Defense response of a pepper cultivar cv. Sy-2 is induced at temperatures below 24°C

Temperature is one of the most important environmental factors that influence plant growth and development. Recent studies imply that plants show various responses to non-extreme ambient temperatures. Previously, we have found that a pepper cultivar cv. Sy-2 (Capsicum chinense) shows developmental defects at temperatures below 24°C. In this study, to gain new insights into the temperature sensitivity of cv. Sy-2, temperature-sensitive genes were screened using microarray techniques. At restrictive temperature of 20°C, almost one-fourth of the 411 up-regulated genes were defense related or predicted to be defense related. Further expression analyses of several defense-related genes showed that defense-related genes in cv. Sy-2 were constitutively expressed at temperatures below 24°C. Moreover, accumulation of high level of salicylic acid (SA) in cv. Sy-2 grown at 20°C suggests that the defense response is activated in the absence of pathogens. To confirm that the defense response is induced in cv. Sy-2 below 24°C, we evaluated the resistance to biotrophic bacterial pathogen Xanthomonas campestris pv. vesicatoria and necrotrophic fungal pathogen Cercospora capsici. Cv. Sy-2 showed enhanced resistance to X. campestris pv. vesicatoria, but not to C. capsici.     

Experimental forest soil warming: response of autotrophic and heterotrophic soil respiration to a short-term 10°C temperature rise

We warmed the top soil of a mature coniferous forest stand by means of heating cables on control and trenched plots within 24 h by 10°C at 1 cm soil depth (9°C at 5 cm depth) and measured the effect on the autotrophic (R_A) and heterotrophic (R_H) component of total soil CO₂ efflux (R_S). The short time frame of warming enabled us to exclude confounding fluctuations in soil moisture and carbon (C) flow from the canopy. The results of the field study were backed up by a lab soil incubation experiment. During the first 12 h of warming, R_A strongly responded to soil warming; The Q ₁₀ values were 5.61 and 6.29 for 1 and 5 cm soil depth temperature. The Q ₁₀ values for R_A were almost twice as high as the Q ₁₀ values of R_H (3.04 and 3.53). Q ₁₀ values above 5 are above reasonable plant physiological values for root respiration. We see interactions of roots, mycorrhizae and heterotrophic microbes, combined with fast substrate supply to the rhizosphere as an explanation for the high short-term temperature response of R_A. When calculated over the whole duration (24 h) of the field soil-warming experiment, temperature sensitivities of R_A and R_H were similar (no significant difference at P < 0.05); Q ₁₀ values were 3.16 and 3.96 for R_A and 2.94 and 3.35 for R_H calculated with soil temperatures at 1 and 5 cm soil depth, respectively. Laboratory incubation showed that different soil moisture contents of trenched and control plots affected rates of R_H, but did not affect the temperature sensitivity of R_H. We conclude that a single parameter is sufficient to describe the temperature sensitivity of R_S in soil C models which operate on larger temporal and spatial scales. The strong short-term response of R_A may be of relevance in soils suspected to experience increasingly strong diurnal temperature variations.     

Thermophilic bacteria that tolerate a wide temperature and pH range colonize the Soldhar (95 °C) and Ringigad (80 °C) hot springs of Uttarakhand,India

Twenty-eight bacterial cultures, isolated from hot springs in Uttarakhand, were characterized with particular reference to their wide temperature and pH tolerance and production of enzymes in the thermophilic range. All the bacterial isolates were observed as Gram-positive or variable rods in varied arrangement. Bacterial isolates exhibited tolerance to a wide temperature range (20–80 °C), from mesophilic (+11° to +45 °C) to thermophilic (+46 ° to +75 °C); few almost reached the hyperthermophilic range (+76 °C). The isolates also tolerated a wide pH range (4–14) and moderate salt concentration. The optimum growth of the bacterial isolates was observed at 55 °C and 7 pH. Out of 28 isolates, 25 produced lipase, 25 amylase, 24 cellulase, 22 protease and 13 xylanase at 55 and 65 °C. Tolerance to a wide temperature and pH range and the production of enzymes in a thermophilic temperature range can be considered as indicators of ecological competence of these bacterial isolates for colonizing the high temperature environment. On the basis of 16S rDNA similarity, 20 bacterial isolates belonged to Bacillus licheniformis, five to Paenibacillus ehimensis and one each to Bacillus sonorensis, B. tequilensis, and Staphylococcus epidermidis. Besides variation in phenotypic characters, strains of B. licheniformis and P. ehimensis showed varying 16S rDNA similarity between 97–99 % and 95–99 %, respectively. Consideration of temperature preferences in classifying microorganisms on the basis of their minimum, maximum, and optimum growth requirements is also discussed. The study has ecological relevance in the context of colonization of high temperature environments by thermophilic bacteria.     

Evidence from its temperature dependence that the β-dielectric dispersion of cell suspensions is not due solely to the charging of a static membrane capacitance

1. A survey of the literature indicates that the apparent capacitance per unit area (C _m ) of biological membranes is in general significantly greater than is that of artificial phospholipid (black lipid) membranes (BLM). It is not possible, by quantitative arguments alone, to exclude that this simply reflects the idea that protein-containing biological membranes have a greater thickness than BLM. 2. The temperature-dependence of the membrane capacitance for both solvent-containing and solvent-free BLM is negative. However, where appropriate data are available, it appears that the capacitance of biological membranes has a positive temperature-dependence, indicating a qualitative difference between natural and artificial membranes. 3. Using a 4-terminal dielectric spectrometer, and the fitting program and electrode polarisation correction described in the accompanying paper, we have carried out a careful study of the temperature-dependence of the -dielectric dispersion of a unicellular eukaryote (Saccharomyces cerevisiae) and a prokaryote (Escherichia coli). 4. In the range 15–40 °C, the temperature-dependence of the -dielectric dispersion (and thus in principle of C _m ) in S. cerevisiae and E. coli is respectively +0.13 and +0.35% (°C)^–1. 5. Flow cytometric measurements indicate that the cell size of E. coli is unchanged in the temperature range studied. 6. These data strongly suggest that the -dielectric dispersion in cell suspensions is not due solely to the charging of a static membrane capacitance. It is proposed that the positive temperature coefficient of the -dispersion reflects the contribution of temperature-dependent, partially restricted, lateral motions of the charged lipid and protein components of the cytoplasmic membrane. Offprint requests to: D. B. Kell     

Modification of the response of photosynthetic productivity to rising temperature by atmospheric CO2 concentrations: Has its importance been underestimated?

Abstract. Climate change will include correlated increases in temperature and atmospheric CO₂ concentration (C_a). Rising temperatures will increase the ratio of photorespiratory loss of carbon to photosynthetic gain, whilst rising C_a will have an opposing effect. The mechanism of these effects at the level of carboxylation in C₃ photosynthesis are quantitatively well understood and provide a basis for models of the response of leaf and canopy carbon exchange to climate change. The principles of such a model are referred to here and used to quantitatively examine the implications of concurrent increase in temperature and C_a. Simulations of leaf photosynthesis show the increase, with elevation of C_a from 350 to 650 μmol mol^-1, in light saturated rates of CO₂ uptake (A_sat) and maximum quantum yields (φ) to rise with temperature. An increase in C_a from 350 to 650 μmol mol^-1 can increase A_sat by 20% at 10°C and by 105% at 35°C, and can raise the temperature optimum of A_sat by 5°C. This pattern of change agrees closely with experimental data. At the canopy level, simulations also suggest a strong interaction of increased temperature and CO₂ concentration. Predictions are compared with the findings of long-term field studies. The principles used here suggest that elevated C_a will alter both the magnitude of the response of leaf and canopy carbon gain to rising temperature, and sometimes, the direction of response. Findings question the value of models for predicting plant production in response to climate change which ignore the direct effects of rising C_a and the modifications that rising C_a imposes on the temperature response of net CO₂ exchange.     

Break points in Arrhenius plots of the Hill reaction of spinach chloroplast fragments in the temperature range from -25 to 25?C

The relationship between temperature and 2,6-dichlorophenolindophenol(DPIP) photoreduction activity in chloroplast fragments isolatedfrom spinach grown at different temperatures was investigatedin the temperature range from –25 to 25?C. Two break points in the slope of the Arrhenius plot of the Hillreaction were observed at –9 and 11?C in chloroplast fragmentsisolated from spinach grown at low temperatures (0–10?C).These breaks were not affected by an uncoupler. In chloroplastfragments from spinach grown in a higher temperature range (10–30?C),only one break point was observed at –9?C. The other breakpoint at around 10?C appeared after treatment with detergent.Both break points were completely abolished by fixing the chloroplastfragments with glutaraldehyde. The break at around 10?C in chloroplast fragments isolated fromspinach grown at lower temperature was interpreted as due toacclimation rather than chilling sensitivity. (Received September 6, 1977; )     

Responses of cattle to the combined exposure to diurnal temperature rhythm (−5 to 25°C) and to simulated high-altitude (4,000 m)

Eight 1/2-year old calves were exposed in a climatized altitude chamber to the following four conditions: 400 and 4,000 m at constant T_a (17°C), 400 and 4,000 m at alternating T_a (–5° to 25°C). Each exposure lasted for 24 h and for the rhythmic conditions included a cold night and warm midday hours, supplemented by infrared heaters. During exposure, hourly measurements were made of heart rate, respiratory rate, rectal and three skin temperatures. Every 3-h blood samples were collected for the determination of 10 blood variables. The following main results were obtained: (a) Altitude alone caused increases in respiratory rate, heart rate, erythrocyte number, haemoglobin, specific gravity of blood and plasma, LDH and all four body temperatures. (b) In the rhythmic exposures, high correlation coefficients were found between ambient temperature on the one hand and skin temperatures (0.88 to 0.94), rectal temperature (–0.43) and respiratory rate (0.49) on the other hand. A change in ambient temperature by 1°C lead, on average, to a change in ear temperature by 1.2°C. (c) in response to falling ambient temperature during the night, rectal temperature and heart rate increased. This was interpreted as indicating a compensatory elevation in meta bolic heat production. At the same time, there was haemoconcentration as shown by elevations in erythrocyte number, haematocrit and haemoglobin. This haemoconcentration might have reflected splenic discharge, possibly supplemented by some loss of water from the plasma. (d) The warm environmental conditions around midday produced mild heat responses in terms of elevated values for respiratory rate, heart rate and body temperatures. (e) It is concluded that the rhythmic temperature with alternating stress of cold and mild heat, especially in combination with high altitude, was a strain on the animals and that they were forced to expend extra energy for combatting altitude- and temperature stress, energy which no longer would be available for productive processes.Presented at the Eight International Congress of Biometeorology, 9–14 September 1979, Shefayim, Israel.     

Diversity in the ability of Agaricus bisporus wild isolates to fruit at high temperature (25°C)

The button mushroom Agaricus bisporus commercially cultivated requires 16-19 °C during the fruiting period. Wild strains are also present in natural habitat, and in light of their wide range of geographic distribution reported, from boreal region to tropical region, questions on the development adaptation to temperature arose. Isolates from various geographic areas were screened for their ability to fruit at higher temperature (FHT ability) than commercial cultivars. The FHT trait discriminated at the varietal rank. Agaricus bisporus var. eurotetrasporus was unable to develop any sporophores whilst A. bisporus var. burnettii adapted perfectly to 25 °C for fruiting, suggesting that the FHT ability is a fixed trait in these varieties. In contrast, FHT ability of A. bisporus var. bisporus appeared variable and correlated neither with climate/microclimate nor with habitat. However, FHT ability taken as a whole appeared higher in North American populations than in European ones. Some A. bisporus var. bisporus isolates revealed a good potential for cultivation at 25 °C.     

Estimating the feeding range of a mobile consumer in a river-flood plain system using δ(13)C gradients and parasites

1.?The feeding range of an individual is central to food web dynamics as it determines the spatial scale of predator-prey interactions. However, despite recognition of its importance as a driving force in population dynamics, establishing feeding range is seldom done as detailed information on trophic interactions is difficult to obtain. 2.?Biological markers are useful to answer this challenge as long as spatial heterogeneity in signal is present within the area investigated. A spatially complex ecosystem, Lake St. Pierre (LSP), a fluvial lake of the St Lawrence River (Québec, Canada), offered a unique opportunity to determine the feeding range of a secondary consumer, yellow perch (Perca flavescens) using isotopic ratios of carbon (δ(13)C). However, because food chains based on phytoplankton have generally more negative δ(13) C than those depending on periphyton, it was essential to determine the contribution of zooplankton in fish diet to correctly interpret spatial patterns of δ(13)C. We used parasites in perch to examine whether their δ(13)C was reflecting local δ(13)C baseline conditions rather than a feeding specialization on zooplankton. 3.?δ(13)C of primary consumers was highly variable and exhibited a striking gradient along the shore-channel axis, suggesting that δ(13)C should reflect an individual consumer's spatial position in LSP. 4.?This strong isotopic gradient allowed us to estimate the spatial scale of the resources used by individual perch following an approach presented by Rasmussen, Trudeau & Morinville (Journal of Animal Ecology, 78, 2009, 674). By comparing the δ(13)C variability in perch to that of primary consumers, we estimated that the adults feeding range was around 2 km along the shore-channel axis. 5.?The combined use of isotopic ratios and parasites allowed us to determine that the adult population uses a wide range of habitats between the flood plain and the main channel. However, individually, each perch depended on a limited foodshed.     

Does the growth response of woody plants to elevated CO2 increase with temperature? A model‐oriented meta‐analysis

The temperature dependence of the reaction kinetics of the Rubisco enzyme implies that, at the level of a chloroplast, the response of photosynthesis to rising atmospheric CO₂ concentration (C_a) will increase with increasing air temperature. Vegetation models incorporating this interaction predict that the response of net primary productivity (NPP) to elevated CO₂ (eC_a) will increase with rising temperature and will be substantially larger in warm tropical forests than in cold boreal forests. We tested these model predictions against evidence from eC_a experiments by carrying out two meta‐analyses. Firstly, we tested for an interaction effect on growth responses in factorial eC_a × temperature experiments. This analysis showed a positive, but nonsignificant interaction effect (95% CI for above‐ground biomass response = ?0.8, 18.0%) between eC_a and temperature. Secondly, we tested field‐based eC_a experiments on woody plants across the globe for a relationship between the eC_a effect on plant biomass and mean annual temperature (MAT). This second analysis showed a positive but nonsignificant correlation between the eC_a response and MAT. The magnitude of the interactions between CO₂ and temperature found in both meta‐analyses were consistent with model predictions, even though both analyses gave nonsignificant results. Thus, we conclude that it is not possible to distinguish between the competing hypotheses of no interaction vs. an interaction based on Rubisco kinetics from the available experimental database. Experiments in a wider range of temperature zones are required. Until such experimental data are available, model predictions should aim to incorporate uncertainty about this interaction.     

Influence of IL28B polymorphisms on response to a lower-than-standard dose peg-IFN-α 2a for genotype 3 chronic hepatitis C in HIV-coinfected patients

Background

Data on which to base definitive recommendations on the doses and duration of therapy for genotype 3 HCV/HIV-coinfected patients are scarce. We evaluated the efficacy of a lower peginterferon-α 2a dose and a shorter duration of therapy than the current standard of care in genotype 3 HCV/HIV-coinfected patients.

Methods and Findings

Pilot, open-label, single arm clinical trial which involved 58 Caucasian HCV/HIV-coinfected patients who received weekly 135 µg peginterferon-α 2a plus ribavirin 400 mg twice daily during 20 weeks after attaining undetectable viremia. The relationships between baseline patient-related variables, including IL28B genotype, plasma HCV-RNA, ribavirin dose/kg, peginterferon-α 2a and ribavirin levels with virological responses were analyzed.Only 4 patients showed lack of response and 5 patients dropped out due to adverse events related to the study medication. Overall, sustained virologic response (SVR) rates were 58.3% by intention-to-treat and 71.4% by per protocol analysis, respectively. Among patients with rapid virologic response (RVR), SVR and relapses rates were 92.6% and 7.4%, respectively. No relationships were observed between viral responses and ribavirin dose/kg, peginterferon-α 2a concentrations, ribavirin levels or rs129679860 genotype.

Conclusions

Weekly 135 µg pegIFN-α 2a could be as effective as the standard 180 µg dose, with a very low incidence of severe adverse events. A 24-week treatment duration appears to be appropriate in patients achieving RVR, but extending treatment up to just 20 weeks beyond negativization of viremia is associated with a high relapse rate in those patients not achieving RVR. There was no influence of IL28B genotype on the virological responses.

Trial Registration:

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00553930","term_id":"NCT00553930"}}NCT00553930     

Acclimatory responses of the Daphnia pulex proteome to environmental changes. II. Chronic exposure to different temperatures (10 and 20°C) mainly affects protein metabolism

Background  

Temperature affects essentially every aspect of the biology of poikilothermic animals including the energy and mass budgets, activity, growth, and reproduction. While thermal effects in ecologically important groups such as daphnids have been intensively studied at the ecosystem level and at least partly at the organismic level, much less is known about the molecular mechanisms underlying the acclimation to different temperatures. By using 2D gel electrophoresis and mass spectrometry, the present study identified the major elements of the temperature-induced subset of the proteome from differently acclimated Daphnia pulex.     

Physiological tolerances of the euterrestrial amphipod Arcitalitrus dorrieni (Hunt) as a key to its geographical distribution? A test using mesocosms

An experimental approach was taken to examine the physiological tolerances that may determine the distribution of the euterrestrial amphipod Arcitalitrus dorrieni, a native of Australia which has established itself in the UK over the last 100 years. Two experiments using mesocosms were carried out over consecutive winters to examine the effects of low temperature and leaf litter sodium content on survival. The role of the microhabitat in buffering environmental temperature was also investigated. It was concluded that A. dorrieni may be prevented from colonising areas of Britain by the effects on populations of low winter temperatures and low habitat sodium concentration. There is considerable buffering of environmental temperatures by the leaf litter and soil layers of the microhabitat, and consequently, mortality of A. dorrieni is related to the depth of microhabitat available for it to utilise in avoiding low temperatures.     

Pyrolobus fumarii, gen. and sp. nov., represents a novel group of archaea, extending the upper temperature limit for life to 113°C

A novel, irregular, coccoid-shaped archaeum was isolated from a hydrothermally heated black smoker wall at the TAG site at the Mid Atlantic Ridge (depth 3650 meters). It grew at between 90°C and 113°C (optimum 106°C) and pH 4.0–6.5 (optimum 5.5) and 1%–4% salt (optimum 1.7%). The organism was a facultatively aerobic obligate chemolithoautotroph gaining energy by H₂-oxidation. Nitrate, S₂O₃ ^2–, and low concentrations of O₂ (up to 0.3% v/v) served as electron acceptors, yielding NH⁺ ₄, H₂S, and H₂O as end products, respectively. Growth was inhibited by acetate, pyruvate, glucose, starch, or sulfur. The new isolate was able to form colonies on plates (at 102°C) and to grow at a pressure of 25000 kPa (250 bar). Exponentially growing cultures survived a one-hour autoclaving at 121°C. The GC content was 53mol%. The core lipids consisted of glycerol–dialkyl glycerol tetraethers and traces of 2,3-di-O-phytanyl-sn-glycerol. The cell wall was composed of a surface layer of tetrameric protein complexes arranged on a p4-lattice (center-to-center distance 18.5nm). By its 16S rRNA sequence, the new isolate belonged to the Pyrodictiaceae. Based on its GC-content, DNA homology, S-layer composition, and metabolism, we describe here a new genus, which we name Pyrolobus (the "fire lobe"). The type species is Pyrolobus fumarii (type strain 1A; DSM). Received: 28 September 1996 / Accepted: 17 October 1996     

Induction of ?2 frameshift mutations within alternating GC sequences by carcinogens that bind to the C8 position of guanine residues Development of a specific mutation assay

Summary Using a forward mutation assay we have previously found that N-2-acetylaminofluorene (AAF), a strong chemical carcinogen, induces a majority of frameshift mutations located at specific sequences called mutation hot spots. Among these hot spot sequences, the NarI sequence (GGCGCC), is specific for –2 frameshifts (GGCGCC) GGCC). Interestingly, these frameshift mutations occur independently of a functional umuDC locus. Being interested in elucidating this mutation pathway we have developed a reversion assay that is specific for this class of mutations. The assay is based on the reversion of a +2 frameshift mutant of plasmid pBR322 from tetracycline sensitivity to tetracycline resistance. It is shown that only true reversion events lead to tetracycline resistance. The carcinogen AAF induces this reversion event at a frequency that is increased four- to fivefold over the background frequency. A series of chemical carcinogens which, like AAF, bind covalently to the C8 position of guanine, are compared for their efficiency to induce this specific mutation event. Large variations in the mutagenic efficiency of these chemicals are observed and discussed in terms of the anti/syn conformation of the carcinogen-modified guanine residue. Based on this test, we describe a convenient spot assay that this presently used in our laboratory to isolate Escherichia coli mutants affected in this mutation pathway.     

Inhibition of NADH oxidase activity and growth of HeLa cells by the antitumor sulfonylurea,N-(4-methylphenylsulfonyl)-N′-(4-chlorophenyl)urea (LY181984) and response to epidermal growth factor

Right side-out plasma membrane vesicles isolated from HeLa cells exhibited an NADH oxidase activity at their external surfaces that was inhibited by the antitumor sulfonylurea, N-(4-methylphenylsulfonyl)-N′-(4-chlorophenyl)urea (LY181984). Intact HeLa cells (fresh or frozen) also exhibited an NADH oxidase activity at the external cell surface. The inhibition of this activity by LY181984 was enhanced by the addition of epidermal growth factor (EGF). The order of addition was critical. It was necessary that the LY181984 be followed by the EGF. If the EGF was administered first, the response to LY181984 was unaffected by EGF. Binding of [³H]LY181984 to HeLa cells also was enhanced by EGF. Growth experiments with HeLa cells revealed a similar pattern of response to EGF. The EC₅₀ of growth inhibition of LY181984 was about 100 μM. However, if the LY181984 was followed by addition of 10 nM EGF, the EC₅₀ for LY181984 was reduced to about 30 nM which now approximated the previously determined K_d of [³H]LY181984 binding of 30 nM and the EC₅₀ of 30 nM for inhibition of NADH oxidase activity by LY181984 by isolated vesicles of plasma membranes. The tumor-inactive sulfonylurea N-(methylphenylsulfonyl-N′-(phenyl)urea (LY181985) was ineffective in the inhibition of NADH oxidation and of growth with HeLa cells either in the presence or absence of EGF.     

Site-directed <Emphasis Type="Italic">in vitro</Emphasis> immunization leads to a complete human monoclonal IgG4λ that binds specifically to the CDR2 region of CTLA-4 (CD152) without interfering the engagement of natural ligands

Background  

The ability to acquire fully human monoclonal antibodies (mAbs) with pre-defined specificities is critical to the development of molecular tags for the analysis of receptor function in addition to promising immunotherapeutics. Yet most of the arriving affinity maturated and complete human immunoglobulin G (IgG) molecules, which are actually derived from single human B cells, have not widely been used to study the conserved self antigens (Ags) such as CD152 (cytotoxic T lymphocyte antigen-4, CTLA-4) because proper hosts are lacking.