Stress Adaptation Mechanisms Research Articles

Photosynthesis and lipid composition of the Antarctic endemic rhodophyte Palmaria decipiens: effects of changing light and temperature levels

In coastal waters, Antarctic rhodophytes are exposed to harsh environmental conditions throughout the year, like low water temperatures ranging from −1.8°C to 2°C and high light during the summer season. Photosynthetic performance under these conditions may be affected by slowed down enzymatic reactions and the increased generation of reactive oxygen species. The consequence might be a chronic photoinhibition of photosynthetic primary reactions related to increased fragmentation of the D1 reaction centre protein in photosystem II. It is hypothesized that changes in lipid composition of biomembranes may represent an adaptive trait to maintain D1 turnover in response to temperature variation. The interactive effects of high light and low temperature were studied on an endemic Antarctic red alga, Palmaria decipiens, sampled from two shore levels, intertidal and subtidal, and exposed to mesocosm experiments using two levels of natural solar radiation and two different temperature regimes (2–5°C and 5–10°C). During the experimental period of 23 days, maximum quantum yield of photosynthesis decreased in all treatments, with the intertidal specimens exposed at 5–10°C being most affected. On the pigment level, a decreasing ratio of phycobiliproteins to chlorophyll a was found in all treatments. A pronounced decrease in D1 protein concentration occurred in subtidal specimens exposed at 2–5°C. Marked changes in lipid composition, i.e. the ratio of saturated to unsaturated fatty acids, indicated an effective response of specimens to temperature change. Results provide new insights into mechanisms of stress adaptation in this key species of shallow Antarctic benthic communities.

Heat shock proteins in the mechanisms of stress adaptation in Baikal amphipods and palearctic Gammarus lacustris Sars. I. HSP70 family

Heat shock proteins in the mechanisms of stress adaptation in Baikal amphipods and palearctic Gammarus lacustris Sars. I. HSP70 family

Transcriptional responses in Honey Bee larvae infected with chalkbrood fungus

BackgroundDiseases and other stress factors working synergistically weaken honey bee health and may play a major role in the losses of bee populations in recent years. Among a large number of bee diseases, chalkbrood has been on the rise. We present here the experimental identification of honey bee genes that are differentially expressed in response to infection of honey bee larvae with the chalkbrood fungus, Ascosphaera apis.ResultsWe used cDNA-AFLP ®Technology to profile transcripts in infected and uninfected bee larvae. From 64 primer combinations, over 7,400 transcriptionally-derived fragments were obtained A total of 98 reproducible polymorphic cDNA-AFLP fragments were excised and sequenced, followed by quantitative real-time RT-PCR (qRT-PCR) analysis of these and additional samples.We have identified a number of differentially-regulated transcripts that are implicated in general mechanisms of stress adaptation, including energy metabolism and protein transport. One of the most interesting differentially-regulated transcripts is for a chitinase-like enzyme that may be linked to anti-fungal activities in the honey bee larvae, similarly to gut and fat-body specific chitinases found in mosquitoes and the red flour beetle. Surprisingly, we did not find many components of the well-characterized NF-κB intracellular signaling pathways to be differentially-regulated using the cDNA-AFLP approach. Therefore, utilizing qRT-PCR, we probed some of the immune related genes to determine whether the lack of up-regulation of their transcripts in our analysis can be attributed to lack of immune activation or to limitations of the cDNA-AFLP approach.ConclusionsUsing a combination of cDNA-AFLP and qRT-PCR analyses, we were able to determine several key transcriptional events that constitute the overall effort in the honey bee larvae to fight natural fungal infection. Honey bee transcripts identified in this study are involved in critical functions related to transcriptional regulation, apoptotic degradation of ubiquitinated proteins, nutritional regulation, and RNA processing. We found that immune regulation of the anti-fungal responses in honey bee involves highly coordinated activation of both NF-κB signaling pathways, leading to production of anti-microbial peptides. Significantly, activation of immune responses in the infected bee larvae was associated with down-regulation of major storage proteins, leading to depletion of nutritional resources.

Phenotyping approaches for physiological breeding and gene discovery in wheat

AbstractConceptual models of drought‐adaptive traits have been used in breeding to accumulate complementary physiological traits (PT) in selected progeny, resulting in distribution of advanced lines to rain‐fed environments worldwide by the International Maize and Wheat Improvement Center (CIMMYT). Key steps in PT breeding at CIMMYT include characterisation of crossing block lines for stress adaptive mechanisms, strategic crossing among parents that encompass as many target traits as possible and early generation selection (EGS) of bulks for canopy temperature (CT). The approach has been successful using both elite × elite crosses as well as three way crosses involving stress adapted landraces. Other EGS techniques that are amenable to high throughput include measurement of spectral reflectance indices and stomatal aperture‐related traits. Their genetic‐ and cost‐effectiveness are supported by realisation of genetic yield gains in response to trait selection, and by economic analysis, respectively. Continual reselection within restricted gene pools is likely to lead to diminishing returns, however, exotic parents can be used to introduce new allelic diversity. Examples include landraces from the primary gene pool, and products of inter‐specific hybridisation with the secondary gene pool consisting of closely related wheat genomes. Both approaches have been successful in introducing stress‐adaptive traits. The main problem with knowing which genetic resource to use in wide‐crossing is the uncertainty with which phenotypic expression can be extrapolated from one genome/genepool to another because of their unimproved or undomesticated genetic backgrounds. Nonetheless, their PT expression can be measured and used as a basis for investing in crossing or wide crossing. Discovering the genetic basis of PT is highly complex because putative QTLs may interact with environment and genetic background, including genes of major effect. Detection of QTLs was improved in mapping populations where flowering time was controlled, while new mapping populations have been designed by screening potential parents that do not contrast in the Rht, Ppd and Vrn alleles. Association genetics mapping is another approach that can be employed for gene discovery using exclusively agronomically improved material, thereby minimising the probability of identifying yield QTLs whose alleles have been already improved by conventional breeding.

Effect of water stress on growth, osmotic adjustment, cell wall elasticity and water-use efficiency in Spartina alterniflora

In the northern spring–summer season of 2004–2005, vegetative propagated plants of Spartina alterniflora were grown under control and water stress conditions on the Mediterranean sea shore of the south-east of Tunis. Control plants were irrigated every week and water stress plants were irrigated until the soil achieved 50% (mild stress) and 25% (severe stress) field capacity (FC). Dry and fresh weight at the whole plant level (g plant −1), shoot to root ratio on dry and fresh weight, photosynthesis ( A), transpiration rate ( E), instantaneous water-use efficiency (WUE i), leaf water potential ( Ψw), leaf water content (WC), osmotic potential at full turgor ( Ψs 100), osmotic potential at turgor loss point ( Ψs 0), osmotic adjustment (OA), proline, sugars, inorganic compounds and cell wall elasticity (CWE) were evaluated during a period of 6 days period between 82 and 90 days after the beginning of treatment (DAT). Plants grown under severe and mild-water stress showed lower Ψw than in control plants with values that averaged −3.1, −1.6 and −0.9 MPa, respectively. S. alterniflora plants submitted to mild-water stress exhibited OA and a decrease in CWE. However, under severe water stress the OA was not observed and CWE also decreased, but it was higher than in the mild-water stress. OA was mainly explained by the accumulation of nitrates, sugars and at a lesser degree, proline. S. alterniflora had a strong decline of the dry and fresh weight of the whole plant associated to a marked decrease of photosynthesis ( A) and transpiration ( E) in response to water stress, although WUE i was increased. These results suggest that OA and WUE i can be important components of the water stress adaptation mechanism in this species, but they are not sufficient enough to contribute to resistance to water stress.

Stress, sublethal injury, resuscitation, and virulence of bacterial foodborne pathogens.

Environmental stress and food preservation methods (e.g., heating, chilling, acidity, and alkalinity) are known to induce adaptive responses within the bacterial cell. Microorganisms that survive a given stress often gain resistance to that stress or other stresses via cross-protection. The physiological state of a bacterium is an important consideration when studying its response to food preservation techniques. This article reviews the various definitions of injury and stress, sublethal injury of bacteria, stresses that cause this injury, stress adaptation, cellular repair and response mechanisms, the role of reactive oxygen species in bacterial injury and resuscitation, and the potential for cross-protection and enhanced virulence as a result of various stress conditions.

International conference “Photosynthesis in the Global Perspective” held in honor of Govindjee, November 27–29, 2008, Indore, India

An International conference ‘‘Photosynthesis in the Global perspective’’ was held in Indore, India, during November 27–29, 2008, in honor of Professor Govindjee. The conference provided an opportunity to felicitate him for the numerous significant and outstanding contributions in the field of photosynthesis research (also see Eaton-Rye 2007a, b). His dedication for communicating photosynthesis and his passion for the ‘‘History of Photosynthesis Research’’ has been commendable. He has been already recognized with the first Lifetime Achievement Award of the Rebeiz Foundation for Basic Research (Rebeiz et al. 2007) and with the prestigious 2007 Communication Award of the International Society of Photosynthesis Research (ISPR) (see Blankenship 2007). Just before the conference in Indore, University of Illinois recognized him on October 24, 2008, with an LAS (Liberal Arts and Sciences) Alumni Achievement Award (see http://www.las.illinois.edu/alumni/magazine/articles/2009/ govindjee). Figure 1A shows Govindjee’s photograph with three of his graduate students (George Papageorgiou, Julian Eaton-Rye and Prasanna Mohanty) who actively participated at the Indore Conference. Figure 1B shows a group photograph of Govindjee with many of the participants at the conference. The conference covered all the important aspects of photosynthesis, especially their relationship to global issues. Topics included: photobiology, structure and function of Photosystems I and II, stress responses & adaptive mechanisms, plant productivity, and artificial photosynthesis. Advances in structural and functional aspects of Photosystem II (PS II, the water-plastoquinone oxido-reductase, the only system on Earth that is capable of oxidizing water to molecular oxygen) was at the heart of many talks. This was highly appropriate for this celebration since Govindjee and co-workers were the first to measure the primary photochemistry of PS II, to provide an understanding of the PS II light emission from plants, algae, and cyanobacteria, to provide the theory of thermoluminescence from PS II, and to establish the unique role of bicarbonate/carbonate on the electron acceptor side of PS II. Stress responses of plants and their adaptive strategy to cope with stress was another key issue at the conference. There were 32 talks and about 45 posters, presented by both established and young scientists from about 12 countries (listed alphabetically): Australia, Azerbaijan, Canada, (The) Czech Republic, Finland, Hungary, India, Japan, Korea, New Zealand, Switzerland, UK, and USA. Speakers included (listed alphabetically): Arjun Tiwari, Asako Kawamori, Atipally Reddy, Baishnab Tripathy, Basanti Biswal, Bhumi Nath Tripathy, Debashish Banerji, Eva Mari Aro, Gyozo Garab, Hiroyuki Mino, James Barber, Julian EatonRye, K Padamsree, Kastoori Hingorani, Kumud Mishra, Louis Sherman, M.J. Baig, Michael Seibert, Munna Singh, Norm Huner, Pandit Vidyasagar, Prabhat Kumar Sharma, Prasanna Mohanty, Ralph Gasanov, Renu Khanna-Chopra, Reto Strasser, Shigeru Itoh, Subramanyam Rajagopal, Sujata Mishra, Suvendra Bagchi, Toshi Nagata and Uday Pathre. The guest of honor at the inaugural session was James Barber, President of International Society of Photosynthesis Research (ISPR). Govindjee delivered his inaugural talk Prasanna Mohanty—Formerly Professor of School of Life Science, Jawaharlal Nehru University, New Delhi, India.

The molecular and cellular basis of infection—Perspectives from the first advanced summer school in Africa

The molecular and cellular basis of infection—Perspectives from the first advanced summer school in Africa

Dissecting the mechanisms of environmental stress adaptation: A systems biology approach

Dissecting the mechanisms of environmental stress adaptation: A systems biology approach

Transcript profiles uncover temporal and stress-induced changes of metabolic pathways in germinating sugar beet seeds

BackgroundWith a cultivation area of 1.75 Mio ha and sugar yield of 16.7 Mio tons in 2006, sugar beet is a crop of great economic importance in Europe. The productivity of sugar beet is determined significantly by seed vigour and field emergence potential; however, little is known about the molecular mechanisms underlying these traits. Both traits exhibit large variations within sugar beet germplasm that have been difficult to ascribe to either environmental or genetic causes. Among potential targets for trait improvement, an enhancement of stress tolerance is considered because of the high negative influence of environmental stresses on trait parameters. Extending our knowledge of genetic and molecular determinants of sugar beet germination, stress response and adaptation mechanisms would facilitate the detection of new targets for breeding crop with an enhanced field emergence potential.ResultsTo gain insight into the sugar beet germination we initiated an analysis of gene expression in a well emerging sugar beet hybrid showing high germination potential under various environmental conditions. A total of 2,784 ESTs representing 2,251 'unigenes' was generated from dry mature and germinating seeds. Analysis of the temporal expression of these genes during germination under non-stress conditions uncovered drastic transcriptional changes accompanying a shift from quiescent to metabolically active stages of the plant life cycle. Assay of germination under stressful conditions revealed 157 genes showing significantly different expression patterns in response to stress. As deduced from transcriptome data, stress adaptation mechanisms included an alteration in reserve mobilization pathways, an accumulation of the osmoprotectant glycine betaine, late embryogenesis abundant proteins and detoxification enzymes. The observed transcriptional changes are supposed to be regulated by ABA-dependent signal transduction pathway.ConclusionThis study provides an important step toward the understanding of main events and metabolic pathways during germination in sugar beet. The reported alterations of gene expression in response to stress shed light on sugar beet stress adaptation mechanisms. Some of the identified stress-responsive genes provide a new potential source for improvement of sugar beet stress tolerance during germination and field emergence.

β-Endorphin concentration in colostrums of Burkinabe and Sicilian women

Objective Endorphins (EPs) present in human colostrum may be relevant for immediate postnatal fetal adaptation because this compound is involved in stress response and adaptation mechanisms. Endorphin levels in human colostrum are two-fold greater than corresponding maternal plasma levels; however, the high endorphin levels in human milk decrease as lactation continues. The aim of this study was to determine the β-EP concentration in colostrums of women residing in Burkina Faso and Sicily. In addition, we investigated the source of potential differences in β-EP levels between these populations, especially ethnic sources of these deviations. Methods The concentration of β-EP was determined in the colostrum from the first 3 d subsequent to delivery by an enzyme immunoassay as immunoreactive material (IRM). Results The production of β-EP in the colostrum was significantly higher in Burkinabe mothers (0.83 ± 0.04 ng/mL) than in Sicilian mothers (0.31 ± 0.02 ng/mL) at 24 h after delivery. Colostrum levels of β-EP declined progressively during the first 3 d after delivery in both populations (0.64 ± 0.1 and 0.28 ± 0.015 ng/mL, respectively, at 72 h). The level of β-EP-IRM correlated significantly with pain and psychological involvement during and after delivery. In addition, the correlation between β-EP-IRM and length of stage II of labor was significant ( P < 0.0001) in the colostrums of Sicilian mothers who received ergot derivatives, episiorrhaphy, and child birth preparation. The correlation between β-EP-IRM and length of stage II was less significant ( P < 0.001) in the colostrums of Burkinabe mothers who received neither ergot derivatives nor child birth preparation. Conclusion During the first 3 d after labor the β-EP-IRM concentration in the colostrums of Burkinabe mothers differs from that of Sicilians. In addition, because Burkinabe women produce a larger volume of colostrum, their newborns receive, during the first days of life, a larger absolute amount of β-EP-IRM, likely resulting in better postnatal fetal adaptation.

Cardiovascular responses to cognitive stress in patients with migraine and tension-type headache

BackgroundThe purpose of this study was to investigate the temporal relationship between autonomic changes and pain activation in migraine and tension-type headache induced by stress in a model relevant for everyday office-work.MethodsWe measured pain, blood pressure (BP), heart rate (HR) and skin blood flow (BF) during and after controlled low-grade cognitive stress in 22 migraineurs during headache-free periods, 18 patients with tension-type headache (TTH) and 44 healthy controls. The stress lasted for one hour and was followed by 30 minutes of relaxation.ResultsCardiovascular responses to cognitive stress in migraine did not differ from those in control subjects. In TTH patients HR was maintained during stress, whereas it decreased for migraineurs and controls. A trend towards a delayed systolic BP response during stress was also observed in TTH. Finger BF recovery was delayed after stress and stress-induced pain was associated with less vasoconstriction in TTH during recovery.ConclusionIt is hypothesized that TTH patients have different stress adaptive mechanisms than controls and migraineurs, involving delayed cardiovascular adaptation and reduced pain control system inhibition.

Reduced eIF2α phosphorylation and increased proapoptotic proteins in aging

A decline in relative levels and phosphorylation of many of the eukaryotic initiation factors (eIFs) including S6, the 40S ribosomal subunit protein in many of the rat tissues during chronological aging is accompanied by elevated levels of eIF2α kinases, such as PKR and PERK, but not their activity. Concomitant with increased eIF2α phosphorylation, young tissues displayed a higher level of eIF2B to tolerate the toxic effect of eIF2α phosphorylation on translation, ATF4, a b-zip transcriptional factor that is produced as part of the gene expression programe in response to eIF2α phosphorylation, and BiP, an endoplasmic reticulum (ER) molecular chaperone and regulator of ER stress sensors. Decline in eIF2α phosphorylation in aged tissues is associated with a higher level of GADD34, a subunit of eIF2α phosphatase, and proapoptotic proteins like CHOP/GADD153 and phospho JNK, suggesting that young tissues possess an efficient ER stress adaptive mechanism that declines with aging.

Effect of drought stress on the osmotic adjustment, cell wall elasticity and cell volume of six cultivars of common beans ( Phaseolus vulgaris L.)

In the southern spring–summer season of 2001–2002 six cultivars (Orfeo, Arroz Tuscola, Barbucho, Coscorrón, Pinto and Tórtola) of common beans ( Phaseolus vulgaris L.) were grown under two frequencies of irrigation in the central zone of Chile. Control plants were irrigated every 7 days and water stress plants were irrigated every 21 days. Leaf water potential ( Ψ W), leaf relative water content (RWC), turgid weight to dry weight ratio (TW/DW), osmotic potential at full turgor ( ψ S 100 ), osmotic adjustment (OA), elasticity module of the cell wall ( ɛ) and cell size of the palisade and spongy tissue were evaluated at 74–76 days after sowing (DAS) in completely developed leaves. Water stressed plants showed lower Ψ W than in control plants in all the varieties with values that averaged −1.4 and −0.9 MPa, respectively. According to the Drought Resistance Index (DRI) calculated from field measurements, among the cultivars studied, Orfeo was the most resistant to water stress and Arroz Tuscola, the most susceptible. A close negative relationship between leaf TW/DW and DRI under water stress conditions was observed ( r 2 = 0.63). Leaf TW/DW decreased considerably with water stress in cultivar Orfeo (15%) but the decrease was higher in Tórtola (22%), and there was also a decrease (although smaller) in Pinto (11%). Arroz Tuscola under stress did not present an important change in TW/DW, but presented one of the highest values of TW/DW. There was a strong negative correlation between DRI and palisade cell size under water stress conditions ( r 2 = 0.85) and a strong positive one between palisade cell size and TW/DW ( r 2 = 0.86) thus higher DRI was associated with small palisade cell size and small TW/DW. The most resistant cultivar Orfeo did not show a decrease in ψ S 100 calculated from the pressure–RWC relationships and its resistance was not associated with maintenance of leaf TW/DW under water stress. ψ S 100 calculated from the pressure–RWC relationships decreased only in the cultivar Coscorrón. Cultivar Orfeo showed a strong decrease (35%) of ɛ, in association to a higher cell wall elasticity (CWE) and as consequence maintained better its cell turgescence but this was also the case of Tórtola (56%) and Pinto (34%) and to a lesser extent of Barbucho (18%). This was not the case for Arroz Tuscola where ɛ and CWE were not changed. These results suggest that CWE and to a lesser extent leaf TW/DW can be important components of the water stress adaptation mechanism in this specie that could contribute to the higher resistance to water stress of Orfeo compared to Arroz Tuscola.

Response of Lactobacillus helveticus PR4 to heat stress during propagation in cheese whey with a gradient of decreasing temperatures.

The heat stress response was studied in Lactobacillus helveticus PR4 during propagation in cheese whey with a gradient of naturally decreasing temperature (55 to 20 degrees C). Growth under a gradient of decreasing temperature was compared to growth at a constant temperature of 42 degrees C. Proteinase, peptidase, and acidification activities of L. helveticus PR4 were found to be higher in cells harvested when 40 degrees C was reached by a gradient of decreasing temperature than in cells grown at constant temperature of 42 degrees C. When cells grown under a temperature gradient were harvested after an initial exposure of 35 min to 55 degrees C followed by decreases in temperature to 40 (3 h), 30 (5 h 30 min), or 20 degrees C (13 h 30 min) and were then compared with cells grown for the same time at a constant temperature of 42 degrees C, a frequently transient induction of the levels of expression of 48 proteins was found by two-dimensional electrophoresis analysis. Expression of most of these proteins increased following cooling from 55 to 40 degrees C (3 h). Sixteen of these proteins were subjected to N-terminal and matrix-assisted laser desorption ionization-time of flight mass spectrometry analyses. They were identified as stress proteins (e.g., DnaK and GroEL), glycolysis-related machinery (e.g., enolase and glyceraldehyde-3-phosphate dehydrogenase), and other regulatory proteins or factors (e.g., DNA-binding protein II and ATP-dependent protease). Most of these proteins have been found to play a role in the mechanisms of heat stress adaptation in other bacteria.

Changes of anti-oxidative enzymes and MDA content under soil water deficits among 10 wheat ( Triticum aestivum L.) genotypes at maturation stage

Drought is a world-spread problem seriously influencing grain production and quality, the loss of which is the total for other natural disasters, with increasing global climate change making the situation more serious. Wheat is the staple food for more than 35% of world population, so wheat anti-drought physiology study is of importance to wheat production and biological breeding for the sake of coping with abiotic and biotic conditions. Much research is involved in this hot topic, but the pace of progress is not so large because of drought resistance being a multiple-gene-control quantitative character and wheat genome being larger (16,000 Mb). On the other hand, stress adaptive mechanisms are quite different, with stress degree, time course, materials, soil quality status and experimental plots, thus increasing the complexity of the issue in question. Additionally, a little study is related to the whole life circle of wheat, which cannot provide a comprehensive understanding of its anti-drought machinery. We selected 10 kinds of wheat genotypes as materials, which have potential to be applied in practice, and measured change of relative physiological indices through wheat whole growing-developmental circle (i.e. seedling, tillering and maturing). Here, we reported the anti-oxidative results of maturation stage (the results of seedling and tillering stage have been published) in terms of activities of POD, SOD, CAT and MDA content as follows: (1) 10 wheat genotypes can be grouped into three kinds (A–C, respectively) according to their changing trend of the measured indices; (2) A group performed better resistance drought under the condition of treatment level 1 (appropriate level), whose activities of anti-oxidative enzymes (POD, SOD, CAT) were higher and MDA lower; (3) B group exhibited stronger anti-drought under treatment level 2 (light-stress level), whose activities of anti-oxidative enzymes were higher and MDA lower; (4) C group expressed anti-drought to some extent under treatment level 3 (serious-stress level), whose activities of anti-oxidative enzymes were stronger, MDA lower; (5) these results demonstrated that different wheat genotypes have different physiological mechanisms to adapt themselves to changing drought stress, whose molecular basis is discrete gene expression profiling (transcriptom); (6) our results also showed that the concept and method accepted and adopted by most researchers [T.C. Hsiao, Plant response to water stress, Ann. Rev. Plant Physiol. 24 (1973) 519–570], that 75% FC is a proper supply for higher plants, was doubted, because this level could not reflect the true suitable level of different wheat genotypes. The study in this respect is the key to wheat anti-drought and biological-saving water agriculture; (7) our research can provide insights into physiological mechanisms of crop anti-drought and direct practical materials for wheat anti-drought breeding; (8) the physiological study of wheat is more urgent up-to-date and molecular aspects are needed, but cannot substitute this important part. The combination of both is an important strategy and a key and (9) POD, SOD and CAT activities and MDA content of different wheat genotypes had quite different changing trend at different stages and under different soil water stress conditions, which was linked with their origin of cultivation and individual soil water threshold.

Role of inducible nitric oxide synthase in cardiac function and remodeling in mice with heart failure due to myocardial infarction

Using inducible nitric oxide (NO) synthase (iNOS) knockout mice (iNOS-/-), we tested the hypotheses that 1) lack of iNOS attenuates cardiac remodeling and dysfunction and improves cardiac reserve postmyocardial infarction (MI), an effect that is partially mediated by reduction of oxidative stress due to reduced interaction between NO and reactive oxygen species (ROS); and 2) the cardioprotection afforded by iNOS deletion is eliminated by Nomega-nitro-L-arginine methyl ester (L-NAME) due to inhibition of endothelial NOS (eNOS) and neuronal NOS (nNOS). MI was induced by ligating the left anterior descending coronary artery. Male iNOS-/- mice and wild-type controls (WT, C57BL/6J) were divided into sham MI, MI+vehicle, and MI+l-NAME (100 mg.kg(-1).day(-1) in drinking water for 8 wk). Cardiac function was evaluated by echocardiography. Left ventricular (LV) maximum rate of rise of ventricular pressure divided by pressure at the moment such maximum occurs (dP/dt/instant pressure) in response to isoproterenol (100 ng.kg(-1).min(-1) iv) was measured with a Millar catheter. Collagen deposition, myocyte cross-sectional area, and expression of nitrotyrosine and 4-hydroxy-2-nonenal (4-HNE), markers for ROS, were determined by histopathological and immunohistochemical staining. We found that the MI-induced increase in LV chamber dimension and the decrease in ejection fraction, an index of systolic function, were less severe in iNOS-/- compared with WT mice. L-NAME worsened LV remodeling and dysfunction further, and these detrimental effects were also attenuated in iNOS-/- mice, associated with better preservation of cardiac function. Lack of iNOS also reduced nitrotyrosine and 4-HNE expression after MI, indicating reduced oxidative stress. We conclude that iNOS does not seem to be a pathological mediator of heart failure; however, the lack of iNOS improves cardiac reserve post-MI, particularly when constitutive NOS isoforms are blocked. Decreased oxidative stress and other adaptive mechanisms independent of NOS may be partially responsible for such an effect, which needs to be studied further.

Microbial inactivation by new technologies of food preservation

The increasing consumer demand for 'fresh-like' foods has led to much research effort in the last 20 years to develop new mild methods for food preservation. Nonthermal methods allow micro-organisms to be inactivated at sublethal temperatures thus better preserving the sensory, nutritional and functional properties of foods. The aim of this review is to provide an overview of the microbiological aspects of the most relevant nonthermal technologies for microbial inactivation currently under study, including irradiation, high hydrostatic pressure, pulsed electric field and ultrasound under pressure. Topics covered are the mechanisms of inactivation, sensitivity of different microbial groups and factors affecting it and kinetics of inactivation.

Dynamic changes of anti-oxidative enzymes of 10 wheat genotypes at soil water deficits

Drought is a world-spread problem seriously influencing crop production and quality, the loss of which is the total for other natural disasters, with increasing global climate change making the situation more serious. Wheat is the staple food for more than 35% of world population, so wheat anti-drought physiology study is of importance to wheat production and biological breeding for the sake of coping with abiotic and biotic conditions. Much research is involved in this hot topic, but the pace of progress is not so large because of drought resistance being a multiple-gene-control quantitative character and wheat genome being larger (16,000 Mb). On the other hand, stress adaptive mechanisms are quite different, with stress degree, different growth and developmental stages, time course, materials and experimental plots, thus increasing the complexity of the issue in question. Additionally, a little study is related to the whole life circle of wheat, which cannot provide a comprehensive understanding of its anti-drought machinery. We selected 10 kinds of wheat genotypes as materials, which have potential to be applied in practice, and measured change of relative physiological indices through wheat whole growing developmental circle (i.e. seedling, tillage and maturing). Here, we reported the dynamic anti-oxidative results of whole stage (i.e. seedling, tillage and maturing) in terms of activities of POD, SOD, CAT of 10 wheat genotypes as follows: (1) 10 wheat genotypes can be grouped into three kinds (A, B and C, respectively) according to their changing trend of the measured indices; (2) A group performed better resistance drought under the condition of treatment level 1, whose activities of anti-oxidative enzymes (POD, SOD, CAT) were higher; (3) B group exhibited stronger anti-drought under treatment level 2, whose activities of anti-oxidative enzymes were higher; (4) C group expressed anti-drought to some extent under treatment level 3, whose activities of anti-oxidative enzymes were stronger, MDA lower; (5) these results demonstrated that different wheat genotypes have different physiological mechanisms to adapt themselves to changing drought stress, whose molecular basis is discrete gene expression profiling (transcriptom); (6) our results also showed that the concept and method accepted and adopted by most researchers – that 75% FC is a proper supply for higher plants – was doubted because this level could not reflect the true suitable level of different wheat genotypes; (7) our research can provide insights into physiological mechanisms of crop anti-drought and direct practical materials for wheat anti-drought breeding; (8) POD, SOD and CAT activities of different wheat genotypes had quite different changing trend at different stages and under different soil water stress conditions, which was linked with their origin of cultivation and individual soil water stress threshold; (9) our primary results also firstly displayed that the changing trend for wheat adapting to environmental stress during life circle was an S-shaped curve, which is, by chance, consistent with Plant Growth Grand Periodicity Curve.

Changes of anti-oxidative enzymes and membrane peroxidation for soil water deficits among 10 wheat genotypes at seedling stage

Drought is one of the major factors limiting crop production globally, with increasing global climate change making the situation more serious. Wheat is the staple food for more than 35% of world population, so wheat anti-drought physiology study is of importance to wheat production and biological breeding for the sake of coping with abiotic and biotic conditions. Much research is involved in this hot topic, but the pace of progress is not so large because of drought resistance being a multiple-gene-control quantitative character and wheat genome being larger (16,000 Mb). On the other hand, stress adaptive mechanisms are quite different, with stress degree, time course, materials, and experimental plots, thus increasing the complexity of the issue in question. Additionally, a little study is related to the whole life circle of wheat, which cannot provide a comprehensive understanding of its anti-drought machinery. We selected 10 kinds of wheat genotypes as materials, which have potential to be applied in practice, and measured relative change of anti-oxidative enzymes and membrane peroxidation through wheat whole growth-developmental circle (i.e. seedling, tillering and maturing). Here, we firstly reported the results of seedling stage as follows: (1) 10 wheat genotypes can be grouped into three kinds (A–C, respectively) according to their changing trend of the measured indices; (2) A performed better resistance drought under the condition of treatment level 1 (appropriate level), whose activities of anti-oxidative enzymes (POD, SOD, CAT) were higher and MDA lower and chlorophyll a + b higher; (3) B exhibited stronger anti-drought under treatment level 2 (light stress level), whose activities of anti-oxidative enzymes were higher, MDA lower and chlorophyll higher; (4) C expressed anti-drought to some extent under treatment level 3 (serious stress), whose activities of anti-oxidative enzymes were stronger, MDA lower and chlorophyll higher; (5) these results demonstrated that different wheat genotypes have different physiological mechanisms to adapt themselves to changing drought stress, whose molecular basis is discrete gene expression profiling (transcriptom); (6) our results also showed that the concept accepted by most researchers, 70–75% QF [T.C. Hsiao, Plant responses to water stress, Ann. Rev. Plant Physiol. 24 (1973) 519–570] is a proper supply for plants, was doubted, because this level could not reflect the true suitable level of wheat. The study in this respect is the key to wheat anti-drought and biological saving-water; (7) our research can provide insights into physiological mechanisms of crop anti-drought and direct practical materials for wheat anti-drought breeding.