SAR in rats exposed in 2,450-MHz circularly polarized waveguides

Average specific absorption rates (SARs) for live rats exposed in 2,450-MHz circularly polarized waveguides were estimated from the total system loss determined from measurements using five power meters, and a correction factor representing actual SAR/apparent SAR. The actual SAR was measured by twin-well calorimetry and the apparent SAR by power meters. Values were obtained for carcasses of various body masses for five orientations. The average SAR with free movement in the cages changed less than threefold as the rats grew from 200 to 700 g. The ratio of peak to average SAR in the body was less than 3. These results indicate relatively constant energy disposition in rats exposed in the circularly polarized waveguide.     

Diversity and abundance of “Pelagibacterales” (SAR11) in the Baltic Sea salinity gradient

The candidate order “Pelagibacterales” (SAR11) is one of the most abundant bacterial orders in ocean surface waters and, periodically, in freshwater lakes. The presence of several stable phylogenetic lineages comprising “Pelagibacterales” correlates with the physico-chemical parameters in aquatic environments. A previous amplicon sequencing study covering the bacterial community in the salinity gradient of the Baltic Sea suggested that pelagibacteral subclade SAR11-I was replaced by SAR11-IIIa in the mesohaline region of the Baltic Sea. In this current study, we investigated the cellular abundances of “Pelagibacterales” subclades along the Baltic Sea salinity gradient using catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH). The results obtained with a newly designed probe, which exclusively detected SAR11-IIIa, were compared to CARD-FISH abundances of the marine SAR11-I/II subclade and the freshwater lineage SAR11-IIIb (LD12). The results showed that SAR11-IIIa was abundant in oligohaline–mesohaline conditions (salinities 2.7–13.3), with maximal abundances at a salinity of 7 (up to 35% of total Bacteria, quantified with a universal bacterial probe EUB). As expected, SAR11-I/II was abundant (27% of EUB) in the marine parts of the Baltic Sea, whereas counts of the freshwater lineage SAR11-IIIb were below the detection limit at all stations. The shift from SAR11-IIIa to SAR11-I/II was confirmed in the vertical salinity gradient in the deeper basins of the Baltic Sea. These findings were consistent with an overlapping but defined distribution of SAR11-I/II and SAR11-IIIa in the salinity gradient of the Baltic Sea and suggested the adaptation of SAR11-IIIa for growth and survival in mesohaline conditions.     

Systemic acquired resistance signal transduction

Systemic acquired resistance (SAR) is an inducible plant defense response in which a prior foliar pathogen infection activates resistance in noninfected foliar tissues. Salicylic acid (SA) accumulation is essential for the establishment of SAR. While SA is probably not the long‐distance systemic signal instrumental for SAR activation, it is required for transduction of the signal in noninfected tissues. Although SAR was first described as a response to necrogenic pathogen infection, synthetic chemicals have been identified that effectively activate SAR. Elucidation of SAR signal transduction has been facilitated by the identification and characterization of Arabidopsis mutants. Disease lesion mimic mutants exhibit constitutive SAR as well as spontaneous lesion formation similar to pathogen‐associated hypersensitive cell death. Some disease lesion mimic mutants do not exhibit a lesioned phenotype when SA accumulation is prevented, thereby providing evidence for a feedback loop in SAR signal transduction. Moreover, characterization of mutants compromised for SAR activation has provided additional evidence for common signaling components between SAR and gene‐for‐gene resistance.     

Volume-averaged SAR in adult and child head models when using mobile phones: a computational study with detailed CAD-based models of commercial mobile phones

Previous studies comparing SAR difference in the head of children and adults used highly simplified generic models or half-wave dipole antennas. The objective of this study was to investigate the SAR difference in the head of children and adults using realistic EMF sources based on CAD models of commercial mobile phones. Four MRI-based head phantoms were used in the study. CAD models of Nokia 8310 and 6630 mobile phones were used as exposure sources. Commercially available FDTD software was used for the SAR calculations. SAR values were simulated at frequencies 900 MHz and 1747 MHz for Nokia 8310, and 900 MHz, 1747 MHz and 1950 MHz for Nokia 6630. The main finding of this study was that the SAR distribution/variation in the head models highly depends on the structure of the antenna and phone model, which suggests that the type of the exposure source is the main parameter in EMF exposure studies to be focused on. Although the previous findings regarding significant role of the anatomy of the head, phone position, frequency, local tissue inhomogeneity and tissue composition specifically in the exposed area on SAR difference were confirmed, the SAR values and SAR distributions caused by generic source models cannot be extrapolated to the real device exposures. The general conclusion is that from a volume averaged SAR point of view, no systematic differences between child and adult heads were found.     

Systemic Acquired Resistance to Virus Infections and Ethylene Biosynthesis in Asparagus Bean

Systemic acquired resistance (SAR) was induced in asparagus bean following inoculation with tobacco necrosis virus (TNV) or tobacco rattle virus (TRV), viruses that produce a hypersensitive reaction in this plant. SAR was expressed against challenge by TNV as reduction in lesion size, but not as inhibition of viral antigen accumulation. Systemic stimulation of ethylene-forming enzyme (EFA) activity, in the absence of any ethylene increase or 1-aminocyclopropane-1-carboxylic acid (ACC) accumulation, was associated with SAR. Formation of local necrotic lesions was necessary for both induction of SAR and stimulation of EFA, because early removal of inducer leaves prevented both events. SAR was expressed at rather constant level between 7 and 12 days after inducing infection. EFA stimulation declined with time and was no longer detected 7 days after inducing infection. SAR was not expressed against cucumber mosaic virus, that infect asparagus bean systemically. Prior inoculation with TNV or TRV was ineffective to reduce CMV antigen content or to minimize the pathogenic effect of this virus in systemically infected leaves.     

Dosimetry evaluation of a cylindrical waveguide chamber for unrestrained small rodents at 1.9 GHz

An exposure system, consisting of four identical cylindrical waveguide chambers, was developed for studying the effects of radiofrequency (RF) energy on laboratory mice at a frequency of 1.9 GHz. The chamber was characterized for RF dose rate as a function of animal body mass and dose rate variations due to animal movement in the cage. Dose rates were quantified in terms of whole‐body average (WBA) specific absorption rate (SAR), brain average (BA) SAR and peak spatial‐average (PSA) SAR using measurement and computational methods. Measurements were conducted on mouse cadavers in a multitude of possible postures and positions to evaluate the variations of WBA‐SAR and its upper and lower bounds, while computations utilizing the finite‐difference time‐domain method together with a heterogeneous mouse model were performed to determine variations in BA‐SAR and the ratio of PSA‐SAR to WBA‐SAR. Measured WBA‐SAR variations were found to be within the ranges of 9–23.5 W/kg and 5.2–13.8 W/kg per 1 W incident power for 20 and 40 g mice, respectively. Computed BA‐SAR variations were within the ranges of 3.2–10.1 W/kg and 3.3–9.2 W/kg per 1 W incident power for 25 and 30 g mouse models, respectively. Ratios of PSA‐SAR to WBA‐SAR, averaged over 0.5 mg and 5 mg tissue volumes, were observed to be within the ranges of 6–15 and 4–10, respectively. Bioelectromagnetics 33:575–584, 2012. © 2012 Wiley Periodicals, Inc.     

Fitness benefits of systemic acquired resistance during Hyaloperonospora parasitica infection in Arabidopsis thaliana

We investigated the fitness benefits of systemic acquired resistance (SAR) in Arabidopsis thaliana using a mutational and transformational genetic approach. Genetic lines were designed to differ in the genes determining resistance signaling in a common genetic background. Two mutant lines (cpr1 and cpr5) constitutively activate SAR at different points in SAR signaling, and one mutant line (npr1) has impaired SAR. The transgenic line (NPR1-H) has enhanced resistance when SAR is activated, but SAR is still inducible similarly to wild type. The fitness benefits were also investigated under two nutrient levels to test theories that preventing pathogen damage and realized resistance benefits may be affected by nutrient availability. Under low-nutrient conditions and treatment with the pathogenic oomycete, Hyaloperonospora parasitica, wild type had a higher fitness than the mutant that could not activate SAR, demonstrating that normal inducible SAR is beneficial in these conditions; this result, however, was not found under high-nutrient conditions. The mutants with constitutive SAR all failed to show a fitness benefit in comparison to wild type under a H. parasitica pathogen treatment, suggesting that SAR is induced to prevent an excessive fitness cost.     

Effects of ouabain and flecainide on CO(2)-induced slowly adapting pulmonary stretch receptor inhibition in the rabbit

The inhibitory effect of CO2 on slowly adapting pulmonary stretch receptors (SARs) was examined before and after administration of ouabain, a Na+-K+ ATPase inhibitor, and flecainide, a Na+ channel blocker. The experiments were performed in anesthetized, artificially ventilated rabbits after vagus nerve section. CO2 inhalation (maximal tracheal CO2 concentration ranging from 9.2 % to 10.4%) for about 60 sec decreased the receptor activity during both inflation and deflation. The magnitude of decreased SAR activity during deflation was greater than that seen during inflation. Administration of ouabain (25 microg/kg) initially stimulated SAR activities during inflation and deflation, and after 20 min, the SAR response was still kept excitatory in both inflation and deflation phases. Under these conditions, CO2 inhalation inhibited SAR activities during inflation and deflation. Flecainide treatment (3 mg/kg) that abolished veratridine (30 microg/kg)-induced SAR excitation had no significant effect on the inhibitory responses of SAR activity to CO2. These results suggest that the inhibitory effect of CO2 occurs when ouabain results in intracellular Na+ concentration ([Na+]i) increases in the SAR endings, and that CO2-induced SAR inhibition may not be related to the reduction of influx of Na+ through voltage-gated Na+ channels.     

A comparison of sucrose,saline, and saline with egg-yolk diluents on the cryopreservation of cane toad (Bufo marinus) sperm

Previous studies on cane toad (Bufo marinus; Bufonidae; Anura) sperm cryopreservation were extended to compare the effects of cryopreservation in established sucrose (non-ionic) diluents with cryopreservation in ionic diluents containing amphibian Ringer solutions (with and without egg-yolk). In addition, methanol was tested as a cryoprotectant for B. marinus sperm for the first time. Twenty-seven cryoprotective solutions were trialled, with each containing one of the three diluents [10% (w/v) sucrose, simplified amphibian Ringer (SAR) or SAR/egg-yolk], with one of the three cryoprotectants (Me(2)SO, glycerol, or methanol) at one of the three concentrations (10%, 15%, or 20% v/v). Sperm were collected by maceration of testes into cryoprotective solutions with post-thaw recovery assessed as the percentage of motile sperm and the degree (vigour) of motility. Percentage motility was the most sensitive measure of post-thaw recovery. The recovery of motility was lowest in Ringer (SAR) diluents and highest in sucrose diluents, with improved motility in SAR diluents when egg-yolk was added. Methanol was the poorest cryoprotectant and Me(2)SO the most effective. Methanol at high concentrations was shown to support recovery in sucrose diluent but not in SAR, although its effectiveness in SAR was improved by egg-yolk. Overall, the efficacy of diluents in supporting a high percentage of sperm recovery was in declining order: sucrose>SAR/egg-yolk>SAR diluents, and with cryoprotectants: Me(2)SO>glycerol>methanol. In conclusion, SAR offers less potential as a diluent than sucrose, presumably due to the presence of inorganic ions.     

Contribution of SAR11 bacteria to dissolved dimethylsulfoniopropionate and amino acid uptake in the North Atlantic ocean

SAR11 bacteria are abundant in marine environments, often accounting for 35% of total prokaryotes in the surface ocean, but little is known about their involvement in marine biogeochemical cycles. Previous studies reported that SAR11 bacteria are very small and potentially have few ribosomes, indicating that SAR11 bacteria could have low metabolic activities and could play a smaller role in the flux of dissolved organic matter than suggested by their abundance. To determine the ecological activity of SAR11 bacteria, we used a combination of microautoradiography and fluorescence in situ hybridization (Micro-FISH) to measure assimilation of (3)H-amino acids and [(35)S]dimethylsulfoniopropionate (DMSP) by SAR11 bacteria in the coastal North Atlantic Ocean and the Sargasso Sea. We found that SAR11 bacteria were often abundant in surface waters, accounting for 25% of all prokaryotes on average. SAR11 bacteria were typically as large as, if not larger than, other prokaryotes. Additionally, more than half of SAR11 bacteria assimilated dissolved amino acids and DMSP, whereas about 40% of other prokaryotes assimilated these compounds. Due to their high abundance and activity, SAR11 bacteria were responsible for about 50% of amino acid assimilation and 30% of DMSP assimilation in surface waters. The contribution of SAR11 bacteria to amino acid assimilation was greater than would be expected based on their overall abundance, implying that SAR11 bacteria outcompete other prokaryotes for these labile compounds. These data suggest that SAR11 bacteria are highly active and play a significant role in C, N, and S cycling in the ocean.     

Contribution of SAR11 Bacteria to Dissolved Dimethylsulfoniopropionate and Amino Acid Uptake in the North Atlantic Ocean

SAR11 bacteria are abundant in marine environments, often accounting for 35% of total prokaryotes in the surface ocean, but little is known about their involvement in marine biogeochemical cycles. Previous studies reported that SAR11 bacteria are very small and potentially have few ribosomes, indicating that SAR11 bacteria could have low metabolic activities and could play a smaller role in the flux of dissolved organic matter than suggested by their abundance. To determine the ecological activity of SAR11 bacteria, we used a combination of microautoradiography and fluorescence in situ hybridization (Micro-FISH) to measure assimilation of ³H-amino acids and [³⁵S]dimethylsulfoniopropionate (DMSP) by SAR11 bacteria in the coastal North Atlantic Ocean and the Sargasso Sea. We found that SAR11 bacteria were often abundant in surface waters, accounting for 25% of all prokaryotes on average. SAR11 bacteria were typically as large as, if not larger than, other prokaryotes. Additionally, more than half of SAR11 bacteria assimilated dissolved amino acids and DMSP, whereas about 40% of other prokaryotes assimilated these compounds. Due to their high abundance and activity, SAR11 bacteria were responsible for about 50% of amino acid assimilation and 30% of DMSP assimilation in surface waters. The contribution of SAR11 bacteria to amino acid assimilation was greater than would be expected based on their overall abundance, implying that SAR11 bacteria outcompete other prokaryotes for these labile compounds. These data suggest that SAR11 bacteria are highly active and play a significant role in C, N, and S cycling in the ocean.     

The extent to which methyl salicylate is required for signaling systemic acquired resistance is dependent on exposure to light after infection

Systemic acquired resistance (SAR) is a state of heightened defense to a broad spectrum of pathogens that is activated throughout a plant following local infection. Development of SAR requires the translocation of one or more mobile signals from the site of infection through the vascular system to distal (systemic) tissues. The first such signal identified was methyl salicylate (MeSA) in tobacco (Nicotiana tabacum). Subsequent studies demonstrated that MeSA also serves as a SAR signal in Arabidopsis (Arabidopsis thaliana) and potato (Solanum tuberosum). By contrast, another study suggested that MeSA is not required for SAR in Arabidopsis and raised questions regarding its signaling role in tobacco. Differences in experimental design, including the developmental age of the plants, the light intensity, and/or the strain of bacterial pathogen, were proposed to explain these conflicting results. Here, we demonstrate that the length of light exposure that plants receive after the primary infection determines the extent to which MeSA is required for SAR signaling. When the primary infection occurred late in the day and as a result infected plants received very little light exposure before entering the night/dark period, MeSA and its metabolizing enzymes were essential for SAR development. In contrast, when infection was done in the morning followed by 3.5 h or more of exposure to light, SAR developed in the absence of MeSA. However, MeSA was generally required for optimal SAR development. In addition to resolving the conflicting results concerning MeSA and SAR, this study underscores the importance of environmental factors on the plant's response to infection.     

Energy deposition in a model of man in the near field

The spatial distribution of the specific absorption rate (SAR) was measured in a full-scale model of man using implantable electric field probes. The model was exposed in the near-field of linear and aperture antennas at 350 MHz. Effects of the wave polarization, antenna position and antenna gain on the SAR distribution and the average SAR in the whole-body and body parts are reported.     

Antiplatelet therapy mitigates cardiac remodeling and dysfunction in congestive heart failure due to myocardial infarction

Antiplatelet agents such as sarpogrelate (SAR), a 5-hydroxytryptamine antagonist, and cilostazol (CIL), a phosphodiesterase-III inhibitor, are used in the management of peripheral vascular disease. In this study, we tested the hypothesis that both SAR and CIL prevent cardiac remodeling and improve cardiac function in congestive heart failure (CHF) due to myocardial infarction (MI). Post-MI rats (3 weeks after the occlusion of coronary artery) received either vehicle (MI+V, n = 36), SAR (MI+SAR; 5 mg xc kg(-1) x day(-1), n = 35) or CIL (MI+CIL; 5 mg x kg(-1) x day(-1), n = 34) from day 21 to day 56. Sham-operated rats (n = 29) served as controls. Electrocardiographic, echocardiographic, and hemodynamic parameters were measured on day 56. Treatment of infarcted animals with SAR or CIL significantly improved the left ventricular (LV) dimensions, LV fractional shortening, cardiac output, stroke volume, mean arterial pressure, LV diastolic function, and LV systolic pressure, as well as rates of LV pressure development and pressure decay. Although cardiac hypertrophy was reduced, both SAR and CIL had no effect on infarct size or MI-associated QTc prolongation. However, SAR decreased whereas CIL increased the incidence of ventricular arrhythmias and the mean number of episodes in infarcted animals. Mortality during the treatment period was decreased by 17% with SAR and increased by 10% with CIL, but these changes were not significant statistically. The data in this study suggest that both SAR and CIL prevent cardiac remodeling and improve cardiac function in MI-induced CHF; however, CIL unlike SAR increased the incidence of arrhythmias and adversely affected patient mortality.     

Abscisic acid modulates salicylic acid biosynthesis for systemic acquired resistance in tomato

Among the regulatory mechanisms of systemic acquired resistance (SAR) in tomato, antagonistic interaction between salicylic acid (SA) and abscisic acid (ABA) signaling pathways was investigated. Treatment with 1,2-benzisothiazol-3(2H)-one1,1-dioxide (BIT) induced SAR in tomato thorough SA biosynthesis. Pretreatment of ABA suppressed BIT-induced SAR including SA accumulation, suggesting that ABA suppressed SAR by inhibiting SA biosynthesis.     

Abundance and activity of Chloroflexi-type SAR202 bacterioplankton in the meso- and bathypelagic waters of the (sub)tropical Atlantic

The contribution of Chloroflexi-type SAR202 cells to total picoplankton and bacterial abundance and uptake of D- and L-aspartic acids (Asp) was determined in the different meso- and bathypelagic water masses of the (sub)tropical Atlantic (from 35 degrees N to 5 degrees S). Fluorescence in situ hybridization (FISH) revealed that the overall abundance of SAR202 was < or = 1 x 10(3) cells ml(-1) in subsurface waters (100 m layer), increasing in the mesopelagic zone to 3 x 10(3) cells ml(-1) and remaining fairly constant down to 4000 m depth. Overall, the percentage of total picoplankton identified as SAR202 increased from < 1% in subsurface waters to 10-20% in the bathypelagic waters. On average, members of the SAR202 cluster accounted for about 30% of the Bacteria in the bathypelagic waters, whereas in the mesopelagic and subsurface waters, SAR202 cells contributed < 5% to total bacterial abundance. The ratio of D-Asp : L-Asp uptake by the bulk picoplankton community increased from the subsurface layer (D-Asp : L-Asp uptake ratio approximately 0.03) to the deeper layers reaching a ratio of approximately 1 at 4000 m depth. Combining FISH with microautoradiography to determine the proportion of SAR202 cells taking up D-Asp versus L-Asp, we found that approximately 30% of the SAR202 cells were taking up L-Asp throughout the water column while D-Asp was essentially not taken up by SAR202. This D-Asp : L-Asp uptake pattern of SAR202 cells is in contrast to that of the bulk bacterial and crenarchaeal community in the bathypelagic ocean, both sustaining a higher fraction of D-Asp-positive cells than L-Asp-positive cells. Thus, although the Chloroflexi-type SAR202 constitutes a major bathypelagic bacterial cluster, it does not contribute to the large fraction of d-Asp utilizing prokaryotic community in the meso- and bathypelagic waters of the North Atlantic, but rather utilizes preferentially L-amino acids.     

Magnetic resonance imaging: calculation of rates of energy absorption by a human-torso model

The three-dimensional impedance method was used to estimate specific absorption rate (SAR) in a human-torso model during exposure to the time-varying and static magnetic fields used in magnetic resonance imaging (MRI). Analytical data for discrete tissues as well as the entire torso are presented. Generalized equations were derived that enable calculation of whole-torso SAR over a broad range of conditions. In addition, the impedance method can generate data about internal distributions of SAR, which are needed to predict critical organs that might undergo excessive elevations of temperature. Fair to good agreement was found between impedance-method SAR and those predicted by simple phenomenological models.     

Compatibility of systemic acquired resistance and microbial biocontrol for suppression of plant disease in a laboratory assay

Systemic acquired resistance (SAR) and microbial biocontrol each hold promise as alternatives to pesticides for control of plant diseases. SAR and Bacillus cereus UW85, a microbial biocontrol agent, separately suppress seedling damping-off diseases caused by oomycete pathogens. The purposes of this study were to investigate how expression of SAR affected the efficacy of biocontrol by UW85 and if UW85 treatment of plants induced SAR. We devised a laboratory assay in which seedling damping-off disease, induction of SAR, and growth of UW85 could be quantified. Seedlings of Nicotiana tabacum Xanthi nc were germinated on moist filter paper and transferred after 7 days to water agar plates (40 seedlings per plate). Zoospores of oomycete pathogens (Pythium torulosum, Pythium aphanidermatum, or Phytophthora parasitica) were applied at concentrations that caused 80% seedling mortality within 10 days. Seedling mortality was dependent on zoospore inoculum concentration. The level of disease suppression caused by treatment with UW85 depended on the UW85 dose applied. SAR was induced with 0.5-mM salicylic acid or 0.1-mM 2,6-dichloroisonicotinic acid. Expression of an SAR-related gene was confirmed by northern analysis with a probe prepared from a tobacco PR-1a cDNA. Induction of SAR suppressed disease caused by each of the oomycete pathogens, but did not alter the growth of UW85 on roots. Treatment of seedlings with UW85 did not induce the expression of PR-1a. The combination of induction of SAR and treatment with UW85 resulted in additive suppression of disease as measured by seedling survival.