bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of photocontrol of aspartate kinase in barley (Hordeum vulgare L.) seedlings
Authors: Rao S. S. , Kochhar S. , Kochhar V. K. 
Published: July 2007

AbstractAspartate kinase (AK) activity is regulated by light. The activity was more in light exposed barley seedlings than those grown in the dark. The light effect was manifested even with small exposures of 5 min duration and red light was more effective than white light in this respect. The effect of 5 min red light could be reversed by a 5 min pulse of far‐red light indicating the involvement of phytochrome in this response. The phytochrome is also involved in long term light effects (24 hr exposures with white light). Ca++ takes part in the signal transduction pathway for this light response. Western blot analysis using antibodies raised against the purified lysine‐ and threonine‐sensitive AK isoenzymes from spinach leaves showed no cross reaction with the antibodies to the threonine‐sensitive AK in the dark and 5 min far‐red light exposed seedlings. But the protein band was detected in the white and red lights. Northern blot analysis of seedlings grown under dark and exposed to white, red and far‐red lights and probed with the gene encoding aspartokinase‐homoserine dehydrogenase (AKHSD) protein indicated that the gene was differentially expressed. In dark grown seedlings, AKHSD transcript was in low concentration as compared to white light where the transcript concentration was high. A 5 min red light pulse increased the transcript concentration significantly in contrast to 5 min far‐red light. The transcript concentration was reduced when 5 min red light was followed by a 5 min far‐red light pulse. The AK activity in dark‐raised seedlings is attributed to the presence of only one isoenzyme that is sensitive to lysine but insensitive to Ca++ and calmodulin (CAM). In both white and red light exposed seedlings, three isoenzymes of AK were detected. Two of these were sensitive to threonine while one was sensitive to lysine. Both of the threonine sensitive isoenzymes were activated by Ca++ and CAM. Also one of these isoenzymes seems to be located and synthesized in chloroplasts because its synthesis was completely inhibited by chloramphenicol but not by cycloheximide.
Degradation of an ubiquitin‐conjugated protein is associated with myoblast differentiation in primary cell culture
Authors: Gardrat Florence , Montel Valérie , Raymond Jacques , Azanza Jean‐Louis 
Published: July 2007

AbstractAt the early stages of myogenesis, myoblasts fuse to form multinucleated myotubes. This morphological differentiation is the result of dynamic changes in gene regulation and expression. The ubiquitin proteasome‐dependent pathway has been reported to play an important role in many aspects of cellular functions such as regulation of growth and cell cycle progression. In this study, we showed that the amount of mRNA's corresponding to the iota subunit of the 20S proteasome, the level of the S4 subunit of the 19S complex and the 20S and 26S proteasomes peptidase activities increased during myoblast fusion. Cell permeable 20S proteasome inhibitor prevented fusion with concomitant accumulation of ubiquitin‐conjugated protein. On the other hand, inhibition of ubiquitin ligase E3 enzymes prevented the formation of ubiquitin conjugate and decreased the fusion process. These results strongly support the involvement of the ubiquitin‐proteasome proteolytic pathway in the events leading to myoblast fusion.
Purification and characterization of a novel dipeptidyl peptidase from Dictyostelium discoideum
Authors: Choi Wai S. , Fu Qi , Jones Theodore H. D. 
Published: July 2007

AbstractA dipeptidyl peptidase (DPP) was purified to homogeneity using lys‐ala‐β‐naphthylamide, the standard substrate for DPP II. The enzyme is a monomer with a Mr of 70kDa, pl 5.2, and Km 5.0μM. Its terminal amino acid sequence was XXLLYAIQKRLF and was not identical to that of any known protein. Although initially considered to be a DPP II, the enzyme differed in some properties from classical DPP IIs. It had a pH optimum of 7.9, was not active on X‐pro‐naphthylamides, the usual substrates of mammalian DPP II, but was active on arg‐arg‐ and asp‐arg‐naphthylamides, substrates acted on by the DPP III class of enzymes. This enzyme therefore combines properties typical of both DPP II and III and differs from all previously described DPPs. Activity on lys‐ala‐β‐naphthylamide was most abundant during aggregation and its activity is consistent with processing specific peptides during development.
A Model of EcoRII Restriction Endonuclease Action: The Active Complex is Most Likely Formed by One Protein Subunit and One DNA Recognition Site
Authors: Karpova Elizaveta A. , Kubareva Elena A. , Shabarova Zoe A. 
Published: July 2007

AbstractTo elucidate the mechanism of interaction of restriction endonuclease Eco RII with DNA, we studied by native gel electrophoresis the binding of this endonuclease to a set of synthetic DNA‐duplexes containing the modified orcanonical recognition sequence 5‐d(CCA/TGG)‐3. All binding substrate or substrate analogues tested could be divided into two major groups: (i) duplexes that, at the interaction with endonuclease EcoRII, form two types of stable complexes on native gel in the absence of Mg+2 cofactor; (ii) duplexes that form only one type of complex, observed both in the presence and absence of Mg+2. Unlike the latter, duplexes under the first group can be hydrolyzed by endonuclease. Data obtained suggest that the active complex is most likely formed by one protein subunit and one DNA recognition sequence. A model of EcoRII endonuclease action is presented.
pp60v‐src Reactivation Inhibits Serum‐Induced Accumulation of Inositol Phosphates and Phosphatidylethanol in tsNRK
Authors: Kim Bo Yeon , Kim Jin Hee , Han Yoon Jeong , Ahn Soon Cheol , Kang Dae Ook , Oh Won Keun , Ko Hack Ryong , Lee Hyun Sun , Mheen Tae Ick , Ahn Jong Seog 
Published: July 2007

AbstractIn tsRSV‐infected NRK (tsNRK) cells, pp60v‐src reactivation by temperature‐shift from a nonpermissive temperature, 39 C, to a permissive one, 32 C, induced the production of inositol phosphates (IPt) and phosphatidylethanol (PEt). This was accompanied by an increase in membrane‐associated protein kinase C (PKC) activity in the absence of exogenous growth factors. However, with serum‐stimulation, the amounts of IPt and PEt at 32 C were less than those at 39 C. Pretreatment with PKC inhibitors, Ro‐31‐8220 and staurosporine, enhanced the accumulation of IPt but not of PEt at 32 C. The tyrosine phosphorylation of phospholipase C gamma1 (PLC gamma1) was increased either by serum or by pp60v‐src reactivation. These results suggest that serum transduces its signal through PLC gamma1 mediation, and that pp60v‐src, possibly through the PKC mediation, negatively affects serum‐induced PLC gamma1 activation.
Macromolecular Mimicry of Nucleic Acid and Protein
Authors: Pedersen Gitte Nautrup , Nyborg Jens , Clark Brian F. C. 
Published: July 2007

AbstractAlthough proteins and nucleic acids consist of different chemical components, proteins can mimic structures and possibly also functions of nucleic acids. Recently, structural mimicry was observed between two elongation factors in bacterial protein biosynthesis leading to the introduction of the concept of macromolecular mimicry. Macromolecular mimicry has further been proposed among initiation and release factors, thereby adding a new element to the description of protein synthesis in bacteria. Such mimicry has also been observed in other biological processes such as autoimmunity, DNA repair, and gene regulation, at both transcriptional and translational levels.
The p41 Fragment Story
Authors: Turk Dusan , Guncar Gregor , Turk Vito 
Published: July 2007

AbstractThe discovery of a fragment from the p41 form of invariant chain tightly bound to cathepsin L provided the first direct link between MHC class II molecules and the regulation of activity of lysosomal cysteine proteases. We recently determined the crystal structure of this p41 invariant chain fragment in complex with cathepsin L[EMBO J. 18, 793 803 (1999)]. This structure explains the specificity of the observed interactions and actually provides a tool, which can be utilized by means of molecular biology, to explore and understand the specificity of thyroglobulin type I domains and thus allow the design of specific inhibitors of papain‐like cysteine proteases. The structure further supports the hypothesis that the thyroglobulin type I and II domains present in various proteins, sometimes in multiple repeats, are regulatory elements of the processing of these proteins by proteolytic cleavage.
Use of Novel Bone Biopsy System to Study Molecular Effectst of Growth Hormone in Human Bone‐ A Pilot Study
Authors: Melhus Hakan , Astrom Gunnar , Ahlstrom Hakan , Burman Pia , Karlsson Anders , Ljunghall Sverker 
Published: July 2007

AbstractIn this study, we have examined whether a novel bone biopsy system combined with reverse transcription‐polymerase chain reaction (RT‐PCR) or differential display PCR (ddPCR) can be used to detect specific mRNAs induced by growth hormone (GH) in human bone. In a 58‐year‐old man with complete GH deficiency as a result of empty sella, bone biopsies were taken before, and 5 and 24h after administration of 24 recombinant human GH. Insulin‐like growth factor binding protein‐3 (IGFBP‐3) mRNA levels in this patient, measured in a semiquantitative RT‐PCR assay, increased about 40% 24 h after GH administration. This increase was not seen in a healthy control who did not receive GH, suggesting that the increase was an effect of GH rather than of the biopsy itself. Several differentially expressed mRNAs were detected by ddPCR. Thus, this pilot study suggests that our novel bone biopsy system may be suitable for in vivo studies of the molecular effects of substances with essential functions in human bone.
Phosphorylation‐Dephosphorylation of Retinoblastoma Protein Not Necessary for Passage through the Mammalian Cell Division Cycle
Authors: Cooper Stephen , Yu Chao , Shayman James Alan 
Published: July 2007

AbstractPhosphorylation of the retinoblastoma protein (Rb) during the G1‐phase of the mammalian cell division cycle is currently believed to be a controlling element regulating the passage of cells into S‐phase. We find, however, that the suspension‐grown cell lines U937, L1210, and MOLT‐4 contain exclusively hyperphosphorylated Rb. Furthermore, when adherent NIH3T3 cells are grown at very low densities to avoid overgrowth and contact inhibition, they also contain only hyperphosphorylated Rb. NIH3T3 cells exhibit hypophosphorylation when the cells are grown at moderate to high cell densities. We propose that cultures of adherent cells such as NIH3T3, when grown to moderate cell densities, are made up of two populations of cells: (a) cells that are relatively isolated and therefore growing exponentially without contact inhibition, and (b) cells that are growth‐inhibited by local cell density or contact inhibition. The common observation in adherent cell lines, that Rb is both hyper‐ and hypophosphorylated in the G1‐phase and only hyperphosphorylated in the S‐ and G2‐phases, is explained by the effects of cell density and contact inhibition. Thus, phosphorylation‐dephosphorylation of Rb protein during the G1 phase is not a necessary process during the NIH3T3, L1210, MOLT‐4, and U937 division cycles. We propose that phosphorylation‐dephosphorylation of Rb is independent of the division cycle and is primarily determined by growth conditions throughout the division cycle.
Caspases in Developmental Cell Death
Authors: Shearwin‐Whyatt Linda M. , Kumar Sharad 
Published: July 2007

AbstractCaspases are a family of evolutionarily conserved cysteine proteases that constitute the effector arm of the apoptotic machinery. Studies in Caenorhabditis elegans, Drosophila melanogaster, and mouse point to evolutionarily conserved caspase function in developmentally programmed cell death in metazoans. Whereas in the nematode all developmetal cell death is mediated by a single caspase,in Drosophila and the mouse some caspases appear to regulate cell death in a spatio‐temporally restricted manner. This article reviews what we currently know about the roles of various caspases in the execution of developmentally programmed cell death and what may be expected from future research in this field.
Involvement of ArcA and Fnr in Expression of Escherichia coli Thiol Peroxidase Gene
Authors: Kim Sung‐Jin , Han Young‐Hee , Kim Il‐Han , Kim Ha‐Kun 
Published: July 2007

AbstractTo explore the oxygen response regulators involved in thiol peroxidase gene (tpx) expression in Escherichia coli, we constructed a single‐copy tpx‐lacZ operon fusion and monitored tpx‐lacZ expression in various genetic backgrounds. Expression of the tpx‐lacZ fusion was increased 4‐fold by aerobic growth. Anaerobic expression of tpx‐lacZ in either Delta arcA or Delta fnr strains was 2.5‐fold depressed compared with that of the wild‐type strain. The results of immunoblotting experiments also demonstrated that ArcA and Fnr regulatory proteins repressed thiol peroxidase gene expression during anaerobic growth. Inspection of the tpx promoter region revealed putative binding sites for ArcA and Fnr. It thus appears that ArcA and Fnr function as repressors by blocking the binding of RNA polymerase to the tpx promoter in E. coli under anaerobic growth conditions.
Expression of a Human Serum Albumin Fragment (Consisting of Subdomains IA, IB, and IIA) and a Study of Its Properties
Authors: Park David S. , Petersen Charles E. , Ha Chung‐Eun , Harohalli Krishna , Feix Jimmy B. , Bhagavan Nadhipuram V. 
Published: July 2007

AbstractSite‐directed mutagenesis and a yeast expression system were used to synthesize a human serum albumin (HSA) fragment(amino acids 1‐297). The HSA fragment (half HSA) was evaluated with a number of biophysical techniques and found to be similar to the corresponding region in wild‐type HSA. Specifically, the circular dichroism spectra of half HSA and wild‐type HSA were superimposable, indicating that the highly alpha‐helical secondary structure of wild‐type HSA is preserved in half HSA. Additionally, half HSA was partially reactive with a polyclonal antibody against authentic HSA. Half HSA, which contains subdomain IIA, had an affinity for thyroxine and several thyroxine analogs, similar to that observed previously for wild‐type HSA. This study suggests that the production of recombinant HSA fragments will be useful for the study of HSA ligand interactions.
Effect of Rooperol on Collagen Synthesis and Cell Growth
Authors: Dietzsch Erin , Albrecht Carl F. d. V. , Parker M. Iqbal 
Published: July 2007

AbstractThe effect of rooperol on type I collagen synthesis in normal skin and lung fibroblasts and cell growth in normal and transformed fibroblasts was investigated. Low concentrations of rooperol selectively inhibited the growth of transformed cells while stimulating collagen synthesis in normal fibroblasts. Elevated collagen synthesis and deposition could impede tumour cell invasion and metastasis, implying that rooperol may be useful as an antimetastatic agent in the treatment of cancer.
Analysis of Protein Kinase C Isoforms Involved in the Activation of Laminin Receptor in Raw264.7 Macrophages
Authors: Oh Chun‐Do , Kang Shin‐Sung , Ha Mahn Joon , Chun Jang‐Soo 
Published: July 2007

AbstractAdherence of hematopoietic macrophages to a laminin (LM) substratum requires protein kinase C (PKC)‐dependent activation of LM receptor. This study was performed to analyze PKC isoform(s) leading to the activation of LM receptor during Raw264.7 macrophage‐like cell adhesion to a LM substratum. Raw264.7 cells expressed multiple PKC isoforms, including alpha, betaI, delta, epsilon, zeta, lambda/iota and mu. Among the PKC isoforms expressed, selective activation of PKC delta and epsilon was sufficient to induce cell adhesion to LM. PKC‐dependent cell adherence was blocked by the selective inhibition of PKC delta, suggesting that PKC delta was the responsible PKC isoform leading to activation of LM receptor. PKC delta appeared to activate LM receptor in an intact microfilament‐dependent pathway, because disruption of microfilament inhibited cell adhesion to LM without affecting PKC delta activation.
Proteolysis of Synaptobrevin, Syntaxin, and Snap‐25 in Alveolar Epithelial Type II Cells
Authors: Zimmerman Un‐Jin P. , Malek Syeda K. , Liu Lin , Li Hong Lan 
Published: July 2007

AbstractSynaptobrevin‐2, syntaxin‐1, and SNAP‐25 were identified in rat alveolar epithelial type II cells by Western blot analysis. Synaptobrevin‐2 was localized in the lamellar bodies, and syntaxin‐1 and SNAP‐25 were found in 0.4% Nonidet P40‐soluble and ‐insoluble fractions, respectively, of the type II cells. When the isolated type II cells were stimulated for secretion with calcium ionophore A23187 or with phorbol 12‐myristate 13‐acetate, these proteins were found to have been proteolyzed. Preincubation of cells with calpain inhibitor II (N‐acetylleucylleucylmethionine), however, prevented the proteolysis. Treatment of the cell lysate with exogenous calpain resulted in a time‐dependent decrease of these proteins. The data suggest that synaptobrevin, syntaxin, and SNAP‐25 are subject to proteolytic modification by activated calpain in intact type II cells stimulated for secretion.
Oxidative Stress and Calcium Homeostasis in Dystrophic Skin Fibroblasts
Authors: Degl'Innocenti Donatella , Pieri Alessandro , Rosati Fabiana , Ramponi Giampietro 
Published: July 2007

AbstractMuscular dystrophy is a genetic disease that affects primarily skeletal muscle. The dystrophin absence has been related to the degeneration of muscle fibres. Indirect evidences suggest that oxidative stress may play a role in the pathogenesis of the disease, but the significance and precise extent of this contribution is poorly understood. In this paper we show that Becker Muscular Dystrophy (BMD) and Duchenne Muscular Dystrophy (DMD) skin fibroblasts are more susceptible to H2O2 treatment than are fibroblasts from unaffected persons. In particular, we found that, in growing DMD skin fibroblasts, the oxidative treatment resulted in significantly reduced growing capacity. We also investigated the concentrations of intracellular calcium during H2O2 treatment. The intracellular free calcium concentration increased by 22%, 35%, and 40% in unaffected, BMD, and DMD fibroblasts, respectively. However, the increase of the intracellular free calcium concentration is not related, as previously hypothesized, to a reduction of acylphosphatase concentrations, which seem to be unaffected by the H2O2 treatment, but rather to reduced enzyme activity.
Specific Processing of Poly(ADP‐Ribose) Polymerase, Accompanied by Activation of Caspase‐3 and Elevation/Reduction of Ceramide/Hydrogen Peroxide Levels, During Induction of Apoptosis in Host HL‐60 Cells Infected by the Human Granulocytic Ehrlichiosis (HGE) Agent
Authors: Dipietrantonio Anna M. , Hsieh Tze‐Chen , Wu Joseph M. 
Published: July 2007

AbstractWe studied the mechanism by which the human granulocytic ehrlichiosis (HGE) agent induces programmed cell death (apoptosis) in human promyelocytic HL‐60 leukemia cells. Using several New York HGE isolates, we show that the HGE agent‐elicited apoptosis is accompanied by increased processing of nuclear enzyme poly(ADP‐ribose) polymerase (PARP), concurrent with a noticeable increase in caspase 3 activities. A marked increase in the amounts of the signaling molecule ceramide but not of diacylglycerol was also observed in HGE agent‐infected HL‐60 cells, compared with the amounts in uninfected controls. Simultaneous or prior treatment of infected HL‐60 cells with the ceramide synthase inhibitor fumonisin B1 did not affect the magnitude of infection by the intracellular pathogen, as determined by both the presence of morulae and the expression of its outer surface membrane protein, p44. These results suggest that the observed changes in ceramide are generated through the sphingomyelinase pathway and not by way of de novo synthesis of ceramide. We also assayed for changes in intracellular hydrogen peroxide and show that the HGE agent causes a decrease in its concentrations in infected cells.
Lysophosphatidic Acid and Sphingosine 1‐Phosphate: Two Lipid Villains Provoking Cardiovascular Diseases?
Authors: Siess Wolfgang , Essler Markus , Brandl Richard 
Published: July 2007

AbstractLysophosphatidic acid (LPA) and sphingosine 1‐phosphate (S1P) are potent bioactive lipids with specific and multiple effects on cells of the vessel wall and blood platelets. In this paper we suggest that these lipid molecules are involved in atherogenesis, pathological vasoconstriction, plaque rupture, and intravascular thrombus formation, which leads us to propose new strategies for the prevention and therapy of cardiovascular diseases. The conclusions are hypothetical, in that the studies were so far mainly carried out on isolated cells or cultured cells in vitro and the results were extrapolated to the situation in vivo.
Molecular Analysis of the Saccharomyces cerevisiae YHR076w Gene
Authors: Ramos C. W. , GÜldener U. , Klein S. , Hegemann J. H. , Gonzalez S. , RodrÍguez‐Medina J. R. 
Published: July 2007

AbstractOur results demonstrate that open reading frame (ORF) YHR076w on chromosome VIII of Saccharomyces cerevisiae that was previously described as a hypothetical gene is expressed. This ORF is transcribed as an mRNA of approximately 1,100 nucleotides. A 41.2‐kDa polypeptide and three others predicted to be modified forms of Yhr076wp are detected by Western blot with a Yhr076wp‐specific antibody. Promoter activity assays indicate that YHR076w transcription is regulated by carbon source and primarily by ethanol. Consistent with this observation, we have identified two potential ADR1 regulatory elements in the YHR076w upstream DNA region. Potential YAP1 and HSP elements are also identified in this region, suggesting other forms of regulation. YHR076w knockout strains do not exhibit any measurable growth or morphological phenotype under any conditions tested. However, increased YHR076w gene dosage confers a growth advantage to both wildtype and YHR076w knockout strains on 2% ethanol or 2% galactose medium in a low O2 growth environment. The fluorescence emitted by a Yhr076wp protein fusion to A. aquorin GFP colocalizes with the mitochondria in vivo.
Editorial Introduction to Louis Althusser's 'Letter to the Central Committee of the PCF, 18 March 1966'
Authors: Lewis William 
Published: July 2007

AbstractAs an accompaniment to the translation into English of Louis Althusser's 'Letter to the Central Committee of the PCF, March 18th, 1966', this note provides the historical and theoretical context necessary to understand Althusser's 'anti-humanist' interventions into French Communist Party policy decisions during the mid-1960s. Because nowhere else in Althusser's published writings do we see as clearly the political stakes involved in his philosophical project, nor the way in which this project evolved from a 'theoreticist' pursuit into a more practical one, the note also argues that the letter is of importance to Althusser scholars, to historians of Marxist thought, and to those interested in the relevance of Althusser's work to contemporary Marxist philosophy.
Strategic planning and forecasting
Authors: Naylor Thomas H. 
Published: July 2007

AbstractThis paper examines the role of forecasting in strategic planning through the use of analytical portfolio models and corporate simulation models. It also outlines a conceptual framework on which it may be possible to develop a theory of strategic planning—namely, microeconomic theory. It, finally, describes a practical application of this theoretical framework, known as the strategy matrix. It concludes by noting the importance of forecasting as an input to the strategy matrix.