bluuebunny/crossref_metadata_2025 huggingface dataset:
Difficidin and bacilysin from Bacillus amyloliquefaciens FZB42 have antibacterial activity against Xanthomonas oryzae rice pathogens
Authors: Wu Liming , Wu Huijun , Chen Lina , Yu Xinfang , Borriss Rainer , Gao Xuewen
Published: August 2015

Bacterial blight and bacterial leaf streak are serious, economically damaging, diseases of rice caused by the bacteria Xanthomonas oryzae pv. oryzae and X. oryzae pv. oryzicola. Bacillus amyloliquefaciens FZB42 was shown to possess biocontrol activity against these Xanthomonas strains by producing the antibiotic compounds difficidin and bacilysin. Analyses using fluorescence, scanning electron and transmission electron microscopy revealed difficidin and bacilysin caused changes in the cell wall and structure of Xanthomonas. Biological control experiments on rice plants demonstrated the ability of difficidin and bacilysin to suppress disease. Difficidin and bacilysin caused downregulated expression of genes involved in Xanthomonas virulence, cell division and protein and cell wall synthesis. Taken together, our results highlight the potential of B. amyloliquefaciens FZB42 as a biocontrol agent against bacterial diseases of rice and the utility of difficidin and bacilysin as antimicrobial compounds.
A start codon mutation of the FRMD7 gene in two Korean families with idiopathic infantile nystagmus
Authors: Choi Jae-Hwan , Shin Jin-Hong , Seo Je Hyun , Jung Jae-Ho , Choi Kwang-Dong
Published: August 2015

Idiopathic infantile nystagmus (IIN) is the involuntary oscillation of the eyes with onset in the first few months of life. The most common form of inheritance is X-linked and mutations in FRMD7 gene are a major cause. To identify the FRMD7 gene mutations associated with X-linked IIN, we performed PCR-based DNA direct sequencing in 4 affected subjects from 2 Korean families. We also assessed structural abnormalities of retina and optic nerve head using optical coherence tomography (OCT). Genetic analysis revealed a A>G transversion at nucleotide c.1, the first base of the start codon. This mutation leads to the loss of the primary start codon ATG for methionine, which is replaced by a triplet GTG for valine. The alternative in-frame start codon is not present around a mutation. OCT revealed the morphological changes within the optic nerve head, including shallow cup depth and small cup-to-disc ratio. In summary, we identified a novel start codon mutation within the FRMD7 gene of 2 Korean families. Our data expands the mutation spectrum of FRMD7 causing IIN. We also demonstrated abnormal developments of afferent system in patients with FRMD7 mutations using OCT, which may help to understand the etiological factor in development of nystagmus.
Improve oxidation resistance at high temperature by nanocrystalline surface layer
Authors: Xia Z. X. , Zhang C. , Huang X. F. , Liu W. B. , Yang Z. G.
Published: August 2015

An interesting change of scale sequence occurred during oxidation of nanocrystalline surface layer by means of a surface mechanical attrition treatment. The three-layer oxide structure from the surface towards the matrix is Fe3O4, spinel FeCr2O4 and corundum (Fe,Cr)2O3, which is different from the typical two-layer scale consisted of an Fe3O4 outer layer and an FeCr2O4 inner layer in conventional P91 steel. The diffusivity of Cr, Fe and O is enhanced concurrently in the nanocrystalline surface layer, which causes the fast oxidation in the initial oxidation stage. The formation of (Fe,Cr)2O3 inner layer would inhabit fast diffusion of alloy elements in the nanocrystalline surface layer of P91 steel in the later oxidation stage and it causes a decrease in the parabolic oxidation rate compared with conventional specimens. This study provides a novel approach to improve the oxidation resistance of heat resistant steel without changing its Cr content.
Spatial correlations and optical properties in three-dimensional deterministic aperiodic structures
Authors: Renner Michael , Freymann Georg von
Published: August 2015

Photonic systems have strongly varying optical properties depending on the spatial correlations present in a given realization. In photonic crystals the correlations are spatially periodic forming Bravais lattices whereas the building blocks of an amorphous medium are randomly distributed without any long-range order. In this manuscript we study the optical properties of so-called deterministic aperiodic structures which fill the gap between the aforementioned two limiting cases. Within this group we vary the spectrum of the spatial correlations from being pure-point over singularly-continuous to absolutely-continuous. The desired correlations are created in direct-laser written three-dimensional polymer structures using one construction principle which allows us to attribute the optical behaviour solely to the encoded spectrum. Infrared reflection measurements reveal the characteristic response of each spectral type verifying the successful fabrication of large deterministic aperiodic structures. To prove the presence of the correlations in all directions we perform transmission experiments parallel to the substrate by means of micro-optical mirrors placed next to the structures. Transport measurements reveal a strong dependence of the effective beam width at the output facet on the encoded lattice type. Finally, we reproduce the lattice type dependent transport behavior in numerical calculations ruling out extrinsic experimental reasons for these findings.
Evolutionary conservation analysis between the essential and nonessential genes in bacterial genomes
Authors: Luo Hao , Gao Feng , Lin Yan
Published: August 2015

Essential genes are thought to be critical for the survival of the organisms under certain circumstances and the natural selection acting on essential genes is expected to be stricter than on nonessential ones. Up to now, essential genes have been identified in approximately thirty bacterial organisms by experimental methods. In this paper, we performed a comprehensive comparison between the essential and nonessential genes in the genomes of 23 bacterial species based on the Ka/Ks ratio and found that essential genes are more evolutionarily conserved than nonessential genes in most of the bacteria examined. Furthermore, we also analyzed the conservation by functional clusters with the clusters of orthologous groups (COGs) and found that the essential genes in the functional categories of G (Carbohydrate transport and metabolism), H (Coenzyme transport and metabolism), I (Transcription), J (Translation, ribosomal structure and biogenesis), K (Lipid transport and metabolism) and L (Replication, recombination and repair) tend to be more evolutionarily conserved than the corresponding nonessential genes in bacteria. The results suggest that the essential genes in these subcategories are subject to stronger selective pressure than the nonessential genes and therefore, provide more insights of the evolutionary conservation for the essential and nonessential genes in complex biological processes.
A novel reflectance-based aptasensor using gold nanoparticles for the detection of oxytetracycline
Authors: Seo Ho Bin , Kwon Young Seop , Lee Ji-eun , Cullen David , Noh Hongseok (Moses) , Gu Man Bock
Published: August 2015

We present a novel reflectance-based colorimetric aptasensor using gold nanoparticles for the detection of oxytetracycline for the first time.
A peptide array-based serological protein kinase A activity assay and its application in cancer diagnosis
Authors: Kong Deok-Hoon , Jung Se-Hui , Jeon Hye-Yoon , Kim Woo-Jin , Kim Young-Myeong , Ha Kwon-Soo
Published: August 2015

Protein kinase A (PKA) plays a crucial role in several biological processes; however, there is no assay with sufficient sensitivity and specificity to determine serological PKA (sPKA) activity.
Halogen bonding assisted selective removal of bromide
Authors: Chakraborty Sourav , Dutta Ranjan , Ghosh Pradyut
Published: August 2015

The selective removal of bromide from a mixture of competing anions through an XB donor receptorviahalogen bonding interactions.
Differentially functionalized acyclic cucurbiturils: synthesis, self-assembly and CB[6]-induced allosteric guest binding
Authors: Zhang Mingming , Sigwalt David , Isaacs Lyle
Published: August 2015

CB[6] functions as an allosteric activator that triggers host·guest recognition processes inside the cavity of self-folded 2HDA.
A highly enantioselective, organocatalytic [3+2]-cycloannulation reaction towards the de novo-synthesis of 1-cyclopentenyl-α-keto esters
Authors: Nareddy Pradeep R. , Schneider Christoph
Published: August 2015

A novel [3+2]-cycloannulation process produces cyclopentenes with good yields and excellent enantioselectivityviaa domino-vinylogous Michael–Knoevenagel reaction.
Structural diversities in Cu(i) and Ag(i) sulfonate coordination polymers and their anion exchange properties
Authors: Singh Suryabhan , Karthik Rajendran
Published: August 2015

Cu(i)/Ag(i) sulfonate CPs have been synthesized and characterized. One of the CPs exhibits a reversible anion exchange for perchlorate and permanganate.
The time scale of the quaternary structural changes in hemoglobin revealed using the transient grating technique
Authors: Yang Cheolhee , Choi Jungkweon , Ihee Hyotcherl
Published: August 2015

The quaternary structural transition between the R and T states of human hemoglobin was investigated using the transient grating technique.
Chemical interaction of water molecules with framework Al in acid zeolites: a periodic ab initio study on H-clinoptilolite
Authors: Valdiviés-Cruz Karell , Lam Anabel , Zicovich-Wilson Claudio M.
Published: August 2015

The hydrated acid clinoptilolite.
An efficient top-down approach for the fabrication of large-aspect-ratio g-C3N4 nanosheets with enhanced photocatalytic activities
Authors: Tong Jincheng , Zhang Li , Li Fei , Li Mingming , Cao Shaokui
Published: August 2015

Rapid and high-yield production of g-C3N4 nanosheets with large aspect ratios by a moderate disintegration–exfoliation approach.
Enhanced activity of H2O2-treated copper(ii) oxide nanostructures for the electrochemical evolution of oxygen
Authors: Handoko Albertus D. , Deng Suzi , Deng Yilin , Cheng Andy Wing Fai , Chan Kuang Wen , Tan Hui Ru , Pan Yanlin , Tok Eng Soon , Sow Chorng Haur , Yeo Boon Siang
Published: August 2015

H2O2-treated CuO nanostructures show 40–68× higher OER activity than Cu nanoparticles.
Accumulation and transformation of nanomaterials in ecological model organisms investigated by using synchrotron radiation techniques
Authors: Li Yunyun , Li Yu-Feng , Zhao Jiating , Gao Yuxi , Chen Chunying
Published: August 2015

Application of SR techniques to study the accumulation and transformation of engineered nanomaterials in different model organisms of terrestrial, aquatic and atmospheric systems.
Glow discharge optical emission spectrometry elemental mapping with restrictive anode array masks
Authors: Kroschk Marcel , Usala John , Addesso Trevor , Gamez Gerardo
Published: August 2015

Restrictive anode array masks are shown to allow large-diameter surface GDOES elemental mapping with improved homogeneity compared to typical approach.
Buckled diamond-like carbon nanomechanical resonators
Authors: Tomi Matti , Isacsson Andreas , Oksanen Mika , Lyashenko Dmitry , Kaikkonen Jukka-Pekka , Tervakangas Sanna , Kolehmainen Jukka , Hakonen Pertti J.
Published: August 2015

Conducting diamond-like carbon is a promising material for high-frequency nanoelectromechanical resonators. Using buckled films increases the frequency tuning of the resonator, which can be of advantage in rf applications.
Synthesis of bicyclic tetrahydrofurans from linear precursors using manganese(iii) acetate
Authors: Chany Anne-Caroline , Marx Léo B. , Burton Jonathan W.
Published: August 2015

Cyclisation of a range of alkoxy-malonates in the presence of manganese(iii) acetate gives rise to bicyclic lactone/THFs and lactone/lactones in synthetically useful yields and diastereoselectivities.
Design of CID-cleavable protein cross-linkers: identical mass modifications for simpler sequence analysis
Authors: Kandur Wynne V. , Kao Athit , Vellucci Danielle , Huang Lan , Rychnovsky Scott D.
Published: August 2015

Cross-linking Mass Spectrometry (XL-MS) is a powerful tool for studying protein-protein interactions. New developments in MS-cleavable linkers further facilitate unambiguous identification of low abundance cross-linked peptides.
Porcine circovirus type 2 affects the serum profile of amino acids and intestinal expression of amino acid transporters in mice
Authors: Xiao Dingfu , Yin Jie , Ren Wenkai , He Jianhua , Hu Xionggui , Yin Yulong , Luo Wei , Yu Xinglong
Published: August 2015

PCV2 is highly pathogenic, however, its effect on the serum amino acids profile is unknown.
9,10-Bis(N-alkylindole-3-yl-vinyl-2)anthracenes as a new series of alkyl length-dependent piezofluorochromic aggregation-induced emission homologues
Authors: Sun Q. K. , Liu W. , Ying S. A. , Wang L. L. , Xue S. F. , Yang W. J.
Published: August 2015

AIE active 9,10-bis(N-alkylindole-3-yl-vinyl-2)anthracene homologues (IACn) could be facilely prepared and exhibit alkyl length-dependent piezofluorochromic properties whose spectral shifts increase with the decrease of N-alkyl chain lengths.
Rational design of nanoparticle/monomer interfaces: a combined computational and experimental study of in situ polymerization of silica based nanocomposites
Authors: De Nicola Antonio , Avolio Roberto , Della Monica Francesco , Gentile Gennaro , Cocca Mariacristina , Capacchione Carmine , Errico Maria Emanuela , Milano Giuseppe
Published: August 2015

Methylmethacrylate monomers/silica nanoparticles interfaces are investigated using simulations and experiments. This allowed to understand and to control interfaces structures. On this basis, an improved in situ polymerization process is proposed.
Quick and simple integration of optical oxygen sensors into glass-based microfluidic devices
Authors: Lasave Liliana C. , Borisov Sergey M. , Ehgartner Josef , Mayr Torsten
Published: August 2015

A novel simple and inexpensive technique for integration of optical oxygen sensors into microfluidic channels made of glass. The channels are coated with conjugated polymeric nanoparticles containing a covalently grafted oxygen indicator.
Space-confined growth of Ag3PO4nanoparticles within WS2sheets: Ag3PO4/WS2composites as visible-light-driven photocatalysts for decomposing dyes
Authors: Hongjian Yu , Yong Yu , Jianghao Liu , Peiyan Ma , Yucheng Wang , Fan Zhang , Zhengyi Fu
Published: August 2015

A highly efficient photocatalyst was synthesized by controlling the growth of Ag3PO4nanoparticles within WS2sheets. This work could provide new insights into fabricating stable Ag3PO4-transition-metal dichalcogenide composite photocatalysts for dye degradation.
Correction: A facile method for preparation of self-healing epoxy composites: using electrospun nanofibers as microchannels
Authors: Vahedi Vahdat , Pasbakhsh Pooria , Chai Siang-Piao , Chan Eng-Seng
Published: August 2015

Correction for ‘A facile method for preparation of self-healing epoxy composites: using electrospun nanofibers as microchannels’ by Vahdat Vahedi et al., J. Mater. Chem. A, 2015, 3, 16005–16012.
Computational and experimental investigation of TmAgTe2and XYZ2compounds, a new group of thermoelectric materials identified by first-principles high-throughput screening
Authors: Zhu Hong , Hautier Geoffroy , Aydemir Umut , Gibbs Zachary M. , Li Guodong , Bajaj Saurabh , Pöhls Jan-Hendrik , Broberg Danny , Chen Wei , Jain Anubhav , White Mary Anne , Asta Mark , Snyder G. Jeffrey , Persson Kristin , Ceder Gerbrand
Published: August 2015

Promising thermoelectric materials (XYZ2) with high band degeneracy and low thermal conductivity.
Bright and efficient blue polymer light emitting diodes with reduced operating voltages processed entirely at low-temperature
Authors: Hoye R. L. Z. , Musselman K. P. , Chua M. R. , Sadhanala A. , Raninga R. D. , MacManus-Driscoll J. L. , Friend R. H. , Credgington D.
Published: August 2015

Efficient and bright blue polyfluorene LEDs, processed entirely below 150 °C, are obtained using an atmospherically synthesized, tunable oxide electron-injector.
Synergistic interaction between lipid-loading and doxorubicin exposure in Huh7 hepatoma cells results in enhanced cytotoxicity and cellular oxidative stress: implications for acute and chronic care of obese cancer patients
Authors: AlGhamdi S. , Leoncikas V. , Plant K. E. , Plant N. J.
Published: August 2015

Doxorubicin and lipid-loading (steatosis) interact synergistically in Huh7 hepatoma cells. This results in enhanced cytotoxicity and pro-inflammatory ROS accumulation.
The metabolism of cholesterol in the presence of liver mitochondria from normal and thyroxine-treated rats
Authors: Mitropoulos KA , Myant NB
Published: August 2015

1. [26-(14)C]- and [4-(14)C]-Cholesterol were incubated with liver mitochondria from normal and thyroxine-treated rats, and the radioactivity was measured in the carbon dioxide evolved during the incubation, in a butanol extract of the incubation mixture and in a volatile fraction containing substances of low molecular weight derived from the side chain of cholesterol. The butanol extract was separated by paper chromatography into three radioactive fractions, one of which contained the steroids more polar than cholesterol. 2. The butanol extract from incubations with [4-(14)C]cholesterol contained a radioactive substance moving with the same R(F) as cholic acid on thin-layer chromatography. 3. After incubation with [26-(14)C]-cholesterol, 60-80% of the radioactivity extracted by steam-distillation of the incubation mixture at acid pH was recovered as [(14)C]propionic acid. 4. In the presence of [26-(14)C]cholesterol, mitochondria from thyroxine-treated rats produced more radioactivity in carbon dioxide and in the volatile fraction, and less radioactivity in the fraction containing the polar steroids, than did mitochondria from normal rats. In the presence of [4-(14)C]cholesterol, mitochondria from thyroxine-treated rats produced the same amount of radioactivity in the polar steroids as did normal mitochondria. 5. Thyroxine treatment had no effect on the capacity of the mitochondria to oxidize propionate to carbon dioxide. 6. These results are best explained by supposing that thyroxine stimulates a rate-limiting reaction leading to the cleavage of the side chain of cholesterol, but has little or no influence on the hydroxylations of the ring system or on the oxidation of the C(3) fragment removed from the side chain.
Studies on the formation of the prothrombin-converting complex
Authors: Jobin F. , Esnouf M. P.
Published: August 2015

1. It has been shown that factor V accelerates the rate of conversion of prothrombin into thrombin by activated factor X, and that this activity does not depend on the presence of phospholipid. 2. Although the mechanism by which factor V increases the rate of reaction is not clear, it seems unlikely that it is converted into an enzyme. 3. The rate of conversion of prothrombin by purified activated factor X and factor V was increased threefold in the presence of phospholipid, and it is suggested that the lipid acts by adsorbing the proteins on its surface and hence increasing the local concentration of the reactants.
Interactions between glycosaminoglycans and proteins, with particular reference to a new technique for isolating serum glycoproteins
Authors: Anderson A. J.
Published: August 2015

1. Chondroitin sulphate-serum protein complexes (A, B and C), successively precipitated by adding chondroitin sulphate to serum at three arbitrary descending pH values (5.2, 4.3 and 3.1), were dissociated at pH 6.7 and chromatographed on DEAE-Sephadex, when the liberated serum proteins were simultaneously freed of chondroitin sulphate and separated into five fractions. Evidence that serum proteins were precipitated as a result of electrostatic interactions with dissociated carboxylate groups on the glycosaminoglycan is presented. 2. Serum proteins (fraction G), unable to form complexes with chondroitin sulphate, contained 4.4% of sialic acid and accounted for 4 and 26% of the total protein and protein-bound sialic acid in serum respectively. This fraction interacted electrostatically with chondroitin sulphate only when rendered more basic by removal of sialic acid residues with neuraminidase. The heat stability, solubility properties and high carbohydrate content of fraction G classified it as a seromucoid fraction. 3. Fraction G contained several glycoprotein and hexuronic acid-containing fractions, including a hitherto undetected brown-pigmented high-molecular-weight serum component, which migrated in starch gel between the origin and Salpha(2)-globulin and contained 3.1 and 4.1% of sialic acid and hexuronic acid respectively. 4. Glycosaminoglycan-protein interactions are discussed in relation to protein fractionation. By prior removal of less acidic proteins by these interactions, a new technique is available for isolating serum seromucoids in higher yields and under milder conditions than existing methods.
Properties of ribosomal proteins from two mammalian sources
Authors: Cohn P.
Published: August 2015

1. Ribosomal protein fractions from rabbit reticulocytes and rat liver were prepared by extracting ribosomes with 0.2n-hydrochloric acid or guanidinium chloride and subsequent dialysis. 2. Treatment for 2.5hr. or less with 0.2n-hydrochloric acid dissolved 46-54% of the proteins, which were richer in arginine and lysine and in N-terminal alanine groups and poorer in aspartic acid and glutamic acid and in N-terminal glycine groups than the acid-insoluble proteins. 3. Protein fractions prepared from the guanidinium chloride extract of ribosomes from rat liver were usually more basic than those from rabbit reticulocytes. 4. The ratios lysine: arginine of fractions in the guanidinium chloride extracts were appreciably higher for proteins from rabbit reticulocytes than from rat liver. 5. The concentration of urea and the pH of the gel affected the rate of migration and number of bands in starch-gel electrophoresis.
Inhibition of glucose phosphate isomerase by metabolic intermediates of fructose
Authors: Zalitis J. , Oliver I. T.
Published: August 2015

1. Purified rabbit-muscle and -liver glucose phosphate isomerase, free of contaminating enzyme activities that could interfere with the assay procedures, were tested for inhibition by fructose, fructose 1-phosphate and fructose 1,6-diphosphate. 2. Fructose 1-phosphate and fructose 1,6-diphosphate are both competitive with fructose 6-phosphate in the enzymic reaction, the apparent K(i) values being 1.37x10(-3)-1.67x10(-3)m for fructose 1-phosphate and 7.2x10(-3)-7.9x10(-3)m for fructose 1,6-diphosphate; fructose and inorganic phosphate were without effect. 3. The apparent K(m) values for both liver and muscle enzymes at pH7.4 and 30 degrees were 1.11x10(-4)-1.29x10(-4)m for fructose 6-phosphate, determined under the conditions in this paper. 4. In the reverse reaction, fructose, fructose 1-phosphate and fructose 1,6-diphosphate did not significantly inhibit the conversion of glucose 6-phosphate into fructose 6-phosphate. 5. The apparent K(m) values for glucose 6-phosphate were in the range 5.6x10(-4)-8.5x10(-4)m. 6. The competitive inhibition of hepatic glucose phosphate isomerase by fructose 1-phosphate is discussed in relation to the mechanism of fructose-induced hypoglycaemia in hereditary fructose intolerance.
Studies of the chemical composition of a healing skin wound in rats, and of the concentrations of some constituents of tissues distant from the healing wound
Authors: Candlish J , Chandra N.
Published: August 2015

1. A skin lesion was made in rats by dorsal incision and the insertion of a polythene tube. 2. Over a period of 25 days after wounding, assays were performed for ascorbic acid, DNA, hydroxyproline, methionine, tryptophan, tyrosine and free amino acids in the lesion tissue. 3. The neutral-salt-soluble proteins of the lesion tissue were fractionated on DEAE-Sephadex, with the separation of fibrinogen and gamma-globulin from a serum protein fraction. 4. Over a period of 20 days after wounding, in wounded rats and in controls, assays were conducted for: ascorbic acid in lens and liver, hydroxyproline, soluble protein, methionine and water in muscle and tendon, and free amino acids in muscle. 5. Relative to controls there was a decrease in lens and liver ascorbic acid, a rise in tendon hydroxyproline, a rise in muscle free amino acids, a fall in muscle protein and a rise in tendon and muscle water.
Vitamin B12 in photosynthetic bacteria and methionine synthesis by Rhodopseudomonas spheroides
Authors: Cauthen S. E. , Pattison J. R. , Lascelles J
Published: August 2015

1. Assay of some photosynthetic bacteria for vitamin B(12) showed them to be relatively rich in this factor. Rhodopseudomonas spheroides, grown photosynthetically in Co(2+)-supplemented medium, contained about 100mug./g. dry wt. 2. Extracts of wild-type Rps. spheroides methylated homocysteine by a mechanism similar to the cobalamin-dependent pathway present in Escherichia coli. However, no mechanism similar to the cobalamin-independent N(5)-methyltetrahydrofolate-homocysteine transmethylase of E. coli could be detected in Rps. spheroides. 3. N(5)N(10)-Methylenetetrahydrofolate-reductase activity was found in Rps. spheroides. 4. A methionine-requiring mutant strain of Rps. spheroides (strain 2/33), which does not respond to homocysteine, made the same amount of vitamin B(12) as the parent organism. Extracts did not form methionine from N(5)-methyltetrahydrofolate and homocysteine even in the presence of cofactors shown to be necessary with the parent strain, and it is concluded that the mutant is blocked in the formation of the apoenzyme of a homocysteine-methylating system similar to the vitamin B(12)-dependent one in E. coli.
Changes in lipid synthesis in rat liver during development
Authors: Ballard F. J. , Hanson R. W.
Published: August 2015

1. Lipogenesis, as measured by the incorporation of (14)C-labelled glucose or acetate into fatty acids in liver slices, is high in foetal and adult rat liver but is low in the liver of the suckling rat, especially with glucose as substrate. 2. The rate of synthesis of non-saponifiable lipids from glucose is about 15 times as great in the liver of the 18-day foetus as in adult liver. Activity in the newborn is negligible. 3. Glucose incorporation into fat is strongly concentration-dependent in liver slices from the adult and 2-week-old rat, but less markedly so in liver slices from the foetus. 4. Changes in the activity of hepatic citrate-cleavage enzyme (ATP-citrate lyase) occur in parallel with the changes in the extent of fatty acid formation, supporting the participation of this enzyme in lipogenesis. However, NADP-malate dehydrogenase, a potential source of reduced nucleotide coenzyme for lipogenesis in the adult, could not be detected in foetal rat liver.
A procedure for the quantitative analysis of the sulphur amino acids of rat tissues
Authors: Gaitonde M. K. , Gaull G. E.
Published: August 2015

1. A method is described for the quantitative separation of the sulphur compounds in a single sample of tissue by passing an extract through a serial assembly of ion-exchange resins in the order: Dowex 2 (Cl(-) form), Dowex 1 (CO(3) (2-) form), Amberlite CG-50 (H(+) form) and Zeo-Karb 225 (H(+) form). 2. Groups of sulphur amino acids were eluted separately from each column; the recovery of sulphur compounds after their labelling with (35)S in vivo by injection of l-[(35)S]-methionine was 91-106%. Individual sulphur compounds were further resolved by one-dimensional or two-dimensional paper chromatography. 3. Evidence is presented on the occurrence of S-adenosylmethionine and S-adenosylhomocysteine in rat liver and brain. Rat liver and brain contained 83.6 and 31.4mmu-moles/g. respectively of S-adenosylmethionine.
Esterification of glycerol 3-phosphate in lactating guinea-pig mammary gland
Authors: Kuhn N. J.
Published: August 2015

1. The presence of palmitoyl-CoA–l-glycerol 3-phosphate palmitoyltransferase (EC 2.3.1.15) has been demonstrated in a particulate fraction of mammary tissue from lactating guinea pigs. 2. Cell-free preparations also catalysed the activation of palmitate and oleate, and the conversion of enzymically formed phosphatidic acid into glycerides, in accord with the Kennedy pathway of glyceride formation. 3. The properties of the system that esterifies l-glycerol 3-phosphate were studied with respect to substrates and cofactors, and the reaction product was shown to be phosphatidic acid (1,2-diacyl glycerol 3-phosphate). 4. The extent to which newly formed phosphatidic acid was converted into glyceride in a cell-free system was dependent on the nature of the acyl donor, the concentration of subcellular particles, the time of incubation and the concentration of Mg2+.
Regulation of triglyceride synthesis in the parturient guinea-pig mammary gland
Authors: Kuhn N. J.
Published: August 2015

1. The specific activity of the enzyme palmitoyl-CoA–l-glycerol 3-phosphate palmitoyltransferase (EC 2.3.1.15) in the mammary tissue of guinea pigs has been shown to increase 37-fold at parturition. 2. Increases also occur in tissue concentrations of glycerol 3-phosphate, CoA and free fatty acid, but not in that of acid-insoluble CoA. 3. The isolation and fatty acid composition of plasma triglyceride and of mammary-tissue free fatty acid, diglyceride and triglyceride are described. 4. The findings are discussed in relation to the regulation of milk fat synthesis.
Resistance of Escherichia coli to tetracyclines. Changes in permeability to tetracyclines in Escherichia coli bearing transferable resistance factors
Authors: Franklin T J
Published: August 2015

1. When strains of Escherichia coli, bearing transferable factors for resistance to the tetracyclines (R-factors), and previously cultured in the absence of the tetracyclines, are grown for 15–30min. in a low, subinhibitory, concentration (10μg./ml.) of oxytetracycline or tetracycline, there is a rapid and striking increase in resistance to oxytetracycline or tetracycline, this being associated with a marked fall in the absorption of the drug by the cells. 2. Very short preincubation (1min.) with oxytetracycline, followed by growth for 15–30min. in drug-free medium, produces a marked fall in the absorption of the drug by the resistant cells. Preincubation for 30min. with very low concentrations (0·05μg./ml.) of oxytetracycline produces a similar effect. 3. β-Apo-oxytetracycline, which has very little antibacterial activity, also induces a decreased absorption of oxytetracycline. 4. The ability to exclude oxytetracycline is retained by preincubated resistant cells after growth for 2hr. in drug-free medium. However, after growth for 16hr. in drug-free medium, the cells absorb oxytetracycline freely. 5. Chloramphenicol and proflavine inhibit the adaptive decrease in tetracycline absorption. 5-Fluorouracil has only a slight effect. 6. Spheroplasts prepared from resistant cells show an impaired response to preincubation with tetracycline, compared with intact cells. 7. The relevance of these results to the probable mechanism of tetracycline resistance in R-factor-bearing E. coli is discussed.
Amino acid composition of human fibrinogen and anticoagulant derivatives
Authors: Triantaphyllopoulos E. , Triantaphyllopoulos D. C.
Published: August 2015

1. The amino acid compositions of human fibrinogen and three intermediate anticoagulant derivatives were determined by column chromatography. The derivatives were isolated by ammonium sulphate fractionation and column electrophoresis from solutions of fibrinogen undergoing spontaneous breakdown. One derivative, isolated as the large electrophoretic peak at the end of the clottable period (100% CP) of the parent fibrinogen solution, was labelled LP100 and others obtained at twice this period (200% CP) were designated as LP200 and SP200 (LP, large peak; SP, small peak). 2. Maximal ‘molecular’ weights of approx. 294000 for LP100, 137000 for LP200 and 37000 for SP200 were calculated for the protein moieties. At least 265 amino acid residues must have been lost from each fibrinogen molecule during the formation of LP100, and 1362 during the formation of the other two derivatives. 3. Only one derivative (LP200) had a partial specific volume ([unk] 0·725ml./g.) different from that of fibrinogen ([unk] 0·721ml./g.). 4. No significant differences in refractive index at 589mμ were detected. 5. Calculation of the total number of ionizable groups/105g. of each protein moiety showed a preponderance of the following numbers of negative charges: 22 in fibrinogen; 24 in LP100; 26 in LP200; 49 in SP200. The isoionic points were estimated to be approx.+0·03pH unit (for fibrinogen), −0·06pH unit for (LP100) and +0·28pH unit (for LP200) from the pK of imidazole, and 0·78pH unit above the average pK of aspartyl and glutamyl ions (for SP200). These figures agree closely with experimentally determined values of the isoelectric point of fibrinogen and its derivatives.
Studies on glycogen synthesis in pigeon liver homogenates. Glycogen synthesis from glucose monophosphates and uridine diphosphate glucose
Authors: Nigam V. N.
Published: August 2015

Comparative time-course studies of glycogen synthesis from glucose 6-phosphate, glucose 1-phosphate and UDP-glucose show that glucose 1-phosphate forms glycogen at an initial rate faster than that obtained with glucose 6-phosphate and UDP-glucose. After 5min. the rates from glucose monophosphates are considerably slower. 2,4-Dinitrophenol decreases glycogen synthesis from both glucose monophosphates, whereas arsenate and EDTA increase glycogen synthesis from glucose 1-phosphate and inhibit the reaction from glucose 6-phosphate, galactose and galactose 1-phosphate. Mitochondria-free pigeon liver cytoplasmic fraction forms less glycogen from glucose monophosphates than does the whole homogenate. 2-Deoxyglucose 6-phosphate inhibits glycogen synthesis from glucose monophosphates. Glycogen formation from UDP-glucose is relatively unaffected by dinitrophenol, by arsenate, by EDTA, by 2-deoxyglucose 6-phosphate and by the removal of mitochondria from the whole homogenate.
The glucoamylase of Coniophora cerebella
Authors: King N. J.
Published: August 2015

1. The major amylolytic enzyme in culture filtrates of Coniophora cerebella grown in starch-containing media has been purified and characterized as a glucoamylase (EC 3.2.1.3). 2. The activity/unit wt. of protein was increased 11-fold and the enzyme showed one major component on polyacrylamide-gel electrophoresis. 3. The glucoamylase had optimum pH4·0–4·5. 4. Hg2+ completely inhibited the enzyme, but other ions tested had little effect on the activity at the concentration of ions used (5mm). 5. The action of the enzyme on amylopectin, amylose and maltose was studied. Hydrolysis proceeded by the stepwise removal of glucose units from the non-reducing ends of the polymer chains, and the enzyme was able to bypass or to hydrolyse the α-(1→6)-glucosidic linkages at branch points in the amylopectin molecule. Glucose was the only product found in digests of these substrates. 6. At the same substrate concentration (0·1%, w/v) and enzyme concentration, the initial rates of glucose production from amylopectin, amylose and maltose were in the proportions 40:10:1. 7. Km values at 40° and pH4·0 were calculated for the enzyme acting on amylopectin, amylose and maltose.
Studies on ox brain aminopeptides
Authors: Brecher A. S. , Sobel R. E.
Published: August 2015

1. Mn2+-inhibited and Mn2+-activated aminopeptidases have been observed in ox brain and separated from one another by DEAE-cellulose column chromatography. 2. The Mn2+-inhibited enzyme has been purified 36-fold; it exhibits a specificity for tripeptide substrates, whereas the Mn2+-activated aminopeptidase cleaves dipeptides as well as tripeptides. 3. Ammonium sulphate treatment generates a Mn2+-stimulated aminopeptidase that is stable to dialysis against EDTA and water, in contrast with an endogenous Mn2+-activated preparation that is irreversibly denatured by such dialysis against EDTA and water.
Enzymic glucosylation of phenols
Authors: Hopkinson Shirley M. , Pridham J. B.
Published: August 2015

1. A transglucosylase fraction has been obtained from the mycelium of Aspergillus niger. 2. The preparation will transfer α-d-glucopyranosyl residues from maltose and other α-d-glucopyranosides to phenolic and alcoholic hydroxyl groups and to carboxylic acid groups. 3. α-Isomaltosides and α-maltosides are formed when resorcinol and catechol are used as acceptors. 4. pH precipitation and DEAE-cellulose chromatography were used to resolve the activity into two fractions. The properties, in particular polyol inhibition, of one of these fractions have been examined in detail.
The equilibrium constants of the glutamate dehydrogenase systems
Authors: Engel P. C. , Dalziel K.
Published: August 2015

1. Equilibrium constants for the oxidation of glutamate by NAD+ and NADP+, catalysed by glutamate dehydrogenase, have been measured in phosphate buffers of different ionic strengths and at several temperatures. 2. The equilibrium constants for both systems vary markedly with ionic strength. Thermodynamic values for the two systems obtained by extrapolation to zero ionic strength differ significantly from one another. The standard free-energy change for NADP+ reduction has been calculated from that for NAD+ reduction. 3. The heat of reaction has been estimated and is the same with both coenzymes. 4. The thermodynamic data are discussed in relation to earlier data.
Intracellular concentration of cysteine in Escherichia coli and its relation to repression of the sulphate-activating enzymes
Authors: Wheldrake J. F.
Published: August 2015

1. The intracellular cysteine and glutathione concentrations were measured in Escherichia coli under a variety of growth conditions. 2. An inverse relation between intracellular cysteine concentration and the specific activity of the sulphate-activating enzymes was found. 3. This is compatible with the view that the intracellular cysteine concentration controls the rate of synthesis of these enzymes.
Identification of guanosine diphosphate derivatives of d-xylose, d-glucose and d-galactose in mature strawberry leaves
Authors: Selvendran R. R. , Isherwood F. A.
Published: August 2015

The nucleotides from a trichloroacetic acid extract of mature strawberry leaves were separated into ten main fractions by chromatography on a Dowex 1 (formate form) column with ammonium formate as the eluting agent. One of these fractions, which was suspected to contain not only ADP but also GDP-sugars, was separated into a number of subfractions by further chromatography on a Dowex 1 (formate form) column with the formic acid system as the eluting agent. One of these subfractions was identified from its ultraviolet spectra, from its position on the two ion-exchange columns and by thin-layer chromatography as a GDP-sugar. Mild acid hydrolysis gave GDP and a mixture of sugars. The sugars, after a preliminary separation on a paper chromatogram, were identified by an isotope-dilution method. The sugars were condensed with sodium [14C]cyanide, the [14C]nitriles were hydrolysed and one of the epimeric acids was isolated, either as lactone or amide, by co-crystallization with a non-radioactive carrier. This method distinguishes between enantiomorphic sugars. d-Mannose, d-xylose, d-glucose and d-galactose were present in the proportions 40:10:1:1 respectively. The total amount of the GDP-sugars was approx. 0·1μmole/100g. of fresh leaves.
The cell walls of Pseudomonas aeruginosa. General composition
Authors: Clarke K. , Gray G. W. , Reaveley D. A.
Published: August 2015

1. Cell walls of Pseudomonas aeruginosa were prepared and analysed. 2. Separate preparations were found to be reproducible, e.g. the phosphorus contents of all batches lay in the range 2·0–2·1%. 3. Ninhydrin-positive compounds in hydrolysates accounted for 43–46% of the cell wall and 79–87% of the nitrogen of the cell wall. Examination of the results for individual ninhydrin-positive compounds showed that 5–15% of the cell wall was murein and about 30% protein. 4. Trypsin treatment of crude cell-wall preparations preferentially liberated arginine, lysine and leucine, but it was not clear whether these arose from cell-wall or cytoplasmic proteins.
Metabolic changes during phosphate deprivation in Englena in air and in oxygen
Authors: Blum J. J. , Bégin-Heick Nicole
Published: August 2015

1. Euglena cells were grown in culture media containing either 20mm-phosphate or 20μm-phosphate, with ethanol or glucose as the sole source of carbon, and gassed with either air+carbon dioxide (95:5) or oxygen+carbon dioxide (95:5) at atmospheric pressure. 2. After growth in low-phosphate medium with ethanol as substrate, the cells developed signs of oxygen toxicity, as indicated by a decreased rate of respiration, a decreased net synthesis of paramylum and a failure to resume growth on replenishment of phosphate. 3. After growth in low-phosphate medium with glucose as substrate, the signs of oxygen toxicity were less apparent. 4. During phosphate deprivation the carotenoid content of Euglena increased more than threefold. This increase was largely prevented by exposure of the cells to oxygen+carbon dioxide (95:5) during growth. Oxygenation appears to interfere with ring closure of the common carotenoid precursor. 5. Mitochondria obtained from Euglena exposed to oxygen during phosphate deprivation, i.e. when signs of oxygen toxicity were evident, had greatly decreased activities of succinate dehydrogenase, succinate–cytochrome c oxidoreductase and NADH–cytochrome c oxidoreductase, compared with mitochondria obtained from Euglena exposed to oxygen in medium containing 20mm-phosphate.
14α-Hydroxyoestrone, a new oestrogen metabolite
Authors: Knuppen R. , Haupt O. , Breuer H.
Published: August 2015

1. Incubation of oestrone with ox adrenal glands leads to the formation of two main metabolites, one of which has recently been identified as 15α-hydroxyoestrone; the second metabolite (Oe-5) has now been obtained in crystalline form and identified as the hitherto unknown 14α-hydroxyoestrone. 2. The identity of compound Oe-5 with 14α-hydroxyoestrone was confirmed conclusively by comparison with 14α-hydroxyoestrone that was synthesized by pyrolytic aromatization of 14α-hydroxyandrosta-1,4-diene-3,17-dione. 3. The physical and chemical properties as well as the oestrogenic activity of 14α-hydroxyoestrone are described. 4. The biogenesis and metabolism of 14α-hydroxyoestrone were studied in various tissue preparations.
Separation of urinary oestrogen sulphates from oestrogen glucosiduronates on diethylaminoethyl-Sephadex columns
Authors: Hähnel Roland , Rahman M. Ghazali Bin Abdul
Published: August 2015

1. Gradient elution (sodium chloride concentration gradient) on DEAE-Sephadex columns is used to separate urinary oestrogen conjugates of pregnancy urine. Changes in the shape of the gradient alter the chromatograms in a predictable manner so that the dispersion of peaks can be modified at will. 2. Suitable choice of the gradient results in the separation from each other of oestrogen sulphates, oestrogen 16(or 17)-glucosiduronates, oestrogen 3-glucosiduronates and free oestrogens. 3. Evidence for the presence of oestriol 3-sulphate, oestrone 3-sulphate, 17β-oestradiol 3-sulphate, 16-oxo-17β-oestradiol 3-sulphate and oestriol 16(or 17)-sulphate in the sulphate fraction of DEAE-Sephadex chromatograms of pregnancy urine is provided.
The kinetics and reaction mechanism of the nicotinamide–adenine dinucleotide phosphate-specific glycerol dehydrogenase of rat skeletal muscle
Authors: Toews C. J.
Published: August 2015

The NADP-specific glycerol dehydrogenase of rat skeletal muscle has been partially purified by ammonium sulphate fractionation. The enzyme has been studied kinetically by initial-velocity analysis, product inhibition and inhibition by fluoride. The experimental results indicate that the reaction mechanism for the enzyme is ordered such that the first product leaves the enzyme before the addition of the second substrate.
Partition of porphyrins between cyclohexanone and aqueous sodium acetate as a function of pH. Determination of uroporphyrin and of hydrophilic porphyrin conjugates
Authors: Rimington C. , Benson A.
Published: August 2015

1. The partition of uroporphyrins I and III, coproporphyrins I and III, haematoporphyrin IX, porphyrin c and a hydrophilic porphyrin–peptide fraction from variegate-porphyria faeces has been studied in systems of equal volumes of cyclohexanone and sodium acetate buffers of varying pH and concentration. 2. The concentration of acetate in the aqueous phase has little effect on the partition of porphyrin c, but markedly influences that of uroporphyrin. At 50% acetate saturation and pH4·5, only 5% enters the cyclohexanone phase whereas 60% of porphyrin c is extracted under similar conditions. 3. This circumstance forms the basis of a method for the determination of hydrophilic porphyrin–peptides in variegate-porphyria urine. Its reliability has been checked in model experiments. 4. At pH1·5 and an aqueous phase half-saturated with sodium acetate, an equal volume of cyclohexanone removes 95–97% of uroporphyrin and about 55% of porphyrin c. Uroporphyrin may therefore be determined as a second step in the method. 5. For the routine determination of uroporphyrin in systems free from other hydrophilic porphyrins, cyclohexanone extraction may be performed at any pH in the range 1·0–3·0.
Messenger ribonucleic acid of cerebral nuclei
Authors: Bondy S. C. , Roberts Sidney
Published: August 2015

1. RNA was isolated from crude nuclear preparations and from ribosomes derived from rat brain and liver. Nuclear RNA was obtained by lysis of the nuclei with sodium dodecyl sulphate, followed by denaturation and removal of DNA and protein with hot phenol. 2. Base composition analyses indicated that the cerebral nuclear RNA preparation contained a higher proportion of non-ribosomal RNA than the analogous hepatic preparation. 3. Sucrose-density-gradient analyses revealed a heterogeneous profile for each nuclear RNA preparation, with two major peaks possessing the sedimentation properties of ribosomal RNA (18s and 28s). 4. Template activities of both preparations were widely distributed through the sucrose density gradients. 5. The cerebral nuclear RNA preparation was more active than the hepatic nuclear RNA preparation in promoting amino acid incorporation in cell-free systems from Escherichia coli and rat brain. 6. Cerebral nuclear RNA stimulated amino acid incorporation in a cerebral ribosomal system even in the presence of an excess of purified E. coli transfer RNA. 7. It is concluded that a significant proportion of cerebral nuclear RNA has the characteristics of messenger RNA.
The binding of calcium and yttrium ions to a glycoprotein from bovine cortical bone
Authors: Williams P A , Peacocke A. R.
Published: August 2015

The binding of Ca2+ and Y3+ to an acidic glycoprotein from bovine cortical bone, bone sialoprotein, was determined from the titration curves at I 0·2 in the presence and absence of the cations. The binding of Y3+ was greater than that of Ca2+. The value for the association constant, k, for the interaction with Y3+ increased with pH, from log k 2·93 at pH3·4 to log k 3·50 at pH4·4, and the number of binding sites/mol. increased from 4·6 at pH3·4 to 9·1 at pH4·4. It is proposed that the binding site consists of three carboxyl groups, but it is likely that the binding is a strong electrostatic interaction rather than a co-ordination linkage. A chondroitin sulphate–protein complex also extracted from bovine cortical bone interacted with Y3+ and Ca2+ to a similar extent as did bone sialoprotein. It is suggested that these materials are present in bone at the resting and resorbing surfaces and that they contribute to the deposition of yttrium, americium and plutonium at these sites.