Statistical fluctuations in population bargaining in the ultimatum game: Static and evolutionary aspects

We explore the emergent behavior in heterogeneous populations where players negotiate via an ultimatum game: two players are offered a gift, one of them (the proposer) suggests how to divide the offer while the other player (the responder) can either accept or reject the deal. Rejection is detrimental to both players as it results in no earnings. In this context, our contribution is twofold: (i) we consider a population where the distribution of used strategies is constant over time and properties of the random payoff received by the players (average and higher moments) are reported from simple exact methods and corroborated by computer simulations; (ii) the evolution of a population is analyzed via Monte Carlo simulations where agents may change independently the proposing and accepting parameters of their strategy depending on received payoffs. Our results show that evolution leads to a stationary state in which wealth (accumulated payoff) is fairly distributed. As time evolves, an increase in average payoff and a simultaneous variance decrease is observed when we use a dynamics based on a probabilistic version of the saying: “One should not comply with small earnings, but one's greed must be limited.”     

Conserving the Himalayan forests: approaches and implications of different conservation regimes

The conservation of Himalayan forests is big concern in view of global agenda. Many studies in this endeavor reported that the rate of forests degradation is posing a severe threat to the landscape and existing biodiversity in the Himalayas. Currently there many conservation approaches exists and of them four are widely recognized (1) Conservation through traditional religious beliefs “traditional conserved forests” (TCF); (2) Conservation through governmental planning and schemes “government conserved forests” (GCF); (3) Conservation through creation of protected areas (PAF); and (4) Conservation through community efforts “community conserved forests” (CCF). Our hypothesis in this direction says that all the conservation approaches lead to same results concerning to forest conservation. To testify our hypothesis we have studied the forests of each conservation regimes and evaluated them based on the identified indicators. We have done empirical studies and following the cloud-free satellite data were used for last three decades (such as Multi-Spectral Scanner, Linear Imaging and Self Scanning, and Enhanced Thematic Mapper ) to study a change in vegetation dynamics of the mountain forests in multi-temporal dimension. Our research concluded that community conservation approach have greater significance for biodiversity conservation and management in the Himalayan region. Here we support the model of CCF for forest ecosystem conservation, alongside the sustainable livelihood of the mountain societies. But every conservation regimes has its own importance in viewpoint of the particular objectives. Therefore, we suggests advancement and revision of PAF and GCF however, some elements of CCF can be introduced in TCF for making up it more sound in view of rapid socio-economic and cultural changes taking place in the communities. An erratum to this article can be found at     

Liver integrity after warm ischemia in situ and brief preservation ex vivo: the value of aerobic post-conditioning

We evaluated the respective effects of warm ischemic injury in non-heart-beating donor (NHBD) grafts and/or cold ischemia time on liver viability. Eventually, the restorative potential of oxygenated hypothermic perfusion after cold storage should be investigated. Livers were retrieved from male Wistar rats and preserved with HTK-solution for 6 h or 18 h by cold storage (CS). Organ retrieval took place either prior to (ctrl.) or 30 min after cardiac arrest (NHBD). Compared to 6 h CS of ctrl. livers, enzyme leakage and functional recovery (oxygen consumption, ammonia clearance, bile production) upon warm reperfusion were massively deteriorated after 18 h CS in NHBD-livers. By contrast, 6 h CS of NHBD resulted in an only limited impairment of all parameters, which was found quite similar to the results in ctrl. after 18 h CS. Induction of cellular apoptosis (cleavage PARP) was found equally influenced by preceding warm ischemia (NHBD) or extended times of CS, but significantly triggered only by the combination of both events. After 6 h of CS, 1 h of oxygenated hypothermic machine perfusion (‘post-conditioning’) was able to bring the performance of NHBD-liver into line with the controls. Based on this work, we concluded that a limited time of warm ischemia in the donor only multiplied graft injury after long-term CS, but does not need to preclude acceptable results if reperfusion is initiated after short periods of CS. Moreover, conditioning of those grafts is effective even 1 h prior to implantation and may help to judge liver viability according to adequate parameters after hypothermic machine perfusion has been established.     

Comparative phylogeography of two sibling species of forest‐dwelling rodent (Praomys rostratus and P. tullbergi) in West Africa: different reactions to past forest fragmentation

Two sibling species of the rodent genus Praomys occur in West African forests: P. tullbergi and P. rostratus. By sampling across their geographical ranges (459 individuals from 77 localities), we test the hypothesis that climatic oscillations during the Quaternary made an impact on the observed pattern of cytochrome b sequence variation. We show that, although these two species have parapatric geographical distributions, their phylogeographical histories are dissimilar, which could be related to their distinct ecological requirements. Since the arid phases of the Pleistocene were characterized by isolated forest patches, and intervening wetter periods by forest expansion, these changes in forest cover may be the common mechanism responsible for the observed phylogeographical patterns in both of these species. For example, in both species, most clades had either allopatric or parapatric geographical distributions; however, genetic diversity was much lower in P. tullbergi than in P. rostratus. The genetic pattern of P. tullbergi fits the refuge hypothesis, indicating that a very small number of populations survived in distinct forest blocks during the arid phases, then expanded again with forest recovery. In contrast, a number of populations of P. rostratus appear to have survived during the dry periods in more fragmented forest habitats, with varying levels of gene flow between these patches depending on climatic conditions and forest extent. In addition, historical variations of the West African hydrographic network could also have contributed to the pattern of genetic differentiation observed in both species.     

The ethylene action in the development of cellular slime molds: an analogy to higher plants

Summary The cellular slime moldDictyostelium mucoroides-7 (Dm 7) and its mutant (MF 1) exhibit sexual or asexual development depending upon culture conditions. During the sexual cycle macrocyst formation occurs, whereas sorocarps containing spores and stalk cells are asexually formed. As previously reported, the macrocyst formation is marked by the emergence of true zygotes, and is induced by a potent plant hormone, ethylene. The concentration of ethylene required for macrocyst induction was determined to establish the similarity of ethylene action between this organism and higher plants. Macrocysts are induced by low (1 l/l) exogenous concentrations of ethylene. Higher concentrations (10–1,000 ul/l) also gave essentially the same inductive activity. Ethionine, an analogue of methionine, was found to inhibit zygote formation during sexual development through its interference with ethylene production by Dm 7 and MF 1 cells. In fact, the inhibitory effect of ethionine was mostly nullified by the application of ethylene, S-adenosyl-L-methionine, or 1-aminocyclopropane-1-carboxylic acid. Taken together these results suggest that both the effective concentration of ethylene and the pathway of ethylene biosynthesis inD. mucoroides may be similar to those in higher plants. Ethylene was also found to be produced in various species and strains of cellular slime molds, even during the asexual process. The possible functions of ethylene in the asexual development are discussed in relation to cell aggregation and differentiation.Abbreviations SAM S-adenosyl-L-methionine - ACC 1-aminocyclopropane-1-carboxylic acid - AOA (aminooxy) acetic acid - BSS Bonner's salt solution - DAPI 4,6-diamidino-2-phenylindole     

Cytotoxicity, intracellular distribution and uptake of doxorubicin and doxorubicin coupled to cell-penetrating peptides in different cell lines: A comparative study

One of the major obstacles which are opposed to the success of anticancer treatment is the cell resistance that generally develops after administration of commonly used drugs. In this study, we try to overcome the tumour cell resistance of doxorubicin (Dox) by developing a cell-penetrating peptide (CPP)-anticancer drug conjugate in aim to enhance its intracellular delivery and that its therapeutic effects. For this purpose, two cell-penetrating peptides, penetratin (pene) and tat, derived from the HIV-1 TAT protein, were chemically conjugated to Dox. The cytotoxicity, intracellular distribution and uptake were accessed in CHO cells (Chinese Hamster Ovarian carcinoma cells), HUVEC (Human Umbilical Vein Endothelial Cells), differentiated NG108.15 neuronal cell and breast cancer cells MCF7drug-sensitive or MDA-MB 231 drug-resistant cell lines. The conjugates showed different cell killing activity and intracellular distribution pattern by comparison to Dox as assessed respectively by MTT-based colorimetric cellular cytotoxicity assay, confocal fluorescence microscopy and FACS analysis. After treatment with 3 μM with Dox-CPPs for 2 h, pene increase the Dox cytotoxicity by 7.19-fold in CHO cells, by 11.53-fold in HUVEC cells and by 4.87-fold in MDA-MB 231 cells. However, cytotoxicity was decreased in NG108.15 cells and MCF7. Our CPPs-Dox conjugate proves the validity of CPPs for the cytoplasmic delivery of therapeutically useful molecules and also a valuable strategy to overcome drug resistance.     

幼虫期短时高温暴露对二点委夜蛾存活和繁殖的影响

【目的】随着全球气候变暖,夏季短时极端高温发生的频率逐渐增加。本研究旨在探明二点委夜蛾Athetis lepigone幼虫期对高温的适应性。【方法】将二点委夜蛾不同日龄(1,6,12和18日龄)幼虫在不同高温(35,38和41℃)条件下暴露不同时间(0.5,1,2,4和6 h)后转移至适温(26℃)继续饲养,观察短时高温对其存活率、发育历期、化蛹率、羽化率、雌虫寿命、单雌产卵量及次代卵孵化率的影响。【结果】幼虫期短时高温暴露的温度和时间对二点委夜蛾幼虫的存活率和发育历期有显著影响,而对化蛹率、成虫羽化率、雌虫寿命、单雌产卵量以及次代卵孵化率影响不显著。随着温度的升高和处理时间的延长,幼虫存活率逐渐降低,发育历期逐渐延长。其中,18日龄的幼虫最为敏感,38℃和41℃暴露6 h后存活率分别为58.3%和17.7%,显著低于对照,发育历期分别为25.5 d和29.2 d,较对照显著延长。【结论】幼虫期经历短时高温暴露仅对幼虫的存活和发育历期有影响,而对后续蛹和成虫的生长发育及成虫繁殖力没有影响。     

Classification of hospital pathways in the management of cancer: Application to lung cancer in the region of burgundy

Context: The evaluation of national cancer plans is an important aspect of their implementation. For this evaluation, the principal actors in the field (doctors, nurses, etc.) as well as decision-makers must have access to information that is reliable, synthetic and easy to interpret, and which reflects the implementation process in the field. We propose here a methodology to make this type of information available in the context of reducing inequalities with regard to access to healthcare for patients with lung cancer in the region of Burgundy. Methods: We used the national medico-administrative DRG-type database, which gathers together all hospital stays. By using this database, it was possible to identify and reconstruct the care management history of these patients. That is, by linking together all attended hospitals, sorted chronologically. Eligible patients were at least 18 years old, whatever the gender and had undergone surgery for their lung cancer. They had to be residents of Burgundy at the time of the first operation between 2006 and 2008. Patient's pathway was defined as the sequence of all attended hospitals (hospital stays) during the year of follow up linked together using an anonymised patient identifier. We then constructed a pathway typology of pathway using an unsupervised clustering method, and conducted a spatial analysis of this typology. Results: Between 2006 and 2008, we selected 495 patients in the 4 administrative departments of the Burgundy region. They accounted for a total of 3821 stays during the year of follow-up. There were 393 men (79%) and the mean age was 64 (95% confidence interval: 63–65) years. We reconstructed 94 pathways (about five per patient). Here, neighbourhood's cares accounted for 41% of them, while 44% included a surgical intervention outside the region of Burgundy. We constructed a pathway typology with five classes. Spatial analysis showed that the vast majority of initial surgeries took place in the major regional centres. Conclusion: The construction of a pathway typology leads to better understanding of the reasoning that lies behind the movements of patients. It opens the way for analysis of the collaboration between the different healthcares establishments attended, which should bring to light associations that need to be developed.     

At the core of survival: autophagy delays the onset of both apoptotic and necrotic cell death in a model of ischemic cell injury

Ischemic cell injury leads to cell death. Three main morphologies have been described: apoptosis, cell death with autophagy and necrosis. Their inherent dynamic nature, a point of no return (PONR) and molecular overlap have been stressed. The relationship between a defined cell death type and the severity of injury remains unclear. The functional role of autophagy and its effects on cell death onset is largely unknown. In this study we report a differential induction of cell death, which is dependent on the severity and duration of an ischemic insult. We show that mild ischemia leads to the induction of autophagy and apoptosis, while moderate or severe ischemia induces both apoptotic and necrotic cell death without increased autophagy. The autophagic response during mild injury was associated with an ATP surge. Real-time imaging and Fluorescence Resonance Energy Transfer (FRET) revealed that increased autophagy delays the PONR of both apoptosis and necrosis significantly. Blocking autophagy shifted PONR to an earlier point in time. Our results suggest that autophagic activity directly alters intracellular metabolic parameters, responsible for maintaining mitochondrial membrane potential and cellular membrane integrity. A similar treatment also improved functional recovery in the perfused rat heart. Taken together, we demonstrate a novel finding: autophagy is implicated only in mild injury and positions the PONR in cell death.     

The pitfalls of extrapolation in conservation: movements and habitat use of a threatened toad are different in the boreal forest

Widely distributed species often vary geographically in their ecology. Thus, results of studies done in one part of their range cannot necessarily be extrapolated readily to populations elsewhere. This problem is particularly important for threatened species whose ecology has been studied in a few disconnected locations. The Canadian toad Bufo ( Anaxyrus ) hemiophrys occupies a large geographic range in western North America, but most studies of its ecology have been done in the prairies, where the species is considered to be closely associated with aquatic habitats. However, B. hemiophrys also occurs in boreal forest, where it faces threats from logging activities, especially if it uses upland habitats far from ponds and lakes. We radio-tracked 29 toads in the boreal forest of northern Alberta, Canada to determine their patterns of movement and habitat use. Most movements between fixes were <50 m, but toads sometimes made longer movements exceeding 100 m. Over time, however, these short-term movements combined into large-scale directional movements that were highly variable among toads in both tortuosity and timing, but which generally took toads into upland forested habitats. Putative hibernacula also were located in upland sites. However, despite this terrestriality, toads still were associated with wetlands, using them significantly more often than would be expected based on their proportionate areal contribution to the landscape. Nonetheless, use of upland sites and long-distance terrestrial movements differentiate this population of B. hemiophrys from those studied in prairie environments. Conservation plans based on what we know about the species elsewhere therefore would be inappropriate in this region. Management often requires site-specific information, which can be obtained only from natural-history studies of the populations in question.     

Studies on the susceptibility of different culture morphotypes of Listeria monocytogenes to uptake and survival in human polymorphonuclear leukocytes

This study demonstrated that atypical virulent filaments of Listeria monocytogenes (rough variant type II and designated FR for this study), isolated from clinical specimens or generated during exposure to pulsed-plasma gas discharge in liquids, were shown to be capable of survival when engulfed by human polymorphonuclear leukocytes (PMNLs). Factors shown to significantly influence the maximal respiratory burst response in PMNLs and survival of different internalized cell or filament forms of L. monocytogenes were bacterial strain, culture form, degree of opsonization (with and without the use of 10% serum) and composition of the bacterial growth media used before uptake by PMNLs. Opsonized regular-sized L. monocytogenes cells grown on blood agar (BA) elicited the greatest respiratory burst response and survived best in PMNLs. The filamentous (FR) and multiple cell chain (MCR) rough variants were significantly less susceptible to uptake and survival in PMNLs. Supplementation of tryptone soya agar with hemin resulted in significantly reduced chemiluminescence responses in phagocytosing PMNLs compared with the maximal levels observed from prior bacterial growth on BA or brain heart infusion agar that also contained a source of iron. The MCR variants secreting decreased levels of a peptidoglycan hydrolase CwhA protein exhibited the lowest percentage survival when internalized in PMNLs compared with wild-type smooth or FR culture variants as determined by the macrophage-killing assay.     

Graph-theoretical assignment of secondary structure in multidimensional protein NMR spectra: Application to the lac repressor headpiece

Summary A novel procedure is presented for the automatic identification of secondary structures in proteins from their corresponding NOE data. The method uses a branch of mathematics known as graph theory to identify prescribed NOE connectivity patterns characteristic of the regular secondary structures. Resonance assignment is achieved by connecting these patterns of secondary structure together, thereby matching the connected spin systems to specific segments of the protein sequence. The method known as SERENDIPITY refers to a set of routines developed in a modular fashion, where each program has one or several well-defined tasks. NOE templates for several secondary structure motifs have been developed and the method has been successfully applied to data obtained from NOESY-type spectra. The present report describes the application of the SERENDIPITY protocol to a 3D NOESY-HMQC spectrum of the ¹⁵N-labelled lac repressor headpiece protein. The application demonstrates that, under favourable conditions, fully automated identification of secondary structures and semi-automated assignment are feasible.Abbreviations 2D, 3D two-, three-dimensional - NOESY nuclear Overhauser enhancement spectroscopy - HMQC heteronuclear multiple quantum coherence - SSE secondary structure element - SERENDIPITY SEcondary structuRE ideNtification in multiDImensional ProteIn specTra analYsis Supplementary Material available from the authors: Two tables containing the total number of mappings resulting from the graph search procedure for simulated and experimental NOE data.     

Non-timber forest product harvesting in alien-dominated forests: effects of frond-harvest and rainfall on the demography of two native Hawaiian ferns

Non-timber forest products (NTFP) represent culturally and economically important resources for millions of people worldwide. Although many NTFP are harvested from disturbed habitats and therefore subject to multiple pressures, few quantitative studies have addressed this issue. Similarly few NTFP studies have assessed seasonal variation in demographic rates even though this can confound harvest effects. In Hawaiȁ8i, the wild-gathered ferns, Microlepia strigosa and Sphenomeris chinensis, represent highly important cultural resources but declining populations have led to conservation concerns. Both ferns are harvested from disturbed, alien-dominated forests and contemporary Hawaiian gathering practices often consist of harvest and concurrent weeding of alien invasive species. We assessed the effects of concurrent frond-harvest and alien species weeding on frond structure, density, and rates of production by comparing experimentally harvested vs. control plots, and documented relationships between frond demographic patterns and precipitation. Gathering practices had no impact on frond density of either species or on most other demographic parameters over the short term. Exceptions included a significant decrease in the density of the longest S. chinensis fronds and a significant decrease in M. strigosa frond production when fronds were gathered without alien weeding. However, seasonal and annual changes in frond density and production occurred across all plots of both species and were significantly correlated with precipitation. The relatively low harvest effects for both species are likely due to several factors including short frond longevity and the strict criteria used by gatherers to select harvestable fronds. The potential for sustainable harvest in the context of alien-dominated forests is discussed.     

From computational modelling of the intrinsic apoptosis pathway to a systems-based analysis of chemotherapy resistance: achievements,perspectives and challenges in systems medicine

Our understanding of the mitochondrial or intrinsic apoptosis pathway and its role in chemotherapy resistance has increased significantly in recent years by a combination of experimental studies and mathematical modelling. This combined approach enhanced the quantitative and kinetic understanding of apoptosis signal transduction, but also provided new insights that systems-emanating functions (i.e., functions that cannot be attributed to individual network components but that are instead established by multi-component interplay) are crucial determinants of cell fate decisions. Among these features are molecular thresholds, cooperative protein functions, feedback loops and functional redundancies that provide systems robustness, and signalling topologies that allow ultrasensitivity or switch-like responses. The successful development of kinetic systems models that recapitulate biological signal transduction observed in living cells have now led to the first translational studies, which have exploited and validated such models in a clinical context. Bottom-up strategies that use pathway models in combination with higher-level modelling at the tissue, organ and whole body-level therefore carry great potential to eventually deliver a new generation of systems-based diagnostic tools that may contribute to the development of personalised and predictive medicine approaches. Here we review major achievements in the systems biology of intrinsic apoptosis signalling, discuss challenges for further model development, perspectives for higher-level integration of apoptosis models and finally discuss requirements for the development of systems medical solutions in the coming years.     

The cultivation bias: different communities of arbuscular mycorrhizal fungi detected in roots from the field,from bait plants transplanted to the field,and from a greenhouse trap experiment

The community composition of arbuscular mycorrhizal fungi (AMF) was investigated in roots of four different plant species (Inula salicina, Medicago sativa, Origanum vulgare, and Bromus erectus) sampled in (1) a plant species-rich calcareous grassland, (2) a bait plant bioassay conducted directly in that grassland, and (3) a greenhouse trap experiment using soil and a transplanted whole plant from that grassland as inoculum. Roots were analyzed by AMF-specific nested polymerase chain reaction, restriction fragment length polymorphism screening, and sequence analyses of rDNA small subunit and internal transcribed spacer regions. The AMF sequences were analyzed phylogenetically and used to define monophyletic phylotypes. Overall, 16 phylotypes from several lineages of AMF were detected. The community composition was strongly influenced by the experimental approach, with additional influence of cultivation duration, substrate, and host plant species in some experiments. Some fungal phylotypes, e.g., GLOM-A3 (Glomus mosseae) and several members of Glomus group B, appeared predominantly in the greenhouse experiment or in bait plants. Thus, these phylotypes can be considered r strategists, rapidly colonizing uncolonized ruderal habitats in early successional stages of the fungal community. In the greenhouse experiment, for instance, G. mosseae was abundant after 3 months, but could not be detected anymore after 10 months. In contrast, other phylotypes as GLOM-A17 (G. badium) and GLOM-A16 were detected almost exclusively in roots sampled from plants naturally growing in the grassland or from bait plants exposed in the field, indicating that they preferentially occur in late successional stages of fungal communities and thus represent the K strategy. The only phylotype found with high frequency in all three experimental approaches was GLOM A-1 (G. intraradices), which is known to be a generalist. These results indicate that, in greenhouse trap experiments, it is difficult to establish a root-colonizing AMF community reflecting the diversity of these fungi in the field roots because fungal succession in such artificial systems may bias the results. However, the field bait plant approach might be a convenient way to study the influence of different environmental factors on AMF community composition directly under the field conditions. For a better understanding of the dynamics of AMF communities, it will be necessary to classify AMF phylotypes and species according to their life history strategies.     

Application of the continuous variation method to cooperative interactions: mechanism of Fe(II)-ferrozine chelation and conditions leading to anomalous binding ratios

The method of continuous variation, often known as the Job plot, has long been used for determining the stoichiometry of two interacting components. The correct binding ratio, n, is generally obtained when the total concentration of the reactants, C_o, is much greater than the dissociation constants involved. For non-cooperative binding systems, the stoichiometry varies between one and n as C_o increases; whereas for positive cooperative systems, values larger than n may be observed at low C_o. In this report, we present examples to illustrate how the changing apparent stoichiometries as a function of C_o can provide clues for differentiating various binding mechanisms. To test these concepts, we examined the chelation of Fe(II) with ferrozine in the range of C_o=7 to 210 μM with Fe(II) expressed in molar concentration or in terms of its binding equivalents (three in this case). The results were analyzed according to several models and found to be most consistent with the mechanism of one-step complex formation or infinite cooperativity with a K_d of 8 μM.     

New Screening Method for the Rapid Identification of Blocked Mutants and Their Products: Application to Erythromycin and Oleandomycin Producing Strains

γ-Glutamyltransferase from fruiting bodies of Lentinus edodes was further tested for its activation by chaotropic ions such as SCN^?, NO₃^?, Cl^?, Br^?, I^?, F^? and C1O₄^?. The thiocyanate ion increased the Km value for γ-glutamyl-p-nitroanilide without affecting the V_max value of the reaction, whereas other anions as represented by NO₃^? and Br^? increased the V_max without affecting the Km. Jhe inactivation of the enzyme by the SH group-orienting reagents, iodoacetamide and hydrogen peroxide, was stimulated by SCN^? but not by the other anions.

The activator anions protected the enzyme against its inactivation by chemical modification with 2,3-butanedione in borate. Their efficiency was parallel to the activator potency of the respective anions, except for SCN^? which provided less protection than expected from its activation potency. These dissociable effects of activator anions might be explained by two different mechanisms; binding of SCN^? to a basic group to bring about a significant change in protein conformation and binding of other anions by electrostatic and hydrophobic forces to an arginyl residue located near the active site of the enzyme.