Rapid purification of grapevine RNA by a simple electrophoretic method

Research Not

Characterization of Agrobacterium tumefaciens strains isolated from grapevine

Grapevine crown gall is predominantly induced by Agrobacterium vitis, but rarely, Agrobacterium tumefaciens may also cause this disease. We have collected 18 grapevine isolates of A. tumefaciens from distinct geographical regions and various grapevine varieties. Characterization of these strains showed that 7 of the 18 strains carried A. vitis-type octopine/cucumopine Ti plasmids, utilized tartrate, were avirulent on pea and did not respond to the virC-specific PCR primers like A. vitis. Eleven of the 18 strains carried A. tumefaciens-type Ti plasmids, did not grow on tartrate, were virulent on pea and reacted positively to virC-specific PCR primers. Two of these strains induced octopine/agropine-, and two strains induced agropine producing tumors on grapevine and/or Kalanchoe tubiflora plants. The remaining 7 strains showed the characteristic properties of A. tumefaciens nopaline strains and were sensitive to agrocin 84

Identification of Young Stellar Object candidates in the GaiaGaia DR2 x AllWISE catalogue with machine learning methods

The second $Gaia$ Data Release (DR2) contains astrometric and photometric data for more than 1.6 billion objects with mean $Gaia$ $G$ magnitude $<$20.7, including many Young Stellar Objects (YSOs) in different evolutionary stages. In order to explore the YSO population of the Milky Way, we combined the $Gaia$ DR2 database with WISE and Planck measurements and made an all-sky probabilistic catalogue of YSOs using machine learning techniques, such as Support Vector Machines, Random Forests, or Neural Networks. Our input catalogue contains 103 million objects from the DR2xAllWISE cross-match table. We classified each object into four main classes: YSOs, extragalactic objects, main-sequence stars and evolved stars. At a 90% probability threshold we identified 1,129,295 YSO candidates. To demonstrate the quality and potential of our YSO catalogue, here we present two applications of it. (1) We explore the 3D structure of the Orion A star forming complex and show that the spatial distribution of the YSOs classified by our procedure is in agreement with recent results from the literature. (2) We use our catalogue to classify published $Gaia$ Science Alerts. As $Gaia$ measures the sources at multiple epochs, it can efficiently discover transient events, including sudden brightness changes of YSOs caused by dynamic processes of their circumstellar disk. However, in many cases the physical nature of the published alert sources are not known. A cross-check with our new catalogue shows that about 30% more of the published $Gaia$ alerts can most likely be attributed to YSO activity. The catalogue can be also useful to identify YSOs among future $Gaia$ alerts.Comment: 19 pages, 12 figures, 3 table

Activity of 50 Long-Period Comets Beyond 5.2 AU

Remote investigations of the ancient solar system matter has been traditionally carried out through the observations of long-period (LP) comets that are less affected by solar irradiation than the short-period counterparts orbiting much closer to the Sun. Here we summarize the results of our decade-long survey of the distant activity of LP comets. We found that the most important separation in the dataset is based on the dynamical nature of the objects. Dynamically new comets are characterized by a higher level of activity on average: the most active new comets in our sample can be characterized by afrho values >3--4 higher than that of our most active returning comets. New comets develop more symmetric comae, suggesting a generally isotropic outflow. Contrary to this, the coma of recurrent comets can be less symmetrical, ocassionally exhibiting negative slope parameters, suggesting sudden variations in matter production. The morphological appearance of the observed comets is rather diverse. A surprisingly large fraction of the comets have long, teniouos tails, but the presence of impressive tails does not show a clear correlation with the brightness of the comets.Comment: 21 pages, 4 figures, accepted for publication in A

Gravity is an important determinant of Oxygenation during One-Lung Ventilation

The role of gravity in the redistribution of pulmonary blood flow during one-lung ventilation (OLV) has recently been questioned. To address this controversial but clinically important issue we used an experimental approach that allowed us to differentiate the effects of gravity from the effects of hypoxic pulmonary vasoconstriction on arterial oxygenation during OLV in patients scheduled for thoracic surger

Bacterial diseases of grapevine

Grapevines are affected by three major bacterial diseases worldwide, such as bacterial blight (Xylophilus ampelinus), Pierce’sdisease (Xylella fastidiosa) and crown gall (Agrobacterium vitis). These bacteria grow in the vascular system of their host, thus they invadeand colonize the whole plant, independently on symptom development. Latently infected propagating material is a major factor in theirspreading. Therefore the use of bacteria-free planting stock has a basic importance in viticulture. Today several innovative diagnosticmethods, mostly based on polymerase chain reaction, are available to detect and identify bacterial pathogens of grapevines. For production ofbacteria-free plants, the use hot water treatment followed by establishment of in vitro shoot tip cultures is proposed

Novel pathogen-specific primers for the detection of Agrobacterium vitis and Agrobacterium tumefaciens

To detect agrobacteria causing crown gall disease of grapevine novel virulence and oncogene specific primer combinations were tested on Agrobacterium vitis and Agrobacterium tumefaciens strains including most opine types found in grapevines. Reproducible detection of all the tested pathogens in a single reaction was only possible with multiplex PCR using mixtures of virulence-, or oncogene specific primers. A primer combination including pehA, virF and virD2 gene-specific oligonucleotides amplified the corresponding fragments from nearly all strains included and distinguished A. vitis and A. tumefaciens strains carrying octopine or nopaline pTis and A. vitis vitopine strains. A second set of primers designed to amplify the T-DNA auxin genes iaaH and iaaM detected all of the tested pathogens and, as in the case of virF-, and virD2-specific primers, A. vitis vitopine strains formed also a distinct group. These data were further confirmed using opine synthase-, or 6b gene-specific primers that also allowed the identification and distinction of octopine and nopaline as well as vitopine isolates of A. vitis. Thus, a wide range of agrobacteria occurring on grapevine were detected and identified. On the other hand, our results confirm that vitopine-type agrobacteria form a distinct group within the genus Agrobacterium.