Showing papers by "Washington State University published in 1998"
TL;DR: In this article, the authors consider the combination of the type and structure of relationships and how this embeddedness perspective relates to social contagion and conspiracies, and generate propositions concerning types of relationships (strength, multiplexity, asymmetry, and status) and the structural holes, centrality, and density.
Abstract: Recent models of unethical behavior have begun to examine the combination of characteristics of individuals, issues, and organizations. We extend this examination by addressing a largely ignored perspective that focuses on the relationships among actors. Drawing on social network analysis, we generate propositions concerning types of relationships (strength, multiplexity, asymmetry, and status) and the structure of relationships (structural holes, centrality, and density). We also consider the combination of the type and structure of relationships and how this embeddedness perspective relates to social contagion and conspiracies.
941 citations
TL;DR: It is demonstrated that the P1/HC-Pro polyprotein encoded by tobacco etch virus functions as a suppressor of PTGS, which reveals that plant viruses can condition enhanced susceptibility within a host through interdiction of a potent defense response.
831 citations
TL;DR: Analysis of rapid evolution as an ecological process has the potential to make evolutionary ecology one of the most central of applied biological sciences.
Abstract: Rapid evolution of interspecific interactions (during a timespan of about 100 years) has the potential to be an important influence on the ecological dynamics of communities. However, despite the growing number of examples, rapid evolution is still not a standard working hypothesis for many ecological studies on the dynamics of population structure or the organization of communities. Analysis of rapid evolution as an ecological process has the potential to make evolutionary ecology one of the most central of applied biological sciences.
831 citations
TL;DR: In this paper, a 9-item Likert-type scale was developed to measure consumer skepticism toward advertising, defined as the general tendency toward disbelief of advertising claims, was hypothesized to be a basic marketplace belief that varies across individuals and is related to general persuasability.
819 citations
TL;DR: Sertoli cells are the somatic cells of the testis that are essential for testis formation and spermatogenesis and the action of FSH minimally serves to promote sperMatogenic output by increasing the number of SERToli cells.
805 citations
TL;DR: Comparison of model results with drought experiments in sunflower and water birch indicated that stomatal regulation of E reflected the species' hydraulic potential for extracting soil water, and that the more sensitiveStomatal response of water Birch to drought was necessary to avoid hydraulic failure.
Abstract: Hydraulic conductivity (K) in the soil and xylem declines as water potential (psi) declines. This results in a maximum rate of steady-state transpiration (E(crit)) and corresponding minimum leaf psi (psi(crit)) at which K has approached zero somewhere in the soil-leaf continuum. Exceeding these limits causes water transport to cease. A model determined whether the point of hydraulic failure (where K = 0) occurred in the rhizosphere or xylem components of the continuum. Below a threshold of root:leaf area (A(R):A(L)), the loss of rhizosphere K limited E(crit) and psi(crit). Above the threshold, loss of xylem K from cavitation was limiting. The A(R):A(L) threshold ranged from > 40 for coarse soils and/or cavitation-resistant xylem to < 0.20 in fine soils and/or cavitation-susceptible xylem. Comparison of model results with drought experiments in sunflower and water birch indicated that stomatal regulation of E reflected the species' hydraulic potential for extracting soil water, and that the more sensitive stomatal response of water birch to drought was necessary to avoid hydraulic failure. The results suggest that plants should be xylem-limited and near their A(R):A(L) threshold. Corollary predictions are (1) within a soil type the A(R):A(L) should increase with increasing cavitation resistance and drought tolerance, and (2) across soil types from fine to coarse the A(R):A(L) should increase and maximum cavitation resistance should decrease.
698 citations
TL;DR: It is indicated that jasmonate is essential for plant defense against Pythium and, because of the high exposure of plant roots to Pythium inoculum in soil, may well be fundamental to survival of plants in nature.
Abstract: To investigate the role of jasmonate in the defense of plants against fungal pathogens, we have studied a mutant of Arabidopsis, fad3–2 fad7–2 fad8, that cannot accumulate jasmonate. Mutant plants were extremely susceptible to root rot caused by the fungal root pathogen Pythium mastophorum (Drechs.), even though neighboring wild-type plants were largely unaffected by this fungus. Application of exogenous methyl jasmonate substantially protected mutant plants, reducing the incidence of disease to a level close to that of wild-type controls. A similar treatment with methyl jasmonate did not protect the jasmonate-insensitive mutant coi1 from infection, showing that protective action of applied jasmonate against P. mastophorum was mediated by the induction of plant defense mechanisms rather than by a direct antifungal action. Transcripts of three jasmonate-responsive defense genes are induced by Pythium challenge in the wild-type but not in the jasmonate-deficient mutant. Pythium species are ubiquitous in soil and root habitats world-wide, but most (including P. mastophorum) are considered to be minor pathogens. Our results indicate that jasmonate is essential for plant defense against Pythium and, because of the high exposure of plant roots to Pythium inoculum in soil, may well be fundamental to survival of plants in nature. Our results further indicate that the fad3–2 fad7–2 fad8 mutant is an appropriate genetic model for studying the role of this important signaling molecule in pathogen defense.
568 citations
TL;DR: The authors develop guidelines to assist managers in selecting or modifying logos to achieve their corporate image goals and identify logos that meet high-recognition, low-investment, and high-image communication objectives.
Abstract: The authors develop guidelines to assist managers in selecting or modifying logos to achieve their corporate image goals. An empirical analysis of 195 logos, calibrated on 13 design characteristics...
533 citations
TL;DR: Years of studies with selective ligands for NE and 5-HT transporters have demonstrated that such drugs lack the ability to maintain self-administration behavior in animals or to produce euphoria in humans.
505 citations
TL;DR: In this article, a 3D mesoscopic model to simulate the collective dynamic behavior of a large number of curved dislocations of finite lengths has been developed for the purpose of analyzing deformation patterns and instabilities, including the formation of dislocation cell structures.
446 citations
TL;DR: The multi-step, multi-product reactions catalyzed by the sesquiterpene synthases from grand fir are among the most complex of any terpenoid cyclase thus far described.
TL;DR: The authors found that peer friendships experienced three primary transitions: from coworker/acquaintance to friend, friend to close friend, and close friend-to-almost best friend, which was associated primarily with life events, work-related problems, and the passage of time.
Abstract: This paper reports the results of our analysis of interviews with 38 individuals (representing 19 peer friendships) in which we explored factors and communication changes associated with the development of workplace friendships. We found that peer friendships experienced three primary transitions: from coworker/acquaintance‐to‐friend, friend‐to‐close friend, and close friend‐to‐almost best friend. The co‐worker‐to‐friend transition was perceived to be caused primarily by working together in close proximity, sharing common ground, and extra‐organizational socializing. Communication at this transition became broader, yet remained relatively superficial. The friend‐to‐close friend transition was associated primarily with problems in one's personal and work experiences. Communication at this transition became broader, more intimate, and less cautious. The close friend‐to‐almost best friend transition was associated primarily with life events, work‐related problems, and the passage of time. Communication becam...
TL;DR: The characterization of esk1 mutants and results from other mutants suggest that distinct signaling pathways activate different aspects of cold acclimation and that activation of one pathway can result in considerable freezing tolerance without activation of other pathways.
Abstract: Temperate plants develop a greater ability to withstand freezing in response to a period of low but nonfreezing temperatures through a complex, adaptive process of cold acclimation. Very little is known about the signaling processes by which plants perceive the low temperature stimulus and transduce it into the nucleus to activate genes needed for increased freezing tolerance. To help understand the signaling processes, we have isolated mutants of Arabidopsis that are constitutively freezing-tolerant in the absence of cold acclimation. Freezing tolerance of wild-type Arabidopsis was increased from −5.5°C to −12.6°C by cold acclimation whereas the freezing tolerance of 26 mutant lines ranged from −6.8°C to −10.6°C in the absence of acclimation. Plants with mutations at the eskimo1 (esk1) locus accumulated high levels of proline, a compatible osmolyte, but did not exhibit constitutively increased expression of several cold-regulated genes involved in freezing tolerance. RNA gel blot analysis suggested that proline accumulation in esk1 plants was mediated by regulation of transcript levels of genes involved in proline synthesis and degradation. The characterization of esk1 mutants and results from other mutants suggest that distinct signaling pathways activate different aspects of cold acclimation and that activation of one pathway can result in considerable freezing tolerance without activation of other pathways.
01 Jan 1998
TL;DR: Respondent-friendly questionnaire design is aimed explicitly at reducing three of the four types of error that typically prevent accurate surveys from being done, i.e., nonresponse, measurement, and coverage of the survey population.
Abstract: Summary and Conclusions Use of the World Wide Web to conduct surveys provides enormous opportunities as well aschallenges. The cost advantages of collecting large amounts of data at very little cost means thatits use will escalate rapidly. At the same time, maintaining quality, whereby the results ofsurveys can be generalized to a large population is far from automatic.Respondent-friendly questionnaire design, found important to improving response to self-administered mail questionnaires, is also important for the development of web questionnaires.However, in a web context the term takes on a broader meaning. A respondent-friendly webquestionnaire is one that interfaces effectively with the wide variety of computers and browserspossessed by respondents. It also makes other aspects of the response task easy and interestingfor the respondent to complete. Respondent-friendly designed is aimed explicitly at reducingthree of the four types of error that typically prevent accurate surveys from being done, i.e.,nonresponse, measurement, and coverage of the survey population.Three important criteria for achieving respondent-friendly design have been stated. Theyinclude, first, compliancy with technology available to the respondent. If a browser cannotrecognize the programmed information being sent to it, the respondent cannot receive it.Questionnaires that use advanced programming that takes longer transmission times and requiresmore advanced browsers may result in unintended coverage and nonresponse error. A secondcriterion is the necessity of bridging between the logic by which respondents expect a question-naire to operate and the logic associated with operating a computer. It’s this connection thatprovides a questionnaire design challenge not previously faced by survey methodologists. Inaddition to these criteria, web designers must also consider the high likelihood that coverageproblems will require that most quality web surveys, for the foreseeable future, will require themixing of survey modes, whereby some respondents are surveyed by mail or telephone whileothers are surveyed via the web.
TL;DR: These results demonstrate that after internalization S. aureus escapes the endosome and induces apoptosis in nonprofessional phagocytes.
Abstract: We examined the invasion of an established bovine mammary epithelial cell line (MAC-T) by a Staphylococcus aureus mastitis isolate to study the potential role of intracellular survival in the persistence of staphylococcal infections. S. aureus cells displayed dose-dependent invasion of MAC-T cells and intracellular survival. An electron microscopic examination of infected cells indicated that the bacteria induced internalization via a mechanism involving membrane pseudopod formation and then escaped into the cytoplasm following lysis of the endosomal membrane. Two hours after the internalization of S. aureus, MAC-T cells exhibited detachment from the matrix, rounding, a mottled cell membrane, and vacuolization of the cytoplasm, all of which are indicative of cells undergoing programmed cell death (apoptosis). By 18 h, the majority of the MAC-T cell population exhibited an apoptotic morphology. Other evidence for apoptosis was the generation of MAC-T cell DNA fragments differing in size by increments of approximately 180 bp and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling of the fragmented nuclear DNA of the infected host cells. These results demonstrate that after internalization S. aureus escapes the endosome and induces apoptosis in nonprofessional phagocytes.
TL;DR: The cloning from peppermint and heterologous expression in Escherichia coli of 1-deoxy-D-xylulose-5-phosphate synthase appears to represent a novel class of highly conserved transketolases and likely plays a key role in the biosynthesis of plastid-derived isoprenoids essential for growth, development, and defense in plants.
Abstract: Isopentenyl diphosphate, the common precursor of all isoprenoids, has been widely assumed to be synthesized by the acetate/mevalonate pathway in all organisms. However, based on in vivo feeding experiments, isopentenyl diphosphate formation in several eubacteria, a green alga, and plant chloroplasts has been demonstrated very recently to originate via a mevalonate-independent route from pyruvate and glyceraldehyde 3-phosphate as precursors. Here we describe the cloning from peppermint (Mentha × piperita) and heterologous expression in Escherichia coli of 1-deoxy-d-xylulose-5-phosphate synthase, the enzyme that catalyzes the first reaction of this pyruvate/glyceraldehyde 3-phosphate pathway. This synthase gene contains an ORF of 2,172 base pairs. When the proposed plastid targeting sequence is excluded, the deduced amino acid sequence indicates the peppermint synthase to be about 650 residues in length, corresponding to a native size of roughly 71 kDa. The enzyme appears to represent a novel class of highly conserved transketolases and likely plays a key role in the biosynthesis of plastid-derived isoprenoids essential for growth, development, and defense in plants.
01 Jan 1998
Proceedings Article•
01 Jan 1998
TL;DR: The role of disorder-to-order transitions in protein binding has been investigated in this paper, where it is shown that these transitions enable alternative packing interactions between side chains to accommodate the different binding targets.
Abstract: Observations going back more than 20 years show that regions in proteins with disordered backbones can play roles in their binding to other molecules; typically, the disordered regions become ordered upon complex formation. Thought-experiments with Schulz Diagrams, which are defined herein, suggest that disorder-to-order transitions are required for natural selection to operate separately on affinity and specificity. Separation of affinity and specificity may be essential for fine-tuning the molecular interaction networks that comprise the living state. For low affinity, high specificity interactions, our analysis suggests that natural selection would parse the amino acids conferring flexibility in the unbound state from those conferring specificity in the bound state. For high affinity, low specificity or for high affinity, multiple specificity interactions, our analysis suggests that the disorder-to-order transitions enable alternative packing interactions between side chains to accommodate the different binding targets. Disorder-to-order transitions upon binding also have significant kinetic implications as well, by having complex effects on both on- and off-rates. Current data are insufficient to decide on these proposals, but sequence and structure analysis on two examples support further investigations of the role of disorder-to-order transitions upon binding.
TL;DR: Tetrasomic inheritance, apparently related to the tetraploid ancestry of salmonid fishes, was detected at one simple sequence repeat locus and suggested by the presence of one extremely large linkage group that appeared to consist of two smaller groups linked at their tips.
Abstract: We report the first detailed genetic linkage map of rainbow trout (Oncorhynchus mykiss). The segregation analysis was performed using 76 doubled haploid rainbow trout produced by androgenesis from a hybrid between the "OSU" and "Arlee" androgenetically derived homozygous lines. Four hundred and seventy-six markers segregated into 31 major linkage groups and 11 small groups (< 5 markers/group). The minimum genome size is estimated to be 2627.5 cM in length. The sex-determining locus segregated to a distal position on one of the linkage groups. We analyzed the chromosomal distribution of three classes of markers: (1) amplified fragment length polymorphisms, (2) variable number of tandem repeats, and (3) markers obtained using probes homologous to the 5' or 3' end of salmonid-specific small interspersed nuclear elements. Many of the first class of markers were clustered in regions that appear to correspond to centromeres. The second class of markers were more telomeric in distribution, and the third class were intermediate. Tetrasomic inheritance, apparently related to the tetraploid ancestry of salmonid fishes, was detected at one simple sequence repeat locus and suggested by the presence of one extremely large linkage group that appeared to consist of two smaller groups linked at their tips. The double haploid rainbow trout lines and linkage map present a foundation for further genomic studies.
TL;DR: Using dominant-negative approaches in cardiac myocytes, both the titin Z1-Z2 domains and titin-cap are shown to be required for the structural integrity of sarcomeres, suggesting that their interaction is critical in titin filament–regulated sarcomeric assembly.
Abstract: Titin is a giant elastic protein in vertebrate striated muscles with an unprecedented molecular mass of 3–4 megadaltons. Single molecules of titin extend from the Z-line to the M-line. Here, we define the molecular layout of titin within the Z-line; the most NH2-terminal 30 kD of titin is located at the periphery of the Z-line at the border of the adjacent sarcomere, whereas the subsequent 60 kD of titin spans the entire width of the Z-line. In vitro binding studies reveal that mammalian titins have at least four potential binding sites for α-actinin within their Z-line spanning region. Titin filaments may specify Z-line width and internal structure by varying the length of their NH2-terminal overlap and number of α-actinin binding sites that serve to cross-link the titin and thin filaments. Furthermore, we demonstrate that the NH2-terminal titin Ig repeats Z1 and Z2 in the periphery of the Z-line bind to a novel 19-kD protein, referred to as titin-cap. Using dominant-negative approaches in cardiac myocytes, both the titin Z1-Z2 domains and titin-cap are shown to be required for the structural integrity of sarcomeres, suggesting that their interaction is critical in titin filament–regulated sarcomeric assembly.
TL;DR: Although an abundance of anecdotal and journalistic articles about Asian Americans as a model minority has appeared in the past two decades, a review of the literature revealed surprisingly few empirical studies.
Abstract: Although an abundance of anecdotal and journalistic articles about Asian Americans as a model minority has appeared in the past two decades, a review of the literature revealed surprisingly few emp...
TL;DR: Using photoelectron spectroscopy of size-selected clusters, the authors studied the electronic structure evolution of the Al $3s$- and $3p$-derived bands and observed that the Al bands evolve and broaden with cluster size and begin to overlap at the same time.
Abstract: Using photoelectron spectroscopy of size-selected ${\mathrm{Al}}_{x}^{\ensuremath{-}}$ $(x\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1--162)$ clusters, we studied the electronic structure evolution of ${\mathrm{Al}}_{x}$ and observed that the Al $3s$- and $3p$-derived bands evolve and broaden with cluster size and begin to overlap at ${\mathrm{Al}}_{9}$. Direct spectroscopic signatures were obtained for electron shell structures with spherical shell closings at ${\mathrm{Al}}_{11}^{\ensuremath{-}}$, ${\mathrm{Al}}_{13}^{\ensuremath{-}}$, ${\mathrm{Al}}_{19}^{\ensuremath{-}}$, ${\mathrm{Al}}_{23}^{\ensuremath{-}}$, ${\mathrm{Al}}_{35}^{\ensuremath{-}}$, ${\mathrm{Al}}_{37}^{\ensuremath{-}}$, ${\mathrm{Al}}_{46}$, ${\mathrm{Al}}_{52}$, ${\mathrm{Al}}_{55}^{\ensuremath{-}}$, ${\mathrm{Al}}_{56}$, ${\mathrm{Al}}_{66}$, and ${\mathrm{Al}}_{73}^{\ensuremath{-}}$. The electron shell effect diminishes above ${\mathrm{Al}}_{75}$ and new spectral features appearing in ${\mathrm{Al}}_{x}^{\ensuremath{-}}$ $(xg100)$ suggest a possible geometrical packing effect in large clusters.
TL;DR: High- as compared to low-hope women reported more hope-related coping responses in four separate imagined phases of cancer (prevention/risk, detection, temporal course, and impact), and these relationships remained when shared variances related to previous academic achievement, knowledge about cancer, experience with cancer, and negative affectivity were removed.
Abstract: The relations of dispositional hope to various self-reported cancer-related coping activities were examined in 115 college women. Dispositionally high- as compared to low-hope women were more knowledgeable about cancer, and this relationship remained when the shared variances due to previous academic achievement, experience with cancer among family or friends, and positive and negative affectivity were removed. Additionally, high- as compared to low-hope women reported more hope-related coping responses in four separate imagined phases of cancer (prevention/risk, detection, temporal course, and impact), and these relationships remained when shared variances related to previous academic achievement, knowledge about cancer, experience with cancer, and negative affectivity were removed. Hope is discussed as means of maintaining a "fighting spirit" for coping with cancer.
TL;DR: In this article, the role of surface-active polysaccharides in the formation of transparent exopolymer particles (TEP) by bubble adsorption in seawater was examined.
Abstract: Experiments were performed to examine the role of surface-active polysaccharides in the formation of transparent exopolymer particles (TEP) by bubble adsorption in seawater. Filtered (1 .O pm, 0.45 pm) and ultrafiltered (0.1 pm, 100 kDa, and 10 kDa) seawater samples were bubbled in a glass foam tower. The neutral sugar composition, concentration of TEP, and concentration of surface-active carbohydrates in generated foam samples were determined. Three different surface seawater samples (Monterey Bay, California; Shannon Point, Anacortes, Washington; and East Sound, Orcas Island, Washington) were used in the experiments. Significant concentrations of pre-existing and new TEP were extracted into foam by bubble adsorption. Newly generated TEP accounted for 28-52% of the TEP collected in the foam samples by bubbling l.O-pm-filtered samples. Neutral sugar composition analyses of foam samples derived as a function of bubbling time indicated that two types of surface-active carbohydrates were extracted by bubble adsorption: highly surface-active carbohydrates, which were extracted initially, and less surfaceactive carbohydrates. As in our previous mesocosm study (Mopper et al. 1995), highly surface-active polysaccharides were enriched in deoxysugars (fucose and rhamnose), whereas the less surface-active polysaccharides and residual (bubble-stripped) water were glucose rich. In addition, the highly surface-active fraction was strongly enriched in covalently bound sulfate. The concentrations of TEP and surface-active carbohydrates that were extracted into the foam both decreased sharply with decreasing filter size used to filter samples prior to bubbling, in agreement with theoretical considerations. The results of this study suggest that bubble adsorption of sulfate-rich surface-active carbohydrates is an important pathway for the formation of TEP in surface waters, especially during algal blooms.
TL;DR: Molecular analysis indicates that the gene mutated is Bclw, a death-protecting member of the Bcl2 family, which appears to be restricted to elongating spermatids and Sertoli cells in the testis.
Abstract: To identify genes required for mammalian spermatogenesis, we screened lines of mutant mice created using a retroviral genetrap system1 for male infertility. Homozygous ROSA41 male mice exhibit sterility associated with progressive testicular degeneration. Germ-cell defects are first observed at 19 days post-natal (p19). Spermatogenesis is blocked during late spermiogenesis in young adults. Gradual depletion of all stages of germ cells results in a Sertoli-cell-only phenotype by approximately six months of age. Subsequently, almost all Sertoli cells are lost from the seminiferous tubules and the Leydig cell population is reduced. Molecular analysis indicates that the gene mutated is Bclw, a death-protecting member of the Bcl2 family. The mutant allele of Bclw in ROSA41 does not produce a Bclw polypeptide. Expression of Bclw in the testis appears to be restricted to elongating spermatids and Sertoli cells. Potential roles for Bclw in testicular function are discussed.
TL;DR: Indistinguishable pulsed-field gel electrophoresis patterns of XbaI digested chromosomal DNA and Shiga toxin types were observed for bovine and water-trough isolates from two farms and for one equine and two bovines from one farm.
TL;DR: It is postulate that different species of fluorescent pseudomonads have similar genetic systems that confer the ability to synthesize PCA, and two new genes were cloned and sequenced that are homologous to phzA and phzB, respectively.
Abstract: Pseudomonas fluorescens 2-79 produces the broad-spectrum antibiotic phenazine-1-carboxylic acid (PCA), which is active against a variety of fungal root pathogens. In this study, seven genes designated phzABCDEFG that are sufficient for synthesis of PCA were localized within a 6.8-kb BglII-XbaI fragment from the phenazine biosynthesis locus of strain 2-79. Polypeptides corresponding to all phz genes were identified by analysis of recombinant plasmids in a T7 promoter/polymerase expression system. Products of the phzC, phzD, and phzE genes have similarities to enzymes of shikimic acid and chorismic acid metabolism and, together with PhzF, are absolutely necessary for PCA production. PhzG is similar to pyridoxamine-5*-phosphate oxidases and probably is a source of cofactor for the PCA-synthesizing enzyme(s). Products of the phzA and phzB genes are highly homologous to each other and may be involved in stabilization of a putative PCA-synthesizing multienzyme complex. Two new genes, phzX and phzY, that are homologous to phzA and phzB, respectively, were cloned and sequenced from P. aureofaciens 30-84, which produces PCA, 2-hydroxyphenazine-1-carboxylic acid, and 2-hydroxyphenazine. Based on functional analysis of the phz genes from strains 2-79 and 30-84, we postulate that different species of fluorescent pseudomonads have similar genetic systems that confer the ability to synthesize PCA. Certain members of the genus Pseudomonas produce diverse low-molecular-weight (“secondary”) metabolites including nitrogen-containing heterocyclic pigments known as phenazine compounds (5, 19). Phenazines are synthesized by a limited number of bacterial genera including Pseudomonas, Burkholderia, Brevibacterium, and Streptomyces (38). Almost all phenazines exhibit broad-spectrum activity against various species of bacteria and fungi (32). This activity is connected with the ability of phenazine compounds to undergo oxidation-reduction transformations and thus cause the accumulation of toxic superoxide radicals in the target cells (15). Some phenazine compounds can act as bacterial virulence factors. For example, pyocyanin, produced by the opportunistic pathogen Pseudomonas aeruginosa during cystic fibrosis, has been shown to inhibit the ciliary function of respiratory epithelial cells (40). Phenazine antibiotics produced by the biocontrol strains P. fluorescens 2-79 and P. aureofaciens 30-84 are major factors in the ability of these strains to inhibit the growth of fungal root pathogens. Moreover, studies involving phenazine-deficient mutants have clearly demonstrated that antibiotic production in natural habitats plays an important role in the ecological competence and long-term survival of these strains in the environment (21). Over 50 naturally occurring phenazine compounds have been described, and certain bacterial producers are able to synthesize mixtures of as many as 10 different phenazine derivatives at one time (32, 38). Growth conditions
TL;DR: A role for the tandem arginines in the unique diphosphate migration step accompanying formation of the intermediate 3S-linalyl diph phosphate and preceding the final cyclization reaction catalyzed by the monoterpene synthases is indicated.
Abstract: The monoterpene cyclase limonene synthase transforms geranyl diphosphate to a monocyclic olefin and constitutes the simplest model for terpenoid cyclase catalysis. (−)-4S-Limonene synthase preprotein from spearmint bears a long plastidial targeting sequence. Difficulty expressing the full-length preprotein in Escherichia coli is encountered because of host codon usage, inclusion body formation, and the tight association of bacterial chaperones with the transit peptide. The purified preprotein is also kinetically impaired relative to the mixture of N-blocked native proteins produced in vivo by proteolytic processing in plastids. Therefore, the targeting sequence, that precedes a tandem pair of arginines (R58R59) which is highly conserved in the monoterpene synthases, was removed. Expression of this truncated protein, from a vector that encodes a tRNA for two rare arginine codons (pSBET), affords a soluble, tractable ‘pseudomature' form of the enzyme that is catalytically more efficient than the native spec...
TL;DR: It is proposed that the pharmacological neuroadaptations predominate in the manifestation of cocaine-induced paranoia, while the changes derived from learning may provide more critical underpinnings for cocaine craving and relapse.
Abstract: Sensitization to cocaine refers to the behavioral model of cocaine addiction where the motor stimulant effect of cocaine is augmented for months after discontinuing a regimen of repeated cocaine injections. There has been speculation that the neuroadaptations mediating this sensitization phenomenon may, in part, underlie the behavioral changes produced by chronic cocaine abuse, including paranoia, craving and relapse. Criteria are proposed that may assist in determining which neuroadaptations are most relevant in this regard. Using these criteria, a model is presented that endeavors to incorporate neuroadaptations issuing directly from the pharmacological effects of cocaine and those arising from learned associations the organism makes with the cocaine injection procedure and pharmacological actions. It is proposed that the pharmacological neuroadaptations predominate in the manifestation of cocaine-induced paranoia, while the changes derived from learning may provide more critical underpinnings for cocaine craving and relapse.
TL;DR: In this article, naturallyoccurring iron minerals, goethite and magnetite, were used to catalyze hydrogen peroxide and initiate Fenton-like reaction of silica sand contaminated with diesel and/or kerosene in batch system.