Non-competitive Process Research Articles

A Link between Species Abundance and Plant Strategies for Semi-Natural Dry Grasslands.

Due of the potential of species to determine ecosystem properties, it is important to understand how species abundance influences community assembly. Using vegetation surveys on 35 dry grasslands in north-east Slovenia, we defined dominant (8) and subordinate (61) plant species. They were compared on 14 traits to test for differences in community-weighted mean (CWM) and functional diversity (FD). We found that dominants and subordinates differed strongly in their functional traits. Dominants showed higher leaf dry matter content and a more pronounced stress tolerance strategy and were all clonal with a large proportion of species with rhizomes and a rich bud bank, while other species showed a higher specific leaf area, a longer flowering period and more ruderals. For most traits, FD was higher in subordinates. Our results suggest that dominants drive community structure by limited susceptibility to non-competitive processes. Dominants may have positive effects on subordinates by mitigating environmental stressors. Subordinates are able to assemble together by being dissimilar and use different fine-scale niches that are engineered and homogenised by dominants. Our results show that there are fundamental differences in the relative importance of ecological processes between dominant and subordinate plants in species-rich grasslands, which is also important for their conservational management.

One-Pot Environmentally Friendly Synthesis of Nanomaterials Based on Phytate-Coated Fe3O4 Nanoparticles for Efficient Removal of the Radioactive Metal Ions 90Sr, 90Y and (UO2)2+ from Water.

We report the fast (three minutes) synthesis of green nanoparticles based on nanoparticles coated with the natural organic receptor phytate for the recognition and capture of 90Sr, 90Y, and (UO2)2+. The new material shows excellent retention for (UO2)2+, 97%; these values were 73% and 100% for 90Sr and 90Y, respectively. Recovery of the three radioactive metal ions occurs through a non-competitive process. The new hybrid material is harmless, easy to prepare, and immobilizes these radioactive contaminants in water with great efficiency.

Transforming Lives of Former Foster Youths: A Campus-Based Support Program Grounded in Social Work Values.

Support programs to improve higher education outcomes for former foster youths have emerged in the past 20 years, but literature to guide their development and implementation is limited. This conceptual article presents the program logic model for ACE [Achieving College Excellence] Scholars Services, the comprehensive, campus-based program supporting former foster youths grounded in social work values at California State University San Marcos (CSUSM). ACE has a noncompetitive application process that accepts an unrestricted number of students, known as ACE Scholars. To focus on the unique needs of former foster youths, students who are on probation, experiencing homeless, and unaccompanied minors are included if they have also experienced foster care. Funded by private donors, the Center for ACE Scholars on CSUSM's campus provides an inviting, welcoming space that reflects the inclusive support ACE Scholars receive. By increasing educational attainment and opportunities for this vulnerable population, ACE aims to improve outcomes for former foster youths and their next generation. Articulating this program logic model provides implications for developing and implementing support programs for former foster youths on college campuses and sets the foundation for evaluating the impact of ACE Scholars Services.

Reducing agents assisted fed-batch fermentation to enhance ABE yields

Acetone-butanol-ethanol (ABE) fermentation process is a promising bioenergy option amid rising concerns over the environmental impact of fossil fuel usage. However, the commercialization of the ABE process has been marred by challenges of low product yield and titer, thereby non-competitive process economics. Here, we coupled cost competitive reducing agents with a controlled feeding strategy to improve both product titer and yield. Reducing agents promote cofactor dependent butanol production, while fed-batch operation enhances glucose consumption, final ABE titer, and partly mitigates product toxicity. The effects of ascorbic acid, L-cysteine, and dithiothreitol (DTT) on ABE fed-batch production using Clostridium acetobutylicum was investigated in current study. NADH, ATP, extracellular amino acid secretion, and NADH-dependent butanol dehydrogenase (BDH) assays were performed to study the metabolic modifications triggered by reducing agents. Incidentally, L-cysteine and DTT improved ABE solvent titer by 2-fold, producing 24.33 and 22.98 g/L ABE with solvent yields of 0.38 and 0.37 g/g, respectively. Elevated NADH, BDH, and ATP levels in fermentation broth reflected in enhanced ABE titer and yield. Furthermore, histidine secretion emerged as an important factor in Clostridial acid stress tolerance in this study. The results demonstrate that addition of reducing agents in fed-batch ABE fermentation operation enables efficient utilization of glucose with significant improvement in solvent production.

Role of Herba Pyrolae Essential Oil in Skin Aging and Their Inhibition of Free Radicals

Essential oil of Herba pyrolae, a Chinese herbal medicine, has been suggested to exhibit anti-aging effects. To understand underlying mechanism, we have examined its effect on inhibition of two free radicals (2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) and tyrosinase. The half maximal inhibitory concentration (IC50) of the essential oil was 0.1045 mg/mL for DPPH, while that for ABTS was 0.3961 mg/mL. In addition, the essential oil inhibited both monophenolase and diphenolase activities of tyrosinase. Further examination of the tyrosinase inhibition mechanism and kinetics showed that the diphenolase activity inhibition by H. pyrolae essential oil was a non-competitive reversible process. These data suggest possible mechanism(s) underlying anti-aging effects of H. pyrolae essential oil.

The Adsorptions of Three Licorice Derivatives by Multi-walled Carbon Nanotubes

The adsorptions of three licorice derivatives including,isoliquiritin,liquiritin and glycyrrhizic acid on multi-walled carbon nanotubes(MWNTs),were investigated using UV and HPLC techniques.The effects of adsorption time,initial concentration,solution volume and its pH value on the adsorption of ciprofloxacin are examined.MWNTs have totally different adsorptive capacities toward the three main components.In the multi-component competitive adsorption examination,a noncompetitive adsorption process was observed.The adsorption capacity of MWNTs for isoliquiritin is higher than those for liquiritin and glycyrrhizic acid.MWNTs may be potentially applied to the separation and purification of isoliquiritins.

Mechanism of cytochrome P450-3A inhibition by ketoconazole

Ketoconazole is extensively used as an index inhibitor of cytochrome P450-3A (CYP3A) activity in vitro and in vivo, but the mechanism of ketoconazole inhibition of CYP3A still is not clearly established. Inhibition of metabolite formation by ketoconazole (seven concentrations from 0.01 to 1.0 µm) was studied in human liver microsomes (n = 4) at six to seven substrate concentrations for triazolam, midazolam, and testosterone, and at two substrate concentrations for nifedipine. Analysis of multiple data points per liver sample based on a mixed competitive-noncompetitive model yielded mean inhibition constant K(i) values in the range of 0.011 to 0.045 µm. Ketoconazole IC50 increased at higher substrate concentrations, thereby excluding pure noncompetitive inhibition. For triazolam, testosterone, and midazolam α-hydroxylation, mean values of α (indicating the 'mix' of competitive and noncompetitive inhibition) ranged from 2.1 to 6.3. However, inhibition of midazolam 4-hydroxylation was consistent with a competitive process. Determination of K(i) and α based on the relation between 50% inhibitory concentration values and substrate concentration yielded similar values. Pre-incubation of ketoconazole with microsomes before addition of substrate did not enhance inhibition, whereas inhibition by troleandomycin was significantly enhanced by pre-incubation. Ketoconazole inhibition of triazolam α- and 4-hydroxylation, midazolam α-hydroxylation, testosterone 6β-hydroxylation, and nifedipine oxidation appeared to be a mixed competitive-noncompetitive process, with the noncompetitive component being dominant but not exclusive. Quantitative estimates of K(i) were in the low nanomolar range for all four substrates.

Tumor Necrosis Factor-α Mediates One Component of Competitive, Experience-Dependent Plasticity in Developing Visual Cortex

Rapid, experience-dependent plasticity in developing visual cortex is thought to be competitive. After monocular visual deprivation, the reduction in response of binocular neurons to one eye is matched by a corresponding increase to the other. Chronic optical imaging in mice deficient in TNFalpha reveals the normal initial loss of deprived-eye responses, but the subsequent increase in response to the open eye is absent. This mutation also blocks homeostatic synaptic scaling of mEPSCs in visual cortex in vitro, without affecting LTP. In monocular cortex, thought not to be subject to competition, responses in TNFalpha mutants are as reduced as in the binocular zone. Pharmacological inhibition of endogenous TNFalpha in wild-type mice phenocopies the knockout. These findings suggest that experience-dependent competition in developing visual cortex is the outcome of two distinct, noncompetitive processes, a loss of deprived-eye responses followed by an apparently homeostatic increase in responses dependent on TNFalpha signaling.

Importance of diversity. Reconciling natural selection and noncompetitive processes.

To better understand selection processes in evolutionary systems (ecological to economic to social to artificial systems), the origins and role of diversity are examined in two systems that show increased group functionality (better performance, efficiency, robustness, adaptability, stability, etc.). Diversity was chosen as a clarifying concept, because it appears to have been largely ignored, or misunderstood. One system is a model of group selection within an ecosystem. The other is the group solution of a sequential problem using self-organizing dynamics in the absence of any selection. A comparison of the two systems show that while diversity is essential to both, improvement by natural selection is derived from consuming diversity, whereas improvement by noncompetitive self-organization is decreased by any reduction in diversity. The resulting perspective is that natural selection is a mechanism that increases the functionality of the individual (or groups within a larger system); noncompetitive self-organization of the system, without need for selection, increases the functionality of the whole above that of the individual or group. The two extreme roles for diversity are reconciled if natural selection is not strongly expressed in these systems--"survival of the fittest" becomes "survival of the adequate"--so that noncompetitive processes can occur. The resulting view of a mature ecosystem is an elastic web of interactions in which natural selection is dormant or retains the status quo. The processes of natural selection for individual or group improvement are activated only if environment changes are sufficient to break the elastic interconnections, as might occur in punctuated equilibria.

When Would Educational Standards Help Improve Scholastic Achievement?

I study the potential effects on student performance to be expected from setting mandatory standards in primary and secondary education. To that end, I present a model in which investment in education is indivisible. Thus, if demand exceeds supply at any level of education, allocation is carried out--at least in part--via test scores. The model highlights how the effectiveness of educational standards in altering student performance depends on the college and secondary school education premia, the stringency of standards, and the supply of college education--factors which together determine the competitiveness of college admissions. A relatively high college education premium raises the incentive to finish high school and apply to college, but the marginal benefit of meeting standards or the cost of non-compliance depend on the secondary education premium. Thus, the effects on student performance if education standards are raised may be relatively small when the secondary education premium is relatively low. Moreover, when the supply of higher education is relatively abundant so that college entrance is a non-competitive process, students' incentive to make their best effort diminishes, and in that case, the role of education premia--and therefore of standards--as incentives may be limited.

When Would Educational Standards Help Improve Scholastic Achievement?

I study the potential effects on student performance to be expected from setting mandatory standards in primary and secondary education. To that end, I present a model in which investment in education is indivisible. Thus, if demand exceeds supply at any level of education, allocation is carried out--at least in part--via test scores. The model highlights how the effectiveness of educational standards in altering student performance depends on the college and secondary school education premia, the stringency of standards, and the supply of college education--factors which together determine the competitiveness of college admissions. A relatively high college education premium raises the incentive to finish high school and apply to college, but the marginal benefit of meeting standards or the cost of non-compliance depend on the secondary education premium. Thus, the effects on student performance if education standards are raised may be relatively small when the secondary education premium is relatively low. Moreover, when the supply of higher education is relatively abundant so that college entrance is a non-competitive process, students' incentive to make their best effort diminishes, and in that case, the role of education premia--and therefore of standards--as incentives may be limited.

Punctuated equilibrium: reconciling theory of revolutionary and incremental change

Using Simon's concept of nested hierarchies, this paper advances a new synthesis for understanding how and why the discontinuous change processes of punctuated equilibrium may occur in socio-economic settings. A key concept is the nested, multi-level organization of ‘deep structure’, the order in a system. This includes culture, technology, operating routines, control systems, organizational structure, resources and distributions of power. Using a modified evolutionary process, change is triggered when a disturbance disconfigures one or more levels of the system's deep structure. New variations of deep structure, constrained by more fundamental levels, emerge as deep structure reconfigures. The variations are sorted through competitive selection and other non-competitive processes. The variations are retained as part of the reconfigured deep structure. The concept of a nested, multi-level deep structure explains a continuum of change. Incremental change occurs when only the more marginal levels of deep structure are affected. Revolutionary change occurs when the fundamental levels of deep structure reconfigure, as do all more marginal levels nested within them. Copyright © 1999 John Wiley & Sons, Ltd.

Punctuated equilibrium: reconciling theory of revolutionary and incremental change

Using Simon's concept of nested hierarchies, this paper advances a new synthesis for understanding how and why the discontinuous change processes of punctuated equilibrium may occur in socio-economic settings. A key concept is the nested, multi-level organization of ‘deep structure’, the order in a system. This includes culture, technology, operating routines, control systems, organizational structure, resources and distributions of power. Using a modified evolutionary process, change is triggered when a disturbance disconfigures one or more levels of the system's deep structure. New variations of deep structure, constrained by more fundamental levels, emerge as deep structure reconfigures. The variations are sorted through competitive selection and other non-competitive processes. The variations are retained as part of the reconfigured deep structure. The concept of a nested, multi-level deep structure explains a continuum of change. Incremental change occurs when only the more marginal levels of deep structure are affected. Revolutionary change occurs when the fundamental levels of deep structure reconfigure, as do all more marginal levels nested within them. Copyright © 1999 John Wiley & Sons, Ltd.

A new peptide, 5-HT-moduline, isolated and purified from mammalian brain specifically interacts with [formula omitted] receptors

5-HT-Moduline (Leu-Ser-Ala-Leu) is a new endogenous peptide purified from rat brain which interacts specifically with 5- HT 1B 1D receptors. The binding interaction of 5-HT-Moduline with 5- HT 1B 1D receptors appeared to be a non-competitive process, since the B max value of [ 125I] cyanopindolol binding on rat brain cortical membranes was decreased without modification of the K d. This interaction was conserved on NIH 3T3 cells expressing the 5-HT 1 B receptor (IC 50 = 10 −11M) suggesting that the binding site for 5-HT-Moduline is localized on the 5-HT 1 B receptor protein. The observed interaction may lead to functional alterations of 5- HT 1B 1D receptors known to play an important role in regulating the release of 5-HT from serotonergic nerve terminals (autoreceptors) as well as the release of other neurotransmitters (heteroreceptors).

Characterization of Monoclonal Antibodies that Strongly Inhibit Electrophorus Electricus Acetylcholinesterase

In this study, we describe three different monoclonal antibodies (mAbs Elec-403, Elec-408, and Elec-410) directed against Electrophorus electricus acetylcholinesterase (AChE) which were selected as inhibitors for this enzyme. Two of these antibodies (Elec-403 and Elec-410), recognized overlapping but different epitopes, competed with snake venom toxin fasciculin for binding to the enzyme, and thus apparently recognized the peripheral site of AChE. In addition, the binding of Elec-403 was antagonized by 1,5-bis(4-allyldimethylammoniumphenyl)pentan-3-one dibromide (BW284C51) and propidium, indicating that the corresponding epitope encompassed the anionic site involved in the binding of these low-molecular-mass inhibitors. The third mAb (Elec-408), was clearly bound to another site on the AChE molecule, and its inhibitory effect was cumulative with those of Elec-403, Elec-410, and fasciculin. All mAbs bound AChE with high affinity and were as strong inhibitors with an apparent Ki value less than 0.1 nM. Elec-403 was particularly efficient with an inhibitory activity similar to that of fasciculin. Inhibition was observed with both charged (acetylthiocholine) and neutral substrates (o -nitrophenyl acetate) and had the characteristics of a non-competitive process. Elec-403 and Elec-410 probably exert their effect by triggering allosteric transitions from the peripheral site to the active site. The epitope recognized by mAb Elec-408 has not been localized, but it may correspond to a new regulatory site on AChE.

Characterization of Monoclonal Antibodies that Strongly Inhibit Electrophorus Electricus Acetylcholinesterase

In this study, we describe three different monoclonal antibodies (mAbs Elec-403, Elec-408, and Elec-410) directed against Electrophorus electricus acetylcholinesterase (AChE) which were selected as inhibitors for this enzyme. Two of these antibodies (Elec-403 and Elec-410), recognized overlapping but different epitopes, competed with snake venom toxin fasciculin for binding to the enzyme, and thus apparently recognized the peripheral site of AChE. In addition, the binding of Elec-403 was antagonized by 1,5-bis(4-allyldimethylammoniumphenyl)pentan-3-one dibromide (BW284C51) and propidium, indicating that the corresponding epitope encompassed the anionic site involved in the binding of these low-molecular-mass inhibitors. The third mAb (Elec-408), was clearly bound to another site on the AChE molecule, and its inhibitory effect was cumulative with those of Elec-403, Elec-410, and fasciculin. All mAbs bound AChE with high affinity and were as strong inhibitors with an apparent Ki values less than 0.1 nM. Elec-403 was particularly efficient with an inhibitory activity similar to that of fasciculin. Inhibition was observed with both charged (acetylthiocholine) and neutral substrates (o-nitrophenyl acetate) and had the characteristics of a non-competitive process. Elec-403 and Elec-410 probably exert their effect by triggering allosteric transitions from the peripheral site to the active site. The epitope recognized by mAb Elec-408 has not been localized, but it may correspond to a new regulatory site on AChE.

Ca 2+-sensitive monolayer electrodes

A Ca 2+ sensor based on the admittance change of synthetic membranes supported on derivatized silicon electrodes is reported. The ion-sensitive membranes consist of mixed monolayers of phospholipid and the Ca 2+-ligand ETH 1001. The electrodes are characterized electrochemically and their sensor performances are described. Through ion complexation by the neutral ligand, electrical charges are incorporated in the low-dielectric-constant environment of the sensitive layer. The number of charged complexes and thus the membrane admittance depend on the ion content of the electrolyte. The membrane response to Ca 2+ and the competitive binding of other cations are studied. A non-competitive process is observed if several ionophores, each one specific for a different ion, are incorporated in the membrane. Mixed layers with tetradecyl-18-crown-6 and ETH 1001 show both K + and Ca 2+ sensitivity. These electrodes allow direct comparison with a previously reported K + sensor based on tetradecyl-18-crown-6.

Paraquat Alters Growth, DNA and Protein Synthesis in Lung Epithelial Cell and Fibroblast Cultures

In vivo exposure to paraquat, a bipyridyl herbicide, is associated with selective necrosis of type I and type II alveolar pneumocytes. We examined the influence of paraquat on cell growth, DNA and protein synthesis in human and rat lung epithelial and fibroblast cell lines, to determine the effects and affinity of the chemical in vitro for cells of various origins. Cells were incubated with [3H]-thymidine or [3H]-proline in the absence or presence of 0.05–10mM paraquat for periods of 6 or 24 hours. Cell cultures grown in the presence of 50–200μM paraquat exhibited significantly lower cell numbers than comparable controls after 3 days. The suppression of DNA synthesis by paraquat was dose-dependent, but did not rely on the length of exposure. Paraquat inhibited protein synthesis and selectively decreased net production of low molecular weight proteins. NADPH levels were the same in both control and treated cultures. [14C]-Paraquat was accumulated during a 4-hour exposure period via an active non-competitive process. The results suggest that lung fibroblasts are as sensitive to the herbicide as epithelial cells. In addition, paraquat appears to interfere with transcription and/or translation by its ability to generate superoxide radicals, rather than by depletion of reducing equivalents.

Replacement events among tetrapods: expansion or competition?

Many macroevolutionary patterns have been explained in the past on the basis of expectations and prejudice rather than quantitative testing. Large-scale ecological replacements have been a prime example, where expectations of progress and competitive advantage have coloured interpretations. Equally, no doubt, others have looked for, and found, evidence for entirely noncompetitive processes to explain major replacements (reviewed, Benton 1987).A partially quantitative approach is presented, based on a study of tetrapod families, marine and nonmarine, through the interval from Devonian to the present day. New data bases of the history of tetrapod diversification have the advantage over older attempts of (1) a fully cladistic phylogeny, and hence monophyletic families; (2) a detailed overview of stratigraphy and improved range data; (3) palaeobiogeographic control; and, (4) definition of ecological categories in terms of mean body size categories, diet, main habitat types (fully marine; partially marine/ coastal; freshwater; aquatic/terrestrial; lowland; upland; arboreal, aerial).The bulk of the diversification of tetrapods is correlated with increases in the ranges both of habitats occupied and of diets (Benton 1990). However, tetrapod families came and went, and a large proportion of the diversification could have been driven by competition and progressive replacement of archaic families by competitively superior ones in ecological relays. In order to test this, the ranges of all tetrapod families were plotted against time and sorted into a variety of habitat, dietary, and palaeogeographic categories.The results do not support a generalised view of competitive ecological relays. The majority of families appear to have arisen within new cells of the matrix, and did not apparently overlap in time with, or follow closely after, any potential competitors. This would be the minimum requirement for a postulate of competition. Only some 5% of cases could be open to a competitive explanation, and these include certain well known examples, such as multituberculates/ rodents, plesiadapiforms/ rodents, ichthyosaurs/ mosasaurs. The present study has narrowed the odds againt large-scale competition as a significant motor of large-scale biotic replacements. Most new taxa of tetrapods appear to have arisen in response to the availability of empty adaptive space.Environmental shifts may also be detected during the course of tetrapod evolution, with expansions offshore to ever more fully aquatic lifestyles among marine tetrapods (because they all arose from terrestrial ancestors!), and with expansions from lowland tropical zones to temperate belts, uplands, and marginal lifestyles (burrowing, climbing, flying) among nonmarine tetrapods.

Dopamine inhibits Na(+)-H+ exchanger activity in renal BBMV by stimulation of adenylate cyclase

To determine a renal tubular mechanism for the natriuretic effect of dopamine (DA) and DA-1 agonists, we measured Na(+)-H+ exchange activity (amiloride sensitive) in rat renal cortical brush-border membrane vesicles (BBMV). Renal cortical tissues were preincubated with ligands before BBMV preparation to study Na(+)-H+ exchange activity in the absence of the added ligands that may compete for ion binding sites of the exchanger. DA and DA-1 agonist-inhibited Na(+)-H+ exchange activity was concentration and time dependent. The inhibitory effect was not due to increased permeability, collapse of the proton gradient, or change in vesicle size and did not extend to Na(+)-glucose symport. DA-2 agonists had no effect, whereas alpha-adrenergic agonists increased Na(+)-H+ exchange activity. Kinetic analysis revealed that the DA-1 agonist inhibited Na(+)-H+ exchange activity by a noncompetitive process. 2',5'-Dideoxyadenosine inhibited adenylate cyclase activity and reversed the inhibitory effect of DA-1 agonist on the exchanger. H4, an isoquinoline sulfonamide, which inhibits protein kinase A, also reversed the inhibitory effect of DA-1 agonist on the exchanger. Thus the DA-1 agonist-mediated inhibition of Na(+)-H+ exchange activity in BBMV is a receptor-mediated adenylate cyclase-linked process.