Correction: The AGC protein kinase UNICORN controls planar growth by attenuating PDK1 in Arabidopsis thaliana.

[This corrects the article DOI: 10.1371/journal.pgen.1007927.].

The AGC protein kinase UNICORN controls planar growth by attenuating PDK1 in Arabidopsis thaliana.

Tissue morphogenesis critically depends on the coordination of cellular growth patterns. In plants, many organs consist of clonally distinct cell layers, such as the epidermis, whose cells undergo divisions that are oriented along the plane of the layer. The developmental control of such planar growth is poorly understood. We have previously identified the Arabidopsis AGCVIII-class protein kinase UNICORN (UCN) as a central regulator of this process. Plants lacking UCN activity show spontaneous formation of ectopic multicellular protrusions in integuments and malformed petals indicating that UCN suppresses uncontrolled growth in those tissues. In the current model UCN regulates planar growth of integuments in part by directly repressing the putative transcription factor ABERRANT TESTA SHAPE (ATS). Here we report on the identification of 3-PHOSPHOINOSITIDE-DEPENDENT PROTEIN KINASE 1 (PDK1) as a novel factor involved in UCN-mediated growth control. PDK1 constitutes a basic component of signaling mediated by AGC protein kinases throughout eukaryotes. Arabidopsis PDK1 is implied in stress responses and growth promotion. Here we show that loss-of-function mutations in PDK1 suppress aberrant growth in integuments and petals of ucn mutants. Additional genetic, in vitro, and cell biological data support the view that UCN functions by repressing PDK1. Furthermore, our data indicate that PDK1 is indirectly required for deregulated growth caused by ATS overexpression. Our findings support a model proposing that UCN suppresses ectopic growth in integuments through two independent processes: the attenuation of the protein kinase PDK1 in the cytoplasm and the repression of the transcription factor ATS in the nucleus.

Kinetic modeling of the adsorption and desorption of CO2 on α-Fe2O3.

The present paper addresses the interaction of CO2 with polycrystalline α-Fe2O3 revealing considerable catalytic activity in CO oxidation to yield CO2. The mechanism of adsorption and desorption of CO2 was investigated by diffuse reflectance infrared fourier transform spectroscopy (DRIFTS), while the kinetics was examined by temperature-programmed desorption (CO2-TPD). For numeric modeling as well as simulation of the surface coverage, an elementary kinetic mean field model was constructed using Arrhenius-based rate expressions. The kinetic parameters of desorption were taken from fitting calculations (A2 = 3.01 × 10(5) mol (m(2) s)(-1), E2(0) = 112.8 kJ mol(-1), α2 = 70.2 kJ mol(-1)), whereas the adsorption was considered to be non-activated and the pre-exponential factor was estimated from kinetic gas theory (A1 = 0.0192 m s(-1), E1 = 0 kJ mol(-1)). For model validation, predicted and experimental CO2-TPD profiles were compared and thermodynamic consistency was evaluated by using differential scanning calorimetry (ΔadsH(250 °C) = -129 kJ mol(-1)) as well as literature data.

Degradation of selected (bio-)surfactants by bacterial cultures monitored by calorimetric methods.

The subjects of the article are investigations concerning the ability of both Rhodococcus opacus 1CP and mixed bacterial cultures to use selected surfactants as sole carbon and energy source. In a comparative manner the biosurfactants rhamnolipid, sophorolipid and trehalose tetraester, and the synthetic surfactant Tween 80 were examined. Particular emphasis was put on a combinatorial approach to determine quantitatively the degree of surfactant degradation by applying calorimetry, thermodynamic calculations and mass spectrometry, HPLC as well as determination of biomass. The pure bacterial strain R. opacus was only able to metabolize a part of the synthetic surfactant Tween 80, whereas the mixed bacterial cultures degraded all of the applied surfactants. Exclusive for the biosurfactant rhamnolipid a complete microbial degradation could be demonstrated. In the case of the other surfactants only primary degradation was observed.

Calorimetric investigations into the starvation response of Pseudomonas putida growing on phenol and glucose.

AIMS: To investigate the stress response during nutrient deprivation, particularly with regard to the application of phenol as growth substrate of Pseudomonas putida with calorimetric measurements as a new method. METHODS AND RESULTS: The online and noninvasive measurement of the thermal power P(0) permits the detection of microbial activity during the starvation period. While the results of the investigations with phenol reveal a significant loss of activity as a function of the temporal nutrient dosage, only a small loss of activity was detected by using glucose. Microbiological methods (colony forming units (CFU) and activity of catechol-2,3-dioxygenase) showed a loss of the enzyme activity at a constant CFU. The introduction of a simple decay parameter k(D) in the kinetic description of the growth process on phenol was sufficient for the successful kinetic modelling. CONCLUSIONS: The combination of calorimetric measurements and the determination of the enzymatic activity proved the loss of activity of Ps. putida during the deprivation of the substrate phenol. SIGNIFICANCE AND IMPACT OF THE STUDY: The initial heat power (P(0)) proves to be a suitable parameter for the characterization of the physiological state of the culture and can be used for the regulation of nutrient supply in biotechnological process development.