A study of salt tolerance in Arabidopsis thaliana and Hordeum vulgare

ABSTRACT The original objective of this work was to compare the cellular processes in salt tolerant and salt sensitive plants cells to gain insight into the mechanisms that confer halotolerance. Halotolerant and salt sensitive cell lines were derived from the model glycophyte Arabidopsis thaliana; in addition cell suspension cultures from the dicot halophytes Beta vulgaris and Atriplex halimus were also generated. Unfortunately, severe disruptions were encountered following a serious fire; persistent power failures, and failures of new equipment hampered progress with this work. For this reason, only comparisons between the Arabidopsis cell lines were completed. The halotolerant (HHS) cell lines survival strategy is to prevent Na accumulation when grown in < 100 mM NaCl. Wild type (WT) cells grow faster than HHS cells in the absence of NaCl, but rapidly take up Na in 50 mM NaCl where their growth is severely affected, and fail to grow completely above 100 mM NaCl. No evidence was found to suggest this growth impairment arose from osmotic stress or nutrient ion deficiencies. Protein profiling of HHS cells identified a number of proteins whose abundance is regulated by salt stress. These included proteins involved in ion transport, central metabolism, and general stress responses. The implications of these findings are discussed. In a separate project, a whole plant approach was taken to establish the physiological mechanisms that account for the reported difference in halotolerance between two commercially grown barley lines originating from China. Measurements on growth and development, plant water status, tissue ion profiling, photosynthesis rates, and transpiration rates suggested the tolerant line (Zhou 1) enters the reproductive phase of its life cycle approximately one week earlier than the sensitive line (Zhou 85), and this critical period allows floral development resulting in improved yields. This early ii flowering is not associated with the well characterized PpD-H1 locus controlling early flowering in cereals. The main conclusion from this study is that for glycophytes that do not complete a full life cycle above 100 mM NaCl (which includes all of the world’s major crops), it is the ionic component of salinity stress that impairs growth and yield. Further research on salinity stress in crops should focus on understanding the processes that control ionic balance rather than osmoregulation

Influence of Lipophilicity on the Accumulation and Distribution of Halogenated Phenols and a Pyridinol as Metabolites of Pesticides in the Rat

Exposure to halogenated phenols and pyridinols is of increasing concern because of their wide use and distribution. This research was initiated to determine the distribution, accumulation, and depletion of a group of halogenated phenols and a pyridinol in selected tissues of male weanling rats at different time intervals following a single oral dose of 0.33 or 1.66 m moles per kg body weight. The halogenated phenols and pyridinol were distributed differently in every tissue sampled following their administration, even though the amount administered was the same in each case. The concentrations in tissue were found in the order: 2,4,5-trichloro-phenol \u3e 4-bromo-2,5-dichlorophenol \u3e 4-iodo-2,5-dichlorophenol \u3e 3,5,6-trichloro-2-pyridonol in kidney and fat, whereas the series 3,5,6-trichloro-2-pyridinol \u3e 4-iodo-2,5-dichlorophenol \u3e 4-bromo-2,5-dichlorophenol \u3e 3,5,6-trichlorophenol occurred in liver. No structurally significant series was observed for their concentrations in blood. All halogenated phenols and pyridinol concentrations in tissues declined rapidly with time but not always in an apparently log linear fashion. Rates were greatest for clearance from blood. The highest concentration of halogenated phenols was in kidney among the tissues studied, whereas the highest concentration of halogenated pyridinol was in liver. Relationships were found between the relative lipophilicity, as indicated by the chromatographic Rm value, and the concentrations of these compounds in tissues. The RH (i.e., relative lipophilicity) was generally very well correlated with the log concentration of compounds in tissues observed 24 h after dosing. The correlation coefficients ranged between .517 and .995 among tissues. Correlations were positive between the Rm values and 24 h concentrations in adipose tissue, and kidney, but negative for the relationship between the Rm and 24 h concentrations in blood and liver

Non-invasive diagnostic tests for Helicobacter pylori infection

BACKGROUND: Helicobacter pylori (H pylori) infection has been implicated in a number of malignancies and non-malignant conditions including peptic ulcers, non-ulcer dyspepsia, recurrent peptic ulcer bleeding, unexplained iron deficiency anaemia, idiopathic thrombocytopaenia purpura, and colorectal adenomas. The confirmatory diagnosis of H pylori is by endoscopic biopsy, followed by histopathological examination using haemotoxylin and eosin (H & E) stain or special stains such as Giemsa stain and Warthin-Starry stain. Special stains are more accurate than H & E stain. There is significant uncertainty about the diagnostic accuracy of non-invasive tests for diagnosis of H pylori. OBJECTIVES: To compare the diagnostic accuracy of urea breath test, serology, and stool antigen test, used alone or in combination, for diagnosis of H pylori infection in symptomatic and asymptomatic people, so that eradication therapy for H pylori can be started. SEARCH METHODS: We searched MEDLINE, Embase, the Science Citation Index and the National Institute for Health Research Health Technology Assessment Database on 4 March 2016. We screened references in the included studies to identify additional studies. We also conducted citation searches of relevant studies, most recently on 4 December 2016. We did not restrict studies by language or publication status, or whether data were collected prospectively or retrospectively. SELECTION CRITERIA: We included diagnostic accuracy studies that evaluated at least one of the index tests (urea breath test using isotopes such as13C or14C, serology and stool antigen test) against the reference standard (histopathological examination using H & E stain, special stains or immunohistochemical stain) in people suspected of having H pylori infection. DATA COLLECTION AND ANALYSIS: Two review authors independently screened the references to identify relevant studies and independently extracted data. We assessed the methodological quality of studies using the QUADAS-2 tool. We performed meta-analysis by using the hierarchical summary receiver operating characteristic (HSROC) model to estimate and compare SROC curves. Where appropriate, we used bivariate or univariate logistic regression models to estimate summary sensitivities and specificities. MAIN RESULTS: We included 101 studies involving 11,003 participants, of which 5839 participants (53.1%) had H pylori infection. The prevalence of H pylori infection in the studies ranged from 15.2% to 94.7%, with a median prevalence of 53.7% (interquartile range 42.0% to 66.5%). Most of the studies (57%) included participants with dyspepsia and 53 studies excluded participants who recently had proton pump inhibitors or antibiotics.There was at least an unclear risk of bias or unclear applicability concern for each study.Of the 101 studies, 15 compared the accuracy of two index tests and two studies compared the accuracy of three index tests. Thirty-four studies (4242 participants) evaluated serology; 29 studies (2988 participants) evaluated stool antigen test; 34 studies (3139 participants) evaluated urea breath test-13C; 21 studies (1810 participants) evaluated urea breath test-14C; and two studies (127 participants) evaluated urea breath test but did not report the isotope used. The thresholds used to define test positivity and the staining techniques used for histopathological examination (reference standard) varied between studies. Due to sparse data for each threshold reported, it was not possible to identify the best threshold for each test.Using data from 99 studies in an indirect test comparison, there was statistical evidence of a difference in diagnostic accuracy between urea breath test-13C, urea breath test-14C, serology and stool antigen test (P = 0.024). The diagnostic odds ratios for urea breath test-13C, urea breath test-14C, serology, and stool antigen test were 153 (95% confidence interval (CI) 73.7 to 316), 105 (95% CI 74.0 to 150), 47.4 (95% CI 25.5 to 88.1) and 45.1 (95% CI 24.2 to 84.1). The sensitivity (95% CI) estimated at a fixed specificity of 0.90 (median from studies across the four tests), was 0.94 (95% CI 0.89 to 0.97) for urea breath test-13C, 0.92 (95% CI 0.89 to 0.94) for urea breath test-14C, 0.84 (95% CI 0.74 to 0.91) for serology, and 0.83 (95% CI 0.73 to 0.90) for stool antigen test. This implies that on average, given a specificity of 0.90 and prevalence of 53.7% (median specificity and prevalence in the studies), out of 1000 people tested for H pylori infection, there will be 46 false positives (people without H pylori infection who will be diagnosed as having H pylori infection). In this hypothetical cohort, urea breath test-13C, urea breath test-14C, serology, and stool antigen test will give 30 (95% CI 15 to 58), 42 (95% CI 30 to 58), 86 (95% CI 50 to 140), and 89 (95% CI 52 to 146) false negatives respectively (people with H pylori infection for whom the diagnosis of H pylori will be missed).Direct comparisons were based on few head-to-head studies. The ratios of diagnostic odds ratios (DORs) were 0.68 (95% CI 0.12 to 3.70; P = 0.56) for urea breath test-13C versus serology (seven studies), and 0.88 (95% CI 0.14 to 5.56; P = 0.84) for urea breath test-13C versus stool antigen test (seven studies). The 95% CIs of these estimates overlap with those of the ratios of DORs from the indirect comparison. Data were limited or unavailable for meta-analysis of other direct comparisons. AUTHORS' CONCLUSIONS: In people without a history of gastrectomy and those who have not recently had antibiotics or proton ,pump inhibitors, urea breath tests had high diagnostic accuracy while serology and stool antigen tests were less accurate for diagnosis of Helicobacter pylori infection.This is based on an indirect test comparison (with potential for bias due to confounding), as evidence from direct comparisons was limited or unavailable. The thresholds used for these tests were highly variable and we were unable to identify specific thresholds that might be useful in clinical practice.We need further comparative studies of high methodological quality to obtain more reliable evidence of relative accuracy between the tests. Such studies should be conducted prospectively in a representative spectrum of participants and clearly reported to ensure low risk of bias. Most importantly, studies should prespecify and clearly report thresholds used, and should avoid inappropriate exclusions

Effect of salt stress on phosphorus and sodium absorptions by soybean plants

The radiotracer methodology was combined with the Hoagland solution culture of growing soybean in a greenhouse to investigate the absorptions of phosphorus (P), calcium (Ca), and sodium (Na) as a function of salinity. Salt stress was varied by using zero to 120 mM NaCl. The research was initiated because of a need to increase soybean production in the saline soils of the semi-arid regions of the world. Although P absorption increased with time at each concentration of NaCl, increasing its concentrations ([NaCl]) to 120 mM reduced P uptake considerably. The addition of inorganic P (Pi) to the salt medium improved P absorption significantly (P < 0.0001) in stem, petiole, and roots. Polynomial regressions showed the relationship between 22Na activity and [NaCl] for leaves and petiole to be cubic (R2 = 1) while in the stem a quadratic relationship prevailed. A maximum of P and Na absorption was observed at 40 mM NaCl. The relationship between 32P activity and increasing [NaCl] was linear for the roots (a positive slope) and the stem (a negative slope). 45Ca and 32P dual labelling part of the experiments failed to produce results because an unexpectedly high degree of tissue quenching which prevented from obtaining the minimum counting requirements for separation. Shoot fresh and dry weights decreased linearly with increasing [NaCl] as did the root fresh and dry weights. Leaf chlorophyll content during the last week of the final harvest showed a linear relationship with time. Chlorophyll increased with time linearly when the growth medium contained zero and 40 mM NaCl; whereas a negative slope was obtained for 80 and 120 mM NaCl. It seems that P fertilization of the soil could ameliorate the salt effect. 22 Na uptake results indicated that there is a mechanism for exclusion of Na from soybean plant parts