Assessing hydraulic redistribution with the compensated average gradient heat-pulse method on rain-fed olive trees

Aims

In this study on hydraulic redistribution (HR) in roots, we aimed to use the calibrated average-gradient (CAG) heat-pulse method, the novelty being the use of a much narrower averaging window for the signal analysis, in order to achieve a more linear calibration curve, allowing the HR quantification.

Methods

The study was conducted in 12 large roots of a rain-fed olive orchard, for 6 months without significant rain, when the predawn leaf water potential decreased to ?2.4 MPa, and immediately following the first autumn rains.

Results

Detailed numerical modelling of the CAG method allowed verification of the response of the measurement system to a range of drivers, improving the linear range of the calibration response function, which has remained stable over the observations period. On average, reverse flow was observed during 30% of the summer nights and, in a conservative estimate, it increased to about 5% of total daily root flow before first autumn rain.

Conclusions

Reverse flow accounted on average for 2.6% of the total daily root flow, enabling upper roots to stay active during the very dry late-summer period. In qualitative terms, our results confirm the CAG method as a reliable tool to identify reverse flow and quantify HR when it occurs.

     

Overview on radiation and tissue banking in Latin America

The International Atomic Energy Agency (IAEA) played an important role in the establishment of new tissue banks and the improvement of already existing ones in Latin America. The Agency strongly supported, through regional, interregional and national technical cooperation projects, providing equipment, expert missions and training for the production and application of human tissues for transplantation. From 1999 to 2005 five regional courses were given in Buenos Aires under the modality of 1-year distance learning training courses and 1-week face to face courses. The courses were organized by the IAEA, through the National Atomic Energy Commission (CNEA) and the Faculty of Medicine of Buenos Aires University as Post Graduate Specialization Course. In 2005 the Latin American countries joined with Spain and Portugal, and created the Ibero American Network Council of Donation and Transplant (Red Consejo Iberoamericano de Donación y Trasplantes—RCIDT). The objective of this network is to cooperate among twenty-one Ibero American countries in organizational and legislative aspects, training of professionals, and ethical and social issues related to the donation and transplantation of organs, tissues and cells. The members of this Network work actively to harmonize the regulations and the control of donation and transplantation of human organs, tissues and cells. At present, in Latin America, more than 220 facilities of tissues banks are operating and tissue allografts are being produced by single and multi-tissue banks. The efforts made by the governments and professionals from the region allow the tissue banks to operate under quality systems and introduce new technologies.     

Increased Levels of Rictor Prevent Mutant Huntingtin-Induced Neuronal Degeneration

Rictor associates with mTOR to form the mTORC2 complex, which activity regulates neuronal function and survival. Neurodegenerative diseases are characterized by the presence of neuronal dysfunction and cell death in specific brain regions such as for example Huntington’s disease (HD), which is characterized by the loss of striatal projection neurons leading to motor dysfunction. Although HD is caused by the expression of mutant huntingtin, cell death occurs gradually suggesting that neurons have the capability to activate compensatory mechanisms to deal with neuronal dysfunction and later cell death. Here, we analyzed whether mTORC2 activity could be altered by the presence of mutant huntingtin. We observed that Rictor levels are specifically increased in the striatum of HD mouse models and in the putamen of HD patients. Rictor-mTOR interaction and the phosphorylation levels of Akt, one of the targets of the mTORC2 complex, were increased in the striatum of the R6/1 mouse model of HD suggesting increased mTORC2 signaling. Interestingly, acute downregulation of Rictor in striatal cells in vitro reduced mTORC2 activity, as shown by reduced levels of phospho-Akt, and increased mutant huntingtin-induced cell death. Accordingly, overexpression of Rictor increased mTORC2 activity counteracting cell death. Furthermore, normalization of endogenous Rictor levels in the striatum of R6/1 mouse worsened motor symptoms suggesting an induction of neuronal dysfunction. In conclusion, our results suggest that increased Rictor striatal levels could counteract neuronal dysfunction induced by mutant huntingtin.     

Upstream kinases of plant SnRKs are involved in salt stress tolerance

Sucrose non‐fermenting 1‐related protein kinases (SnRKs) are important for plant growth and stress responses. This family has three clades: SnRK1, SnRK2 and SnRK3. Although plant SnRKs are thought to be activated by upstream kinases, the overall mechanism remains obscure. Geminivirus Rep‐Interacting Kinase (GRIK)1 and GRIK2 phosphorylate SnRK1s, which are involved in sugar/energy sensing, and the grik1‐1 grik2‐1 double mutant shows growth retardation under regular growth conditions. In this study, we established another Arabidopsis mutant line harbouring a different allele of gene GRIK1 (grik1‐2 grik2‐1) that grows similarly to the wild‐type, enabling us to evaluate the function of GRIKs under stress conditions. In the grik1‐2 grik2‐1 double mutant, phosphorylation of SnRK1.1 was reduced, but not eliminated, suggesting that the grik1‐2 mutation is a weak allele. In addition to high sensitivity to glucose, the grik1‐2 grik2‐1 mutant was sensitive to high salt, indicating that GRIKs are also involved in salinity signalling pathways. Salt Overly Sensitive (SOS)2, a member of the SnRK3 subfamily, is a critical mediator of the response to salinity. GRIK1 phosphorylated SOS2 in vitro, resulting in elevated kinase activity of SOS2. The salt tolerance of sos2 was restored to normal levels by wild‐type SOS2, but not by a mutated form of SOS2 lacking the T168 residue phosphorylated by GRIK1. Activation of SOS2 by GRIK1 was also demonstrated in a reconstituted system in yeast. Our results indicate that GRIKs phosphorylate and activate SnRK1 and other members of the SnRK3 family, and that they play important roles in multiple signalling pathways in vivo.     

Cheating on Cheaters Stabilizes Cooperation in Pseudomonas aeruginosa

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Fungal Olecranon Bursitis in an Immunocompetent Patient by <Emphasis Type="Italic">Knoxdaviesia dimorphospora</Emphasis> sp. nov.: Case Report and Review

Bursitis is a common medical condition that can occur either with or without infection. We present a case of fungal olecranon bursitis in an immunocompetent individual caused by the new species Knoxdaviesia dimorphospora. It is a dematiaceous filamentous fungus characterized by the production of two different conidia: hyaline and cylindrical, which rise up from phialidic conidiogenous cells located in the upper part of differentiated and unbranched conidiophores, and pale brown and ellipsoidal conidia produced by phialidic conidiogenous cells which are born directly on hyphae. In addition to its morphological peculiarities, the novelty of the fungus was confirmed by sequence analysis of the internal transcribed spacer (ITS) regions and D1/D2 domains of the 28S of the nuclear rRNA gene. The fungal infection was confirmed by cytological examination and repeated cultures. The infection was resolved by surgical debridement and drainage, and the patient presented a complete functional recovery 3 months later. The in vitro antifungal susceptibility to this new human opportunist is provided, terbinafine being the drug with the most potent activity.