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Response Mechanisms (response + mechanism)
Kinds of Response Mechanisms Selected AbstractsSkills under threat: the case of HIV/AIDS in the mining industry in ZimbabweJOURNAL OF INTERNATIONAL DEVELOPMENT, Issue 5 2006Caroline N. Matangi Abstract The Zimbabwe mining industry is currently battling to arrest further spread of the HIV/AIDS crisis in workplaces, especially its impact on labour productivity. Labour in the closed community of mines has been greatly susceptible to HIV/AIDS infection. The current AIDS incidence in the mine sites is estimated at a weighted average of 15,per,cent amongst miners, with the largest category of workers,the 30,39 years age group,also constituting the worst affected category. Given the current state of the country's economy and consequently its adverse impact on the lifestyle of miners, the pandemic is expected to increase. This paper builds on the work of the ILO (1995) involving a survey of 18 various firms/institutions. The survey was carried out in Zambia in order to assess the impact of HIV/AIDS on the productive labour force. The survey revealed that many of the firms are experiencing irregular work attendance, ,wasted' training as some of the trained workers are constantly ill or die, high medical bills, funeral costs and reduced productivity and profits. An analysis of data on the main causes of death in 1993 shows that at least 61.8,per,cent of deaths could be attributed to causes that are very closely related to HIV/AIDS complications. Based on points highlighted by respondents and analysis of symptoms suffered, it was observed that HIV/AIDS tended to affect most general workers (36.8,per,cent), followed by the lower management (30.9,per,cent) and the middle management (20.6,per,cent). Comparatively, 11.8,per,cent of the deaths in 1993 belonged to the top management. Although it is hard to appreciate the meaning of the figures without knowledge of the number of people in each category, it nevertheless helps to form a clear picture of the impact of HIV/AIDS on industry. This paper seeks to further investigate the impact of HIV/AIDS on the productive labour force, by focusing on one particular industry,mining,using a blend of research methods to collect the data. This paper examines the impact of HIV/AIDS on the productive labour force and management responses. It forms part of the findings of data gathered in 2001 in the mining industry in Zimbabwe, to examine factors affecting management responses to HIV/AIDS in the mine sites. Zimbabwe is a country with a complex historical legacy of mine labour. This phenomenon can largely be attributed to the production oriented nature of the mining industry. Mines focus mainly on mineral extraction and as a result the bulk of mine workers tend to be production workers whose skills have developed over long periods of time. Production workers on mines have a tradition of long-term employment. This phenomenon has meant that labour in the mines is hard to replace as a result of skills, especially tacit knowledge, acquired over many years. Thus while the recent closure of some gold mines, largely due to low commodity prices, has meant that more miners are available in the labour market, this situation has not necessarily eased the process of replacing labour lost to the HIV/AIDS epidemic, as certain skills are firm specific. Production workers are predominantly male with the bulk falling in the 35,39 years age group. Most mine workers reside in mine villages, a colonial legacy that ensured miners were close to the workplace. The village system is a system of housing labourers, which demonstrates capitalistic methods of controlling labour and minimising costs. Of significance in this study's background is how the village system has come to be viewed as a factor in the spread of HIV/AIDS in the mining communities, because of its ,closed' nature. It is against this complex historical backdrop that the paper turns to examine the impact of the HIV/AIDS pandemic on production workers and management responses to the crisis using the Resource Based View of the Firm model (RBV), one of the theories in the Strategic Human Resource Management (SHRM) tradition. RBV was chosen for this study out of many HRM models that exist, because this theory, in particular, explains why it is advantageous for sites to use their ,unique' firm based resources in order to achieve sustainable competitive advantage. Given this rationale it was, therefore, presumed that this theory would best apply in mines battling with the adverse impact of HIV/AIDS on productivity, especially in the light of the harsh national economic climate, which would likely place limitations on response mechanisms. Further, the issue of firm-specific skills was also taken into consideration as an important factor in the mines, limiting their ability to resort to external solutions. Thus, given these factors, RBV was deemed the most appropriate model. The study finds that the pandemic depresses labour productivity through a number of significant ways: increased rate of HIV/AIDS induced absenteeism gradual labour turnover as a result of AIDS induced morbidity; and consequently declining skills availability, particularly firm-specific skills. Maintaining labour productivity in the face of gradually diminishing skills and indisposed labour will be key to softening the adverse economic consequences of the pandemic in the mines. To reduce the threat to labour productivity, mines must find ways of utilising, to the maximum extent practicable, existing skills. Results indicate that a move towards the utilisation of existing miners is the most favoured response mechanism in most mines. Utilising existing miners enables mines from spending financial resources on avoidable recruitment and training and quite often mechanisation, which may not necessarily be compatible with the old infrastructure in certain mines. Copyright © 2006 John Wiley & Sons, Ltd. [source] Effects of phosphate supply and elevated CO2 on root acid phosphatase activity in Pinus densiflora seedlingsJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 2 2006Mariko Norisada Abstract The exudation of root acid phosphatase (APase) is a plant response mechanism to phosphorus (P) deficiency. Under conditions of elevated CO2, P demand increases and possibly further enhances APase activity. We examined the activity of APase in 1-year-old ectomycorrhizal Pinus densiflora Sieb. et Zucc. seedlings grown in potted sand in the greenhouse under ambient (400 ,mol mol,1) and elevated (700 ,mol mol,1) CO2 with three modes of P supply: inorganic (NaH2PO4; Pin), organic (inositol hexaphosphate dodecasodium salt; Porg), and no phosphate (P0) for 78 d. Phosphorus limitations decreased P content in leaves and roots with lowest P content in P0 treatments, irrespective of CO2 conditions. However, P limitations decreased plant biomass at elevated CO2 levels, but not at ambient CO2 levels. The content in leaves of nutrients other than P was mostly unaffected by P supply, but decreased under elevated CO2. This observation was attributed to starch accumulation in leaves at elevated CO2, especially in the P0 treatment. The photosynthetic activity (expressed per unit of chlorophyll) was unaffected by P supply, but tended to be less at elevated CO2. There was no increase in root APase activity of Pinus densifolia in response to the P shortage caused by elevated CO2. [source] Fast cars, fast food, and fast fixes: industry responses to current ethical dilemmas for Australian advertisersJOURNAL OF PUBLIC AFFAIRS, Issue 2 2007Sandra C. Jones This paper reviews three ethical dilemmas currently facing advertisers for cars, fast food and pharmaceuticals in the U.S., U.K. and Australia, and discusses Australian industry responses to these dilemmas. In Australia, as in the U.S. and U.K., the main response mechanism for advertisers has been the introduction of self-regulatory codes of practice. It is important to note that in a number of cases there is no conclusive evidence of the argued harm from advertising that is subsequently banned or regulated. A review of the general and trade press, and the records of the Australian Advertising Standards Board, finds that industry responses tend to be based on industry rather than community concerns, with the primary motive being to avoid deleterious outcomes for the industry rather than for society as a whole. Copyright © 2007 John Wiley & Sons, Ltd. [source] Molecular mechanisms of apoptosis induced by magnolol in colon and liver cancer cellsMOLECULAR CARCINOGENESIS, Issue 2 2001Shyr-Yi Lin Abstract Magnolol has been reported to have anticancer activity. In this study we found that treatment with 100 ,m magnolol induced apoptosis in cultured human hepatoma (Hep G2) and colon cancer (COLO 205) cell lines but not in human untransformed gingival fibroblasts and human umbilical vein endothelial cells. Our investigation of apoptosis in Hep G2 cells showed a sequence of associated intracellular events that included (a) increased cytosolic free Ca2+; (b) increased translocation of cytochrome c (Cyto c) from mitochondria to cytosol; (c) activation of caspase 3, caspase 8, and caspase 9; and (d) downregulation of bcl-2 protein. Pretreatment of the cells with the phospholipase C inhibitor 1-[6-[[(17,)-3-methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl]-1 H -pyrrole-2,5-dione (U73122) or the intracellular chelator of Ca2+ 1,2-bis(2-aminophenoxy)ethane- N,N,N,,N, -tetraacetic acid acetoxymethyl ester (BAPTA/AM) inhibited the subsequent magnolol augmentation of [Ca2+]i and also the activation of caspase-8 and caspase-9, so that the occurrence of apoptosis in those cells was greatly reduced. Pretreatment of the cells with ZB4 (which disrupts the Fas response mechanism) also decreased the subsequent magnolol-induced caspase-8 activation and reduced the occurrence of apoptosis. We interpreted these findings to indicate that the above-listed sequence of intracellular events led to the apoptosis seen in Hep G2 cells and that [Ca2+]i, Cyto c, and Fas function as intracellular signals to coordinate those events. © 2001 Wiley-Liss, Inc. [source] The HOG MAP kinase pathway is required for the induction of methylglyoxal-responsive genes and determines methylglyoxal resistance in Saccharomyces cerevisiaeMOLECULAR MICROBIOLOGY, Issue 1 2005Jaime Aguilera Summary A sudden overaccumulation of methylglyoxal (MG) induces, in Saccharomyces cerevisiae, the expression of MG-protective genes, including GPD1, GLO1 and GRE3. The response is partially dependent on the transcriptional factors Msn2p/Msn4p, but unrelated with the general stress response mechanism. Here, we show that the high-osmolarity glycerol (HOG)-pathway controls the genetic response to MG and determines the yeast growth capacity upon MG exposure. Strains lacking the MAPK Hog1p, the upstream component Ssk1p or the HOG-dependent nuclear factor Msn1p, showed a reduction in the mRNA accumulation of MG-responsive genes after MG addition. Moreover, hyperactivation of Hog1p by deletion of protein phosphatase PTP2 enhanced the response, while blocking the pathway by deletion of the MAPKK PBS2 had a negative effect. In addition, the activity of Hog1p affected the basal level of GPD1 mRNA under non-inducing conditions. These effects had a great influence on MG resistance, as hog1, and other HOG-pathway mutants with impaired MG-specific expression displayed MG sensitivity, whereas those with enhanced expression exhibited MG resistance as compared with the wild-type. However, MG does not trigger the overphosphorylation of Hog1p or its nuclear import in the parental strain. Moreover, dual phosphorylation of Hog1p appears to be dispensable in the triggering of the transcriptional response, although a phosphorylable form of Hog1p is fundamental for the transcriptional activity. Overall, our results suggest that the basal activity of the HOG-pathway serves to amplify the expression of MG-responsive genes under non-inducing and inducing conditions, ensuring cell protection against this toxic glycolytic by-product. [source] What neurobiology cannot tell us about addictionADDICTION, Issue 5 2010Harold Kalant ABSTRACT Molecular neurobiological studies have yielded enormous amounts of valuable information about neuronal response mechanisms and their adaptive changes. However, in relation to addiction this information is of limited value because almost every cell function appears to be involved. Thus it tells us only that neurons adapt to ,addictive drugs' as they do to all sorts of other functional disturbances. This information may be of limited help in the development of potential auxiliary agents for treatment of addiction. However, a reductionist approach which attempts to analyse addiction at ever finer levels of structure and function, is inherently incapable of explaining what causes these mechanisms to be brought into play in some cases and not in others, or by self-administration of a drug but not by passive exposure. There is abundant evidence that psychological, social, economic and specific situational factors play important roles in initiating addiction, in addition to genetic and other biological factors. Therefore, if we hope to be able to make predictions at any but a statistical level, or to develop effective means of prevention, it is necessary to devise appropriate integrative approaches to the study of addiction, rather than pursue an ever-finer reductive approach which leads steadily farther away from the complex interaction of drug, user, environment and specific situations that characterizes the problem in humans. [source] Monitoring of protein profiles for the optimization of recombinant fermentation processes using public domain databasesELECTROPHORESIS, Issue 1-2 2003Karin Dürrschmid Abstract The expression of human superoxide dismutase in fed-batch fermentation of E. coli HMS174(DE3)(pET3ahSOD) was studied as model system. Due to the frequently used strong T7 promoter system a high metabolic load is exerted, which triggers stress response mechanisms and finally leads to the differentiation of the host cell. As a consequence, host cell metabolism is partly shifted from growth to survival accompanied by significant alterations of the protein pattern. In terms of process optimization two-dimensional electrophoresis deserves as a powerful tool to monitor these changes on protein level. For the analysis of samples derived from different states of recombinant protein production wide-range Immobiline Dry Strips pH 3,10 were used. In order to establish an efficient procedure for accelerated process optimization and to avoid costly and time-consuming analysis like mass spectrometry (MS), a database approach for the identification of significant changes of the protein pattern was evaluated. On average, 935 spots per gel were detected, whereby 50 are presumably stress-relevant. Out of these, 24 proteins could be identified by using the SWISS-2DPAGE database (www.expasy.ch/ch2d/). The identified proteins are involved in regulatory networks, energy metabolism, purine and pyrimidine nucleotide synthesis and translation. By this database approach, significant fluctuations of individual proteins in relation to recombinant protein production could be identified. Seven proteins show strong alterations (>100%) directly after induction and can therefore be stated as reliable marker proteins for the assessment of stress response. For distinctive interpretation of this highly specific information, a bioinformatic and statistic tool would be essential in order to perceive the role and contribution of individual proteins in stress response. [source] Functional plasticity and robustness are essential characteristics of biological systems: Lessons learned from KLRG1-deficient miceEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 5 2010Stipan Jonjic Abstract Killer cell lectin-like receptor G1 (KLRG1) receptor is considered to be a marker of terminally differentiated NK and T cells and is strongly induced by viral and other infections. KLRG1 is a C-type lectin-like inhibitory receptor, which interacts with members of the cadherin family of molecules leading to the inhibition of T- and NK-cell function. A study in this issue of the European Journal of Immunology addresses the role of KLRG1 in the maturation and differentiation of NK and T cells in vivo. Using KLRG1-deficient mice generated by homologous recombination, the study reveals that KLRG1 is dispensable for NK- and CD8+ T-cell differentiation and function in vivo. This interesting finding is discussed in this Commentary in light of the plasticity and robustness of immune response mechanisms. [source] Virion half-life in chronic hepatitis B infection is strongly correlated with levels of viremia,HEPATOLOGY, Issue 4 2008Maura Dandri Analysis of hepatitis B virus (HBV) kinetics with mathematical models may disclose new aspects of HBV infection and host response mechanisms. To determine the kinetics of virion decay from the blood of patients in different phases of chronic infection, we applied mathematical modeling to real-time polymerase chain reaction assays, which enable quantification of viremia and intrahepatic HBV productivity by measuring both copy number and activity of covalently closed circular DNA (relaxed circular DNA/covalently closed circular DNA) in the liver of 80 untreated chronically active HBV carriers (38 hepatitis B e antigen [HBeAg]-positive and 42 HBeAg-negative individuals). We found that the half-life of circulating virions is very fast (median 46 and 2.5 minutes in HBeAg-positive and HBeAg-negative individuals, respectively) and strongly related to viremia, with clearance rates significantly accelerating as viral loads decrease. To investigate whether immune components can influence the kinetics of virion decay, we analyzed viral dynamics in immunodeficient urokinase-type plasminogen activator chimera mice. Virion half-life in mice (range, 44 minutes to >4 hours) was comparable to estimates determined in high viremic carriers, implying that clearance rates in these patients are mostly determined by common nonspecific mechanisms. Notably, the lack of correlation between virion half-life and viremia in mice indicated that immune components significantly accelerate virion clearance rates in individuals with low titers. Conclusion: Our analyses suggest that both host defense mechanisms and levels of circulating virions affect the kinetics of HBV decay assessed in the serum of chronic carriers. Identification of the factors affecting clearance rates will be important for future antiviral drug developments and it may give insights into the mechanisms involved in clearance of other chronic infections, such as human immunodeficiency virus and hepatitis C virus. (HEPATOLOGY 2008.) [source] Cellular response to oxidative stress: Signaling for suicide and survival,JOURNAL OF CELLULAR PHYSIOLOGY, Issue 1 2002Jennifer L. Martindale Reactive oxygen species (ROS), whether produced endogenously as a consequence of normal cell functions or derived from external sources, pose a constant threat to cells living in an aerobic environment as they can result in severe damage to DNA, protein, and lipids. The importance of oxidative damage to the pathogenesis of many diseases as well as to degenerative processes of aging has becoming increasingly apparent over the past few years. Cells contain a number of antioxidant defenses to minimize fluctuations in ROS, but ROS generation often exceeds the cell's antioxidant capacity, resulting in a condition termed oxidative stress. Host survival depends upon the ability of cells and tissues to adapt to or resist the stress, and repair or remove damaged molecules or cells. Numerous stress response mechanisms have evolved for these purposes, and they are rapidly activated in response to oxidative insults. Some of the pathways are preferentially linked to enhanced survival, while others are more frequently associated with cell death. Still others have been implicated in both extremes depending on the particular circumstances. In this review, we discuss the various signaling pathways known to be activated in response to oxidative stress in mammalian cells, the mechanisms leading to their activation, and their roles in influencing cell survival. These pathways constitute important avenues for therapeutic interventions aimed at limiting oxidative damage or attenuating its sequelae. Published 2002 Wiley-Liss, Inc. [source] Skills under threat: the case of HIV/AIDS in the mining industry in ZimbabweJOURNAL OF INTERNATIONAL DEVELOPMENT, Issue 5 2006Caroline N. Matangi Abstract The Zimbabwe mining industry is currently battling to arrest further spread of the HIV/AIDS crisis in workplaces, especially its impact on labour productivity. Labour in the closed community of mines has been greatly susceptible to HIV/AIDS infection. The current AIDS incidence in the mine sites is estimated at a weighted average of 15,per,cent amongst miners, with the largest category of workers,the 30,39 years age group,also constituting the worst affected category. Given the current state of the country's economy and consequently its adverse impact on the lifestyle of miners, the pandemic is expected to increase. This paper builds on the work of the ILO (1995) involving a survey of 18 various firms/institutions. The survey was carried out in Zambia in order to assess the impact of HIV/AIDS on the productive labour force. The survey revealed that many of the firms are experiencing irregular work attendance, ,wasted' training as some of the trained workers are constantly ill or die, high medical bills, funeral costs and reduced productivity and profits. An analysis of data on the main causes of death in 1993 shows that at least 61.8,per,cent of deaths could be attributed to causes that are very closely related to HIV/AIDS complications. Based on points highlighted by respondents and analysis of symptoms suffered, it was observed that HIV/AIDS tended to affect most general workers (36.8,per,cent), followed by the lower management (30.9,per,cent) and the middle management (20.6,per,cent). Comparatively, 11.8,per,cent of the deaths in 1993 belonged to the top management. Although it is hard to appreciate the meaning of the figures without knowledge of the number of people in each category, it nevertheless helps to form a clear picture of the impact of HIV/AIDS on industry. This paper seeks to further investigate the impact of HIV/AIDS on the productive labour force, by focusing on one particular industry,mining,using a blend of research methods to collect the data. This paper examines the impact of HIV/AIDS on the productive labour force and management responses. It forms part of the findings of data gathered in 2001 in the mining industry in Zimbabwe, to examine factors affecting management responses to HIV/AIDS in the mine sites. Zimbabwe is a country with a complex historical legacy of mine labour. This phenomenon can largely be attributed to the production oriented nature of the mining industry. Mines focus mainly on mineral extraction and as a result the bulk of mine workers tend to be production workers whose skills have developed over long periods of time. Production workers on mines have a tradition of long-term employment. This phenomenon has meant that labour in the mines is hard to replace as a result of skills, especially tacit knowledge, acquired over many years. Thus while the recent closure of some gold mines, largely due to low commodity prices, has meant that more miners are available in the labour market, this situation has not necessarily eased the process of replacing labour lost to the HIV/AIDS epidemic, as certain skills are firm specific. Production workers are predominantly male with the bulk falling in the 35,39 years age group. Most mine workers reside in mine villages, a colonial legacy that ensured miners were close to the workplace. The village system is a system of housing labourers, which demonstrates capitalistic methods of controlling labour and minimising costs. Of significance in this study's background is how the village system has come to be viewed as a factor in the spread of HIV/AIDS in the mining communities, because of its ,closed' nature. It is against this complex historical backdrop that the paper turns to examine the impact of the HIV/AIDS pandemic on production workers and management responses to the crisis using the Resource Based View of the Firm model (RBV), one of the theories in the Strategic Human Resource Management (SHRM) tradition. RBV was chosen for this study out of many HRM models that exist, because this theory, in particular, explains why it is advantageous for sites to use their ,unique' firm based resources in order to achieve sustainable competitive advantage. Given this rationale it was, therefore, presumed that this theory would best apply in mines battling with the adverse impact of HIV/AIDS on productivity, especially in the light of the harsh national economic climate, which would likely place limitations on response mechanisms. Further, the issue of firm-specific skills was also taken into consideration as an important factor in the mines, limiting their ability to resort to external solutions. Thus, given these factors, RBV was deemed the most appropriate model. The study finds that the pandemic depresses labour productivity through a number of significant ways: increased rate of HIV/AIDS induced absenteeism gradual labour turnover as a result of AIDS induced morbidity; and consequently declining skills availability, particularly firm-specific skills. Maintaining labour productivity in the face of gradually diminishing skills and indisposed labour will be key to softening the adverse economic consequences of the pandemic in the mines. To reduce the threat to labour productivity, mines must find ways of utilising, to the maximum extent practicable, existing skills. Results indicate that a move towards the utilisation of existing miners is the most favoured response mechanism in most mines. Utilising existing miners enables mines from spending financial resources on avoidable recruitment and training and quite often mechanisation, which may not necessarily be compatible with the old infrastructure in certain mines. Copyright © 2006 John Wiley & Sons, Ltd. [source] Rural household responses to fuelwood scarcity in Nyando District, KenyaLAND DEGRADATION AND DEVELOPMENT, Issue 1 2003I. O. Mahiri Abstract The fuelwood debate over supply,demand balances is well rehearsed; and the use of simplistic linear models to explain supply,demand differentials hardly captures the complex patterns of use and dynamics of fuelwood in the rural household. This paper shows that households in Nyando District have evolved sophisticated local response mechanisms and strategies in coping with the fuelwood scarcity. Data collected through a multi-method approach revealed, among others, a higher percentage of planted trees in Kochogo than in Awasi study sites. Despite this high proliferation of trees, rural households in Kochogo still identified fuelwood scarcity as a growing problem. The seeming ,abundance' of trees is not synonymous with the supply of fuelwood, or the alleviation of fuelwood scarcity. Rural households in Kochogo therefore resort to the market to purchase fuelwood, as well as adapt various fuel-saving strategies and mechanisms to cope with the apparent scarcity. The purchase of crop residues from the market is a strong indicator of this scarcity, being simply lack of access to or entitlement to trees. The situation is different in Awasi, where there is a higher percentage of natural trees and clump bushes, which provide a relative abundance of fuelwood. This condition has encouraged local households not to keep a stock of fuelwood, but simply to collect from nearby bushes when required. Copyright © 2002 John Wiley & Sons, Ltd. [source] Cellular response mechanisms in Pseudomonas aeruginosa PseA during growth in organic solventsLETTERS IN APPLIED MICROBIOLOGY, Issue 3 2009R. Gaur Abstract Aims:, Solvent-tolerant bacteria have emerged as a new class of micro-organisms able to grow at high concentrations of toxic solvents. Such bacteria and their solvent-stable enzymes are perceived to be useful for biotransformations in nonaqueous media. In the present study, the solvent-responsive features of a lipase,producing, solvent-tolerant strain Pseudomonas aeruginosa PseA have been investigated to understand the cellular mechanisms followed under solvent-rich conditions. Methods and Results:, The solvents, cyclohexane and tetradecane with differing log P -values (3·2 and 7·6 respectively), have been used as model systems. Effect of solvents on (i) the cell morphology and structure (ii) surface hydrophobicity and (iii) permeability of cell membrane have been examined using transmission electron microscopy, atomic force microscopy and other biochemical techniques. The results show that (i) less hydrophobic (low log P -value) solvent cyclohexane alters the cell membrane integrity and (ii) cells adapt to organic solvents by changing morphology, size, permeability and surface hydrophobicity. However, no such changes were observed in the cells grown in tetradecane. Conclusions:, It may be concluded that P. aeruginosa PseA responds differently to solvents of different hydrophobicities. Bacterial cell membrane is more permeable to less hydrophobic solvents that eventually accumulate in the cytoplasm, while highly hydrophobic solvents have lesser tendency to access the membrane. Significance and Impact of the Study:, To the best of our knowledge, these are first time observations that show that way of bacterial solvent adaptability depends on nature of solvent. Difference in cellular responses towards solvents of varying log P -values (hydrophobicity) might prove useful to search for a suitable solvent for carrying out whole-cell biocatalysis. [source] Changes in lymphocyte populations in suckling piglets during primary infections with Isospora suisPARASITE IMMUNOLOGY, Issue 4 2010H. L. WORLICZEK Summary Isospora suis, a common intestinal parasite of piglets, causes neonatal porcine coccidiosis, which results in reduced and uneven weaning weights and economic losses in pig production. Nevertheless, there are no detailed studies available on the immune response to I. suis. The aim of this study was to carry out phenotypical characterization of lymphocytes during primary infections on day 3 after birth. Infected and noninfected piglets were investigated between days 7 and 16 after birth. Lymphocytes from the blood, spleen and mesenteric lymph nodes (flow cytometry) and of the jejunal mucosa (immunohistochemistry) were analysed. A decrease in T cells, especially with the phenotype of resting T-helper cells, T-cell receptor-,,-T cells, and regulatory T cells in the blood, spleen and mesenteric lymph nodes was noticeable. An increase in cells with the phenotype of natural killer cells in the spleen of infected animals was found, and the subset of TcR-,,-T cells was strongly increased in the gut mucosa. Our findings suggest an accelerated migration of those cells into the gut. This study provides a strong indication for the involvement of adaptive and innate immune response mechanisms in the primary immune response to I. suis, especially of TcR-,,-T cells as a linkage between innate and adaptive immunity. [source] Cutaneous effects of infrared radiation: from clinical observations to molecular response mechanismsPHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 5 2003Stefan M. Schieke Human skin is exposed to infrared (IR) radiation (760 nm,1 mm) from natural as well as artificial sources that are increasingly used for cosmetic or medical purposes. Epidemiological data and clinical observations, however, indicate that IR radiation cannot be considered as totally innocuous to human skin. In particular, IR radiation, similar to ultraviolet radiation, seems to be involved in photoaging and potentially also in photocarcinogenesis. The molecular consequences resulting from IR exposure are virtually unknown. Recent studies, however, have begun to shed light on the basic molecular processes such as cellular signal transduction and gene expression triggered by exposure to IR radiation. In response to IR irradiation, mitogen-activated protein kinase signaling pathways were activated mediating the upregulation of matrix metalloproteinase-1 expression. This previously unrecognized molecular ,IR response' shows that IR radiation is capable of specifically interfering with cellular functions and provides a molecular basis for biological effects of IR on human skin. [source] Next generation of elevated [CO2] experiments with crops: a critical investment for feeding the future worldPLANT CELL & ENVIRONMENT, Issue 9 2008ELIZABETH A. AINSWORTH ABSTRACT A rising global population and demand for protein-rich diets are increasing pressure to maximize agricultural productivity. Rising atmospheric [CO2] is altering global temperature and precipitation patterns, which challenges agricultural productivity. While rising [CO2] provides a unique opportunity to increase the productivity of C3 crops, average yield stimulation observed to date is well below potential gains. Thus, there is room for improving productivity. However, only a fraction of available germplasm of crops has been tested for CO2 responsiveness. Yield is a complex phenotypic trait determined by the interactions of a genotype with the environment. Selection of promising genotypes and characterization of response mechanisms will only be effective if crop improvement and systems biology approaches are closely linked to production environments, that is, on the farm within major growing regions. Free air CO2 enrichment (FACE) experiments can provide the platform upon which to conduct genetic screening and elucidate the inheritance and mechanisms that underlie genotypic differences in productivity under elevated [CO2]. We propose a new generation of large-scale, low-cost per unit area FACE experiments to identify the most CO2 -responsive genotypes and provide starting lines for future breeding programmes. This is necessary if we are to realize the potential for yield gains in the future. [source] Odorants as cell-type specific activators of a heat shock response in the rat olfactory mucosaTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 4 2001Virginian McMillan Carr Abstract Heat shock, or stress, proteins (HSPs) are induced in response to conditions that cause protein denaturation. Activation of cellular stress responses as a protective and survival mechanism is often associated with chemical exposure. One interface between the body and the external environment and chemical or biological agents therein is the olfactory epithelium (OE). To determine whether environmental odorants affect OE HSP expression, rats were exposed to a variety of odorants added to the cage bedding. Odorant exposure led to transient, selective induction of HSP70, HSC70, HSP25, and ubiquitin immunoreactivities (IRs) in supporting cells and subepithelial Bowman's gland acinar cells, two OE non-neuronal cell populations involved with inhalant biotransformation, detoxification, and maintenance of overall OE integrity. Responses exhibited odor specificity and dose dependency. HSP70 and HSC70 IRs occurred throughout the apical region of supporting cells; ubiquitin IR was confined to a supranuclear cone-shaped region. Electron microscopic examination confirmed these observations and, additionally, revealed odor-induced formation of dense vesicular arrays in the cone-like regions. HSP25 IR occurred throughout the entire supporting cell cytoplasm. In contrast to classical stress responses, in which the entire array of stress proteins is induced, no increases in HSP40 and HSP90 IRs were observed. Extended exposure to higher odorant doses caused prolonged activation of the same HSP subset in the non-neuronal cells and severe morphological damage in both supporting cells and olfactory receptor neurons (ORNs), suggesting that non-neuronal cytoprotective stress response mechanisms had been overwhelmed and could no longer adequately maintain OE integrity. Significantly, ORNs showed no stress responses in any of our studies. These findings suggest a novel role for these HSPs in olfaction and, in turn, possible involvement in other normal neurophysiological processes. J. Comp. Neurol. 432:425,439, 2001. © 2001 Wiley-Liss, Inc. [source] Resolving the differences in plant burial responsesAUSTRAL ECOLOGY, Issue 1 2010MATTHEW E. GILBERT Abstract Burial is one of the major factors influencing plant ecology in deserts and coastal areas. Consequently, many studies have measured the responses of dune plants to sand burial. However, there remains little agreement about the mechanisms and characteristics constituting the burial response of plants. In particular, stimulation of growth has been reported as the most common plant burial response; however, stimulation has not been reported consistently among studies. Here, a literature survey showed that the depth of burial relative to the height of the plant determined whether the growth of a species was stimulated by burial. Growth stimulation was limited to shallow burial depths, while burial depths greater than the height of the plant consistently resulted in reduced growth. As studies used widely differing burial depths or units of growth measurement, the variation in reported stimulation of plant growth can be partly attributed to differences in experimental procedure. The stimulation of growth in many species was accompanied by an increase in photosynthesis over a limited period and by a shift in biomass allocation from root to shoot. Most plants demonstrated stimulated growth (up to 200%) in response to shallow burial indicating that some burial response mechanisms are general to many species. However, a few specialist dune species displayed a much greater ability to respond to burial (up to 700% stimulation of plant mass). Although allocation shifts and increased photosynthesis have been shown to be associated with dune plant burial response, there remains a need for field measurements that focus on the diversity of mechanisms underlying plant response to burial. [source] Model identification in presence of incomplete information by generalized principal component analysis: Application to the common and differential responses of Escherichia coli to multiple pulse perturbations in continuous, high-biomass density cultureBIOTECHNOLOGY & BIOENGINEERING, Issue 4 2009Daniel V. Guebel Abstract In a previous report we described a multivariate approach to discriminate between the different response mechanisms operating in Escherichia coli when a steady, continuous culture of these bacteria was perturbed by a glycerol pulse (Guebel et al., 2009, Biotechnol Bioeng 102: 910,922). Herein, we present a procedure to extend this analysis when multiple, spaced pulse perturbations (glycerol, fumarate, acetate, crotonobetaine, hypersaline plus high-glycerol basal medium and crotonobetaine plus hypersaline basal medium) are being assessed. The proposed method allows us to identify not only the common responses among different perturbation conditions, but to recognize the specific response for a given stimulus even when the dynamics of the perturbation is unknown. Components common to all conditions are determined first by Generalized Principal Components Analysis (GPCA) upon a set of covariance matrices. A metrics is then built to quantify the similitude distance. This is based on the degree of variance extraction achieved for each variable along the GPCA deflation processes by the common factors. This permits a cluster analysis, which recognizes several compact sub-sets containing only the most closely related responsive groups. The GPCA is then run again but is restricted to the groups in each sub-set. Finally, after the data have been exhaustively deflated by the common sub-set factors, the resulting residual matrices are used to determine the specific response factors by classical principal component analysis (PCA). The proposed method was validated by comparing its predictions with those obtained when the dynamics of the perturbation was determined. In addition, it showed to have a better performance than the obtained with other multivariate alternatives (e.g., orthogonal contrasts based on direct GPCA, Tucker-3 model, PARAFAC, etc.). Biotechnol. Bioeng. 2009; 104: 785,795 © 2009 Wiley Periodicals, Inc. [source] | ||||||||||||||||