bluuebunny/crossref_metadata_2025_split huggingface dataset:
Acid triacylglycerol lipase from bovine thyroid gland
Authors: De Wolf M. , Lagrou A. , Hilderson H. J. , Dierick W. 
Published: December 2006

AbstractAn acid lipase has been detected in bovine thyroid tissue using triolein as a substrate. The activity, probably associated with the lysosomes, displays a rather broad pH‐optimum in the pH 4 to pH 6.5 range. The lipase activity can be partially purified by cosedimentation with lysosomes followed by solubilization through detergent and chromatography on Sephadex G‐200 and carboxymethyl cellulose. The elution profile on Sephadex G‐200 shows one peak (moleculare weight 67,000±2,000). In the final CM‐cellulose step, two lipase peaks (lipase LA and lipase LB) are found. Sulhydryl reagents (iodoacetate, iodoacetamide, and N‐ethylmaleimide) as well as mercuric ions markedly reduce both enzyme activities. Calcium ions, EDTA, and heparin have no effect. Sodium fluoride and diisopropylfluorophosphate are only slightly inhibitory. Sodium chloride causes a slight increase in both lipase activities. Anionic phospholipids such as cardiolipin and phosphatidylserine are not essential for enzyme activity.
Effects of three dietary fats on plasma lipids and lipoproteins in fasting and post‐prandial humans after a short‐term diet
Authors: Baudet M. F. , Esteva O. , Delplanque B. , Winchenne N. , Jacotot B. 
Published: December 2006

AbstractThe effects of 3 dietary fats (olive oil, canbra oil and butter) on the fatty acids of blood lipids and on serum lipoproteins were compared in 6 healthy adult outpatients, after a 6‐day normocaloric diet including 35% of the studied fat. Important, although incomplete, changes appeared in the fatty acid composition of the various serum lipids and in the composition and distribution of serum lipoproteins. These changes probably result from the degree of saturation of the fat ingested. Moreover, differences were observed among individual subjects. Genetic differences, which are important in clinical practice, are stressed in connection with risks of vascular diseases and hyperlipidemia and affect intestinal fat absorption and lipoprotein metabolism.
Metabolism of erucic acid in adipocytes isolated from rat epididymal fat
Authors: Christophersen Bjorn , Krogstad Torild , Norseth Jon 
Published: December 2006

AbstractThe metabolism of [14‐14C]erucic acid and [U‐14C]palmitic acid has been investigated in adipocytes isolated from rat epididymal fat. The rate of acylation of [14C]erucic acid in cellular lipids and oxidation to CO2 and acid‐soluble activity was ca. 1/3 of the rate with [14C]palmitic acid as substrate. A maximal incorporation of fatty acids in triacylglycerol was found at a fatty acid concentration of 0.8 mM in the medium, both with [14C]erucic acid and [14C]palmitic acid as substrate. Glucose added to the medium increased the esterification and decreased the oxidation of both fatty acids. No significant chain‐shortening of [14C]erucic acid to shorter monoenes was identified in the fat cells. Increasing concentrations of unlabeled palmitic acid in the incubation medium markedly inhibited the esterification of [14C]erucic acid, whereas unlabeled erucic acid had little effect on the rate of esterification of [14C]palmitic acid.
Levels of polyunsaturated fatty acids in tissues from zinc‐deficient rats fed a linseed oil diet
Authors: Eder Klaus , Kirchgessner Manfred 
Published: December 2006

AbstractThe effect of zinc deficiency on the levels of n−6 and n−3 polyunsaturated fatty acids (PUFA) in lipids from tissues of rats fed a diet containing linseed oil was investigated. Rats were fed either a control diet (25 mg Zn/kg) or a zinc‐deficient diet (0.8 mg Zn/kg) for 10 d. To avoid energy and nutrient deficiency, 11.6 g of diet per day was administered by gastric tube. At the end of the experiment, rats fed the zinc‐deficient diet had drastically reduced plasma zinc concentration and alkaline phosphatase activity consistent with severe zinc deficiency in these rats. Zinc‐deficient rats had higher levels of n−3 PUFA, in particular eicosapentaenoic acid (EPA), and lower levels of n−6 PUFA, in particular linoleic acid, in liver and plasma phosphatidylcholine (PC) and in erythrocyte membrane total lipids than did control rats. By contrast, the levels of n−3 PUFA in PC from testes and heart, and in phosphatidylethanolamine (PE) from liver, testes and heart, were only slightly different between zinc‐deficient and control rats. The study suggests that desaturation of α‐linolenic acid is not inhibited by zinc deficiency, and that in zinc‐deficient rats, n−3 PUFA preferentially incorporated into phospholipids at the expense of n−6 PUFA, especially EPA into PC. The study also shows that the effect of zinc deficiency on PUFA levels is different for PC and PE in rat tissues.
Reactions of diazomethane with glycerolipids in the presence of serum or inorganic salts
Authors: Schmid Patricia C. , Schmid Harald H. O. 
Published: December 2006

AbstractDiazomethane is widely used for the selective methylation of nonesterified fatty acids in the presence of other lipids. However, when the reaction is carried out directly with plasma or serum, substantial methanolysis of phospholipid acyl groups occurs. Because of the importance of rigorous selectivity in the assay of unesterified fatty acids which are present only in trace amounts in cells and body fluids, we have investigated the diazomethane procedure in detail and reached the following conclusions: (i) When diazomethane reacts with lipid extracts in organic solvent, no ester hydrolysis occurs. (ii) In the presence of serum or plasma, diazomethane reacts with water and inorganic salts, causing the solution to become basic (CH2N2+NaCl+HOH→CH3Cl+Na++OH−+N2); methoxide ions are formed from methanol (CH3OH+OH−→CH3O−+HOH) causing extensive methanolysis (CH3O−+RO−CO−R′→CH3O−CO−R′+RO−). An analogous reaction takes place with ethanol. All esters of glycerol are transesterified in aqueous salt solution by this mechanism. It is therefore essential to prepare a lipid extract prior to the assay of unesterified fatty acids when using the diazomethane procedure.
The influence of exogenous cholesterol on the fatty acid composition of liver lipids in the rats given linoleate and γ‐linolenate
Authors: Takayasu Ken , Yoshikawa Iwao 
Published: December 2006

AbstractThree groups of rats were given cholesterol and cholic acid for four weeks, and then fed a diet with 20% lard (group 1), a diet with 4% of the lard substituted by methyl linoleate (group 2), and a diet with 2% substituted by methyl linoleate and another 2% by methyl γ‐linolenate (group 3) during the same period. Two control groups (4 and 5) received the same diets as did groups 2 and 3, respectively, but without cholesterol and cholic acid. The hepatic cholesterol accumulation was significantly less in group 3 than in groups 1 and 2, and distinct differences in the degree of plasma cholesterol elevation were found among the cholesterol fed groups (1>2>3). Supplement of γ‐linolenate resulted in a reduction of the ratio of arachidonate to homo‐γ‐linolenate in both the cholesterol‐fed group and the control group, but the ratio was much lower in the former. Incorporation of 1‐14C‐linoleate and 1‐14C‐γ‐linolenate into the liver lipids of groups 2 and 4, and groups 3 and 5 was observed respectively at 1 and 3 hr after the intravenous injection. The specific activity of arachidonate from both of the labeled acids in phospholipid and triglyceride was apparently lower in groups 2 and 3 than in groups 4 and 5, respectively. The distribution rate of radioactivities in tetraenoic acids was also low in groups 2 and 3 among the fatty acids of phospholipid and triglyceride. The results indicated impairment of conversion of homo‐γ‐linolenate into arachidonate in the cholesterol‐fed rats.
Effect of 6‐substituted sterols on sterol‐induced reproduction inPhytophthora cactorum
Authors: Elliott C. G. , Math V. B. 
Published: December 2006

Abstract6‐Methylcholesterol and 6‐ketocholestanol do not promote oospore development inPhytophthora cactorum when added as sole sterol supplement of media, and they inhibit development induced by cholesterol. 6‐Fluorocholesterol promotes oospore formation; 6‐chlorocholesterol does not, and neither inhibits cholesterol‐induced development. A strain ofP. cactorum has been found which is exceptional among Phytophthoras or Pythiums examined hitherto in forming numberous oospores with cholestanol. In this strain, 6‐ketocholestanol inhibits cholestanol‐induced oospore formation. These results indicate the importance of C‐6 as a point of interaction with cellular sites controlling oospore formation.
Iodination of arachidonic acid by the iron/H2O2/iodide system
Authors: Henderson William R. , Hubbard Walter C. , Klebanoff Seymour J. 
Published: December 2006

AbstractThe newly described iron/hydrogen peroxide (H2O2)/iodide antimicrobial system iodinates arachidonic acid to form the same products which are generated by peroxidase/H2O2/iodide systems. Arachidonic acid is multiply iodinated with the formation ofbis‐iodohydrins and monoiodinated products which were identified as iodolactones by their high performance liquid chromatography elution patterns and by gas chromatography‐mass spectrometric analysis. Iodination of arachidonic acid by the iron/H2O2/iodide system appears to proceed via the formation of hydroxyl radicals as an intermediate species. Iodination of unsaturated lipids may contribute to the cytotoxicity of the iron/H2O2/iodide system.
Serum lipoprotein hydrolysis by purified lipases
Authors: Fried Melvin , Chorvath Branko 
Published: December 2006

AbstractPurified lipases from pork pancreas,Rhizopus arrhizus andLeptospira biflexa hydrolyze the triglycerides of pork very low density lipoproteins (VLDL), while higher density lipoproteins are not affected significantly. The velocity versus substrate curves for the VLDL were sigmoid.
Chromatin supraorganization, DNA fragmentation, and cell death in erythrocytes of the rattlesnake, Crotalus durissus terrificus (Serpentes, Viperidae), infected with the protozoan, Hepatozoon spp. (Apicomplexa, Hepatozoidae)
Authors: Miyamoto Maristela , Mello Maria Luiza S. 
Published: December 2006

AbstractForms of the protozoan of the Hepatozoon genus are detected free in the circulation and also within some of the erythrocytes of infected snakes. In healthy snakes, DNA fragmentation and cell death usually affect a few circulating erythrocytes in agreement with the long life span expected for these cells. In the present study we investigated whether infection by Hepatozoon spp. affected the incidence of DNA fragmentation and cell death in erythrocytes from the rattlesnake, Crotalus durissus terrificus. Methods such as the kinetics of Feulgen‐DNA hydrolysis, and the TUNEL and comet assays, previously used for the study of chromatin organization and DNA fragmentation in erythrocytes of healthy snakes, were used. The results indicated that Hepatozoon spp. increased the DNA fragmentation and chromatin condensation typical of cell death in circulating erythrocytes of C. d. terrificus, including cells that do not harbour the parasite. The Hepatozoon infection is thus suggested to accelerate destruction of erythrocytes in the rattlesnake, not only affecting cells harbouring the parasite, but also in those without it.
Inhibition of prolyl 4‐hydroxylase prevents left ventricular remodelling in rats with thoracic aortic banding
Authors: Fielitz Jens , Philipp Sebastian , Herda Lars Roman , Schuch Evelyn , Pilz Bernhard , Schubert Carola , Günzler Volkmar , Willenbrock Roland , Regitz‐Zagrosek Vera 
Published: December 2006

AbstractBackground:Pressure overload leads to myocardial remodelling with collagen accumulation, left ventricular hypertrophy (LVH), neurohormonal activation and myocardial dysfunction. Prolyl 4‐hydroxylases (P4H) are involved in collagen maturation. Inhibition of P4H has been shown to prevent LV remodelling and improve survival post‐myocardial infarction.Aim:To evaluate the role of P4H in pressure overload‐induced myocardial remodelling.Methods:Male Wistar rats underwent thoracic aortic banding (AoB) and were treated with a P4H inhibitor (P4HI) or vehicle (control). Echocardiography and haemodynamic measurements were performed after 4 weeks. Collagens, matrix metalloproteinases (MMP), tissue inhibitors of MMPs (TIMP), growth factors and neurohormonal markers were quantitated in LV samples.Results:AoB led to LVH, increased LV enddiastolic pressure (LVEDP) and decreased contractility compared to sham. P4HI reversed these effects. AoB increased collagen I and III expression, which was normalized by P4HI. AoB led to deregulation of matrix remodelling enzymes, enhanced expression of growth factors and activation of the endothelin system. P4HI partially prevented deregulation of the MMP/TIMP system, inhibited upregulation of growth factors and normalized AoB‐induced ECE‐1 and ETB expression.Conclusions:P4HI leads to an improvement of AoB‐associated LV dysfunction and reduces imbalance of extracellular matrix turnover and hypertrophy‐associated gene expression. P4H inhibition could therefore be of value in treatment of myocardial remodelling accompanying pressure overload hypertrophy.
Dynamic exploration and editing of KEGG pathway diagrams
Authors: Klukas Christian , Schreiber Falk 
Published: December 2006

AbstractMotivation: The Kyoto Encyclopedia of Genes and Genomes (KEGG) Pathway database is a very valuable information resource for researchers in the fields of life sciences. It contains metabolic and regulatory processes in the form of wiring diagrams, which can be used for browsing and information retrieval as well as a base for modeling and simulation. Thus it helps in understanding biological processes and higher-order functions of biological systems.Currently the KEGG website uses semi-static visualizations for the presentation and navigation of its pathway information. While this visualization style offers a good pathway presentation and navigation, it does not provide some of the possibilities related to dynamic visualizations, most importantly, the creation and visualization of user-specific pathways.Results: This paper presents methods for the dynamic visualization, interactive navigation and editing of KEGG pathway diagrams. These diagrams, given as KEGG Markup Language (KGML) files, can be visually explored using novel approaches combining semi-static and dynamic visualization, but also edited or even newly created and then exported into KGML files.Availability: KGML-ED, a program implementing the presented methods, is available free of charge to the scientific community atContact: schreibe@ipk-gatersleben.de
How internal waves influence the vertical distribution of zooplankton
Authors: RINKE KARSTEN , HÜBNER INA , PETZOLDT THOMAS , ROLINSKI SUSANNE , KÖNIG‐RINKE MARIE , POST JOHANNES , LORKE ANDREAS , BENNDORF JÜRGEN 
Published: December 2006

Summary1. We present data with a high spatio‐temporal resolution from a 72‐h field survey in Bautzen Reservoir (Saxony, Germany). The aims of this survey were to observe hydrophysical processes during a period of unstable stratification in spring and investigate the effect of wind‐induced internal waves on the vertical distribution of zooplankton.2. Wind velocities up to 10 m s−1 caused a strong downwelling event of warm water at the sampling site and led to the generation of internal waves with an amplitude of 4 m.3. The zooplankton community, which was dominated by Daphnia galeata, inhabited epilimnetic waters. Downwelling enlarged the thickness of the epilimnetic layer and, hence, led to high zooplankton abundances down to relatively deep water strata indicating lateral transport of zooplankton. As a consequence, area‐specific zooplankton abundances increased considerably (max. fourfold) during downwelling.4. We conclude that classical limnological field sampling, such as for monitoring purposes, can lead to severely biased estimates of zooplankton abundance due to the interfering effects of hydrophysical processes like internal waves.5. Backscattering strengths measured by a simultaneously deployed Acoustic Doppler Current Profiler (600 kHz) were found to be correlated with estimated zooplankton abundances based on plankton samples.
Detection and visualization of spatial genetic structure in continuous Eucalyptus globulus forest
Authors: JONES TIM H. , VAILLANCOURT RENÉ E. , POTTS BRAD M. 
Published: December 2006

AbstractVisualizing the pattern of variation using microsatellites within a Eucalyptus globulus forest on the island of Tasmania provided surprising insights into the complex nature of the fine‐scale spatial genetic structure that resides in these forests. We used spatial autocorrelation and principal coordinate analysis to compare fine‐scale genetic structure between juvenile and mature cohorts in a study area, 140 m in diameter, located within a typical, continuous E. globulus forest. In total, 115 juvenile and 168 mature individuals were genotyped with eight highly polymorphic microsatellite loci. There was no significant difference in the level of genetic diversity between cohorts. However, there were differences in the spatial distribution of the genetic variation. Autocorrelation analysis provided clear evidence for significant spatial genetic structure in the mature cohort and significant, but weaker, structure in the juvenile cohort. The spatial interpolation of principal coordinate axes, derived from ordination of the genetic distance matrix between individuals, revealed a spatially coherent family group which was evident in both cohorts. Direct comparison of the genetic structure within each cohort allowed visualization of a shift in the spatial distribution of genetic variation within the population of approximately 10 m. As the shift coincided with the direction of prevailing winds, it is hypothesized that this phenomenon is due to downwind dispersal of seeds and is indicative of the important role of prevailing winds in forcing eastward gene flow in these high‐latitude forests.
Cytoskeletal protein P41 is required to anchor the terminal organelle of the wall‐less prokaryote Mycoplasma pneumoniae
Authors: Hasselbring Benjamin M. , Krause Duncan C. 
Published: December 2006

SummaryThe cell wall‐less prokaryote Mycoplasma pneumoniae approaches the minimal requirements for a cell yet produces a complex terminal organelle that mediates cytadherence and gliding motility. Here we explored the molecular nature of the M. pneumoniae gliding machinery, utilizing fluorescent protein fusions and digital microcinematography to characterize gliding‐altered mutants having transposon insertions in MPN311, encoding the cytoskeletal protein P41. Disruption of MPN311 resulted in loss of P41 and P24, the downstream gene product. Gliding ceases in wild‐type M. pneumoniae during terminal organelle development, which occurs at the cell poles adjacent to an existing structure. In contrast, terminal organelle development in MPN311 mutants did not necessarily coincide with gliding cessation, and new terminal organelles frequently formed at lateral sites. Furthermore, new terminal organelles exhibited gliding capacity quickly, unlike wild‐type M. pneumoniae. P41 and P24 localize at the base of the terminal organelle; in their absence this structure detached from the cell body of motile and dividing cells but retained gliding capacity and thus constitutes the gliding apparatus. Recombinant wild‐type P41 restored cell integrity, establishing a role for this protein in anchoring the terminal organelle to the cell body.
Recombination is suppressed and variability reduced in a nascent Y chromosome
Authors: BERSET‐BRÄNDLI L. , JAQUIÉRY J. , PERRIN N. 
Published: December 2006

AbstractSeveral hypotheses have been elaborated to account for the evolutionary decay commonly observed in full‐fledged Y chromosomes. Enhanced drift, background selection and selective sweeps, which are expected to result from reduced recombination, may all share responsibilities in the initial decay of proto‐Y chromosomes, but little empirical information has been gathered so far. Here we take advantage of three markers that amplify on both of the morphologically undifferentiated sex chromosomes of the European tree frog (Hyla arborea) to show that recombination is suppressed in males (the heterogametic sex) but not in females. Accordingly, genetic variability is reduced on the Y, but in a way that can be accounted for by merely the number of chromosome copies per breeding pair, without the need to invoke background selection or selective sweeps.
The role of environment and mid‐domain effect on moth species richness along a tropical elevational gradient
Authors: Brehm Gunnar , Colwell Robert K. , Kluge Jürgen 
Published: December 2006

ABSTRACTAim  The biodiversity of geometrid moths (Lepidoptera) along a complete tropical elevational gradient was studied for the first time. The patterns are described, and the role of geometric constraints and environmental factors is explored.Location  The study was carried out along the Barva Transect (10° N, 84° W), a complete elevational gradient ranging from 40 to 2730 m a.s.l. in Braulio Carrillo National Park, Costa Rica, and adjacent areas.Methods  Moths were sampled manually in 2003 and 2004 at 12 rain forest sites using light ‘towers’, each with two 15 W ultraviolet fluorescent tubes. We used abundance‐based rarefaction, statistical estimation of true richness (Chao 1), geographically interpolated observed richness and Fisher's alpha as measures of local diversity.Results   A total of 13,765 specimens representing 739 species were analysed. All four measures showed a hump‐shaped pattern with maxima between 500 and 2100 m elevation. The two subfamilies showed richness and diversity maxima at either lower (Ennominae) or higher (Larentiinae) elevation than Geometridae as a whole. Among the four environmental factors tested, relative humidity yielded the highest correlation over the transect with the rarefaction‐based richness estimates as well as with estimated true species richness of Geometridae as a whole and of Larentiinae, while rainfall explained the greatest variation of Ennominae richness. The elevational pattern of moth richness was discordant with both temperature and with tree species richness. A combination of all environmental factors in a stepwise multiple regression produced high values of r2 in Geometridae. The potential effects of geometric constraints (mid‐domain effect, MDE) were investigated by comparing them with observed, interpolated richness. Overall, models fitted very well for Geometridae as a whole and for Ennominae, but less well for Larentiinae. Small‐ranged species showed stronger deviations from model predictions than large‐ranged species, and differed strikingly between the two subfamilies, suggesting that environmental factors play a more pronounced role for small‐ranged species. We hypothesize that small‐ranged species (at least of the Ennominae) may tend to be host specialists, whereas large‐ranged species tend to be polyphagous. Based on interpolated ranges, mean elevational range for these moths was larger with increasing elevation, in accordance with Rapoport's elevational rule, although sampling effects may have exaggerated this pattern. The underlying mechanism remains unknown because Rapoport's ‘rescue’ hypothesis could not explain the observed pattern.Conclusions  The results clearly show that moth diversity shows a hump‐shaped pattern. However, remarkable variation exists with regard to taxon and range size. Both environmental and geometric factors are likely to contribute to the observed patterns.