1), an Arabidopsis nucleotide sugar transporter that translocates GDP-L-fucose into the Golgi lumen. Using proteo-liposome-based transport assays, we show that GFT preferentially transports GDP-L-fucose over other nucleotide sugars in vitro, while GFT1-silenced plants are almost devoid of L-fucose in cell wall-derived xyloglucan and rhamnogalacturonan II. Furthermore, these lines display reduced L-fucose content in N-glycan structures accompanied by severe developmental growth defects. We conclude that GFT1 is the major nucleotide sugar transporter for import of GDP-L-fucose into the Golgi and is required for proper plant growth and development.

UDP-galactose transporter gene hUGT1 expression in tobacco plants leads to hyper-galactosylated cell wall components.

We reported previously that tobacco plants transformed with the human UDP-galactose transporter 1 gene (hUGT1-transgenic plants) displayed morphological, architectural, and physiological alterations, such as enhanced growth, increased accumulation of chlorophyll and lignin, and a gibberellin-responsive phenotype. In the present study, we demonstrated that hUGT1 expression altered the monosaccharide composition of cell wall matrix polysaccharides, such as pectic and hemicellulosic polysaccharides, which are biosynthesized in the Golgi lumen. An analysis of the monosaccharide composition of the cell wall matrix polysaccharides revealed that the ratio of galactose to total monosaccharides was significantly elevated in the hemicellulose II and pectin fractions of hUGT1-transgenic plants compared with that of control plants. A hyper-galactosylated xyloglucan structure was detected in hemicellulose II using oligosaccharide mass profiling. These results indicated that, because of the enhanced UDP-galactose transport from the cytosol to the Golgi apparatus by hUGT1, galactose incorporation in the cell wall matrix polysaccharides increased. This increased galactose incorporation may have contributed to increased galactose tolerance in hUGT1-transgenic plants.

Mechanism of proanthocyanidins-induced alcoholic fermentation enhancement in Saccharomyces cerevisiae.

Our previous work revealed proanthocyanidins (PAs) could pose significant enhancement on the activity of H(+)-ATPase and fermentation efficiency after a transient initial inhibition (Li et al in Am J Enol Vitic 62(4):512-518, 2011). The aim of the present work was to understand the possible mechanism for this regulation. At Day 0.5 the gene expression level of PMA1 in AWRI R2 strain supplemented with 1.0 mg/mL PAs was decreased by around 54 % with a 50 % and a 56.5 % increase in the concentration of intracellular ATP and NADH/NAD(+) ratio, respectively, compared to that of control. After the transient adaptation, the gene expression levels of PMA1 and HXT7 in PAs-treated cells were enhanced significantly accompanied by the decrease of ATP contents and NADH/NAD(+) ratio, which resulted in the high level of the activities of rate-limiting enzymes. PAs could pose significant effects on the fermentation via glucose transport, the energy and redox homeostasis as well as the activities of rate-limiting enzymes in glycolysis.

Triheptanoin for glucose transporter type I deficiency (G1D): modulation of human ictogenesis, cerebral metabolic rate, and cognitive indices by a food supplement.

IMPORTANCE: Disorders of brain metabolism are multiform in their mechanisms and manifestations, many of which remain insufficiently understood and are thus similarly treated. Glucose transporter type I deficiency (G1D) is commonly associated with seizures and with electrographic spike-waves. The G1D syndrome has long been attributed to energy (ie, adenosine triphosphate synthetic) failure such as that consequent to tricarboxylic acid (TCA) cycle intermediate depletion. Indeed, glucose and other substrates generate TCAs via anaplerosis. However, TCAs are preserved in murine G1D, rendering energy-failure inferences premature and suggesting a different hypothesis, also grounded on our work, that consumption of alternate TCA precursors is stimulated and may be detrimental. Second, common ketogenic diets lead to a therapeutically counterintuitive reduction in blood glucose available to the G1D brain and prove ineffective in one-third of patients. OBJECTIVE: To identify the most helpful outcomes for treatment evaluation and to uphold (rather than diminish) blood glucose concentration and stimulate the TCA cycle, including anaplerosis, in G1D using the medium-chain, food-grade triglyceride triheptanoin. DESIGN, SETTING, AND PARTICIPANTS: Unsponsored, open-label cases series conducted in an academic setting. Fourteen children and adults with G1D who were not receiving a ketogenic diet were selected on a first-come, first-enrolled basis. INTERVENTION: Supplementation of the regular diet with food-grade triheptanoin. MAIN OUTCOMES AND MEASURES: First, we show that, regardless of electroencephalographic spike-waves, most seizures are rarely visible, such that perceptions by patients or others are inadequate for treatment evaluation. Thus, we used quantitative electroencephalographic, neuropsychological, blood analytical, and magnetic resonance imaging cerebral metabolic rate measurements. RESULTS: One participant (7%) did not manifest spike-waves; however, spike-waves promptly decreased by 70% (P = .001) in the other participants after consumption of triheptanoin. In addition, the neuropsychological performance and cerebral metabolic rate increased in most patients. Eleven patients (78%) had no adverse effects after prolonged use of triheptanoin. Three patients (21%) experienced gastrointestinal symptoms, and 1 (7%) discontinued the use of triheptanoin. CONCLUSIONS AND RELEVANCE: Triheptanoin can favorably influence cardinal aspects of neural function in G1D. In addition, our outcome measures constitute an important framework for the evaluation of therapies for encephalopathies associated with impaired intermediary metabolism.

The Golgi localized bifunctional UDP-rhamnose/UDP-galactose transporter family of Arabidopsis.

Plant cells are surrounded by a cell wall that plays a key role in plant growth, structural integrity, and defense. The cell wall is a complex and diverse structure that is mainly composed of polysaccharides. The majority of noncellulosic cell wall polysaccharides are produced in the Golgi apparatus from nucleotide sugars that are predominantly synthesized in the cytosol. The transport of these nucleotide sugars from the cytosol into the Golgi lumen is a critical process for cell wall biosynthesis and is mediated by a family of nucleotide sugar transporters (NSTs). Numerous studies have sought to characterize substrate-specific transport by NSTs; however, the availability of certain substrates and a lack of robust methods have proven problematic. Consequently, we have developed a novel approach that combines reconstitution of NSTs into liposomes and the subsequent assessment of nucleotide sugar uptake by mass spectrometry. To address the limitation of substrate availability, we also developed a two-step reaction for the enzymatic synthesis of UDP-l-rhamnose (Rha) by expressing the two active domains of the Arabidopsis UDP-l-Rha synthase. The liposome approach and the newly synthesized substrates were used to analyze a clade of Arabidopsis NSTs, resulting in the identification and characterization of six bifunctional UDP-l-Rha/UDP-d-galactose (Gal) transporters (URGTs). Further analysis of loss-of-function and overexpression plants for two of these URGTs supported their roles in the transport of UDP-l-Rha and UDP-d-Gal for matrix polysaccharide biosynthesis.

Phosphorylation of transitory starch by α-glucan, water dikinase during starch turnover affects the surface properties and morphology of starch granules.

Glucan, water dikinase (GWD) is a key enzyme of starch metabolism but the physico-chemical properties of starches isolated from GWD-deficient plants and their implications for starch metabolism have so far not been described. Transgenic Arabidopsis thaliana plants with reduced or no GWD activity were used to investigate the properties of starch granules. In addition, using various in vitro assays, the action of recombinant GWD, ß-amylase, isoamylase and starch synthase 1 on the surface of native starch granules was analysed. The internal structure of granules isolated from GWD mutant plants is unaffected, as thermal stability, allomorph, chain length distribution and density of starch granules were similar to wild-type. However, short glucan chain residues located at the granule surface dominate in starches of transgenic plants and impede GWD activity. A similarly reduced rate of phosphorylation by GWD was also observed in potato tuber starch fractions that differ in the proportion of accessible glucan chain residues at the granule surface. A model is proposed to explain the characteristic morphology of starch granules observed in GWD transgenic plants. The model postulates that the occupancy rate of single glucan chains at the granule surface limits accessibility to starch-related enzymes.

Overexpression of a proton-coupled vacuolar glucose exporter impairs freezing tolerance and seed germination.

Arabidopsis vacuoles harbor, besides sugar transporter of the TMT-type, an early response to dehydration like 6 (ERDL6) protein involved in glucose export into the cytosol. However, the mode of transport of ERDL6 and the plant's feedback to overexpression of its activity on essential properties such as, for example, seed germination or freezing tolerance, remain unexplored. Using patch-clamp studies on vacuoles expressing AtERDL6 we demonstrated directly that this carrier operates as a proton-driven glucose exporter. Overexpression of BvIMP, the closest sugar beet (Beta vulgaris) homolog to AtERDL6, in Arabidopsis leads surprisingly to impaired seed germination under both conditions, sugar application and low environmental temperatures, but not under standard conditions. Upon cold treatment, BvIMP overexpressor plants accumulated lower quantities of monosaccharides than the wild-type, a response in line with the reduced frost tolerance of the transgenic Arabidopsis plants, and the fact that cold temperatures inhibits BvIMP transcription in sugar beet leaves. With these findings we show that the tight control of vacuolar sugar import and export is a key requisite for cold tolerance and seed germination of plants.