High Levels Of Na Research Articles

Maize (Zea Mays L.) Growth and Metabolic Dynamics with Plant Growth- Promoting Rhizobacteria under Salt Stress

Maize (Zea mays L.) biomass and its allied attributes were assessed under salinity stress and three plant growthpromoting rhizobacteria (Pseudomonas fluorescens, Pseudomonas putida and Azotobacter vinelandii) treatments. The three PGPRs inocula exhibited a different pattern of shoot growth under both normal and saline stress conditions. Plant biomass, carbohydrates, protein and chlorophyll content were reduced by saline stress, however application of PGPRs treatments improved them either in comparison to control samples or to untreated samples under saline stress. Lipids and antioxidant enzymes (catalase and peroxidase) increased as a response for saline stress as an indication of oxidative stress. Plant growth-promoting rhizobacteria treatment restored them to semi-normal levels. Sodium/ potassium balance was observed to be disturbed by saline stress through higher levels of Na+ and lower levels of K+, but treating samples balance was clearly restored close to normal conditions especially in the root system.

Coprodutos da agroindústria na alimentação de leitões

Foi realizado um experimento para determinar a composição química e digestibilidade dos nutrientes e energia do resíduo de batata palha (RBP), resíduo de pipoca doce (RPD), resíduo de biscoito de trigo doce (RBT), e resíduo de biscoito de trigo salgado (RBS) para leitões. Foram determinados os valores de matéria seca (MS), proteína bruta (PB), extrato etéreo (EE), matéria mineral (MM), cálcio (Ca), fósforo (P), sódio (Na) e energia bruta (EB). A digestibilidade dos alimentos foi avaliada utilizando 18 suínos alojados em gaiolas de metabolismo durante dois períodos consecutivos de 12 dias, sendo sete para adaptação e cinco destinados à coleta total de fezes. Os resultados de PB obtidos foram relativamente baixos, sendo 7,2; 6,0; 6,8 e 3,4% para o RBP, RPD, RBT e RBS, respectivamente. Os conteúdos de EE foram de 39,64; 7,12; 12,40; e 22,28% para o RBP, RPD, RBT e RBS, respectivamente. Os valores de Ca e P foram baixos e, em todos os coprodutos, inferiores a 0,18%. Teores elevados de Na foram encontrados no RBP e RBS (0,9 e 1,36%, respectivamente). A EB foi de 6.065; 4.199; 4.494; e 5.032 kcal kg-1 para RBP, RPD, RBT e RBS, respectivamente. Os valores de ED foram de 5.686; 3.995; 3.916 e 4.953 kcal kg-1, para RBP, RPD, RBT, e RBS e mostraram correlação linear e positiva (r2=0,97; P<0,05) com o teor de EE dos coprodutos. Estudos adicionais são necessários para estabelecer os teores ótimos de inclusão dos coprodutos analisados nas dietas de suínos. Contudo, os resultados de composição química e digestibilidade dos nutrientes e energia permitem concluir que os resíduos de batata palha, pipoca doce, biscoito de trigo doce e biscoito de trigo salgado possuem potencial para serem utilizados na alimentação de leitões.

Does reduced feeding prior to release improve the marine migration of hatchery brown trout Salmo trutta smolts?

The aim of this study was to test the hypothesis that hatchery brown trout Salmo trutta smolts, with 50% reduced or no feeding over the last 5 months before release, were more likely to migrate to the sea than individuals with standard feeding ratios. The juvenile fish were divided into three groups 176 days before release: (A) with no feeding, (B) with 50% and (C) with 100% feeding. To study their seaward migration, 40 fish from each feeding group were tagged with acoustic transmitters and tracked by automatic listening stations in the River Nidelva, Trondheim, Norway, its estuary and in the nearest marine environment. At the time of release, mean condition factor was significantly lower in group A and the fish from groups A and B had higher levels of Na+, K+-ATPase. Significantly more fish from group A migrated to the sea, but the rate of downstream progression from release to the estuary did not differ between the three groups. In conclusion, the S. trutta smolts with no access to food in the last 176 day before release were more likely to migrate to the sea. Fish from all three feeding groups, however, appeared to smoltify and had the same rate of downstream progression to the estuary. This indicates that differences in migratory behaviour between individuals from the three feeding groups begin from the time when the fish reach saline waters. It is suggested that feeding in hatcheries has to be greatly reduced (by 50% or more) over several months to have a pronounced effect on the migratory behaviour in S. trutta.

Saline and alkaline stress genotypic tolerance in sweet sorghum is linked to sodium distribution

Salt and alkali stress limit crop growth and reduce agricultural productivity worldwide, which have led to increased interest in enhancing salt tolerance in crop plants. Sweet sorghum (Sorghum bicolor (Linn.) Moench) is a monocotyledonous crop species that shows greater tolerance to salt–alkali stress than most other crops, although the underlying mechanisms behind this tolerance remain unclear. Therefore, we investigated the effects of salt and alkali stresses on two sweet sorghum varieties M-81E, which is stress tolerant, and 314B, which is stress sensitive. Namely, we surveyed plant growth parameters, measured Na+ and K+ distributions at the level of the whole plant as well as in three specific tissues, and then determined the activities of H+-ATPase, H+-PPase and Na+/H+ exchange in root vacuole membranes under stress conditions. Following treatment of the seedlings for 3 days with salt or alkali solutions, the plant growth was inhibited and Na+ levels in the whole plant, leaves, sheath, and roots were increased in both genotypes. Under alkali stress, K+ levels in the whole plant, leaves, sheath, and roots were decreased in both genotypes. M-81E roots accumulated significantly higher levels of Na+ than leaves, whereas the opposite was true for 314B. Under salt stress, both the hydrolytic and proton-transporting activities of V-H+-ATPase were enhanced and Na+/H+ exchange activity was dramatically upregulated, whereas V-H+-PPase activity was decreased. M-81E showed a greater capacity to compartmentalize Na+ within root cell vacuoles and maintain higher levels of K+ uptake compared with 314B, resulting in higher K+/Na+ transport selectivity in this genotype. These results also demonstrated that H+-ATPase activity and ionic homeostasis (Na+/K+) were likely important contributors to the tolerance of saline-alkali stress and crucially important for understanding alkaline stress in both crops and wild plants.

Application of Soil Composition for Inferring Fluoride Variability in Volcanic Areas of Mt. Meru, Tanzania

Predicting fluoride levels in water within fluoride endemic areas is an issue of high significance. As a result several methods including mathematical models have been reported to suit the task. However, most of these methods have limited practicality to low income communities. This study presents the potentials of employing soil characteristics to predict the level of fluoride in groundwater. The study is based at the areas around Mount Meru in Northern Tanzania. The volcanic sediments around this mountain had been segregated by geological studies into various lithologies. In this study water and soil samples were collected at springs in volcanic sediments categorized as main cone group, mantling ash, Tengeru lahar, Ongadongishu lahar and Ngarenanyuki lahar. Fluoride levels in water were then correlated to elemental composition of the soil. Water samples showed that fluoride was low in the main cone group, mantling ash and Tengeru lahar whereby the median concentration was 1mg/l but it was high in Ngarenanyuki and Ongadongishu lahars whereby the median concentrations were 4mg/l and 9mg/l respectively. Soil analyses indicated that high levels of aluminium do coincide along with low sodium levels, and vice versa. In addition high levels of sodium in soil are accompanied by high levels of calcium. Correlation studies indicated a strong negative relationship between aluminium in soil and fluoride in spring water with r2 = 0.847. On the other hand, a positive correlation was obtained between calcium in soil and fluoride in water with correlation coefficient, r2= 0.765. Likewise, sodium indicated a positive correlation with fluoride in water (r2= 0.458). So long as high levels of Na and Ca in soil or water normally result to formation of salts on the banks of water sources after prolonged evaporation during dry seasons, the correlation established between fluoride and such elements in soil can enable people within volcanic areas to identify water sources with unacceptable levels of fluoride in their areas hence reducing the risks of fluorosis.

ПОТРЕБНОСТЬ СУЯГНЫХ ОВЦЕМАТОК В НАТРИИ И ЕГО СОДЕРЖАНИЕ В ЖЕЛУДОЧНО-КИШЕЧНОМ ТРАКТЕ

The administration of mineral additive are ineffective and, moreover, harmful if not based on estimation of the real requirements of an animal with respect to biological effects of macroelements. In 3 years old Gissar sheep of 70 kg living mass («Raushan» individual farm, the Southern Kazakhstan) Na content in the chyme and gastrointestinal walls varied during the pregnancy. Na accumulation was high in small intestine, in which the intensive intake obviously occurred. A high Na level also was detected in paunch and large intestine. A total amount of Na in the paunch chyme was the highest during all pregnancy and exceeded the indexes in other probes up to 100 times. This data suggest that the walls of gastrointestinal tract are able to accumulate and to release Na depending on a physiological requirement.

Thermal Conversion of Cynara cardunculus L. and Mixtures with Eucalyptus globulus by Fluidized-Bed Combustion and Gasification

The behavior of Cynara cardunculus L. was studied during fluidized-bed (FB) combustion and gasification. The Cynara had a low moisture content and considerable lower heating value (LHV). Cynara presented significant quantities of S, Cl, and ash, which contained high levels of Na, K, P, Ca, and Si. The fuel N conversion to NOx was high because of the large release of NH3 and HCN during pyrolysis. The conversion of the fuel S to SO2 was low because of S retention mainly as alkali sulfates. HCl emissions were higher than the usual legal limits imposed in European Union (EU) countries, although retentions of 40–55% fuel Cl could be estimated. The co-combustion of Cynara with eucalyptus was tested with benefits regarding process conditions, pollutant emissions, and ash behavior, but still, the HCl concentration surpassed the legal limit. The tendency for bed agglomeration was also observed during the gasification of cardoon. Two strategies were carried out to minimize this adverse effect: (1) co-gasification o...

Sodium in plants: perception, signalling, and regulation of sodium fluxes

Although not essential for most plants, sodium (Na(+)) can be beneficial to plants in many conditions, particularly when potassium (K(+)) is deficient. As such it can be regarded a 'non-essential' or 'functional' nutrient. By contrast, the many salinized areas around the globe force plants to deal with toxicity from high levels of Na(+) in the environment and within tissues. Progress has been made in identifying the relevant membrane transporters involved in the uptake and distribution of Na(+). The latter is important in the context of mitigating salinity stress but also for the optimization of Na(+) as an abundantly available functional nutrient. In both cases plants are likely to require mechanism(s) to monitor Na(+) concentration, possibly in multiple compartments, to regulate gene expression and transport activities. Extremely little is known about whether such mechanisms are present and if so, how they operate, either at the cellular or the tissue level. This paper gives an overview of the regulatory and potential sensing mechanisms that pertain to Na(+), in both the context of salt stress and Na(+) as a nutrient.

Mineral and sensory profile of seasoned cracked olives packed in diverse salt mixtures

This work studies the effect of packing cracked seasoned olives with NaCl, KCl, and CaCl2 mixture brines on their mineral nutrients and sensory attributes, using RSM methodology. The Na, K, Ca, and residual natural Mn contents in flesh as well as saltiness, bitterness and fibrousness were significantly related to the initial concentrations of salts in the packing solution. This new process led to table olives with a significantly lower sodium content (about 31%) than the traditional product but fortified in K and Ca. High levels of Na and Ca in the flesh led to high scores of acidity and saltiness (the first descriptor) and bitterness (the second) while the K content was unrelated to any sensory descriptor. The new presentations using moderate proportions of alternative salts will therefore have improved nutritional value and healthier characteristics but only a slightly modified sensory profile.

Effect of Pasture or Maize Silage Feeding on the Nutritional Value of Beef

Effect of Pasture or Maize Silage Feeding on the Nutritional Value of BeefThe objective of this study was to evaluate the nutritional value of beef from different production systems. The study was conducted with Hereford bulls on organic and conventional farms. On the organic farm, fattening was mainly based on roughages, including pasture forage in the summer season, when the end of fattening occurred. On the conventional farm the bulls were fed maize silage and concentrate. On both farms, the animals were aged 7-9 months at the beginning of fattening. The bulls were fattened to a final body weight of 550-600 kg. Samples oflongissimus thoracismuscle were collected from half-carcasses of slaughtered bulls originating from each farm to analyse fat content, fatty acid profile, and content of selected minerals and vitamin E. Muscle samples were additionally analysed for the concentration of thiobarbituric acid-reactive substances 3 and 7 days after slaughter. Analyses showed a lower fat content inlongissimus thoracismuscle of bulls from the pasture feeding system. The fatty acid profile was also characterized by a lower content of C 14:0, and a higher content of polyunsaturated fatty acids (PUFA), including C18:3n-3, conjugated linoleic acid, C 20:5n-3, and C 22:5n-3, as well as by a lower ratio ofn-6/n-3 PUFA. The total content of monounsaturated fatty acids was significantly higher in animals fed maize silage and feed concentrate. In turn, the muscle of pasture fed animals had higher levels of Na, Zn and Fe as well as of vitamin E.

Content of selected elements in the muscle tissue of plaice (Pleuronectes platessa) and garfish (Belone belone) from the baltic sea

Fish are an important component of a balanced human diet. Marine fish are more popular than freshwater fish among Polish consumers. All fish are an excellent source of minerals, which the human body cannot synthesize. Hence, they should be provided with food in right amounts and proportions. However, fish can be contaminated by heavy metals. For this reason, it is very important to determine the levels of selected trace elements in fish. The aim of this study was to compare the content of mineral compounds in the muscle tissue of two species of fish from the Baltic Sea, i.e. plaice (Pleuronectes platessa) and garfish (Belone belone). Wet-digested fish muscle samples were used to analyze the content of macro(K, Na, Ca, Mg), and micronutrients (Zn, Fe, Mn, Cu) determined with flame atomic absorption spectrometry (AAS), and the levels of heavy metals (Cd, Pb) using flameless AAS. No significant differences between the species in the concentrations of K, Mg, Ca, Cu and heavy metals appeared, while the Na, Mn, Zn and Fe concentrations were significantly different between the two fish. Higher levels of Na, Mg, Mn and heavy metals were determined in muscle tissue of European plaice, while concentrations of the other macroand micronutrients were higher in muscles of garfish. The muscles of both species showed equal levels of Cd and Pb, below the maximum allowable limits.

A novel protein kinase involved in Na+ exclusion revealed from positional cloning

Salinity is a major abiotic stress which affects crop plants around the world, resulting in substantial loss of yield and millions of dollars of lost revenue. High levels of Na(+) in shoot tissue have many adverse effects and, crucially, yield in cereals is commonly inversely proportional to the extent of shoot Na(+) accumulation. We therefore need to identify genes, resistant plant cultivars and cellular processes that are involved in salinity tolerance, with the goal of introducing these factors into commercially available crops. Through the use of an Arabidopsis thaliana mapping population, we have identified a highly significant quantitative trait locus (QTL) linked to Na(+) exclusion. Fine mapping of this QTL identified a protein kinase (AtCIPK16), related to AtSOS2, that was significantly up-regulated under salt stress. Greater Na(+) exclusion was associated with significantly higher root expression of AtCIPK16, which is due to differences in the gene's promoter. Constitutive overexpression of the gene in Arabidopsis leads to plants with significant reduction in shoot Na(+) and greater salinity tolerance. amiRNA knock-downs of AtCIPK16 in Arabidopsis show a negative correlation between the expression levels of the gene and the amount of shoot Na(+) . Transgenic barley lines overexpressing AtCIPK16 show increased salinity tolerance.

EFFECT OF SOME VITAMINS ON THE IONIC BALANCE AND PROTEIN PROFILES OF SALT- STRESSED FLAX SEEDLINGS

The adverse effects of salinity on some physiological and biochemical responses of flax (Linum usitatissimum) seedlings grown at 100, 200, and 300 mM NaCl were studied. Salinity induced marked decreases in percentage of germination, reduction in nucleic acids, as well as membrane stability index (MSI) of salinized flax seedlings. Data also revealed that salinized flax seedlings accumulated high levels of Na, Cl, P and Mg while K and Ca ions were significantly decreased. Application of some vitamins (folic acid, ascorbic acid and cobalamin) counteracted the adverse effects of salinity. The mechanism of these vitamins on alleviating salt stress hazards might be mediated by stimulating the de novo synthesis of new set of low molecular weight proteins, reduction in some ions (Na and Cl) coupled with increases in the accumulation of others (K, Ca, P and Mg), consequently vitamins maintain high percentage of MSI throughout the experiment, thereby enhanced the capacity for germination under salt stress conditions.

Type D Personality, Self-Efficacy, and Medication Adherence Following an Acute Coronary Syndrome

To assess the relationship among Type D personality, self-efficacy, and medication adherence in patients with coronary heart disease. The study design was prospective and observational. Type D personality, self-efficacy for illness management behaviors, and medication adherence were measured 3 weeks after hospitalization for acute coronary syndrome in 165 patients (mean [standard deviation] age = 61.62 [10.61] years, 16% women). Self-reported medication adherence was measured 6 months later in 118 of these patients. Multiple linear regression and mediation analyses were used to address the study research questions. Using the original categorical classification, 30% of patients with acute coronary syndrome were classified as having Type D personality. Categorically defined patients with Type D personality had significantly poorer medication adherence at 6 months (r = -0.29, p < .01). Negative affectivity (NA; r = -0.25, p = .01) and social inhibition (r = -0.19, p = .04), the components of Type D personality, were associated with medication adherence 6 months after discharge in bivariate analyses. There was no evidence for the interaction of NA and social inhibition, that is, Type D personality, in the prediction of medication adherence 6 months after discharge in multivariate analysis. The observed association between NA and medication adherence 6 months after discharge could be partly explained by indirect effects through self-efficacy in mediation analysis (coefficient = -0.012; 95% bias-corrected and accelerated confidence interval = -0.036 to -0.001). The present data suggest the primacy of NA over the Type D personality construct in predicting medication adherence. Lower levels of self-efficacy may be a mediator between higher levels of NA and poor adherence to medication in patients with coronary heart disease.

Soil physicochemical properties and vegetation pattern in an arid environment affected by a salt diaper

Soil degradation, most notably caused by salinization and water-logging, creates formidable problems in arid and semi-arid environments. Advancing our knowledge of salt-affected soils is a prerequisite for understanding how salinization affects environmental concerns, such as soil erosion, nutrient leaching, and lack of vegetation cover. Therefore this study investigated the impact of salt diapirs on soil physicochemical conditions, as well as explored the relationship between halophytic vegetation and soil factors, and described the composition and distribution of plant species in relationship to soil salinity. The study area was divided into three units based on different geomorphologic conditions, slopes and vegetation type.Changes in salinity, soil properties and vegetation were studied. Results showed that the proportion of clay increased while silt and sand decreased with increasing distance from salt diapirs. The presence and kind of ions in all samples consistently indicated high levels of Na, and moderate levels of Mg, Ca, and K. Based on the soil conditions, plant covers were changed to types with more resistance to salinity and water-logging. Typically, this results in a decrease in soil structure stability through degradation of soil aggregates and a variation in the composition of the vegetation toward undesirable species. Key words: Salt diapirs, salinization, soil physicochemical properties, vegetation pattern, arid environment.

Extremely high salivary β2-microglobulin and Na+ levels in a Sjögren syndrome patient

Extremely high salivary β2-microglobulin and Na+ levels in a Sjögren syndrome patient

Physiological and molecular responses of two Arabidopsis accessions to calcium amendment and salt constraint

The Arabidopsis thaliana NOK2 accession displays salt tolerance compared to more commonly known A. thaliana accessions, such as Col-0, but the basis of this phenotypic feature is unknown. This work was focused on determining whether salt tolerance in NOK2 plants is affected by calcium supplementation to the growth medium. A. thaliana seedlings were grown in pots containing a mixture of sand and peat under controlled conditions in a low-level Ca(NO3)2 medium supplemented with 0 or 50 mM NaCl with and without amendment with two higher levels of Ca(NO3)2. Calcium amendment was beneficial for salt-treated NOK2 plants, as shown by the increase in dry weight of NOK2 plants with and without NaCl, but had no impact on Col-0 biomass. Sodium accumulation decreased as a function of calcium amendment in NOK2, while Col-0 maintained its high Na levels under these conditions. Leaf K+ content, K+ uptake, and Ca content decreased in NOK2 and Col-0 plants growing in the low-level Ca medium when NaCl was added, but rose in leaves of both accessions with calcium amendment, although K remained low in both accessions in the absence of NaCl. K+/Na+ selectivity increased preferentially in NOK2 with increasing calcium in the presence of NaCl, but when Na was restricted and not under any conditions in Col-0. Preferential effects of calcium were not observed on the transcript accumulation of seven Na+, K+ or Ca2+ transport genes for either of the accessions, except for increased transcription of the CAX4 gene in NOK2 leaves at the highest calcium concentration used (5 mM). Leaf membrane leakage, which increased two-fold higher in Col-0 under salt application compared with the increase in NOK2, declined for both accessions in response to calcium supplementation, and in NOK2 this decline reached no salt levels when Ca2+ amendments were highest. Chlorophyll and carotenoid content dropped two-fold in Col-0 in response to salt, but were unchanged in NOK2 under these conditions. In contrast, leaf anthocyanins, which were normally tenfold higher in Col-0 than in NOK2 in the low-level Ca2+ medium, declined in Col-0 plants as a function of Ca2+ supplementation, but were maintained at low levels in NOK2 leaves regardless of salinity and calcium. In conclusion, NOK2 plants responded positively to calcium supplementation by improving biomass yield during salinity treatment, whereas this amendment only affected Col-0 by reducing its permeability and anthocyanin titre. K+/Na+ selectivity appeared to be an important characteristic of NOK2 response to calcium. The regulation of this response may involve the CAX4 Ca2+/H+ vacuolar transport gene, but does not appear to involve six other common ion transporters.

Final results of a first-in-human phase I trial of PBI-05204, an inhibitor of AKT, FGF-2, NF-Kb, and p70S6K in advanced cancer patients.

3023 Background: PBI-05204 (Oleandrin), a cardiac glycoside, inhibits the α-3 subunit Na-K ATPase pump. Relative expression of the α-3 subunit in tumor cells correlates with proliferation. Oleandrin inhibits FGF-2 export, activation of NF-Kβ, phosphorylation of Akt, p70S6K, decreasing mTOR activity. In this first-in-human study, we sought to determine the MTD/recommended phase II dose and to define the pharmacokinetics (PK) and pharmacodynamics (PD) of PBI-05204 in advanced cancer patients (pts). Methods: Trial was a 3+3 phase I design. PBI-05240 was given for 21 of 28 days. Dose was increased by 100% if no related grade 2 adverse event (AE) emerged and increased by 50% if a grade 2 AE occurred. Blood samples were drawn for PK and drug-mediated changes in pAkt, p70S6K, and S6 (mTOR effectors) expression in peripheral blood mononuclear cells (PBMCs) for PD analysis. Results: 46 pts were dosed at 8 dose levels (DL) of PBI-05204 (0.6 to 10.2 mg/day). 2 dose-limiting toxicities occurred at DL 8 (grade 3 proteinuria,fatigue) thus the MTD was DL7. Most common AEs were fatigue (56.1%), abdominal pain (41.5%), constipation (41.5%), nausea (41.5%), and diarrhea (39.0%). Cardiac disorders were reported in 10 pts (24.4%), all grade 1, except for 1 pt with grade 2 SVT. Of the 45 evaluable pts, 7 had stable disease for > 4 months, with bladder, colorectal, fallopian tube, breast, appendecal and pancreatic carcinoma (2 pts). Dose dependent mean peak concentrations as high as 2 ng/mL were achieved. Mean AUC: 5 – 36 μg/L*hr across DLs with a half-life range of 6-14 hrs. Western blot analysis of PBMCs showed markedly reduced phosphorylation of Akt, p70S6K, and S6 in a time dependent manner in 7 pts (1 at DL 2, 3, 1 at DL 5 and 2 at DL 6). Reduction of these effectors was concomitant with higher levels of Na, K-ATPase aƒ{3 subunit expression. In these pts, results of proteomic array analysis showed other oncogenic pathways-NFkB, VEGF and STAT5 were down regulated after 21 days on study. Conclusions: PBI-05204 is well tolerated up to 10.2/mg/day with very little AEs or cardiotoxicity. Initial PD analysis suggesting target effect.

Characterization of the Periplasmic Region of PomB, a Na + -Driven Flagellar Stator Protein in Vibrio alginolyticus

The stator proteins PomA and PomB form a complex that couples Na(+) influx to torque generation in the polar flagellar motor of Vibrio alginolyticus. This stator complex is anchored to an appropriate place around the rotor through a putative peptidoglycan-binding (PGB) domain in the periplasmic region of PomB (PomB(C)). To investigate the function of PomB(C), a series of N-terminally-truncated and in-frame mutants with deletions between the transmembrane (TM) segment and the PGB domain of PomB was constructed. A PomB(C) fragment consisting of residues 135 to 315 (PomB(C₅) formed a stable homodimer and significantly inhibited the motility of wild-type cells when overexpressed in the periplasm. A fragment with an in-frame deletion (PomB(ΔL)) of up to 80 residues retained function, and its overexpression with PomA impaired cell growth. This inhibitory effect was suppressed by a mutation at the functionally critical Asp (D24N) in the TM segment of PomB, suggesting that a high level of Na(+) influx through the mutant stator causes the growth impairment. The overproduction of functional PomA/PomB(ΔL) stators also reduced the motile fractions of the cells. That effect could be slightly relieved by a mutation (L168P) in the putative N-terminal α-helix that connects to the PGB domain without affecting the growth inhibition, suggesting that a conformational change of the region including the PGB domain affects stator assembly. Our results reveal common features of the periplasmic region of PomB/MotB and demonstrate that a flexible linker that contains a "plug" segment is important for the control of Na(+) influx through the stator complex as well as for stator assembly.

Short communicationKey differences between school lunches and packed lunches in primary schools in England in 2009

To compare the key differences between school lunches and packed lunches as consumed in a nationally representative sample of primary schools, 6-8 months after the nutrient-based standards for school lunch became mandatory. Data on 6580 pupils' school lunches and 3422 pupils' packed lunches were collected between February and April 2009 from pupils attending primary schools in England. Fieldwork was conducted over five consecutive school days. Fieldworkers randomly selected ten pupils taking a school lunch and five pupils bringing a packed lunch each day at each school, and recorded and weighed all food and drink items consumed, as well as any leftovers. A nationally representative sample of 136 state-maintained primary schools in England. A total of 10 002 pupils aged 4-12 years. Mean intakes of protein, fat, saturated fat and vitamin C from both types of lunch met the nutrient-based standards. Pupils taking school lunches on average consumed significantly more protein, NSP, vitamin A, folate and Zn and less fat, saturated fat, non-milk extrinsic sugars (NMES), Na, Ca, vitamin C and Fe than pupils taking packed lunches. Energy intakes were low in both groups. Packed lunches were less likely to accord with food-based or nutrient-based standards than school lunches. Higher levels of Na, NMES, fat and percentage energy from saturated fat emphasise the difficulties associated with optimising nutrient intakes from packed lunches.