A2 A3 Research Articles

The mouse lpA3/ Edg7 lysophosphatidic acid receptor gene: genomic structure, chromosomal localization, and expression pattern

The extracellular signaling molecule, lysophosphatidic acid (LPA), mediates proliferative and morphological effects on cells and has been proposed to be involved in several biological processes including neuronal development, wound healing, and cancer progression. Three mammalian G protein-coupled receptors, encoded by genes designated lp (lysophospholipid) receptor or edg (endothelial differentiation gene), mediate the effects of LPA, activating similar (e.g. Ca 2+ release) as well as distinct (neurite retraction) responses. To understand the evolution and function of LPA receptor genes, we characterized lp A3/ Edg7 in mouse and human and compared the expression pattern with the other two known LPA receptor genes ( lp A1/ Edg2 and lp A2/ Edg4non-mutant). We found mouse and human lp A3 to have nearly identical three-exon genomic structures, with introns upstream of the coding region for transmembrane domain (TMD) I and within the coding region for TMD VI. This structure is similar to lp A1 and lp A2, indicating a common ancestral gene with two introns. We localized mouse lp A3 to distal Chromosome 3 near the varitint waddler ( Va) gene, in a region syntenic with the human lp A3 chromosomal location (1p22.3-31.1). We found highest expression levels of each of the three LPA receptor genes in adult mouse testes, relatively high expression levels of lp A2 and lp A3 in kidney, and moderate expression of lp A2 and lp A3 in lung. All lp A transcripts were expressed during brain development, with lp A1 and lp A2 transcripts expressed during the embryonic neurogenic period, and lp A3 transcript during the early postnatal period. Our results indicate both overlapping as well as distinct functions of lp A1, lp A2, and lp A3.

The LPA receptors

Lysophosphatidic acid (LPA) is a growth factor-like lipid that produces many cellular responses. These responses, including actin cytoskeletal rearrangements, cell proliferation and inhibition of gap junction communication, have been documented in many cell types over the last 2 decades. Both non-receptor and receptor-mediated mechanisms had been implicated to explain these responses. A clear advance in this field was the cloning and functional identification of LPA receptors, and there are currently three high-affinity members, LP A1, LP A2 and LP A3 (synonymous with orphan receptor names edg-2, edg-4 and edg-7, respectively). Here we review the gene structure, expression and functions of LPA receptors. We also discuss the in vivo roles mediated by a single LPA receptor type, based on studies of the nervous system, a major locus of LPA receptor expression.

Structure and chromosome location of Smtn, the mouse smoothelin gene

Smoothelins are cytoskeleton-associated proteins that are found in contractile smooth muscle. Two isoforms have been identified: smoothelin-A, expressed in visceral tissues and smoothelin-B, found in vascular tissues. The mouse smoothelin gene (Smtn) was isolated and characterized. It was assigned to chromosome 11 band A2–A3 by fluorescence in situ hybridization. The gene consists of 20 exons and spans 23 kb. Its structure is conserved between mouse and human. The proximal promoter of both smoothelin-A and smoothelin-B contains several transcription factor-binding sites but lacks a consensus TATA box.

Some factors that determine proton conductivity in nonstoichiometric complex perovskites

Complex perovskites, of the types A2(B′B″)O6 and A3(B′B2″)O9, (in which A ions are always 2+, B′ ions are 3+ and 2+, respectively, and B″ ions are 5+), can become good high-temperature protonic conductors when they are made nonstoichiometric by increasing the concentration of the B′ ions at the expense of the B″ ions. After heating in water vapor, uptake of H2O occurs, and protons enter the structure. We consider the effects of several variables on the bulk ionic conductivity and activation energy for protonic conduction, including degree of nonstoichiometry, the effect of ordering on the B-sites, the effect of varying the radius of the B′ ion and the effect of changing the A ion from Sr2+ to Ba2+. The results show that disorder favors a higher conductivity, that the degree of order can change with nonstoichiometry, and that Ba compounds always have higher conductivity and lower activation energy than the corresponding Sr compounds.

Differential effects of adenosine receptor subtypes on release and reuptake of hippocampal serotonin.

To clarify the effects of adenosine receptor subtypes (A1, A2 and A3) on hippocampal serotonin (5-HT) release and 5-HT reuptake activity, hippocampal extracellular 5-HT levels were determined in vivo by microdialysis in freely moving rats. Selective 5-HT reuptake inhibitor (SSRI) fluoxetine and DU24565 increased extracellular 5-HT levels. Adenosine and A1 receptor agonist, 2-chloro-N6-cyclopentyl-adenosine (CCPA), decreased extracellular 5-HT levels, whereas non-selective antagonist, caffeine, and A1 antagonist, 8-cyclopentyl-1,3-dimethylxanthine (CPT) increased them. When 5-HT reuptake activity was inhibited by DU24565 and fluoxetine, the effects of CPT and CCPA on 5-HT level were enhanced. A2A receptor agonist, CGS21680, A2 receptor agonist, PD125944, A2 receptor antagonist, 3,7-dimethyl-1-propargylxanthine (DMPX), and A3 receptor agonist, N6-2-(4-aminophenyl)ethyladenosine (APNEA) did not affect 5-HT levels; however, when A1 receptor was blocked by CPT, 5-HT levels were increased by adenosine, CGS21680 and PD125944, and decreased by DMPX and APNEA. Under conditions of A1 receptor blockade, pretreatment with DU24565 or fluoxetine, enhanced the stimulatory effects of CGS21680 and PD125944 as well as inhibitory effects of DMPX on 5-HT level, whereas the inhibitory effect of APNEA was abolished. These results indicate that the stimulatory effects of A2 receptor and inhibitory effects of A3 receptor on hippocampal extracellular 5-HT levels are masked or abolished by the inhibitory effects of A1 receptor. In addition, hippocampal serotonergic transmission might be modulated by hippocampal presynaptic adenosine receptor subtypes, and hippocampal 5-HT reuptake activity might be modulated by hippocampal A3 receptor.

Three-dimensional structure of the ion-channel forming peptide trichorzianin TA VII bound to sodium dodecyl sulfate micelles.

Trichorzianin TA VII, Ac0 U1 A2 A3 U4 J5 Q6 U7 U8 U9 S10 L11 U12 P13 V14 U15 I16 Q17 Q18 Fol19, is a nonadecapeptide member of the peptaibol antibiotics biosynthesized by Trichoderma soil fungi, which is characterized by a high proportion of the alpha, alpha-dialkylated amino acids, alpha-aminoisobutyric acid (Aib, U) and isovaline (Iva, J), an acetylated N-terminus and a C-terminal phenylalaninol (Pheol, Fol). The main interest in such peptides stems from their ability to interact with phospholipid bilayers and form voltage-dependent transmembrane channels in planar lipid bilayers. In order to provide insights into the lipid-peptide interaction promoting the voltage gating, the conformational study of TA VII in the presence of perdeuterated sodium dodecyl sulfate (SDS-d25) micelles has been carried out. 1H sequential assignment have been performed with the use of two-dimensional homo- and -heteronuclear nmr techniques including double quantum filtered correlated spectroscopy, homonuclear Hartmann-Hahn, nuclear Overhauser effect spectroscopy, 1H-13C heteronuclear single quantum correlation, and heteronuclear multiple bond correlation. Conformational parameters, such as 3JNHC alpha H coupling constants, temperature coefficients of amide protons (delta gamma/delta TNH) and quantitative nuclear Overhauser enhancement data, lead to detailed structural information. Ninety-eight three-dimensional structures consistent with the nmr data were generated from 231 interproton distances six phi dihedral angle restraints, using restrained molecular dynamics and energy minimization calculations. The average rms deviation between the 98 refined structures and the energy-minimized average structure is 0.59 A for the backbone atoms. The structure of trichorzianin TA VII associated with SDS micelles, as determined by these methods, is characterized by two right-handed helical segments involving residues 1-8 and 11-19, linked by a beta-turn that leads to an angle about 90 degrees-100 degrees between the two helix axes; residues 18 and 19 at the end of the C-terminal helix exhibit multiple conformations.

Three‐dimensional structure of the ion‐chanel forming peptide trichorzianin TA VII bound to sodium dodecyl sulfate micelles

Trichorzianin TA VII, Ac0 U1 A2 A3 U4 J5 Q6 U7 U8 U9 S10 L11 U12 P13 V14 U15 I16 Q17 Q18 Fol19, is a nonadecapeptide member of the peptaibol antibiotics biosynthesized by Trichoderma soil fungi, which is characterized by a high proportion of the α,α-dialkylated amino acids, α-aminoisobutyric acid (Aib, U) and isovaline (Iva, J), an acetylated N-terminus and a C-terminal phenylalaninol (Pheol, Fol). The main interest in such peptides stems from their ability to interact with phospholipid bilayers and form voltage-dependent transmembrane channels in planar lipid bilayers. In order to provide insights into the lipid-peptide interaction promoting the voltage gating, the conformational study of TA VII in the presence of perdeuterated sodium dodecyl sulfate (SDS-d25) micelles has been carried out. 1H sequential assignments have been performed with the use of two-dimensional homo- and -heteronuclear nmr techniques including double quantum filtered correlated spectroscopy, homonuclear Hartmann-Hahn, nuclear Overhauser effect spectroscopy, 1H-13C heteronuclear single quantum correlation, and heteronuclear multiple bond correlation. Conformational parameters, such as 3JNHCαH coupling constants, temperature coefficients of amide protons (Δδ/ΔTNH) and quantitative nuclear Overhauser enhancement data, lead to detailed structural information. Ninety-eight three-dimensional structures consistent with the nmr data were generated from 231 interproton distances and six Φ dihedral angle restraints, using restrained molecular dynamics and energy minimization calculations. The average rms deviation between the 98 refined structures and the energy-minimized average structure is 0.59 Å for the backbone atoms. The structure of trichorzianin TA VII associated with SDS micelles, as determined by these methods, is characterized by two right-handed helical segments involving residues 1–8 and 11–19, linked by a β-turn that leads to an angle about 90°–100° between the two helix axes; residues 18 and 19 at the end of the C-terminal helix exhibit multiple conformations. © 1998 John Wiley & Sons, Inc. Biopoly 46: 75–88, 1998

Crystal structures of Toxoplasma gondii uracil phosphoribosyltransferase reveal the atomic basis of pyrimidine discrimination and prodrug binding.

Uracil phosphoribosyltransferase (UPRTase) catalyzes the transfer of a ribosyl phosphate group from alpha-D-5-phosphoribosyl-1-pyrophosphate to the N1 nitrogen of uracil. The UPRTase from the opportunistic pathogen Toxoplasma gondii is a rational target for antiparasitic drug design. To aid in structure-based drug design studies against toxoplasmosis, the crystal structures of the T.gondii apo UPRTase (1.93 A resolution), the UPRTase bound to its substrate, uracil (2.2 A resolution), its product, UMP (2.5 A resolution), and the prodrug, 5-fluorouracil (2.3 A resolution), have been determined. These structures reveal that UPRTase recognizes uracil through polypeptide backbone hydrogen bonds to the uracil exocyclic O2 and endocyclic N3 atoms and a backbone-water-exocyclic O4 oxygen hydrogen bond. This stereochemical arrangement and the architecture of the uracil-binding pocket reveal why cytosine and pyrimidines with exocyclic substituents at ring position 5 larger than fluorine, including thymine, cannot bind to the enzyme. Strikingly, the T. gondii UPRTase contains a 22 residue insertion within the conserved PRTase fold that forms an extended antiparallel beta-arm. Leu92, at the tip of this arm, functions to cap the active site of its dimer mate, thereby inhibiting the escape of the substrate-binding water molecule.

Lithium toxicity in yeast is due to the inhibition of RNA processing enzymes.

Hal2p is an enzyme that converts pAp (adenosine 3',5' bisphosphate), a product of sulfate assimilation, into 5' AMP and Pi. Overexpression of Hal2p confers lithium resistance in yeast, and its activity is inhibited by submillimolar amounts of Li+ in vitro. Here we report that pAp accumulation in HAL2 mutants inhibits the 5'-->3' exoribonucleases Xrn1p and Rat1p. Li+ treatment of a wild-type yeast strain also inhibits the exonucleases, as a result of pAp accumulation due to inhibition of Hal2p; 5' processing of the 5.8S rRNA and snoRNAs, degradation of pre-rRNA spacer fragments and mRNA turnover are inhibited. Lithium also inhibits the activity of RNase MRP by a mechanism which is not mediated by pAp. A mutation in the RNase MRP RNA confers Li+ hypersensitivity and is synthetically lethal with mutations in either HAL2 or XRN1. We propose that Li+ toxicity in yeast is due to synthetic lethality evoked between Xrn1p and RNase MRP. Similar mechanisms may contribute to the effects of Li+ on development and in human neurobiology.

Identities on Point-Line Figures in the Euclidean Plane

Introduction In [3] Larry Hoehn gave a proof of a theorem that is known as the Theorem of Pratt-Kasapi [1]. This note collects some ideas on how to generalize the theorem so that it holds not only for the pentagram but also for many other figures of the Euclidean plane and their duals. THEOREM 1. In a pentagrarn A1 A2 A3 A4 A5 with B1, B2, B3, B4, B5 as the points of intersection of its sides (FIGURE 1), the Pratt identity holds:

Optical Bistability and Multistability in the Linear Photorefractive Oscillator Accompanied by a Frequency Shift Due to Grating Motion

Abstract We investigate the bistable and multistable response of the phase conjugate reflectivity (PCR) for the case of a linear photorefractive (PR) oscillator in presence of the moving grating operation. Numerical evaluation of stable multiple solutions of the PCR shows enhancement, bistable, multistable and self-oscillating behaviours with respect to the control parameters like the frequency-shift (Ω) due to grating motion, reflectivities (M 1 and M 2) of cavity mirrors, the coupling strength (of complex gL and real g 0 L values) and the PR phase shift (φPR). If the different branches are assumed to be stable, multistable but isolated branching behaviour with an increased PCR can be predicted. Results are interpreted physically by considering the competitions between (i) the strengths of two moving transmission gratings that arise from A1–A4 (forward oscillating pump-incident) and A2–A3 (backward oscillating pump-phase conjugate) interferences and (ii) the applied frequency detuning that causes the gra...

Amino acid sequence of the bacteriophage T5 gene A2 protein

The complete amino acid sequence of the bacteriophage T5-encoded gene A2 protein was determined by protein sequencing. The 134-residue sequence is closely similar to that reported for the product of gene A2–A3 of bacteriophage BF23. Segments of the sequence are similar to segments of bacteriophage T4 gene 32 protein, bacteriophage T3 RNA polymerase, and the protein encoded by the host gene responsible for isoenzyme conversion of alkaline phosphatase. The similarity of residues 26–46 to a portion of a rabbit lipopolysaccharide binding protein is possibly relevant to the function of the A2 protein.

Third virial coefficient of polystyrene in benzene

AbstractSecond virial coefficients A2 and third virial coefficients A3 for benzene solutions of ten polystyrene fractions ranging in weight‐average molecular weight Mw from 104 to 2 × 107 at 25°C were determined by light scattering. The third coefficient is represented approximately by A3 = 8.0 × 10−6 M mol g−3 cm6 for Mw above 105. In this molecular weight region, the factor g defined by A3/AMw/ This trend of g is consistent with predictions of early two‐parameter theories but not with those of renormalization group theories. In particular, quantitative agreement is observed between the present experiments (for Mw ≳ 2 × 105) and the mean‐field two‐parameter theory of Stockmayer and Casassa.

Characterization of preearly genes in the terminal repetition of bacteriophage BF23 DNA by nucleotide sequencing and restriction mapping

A finer restriction map of the terminal repetition of bacteriophage BF23 DNA was determined and used to localize a 3.4-kbp deletion in the terminal repetition and to determine the physical location of preearly gene A2–A3. The nucleotide sequence of gene A2–A3 was determined and shown to code for a protein of 125 amino acids with no indication of a membrane transport sequence. The beginning of an adjacent gene, probably gene A1, was also sequenced.

Mapping of serotonin-like immunoreactivity in the ventral nerve cord of crayfish

Whole-mount immunohistochemical technique using antibody to serotonin (5-HT) had been used to map presumptive serotoninergic structures in the ventral abdominal and thoracic nerve cord of crayfish Procambarus clarkii. 5-HT immunoreactivity was detected in more than 30 cell bodies, numerous fibers and peripheral nerve endings of root plexus and neuropilar regions. Immunoreactive fibers are arranged in 3 pairs of rostrocaudal bundles. The median (MFB) and the lateral fiber bundles run longitudinally through the entire thoracic and abdominal nerve cord (first thoracic T1 to sixth abdominal A6 ganglia). The central (CFB) fiber bundles extend only from the subesophageal to the fourth thoracic ganglia. In the 4 anterior thoracic ganglia (T1-T4), two lateroposterior cell bodies send their major processes in the ipsilateral MFB. In the fifth thoracic (T5) and first abdominal (A1) ganglia, the pattern of reactive structures is similar. Two large anterior cells which send a single prominent process to join the ipsilateral MFB and 4 smaller posterior cells. In other abdominal ventral ganglia, immunoreactive structures are smaller and less labeled. Cell bodies are displayed in two kinds of arrangement giving the appearance of two distinct homogeneous groups of ganglia: an anterior group (A2-A3-A4) that contained two pairs of small neurons and a posterior group (A5-A6) that contained only a large unpaired medial neuron. These results were discussed in relation to the serotonin-like immunoreactivity pattern previously described in lobster by Beltz and Krawitz.

Enzyme-linked immunosorbent assay for detection ofPseudomonas aeruginosa H (Flagellar) antigen

An enzyme-linked immunosorbent assay (ELISA) with goat anti-rabbit IgG conjugated to peroxidase was used to test for the two antigen types of Pseudomonas aeruginosa: b (homogeneous) and a (heterogeneous) which contains the common subantigen (a0) and combinations of subtypes (a, a2 a3 a4). Preparations of b-type flagellar antigen could be distinguished from a-type by using b-adsorbed antisera titers as reciprocals of endpoint dilutions exceeding one million. Extracts from nonflagellated bacteria or purified lipopolysaccharides from the same strain were used as controls, which showed only background activity. Unknown flagellar antigen was determined using both isolated antigen preparations and formalin-killed bacterial cells. The ELISA procedure proved much more sensitive than the slide agglutination procedure: whereas nine of 18 strains tested did not react in the slide agglutination procedure all 18 strains were definitively typed as a or b strains with the ELISA. The ELISA also revealed the presence of a dominant, cross-reacting epitope (a0) in the heterogeneous a-type flagella using either isolated antigen or intact cells.

Saponin and sapogenol. XLII. Structures of acetyl-soyasaponins A1, A2, and A3, astringent partially acetylated bisdesmosides of soyasapogenol A, from american soybean, the seeds of Glycine max MERRILL.

By means of high performance liquid chromatography and other methods, three new partially acetylated soyasaponins, named acetyl-soyasaponin A1 (6a), acetyl-soyasaponin A2 (7a), and acetyl-soyasaponin A3 (8a), were isolated from American soybeans, the seeds of Glycine max MERRILL., together with hitherto known soyasaponins I (3), II (4), and III (5). Acetyl-soyasaponins A1, A2, and A3 are noteworthy due to their bitter and astringent tastes, although their parent saponins, soyasaponins A1 (6), A2 (7), and A3 (8), do not show such tastes.By virtue of the photochemical degradation method for the glucuronide linkage and on the basis of 1H- and 13C-nuclear magnetic resonance and secondary ion mass spectrum analyses, structures of acetyl-soyasaponins A1, A2, and A3 have been elucidated as 3-O-[β-D-glucopyranosyl-(1→2)-β-D-galactopyranosyl(1→2)-β-D-glucuronopyranosyl]-22-O-[2, 3, 4, 6-tetra-O-acetyl-β-D-glucopyranosyl(1→3)-α-L-arabinopyranosyl]soyasapogenol A (6a), 3-O-[β-D-galactopyranosyl-(1→2)-β-D-glucuronopyranosyl]-22-O-[2, 3, 4, 6-tetra-O-acetyl-β-D-glucopyranosyl(1→3)-α-L-arabinopyranosyl]soyasapogenol A (7a), and 3-O-[α-L-arabinopyranosyl(1→2)-β-D-glucuronopy-ranosyl]-22-O-[2, 3, 4, 6-tetra-O-acetyl-β-D-glucopyranosyl(1→3)-α-L-arabinopyranosyl]soya-sapogenol A (8a), respectively.

Probability of reversal in an election with more than two candidates

Consider an election with three candidates A1, A2 and A3. Suppose that N is the total number of votes cast of which A1 receives a1 votes, A2 receives a2 votes and A3 receives a3 = N - (a1 + a2) votes. We assume without loss of generality that a1 > a2 > a3. Suppose further that n votes are irregular or suspect. If these votes are removed it is possible that the result of the election may be reversed. Does such a possibility preclude the determination of the rightful winner without holding a new election?

Immunofluorescence studies on the expression of VH a allotypes by pre-B and B cells of homozygous and heterozygous rabbits.

Fluorochrome-conjugated antibodies specific for C mu determinants and VH a allotypes were used to examine pre-B cells and B lymphocytes for expression of these markers. The majority of mu+ bone marrow pre-B cells were shown to express a allotypic determinants in conjunction with C mu. Both pre-B and B cells from a2 a3 heterozygous rabbits showed allelic exclusion of these allotypes. Pre-B cells expressing the a2 or a3 specificities appeared to be generated in approximately equal numbers in heterozygotes, while B lymphocytes expressing a3 appeared to undergo preferential clonal expansion very early in development. It was also observed that rabbit bone marrow and blood contained a population of myeloid cells which, in a2 a3 heterozygotes, stained for both a2 and a3 determinants. The frequencies of this cell type, which exhibited bright immunofluorescence staining for a allotypes, could not be reduced by prolonged incubation at 37 degrees C but were readily reduced after cell suspensions were treated with low pH buffer. It is concluded that these myeloid cells bear high avidity Fc receptors for serum immunoglobulin and may be the culprits in studies which have found production of two a or b allotypes by individual B lymphocytes.

Parametric representation of the dilute polymer system to O(ϵ2): crossover from Wilson-Fisher to gaussian fixed point as the Flory temperature is approached

It is well known that the properties of scaling and universality exhibited by the polymer system have a very natural description in terms of the critical behaviour of an analogous magnetic system. This analogy is used to derive renormalisation-group equations directly for the polymer system. Solving these renormalisation-group equations a compact parametric description is obtained of the crossover from the Wilson-Fisher to gaussian fixed point displayed by the mean square size of a polymer (R2) and the second A2 and third A3 virial coefficients correct to O( epsilon 2) in d=4- epsilon spatial dimensions.