Rational redesign of neutral endopeptidase binding to merlin and moesin proteins

Neutral endopeptidase (NEP) is a 90‐ to 110‐kDa cell‐surface peptidase that is normally expressed by numerous tissues but whose expression is lost or reduced in a variety of malignancies. The anti‐tumorigenic function of NEP is mediated not only by its catalytic activity but also through direct protein–protein interactions of its cytosolic region with several binding partners, including Lyn kinase, PTEN, and ezrin/radixin/moesin (ERM) proteins. We have previously shown that mutation of the K¹⁹K²⁰K²¹ basic cluster in NEPs' cytosolic region to residues QNI disrupts binding to the ERM proteins. Here we show that the ERM‐related protein merlin (NF2) does not bind NEP or its cytosolic region. Using experimental data, threading, and sequence analysis, we predicted the involvement of moesin residues E¹⁵⁹Q¹⁶⁰ in binding to the NEP cytosolic domain. Mutation of these residues to NL (to mimic the corresponding N¹⁵⁹L¹⁶⁰ residues in the nonbinder merlin) disrupted moesin binding to NEP. Mutation of residues N¹⁵⁹L¹⁶⁰Y¹⁶¹K¹⁶²M¹⁶³ in merlin to the corresponding moesin residues resulted in NEP binding to merlin. This engineered NEP peptide–merlin interaction was diminished by the QNI mutation in NEP, supporting the role of the NEP basic cluster in binding. We thus identified the region of interaction between NEP and moesin, and engineered merlin into a NEP‐binding protein. These data form the basis for further exploration of the details of NEP‐ERM binding and function.     

Interspecific Competition and Niche Separation in Primates: A Global Analysis

Primates are an extraordinarily well-known tropical forest, mammalian taxon. We investigated potential modes of niche separation in primates by identifying sympatric species with putatively similar niche characteristics and assessing potential competition using data gleaned from an extensive literature review. We defined competing species-pairs as (a) sympatric species in which (b) the body mass of the larger species was within 30 percent of the smaller species' mass and (c) the species had the same category of diet. A sample of 43 well-studied forests (7–20 per continent) provided 673 pairs of sympatric primate species. Of these, 45 pairs (7%) are potential competitors by our definition. Africa has the largest number of competing pairs (17 pairs), while Asia might have the highest percentage of competitors in each forest site (17%). Niche separation was investigated for each pair by examining them for each of eight possible modes of separation: detailed differences in diets (28% of potential competitors), use of different heights in the forest (25%), use of different types of forest (14%), use of different locations within the forest (11%), use of support branches of different diameters (7%), different ranging behavior (6%), different techniques of prey capture (4%), and differential timing of activity (4%). The use of different heights in the forest is the dominant form of potential separation in Africa (31% of competing species-pairs) and Asia (38%), while detailed differences in diet appears to be the primary mode of niche separation in the Americas (26%) and Madagascar (32%).     

Effect of natural b-carotene supplementation in children exposed to radiation from the Chernobyl accident

Attempts were made to evaluate 709 children (324 boys and 385 girls) who had been exposed long-term to different doses of radiation during and after the Chernobyl accident and had moved to Israel between 1990 and 1994. Upon arrival, all of them underwent a check-up for most common clinical disorders and were then divided into three groups according to their residences (distance from the reactor) and the level of irradiation exposure: no radiation, <5 Ci/m², and >5 Ci/m², respectively. Blood serum analyses for total carotenoids, retinol, α-tocopherol and oxidized conjugated dienes in 262 of the children showed increased HPLC levels of conjugated dienes, indicating increased levels of oxidation of in vivo blood lipids in children from the contaminated areas. The levels were higher in girls than in boys. Some 57 boys and 42 girls were given a basal diet with a diurnal supplementation of 40 mg natural 9-cis and all-trans equal isomer mixture β-carotene in a capsulated powder form of the alga Dunaliella bardawil, for a period of 3 months. Blood serum analyses were regularly conducted before supplementation to determine the baseline effect of radiation exposure to the children, after 1 and 3 months of natural β-carotene supplementation. After supplementation, the levels of the oxidized conjugated dienes decreased in the children's sera without any significant changes in the level of total carotenoids, retinol or α-tocopherol. Other common blood biochemicals were within the normal range for all tests and no statistical differences before or after supplementation of β-carotene were noted. High pressure liquid chromatography (HPLC) analyses for carotenoids in the blood detected mainly oxycarotenoids, and to a lesser extent, all-trans β-carotene, α-carotene, but not 9-cis β-carotene. The results suggest that irradiation increases the susceptibility of lipids to oxidation in the Chernobyl children and that natural β-carotene may act as an in vivo lipophilic antioxidant or radioprotector. Received: 20 March 1998 / Accepted in revised form: 1 August 1998     

Microbiological,rheological and aromaticcharacteristics of fermented Uji (an East African Sour Porridge)

Three methods for fermentation of uji were compared in laboratory trials: spontaneous, backslopping (using an inoculum from a previous fermentation) and use of a starter culture of lactic acid bacteria. Spontaneous fermentation resulted in the slowest decrease in pH, while the use of starter culture led to the lowest final pH (3.5). Coliforms were eliminated in less than 8 h using backslopping or starter culture, but increased in numbers during spontaneous fermentation. The viscosity of uji was only marginally affected by the method of fermentation. The aroma profile following spontaneous fermentation contained esters with fruity notes and ethanol and higher alcohols, while mainly organic acids was produced by fermentation with the starter culture. Backslopping led to the lowest production of almost all volatiles identified.     

Successional theories

Succession is a fundamental concept in ecology because it indicates how species populations, communities, and ecosystems change over time on new substrate or after a disturbance. A mechanistic understanding of succession is needed to predict how ecosystems will respond to land-use change and to design effective ecosystem restoration strategies. Yet, despite a century of conceptual advances a comprehensive successional theory is lacking. Here we provide an overview of 19 successional theories (‘models’) and their key points, group them based on conceptual similarity, explain conceptual development in successional ideas and provide suggestions how to move forward. Four groups of models can be recognised. The first group (patch & plants) focuses on plants at the patch level and consists of three subgroups that originated in the early 20th century. One subgroup focuses on the processes (dispersal, establishment, and performance) that operate sequentially during succession. Another subgroup emphasises individualistic species responses during succession, and how this is driven by species traits. A last subgroup focuses on how vegetation structure and underlying demographic processes change during succession. A second group of models (ecosystems) provides a more holistic view of succession by considering the ecosystem, its biota, interactions, diversity, and ecosystem structure and processes. The third group (landscape) considers a larger spatial scale and includes the effect of the surrounding landscape matrix on succession as the distance to neighbouring vegetation patches determines the potential for seed dispersal, and the quality of the neighbouring patches determines the abundance and composition of seed sources and biotic dispersal vectors. A fourth group (socio-ecological systems) includes the human component by focusing on socio-ecological systems where management practices have long-lasting legacies on successional pathways and where regrowing vegetations deliver a range of ecosystem services to local and global stakeholders. The four groups of models differ in spatial scale (patch, landscape) or organisational level (plant species, ecosystem, socio-ecological system), increase in scale and scope, and reflect the increasingly broader perspective on succession over time. They coincide approximately with four periods that reflect the prevailing view of succession of that time, although all views still coexist. The four successional views are: succession of plants (from 1910 onwards) where succession was seen through the lens of species replacement; succession of communities and ecosystems (from 1965 onwards) when there was a more holistic view of succession; succession in landscapes (from 2000 onwards) when it was realised that the structure and composition of landscapes strongly impact successional pathways, and increased remote-sensing technology allowed for a better quantification of the landscape context; and succession with people (from 2015 onwards) when it was realised that people and societal drivers have strong effects on successional pathways, that ecosystem processes and services are important for human well-being, and that restoration is most successful when it is done by and for local people. Our review suggests that the hierarchical successional framework of Pickett is the best starting point to move forward as this framework already includes several factors, and because it is flexible, enabling application to different systems. The framework focuses mainly on species replacement and could be improved by focusing on succession occurring at different hierarchical scales (population, community, ecosystem, socio-ecological system), and by integrating it with more recent developments and other successional models: by considering different spatial scales (landscape, region), temporal scales (ecosystem processes occurring over centuries, and evolution), and by taking the effects of the surrounding landscape (landscape integrity and composition, the disperser community) and societal factors (previous and current land-use intensity) into account. Such a new, comprehensive framework could be tested using a combination of empirical research, experiments, process-based modelling and novel tools. Applying the framework to seres across broadscale environmental and disturbance gradients allows a better insight into what successional processes matter and under what conditions.     

New approaches to eliciting protective immunity through T cell repertoire manipulation: the concept of thymic vaccination

Conventional vaccines afford protection against infectious diseases by expanding existing pathogen-specific peripheral lymphocytes, both CD8 cytotoxic effector (CTL) and CD4 helper T cells. The latter induce B cell maturation and antibody production. As a consequence, lymphocytes within the memory pool are poised to rapidly proliferate at the time of a subsequent infection. The "thymic vaccination" concept offers a novel way to alter the primary T cell repertoire through exposure of thymocytes to altered peptide ligands (APL) with reduced T cell receptor (TCR) affinity relative to cognate antigens recognized by those same TCRs. Thymocyte maturation (i.e. positive selection) is enhanced by low affinity interaction between a TCR and an MHC-bound peptide in the thymus and subsequent emigration of mature cells into the peripheral T lymphocyte pool follows. In principal, such variants of antigens derived from infectious agents could be utilized for peptide-driven maturation of thymocytes bearing pathogen-specific TCRs. To test this idea, APLs of gp33-41, a Db-restricted peptide derived from the lymphocytic choriomeningitis virus (LCMV) glycoprotein, and of VSV8, a Kb-restricted peptide from the vesicular stomatitis virus (VSV) nucleoprotein, have been designed and their influence on thymic maturation of specific TCR-bearing transgenic thymocytes examined in vivo using irradiation chimeras. Injection of APL resulted in positive selection of CD8 T cells expressing the relevant viral specificity and in the export of those virus-specific CTL to lymph nodes without inducing T cell proliferation. Thus, exogenous APL administration offers the potential of expanding repertoires in vivo in a manner useful to the organism. To efficiently peripheralize antigen-specific T cells, concomitant enhancement of mechanisms promoting thymocyte migration appears to be required. This commentary describes the rationale for thymic vaccination and addresses the potential prophylactic and therapeutic applications of this approach for treatment of infectious diseases and cancer. Thymic vaccination-induced peptide-specific T cells might generate effective immune protection against disease-causing agents, including those for which no effective natural protection exists.     

Religious visibility: perceptions and experiences of residents in two Muslim concentration suburbs in Melbourne,Australia

In recent decades, and especially after the 9/11/2001 terrorist attack on US, an antipathy towards and fear of Muslim minorities in Western countries have increased, forming part of the current widespread anti-immigration sentiment. In this context, the ‘religiously visible’ Muslims are the most obvious target of negative perceptions, discrimination and other manifestations of ‘Islamophobia’. This paper uses quantitative and qualitative data on religious visibility collected through a survey and in-depth interviews in two suburbs with residential concentrations of Muslims in Melbourne, Australia. The two localities, ‘Broadburb’ and ‘Greenburb’, have similar proportions of Muslim residents (about 1/3) but the levels of religious visibility differ. The paper discusses perceptions and experiences of being religiously visible in a secular society, and particularly being a ‘visible Muslim’. We also discuss perceptions of Muslim visibility by others – non-visible Muslims and non-Muslims – who share neighbourhoods with the visible Muslim minority.