bluuebunny/crossref_metadata_2025 huggingface dataset:
Partition coefficients of quinones and hydroquinones and their relation to biochemical reactivity
Authors: Rich Peter R. , Harper Robert
Published: July 2002

Some major effects of ring substituents on the partition coefficients of quinone headgroups are described. Attention is drawn to the large differences in partition coefficients in cyclohexane/water of the two major freely diffusing redox forms, the quinone, Q, and the hydroquinone, QH2. Methoxy substituents cause a marked increase of the cyclohexane/water partition coefficient of the hydroquinone, but this effect is absent in the quinone and is also not seen in measurements in octanol/water. The relation between partition coefficients and biochemical specificity of quinone binding sites is explored.
c‐erb‐A mRNA content and triiodothyronine nuclear receptor binding capacity in rat liver according to vitamin A status
Authors: Pailler-Rodde I. , Garcin H. , Higueret P. , Begueret J.
Published: July 2002

Vitamin A is required for normal growth and development and synergistically acts with thyroid hormones in these processes. Effects of retinol dietary intake (0, 5, 50 U retinol/g food) on the triiodothyronine (T3) nuclear receptor were examined in rat liver. Properties of this receptor have been investigated by an in vitro binding method. The amount of c‐erb‐A mRNA has been deduced by reverse transcription and amplification methods (PCR). Results show that both retinol deficiency and excess leads to a reduced amount of c‐erb‐A mRNA and to a decreased T3 binding capacity, suggesting that retinol, or retinoic acid which is its natural metabolite, contributes to the regulation of the T3 nuclear receptor properties.
cDNA‐derived amino‐acid sequence of lentil seedlings' amine oxidase
Authors: Rossi Antonello , Petruzzelli Raffaele , Agrò Alessandro Finazzi
Published: July 2002

Lentil seedlings' amino oxidase (LSAO) cDNAs were identified in a cDNA λgi 10 library by plaques hybridization. The nucleotide sequence of a 2111 bp clone was determined. It contains part of a signal peptide, the complete sequence coding for the mature protein and the 3′‐untranslated region of the mRNA. The deduced protein sequence shows that the mature protein is composed of 569 amino acids with a molecular mass of 67 kda, also taking into account the glucidic component. The LSAOcDNA was identified by sequencing the N‐terminal part of the protein and several tryptic peptides. The protein sequence shows a characteristic hexapeptide present in amine oxidases containing 6‐hydroxydopa as the organic cofactor. Three conserved histidines might be the ligands of copper bound to the enzyme.
Induction of an electrogenic transfer of monovalent cations (K+, NH+4) in thylakoid membranes by N,N′‐dicyclohexylcarbodiimide
Authors: Opanasenko V.K. , Red'ko T.P. , Gubanova O.N. , Yaguzhinsky L.S.
Published: July 2002

The effect of N,N′‐dicyclohexylcarbodiimide (DCCD) on photosynthetic electron transport and light‐induced NH+
4 and K+ uptake in the presence of ammonium or nigericin was studied. DCCD alone had no effect on either the electron transport or the uptake of protons. The simultaneous action of DCCD and low concentrations of ammonium or nigericin was shown to lead to a significant increase in the electron transport rate and a decrease in the steady‐state uptake value of H+ and NH+
4 or K+. The effect of DCCD on these processes was compared with the effect of the ionophore, valinomycin, which transports potassium and ammonium cations through membranes. The conclusion was made that 1.0–1.5 mol DCCD per mol chlorophyll activated the transfer system of monovalent cations (K+ and NH+
4) in thylakoid membranes.
A slow anion channel in guard cells, activating at large hyperpolarization, may be principal for stomatal closing
Authors: Linder Birgit , Raschke Klaus
Published: July 2002

Slowly activating anion channel currents were discovered at micromolar ‘cytoplasmic’ Ca2+ during patch‐clamp measurements on guard‐cell protoplasts of Vicia faba and Xanthium strumarium. They activated at potentials as low as −200 Mv, with time constants between 5 and 60 s, and no inactivation. The broad voltage dependence exhibited a current maximum near −40 mV. The single‐channel open time was in the order of seconds, and the unitary conductance was 33 ps, similar to that of the already described ‘quick’ anion channel of guard cells. Because of its activity at low potentials, the slow anion channel may be essential for the depolarization of the plasmalemma that is required for salt efflux during stomatal closing.
Protein engineering of Drosophila alcohol dehydrogenase The hydroxyl group of Tyr152 is involved in the active site of the enzyme
Authors: Gonzålez-Duarte Ricard Albalat , Atrian Silvia
Published: July 2002

Drosophila alcohol dehydrogenase is the most studied member of the family of short‐chain alcohol dehydrogenases, although its tridimensional structure still remains unknown. We have engineered a Drosophila alcohol dehydrogenase in which tyrosine‐152, an invariant residue in all members of the family, has been substituted by phenylalanine. The mutated gene has been expressed in yeast and pure mutant enzyme has ban prepared by a one‐step FPLC chromatographic procedure, Drosophila alcohol dehydrogenase‐phenylalanine‐152 shows no enzymatic activity. This result suggests not only that tyrosine‐152 could constitute an essential building block of the active site but also that its hydroxyl group is directly involved in the redox reaction catalyzed by the enzyme.
Light‐induced structural changes in cytochrome c oxidase
Authors: Hallén Stefan , Oliveberg Mikael , Brzezinski Peter
Published: July 2002

We have investigated flash‐induced electrogenic events and absorbance changes in cytochrome c oxidase in the absence of dioxygen and carbon monoxide. Electrogenic events were studied using a Teflon‐bound layer of cytochrome c oxidase oriented in a phospholipid monolayer. Absorbance changes were observed exclusively in partly reduced cytochrome c oxidase; the largest changes were found in the one‐electron‐reduced species. Electrogenic events were detected in all reduction states of the enzyme. Both types of experiments displayed a rapid (< 0.5 μ;s) event followed by a biphasic relaxation. The time constants of the relaxation were 6 ± 2 μ;s and 70 ± 10 μ;s in the electrogenicity, and 9 ± 3 μ;s and 81 ± 6 μ;s in the absorbance changes (at ~22 °C). The kinetic absorbance difference spectrum was consistent with that of reduced minus oxidized haem. The experimental results are discussed in terms of structural changes in the vicinity of cytochrome a
3. These changes may play an important role in all studies that involve flash photolysis of cytochrome c oxidase‐ligand complexes.
Skin l‐tryptophan‐2,3‐dioxygenase and rat hair growth
Authors: Ishiguro Isao , Naito Junko , Saito Kuniaki , Nagamura Yoichi
Published: July 2002

We have identified a new enzyme, skin l‐tryptophan‐2,3‐dioxygenase (skin TDO), that catalyzes the degradation of l‐tryptophan into formylkynurenine in rats. The rate of this degradation peaks in all rats at 5 to 6 weeks after birth, and also, among rats depilated at 8 weeks old, at 10 to 11 weeks after birth. We have also observed that the properties of this enzyme are closer to those of hepatic l‐tryptophan‐2,3‐dioxygenase (hepatic TDO) than to indoleamine 2,3‐dioxygenase. Although an intraperitoneal injection of l‐tryptophan increased the activity of skin TDO to approximately 2.2 times greater than control values, an intraperitoneal injection of hydrocortisone and α‐methyl‐dl‐tryptophan, both compounds known to affect hepatic TDO activity, had no effect on skin TDO activity. The molecular weight of skin TDO was estimated to be 16.0 kDa, which is close to the molecular weight of hepatic TDO, yet a much larger molecule than indoleamine‐2,3‐dioxygenase. Increased hair growth rates paralleled increased levels of skin TDO activity in 5‐ to 6‐week‐old rats, and marked increases in the activity of skin TDO occurred 2 or 3 weeks after depilation. Enzyme activity was also greatest 2 days before the time of maximum hair root length. Therefore, skin TDO may play an important role in the initiation or suppression of rat hair growth.
Ion channels: molecular basis of ion selectivity
Authors: Imoto Keiji
Published: July 2002

Recent mutagenesis studies of the ion channel proteins have allowed us to identify amino acid residues critical in determining ion selectivity. Ion selectivity of a channel can be altered even by single animo acid substitutions. Functional analyses of mutants largely support views in classical biophysics that the pore size and the fixed charges are major determinants of ion selectivity. For full understanding of the molecular mechanism of ion selectivity, elucidation of the tertiary structure of channel proteins remains essential.
Phosphoinositides in membranes that build up the triads of rabbit skeletal muscle
Authors: Milting Hendrik , Heilmeyer Ludwig M.G. , Thieleczek Rolf
Published: July 2002

The total membrane concentrations of PtdIns, PtdIns4P, and PtdIns(4,5)P2 contribute to the functional capacity of the Ins(1,4,5)P3 signalling system which is operating in skeletal muscle but the function of which is still unknown. Total amounts of these phosphoinositides have been determined in purified membranes of transverse tubules (TT) and terminal cisternae (TC) of the sarcoplasmic reticulum (SR) of rabbit skeletal muscle. PtdIns and PtdIns4P have been detected in both membrane systems whereas PtdIns(4,5)P2 (290 μmol/mol phospholipid) is confined only to TT. A much greater pool of PtdIns(4,5)P2 seems, however, to be located in the sarcolemma away from the triadic junction.
YY1 is involved in the regulation of the bi‐directional promoter of the Surf‐1 and Surf‐2 genes
Authors: Gaston Kevin , Fried Mike
Published: July 2002

The Surfeit locus is an unusual cluster of at least 6 housekeeping genes whose organisation is conserved between birds and mammals. We have previously shown that the divergently transcribed Surf‐1 and Surf‐2 genes are separated by a bi‐directional, TATA‐Iess promoter. In mouse, the Surf‐1/Surf‐2 promoter contains three important factor binding sites: Su1, Su2, and Su3. These sites are conserved between the mouse and human Surf‐1/Surf‐2 promoters, bind nuclear factors in vitro, and are required for accurate and efficient expression of Surf‐1 and Surf‐2 in vivo. Using gel retardation assays, methylation interference experiments, and specific antibodies we demonstrate that the Su1 binding factor is the initiator protein YY1. Over‐expression of YY1 results in a major stimulation of transcription in the Surf‐1 direction and a minor stimulation of transcription in the Surf‐2 direction.
Ca2+‐ATPase distributes differently in cardiac sarcolemma than dihydropyridine receptor α1 subunit and Na+/Ca2+ exchanger
Authors: Iwata Yuko , Hanada Hironori , Takahashi Masami , Shigekawa Munekazu
Published: July 2002

We have investigated the distribution of the sarcolemmal Ca2+ transporters in hamster and dog ventricular myocytes by immunocytochemical and membrane fractionation techniques. The data suggest that the DHP receptor α1 subunit and the Na+/Ca2+ exchanger are present in surface sarcolemma as well as T‐tubule membranes located at the cardiac dyads. Compared with these Ca2+ transporters, the sarcolemmal Ca2+‐ATPase is much less abundant in the latter fraction. Thus the sarcolemmal Ca2+‐ATPase seems to be located predominantly in surface sarcolemma.
Genetic disorders of the red cell membranes
Authors: Delaunay Jean
Published: July 2002

The red cell membrane is comprised of a lipid bilayer studded with transmembrane proteins, and laminated by a protein network, the membrane skeleton, at the surface of the inner monolayer. The erythrocyte owes its mechanical properties to the membrane skeleton. Hereditary spherocytosis, hereditary elliptocytosis or poikilocytosis, Southeast Asian ovalocytosis are hereditary hemolytic anemias, due to mutations in the genes encoding ankyrin, the anion exchanger, spectrin, protein 4.1 or protein 4.2, which are main proteins of the membrane. Recent advances in the field have led to fundamental questions.
ATF/CREB site mediated transcriptional activation and p53 dependent repression of the cyclin A promoter
Authors: Desdouets Chantal , Ory Catherine , Matesic Graziella , Soussi Thierry , Bréchot Christian , Sobczak-Thépot Joëlle
Published: July 2002

Cyclin A is a pivotal regulatory protein which, in mammalian cells, is involved in the S phase of the cell cycle. Transcription of the human cyclin A gene is cell cycle regulated through tight control of its promoter. We have previously shown that the ATF/CREB site, present in the cyclin A promoter, mediates transcriptional regulation by CAMP responsive element binding proteins. The main goal of the present study was to investigate whether this site is involved in transcriptional regulation of the gene. We have constructed stable NIH‐3T3 cell lines that express the luciferase reporter gene under the control of normal or mutated versions of the cyclin A promoter. We show that the ATF/CREB is required to achieve maximal levels of transcription from the cyclin A promoter starting in late G1. We also show that down‐regulation of the cyclin A promoter by p53 does not implicate a direct binding of p53 to its cognate consensus sequence but occurs probably by interference with trans‐activating factors. This result suggests that p53 can interfere with transcription of the cyclin A gene, in the absence of a TATA sequence in the promoter.
Redox‐linked conformational changes in cytochrome c oxidase
Authors: Wittung Pernilla , Malmström Bo G.
Published: July 2002

The CD spectrum of oxidized cytochrome oxidase in the wavelength region 185–260 nm shows that the secondary structure of the protein consists of close to 60% α‐helix and slightly less than 20% β‐structure. CD spectra of oxidized cytochrome oxidase, of half and fully reduced carboxycytochrome oxidase as well as of fully reduced cytochrome oxidase, have been recorded in the wavelength region 200–260 nm. The results demonstrate a conformational change on going from the oxidized to the half reduced state in carboxycytochrome oxidase; no further change occurs on full reduction. A conformational change is also seen in the fully reduced enzyme without bound CO. The conformational transitions are suggested to be part of the proton pumping mechanism of cytochrome oxidase.
Isolation and pharmacological characterisation of δ‐atracotoxin‐Hv1b, a vertebrate‐selective sodium channel toxin
Authors: Szeto Tim H. , Birinyi-Strachan Liesl C. , Smith Ross , Connor Mark , Christie Macdonald J. , King Glenn F. , Nicholson Graham M.
Published: July 2002

δ‐Atracotoxins (δ‐ACTXs) are peptide toxins isolated from the venom of Australian funnel‐web spiders that slow sodium current inactivation in a similar manner to scorpion α‐toxins. We have isolated and determined the amino acid sequence of a novel δ‐ACTX, designated δ‐ACTX‐Hv1b, from the venom of the funnel‐web spider Hadronyche versuta. This 42 residue toxin shows 67% sequence identity with δ‐ACTX‐Hv1a previously isolated from the same spider. Under whole‐cell voltage‐clamp conditions, the toxin had no effect on tetrodotoxin (TTX)‐resistant sodium currents in rat dorsal root ganglion neurones but exerted a concentration‐dependent reduction in peak TTX‐sensitive sodium current amplitude accompanied by a slowing of sodium current inactivation similar to other δ‐ACTXs. However, δ‐ACTX‐Hv1b is approximately 15–30‐fold less potent than other δ‐ACTXs and is remarkable for its complete lack of insecticidal activity. Thus, the sequence differences between δ‐ACTX‐Hv1a and ‐Hv1b provide key insights into the residues that are critical for targeting of these toxins to vertebrate and invertebrate sodium channels.
Distinct isoforms of ADPglucose pyrophosphatase and ADPglucose pyrophosphorylase occur in the suspension‐cultured cells of sycamore (Acer pseudoplatanus L.)
Authors: Baroja-Fernández Edurne , Zandueta-Criado Aitor , Rodrı́guez-López Milagros , Akazawa Takashi , Pozueta-Romero Javier
Published: July 2002

The intracellular localizations of ADPglucose pyrophosphatase (AGPPase) and ADPglucose pyrophosphorylase (AGPase) have been studied using protoplasts prepared from suspension‐cultured cells of sycamore (Acer pseudoplatanus L.). Subcellular fractionation studies revealed that all the AGPPase present in the protoplasts is associated with amyloplasts, whereas more than 60% of AGPase is in the extraplastidial compartment. Immunoblots of amyloplast‐ and extraplastid‐enriched extracts further confirmed that AGPase is located mainly outside the amyloplast. Experiments carried out to identify possible different isoforms of AGPPase in the amyloplast revealed the presence of soluble and starch granule‐bound isoforms. We thus propose that ADPglucose levels linked to starch biosynthesis in sycamore cells are controlled by enzymatic reactions catalyzing the synthesis and breakdown of ADPglucose, which take place both inside and outside the amyloplast.
RNA: protein interactions associated with satellites of panicum mosaic virus
Authors: Desvoyes Bénédicte , Scholthof Karen-Beth G
Published: July 2002

The interactions between satellite panicum mosaic virus (SPMV) capsid protein (CP) and its 824 nucleotide (nt) single stranded RNA were investigated by gel mobility shift assay and Northwestern blot assay. SPMV CP has specificity for its RNA at high affinity, but little affinity for non‐viral RNA. The SPMV CP also bound a 350 nt satellite RNA (satRNA) that, like SPMV, is dependent on panicum mosaic virus for its replication. SPMV CP has the novel property of encapsidating SPMV RNA and satRNA. Competition gel mobility shift assays performed with a non‐viral RNA and unlabeled SPMV RNA and satRNA revealed that these RNA:protein interactions were in part sequence specific.
Two novel calcium‐binding proteins from cytoplasmic granules of the protozoan parasite Entamoeba histolytica
Authors: Nickel Rosa , Jacobs Thomas , Urban Britta , Scholze Henning , Bruhn Heike , Leippe Matthias
Published: July 2002

We report on the molecular characterisation of two novel granule proteins of the protozoon and human pathogen Entamoeba histolytica. The proteins, which were named grainin 1 and 2, show a considerable structural similarity to calcium‐binding proteins, particularly within EF‐hand motifs. Each grainin possesses three of these putative calcium‐binding sites. Based on careful inspection of known structures of protein families containing EF‐hands, a domain of grainin 1 covering two EF‐hand motifs was modeled by homology. Calcium‐binding activity of grainins was demonstrated by two independent methods. These granule proteins may be implicated in functions vital for the primitive phagocyte and destructive parasite such as control of endocytotic pathways and granule discharge.
Multiple Holliday junction resolving enzyme activities in the Crenarchaeota and Euryarchaeota
Authors: Kvaratskhelia Mamuka , Wardleworth Benjamin N , White Malcolm F
Published: July 2002

Holliday junction resolving enzymes are required by all life forms that catalyse homologous recombination, including all cellular organisms and many bacterial and eukaryotic viruses. Here we report the identification of three distinct Holliday junction resolving enzyme activities present in two highly divergent archaeal species. Both Sulfolobus and Pyrococcus share the Hjc activity, and in addition possess unique secondary activities (Hje and Hjr). We propose by analogy with the two other domains of life that the latter enzymes are viral in origin, suggesting the widespread existence of archaeal viruses that rely on homologous recombination as part of their life cycle.
The plant homologue of the defender against apoptotic death gene is down‐regulated during senescence of flower petals1
Authors: Orzáez Diego , Granell Antonio
Published: July 2002

© 1997 Federation of European Biochemical Societies.
Characterization and receptor specific toxicity of two diphtheria toxin‐related interleukin‐3 fusion proteins DAB389–mIL‐3 and DAB389–(Gly4Ser)2‐mIL‐3
Authors: Liger Dominique , vanderSpek Johanna C , Gaillard Carole , Cansier Christophe , Murphy John R , Leboulch Philippe , Gillet Daniel
Published: July 2002

We have constructed two fusion proteins, DAB389–mIL‐3 and DAB389‐(Gly4Ser)2–mIL‐3, in which the receptor‐binding domain of diphtheria toxin is replaced by mouse interleukin‐3 (IL‐3). Cytotoxic activity of the fusion toxins was observed on three out of six cell lines assayed. This toxicity was mediated through binding to the IL‐3 receptor as it was inhibited in a dose‐dependent manner with murine IL‐3 or anti‐IL‐3 neutralizing antibodies. DAB389–(Gly4Ser)2‐mIL‐3 was up to 5 times more toxic than DAB389–mIL‐3, depending on the cell line (0.8×10−10M<IC50<3×10−10M). These proteins can be used for the detection of IL‐3 receptors on mouse cells and should allow for the selective elimination of IL‐3 receptor‐positive pluripotent hematopoietic stem cells prior to bone marrow transplantation.
Protein processing:
Authors: Brooks Doug A
Published: July 2002

Genetic diseases associated with an enzyme deficiency frequently have reduced intracellular levels of the mutant protein, despite apparently normal levels of message and protein synthesis. It has been suggested that the endoplasmic reticulum (ER) can recognise mutant protein as incorrectly folded and invoke ‘quality control’ processes which cause the retention and degradation of this protein. This process may occur, even for mutations which do not abrogate protein activity, contributing directly to pathophysiology. Genetic diseases associated with defects in ER and Golgi processing proteins have also been reported and generally result in impaired processing of multiple protein products. In this review the role of the ER and Golgi in the pathogenesis of genetic diseases relating to the vacuolar network are discussed.
Analysis of cytokine profile in human colonic mucosal FcϵRI‐positive cells by single cell PCR: inhibition of IL‐3 expression in steroid‐treated IBD patients
Authors: Ligumsky Moshe , Kuperstein Valentina , Nechushtan Hovav , Zhang Zhaocheng , Razin Ehud
Published: July 2002

Mast cells can serve as a possible important source of cytokine production in inflamed tissue which can be regulated by stimuli different from those activating other immune system cells. To study the expression of specific genes in mast cells derived from small human colonic mucosal endoscopic biopsies, we first modified a previously reported procedure to achieve a significantly enriched mast cell fraction. Then, by using single‐cell RT‐PCR analysis the expression of the IgE Fc receptor (FcϵRI) and c‐kit mRNA was determined. It was observed that the FcϵRI‐positive cells also expressed c‐kit. This observation provided further evidence that FcϵRI‐positive cells are indeed mast cells. Analysis of biopsies from 12 patients (four control and eight patients with inflammatory bowel disease (IBD)) was carried out, revealing that all of the FcϵRI‐positive cells expressed IL‐3, while the expression of IL‐4 was detected only in some of these positive cells. TNFα was not detected in these cells. Therefore, it would seem that most intestinal mast cells produce IL‐3. Since it has been reported that IL‐3 synthesis was down‐regulated in steroid‐treated cells, the expression pattern of IL‐3 in intestinal mast cells derived from steroid‐treated IBD patients was then determined. IL‐3 mRNA was detected in only two out of 24 FcϵRI‐positive cells derived from these steroid‐treated patients. These results lend strong support to the idea that the down‐regulation of IL‐3 in mast cells derived from steroid‐treated IBD patients occurs in vivo and could be an important mechanism for immunomodulation in IBD.
Cloning, purification, crystallization, and preliminary X‐ray diffraction analysis of cystathionine γ‐synthase from E. coli
Authors: Wahl Markus C , Huber Robert , Prade Lars , Marinkovic Snezan , Messerschmidt Albrecht , Clausen Tim
Published: July 2002

The Escherichia coli metB gene has been PCR‐extracted from genomic DNA and placed under the control of a tac and a T7 promoter in plasmids pCYB1 and pET22b(+), respectively, to produce overexpressing bacterial strains for the gene product, cystathionine γ‐synthase. Efficient purification procedures have been developed for a C‐terminally intein‐tagged version and the wild‐type target protein, yielding the product in a quantity and homogeneity amenable to high‐resolution single‐crystal X‐ray analysis. Crystals have been obtained in space group P1 with unit cell constants a=82.2 Å, b=84.2 Å, c=116.2 Å, α=107.0°, β=96.3°, γ=108.0°, suggesting eight monomers per asymmetric unit (VM=2.23 Å3/Da). Crystals diffract to beyond 2.6 Å resolution and a data set complete to 2.8 Å resolution has been collected using a rotating anode X‐ray source. A cryogenic buffer system has been developed to allow synchrotron data collection. Patterson self rotation searches reveal the presence of two independent tetramers with local 222 symmetry in an asymmetric unit. The crystallographic results corroborate and extend previous solution studies regarding the quaternary organization of the enzyme.
Eicosanoids mediate induction of immune genes in the fat body of the silkworm, Bombyx mori
Authors: Morishima Isao , Yamano Yoshiaki , Inoue Kenji , Matsuo Noriyuki
Published: July 2002

The expression of cecropin and lysozyme genes is induced in response to bacterial peptidoglycan in the fat body of the silkworm, Bombyx mori. Specific inhibitors of either phospholipase A2, cyclooxygenase or lipoxygenase significantly inhibit the induction of the immune genes both in vivo and in cultured fat body as detected by means of Northern hybridization. Arachidonic acid injected into the larvae induces the expression of the cecropin and lysozyme genes. The findings support the idea that eicosanoids mediate some process leading to the expression of immune genes in the fat body following recognition of peptidoglycan as a signal for invading bacteria.
HPLC determination of photosynthetic pigments during greening of etiolated barley leaves
Authors: Nakamura Akimasa , Watanabe Tadashi
Published: July 2002

The temporal evolution of pigment composition during greening of etiolated barley leaves was investigated by reversed‐phase HPLC with particular attention to chlorophyll (Chl) a′ (C132 epimer of Chl a), which had been detected by ourselves in photosystem (PS) I particles. At early stages of greening, the Chl a′/Chl a molar ratio rapidly increased to a level more than twice that in mature leaves, then gradually leveled off, accompanied by a growth of the Chl b/Chl a ratio, to the mature level. After 3 h of illumination, the temporal evolution of the Chl a′/Chl a molar ratio nearly paralleled that of the P700/Chl a ratio with a stoichiometry Chl a′/P700≅2: this strongly suggests that Chl a′ is biosynthesized as a constituent of the PS I reaction center complex.
The promoter of human p22/PACAP response gene 1 (PRG1) contains functional binding sites for the p53 tumor suppressor and for NFκB
Authors: Schäfer Heiner , Diebel Julia , Arlt Alexander , Trauzold Anna , Schmidt Wolfgang E.
Published: July 2002

We describe functional binding sites for the tumor suppressor p53 and for NFκB residing in the promoter of the novel human early response gene p22/PRG1 (IEX‐1/DIF‐2). Gel shift and supershift assays demonstrate binding of p53 and NFκB to their corresponding sites in vitro. CAT‐reporter gene assays show transactivation of the human p22/PRG1 promoter by p53 in Hep3B cells stably transfected with a temperature‐sensitive mutant p53, but not in p53‐deficient Hep3B cells. TNFα induced NFκB dependent transactivation was shown in HepG2 cells or in 818‐4 pancreatic cancer cells. These data imply that human p22/PRG1 is a target gene for p53 and NFκB involved in growth regulation and stress response.
Characterisation of a novel Drosophila melanogaster testis specific PP1 inhibitor related to mammalian inhibitor‐2: identification of the site of interaction with PP1
Authors: Helps Nicholas R. , Vergidou Cornillia , Gaskell Terri , Cohen Patricia T.W.
Published: July 2002

A novel Drosophila melanogaster protein, termed inhibitor‐t, that bears 41% sequence similarity to human protein phosphatase inhibitor‐2 has been identified using human protein phosphatase 1 (PP1) in the yeast two hybrid system. Inhibitor‐t mRNA is detected in adult males, larvae and pupae and the 184 amino acid thermostable protein located only in testis. The gene for inhibitor‐t maps to cytological location 86F1 on the third chromosome. Bacterially expressed inhibitor‐t specifically inhibits both mammalian and D. melanogaster PP1 catalytic subunits with an IC50 of approximately 200 nM. A motif ‐FEX1X2RK‐, conserved between inhibitor‐t, inhibitor‐2 and its Saccharomyces cerevisiae homologue Glc8, is demonstrated to be required for binding to PP1.
Characterization of the cullin and F‐box protein partner Skp1
Authors: Ng Raymond W.M. , Arooz Talha , Yam Cain H. , Chan Iris W.Y. , Lau Anita W.S. , Poon Randy Y.C.
Published: July 2002

Skp1 interacts with cullins, F‐box containing proteins, and forms a complex with cyclin A‐Cdk2 in mammalian cells. Skp1 is also involved in diverse biological processes like degradation of key cell cycle regulators, glucose sensing, and kinetochore function. However, little is known about the structure and exact function of Skp1. Here we characterized the interaction between Skp1 and the F‐box protein Skp2. We show that Skp1 can bind to Skp2 in vitro using recombinant proteins, and in vivo using the yeast two‐hybrid system. Deletion analysis of Skp1 indicated that most of the Skp1 protein is required for binding to Skp2. In mammalian cell extracts, a large portion of Skp1 appears to associate with proteins other than Skp2. Biochemical analysis indicated that Skp1 is likely to be a flexible, non‐spherical protein, and is capable of forming dimers.
cAMP‐dependent protein kinase and phosphoproteins in mammalian mitochondria. An extension of the cAMP‐mediated intracellular signal transduction
Authors: Papa Sergio , Sardanelli Anna Maria , Scacco Salvatore , Technikova-Dobrova Zuzana
Published: July 2002

Evidence has been obtained for the occurrence of a cAMP‐dependent serine protein kinase associated with the inner membrane/matrix of mammalian mitochondria. The catalytic site of this kinase is localized at the inner side of the inner membrane, where it phosphorylates a number of mitochondrial proteins. One of these has been identified as the AQDQ subunit of complex I. cAMP‐dependent phosphorylation of this protein promotes the activity of complex I and mitochondrial respiration. A 5 bp duplication in the nuclear gene encoding this protein has been found in a human patient, which eliminates the phosphorylation site. PKA anchoring proteins have recently been identified in the outer membrane of mammalian mitochondria, which could direct phosphorylation of proteins at contact sites with other cell structures.
Cysteine 29 is the major palmitoylation site on stomatin
Authors: Snyers Luc , Umlauf Ellen , Prohaska Rainer
Published: July 2002

The 31 kDa membrane protein stomatin was metabolically labeled with tritiated palmitic acid in the human amniotic cell line UAC and immunoprecipitated. We show that the incorporated palmitate is sensitive to hydroxylamine, indicating the binding to cysteine residues. Stomatin contains three cysteines. By expressing a myc‐tagged stomatin and substituting the three cysteines by serine, individually or in combination, we demonstrate that Cys‐29 is the predominant site of palmitoylation and that Cys‐86 accounts for the remaining palmitate labeling. Disruption of Cys‐52 alone does not show any detectable reduction of palmitic acid incorporation. Given the organization of stomatin into homo‐oligomers, the presence of multiple palmitate chains is likely to increase greatly the affinity of these oligomers for the membrane and perhaps particular lipid domains within it.
The zebrafish genome contains two distinct selenocysteine tRNA[Ser]Sec genes
Authors: Xu Xue-Ming , Zhou Xuan , Carlson Bradley A. , Kyun Kim Lark , Huh Tae-Lin , Jae Lee Byeong , Hatfield Dolph L.
Published: July 2002

The zebrafish is widely used as a model system for studying mammalian developmental genetics and more recently, as a model system for carcinogenesis. Since there is mounting evidence that selenium can prevent cancer in mammals, including humans, we characterized the selenocysteine tRNA[Ser]Sec gene and its product in zebrafish. Two genes for this tRNA were isolated and sequenced and were found to map at different loci within the zebrafish genome. The encoding sequences of both are identical and their flanking sequences are highly homologous for several hundred bases in both directions. The two genes likely arose from gene duplication which is a common phenomenon among many genes in this species. In addition, zebrafish tRNA[Ser]Sec was isolated from the total tRNA population and shown to decode UGA in a ribosomal binding assay.
Hydrolysis of NADP+ by platelet CD38 in the absence of synthesis and degradation of cyclic ADP‐ribose 2′‐phosphate
Authors: Torti Mauro , Bertoni Alessandra , Canobbio Ilaria , Sinigaglia Fabiola , Balduini Cesare
Published: July 2002

CD38 is a multifunctional cell surface ectoenzyme that catalyzes both the synthesis of cyclic ADP‐ribose from NAD+ and its hydrolysis to ADP‐ribose. In this work, we investigated the metabolism of NADP+ by CD38 expressed on human platelets. Incubation of either platelet membranes or intact cells with NADP+ resulted in the rapid and time‐dependent accumulation of ADP‐ribose 2′‐phosphate that paralleled the consumption of the substrate. However, under the same conditions, synthesis of cyclic ADP‐ribose 2′‐phosphate was not observed. By immunoprecipitation experiments, we identified CD38 as the enzyme responsible for the observed NADP+ glycohydrolase activity. The lack of detection of cyclic ADP‐ribose 2′‐phosphate was not due to its rapid hydrolysis, since direct incubation of platelet membranes with cyclic ADP‐ribose 2′‐phosphate did not result in the formation of ADP‐ribose 2′‐phosphate. By contrast, the same membrane samples expressed a significant ability to hydrolyze cyclic ADP‐ribose to ADP‐ribose. The absence of cyclic ADP‐ribose 2′‐phosphate hydrolase activity was also confirmed using high concentrations of substrate and by analysing both intact Jurkat T‐lymphocytes and immunoprecipitated CD38. These results indicate that CD38, which is a multifunctional enzyme towards NAD+, displays exclusively a NADP+ glycohydrolase activity and is unable to catalyze both the synthesis and the hydrolysis of cyclic ADP‐ribose 2′‐phosphate.
Indomethacin‐induced G1/S phase arrest of the plant cell cycle
Authors: Ehsan Hashimul , Roef Luc , Witters Erwin , Reichheld Jean-Philippe , Van Bockstaele Dirk , Inzé Dirk , Van Onckelen Harry
Published: July 2002

In animal systems, indomethacin inhibits cAMP production via a prostaglandin‐adenylyl cyclase pathway. To examine the possibility that a similar mechanism occurs in plants, the effect of indomethacin on the cell cycle of a tobacco bright yellow 2 (TBY‐2) cell suspension was studied. Application of indomethacin during mitosis did not interfere with the M/G1 progression in synchronized BY‐2 cells but it inhibited cAMP production at the beginning of the G1 phase and arrested the cell cycle progression at G1/S. These observations are discussed in relation to the putative involvement of cAMP biosynthesis in the cell cycle progression in TBY‐2 cells.
Drosophila melanogaster protein phosphatase inhibitor‐2: identification of a site important for PP1 inhibition
Authors: Helps Nicholas R. , Cohen Patricia T.W.
Published: July 2002

A database search with human protein phosphatase inhibitor‐2 (I‐2) identified a Drosophila melanogaster cDNA that encoded a protein identical in length and sharing 39% amino acid identity (58% similarity) with human I‐2. The mRNA encoding this protein is expressed in both sexes and throughout development, unlike Drosophila inhibitor‐t. The bacterially expressed protein was a specific inhibitor of protein phosphatase 1 with an IC50 of <1 nM, confirming that it is the Drosophila homologue of mammalian inhibitor‐2. Mutation of Phe residues conserved in I‐2 from lower and higher eukaryotes showed that Phe‐33 is important for inhibition of PP1c.
Abortion and contraceptive practices in Eastern Europe
Authors: Kovács L.
Published: July 2002

In countries of the CCEE region (Countries of Central and Eastern Europe) the very high incidence of pregnancy termination is characteristic of family planning and the notion ‘contraception instead of abortion’ has not yet been achieved. The causes and consequences of this unfortunate situation will be reviewed: the reproductive health indicators in the area; the status of contraceptive use and of abortion; the impact of legislation in the different countries; and the efforts to achieve changes. The conclusions of the ‘Szeged Declaration’ which led to an increase in contraceptive prevalence will be discussed.
A new model for collaboration: the alliance for microbicide development
Authors: Harrison P.F.
Published: July 2002

Vaginal microbicides for preventing sexually‐transmitted infection and/or conception are a novel, much needed technology, yet not seen by industry as having attractive market potential. Nor is the public sector acting with the urgency, priority, and investment that would compensate for lack of private financing, shape the necessary basic and applied research agendas, and spur the dedicated development crucial to advancing this field. The Alliance for Microbicide Development was constituted through a Rockefeller Foundation grant to advocate for and educate about microbicide development, track and communicate product development and regulatory status, contribute to enhanced efficiency in preclinical and clinical processes and, later, help establish a base for matching funds to support combination and comparative studies. After 1 year of existence, the Alliance has proved its value as an innovative collaborative model, having generated and catalyzed a large volume of activity towards its objectives in all priority areas identified by its members.
Matrix and cell injury due to sub‐impact loading of adult bovine articular cartilage explants: effects of strain rate and peak stress
Authors: Quinn T. M. , Allen R. G. , Schalet B. J. , Perumbuli P. , Hunziker E. B.
Published: July 2002

Mechanical overloading of cartilage has been implicated in the initiation and progression of osteoarthrosis. Our objectives were to identify threshold levels of strain rate and peak stress at which sub‐impact loads could induce cartilage matrix damage and chondrocyte injury in bovine osteochondral explants and to explore relationships between matrix damage, spatial patterns of cell injury, and applied loads. Single sub‐impact loads characterized by a constant strain rate between 3 × 10−5 and 0.7 s−1 to a peak stress between 3.5 and 14 MPa were applied, after which explants were maintained in culture for four days. At the higher strain rates, matrix mechanical failure (tissue cracks) and cell deactivation were most severe near the cartilage superficial zone and were associated with sustained increased release of proteoglycan from explants. In contrast, low strain rate loading was associated with cell deactivation in the absence of visible matrix damage. Furthermore, cell activity and proteoglycan synthesis were suppressed throughout the cartilage depth, but in a radially dependent manner with the most severe effects at the center of cylindrical explants. Results highlight spatial patterns of matrix damage and cell injury which depend upon the nature of injurious loading applied. These patterns of injury may also differ in terms of their long‐term implications for progression of degradative disease and possibilities for cartilage repair. © 2001 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Home Based Life Saving Skills: Promoting Safe Motherhood Through Innovative Community‐Based Interventions
Authors: Sibley Lynn , Buffington Sandra Tebben , Beck Diana , Armbruster Deborah
Published: July 2002

In much of the developing world, home birth with unskilled attendants is the norm, and maternal and neonatal mortality rates are high. A comprehensive approach to address this problem needs to upgrade referral facilities and strengthen the skills of trained health care providers. To improve pregnancy outcomes, a program must also provide education, motivation, and mobilization of pregnant women, families, and communities (whose members must come to a common understanding of the need for and the means to prevent death of a woman or neonate). Consequently, the American College of Nurse Mid‐wives (ACNM) has expanded the Life Savings Skills Series to include Home Based Life Saving Skills (HBLSS). HBLSS is a community and competency‐based program that aims to reduce maternal and neonatal mortality by increasing access to basic life saving measures within the home and community and by decreasing delays in reaching referral facilities where life‐threatening problems can be managed.
Modeling and Control of Networked Discrete‐Event Systems
Authors: Lin Feng
Published: May 2020

Modern engineering systems and cyber‐physical systems often consist of many distributed and networked physical plants, control units, and other devices with wired or wireless communication networks to exchange information between controllers and plants. These systems are called networked systems. In this article, we review supervisory control of networked discrete‐event systems. We first discuss how to model networked discrete‐event systems and how to obtain state estimates using a networked observer. We then introduce and solve the following supervisory control problems of networked discrete‐event systems: (i) (nondeterministic) supervisory control problem, (ii) deterministic supervisory control problem, (iii) nonblocking supervisory control problem, (iv) robust supervisory control problem, (v) robust deterministic supervisory control problem, (vi) deterministic decentralized supervisory control problem, and (vii) nonblocking decentralized supervisory control problem. We present and prove necessary and sufficient conditions for solving the above problems. Finally, we list the open problems in supervisory control of networked discrete‐event systems.
Advances in Transmitarray Antennas
Authors: Feng Peng‐Yu , Qu Shi‐Wei , Xiao Lin
Published: May 2020

Recent advances in the art of transmitarray antenna (TAA) designs are summarized in this article, mainly focusing on the TAA element designs, improved feeding mechanisms, methods of designing wideband and ultra‐wideband TAAs, and TAAs for beam‐steering applications. Firstly, according to the diverse‐phase shifting mechanisms, representative TAA elements in the available literatures are categorized into four groups, including the receiving–transmitting elements, multilayer frequency‐selective surface‐type elements, polarization‐conversion elements, and phase‐rotation elements. Based on their own specific properties, designers can flexibly select the proper elements for different application scenarios. Moreover, primarily aiming at reducing the overall profile, some improved feeding mechanisms are discussed, for example, the folded TAA, TAA with the feeds of the multihorn configuration, the auxiliary small TAA, the integrated leaky‐wave antenna, the Cassegrain reflectarray, or a small‐scale array antenna. Subsequently, numerous typical solutions to improve the inherently narrow bandwidths of the TAAs are also presented. It can be concluded that the wideband performances of the non‐true‐time‐delay TAA are realized by optimizing the element‐phase errors and transmission losses at all designing frequencies. If the true‐time‐delay elements are employed, the key point is utilizing their group delays to appropriately compensate the spatial phase delays. Finally, for highly demanded beam‐steering applications, the TAAs incorporated with the techniques of reconfigurable, mechanical scan, switched beam, or phased array antenna (PAA) feed are introduced. Specifically, representative designs of the PAA‐fed TAAs are presented in detail, which will be a promising technical candidate of high‐gain beam scanning antennas.
Floquet Modal Analysis of Infinite and Finite Waveguide Phased Array Antennas
Authors: Bhattacharyya Arun K.
Published: May 2020

Analysis of a finite array using Floquet modal expansion is presented. The analysis essentially employs the characteristics of an infinite array to estimate the performance of a finite array including mutual coupling effects. The infinite array characteristics are obtained using Floquet modal expansion of the fields. It is shown that the coupling coefficients between the array elements can be determined from the active reflection coefficients of an element in an infinite array environment. The scattering matrix formulation is then invoked to obtain the reflection coefficients for the elements of a finite array. It is then shown that the vector form of the active element pattern, which includes the mutual coupling effects, can be determined from the Floquet modal transmission coefficients. The radiation pattern of a finite array with an arbitrary excitation can be computed therefrom. Numerical results for the reflection coefficients and active element patterns of an open‐ended waveguide array are shown. It is found that under certain conditions, the active element pattern is independent of frequency and cell size, while the gain increases with frequency. The explanation of such a behavior is presented.
Optically Driven, RF Transmit Phased Array Antennas for Mobile Communications and Wireless Networks
Authors: Prather Dennis W. , Shi Shouyuan , Konkol Matthew R. , Schneider Garrett J. , Murakowski Janusz , Peng Yao , Schuetz Christopher A.
Published: May 2020

This article introduces the use of optically fed, RF transmitting antennas for mobile communications and wireless networks. Motivation for the development of such antennas arises from the rapidly expanding allocations of electromagnetic spectrum by the Federal Communications Commission (FCC), which introduced spectral allocations extending up to 240 GHz. Because all electrical devices become lossy at such frequencies, photonic devices offer an attractive alternative. This article presents an overview of the use of photonic devices and systems for feeding and controlling RF phased array antennas for wireless communications. In particular, it introduces the concept of a current sheet as the ideal phase array antenna that offers a frequency‐independent impedance. The challenge has been the difficulty in designing a feed network capable of realizing such a dense array of current elements. To the extent that a photodetector is very small in comparison to RF wavelengths, it can serve as an ideal current source for a dense array. In addition, this article introduces not only broadband feed networks using photodetectors, but it also introduces novel feed architectures that offer significant control of the beam‐forming and data‐encoding to realize truly viable communication antennas.
Quality Monitoring and Control in Additive Manufacturing
Authors: Colosimo Bianca M.
Published: May 2020

Additive manufacturing has a great potential for the development of innovative industrial applications in different domains, as it enables the production of complex shapes, topologically optimized structures, and high‐value‐added components with novel embedded functionalities that are difficult or even impossible to produce with traditional technologies. However, stringent quality standards and qualification requirements impose defect‐free and first‐time‐right capabilities that are still challenging to achieve with state‐of‐the‐art AM systems. This article discusses existing solutions and open challenges for quality modeling, monitoring, and control in AM.