Phosphorylation of Phosphoenolpyruvate Carboxylase Is Essential for Maximal and Sustained Dark CO2 Fixation and Core Circadian Clock Operation in the Obligate Crassulacean Acid Metabolism Species Kalanchoe fedtschenkoi

Phosphoenolpyruvate carboxylase (PPC; EC 4.1.1.31) catalyzes primary nocturnal CO2 fixation in Crassulacean acid metabolism (CAM) species. CAM PPC is regulated posttranslationally by a circadian clock-controlled protein kinase called phosphoenolpyruvate carboxylase kinase (PPCK). PPCK phosphorylates PPC during the dark period, reducing its sensitivity to feedback inhibition by malate and thus enhancing nocturnal CO2 fixation to stored malate. Here, we report the generation and characterization of transgenic RNAi lines of the obligate CAM species Kalanchoë fedtschenkoi with reduced levels of KfPPCK1 transcripts. Plants with reduced or no detectable dark phosphorylation of PPC displayed up to a 66% reduction in total dark period CO2 fixation. These perturbations paralleled reduced malate accumulation at dawn and decreased nocturnal starch turnover. Loss of oscillations in the transcript abundance of KfPPCK1 was accompanied by a loss of oscillations in the transcript abundance of many core circadian clock genes, suggesting that perturbing the only known link between CAM and the circadian clock feeds back to perturb the central circadian clock itself. This work shows that clock control of KfPPCK1 prolongs the activity of PPC throughout the dark period in K. fedtschenkoi, optimizing CAM-associated dark CO2 fixation, malate accumulation, CAM productivity, and core circadian clock robustness

Nanopore direct RNA sequencing maps the complexity of Arabidopsis mRNA processing and m6A modification

Understanding genome organization and gene regulation requires insight into RNA transcription, processing and modification. We adapted nanopore direct RNA sequencing to examine RNA from a wild-type accession of the model plant Arabidopsis thaliana and a mutant defective in mRNA methylation (m6A). Here we show that m6A can be mapped in full-length mRNAs transcriptome-wide and reveal the combinatorial diversity of cap-associated transcription start sites, splicing events, poly(A) site choice and poly(A) tail length. Loss of m6A from 3’ untranslated regions is associated with decreased relative transcript abundance and defective RNA 30 end formation. A functional consequence of disrupted m6A is a lengthening of the circadian period. We conclude that nanopore direct RNA sequencing can reveal the complexity of mRNA processing and modification in full-length single molecule reads. These findings can refine Arabidopsis genome annotation. Further, applying this approach to less well-studied species could transform our understanding of what their genomes encode

Kalanchoe PPC1 Is Essential for Crassulacean Acid Metabolism and the Regulation of Core Circadian Clock and Guard Cell Signaling Genes([CC-BY])

Unlike C3 plants, Crassulacean acid metabolism (CAM) plants fix CO2 in the dark using phosphoenolpyruvate carboxylase (PPC; EC 4.1.1.31). PPC combines phosphoenolpyruvate with CO2 (as HCO3−), forming oxaloacetate. The oxaloacetate is converted to malate, leading to malic acid accumulation in the vacuole, which peaks at dawn. During the light period, malate decarboxylation concentrates CO2 around Rubisco for secondary fixation. CAM mutants lacking PPC have not been described. Here, we employed RNA interference to silence the CAM isogene PPC1 in Kalanchoë laxiflora. Line rPPC1-B lacked PPC1 transcripts, PPC activity, dark period CO2 fixation, and nocturnal malate accumulation. Light period stomatal closure was also perturbed, and the plants displayed reduced but detectable dark period stomatal conductance and arrhythmia of the CAM CO2 fixation circadian rhythm under constant light and temperature free-running conditions. By contrast, the rhythm of delayed fluorescence was enhanced in plants lacking PPC1. Furthermore, a subset of gene transcripts within the central circadian oscillator was upregulated and oscillated robustly in this line. The regulation of guard cell genes involved in controlling stomatal movements was also perturbed in rPPC1-B. These findings provide direct evidence that the regulatory patterns of key guard cell signaling genes are linked with the characteristic inverse pattern of stomatal opening and closing during CAM

Effect of Sun and Planet-Bound Dark Matter on Planet and Satellite Dynamics in the Solar System

We apply our recent results on orbital dynamics around a mass-varying central body to the phenomenon of accretion of Dark Matter-assumed not self-annihilating-on the Sun and the major bodies of the solar system due to its motion throughout the Milky Way halo. We inspect its consequences on the orbits of the planets and their satellites over timescales of the order of the age of the solar system. It turns out that a solar Dark Matter accretion rate of \approx 10^-12 yr^-1, inferred from the upper limit \Delta M/M= 0.02-0.05 on the Sun's Dark Matter content, assumed somehow accumulated during last 4.5 Gyr, would have displaced the planets faraway by about 10^-2-10^1 au 4.5 Gyr ago. Another consequence is that the semimajor axis of the Earth's orbit, approximately equal to the Astronomical Unit, would undergo a secular increase of 0.02-0.05 m yr^-1, in agreement with the latest observational determinations of the Astronomical Unit secular increase of 0.07 +/- 0.02 m yr^-1 and 0.05 m yr^-1. By assuming that the Sun will continue to accrete Dark Matter in the next billions year at the same rate as in the past, the orbits of its planets will shrink by about 10^-1-10^1 au (\approx 0.2-0.5 au for the Earth), with consequences for their fate, especially of the inner planets. On the other hand, lunar and planetary ephemerides set upper bounds on the secular variation of the Sun's gravitational parameter GM which are one one order of magnitude smaller than 10^-12 yr^-1. Dark Matter accretion on planets has, instead, less relevant consequences for their satellites. Indeed, 4.5 Gyr ago their orbits would have been just 10^-2-10^1 km wider than now. (Abridged)Comment: LaTex2e, 17 pages, no figures, 7 tables, 61 references. Small problem with a reference fixed. To appear in Journal of Cosmology and Astroparticle Physics (JCAP

A life in progress: motion and emotion in the autobiography of Robert M. La Follette

This article is a study of a La Follette’s Autobiography, the autobiography of the leading Wisconsin progressive Robert M. La Follette, which was published serially in 1911 and, in book form, in 1913. Rather than focusing, as have other historians, on which parts of La Follette’s account are accurate and can therefore be trusted, it explains instead why and how this major autobiography was conceived and written. The article shows that the autobiography was the product of a sustained, complex, and often fraught series of collaborations among La Follette’s family, friends, and political allies, and in the process illuminates the importance of affective ties as well as political ambition and commitment in bringing the project to fruition. In the world of progressive reform, it argues, personal and political experiences were inseparable

Fermion sea along the sphaleron barrier

In this revised version we have improved the treatment of the top and bottom quark mass. This leads to slight changes of the numerical results, especially of those presented in Fig.4. The discussion of the numerical procedure and accuracy has been extended.Comment: 39 pages (LaTex) plus 5 figures (uuencoded postscript files); RUB-TPII-62/93, to appear in Phys.Rev.

Magnetic field-induced exchange effects between Mn ions and free carriers in ZnSe quantum well through the intermediate nonmagnetic barrier studied by photoluminescence

Photoluminescence (PL) of the 50 nm $Zn_{0.9}Be_{0.05}Mn_{0.05}Se$/ $d$ nm $Zn_{0.943}Be_{0.057}Se$/ 2.5 nm $ZnSe$/ 30 nm $Zn_{0.943}Be_{0.057}Se$ structures is investigated as a function of magnetic field ($B$) and thickness ($d$) of intermediate $Zn_{0.943}Be_{0.057}Se$ nonmagnetic barrier between the $Zn_{0.9}Be_{0.05}Mn_{0.05}Se$ semimagnetic barrier and $ZnSe$ quantum well at the temperature 1.2 K. The rate of the shift of different PL bands of the structures under study is estimated in low and high magnetic fields. The causes of the shift rate increase under pass from low to high magnetic fields are interpreted. The peculiarities of the effect of the intermediate barrier on the luminescence properties of the structures are presented. It is shown that deformation of adjacent layers by the barrier plays a crucial role in the formation of these properties, especially in forming the $Mn$ complexes in the $Zn_{0.9}Be_{0.05}Mn_{0.05}Se$ layer. The change of the band gap as well as of the donor and acceptor levels energies under the effect of biaxial compression of the $Zn_{0.9}Be_{0.05}Mn_{0.05}Se$ layer by the $Zn_{0.943}Be_{0.057}Se$ are estimated. It is concluded that the $Zn_{0.943}Be_{0.057}Se$ intermediate barrier also appreciably changes the effect of giant Zeeman splitting of the semimagnetic $Zn_{0.9}Be_{0.05}Mn_{0.05}Se$ barrier energy levels on the movement of the energy levels of $ZnSe$ quantum well in a magnetic field and on polarization of the quantum well exciton emission

Limited effect of patient and disease characteristics on compliance with hospital antimicrobial guidelines

Objective: Physicians frequently deviate from guidelines that promote prudent use of antimicrobials. We explored to what extent patient and disease characteristics were associated with compliance with guideline recommendations for three common infections. Methods: In a 1-year prospective observational study, 1,125 antimicrobial prescriptions were analysed for compliance with university hospital guidelines. Results: Compliance varied significantly between and within the groups of infections studied. Compliance was much higher for lower respiratory tract infections (LRTIs; 79%) than for sepsis (53%) and urinary tract infections (UTIs; 40%). Only predisposing illnesses and active malignancies were associated with more compliant prescribing, whereas alcohol/ intravenous drug abuse and serum creatinine levels > 130 mu mol/l were associated with less compliant prescribing. Availability of culture results had no impact on compliance with guidelines for sepsis but was associated with more compliance in UTIs and less in LRTIs. Narrowing initial broad-spectrum antimicrobial therapy to cultured pathogens was seldom practised. Most noncompliant prescribing concerned a too broad spectrum of activity when compared with guideline-recommended therapy. Conclusion: Patient characteristics had only a limited impact on compliant prescribing for a variety of reasons. Physicians seemed to practise defensive prescribing behaviour, favouring treatment success in current patients over loss of effectiveness due to resistance in future patients

A Seven-Marker Signature and Clinical Outcome in Malignant Melanoma: A Large-Scale Tissue-Microarray Study with Two Independent Patient Cohorts

Current staging methods such as tumor thickness, ulceration and invasion of the sentinel node are known to be prognostic parameters in patients with malignant melanoma (MM). However, predictive molecular marker profiles for risk stratification and therapy optimization are not yet available for routine clinical assessment.; Using tissue microarrays, we retrospectively analyzed samples from 364 patients with primary MM. We investigated a panel of 70 immunohistochemical (IHC) antibodies for cell cycle, apoptosis, DNA mismatch repair, differentiation, proliferation, cell adhesion, signaling and metabolism. A marker selection procedure based on univariate Cox regression and multiple testing correction was employed to correlate the IHC expression data with the clinical follow-up (overall and recurrence-free survival). The model was thoroughly evaluated with two different cross validation experiments, a permutation test and a multivariate Cox regression analysis. In addition, the predictive power of the identified marker signature was validated on a second independent external test cohort (n?=?225). A signature of seven biomarkers (Bax, Bcl-X, PTEN, COX-2, loss of ?-Catenin, loss of MTAP, and presence of CD20 positive B-lymphocytes) was found to be an independent negative predictor for overall and recurrence-free survival in patients with MM. The seven-marker signature could also predict a high risk of disease recurrence in patients with localized primary MM stage pT1-2 (tumor thickness ?2.00 mm). In particular, three of these markers (MTAP, COX-2, Bcl-X) were shown to offer direct therapeutic implications.; The seven-marker signature might serve as a prognostic tool enabling physicians to selectively triage, at the time of diagnosis, the subset of high recurrence risk stage I-II patients for adjuvant therapy. Selective treatment of those patients that are more likely to develop distant metastatic disease could potentially lower the burden of untreatable metastatic melanoma and revolutionize the therapeutic management of MM

Characteristics of Kepler Planetary Candidates Based on the First Data Set: The Majority are Found to be Neptune-Size and Smaller

In the spring of 2009, the Kepler Mission commenced high-precision photometry on nearly 156,000 stars to determine the frequency and characteristics of small exoplanets, conduct a guest observer program, and obtain asteroseismic data on a wide variety of stars. On 15 June 2010 the Kepler Mission released data from the first quarter of observations. At the time of this publication, 706 stars from this first data set have exoplanet candidates with sizes from as small as that of the Earth to larger than that of Jupiter. Here we give the identity and characteristics of 306 released stars with planetary candidates. Data for the remaining 400 stars with planetary candidates will be released in February 2011. Over half the candidates on the released list have radii less than half that of Jupiter. The released stars include five possible multi-planet systems. One of these has two Neptune-size (2.3 and 2.5 Earth-radius) candidates with near-resonant periods.Comment: Paper to accompany Kepler's June 15, 2010 data release; submitted to Astrophysical Journal Figures 1,2,& 3 revised. Improved labeling on all figures. Slight changes to planet frequencies in result