New targets of Arabidopsis thioredoxins revealed by proteomic analysis

Proteomics was used to search for putative thioredoxin (TRX) targets in leaves of the model plant, Arabidopsis thaliana. About forty different proteins have been found to be reduced by TRX, after TRX itself has been specifically reduced by its NADPH-dependent reductase. Twenty-one of the identified proteins were already known or recently proposed to be TRX-dependent and nineteen of the proteins were new potential targets. The identified proteins are involved in a wide variety of processes, including the Calvin cycle, metabolism, photosynthesis, folding, defense against oxidative stress and amino acid synthesis. Two proteins from the glycine cleavage complex were also identified as putative TRX targets, and a new role can be postulated in leaves for TRX in defense against herbivores and/or pathogens.     

Sensitivity to stress-induced reproductive dysfunction is associated with a selective but not a generalized increase in activity of the adrenal axis

Stress-induced reproductive dysfunction is a relatively common cause of infertility in women. In response to everyday life stress, some individuals readily develop reproductive dysfunction (i.e., they are stress sensitive), whereas others are more stress resilient. Female cynomolgus monkeys, when exposed to mild combined psychosocial and metabolic stress (change in social environment + 20% reduced calorie diet), can be categorized as stress sensitive (SS; they rapidly become anovulatory in response to stress), medium stress resilient (MSR; they slowly become anovulatory in response to prolonged stress), or highly stress resilient (HSR; they maintain normal menstrual cycles in response to stress). In this study, we examined whether increased sensitivity to stress-induced reproductive dysfunction is associated with elevated adrenal axis activity by measuring 1) the diurnal release of ACTH and cortisol, 2) ACTH and cortisol in response to an acute psychological stress, 3) the percent suppression of cortisol in response to dexamethasone negative feedback, 4) the diurnal release of ACTH and cortisol following exposure to mild psychosocial and metabolic stress, 5) the concentration of cortisol in hair, and 6) adrenal weight. SS monkeys (n = 5) did not differ from MSR (n = 5) or HSR (n = 7) monkeys in any measurement of baseline HPA axis activity or the integrated measurements of chronic HPA axis activity. However, MSR + SS monkeys (n = 10) did secrete more cortisol than HSR monkeys during the daytime hours (1000-1800) following exposure to a novel social environment and reduced diet. We conclude that increased activity of the HPA axis is unlikely to be the primary mechanism causing increased sensitivity to stress-induced reproductive dysfunction.     

Secretion in yeast. Purification and in vitro translocation of chemical amounts of prepro-alpha-factor

The Saccharomyces cerevisiae mating pheromone precursor, prepro-alpha-factor, can be translocated across yeast endoplasmic reticulum membranes post-translationally in an in vitro system. This characteristic makes prepro-alpha-factor potentially useful as a probe in the biochemical dissection of the mechanism of this basic cellular process. Efforts have been limited by the inability to isolate sufficient quantities of such secretory protein precursors in a translocation-competent form. We report here the one-step purification of chemical amounts of translocation-competent prepro-alpha-factor using nickel ion affinity chromatography on nitrilotriacetate resin. An oligonucleotide encoding 6 histidine residues was inserted into a genomic clone encoding prepro-alpha-factor 5' of the naturally occurring translational stop codon by site-directed mutagenesis. The construct was expressed at high levels in a SecY- strain of Escherichia coli. The produced preprotein was solubilized in 6 M guanidine hydrochloride and bound to nitrilotriacetate resin. Prepro-alpha-factor was recovered at a purity in excess of 95% by elution with 0.25 M imidazole, 8 M urea, which competitively displaced the histidine affinity tag from the nickel column. The chemical amounts of prepro-alpha-factor obtained in this way were determined to be competent for translocation across yeast microsomal membranes and for subsequent modifications such as signal sequence cleavage and N-linked glycosylation.     

Selenoprotein P Status Correlates to Cancer-Specific Mortality in Renal Cancer Patients

Selenium (Se) is an essential trace element for selenoprotein biosynthesis. Selenoproteins have been implicated in cancer risk and tumor development. Selenoprotein P (SePP) serves as the major Se transport protein in blood and as reliable biomarker of Se status in marginally supplied individuals. Among the different malignancies, renal cancer is characterized by a high mortality rate. In this study, we aimed to analyze the Se status in renal cell cancer (RCC) patients and whether it correlates to cancer-specific mortality. To this end, serum samples of RCC patients (n = 41) and controls (n = 21) were retrospectively analyzed. Serum Se and SePP concentrations were measured by X-ray fluorescence and an immunoassay, respectively. Clinical and survival data were compared to serum Se and SePP concentrations as markers of Se status by receiver operating characteristic (ROC) curve and Kaplan-Meier and Cox regression analyses. In our patients, higher tumor grade and tumor stage at diagnosis correlated to lower SePP and Se concentrations. Kaplan-Meier analyses indicated that low Se status at diagnosis (SePP<2.4 mg/l, bottom tertile of patient group) was associated with a poor 5-year survival rate of 20% only. We conclude that SePP and Se concentrations are of prognostic value in RCC and may serve as additional diagnostic biomarkers identifying a Se deficit in kidney cancer patients potentially affecting therapy regimen. As poor Se status was indicative of high mortality odds, we speculate that an adjuvant Se supplementation of Se-deficient RCC patients might be beneficial in order to stabilize their selenoprotein expression hopefully prolonging their survival. However, this assumption needs to be rigorously tested in prospective clinical trials.     

River Restoration in the Twenty-First Century: Data and Experiential Knowledge to Inform Future Efforts

Despite some highly visible projects that have resulted in environmental benefits, recent efforts to quantify the number and distribution of river restoration projects revealed a paucity of written records documenting restoration outcomes. Improving restoration designs and setting watershed priorities rely on collecting and making accessible this critical information. Information within the unpublished notes of restoration project managers is useful but rarely documents ecological improvements. This special section of Restoration Ecology is devoted to the current state of knowledge on river restoration. We provide an overview of the section’s articles, reflecting on lessons learned, which have implications for the implementation, legal, and financing frameworks for restoration. Our reflections are informed by two databases developed under the auspices of the National River Restoration Science Synthesis project and by extensive interactions with those who fund, implement, and permit restoration. Requiring measurable ecological success criteria, comprehensive watershed plans, and tracking of when and where restoration projects are implemented are critical to improving the health of U.S. waters. Documenting that a project was put in the ground and stayed intact cannot be equated with ecological improvements. However, because significant ecological improvements can come with well‐designed and ‐implemented stream and river restorations, a small investment in documenting the factors contributing to success will lead to very large returns in the health of our nation’s waterways. Even projects that may appear to be failures initially can be turned into success stories by applying the knowledge gained from monitoring the project in an adaptive restoration approach.     

Distinguishing Neurocognitive Processes Reflected by P600 Effects: Evidence from ERPs and Neural Oscillations

Research on language comprehension using event-related potentials (ERPs) reported distinct ERP components reliably related to the processing of semantic (N400) and syntactic information (P600). Recent ERP studies have challenged this well-defined distinction by showing P600 effects for semantic and pragmatic anomalies. So far, it is still unresolved whether the P600 reflects specific or rather common processes. The present study addresses this question by investigating ERPs in response to a syntactic and pragmatic (irony) manipulation, as well as a combined syntactic and pragmatic manipulation. For the syntactic condition, a morphosyntactic violation was applied, whereas for the pragmatic condition, such as “That is rich”, either an ironic or literal interpretation was achieved, depending on the prior context. The ERPs at the critical word showed a LAN-P600 pattern for syntactically incorrect sentences relative to correct ones. For ironic compared to literal sentences, ERPs showed a P200 effect followed by a P600 component. In comparison of the syntax-related P600 to the irony-related P600, distributional differences were found. Moreover, for the P600 time window (i.e., 500–900 ms), different changes in theta power between the syntax and pragmatics effects were found, suggesting that different patterns of neural activity contributed to each respective effect. Thus, both late positivities seem to be differently sensitive to these two types of linguistic information, and might reflect distinct neurocognitive processes, such as reanalysis of the sentence structure versus pragmatic reanalysis.