Gly Levels Research Articles

Targeting the hedgehog signal transduction pathway at the level of GLI inhibits neuroblastoma cell growth in vitro and in vivo

Hedgehog (HH) signaling is an important regulator of embryogenesis that has been associated with the development of several types of cancer. HH signaling is characterized by Smoothened (SMO)-dependent activation of the GLI transcription factors, which regulate the expression of critical developmental genes. Neuroblastoma, an embryonal tumor of the sympathetic nervous system, was recently shown to express high levels of key molecules in this signaling cascade. Using compounds blocking SMO (cyclopamine and SANT1) or GLI1/GLI2 (GANT61) activity revealed that inhibition of HH signaling at the level of GLI was most effective in reducing neuroblastoma growth. GANT61 sensitivity positively correlated to GLI1 and negatively to MYCN expression in the neuroblastoma cell lines tested. GANT61 downregulated GLI1, c-MYC, MYCN and Cyclin D1 expression and induced apoptosis of neuroblastoma cells. The effects produced by GANT61 were mimicked by GLI knockdown but not by SMO knockdown. Furthermore, GANT61 enhanced the effects of chemotherapeutic drugs used in the treatment of neuroblastoma in an additive or synergistic manner and reduced the growth of established neuroblastoma xenografts in nude mice. Taken together this study suggests that inhibition of HH signaling is a highly relevant therapeutic target for high-risk neuroblastoma lacking MYCN amplification and should be considered for clinical testing.

Downregulation of the δ-Subunit Reduces Mitochondrial ATP Synthase Levels, Alters Respiration, and Restricts Growth and Gametophyte Development in Arabidopsis

The mitochondrial ATP synthase (F(1)F(o) complex) is an evolutionary conserved multimeric protein complex that synthesizes the main bulk of cytosolic ATP, but the regulatory mechanisms of the subunits are only poorly understood in plants. In yeast, the δ-subunit links the membrane-embedded F(o) part to the matrix-facing central stalk of F(1). We used genetic interference and an inhibitor to investigate the molecular function and physiological impact of the δ-subunit in Arabidopsis thaliana. Delta mutants displayed both male and female gametophyte defects. RNA interference of delta resulted in growth retardation, reduced ATP synthase amounts, and increased alternative oxidase capacity and led to specific long-term increases in Ala and Gly levels. By contrast, inhibition of the complex using oligomycin triggered broad metabolic changes, affecting glycolysis and the tricarboxylic acid cycle, and led to a successive induction of transcripts for alternative respiratory pathways and for redox and biotic stress-related transcription factors. We conclude that (1) the δ-subunit is essential for male gametophyte development in Arabidopsis, (2) a disturbance of the ATP synthase appears to lead to an early transition phase and a long-term metabolic steady state, and (3) the observed long-term adjustments in mitochondrial metabolism are linked to reduced growth and deficiencies in gametophyte development.

Measurement of glycine in gray and white matter in the human brain in vivo by 1H MRS at 7.0 T

The concentration of glycine (Gly) was measured in gray matter (GM) and white matter (WM) in the human brain using single-voxel localized (1)H MRS at 7 T. A point-resolved spectroscopy sequence with echo time = 150 ms was used for measuring Gly levels in various regions of the frontal and occipital lobes in 11 healthy volunteers and one subject with a glioblastoma. The point-resolved spectroscopy spectra were analyzed with LCModel using basis functions generated from density matrix simulations that included the effects of volume localized radio-frequency and gradient pulses. The fraction of GM and white matter within the voxels was obtained from T(1)-weighted image segmentation. The metabolite concentrations within the voxels, estimated with respect to the GM + WM water concentrations, were fitted to a linear function of fractional GM content. The Gly concentrations in pure GM and white matter were estimated to be 1.1 and 0.1 mM, with 95% confidence intervals 1.0-1.2 and 0.0-0.2, respectively.

Angiotensin converting enzyme (ACE) inhibitory, antihypertensive and antihyperlipidaemic activities of protein hydrolysates from Rhopilema esculentum

Angiotensin-converting enzyme (ACE) inhibitory, antihypertensive and antihyperlipidaemic activities of protein hydrolysates (RPH) from the jellyfish Rhopilema esculentum were investigated. R. esculentum was hydrolysed sequentially with pepsin and papain, and then the hydrolysate was ultrafiltered with a 2000 Da cut-off membrane. It was found that RPH contained high levels of Gly, Glu, Pro, Asp and Ala, having potential ACE inhibitory activity in vitro with an IC(50) of 1.28 mg/ml. It was also found that systolic blood pressure was reduced markedly in spontaneously hypertensive rats after single and chronic oral administration of RPH, indicating that RPH had an antihypertensive effect. In addition, oral administration of RPH decreased total serum cholesterol and triglyceride, and increased high-density lipoprotein cholesterol in rats fed with high-fat diet. These results indicate that RPH may prove to be a promising functional food for the prevention and treatment of hypertension and hyperlipidaemia.

Determination of the arginine, tryptophan, and glycine ideal-protein ratios in high-yield broiler chicks

SUMMARY In formulation, essential or semiessential and potentially limiting amino acids, such as Arg, Trp, and Gly, can sometimes be ignored and no minimum nutrient value assigned to these. Further, data estimating their dietary needs relative to dietary Lys are sparse and, in some cases, need formal revalidation. For that purpose, these 3 amino acids (Arg, Trp, Gly) were studied individually using Ross × Ross 708 chicks reared in a sex-separate manner and given progressive amounts of either Arg, Trp, or Gly relative to Lys. Birds were fed the diets from 0 to 18 d posthatch, and their BW and feed consumption were measured at 18 d of age. A blood sample was taken from birds from each experimental unit during all 3 studies and analyzed for certain blood plasma metabolites to further evaluate the nutritional status of these chicks. Sex did not interact with diet for any of the amino acids studied, so regression analysis was performed using all the experimental units averaged across sexes, thus resembling straight-run flocks. The Arg:Lys ratio was found to be optimized between 106 and 114%, depending on the response parameter. Furthermore, livability was seriously compromised with lower Arg:Lys treatments, but any deleterious effect was dissipated when a minimum of 103% of dietary Arg:Lys was fed to the chicks. Dietary Trp was found to be adequate between 17 and 19% of dietary Lys, whereas (Gly + Ser):Lys was calculated to be adequate at a ratio of 161% for BW gain. Feed conversion was observed to improve linearly up to the highest level of (Gly + Ser):Lys fed. Therefore, Gly + Ser needs may be elevated because of the possible inefficient biosynthesis of Gly by the chick, and this should be the focus of future research.

Abstract 17495: Thrombospondin-1/CD36 Pathway Critically Contributes to SHH Signaling Defect and EPC Dysfunction on Wound Healing in Type 1 Diabetes

Introduction: Refractory wounds in diabetic patients is a significant clinical problem. We reported previously that sonic hedgehog (SHH), a morphogenic protein central to wound repair, is deficient in diabetes, but the underlying mechanisms are poorly understood. We hypothesized that thrombospondin-1 (TSP-1) through its receptor CD36 contributes to SHH signaling defect in cutaneous tissue and endothelial progenitor cells (EPCs), resulting in impaired wound healing in type 1 diabetic mice. Methods and Results: Cutaneous expression of SHH and its signaling molecules including Patched (Ptc), Smoothened (Smo), and Gli were significantly decreased in streptozotocin (STZ)-induced type 1 diabetic mice (male, C57BL/6J, 12 weeks) vs. their age-matched control littermates (Western blot analysis, n=5, p<0.05 vs. control), which were reversed in STZ-treated TSP-1 -/- mice (homozygote, C57BL/6J background, n=5, p<0.05 vs. STZ-treated WT mice). Excisional wound (6-mm punch biopsy) closure was significantly delayed in STZ mice (n=6, p<0.05 vs. control) with reduced wound blood flow (Laser Doppler), which was not observed in STZ-treated TSP-1 -/- mice (n=5, p<0.05 vs. STZ-treated WT mice). The protective effect of TSP-1 depletion on wound repair was abolished following topical treatment with the selective SHH inhibitor cyclopamine (5 μ M, 30 min/day, n=5, p<0.05 vs. STZ-treated TSP-1 -/- mice). Isolated EPCs from bone marrow of STZ mice showed significantly impaired angiogenesis (Matrigel tube formation, n=4, p<0.05 vs. control), which was rescued by exogenous SHH (1 mg/L, 24 hours, n=4, p<0.05 vs. STZ-control). Increased EPC angiogenesis in STZ-treated TSP-1 -/- mice (n=5, p<0.05 vs. STZ-WT) was inhibited by the selective SHH inhibitor cyclopamine (5 μ M, 24 hours, n=5, p<0.05). SHH, Ptc, Smo and Gli levels were significantly increased in EPCs from TSP-1 -/- mice and CD36 -/- mice, but not CD47 -/- mice (n=6, p<0.05 vs. WT). Normal EPCs treated with recombinant human TSP-1 protein (2.2 nM, 24 hour) exhibited impaired angiogenesis, an effect that was not observed in EPCs from CD36 -/- mice (n=5, p<0.05). Conclusion: TSP-1/CD36 pathway critically contributes to SHH signaling defect, resulting in EPC dysfunction and impaired wound healing in type 1 diabetic mice.

The Antagonistic Action of B56-containing Protein Phosphatase 2As and Casein Kinase 2 Controls the Phosphorylation and Gli Turnover Function of Daz Interacting Protein 1

The Hedgehog (Hh) pathway is evolutionarily conserved and plays critical roles during embryonic development and adult tissue homeostasis. Defective Hh signaling has been linked to a wide range of birth defects and cancers. Hh family proteins regulate the expression of their downstream target genes through the control of proteolytic processing and the transcriptional activation function of Gli transcription factors. Although Hh-dependent regulation of Gli has been studied extensively, other Gli regulatory mechanisms remain relatively unappreciated. Here we report our identification of a novel signaling cascade that controls the stability of Gli proteins. This cascade consists of Daz interacting protein 1 (Dzip1), casein kinase 2 (CK2), and B56 containing protein phosphatase 2As (PP2As). We provide evidence that Dzip1 is involved in a novel Gli turnover pathway. We show that CK2 directly phosphorylates Dzip1 at four serine residues, Ser-664/665/706/714. B56-containing PP2As, through binding to a domain located between amino acid residue 474 and 550 of Dzip1, dephosphorylate Dzip1 on these CK2 sites. Our mutagenesis analysis further demonstrates that the unphosphorylatable form of Dzip1 is more potent in promoting Gli turnover. Consistently, we found that the stability of Gli proteins was decreased upon CK2 inhibition and increased by inhibition of B56-containing PP2As. Thus, reversible phosphorylation of Dzip1, which is controlled by the antagonistic action of CK2 and B56-containing PP2As, has an important impact on the stability of Gli transcription factors and Hh signaling.

Teores de glicina+ serina total em dietas de baixa proteína bruta para de frangos de corte de 22 a 35 dias de idade

O experimento foi realizado em delineamento inteiramente ao acaso para avaliar os efeitos de diferentes teores de glicina + serina (gli+ser) total em dietas de baixa proteína bruta (PB) sobre o desempenho e as características de carcaça de frangos de corte de 22 a 35 dias de idade. Foram utilizadas 750 aves distribuídas em cinco tratamentos, cinco repetições e 30 aves por unidade experimental. As aves foram alimentadas até os 21 dias com uma dieta comum de acordo com as exigências. A partir do 21º dia, as dietas utilizadas continham 17% de PB e níveis de gli+ser de 1,50; 1,75; 2,00 e 2,25%; a dieta-controle continha 21% de PB. O teor de gli+ser teve efeito linear sobre a conversão alimentar e não sobre as demais variáveis de desempenho. Não houve efeito de tratamento sobre os rendimentos de carcaça e cortes. Houve efeito linear decrescente do teor de gli+ser sobre a matéria seca da carcaça.

Abstract SY05-01: Biological and clinical activities of FDA-approved drugs that antagonize Hh signaling

Abstract The inappropriate activity of the Hedeghog (Hh) signaling pathway noted in a variety of tumor types has prompted efforts to develop small molecule antagonists of Hh pathway signaling. The use of FDA-approved drugs as Hh pathway antagonists may avoid some of the expense and delay associated with de novo development of Hh pathway antagonists. We have identified two FDA-approved drugs, itraconazole and arsenic trioxide, as potent inhibitors of the Hh pathway in vitro and in vivo at the level of Smoothened (Smo) and Gli, respectively. In addition, both itraconazole and arsenic trioxide have inhibitory activity against a mutant Smoothened resistant to GDC-0449, a potent Smo antagonist. These preclinical studies have led to a pilot clinical trial (ID: NCT01108094) using itraconazole for patients with basal cell carcinoma, a skin tumor that is driven by the Hh pathway. We have treated 13 subjects with 200mg of itraconazole twice daily and found -32% (95% CI: -19 to -42%) reduction in tumor diameter in 1 month. These studies suggest that FDA-approved drugs show promise as Hh pathway antagonists for the treatment of Hh-dependent cancers and warrant further study. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr SY05-01. doi:10.1158/1538-7445.AM2011-SY05-01

Plasma amino acid profile is altered by visceral fat accumulation and is a predictor of visceral obesity in humans

Abstract Background: The plasma amino acid profile can be a useful indicator in clinical settings because it changes in response to various metabolic alternations. However, the association between the plasma amino acid profile and body fat accumulation has not been evaluated in humans. Objective: This study aimed to relate plasma amino acids to visceral fat accumulation in humans because excess visceral fat raises the odds ratio of developing metabolic syndrome. Design: A total of 1,449 subjects (985 males and 464 females) who had undergone a comprehensive health screening were enrolled in this study. The visceral fat area (VFA) was determined in each subject using CT imaging. Subjects were then divided into two groups according to VFA: high-VFA (&8805;100 cm2, n=867) and low-VFA (<100 cm2, n=582). The plasma amino acid profile was analyzed together with other metabolic valuables and then compared between the two groups using uni- and multivariate analyses. Results: As the degree of visceral fat accumulation increased, plasma concentrations of several amino acids changed significantly. Glu, Val, Leu, Ile, Tyr, Ala, Phe, Pro, Lys, Orn, Trp, Met, His and alpha-aminobutyric acid (ABA) levels were significantly higher in the high-VFA group compared to the low-VFA group, whereas the levels of Gly, Ser, Gln and Asn were significantly lower. To evaluate the potential of using amino acids as an indicator of VFA, a discriminant analysis was conducted with the multivariate logistic regression analysis "AminoIndex", and the ROC curve was calculated. The resulting "AminoIndex" exhibited an area under the ROC curve of 0.81 (95% confidence interval; 0.78 to 0.83), with higher sensitivity and specificity by 80% and 65%, respectively. Conclusions: The plasma amino acid profile changes depending on visceral fat content and can be used as a marker for diagnosing elevated visceral obesity in humans.

Analysis of amino acid neurotransmitters in hypothalamus of rats during cerebral ischemia–reperfusion by microdialysis and capillary electrophoresis

In this work, focal cerebral ischemia and reperfusion were induced by the model of middle cerebral artery occlusion. The dialysate of extracellular fluid in the hypothalamus of rats were obtained by using brain microdialysis technique. An efficient and sensitive MEKC method for the simultaneous determination of multiple amino acid neurotransmitters in microdialysate was developed by capillary electrophoresis with laser-induced fluorescence detection and 5-(4, 6-dichloro-s-triazin-2-ylamino) fluorescein derivatization. Different parameters that influenced derivatization reaction and CE separation were studied and optimized. This method was used to investigate the dynamic change of fourteen amino acid neurotransmitters in microdialysates during cerebral ischemia/reperfusion period. Our results reveal that MCAO and reperfusion elicited significant increases in the extracellular levels of Arg, Lys, Trp, Phe, Gln, GABA, Asn, Pro, Ser, Ala, Tau, Gly, Glu and Asp. The excitatory/inhibitory neurotransmitter balance was disturbed during ischemia/reperfusion. The dynamic changes and functional status of releasable neurotransmitters during ischemia/reperfusion were discussed.

Antihepatotoxic Effect of Feronia Limonia Fruit against Carbon Tetrachloride Induced Hepatic Damage in Albino Rats

Feronia limonia Swingle, though mentioned as a high utility medicinal plant in Ayurveda for the treat-ment of liver disorders, but has no scientific investigations. Therefore, the present study was undertaken to investigate the hepatoprotective activity of extracts of Feronia limonia fruit on albino rat liver, damage induced by single dose of carbon-tetrachloride (1.5 ml/kg, p.o.). The oral administration of extracts (500 mg/kg, p.o.) for 7 days has shown significant hepatoprotective action. There is reduction in the elevated levels of serum enzymes such SGOT, SGPT, ALP and Serum bilirubin and elevation in level of GSH, GPX,GLY and total protein in Feronia limonia protected rats.

High-resolution magic angle spinning magnetic resonance spectroscopy detects glycine as a biomarker in brain tumors

The non-essential amino acid neurotransmitter glycine (Gly) may serve as a biomarker for brain tumors. Using 36 biopsies from patients with brain tumors [12 glioblastoma multiforme (GBM); 10 low-grade (LG), including 7 schwannoma and 3 pylocytic astrocytoma; 7 meningioma (MN); 7 brain metastases (MT), including 3 adenocarcinoma and 4 breast cancer] and 9 control biopsies from patients undergoing surgery for epilepsy, we tested the hypothesis that the presence of glycine may distinguish among these brain tumor types. Using high-resolution magic angle spinning (HRMAS) 1H magnetic resonance spectroscopy (MRS), we determined a theoretically optimum echo time (TE) of 50 ms for distinguishing Gly signals from overlapping myo-inositol (Myo) signals and tested our methodology in phantom and biopsy specimens. Quantitative analysis revealed higher levels of Gly in tumor biopsies (all combined) relative to controls; Gly levels were significantly elevated in LG, MT and GBM biopsies (P≤0.05). Residual Myo levels were elevated in LG and MT and reduced in MN and GBM (P<0.05 vs. control levels). We observed higher levels of Gly in GBM as compared to LG tumors (P=0.05). Meanwhile, although Gly levels in GBM and MT did not differ significantly from each other, the Gly:Myo ratio did distinguish GBM from MT (P<0.003) and from all other groups, a distinction that has not been adequately made previously. We conclude from these findings that Gly can serve as a biomarker for brain tumors and that the Gly:Myo ratio may be a useful index for brain tumor classification.

Increased plasma levels of the mature and intermediate forms of adrenomedullin in obesity

Adrenomedullin (AM) is a cardiovascular protective peptide produced in various organs and tissues including adipose tissue. In the present study, we measured the plasma AM levels of subjects with or without obesity by two assay methods to separately evaluate the biologically active AM–NH 2 and the intermediate form of AM–glycine (AM–Gly). We measured the total AM and AM–NH 2 levels of plasma in 52 obese and 172 non-obese residents of a Japanese community, who received regular health check-ups and had no overt cardiovascular disease. AM–Gly values were obtained by subtracting AM–NH 2 levels from those of total AM. Both the AM–NH 2 and AM–Gly levels of the subjects with obesity were higher than those without obesity, and significant relationships were noted between body mass index (BMI) and the plasma levels of the two molecular forms of AM in a simple regression analysis. Moreover, the significant factors identified by multivariate analyses were BMI and serum triglyceride for AM–NH 2 and diastolic blood pressure, insulin, high-density lipoprotein-cholesterol, and plasma renin activity for AM–Gly. These results suggest active roles for the two molecular forms of AM in metabolic disorders associated with obesity in subjects without overt cardiovascular disease.

Dietary glycine and threonine interactive effects in broilers

Little information is available regarding the interaction of dietary Thr and Gly on the potential metabolic sparing effects, live production, or breast meat yield of broilers. To test these potential interactions, 432 one-day-old Ross 308 male broilers were fed a common diet up to 21 d of age, and then fed 1 of 6 experimental diets. A factorial arrangement of treatments consisted of 3 dietary levels of standardized digestible Thr (0.57, 0.61, and 0.65%) in combination with 2 levels of total Gly + Ser (1.55 and 1.65%). Experimental diets were fed from 21 to 42 d of age, with live performance, carcass traits, and free blood plasma levels of Gly, Ser, and Thr serving as evaluation criteria. Interactions (P ≤ 0.05) were observed for BW gain, feed consumption, carcass and breast meat weight, and carcass yield, all showing improvements with increasing dietary Thr in combination with low dietary Gly + Ser treatments. Circulating plasma Gly, Ser, and Thr were affected by their respective dietary status.

Mutation in MTO1 involved in tRNA modification impairs mitochondrial RNA metabolism in the yeast Saccharomyces cerevisiae

The yeast MTO1 gene encodes an evolutionarily conserved protein for the biosynthesis of the 5-carboxymethylaminomethyl group of cmnm 5s 2U in the wobble position of mitochondrial tRNA. However, mto1 null mutant expressed the respiratory deficient phenotype only when coupled with the C1409G mutation of mitochondrial 15S rRNA. To further understand the role of MTO1 in mitochondrial RNA metabolism, the yeast mto1 null mutants carrying either wild-type (P S) or 15S rRNA C1409G allele (P R) have been characterized by examining the steady-state levels, aminoacylation capacity of mitochondrial tRNA, mitochondrial gene expression and petite formation. The steady-state levels of tRNA Lys, tRNA Glu, tRNA Gln, tRNA Leu, tRNA Gly, tRNA Arg and tRNA Phe were decreased significantly while those of tRNA Met and tRNA His were not affected in the mto1 strains carrying the P S allele. Strikingly, the combination of the mto1 and C1409G mutations gave rise to the synthetic phenotype for some of the tRNAs, especially in tRNA Lys, tRNA Met and tRNA Phe. Furthermore, the mto1 strains exhibited a marked reduction in the aminoacylation levels of mitochondrial tRNA Lys, tRNA Leu, tRNA Arg but almost no effect in those of tRNA His. In addition, the steady-state levels of mitochondrial COX1, COX2, COX3, ATP6 and ATP9 mRNA were markedly decreased in mto1 strains. These data strongly indicate that unmodified tRNA caused by the deletion of MTO1 gene caused the instability of mitochondrial tRNAs and mRNAs and an impairment of aminoacylation of mitochondrial tRNAs. Consequently, the deletion of MTO1 gene acts in synergy with the 15S rRNA C1409G mutation, leading to the loss of COX1 synthesis and subsequent respiratory deficient phenotype.

EFFECT OF OLIVE OIL AND GLYCEROL ON PHYSICAL PROPERTIES OF WHEY PROTEIN CONCENTRATE FILMS

ABSTRACT Olive oil was incorporated into whey protein through emulsification to produce films. Whey protein films were prepared by dispersing 10% protein in distilled water; and plasticized with different levels of glycerol (glycerol : protein [Gly : pro ] = 0.5 and 0.6). Olive oil was added at different levels (oil : pro = 0.0, 0.2, 0.3 and 0.4). The emulsion films were evaluated for mechanical properties, water vapor permeability (WVP) and opacity. Increasing the levels of Gly or olive oil in the films led to decreases in modulus and tensile strength. Increasing Gly content of films at oil/pro ratios of 0.2, 0.4 led to slight increases in elongation (EL). Increasing the oil : pro ratio further resulted in a decrease in EL for all films. No significant difference in WVP and opacity was observed between films made from mixtures of various proportions of whey protein concentrate–Gly with increasing olive oil (addition) at all levels of the plasticizer.PRACTICAL APPLICATIONSThe main advantages of using edible films are extending food shelf life, improving food quality, adding value to the edible film‐forming polymer and reducing synthetic packaging materials. Whey, obtained as a by‐product in cheese, is produced in large quantities and has excellent functional properties and could potentially be used for edible films.

Pharmacological stimulation of NMDA receptors via co-agonist site suppresses fMRI response to phencyclidine in the rat

Increasing experimental evidence suggests that impaired N-methyl-D: -aspartic acid (NMDA) receptor (NMDAr) function could be a key pathophysiological determinant of schizophrenia. Agonists at the allosteric glycine (Gly) binding site of the NMDA complex can promote NMDAr activity, a strategy that could provide therapeutic efficacy for the disorder. NMDAr antagonists like phencyclidine (PCP) can induce psychotic and dissociative symptoms similar to those observed in schizophrenia and are therefore widely used experimentally to impair NMDA neurotransmission in vivo. In the present study, we used pharmacological magnetic resonance imaging (phMRI) to investigate the modulatory effects of endogenous and exogenous agonists at the NMDAr Gly site on the spatiotemporal patterns of brain activation induced by acute PCP challenge in the rat. The drugs investigated were D: -serine, an endogenous agonist of the NMDAr Gly site, and SSR504734, a potent Gly transporter type 1 (GlyT-1) inhibitor that can potentiate NMDAr function by increasing synaptic levels of Gly. Acute administration of PCP induced robust and sustained activation of discrete cortico-limbo-thalamic circuits. Pretreatment with D: -serine (1 g/kg) or SSR504734 (10 mg/kg) completely inhibited PCP-induced functional activation. This effect was accompanied by weak but sustained deactivation particularly in cortical areas. These findings suggest that agents that stimulate NMDAr via Gly co-agonist site can potentiate NMDAr activity in the living brain and corroborate the potential for this class of drugs to provide selective enhancement of NMDAr neurotransmission in schizophrenia.

Arabidopsis 10-formyl tetrahydrofolate deformylases are essential for photorespiration.

In prokaryotes, PurU (10-formyl tetrahydrofolate [THF] deformylase) metabolizes 10-formyl THF to formate and THF for purine and Gly biosyntheses. The Arabidopsis thaliana genome contains two putative purU genes, At4g17360 and At5g47435. Knocking out these genes simultaneously results in plants that are smaller and paler than the wild type. These double knockout (dKO) mutant plants show a 70-fold increase in Gly levels and accumulate elevated levels of 5- and 10-formyl THF. Embryo development in dKO mutants arrests between heart and early bent cotyledon stages. Mature seeds are shriveled, accumulate low amounts of lipids, and fail to germinate. However, the dKO mutant is only conditionally lethal and is rescued by growth under nonphotorespiratory conditions. In addition, culturing dKO siliques in the presence of sucrose restores normal embryo development and seed viability, suggesting that the seed and embryo development phenotypes are a result of a maternal effect. Our findings are consistent with the involvement of At4g17360 and At5g47435 proteins in photorespiration, which is to prevent excessive accumulation of 5-formyl THF, a potent inhibitor of the Gly decarboxylase/Ser hydroxymethyltransferase complex. Supporting this role, deletion of the At2g38660 gene that encodes the bifunctional 5,10-methylene THF dehydrogenase/5,10-methenyl THF cyclohydrolase that acts upstream of 5-formyl THF formation restored the wild-type phenotype in dKO plants.

Nutritional and Physiological Effects of Dietary Sinapic Acid (4-Hydroxy-3,5-Dimethoxy-Cinnamic Acid) in Broiler Chickens and its Metabolism in the Digestive Tract

Sinapic acid (SA) is a major free phenolic acid in rapeseed meal, with the majority found in the esterified form of sinapine. Two experiments were conducted to delineate the effect of dietary SA on broiler chickens, in terms of performance, toxicity, and nutrient digestibility. In the first experiment, 80 male broiler chicks were randomly assigned to 5 diets adequate in all nutrients and containing 0, 0.05, 0.10, 0.15, or 0.20% dietary SA. Performance from 0 to 18 d of age and the relative size of all the internal organs and intestines were not affected (all P>0.05) by dietary treatment. In addition, dietary SA had no effect (P>0.05) on the serum activity of creatine kinase and lactate dehydrogenase, which indicated that there was no damage to skeletal muscle, heart muscle, liver, kidneys, or brain. The objectives of the second experiment were to investigate the effect of SA on nutrient retention and to study the retention of SA in the digestive tract. Male broiler chicks (96) were randomly assigned into 4 treatments containing dietary SA at 0, 0.025, 0.05, and 0.10%. Dietary SA at the 0.025% level increased feed intake compared with control (P<0.05). Regression analysis indicated a quadratic response for both weight gain and feed intake (P<0.05) as SA increased in the diet. Again, dietary SA did not affect the relative weights of bursa of Fabricius, liver, kidney, or digestive tract. Nitrogen-corrected AME and protein digestibility were not affected by SA level. A negative linear relationship was found between dietary SA level and apparent ileal digestibility of Met, Thr, Ser, Pro, Gly, Ala, and Phe. Sinapic acid disappearance in the ileum was above 97% for all SA levels, whereas apparent SA retention in excreta ranged from 64 to 79%. Sinapic acid at dietary levels investigated in this research is apparently not toxic to broiler chickens but may have a negative effect on amino acid digestibility at higher levels.