Genetic dissection of corticosteroid receptor function in mice

Functional genomic technologies, including artificial chromosome-based transgenesis and conditional gene targeting, allowed us to generate mouse models harboring genes with loss-of-function mutations, gain-of-function mutations, spatially and/or temporally restricted mutations, tissue-specific mutations, and function-selective mutations. This kind of "allelic series" for corticosteroid receptors in mouse models provides a very useful resource for the molecular understanding of corticosteroid function in vivo. These models will also support the identification of steroid receptor target genes in order to define a steroid signaling cascade in molecular terms. They provide opportunities for the identification of compounds that regulate steroid receptors in a tissue-specific and function-selective manner. For example, selective glucocorticoid receptor modulators preventing receptor dimerization and DNA binding can be expected to reduce osteoporotic and/or diabetogenic side effects, but to display partial or full anti-inflammatory potential. Thus, these mouse models will help to evaluate distinct steroid receptor functions for therapeutic intervention.

Determination of transport parameters in air-saturated porous materials via reflected ultrasonic waves

An ultrasonic reflectivity method of evaluating the acoustic parameters of porous materials saturated by air (or any other gas) is discussed. The method is based on experimental detection of waves reflected at normal incidence by the first and second interface of the material. This method is based on a temporal model of direct and inverse scattering problems for the propagation of transient ultrasonic waves in a homogeneous isotropic slab of porous material with a rigid frame [Fellah et al., J. Acoust. Soc. Am. 113, 61-73 (2003)]. Generally, the conventional ultrasonic approach can be used to determine tortuosity, and viscous and thermal characteristic lengths via transmitted waves. Porosity cannot be estimated in transmitted mode because of its very weak sensitivity. First interface use of the reflected wave at oblique incidence leads to the determination of porosity and tortuosity [Fellah et al., J. Acoust. Soc. Am. 113, 2424-2433 (2003)] but this is not possible at normal incidence. Using experimental data of reflected waves by the first and second interface at normal incidence simultaneously leads to the determination of porosity, tortuosity, viscous and thermal characteristic lengths. As with the classic ultrasonic approach for characterizing porous material saturated with one gas, both characteristic lengths are estimated individually by assuming a given ratio between them. Tests are performed using weakly resistive industrial plastic foams. Experimental and numerical results, and prospects are discussed.

Cytoskeletal 10 nm filaments in cells of the algal phyla Chlorophyta, Charophyta, and Chrysophyta and their developmentally regulated and species-specific association with prosomes

10 nm diameter filaments were observed in whole-mount preparations of algae of diverse phyla: Acetabularia acetabulum and A. major (Chlorophyta), Chara australis and Nitella flexilis (Charophyta), and Poterioochromonas malhamensis (Chrysophyta). A polyclonal antibody raised against a basic, 50 kDa DNA-binding protein of A. acetabulum stains the filaments of A. acetabulumand and A. major as well as of C. australis and N. flexilis. While in the perinuclear region of A. acetabulumand and A. major and throughout the cytoplasm of P. malhamensis the 10 nm filaments have a smooth appearance, in the stalk of A. acetabulumand and A. major they are densely covered by globular structures; in C. australis and N. flexilis they are less frequently associated with such material. The morphology of a part of the globular particles is quite reminiscent of prosomes. A monoclonal antibody elicited against prosomes isolated from A. acetabulum indeed decorates the globular particles on the A. acetabulum and A. major filaments. The possible role of these filament-particle associations is discussed.

Measuring the porosity and the tortuosity of porous materials via reflected waves at oblique incidence

An ultrasonic reflectivity method is proposed for measuring porosity and tortuosity of porous materials having a rigid frame. Porosity is the relative fraction by volume of the air contained within a material. Tortuosity is a geometrical parameter which intervenes in the description of the inertial effects between the fluid filled the porous material and its structure at high frequency range. It is generally easy to evaluate the tortuosity from transmitted waves, this is not the case for porosity because of its weak sensitivity in transmitted mode. The proposed method is based on measurement of reflected wave by the first interface of a slab of rigid porous material. This method is obtained from a temporal model of the direct and inverse scattering problems for the propagation of transient ultrasonic waves in a homogeneous isotropic slab of porous material having a rigid frame [Z. E. A. Fellah, M. Fellah, W. Lauriks, and C. Depollier, J. Acoust. Soc. Am. 113, 61 (2003)]. Reflection and transmission scattering operators for a slab of porous material are derived from the responses of the medium to an incident acoustic pulse at oblique incidence. The porosity and tortuosity are determined simultaneously from the measurements of reflected waves at two oblique incidence angles. Experimental and numerical validation results of this method are presented.

Novel mode of hormone induction of tandem tomato invertase genes in floral tissues

The genomic organization of two extracellular invertase genes from tomato (Lin5 and Lin7), which are linked in a direct tandem repeat, and their tissue-specific and hormone-inducible expression are shown. Transient expression analysis of Lin5 promoter sequences fused to the beta-glucuronidase (GUS) reporter gene (uidA) demonstrates a specific expression of Lin5 during tomato fruit development. A Lin5 promoter fragment was fused to the truncated nos promoter to analyse hormone induction via GUS reporter gene activity in transiently transformed tobacco leaves. A specific up-regulation of GUS activity conferred by this Lin5 promoter fragment in response to gibberellic acid (GA), auxin and abscisic acid (ABA) treatment was observed, indicating a critical role of the regulation of Lin5 by phytohormones in tomato flower and fruit development. In situ hybridization analysis of Lin7 shows a high tissue-specific expression in tapetum and pollen. These results support an important role for Lin5 and Lin7 extracellular invertases in the development of reproductive organs in tomato and contribute to unravel the underlying regulatory mechanisms.

Scanning-force techniques to monitor time-dependent changes in topography and adhesion force of proteins on surfaces

Scanning-force microscopy (SFM) investigations were conducted to probe the influences of the interactions of proteins with surfaces relevant in medicine. These interactions are an important feature in the area of biofilm formation. The adsorption of proteins leads to changes in topography, which was monitored for the build up of protein layers of hen egg-white lysozyme and bovine serum albumin (BSA) on mica in real time in phosphate-buffered aqueous solution over a time period of 10 min. Phase imaging was additionally applied to compare material contrasts and to evaluate this method for further application in this field. The adhesion forces that develop on a time scale below 20 s between a protein-modified SFM tip and titanium surfaces (TiO(2), TiAl6V4 and TiAl6Nb7) were investigated. The influences of the parameters loading force and interaction time between the protein and the surface were monitored as well as the influence of protein structure. The interaction time dependency of the adhesion force could be described with a kinetic model of two consecutive first-order reactions. For the maximal adhesion force a correlation to the ratio of the amino acids cysteine, proline and glycine has been proposed.

Multiparameter single-molecule fluorescence spectroscopy reveals heterogeneity of HIV-1 reverse transcriptase:primer/template complexes

By using single-molecule multiparameter fluorescence detection, fluorescence resonance energy transfer experiments, and newly developed data analysis methods, this study demonstrates directly the existence of three structurally distinct forms of reverse transcriptase (RT):nucleic acid complexes in solution. Single-molecule multiparameter fluorescence detection also provides first information on the structure of a complex not observed by x-ray crystallography. This species did not incorporate nucleotides and is structurally distinct from the other two observed species. We determined that the nucleic acid substrate is bound at a site far removed from the nucleic acid-binding tract observed by crystallography. In contrast, the other two states are identified as being similar to the x-ray crystal structure and represent distinct enzymatically productive stages in DNA polymerization. These species differ by only a 5-A shift in the position of the nucleic acid. Addition of nucleoside triphosphate or of inorganic pyrophosphate allowed us to assign them as the educt and product state in the polymerization reaction cycle; i.e., the educt state is a complex in which the nucleic acid is positioned to allow nucleotide incorporation. The second RT:nucleic acid complex is the product state, which is formed immediately after nucleotide incorporation, but before RT translates to the next nucleotide.

A glutamate mutase is involved in the biosynthesis of the lipopeptide antibiotic friulimicin in Actinoplanes friuliensis

Actinoplanes friuliensis produces the lipopeptide antibiotic friulimicin. This antibiotic is active against gram-positive bacteria such as multiresistant Enterococcus and Staphylococcus strains. It consists of 10 amino acids that form a ring structure and 1 exocyclic amino acid to which an acyl residue is attached. By a reverse genetic approach, biosynthetic genes were identified that are required for the nonribosomal synthesis of the antibiotic. In close proximity two genes (glmA and glmB) were found which are involved in the production of methylaspartate, one of the amino acids of the peptide core. Methylaspartate is synthesized by a glutamate mutase mechanism, which was up to now only described for glutamate fermentation in Clostridium sp. or members of the family ENTEROBACTERIACEAE: The active enzyme consists of two subunits, and the corresponding genes overlap each other. To demonstrate enzyme activity in a heterologous host, it was necessary to genetically fuse glmA and glmB. The resulting gene was overexpressed in Streptomyces lividans, and the fusion protein was purified in an active form. For gene disruption mutagenesis, a host-vector system was established which enables genetic manipulation of Actinoplanes spp. for the first time. Thus, targeted inactivation of biosynthetic genes was possible, and their involvement in friulimicin biosynthesis was demonstrated.

Genetic dissection of gluco- and mineralocorticoid receptor function in mice

Nuclear hormone receptors function to transduce hormonal signals into transcriptional responses by controlling the activity of specific target genes. These target genes comprise a genetic network whose coordinate activity defines the physiological responses to hormonal signals. Dissecting nuclear hormone receptor functions in vivo by gene inactivation and transgenic strategies represents an invaluable and powerful approach to increase our knowledge of these genetic networks and their physiological functions. Glucocorticoids and mineralocorticoids are involved in numerous physiological processes important to maintain metabolic, cardiovascular, central nervous, and immune system homeostasis. Germline and somatic gene targeting as well as an increased dosage of the glucocorticoid receptor (GR) allows the characterization of the various functions and molecular modes of action of this receptor. Most of the effects of the GR are mediated via activation and repression of gene expression. To separate activating from repressing functions of the GR, a point mutation was introduced which allowed us to characterize and distinguish functions dependent on GR binding to DNA from those mediated by protein/protein interaction. Cell/tissue-specific mutations of the gluco- and mineralocorticoid receptor is the basis for the evaluation of their cell-specific functions, including the characterization of target genes of the receptors in order to describe their specific effects on different targets.

[Health - oriented aspects in nutrition of children and adolescents]

The author underlines the necessity of recognition health-oriented aspects in nutrition of children and adolescents for both food producers as well as consumers. It is of great importance not only for growth and development of the young population but also for the health of adults. The author has presented the concept of interrelationship between factors aimed at achieving safe food and proper nutritional guidelines for consumer and the knowledge of genetic and environmental aspects. Educational programmes and research in the field of safe food and proper nutrition sciences should play a crucial role.

The clinical relevance of non-classified dysganglionoses and implications for a new grading system

In addition to the classified types of dysganglionosis, certain non-classified dysganglionoses (NCD) (types 1-4) were introduced by Meier-Ruge in 1992. Clinical data on these conditions are limited. Among 134 children with intestinal dysganglionoses (ID) treated from 1979 to 1999, 12 were identified to have a NCD. Their clinical course is presented. The existence of mild ID (type 1) is difficult to demonstrate. Current definitions and data on clinical relevance are not convincing. An indication for surgical treatment is not present. Isolated hypogenesis of the submucous plexus (SMP) (type 2, n = 8) is clinically a more severe kind of intestinal neuronal dysplasia type B and often requires early surgical intervention, but not resection. When associated with aganglionosis, its recognition is important for surgical strategy, to avoid complicated clinical courses, which are frequent if total or nearly-total resection is not performed. Hypogenesis of the myenteric plexus (MP) (type 5, n = 1) has received little attention so far. The sporadic appearance of heterotopic nerve cells of the SMP in the mucosa (type 3, n = 1) is physiologic; clusters of such cells, however, are probably of pathologic value, especially in combination with other types of ID in the same patient. Heterotopic nerve cells of the MP (type 4, n = 3) in the circular and longitudinal muscle layers are highly pathologic. This clearly-defined type is of major clinical relevance and requires complete resection. A severe disturbance of the migration process is the underlying cause. To simplify the terminology of IDs, a grading system based on the anatomic structures and clinical findings is proposed: innervation disturbances of the mucosa (grade I) are of limited clinical significance. Isolated malformations of the SMP (grade II) may require an enterostomy, but do not require resection except in certain cases associated with distal aganglionosis. Dysganglionosis of the MP (grade III) usually exhibits more severe symptoms and resection is indicated, especially with associated hypo- or aganglionosis. In aganglionic bowel (grade IV) resection is mandatory.

Characterization and regulation of a CHO cell line stably expressing human serotonin N-acetyltransferase (EC 2.3.1.87)

Current melatonin research is essentially based on the finding of new molecular tools, including synthetic or natural agonists and antagonists for the melatonin receptors and synthetic inhibitors of the enzymes involved in its biosynthesis. Indeed, the use of these compounds will improve our understanding of some of the numerous mechanisms of action of melatonin. The present report deals with the establishment and description of a new cell line expressing in a stable manner human arylalkylamine-N-acetyltransferase (AANAT, E.C.2.3.1.87). This new cellular system permits one to check the capacity of newly discovered inhibitors to penetrate the cell and reach their target. Some emphasis is put on inhibitors of the bromoacetyltryptamine family since these precursor compounds form in situ bisubstrate inhibitors with strong affinity for the human enzyme. AANAT is known to undergo complex and rapid regulation by a subtle balance between extremely fast catabolism and protection against it, both due to serine phosphorylation. In the present report, this phosphorylation is shown to occur in vitro after incubation with several kinases (rho-kinase, chk-1, protein kinase A) but not with protein kinase C. Phosphorylation enhances the specific activity of the enzyme by a factor of two to five. This phosphorylation is also shown to occur after treatment of the cell with compounds such as forskolin and rolipram that enhance or protect the intracellular pool of cAMP or the cell-permeable cAMP analogue, dioctanoyl-cAMP. The specificity of the cellular model was assessed using a series of substrates and inhibitors of AANAT already described in the literature, and the characteristics of this cellular system are shown to correspond with those reported for the purified enzyme. This cell line was used to screen libraries of compounds in a living system and led to the discovery of several potent specific and non-toxic AANAT inhibitors.

Solvation phenomena of a tetrapeptide in water/trifluoroethanol and water/ethanol mixtures: a diffusion NMR, intermolecular NOE, and molecular dynamics study

Solvation of a tetrapeptide, NAc-Ser-Phe-Val-Gly-OMe (1), in water and in water/alcohol mixtures with 2,2,2-trifluoroethanol (TFE)/water or ethanol (ETH)/water has been studied by diffusion NMR and intermolecular NOE measurements. The experimental results were compared with those obtained from detailed Molecular Dynamics (MD) calculations. Independently, all three methods revealed preferential solvation on the surface of the peptide by TFE in the water/TFE mixtures, but not by ETH in the water/ETH mixtures. The MD calculations show that the TFE concentration coating the peptide is higher than that in the bulk, while for ethanol, the concentration is nearly equal to that in the bulk. Calculated site-specific preferential solvation data between TFE, ETH, and water with the different peptide groups have been compared with the NMR data and shown to be in general agreement with the experimental facts.

Quantitative structure-activity relationships for the toxicity of nitrobenzenes to Tetrahymena thermophila

In this study IGC50 (50% inhibitory growth concentration) values of 26 nitrobenzenes were determined for population growth endpoint of Tetrahymena thermophila. The toxicity order of the observed compounds has been found as follows: dinitro compounds > mono-nitro compounds; dichloronitrobenzenes > monochloronitrobenzenes; and meta-substituted nitrobenzenes > ortho-/para-substituted nitrobenzenes (NT, NPh, NAnis) except for the dinitrobenzenes and nitroanilines (DNB, NAn). Quantitative structure activity relationships (QSARs) were developed using log of the inverse of the IGC50 (logIGC50(-1)) in mole liter as the dependent variable and six molecular descriptors--logP, 1X(V), I, K alpha, sigma sigma- and E(LUMO) as the independent variables. Through multiplicate regression analysis, one best equation was obtained: log IGC50(-1) = 2.93 + 0.830sigma sigma- + 0.350I, n = 26, r = 0.923, r2 = 0.852, s = 0.265, f = 66.4 The equation was used to estimate IGC50 for seven analogues.

Dielectric properties of KDP filled porous alumina nanocomposite thin films

A new concept of a composite dielectric thin film fabrication is presented. The fabrication process consists of two stages. The first stage is anodizing a thin aluminum film to produce a porous alumina film that contains an array of nanometer sized parallel pores. The second stage is filling the pores with a saturated KDP (KH2PO4) liquid solution due to capillary forces. After drying KDP nanocrystals are formed inside the pores. This process results in a formation of a composite dielectric thin film composed of the alumina pores walls as one dielectric material and the KDP nanocrystals inside the pores as another dielectric material. The dielectric permittivity of this composite film is higher than that of the porous alumina film at all applied frequencies. The dielectric enhancement is more pronounced at low frequencies due to an interface polarization mechanism. This fabrication process enables controlling the size, composition, and microstructure of the composite dielectric film constituents and thus changing its dielectric properties over a wide range of values.

Enrichment of spreadable fats with polyunsaturated fatty acids omega-3 using fish oil

Polyunsaturated fatty acids of the omega-3 series, especially very long chain--eicosapenta- and docosahexaenoic acid (EPA, DHA)--exert a strongly desirable influence on health. However, their intake with the western-style diet is usually too low which favours development of many diseases (CVD, cancers, allergies, etc.). Nowadays elevation of EPA and DHA intake is commonly recommended, but almost the only dietary source of them is seafoods, especially fish. A new way to increase the intake of long-chain omega-3 without radical changes of eating patterns is enrichment of regularly consumed foods with unhydrogenated fish oil. The aim of this study was to establish sensory and nutritionally acceptable enrichment level of low-calorie spreadable fats (soft margarine and mix of butter and vegetable oil) with EPA and DHA by addition of fish oil preparations (ROPUFA--30% EPA, DHA and MARITEX--10%), and evaluation of the stability of enriched spreads during storage (sensory and chemical). It was shown that tested spreadable fats might be enriched up to 1% EPA, DHA (i.e. 3% ROPUFA, 8% MARITEX), and that this had no significant influence on sensory acceptability. Both used fish oils which exerted similar influence on the quality of fats. An enriched mix of butter and vegetable oil and margarine may be stored up to 3 and 6 weeks respectively without significant decrease of quality. Peroxide value and acid numbers were not much affected by enrichment and storage. Daily portion (25-30 g/day) of spreadable fats enriched on the level established in the study may provide 0.2-0.3 g EPA, DHA, significantly increasing the amount of long-chain omega-3 in the diet above those eaten normally.

Detection of firearm imprints on the hands of suspects: effectiveness of PDT reaction

Pyridyldiphenyl triazine (PDT) and three of its analogues were compared as practical reagents for visualizing unseen impressions left on the hands of a person who has held a firearm. The parent compound, PDT, gave the best results using intensity and clarity as measuring criteria. The effectiveness of the PDT reaction was then studied on 147 volunteers who had held firearms in their hands. Identifiable impressions of the metallic parts of the weapons were developed on the hands of 103 volunteers (70%). Results with females were slightly higher than with males, however, the difference was possibly statistically insignificant, and needs further study. Ferroprint and Ferrotrace, 5 commercial preparations that are based on the PDT reaction, have become a part of the professional equipment of every crime scene technician in Israel.

Induction of the epithelial Na+ channel via glucocorticoids in mineralocorticoid receptor knockout mice

Epithelial Na+ channel (ENaC) activity in kidney and colon is stimulated by aldosterone acting on the mineralocorticoid receptor (MR). MR and the glucocorticoid receptor (GR) show high homology in their DNA-binding domain and have similar affinities to mineralo- and glucocorticoids. We therefore asked whether the glucocorticoid-mediated activation of ENaC is restricted to the presence of MR and used the MR knockout mouse model to address this question. Due to their MR deficiency and the consecutive reduction of ENaC activity these mice die as neonates, and even after appropriate substitution therapy adult MR knockout mice suffer from high Na+ loss and hyperkalemia. In the present study, glucocorticoid treatment restored plasma K+ and almost normalized the fractional excretions of Na+ (FENa+) and K+ (FEK+) in adult salt-substituted MR knockout mice, while the effect of amiloride on FENa+ and FEK+ was augmented in these animals. In order to estimate ENaC activity, measurements of transepithelial equivalent short-circuit current (Isc) were performed. Glucocorticoids induced an amiloride-sensitive Na+ absorption in renal cortical collecting duct and distal colon of MR-/- of about 25% and 50% of the currents observed in glucocorticoid-treated wild-type mice, respectively. In the colon glucocorticoid treatment increased the mRNA abundance of all three ENaC subunits, in the kidney only alpha-ENaC was increased. The regulation of ENaC expression was the same in both genotypes and thus irrespective of the presence of MR. These data show that MR is no prerequisite for the activation of ENaC transcription and activity, and that the respective mechanisms can be stimulated via GR.

The macrophage-induced gene (mig) of Mycobacterium avium encodes a medium-chain acyl-coenzyme A synthetase

The macrophage-induced gene (mig) of Mycobacterium avium has been associated with virulence, but the functions of the gene product were still unknown. Here we have characterized the Mig protein by biochemical methods. A plasmid with a histidine-tagged fusion protein was constructed for expression in Escherichia coli. Mig was detected as a 60 kDa protein after expression and purification of the recombinant gene product. The sequence of the fusion gene and of the parent gene in M. avium were reexamined. This confirmed that the mig gene encodes a 550 amino acid protein (58 kDa) instead of a 295 amino acid protein (30 kDa) as predicted before. The 550 amino acid Mig exhibits a high degree of homology to bacterial acyl-CoA synthetases. Two artificial 30 kDa derivatives of Mig were expressed and purified as histidine-tagged fusion proteins in E. coli. These proteins and the 58.6 kDa histidine-tagged Mig protein were analysed for activity with an acyl-CoA synthetase assay. Among the three investigated proteins, only the 58.6 kDa Mig exhibited detectable activity as an acyl-CoA synthetase (EC 6.2.1.3) with saturated medium-chain fatty acids, unsaturated long-chain fatty acid and some aromatic carbon acids as substrates. Enzymatic activity could be inhibited by 2-hydroxydodecanoic acid, a typical inhibitor of medium-chain acyl-CoA synthetases. We postulate a novel medium-chain acyl-CoA synthetase motif. We have investigated the biochemical properties of Mig and suggest that this enzyme is involved in the metabolism of fatty acid during mycobacterial survival in macrophages.

Enzymatic and non-enzymatic lipid peroxidation in leaf development

Enzymatic and non-enzymatic lipid peroxidation has been implicated in programmed cell death, which is a major process of leaf senescence. To test this hypothesis we developed a high-performance liquid chromatography (HPLC) method for a simultaneous analysis of the major hydro(pero)xy polyenoic fatty acids. Quantities of lipid peroxidation products in leaves of different stages of development including natural senescence indicated a strong increase in the level of oxygenated polyenoic fatty acids (PUFAs) during the late stages of leaf senescence. Comprehensive structural elucidation of the oxygenation products by means of HPLC, gas chromatography/mass spectrometry and (1)H nuclear magnetic resonance suggested a non-enzymatic origin. However, in some cases a small share of specifically oxidized PUFAs was identified suggesting involvement of lipid peroxidizing enzymes. To inspect the possible role of enzymatic lipid peroxidation in leaf senescence, we analyzed the abundance of lipoxygenases (LOXs) in rosette leaves of Arabidopsis. LOXs and their product (9Z,11E,13S,15Z)-13-hydroperoxy-9,11,15-octadecatrienoic acid were exclusively detected in young green leaves. In contrast, in senescing leaves the specific LOX products were overlaid by large amounts of stereo-random lipid peroxidation products originating from non-enzymatic oxidation. These data indicate a limited contribution of LOXs to total lipid peroxidation, and a dominant role of non-enzymatic lipid peroxidation in late stages of leaf development.