Effects of Exogenous Auxins on Tomato Tissue Infected With the Citrus Exocortis Viroid

Leaf disks, stem segments, and callus cultures from healthy and CEVinfected plants of a hybrid of Lycopersicon esculentum and Lycopersicon peruvianum were cultured in vitro under different hormone regimes. The differences in response observed when the medium was supplemented with auxins, alone or in combination with cytokinins, suggest that the inability of CEV-infected cells to respond to auxins might be involved in the development of the pathogenic syndrome caused by CEV

The vein-banding disease syndrome: A synergistic reaction between grapevine viroids and fanleaf virus

Viroid-free Vitis vinifera cultivars Cabernet Sauvignon and Sauvignon blanc were established in controlled field trials in California to evaluate the relationship between grapevine viroids and fanleaf virus for induction of the vein-banding disease. Vein-banding symptoms were observed only on vines which contained the three principal grapevine viroids, grapevine yellow speckle viroids (GYSVd-1, GYSVd-2), and hop stunt viroid (HSVd-g), as well as grapevine fanleaf virus (GFLV). Sauvignon blanc vines which contained the single viroid, HSVd-g, and GFLV were non-symptomatic indicating an absence of a correlation between HSVd-g and the vein-banding disease. The intensity of vein-banding symptoms was directly correlated with an enhanced titer of GYSVd-1 and GYSVd-2. Vein-banding and yellow speckle symptomatic as well as non-symptomatic vines in Italy contained two viroids, GYSVd-1 and HSVd-g. However, symptomatic vines displayed a higher titer of GYSVd-1 than non-symptomatic materials and vein-banding symptomatic vines were GFLV infected. These data experimentally demonstrate that expression of the vein-banding disease is induced by an unique synergistic reaction between a viroid, GYSVd-1 and a virus, GFLV

Relationship and patterns of distribution among grapevine viroids from California and Europe

Analyses of California and European grapevine sources indicated a ubiquitous occurrence of viroids in these materials. Hybridization results indicated sequence homology to both GV-1 and GV-3 for viroids of varieties grown in California as well as from European sources. Wine and rootstock varieties contained a greater proportion of the more common GV-1 plus GV-3 viroid profile, whereas the table varieties contained a larger proportion of the relatively unusual viroid profile of GV-1, -2, and-3. An unexpected divergence of four viroid profiles emerged in the rootstock species. These profiles were 1) Gv-1, -2, and -3, 2) GV-1 plus GV-3, 3) GV-3, and 4) viroid-free. V. californica was the only grapevine analyzed which was found to be viroid-free

The Citrus Exocortis Disease: A Complex of Viroid-RNAs

Citrons inoculated with different field sources, displayed a variety of symptoms ranging from very mild leaf bending and necrosis to the severe reaction normally associated with exocortis disease. Nucleic acid preparations from shoot samples were analyzed by sequential polyacrylamide gel electrophoresis. All source from both California and Spain contained one to four viroids with distinct physical and biological properties. The size range was estimated from 371 nucleotides for the citrus exocortis viroid (CEV) to 275 for the smallest viroid. The recovery of single viroids suggested a relationship between the distinct viroids and the symptom reaction expressed in citron

Dual Mode NOx Sensor: Measuring Both the Accumulated Amount and Instantaneous Level at Low Concentrations

The accumulating-type (or integrating-type) NOx sensor principle offers two operation modes to measure low levels of NOx: The direct signal gives the total amount dosed over a time interval and its derivative the instantaneous concentration. With a linear sensor response, no baseline drift, and both response times and recovery times in the range of the gas exchange time of the test bench (5 to 7 s), the integrating sensor is well suited to reliably detect low levels of NOx. Experimental results are presented demonstrating the sensor’s integrating properties for the total amount detection and its sensitivity to both NO and to NO2. We also show the correlation between the derivative of the sensor signal and the known gas concentration. The long-term detection of NOx in the sub-ppm range (e.g., for air quality measurements) is discussed. Additionally, a self-adaption of the measurement range taking advantage of the temperature dependency of the sensitivity is addressed

The ϕ6 Cystovirus Protein P7 Becomes Accessible to Antibodies in the Transcribing Nucleocapsid: A Probe for Viral Structural Elements

Protein P7 is a component of the cystovirus viral polymerase complex. In the unpackaged procapsid, the protein is situated in close proximity to the viral directed RNA polymerase, P2. Cryo-electron microscopy difference maps from the species ϕ6 procapsid have demonstrated that P7 and P2 likely interact prior to viral RNA packaging. The location of P7 in the post-packaged nucleocapsid (NC) remains unknown. P7 may translocate closer to the five-fold axis of a filled procapsid but this has not been directly visualized. We propose that monoclonal antibodies (Mabs) can be selected that serve as probe- reagents for viral assembly and structure. A set of Mabs have been isolated that recognize and bind to the ϕ6 P7. The antibody set contains five unique Mabs, four of which recognize a linear epitope and one which recognizes a conformational epitope. The four unique Mabs that recognize a linear epitope display restricted utilization of Vκ and VH genes. The restricted genetic range among 4 of the 5 antibodies implies that the antibody repertoire is limited. The limitation could be the consequence of a paucity of exposed antigenic sites on the ϕ6 P7 surface. It is further demonstrated that within ϕ6 nucleocapsids that are primed for early-phase transcription, P7 is partially accessible to the Mabs, indicating that the nucleocapsid shell (protein P8) has undergone partial disassembly exposing the protein’s antigenic sites