scholarly journals Ability of Euscelidius variegatus to Transmit Flavescence Dorée Phytoplasma with a Short Latency Period

Insects ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 603
Author(s):  
Luca Picciau ◽  
Bianca Orrù ◽  
Mauro Mandrioli ◽  
Elena Gonella ◽  
Alberto Alma
Keyword(s):  
Salivary Glands ◽  
Infection Rate ◽  
Temporal Dynamics ◽  
Latency Period ◽  
Flavescence Dorée ◽  
Access Period ◽  
Euscelidius Variegatus ◽  
Inoculation Access Period ◽  
Time Required

Phytoplasma transmission takes place by insect vectors through an Acquisition Access Period (AAP), Latency Period (LP) and Inoculation Access Period (IAP). Generally, phytoplasmas are believed to be transmitted more efficiently by nymphs because they need a long LP to reach the salivary glands before becoming infective. The transmission can start from adults as well, but in this case a long LP may exceed the insect’s lifespan. However, previous evidence has indicated that adults can undergo a shorter LP, even though little knowledge is available regarding the phytoplasma temporal dynamics during this period. Here, we investigate the minimum time required by the phytoplasma to colonize the vector midgut and salivary glands, and finally to be inoculated into a plant. We used the leafhopper Euscelidius variegatus to investigate the life cycle of flavescence dorée phytoplasma (FDP). Phytoplasma-free E. variegatus adults were left on broad beans (BBs) infected with FDP for an AAP of 7 days. Subsequently, they were individually transferred onto a healthy BB for seven different IAPs, each one lasting 24 h from day 8 to 14. Molecular analyses and fluorescence in situ hybridization were performed for FDP detection. FDP was found in the leafhopper midgut from IAP 1 with an infection rate reaching 50%, whereas in the salivary glands it was found from IAP 2 with an infection rate reaching 30%. FDP was also detected in BBs from IAP 4, with infection rates reaching 10%. Our results represent an important step to further deepen the knowledge of phytoplasma transmission and its epidemiology.

scholarly journals Immunolabeling of grapevine flavescence dorée MLO in salivary glands of Euscelidius variegatus: a light and electron microscopy study.

1990 ◽  
Vol 38 (1) ◽  
pp. 79-85 ◽  
Author(s):  
J Lherminier ◽  
G Prensier ◽  
E Boudon-Padieu ◽  
A Caudwell
Keyword(s):  
Light Microscopy ◽  
Salivary Glands ◽  
Light And Electron Microscopy ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Good Tool ◽  
Tissue Samples ◽  
Thin Sections ◽  
Flavescence Dorée ◽  
Euscelidius Variegatus

Flavescence dorée (FD), a grapevine yellows disease, is caused by a mycoplasma-like organism (MLO). A colloidal gold indirect immunolabeling technique identified MLO in salivary glands of a vector leafhopper, Euscelidius variegatus. After aldehyde fixation, tissue samples were prepared by cryoultramicrotomy or embedding in acrylic resins. Double fixation with aldehydes and osmium retroxide, followed by embedding in epon, was also performed. Thin or semi-thin serial sections were treated with polyclonal anti-FD-MLO rabbit antibodies, then with gold-conjugated anti-rabbit IgG. Labeling was revealed using the silver enhancement technique for light microscopy. MLO in frozen thin sections of glands were efficiently labeled. Optimal results were obtained with 4% paraformaldehyde-0.1% glutaraldehyde fixation and low-temperature embedding in LR White resin. Both scattered MLO and unusual dense forms of MLO were easily detected with the electron-dense gold probe. This method distinguished MLO from other membrane-limited bodies and provided a good tool for studying infection in large regions of FD-infected tissues by light microscopy.

scholarly journals Insect Injection and Artificial Feeding Bioassays to Test the Vector Specificity of Flavescence Dorée Phytoplasma

2006 ◽  
Vol 96 (7) ◽  
pp. 790-796 ◽  
Author(s):  
Alberto Bressan ◽  
Denis Clair ◽  
Olivier Sémétey ◽  
Elisabeth Boudon-Padieu
Keyword(s):  
Pcr Amplification ◽  
Insect Species ◽  
Flavescence Dorée ◽  
The Family ◽  
Euscelidius Variegatus ◽  
Vector Specificity ◽  
Inoculation Access Period ◽  
Hemipteran Insect ◽  
Polymerase Chain ◽  
Vector Competency

The specificity of vector transmission of Flavescence dorée phytoplasma (FDP) was tested by injecting FDP, extracted from laboratory-reared infective Euscelidius variegatus, into specimens of 15 other hemipteran insect species collected in European vineyards. Concentrations of viable phytoplasma extracts and latency in vectors were monitored by injection of healthy-reared E. variegatus leafhoppers. Based on these preliminary results, insects were injected by using phytoplasma extracts that ensured the highest rate of FDP acquisition and transmission by E. variegatus. Transmission into an artificial diet through a Parafilm membrane about 3 weeks after insect injection was attempted. FDP-injected insects that belonged to 15 hemipteran species were confined in cages and fed through the membrane for a 4- to 5-day inoculation access period. FDP DNA was detected by polymerase chain reaction (PCR) in the feeding buffer fed upon by Anoplotettix fuscovenosus, Aphrodes makarovi,E. variegatus, and Euscelis incisus. PCR amplification with specific primers detected FDP DNA in injected insects of all test insect species. Band intensity was positively correlated with the transmissibility of FDP. Transmission of FDP to plants by feeding was confirmed for Anoplotettix fuscovenosus, E. variegatus, and Euscelis incisus, but not for Aphrodes makarovi. Our results suggest that vector competency of FDP is restricted to specimens belonging to the family Cicadellidae, subfamily Deltocephalinae.

scholarly journals Interactions between the flavescence dorée phytoplasma and its insect vector indicate lectin-type adhesion mediated by the adhesin VmpA

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Nathalie Arricau-Bouvery ◽  
Sybille Duret ◽  
Marie-Pierre Dubrana ◽  
Delphine Desqué ◽  
Sandrine Eveillard ◽  
...  
Keyword(s):  
Salivary Glands ◽  
Insect Cell ◽  
Insect Cell Line ◽  
Insect Vector ◽  
Flavescence Dorée ◽  
Salivary Gland Cells ◽  
Scaphoideus Titanus ◽  
Euscelidius Variegatus ◽  
Natural Vector ◽  
Insect Gut

AbstractThe flavescence dorée phytoplasma undergoes a propagative cycle in its insect vectors by first interacting with the insect cell surfaces, primarily in the midgut lumen and subsequently in the salivary glands. Adhesion of flavescence dorée phytoplasma to insect cells is mediated by the adhesin VmpA. We hypothesize that VmpA may have lectin-like activity, similar to several adhesins of bacteria that invade the insect gut. We first demonstrated that the luminal surface of the midgut and the basal surface of the salivary gland cells of the natural vector Scaphoideus titanus and those of the experimental vector Euscelidius variegatus were differentially glycosylated. Using ELISA, inhibition and competitive adhesion assays, and protein overlay assays in the Euva-6 insect cell line, we showed that the protein VmpA binds insect proteins in a lectin-like manner. In conclusion, the results of this study indicate that N-acetylglucosamine and mannose present on the surfaces of the midgut and salivary glands serve as recognition sites for the phytoplasma adhesin VmpA.

scholarly journals Global soil moisture data derived through machine learning trained with in-situ measurements

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Sungmin O. ◽  
Rene Orth
Keyword(s):  
Machine Learning ◽  
Soil Moisture ◽  
Large Scale ◽  
Short Term Memory ◽  
Temporal Dynamics ◽  
Soil Moisture Data ◽  
Wide Range ◽  
Global Soil

AbstractWhile soil moisture information is essential for a wide range of hydrologic and climate applications, spatially-continuous soil moisture data is only available from satellite observations or model simulations. Here we present a global, long-term dataset of soil moisture derived through machine learning trained with in-situ measurements, SoMo.ml. We train a Long Short-Term Memory (LSTM) model to extrapolate daily soil moisture dynamics in space and in time, based on in-situ data collected from more than 1,000 stations across the globe. SoMo.ml provides multi-layer soil moisture data (0–10 cm, 10–30 cm, and 30–50 cm) at 0.25° spatial and daily temporal resolution over the period 2000–2019. The performance of the resulting dataset is evaluated through cross validation and inter-comparison with existing soil moisture datasets. SoMo.ml performs especially well in terms of temporal dynamics, making it particularly useful for applications requiring time-varying soil moisture, such as anomaly detection and memory analyses. SoMo.ml complements the existing suite of modelled and satellite-based datasets given its distinct derivation, to support large-scale hydrological, meteorological, and ecological analyses.

In situ enzymatic removal of orthophosphate by the nucleoside phosphorylase catalyzed phosphorolysis of nicotinamide riboside

1982 ◽  
Vol 60 (9) ◽  
pp. 917-921 ◽  
Author(s):  
John W. Shriver ◽  
Brian D. Sykes
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nucleoside Phosphorylase ◽  
Nicotinamide Riboside ◽  
Time Required ◽  
Removal System ◽  
Nuclear Magnetic

An enzymatic orthophosphate removal system is described which can be effectively used to continuously remove orthophosphate from biochemical samples. The phosphorolysis of nicotinamide riboside is catalyzed by calf spleen nucleoside phosphorylase to give ribose-1-PO4 and nicotinamide along with a proton. At pH 8 the production of ribose-1-PO4 from orthophosphate is essentially quantitative. This reaction can be monitored optically or by 31P nuclear magnetic resonance (NMR). Equations are given for determining the time required to remove a given amount of phosphate from a typical NMR sample with a known amount of nucleoside phosphorylase. The effects of a competing orthophosphate-producing reaction are considered.

Age grades and infection rates of Rhipicephalus appendiculatus Neumann (Acari: Ixodidae) to assess theileriosis challenge in the field

1985 ◽  
Vol 75 (4) ◽  
pp. 653-660 ◽  
Author(s):  
Alan R. Walker ◽  
June D. Fletcher
Keyword(s):  
Salivary Glands ◽  
Infection Rate ◽  
Rhipicephalus Appendiculatus ◽  
Physiological Age ◽  
Methyl Green ◽  
Infection Rates ◽  
A Value ◽  
Type 3

AbstractData are presented from five series of 240 adults of Rhipicephalus appendiculatus Neumann kept in the laboratory, in which a steady decline in the numbers of granules in e cells of type 3 acini of the salivary glands occurred. This was readily detected in whole gland preparations of the salivary glands stained with methyl green and pyronin, and the same specimens could be used for detecting Theileria parasites in the salivary glands. Characteristics for grading these ticks into three physiological age grades are given, and a formula is provided for incorporating the age grade with infection rate. This gives a value for comparative estimates of the challenge posed by field populations of ticks for the transmission of Theileria to cattle.

Fate and transport of faecal contamination microbial indicators, pathogenic protozoa and Campylobacter in the artificially recharged fractured aquifer of Salento, Italy

2008 ◽  
Vol 57 (6) ◽  
pp. 849-856 ◽  
Author(s):  
R. La Mantia ◽  
C. Masciopinto ◽  
C. Levantesi ◽  
V. Tandoi
Keyword(s):  
Pathogenic Bacteria ◽  
Fate And Transport ◽  
Fractured Aquifer ◽  
Specific Detection ◽  
Microbial Indicators ◽  
Faecal Contamination ◽  
Time Required ◽  
Indicators Of Faecal Contamination ◽  
Campylobacter Spp

The study investigates the fate and transport of microorganisms introduced by artificial groundwater recharge at the Nardò fractured aquifer in Salento, Italy. Microbial indicators of faecal contamination, parasitic protozoa (Giardia and Cryptosporidium) and pathogenic bacteria (Campylobacter spp.), were monitored into injected water and groundwater to test the efficiency of the “natural disinfection” into the fractured aquifer. A remarkable decrease of microbial indicators and pathogens was observed suggesting that pathogens removal or inactivation may be possible during water flow in fractured aquifer. The recently described PNA probe CJE195 (Lehtola et al. 2005) was utilised for the rapid and specific detection of Campylobacter spp. by fluorescence in situ hybridization (FISH) after enrichment. FISH results were consistent with those of traditional cultural method (ISO 17995) applied in parallel: time required for Campylobacter identification was reduced of 4 days.

In-Situ, Time Resolved, Kinetics of Reactions in Co-Ge thin Films

1991 ◽  
Vol 237 ◽  
Author(s):  
R. M. Walser ◽  
Byung-Hak Lee ◽  
Alaka Valanju ◽  
Winston Win ◽  
M. F. Becker
Keyword(s):  
Depth Profiling ◽  
Laser Interferometry ◽  
Semiconductor Interface ◽  
Time Resolved ◽  
Interface Reactions ◽  
Valuable Adjunct ◽  
Diffusion Controlled ◽  
Sputter Deposited ◽  
Time Required

ABSTRACTWe report the first kinetic study of metal-semiconductor interface reactions using in-situ, time resolved, laser interferometry. Diffusion couples with Co/Ge thicknesses of 1500 Å/1500 Å were sputter deposited on silicon wafers, and vacuum-annealed at temperatures between 300°C-400°C. Under these conditions polycrystalline CoGe was expected to form [1]. Real time laser (HeNe 6328 Å) interferograms for each anneal were recorded in-situ. These data were supplemented by information from AES and X-ray.For temperatures below 400°C the diffusion controlled formation of CoGe was observed. The composition was confirmed by Auger depth profiling that showed uniform Co and Ge concentrations when the reaction went to completion. The well defined interferences fringes were formed by the dissolution of amorphous Ge. The activation energy = 1.6 eV for the formation of CoGe were determined with precision from the temperature dependence of the time required to anneal the fixed λ/4 distance between adjacent minima and maxima of the interferogram. We discuss the evidence for formation of an intermediate Co-rich compound following the initial diffusion of Co into Ge. The results of these experiments indicate that optical interferometry will be a valuable adjunct to other techniques used to study metal-semiconductor interface reactions.

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