1,117 research outputs found
Barley yellow striate mosaic-virus in the salivary glands of its planthopper vector Laodelphax striatellus Fallén
The salivary glands of planthoppers, Laodelphax striatellus, transmitting barley yellow striate mosaic virus (BYSMV), cryptogram */*:*/*:U/U:S,I/Au, were sectioned and examined in the electron microscope. BYSMV was detected in the cytoplasm but not in the nuclei or other organelles of infected cells which did not show structural changes. The BYSMV virions, 300 to 320 nm long and about 40 nm wide, were frequently arranged in parallel aggregates bound by a membrane. Long flexuous tubules of variable length, 18 to 20 nm wide were found in close association with BYSMV. The tubules were typically found in bundles surrounded by a membrane which also contained virus particles in different stages of organization. The virion of BYSMV is believed to consist of two coaxial helices, the inner derived from the tubules and the outer being formed between the inner helix and the outer envelope of the virus. A hypothesis is advanced for the morphogenesis of BYSMV in insect tissue which differs from that occurring in plants
Virus aggregates and pinwheels in plants infected with mite-transmitted ryegrass mosaic virus
Mulligan (1960) reported that ryegrass mosaic virus (RMV) had long rod-shaped particles that were often broken in preparation. Brandes (1964) confirmed the particle shape and determined a modal length of 703 nm and Brandes & Bercks (1965) placed RMV in the potato virus S group together with another mite-transmitted virus, wheat streak mosaic (WSMV), because their particles were slightly shorter and stiffer than those classified with potato virus Y. Shepard & Carroll (1967) found pinwheel inclusions, thought typical of the PVY group (Edwardson, 1966), in wheat infected by WSMV. Gibbs (1969) suggested that WSMV and RMV should be placed in a subgroup of the PVY group.
We maintained RMV in the glasshouse by mechanical inoculation to Italian ryegrass (Lolium multiflorum) cv. S. 22 and oats (Avena sativa) cv. Blenda. It was distinguished from other grass viruses by particle size and morphology, host range and vector transmission, as described by Catherall (1970)
Fixation and electron microscopy of the Rothamsted culture of henbane mosaic virus
Thin sections of tissue infected by viruses of the potato virus Y (PVY) group often fail to show virus particles. Henbane mosaic virus (HMV) is more concentrated in infected tissue than most PVY group viruses and seemed a suitable subject for electron microscopy. We failed to detect any particles after tissues were subjected to a commonly used double fixation technique but found them in tissue fixed with osmic acid; parallel results were found when purified virus preparations were similarly treated.
This paper reports some details of the fine structure of infected tissue and the effect of fixation on virus within the host cell and in purified preparations.
The Rothamsted culture of HMV used has been maintained in Nicotiana tabacum, cv. White Burley, usually infected by mechanical inoculation but occasionally with aphids. The virus was purified from this host by a modification of Damirdagh & Shepherd's (1970) procedure using borate instead of phosphate buffer throughout, and infectivity was confirmed by inoculation on Nicotiana sylvestris
Spin-Orbit Coupling in Iridium-Based 5d Compounds Probed by X-ray Absorption Spectroscopy
We have performed x-ray absorption spectroscopy (XAS) measurements on a
series of Ir-based 5d transition metal compounds, including Ir, IrCl3, IrO2,
Na2IrO3, Sr2IrO4, and Y2Ir2O7. By comparing the intensity of the "white-line"
features observed at the Ir L2 and L3 absorption edges, it is possible to
extract valuable information about the strength of the spin-orbit coupling in
these systems. We observe remarkably large, non-statistical branching ratios in
all Ir compounds studied, with little or no dependence on chemical composition,
crystal structure, or electronic state. This result confirms the presence of
strong spin-orbit coupling effects in novel iridates such as Sr2IrO4, Na2IrO3,
and Y2Ir2O7, and suggests that even simple Ir-based compounds such as IrO2 and
IrCl3 may warrant further study. In contrast, XAS measurements on Re-based 5d
compounds, such as Re, ReO2, ReO3, and Ba2FeReO6, reveal statistical branching
ratios and negligible spin-orbit coupling effects.Comment: 9 pages, 4 figure
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Developing a serocorrelate of protection against invasive group B streptococcus disease in pregnant women: a feasibility study.
BACKGROUND: Group B streptococcus is the leading cause of infection in infants. Currently, intrapartum antibiotic prophylaxis is the major strategy to prevent invasive group B streptococcus disease. However, intrapartum antibiotic prophylaxis does not prevent maternal sepsis, premature births, stillbirths or late-onset disease. Maternal vaccination may offer an alternative strategy. Multivalent polysaccharide protein conjugate vaccine development is under way and a serocorrelate of protection is needed to expedite vaccine licensure. OBJECTIVES: The ultimate aim of this work is to determine the correlate of protection against the major group B streptococcus disease-causing serotypes in infants in the UK. The aim of this feasibility study is to test key operational aspects of the study design. DESIGN: Prospective cohort study of pregnant women and their infants in a 6-month period (1 July to 31 December 2018). SETTING: Five secondary and tertiary hospitals from London and South England. National iGBS disease surveillance was conducted in all trusts in England and Wales. PARTICIPANTS: Pregnant women aged â„â18 years who were delivering at one of the selected hospitals and who provided consent during the study period. There were no exclusion criteria. INTERVENTIONS: No interventions were performed. MAIN OUTCOME MEASURES: (1) To test the feasibility of collecting serum at delivery from a large cohort of pregnant women. (2) To test the key operational aspects for a proposed large serocorrelates study. (3) To test the feasibility of collecting samples from those with invasive group B streptococcus. RESULTS: A total of 1823 women were recruited during the study period. Overall, 85% of serum samples were collected at three sites collecting only cord blood. At the two sites collecting maternal, cord and infant blood samples, the collection rate was 60%. A total of 614 women were screened for group B streptococcus with a colonisation rate of 22% (serotype distribution: 30% III, 25% Ia, 16% II, 14% Ib, 14% V and 1% IV). A blood sample was collected from 34 infants who were born to colonised women. Maternal and infant blood and the bacterial isolates for 15 newborns who developed invasive group B streptococcal disease during the study period were collected (serotype distribution: 29% III, 29% II, 21% Ia, 7% Ib, 7% IV and 7% V). LIMITATIONS: Recruitment and sample collection were dependent on the presence of research midwives rather than the whole clinical team. In addition, individualised consent limited the number of women who could be approached each day, and site set-up for the national surveillance study and the limited time period of this feasibility study limited recruitment of all eligible participants. CONCLUSIONS: We have verified the feasibility of collecting and processing rectovaginal swabs and blood samples in pregnant women, as well as samples from those with invasive group B streptococcal disease. We have made recommendations for the recruitment of cases within the proposed GBS3 study and for controls both within GBS3 and as an extension of this feasibility study. FUTURE WORK: A large case-control study comparing specific immunoglobulin G levels in mothers whose infants develop invasive group B streptococcal disease with those in colonised mothers whose infants do not develop invasive group B streptococcal disease is recommended. TRIAL REGISTRATION: Current Controlled Trials ISRCTN49326091; IRAS project identification number 246149/REC reference number 18/WM/0147. FUNDING: This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 23, No. 67. See the NIHR Journals Library website for further project information
The analysis of acetaminophen (paracetamol) and seven metabolites in rat, pig and human plasma by U(H)PLCâMS
A U(H)PLCâMS/MS method is described for the analysis of acetaminophen and its sulphate, glucuronide, glutathione, cysteinyl and N-acetylcysteinyl metabolites in plasma using stable isotope-labeled internal standards. P-Aminophenol glucuronide and 3-methoxyacetaminophen were monitored and semi-quantified using external standards. The assay takes 7.5 min/sample, requires only 5 ÎŒl of plasma and involves minimal sample preparation. The method was validated for rat plasma and cross validated for human and pig plasma and mouse serum. LOQ in plasma for these analytes were 0.44 ÎŒg/ml (APAP-C), 0.58 ÎŒg/ml (APAP-SG), 0.84 ÎŒg/ml (APAP-NAC), 2.75 ÎŒg/ml (APAP-S), 3.00 ÎŒg/ml (APAP-G) and 16 ÎŒg/ml (APAP). Application of the method is illustrated by the analysis of plasma following oral administration of APAP to male Han Wistar rats
The analysis of acetaminophen (paracetamol) and seven metabolites in rat, pig and human plasma by U(H)PLCâMS
A U(H)PLCâMS/MS method is described for the analysis of acetaminophen and its sulphate, glucuronide, glutathione, cysteinyl and N-acetylcysteinyl metabolites in plasma using stable isotope-labeled internal standards. P-Aminophenol glucuronide and 3-methoxyacetaminophen were monitored and semi-quantified using external standards. The assay takes 7.5 min/sample, requires only 5 ÎŒl of plasma and involves minimal sample preparation. The method was validated for rat plasma and cross validated for human and pig plasma and mouse serum. LOQ in plasma for these analytes were 0.44 ÎŒg/ml (APAP-C), 0.58 ÎŒg/ml (APAP-SG), 0.84 ÎŒg/ml (APAP-NAC), 2.75 ÎŒg/ml (APAP-S), 3.00 ÎŒg/ml (APAP-G) and 16 ÎŒg/ml (APAP). Application of the method is illustrated by the analysis of plasma following oral administration of APAP to male Han Wistar rats
Effects of sowing date and insecticides on cereal aphid populations and barley yellow dwarf virus on barley in Kenya
The effects of the date of sowing and insecticide sprays on aphid populations and barley yellow dwarf virus (BYDV) incidence in barley was studied in Mau Narok, Kenya. Rhopalosiphum padi (L.) and Metopolophium dirhodum (WLK.) were common aphid species, but other cereal aphids present were Rhopalosiphum maidis (Fitch), Stiobion avenae (F.), Schizaphis grammum (Rond.) and Hysteroneura setaria Thom. The incidence of BYDV was significantly decreased in plots sown with seed that had been treated with imidacloprid (NTNâ33893, Gaucho) and subsequently sprayed with foliar insecticide (Cypermethrin). Yield loss due to BYDV was also significantly different between the treatments and between the earlyplanted and the lateâplanted crop (P < 0.05). Grain yield and 1000âgrain weight were not significantly different among insecticide treatments in the earlyâplanted crop. In the lateâplanted crop, the yield increase with seed treatment alone was highly significant (P < 0.001), with a yield increase of 36â43%, more than that of the untreated control. Grain yield was significantly (P < 0.05) negatively correlated with the total number of cereal aphids. as well as with the numbers of R. padi alone
The relative contribution of climate to changes in lesser prairie-chicken abundance
Citation: Ross, B. E., Haukos, D., Hagen, C., & Pitman, J. (2016). The relative contribution of climate to changes in lesser prairie-chicken abundance. Ecosphere, 7(6), 11. doi:10.1002/ecs2.1323Managing for species using current weather patterns fails to incorporate the uncertainty associated with future climatic conditions; without incorporating potential changes in climate into conservation strategies, management and conservation efforts may fall short or waste valuable resources. Understanding the effects of climate change on species in the Great Plains of North America is especially important, as this region is projected to experience an increased magnitude of climate change. Of particular ecological and conservation interest is the lesser prairie-chicken (Tympanuchus pallidicinctus), which was listed as "threatened" under the U.S. Endangered Species Act in May 2014. We used Bayesian hierarchical models to quantify the effects of extreme climatic events (extreme values of the Palmer Drought Severity Index [PDSI]) relative to intermediate (changes in El Nino Southern Oscillation) and long-term climate variability (changes in the Pacific Decadal Oscillation) on trends in lesser prairie-chicken abundance from 1981 to 2014. Our results indicate that lesser prairie-chicken abundance on leks responded to environmental conditions of the year previous by positively responding to wet springs (high PDSI) and negatively to years with hot, dry summers (low PDSI), but had little response to variation in the El Nino Southern Oscillation and the Pacific Decadal Oscillation. Additionally, greater variation in abundance on leks was explained by variation in site relative to broad-scale climatic indices. Consequently, lesser prairie-chicken abundance on leks in Kansas is more strongly influenced by extreme drought events during summer than other climatic conditions, which may have negative consequences for the population as drought conditions intensify throughout the Great Plains
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