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64,543 result(s) for "Drummond, S"
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Optimization and Benchmarking of RT-LAMP-CRISPR-Cas12a for the Detection of SARS-CoV-2 in Saliva
Resource-limited settings and supply chain difficulties faced throughout the COVID-19 pandemic prompted the development of rapid and alternative methods of detecting SARS-CoV-2. These methods include reverse-transcription loop-mediated isothermal amplification (RT-LAMP), reverse-transcription recombinase polymerase amplification (RT-RPA), and CRISPR-Cas12a fluorescence detection. We describe RT-LAMP, RT-RPA, and CRISPR-Cas12a assays for the detection of the N and E-gene amplicons of SARS-CoV-2 and the optimization of various assay components, including incubation temperatures, Cas12a enzymes, reporter molecules, and the use of a lyophilized RT-LAMP master mix. We also describe the testing of a one-tube RT-LAMP-CRISPR-Cas12a assay. The one-tube assay showed promise in reducing hands-on time and improving time-to-result. We found no improvements in assay sensitivity with RT-RPA, but did achieve detection at a lower copy number with the lyophilized RT-LAMP master mix compared to liquid reagent (50 vs. 100 copies at 20 min). When used to detect the presence of SARS-CoV-2 RNA in clinical saliva samples from 75 infected patients, the discriminatory ability of the optimized RT-LAMP-CRISPR Cas12a assay was found to be comparable with RT-qPCR, with a minor reduction in sensitivity.
Comparison of precision and conventional irrigation management of cotton and impact of soil texture
Soil textural variability diminishes the effectiveness of conventional irrigation management. Variable rate irrigation (VRI) can address soil variability; however, users need guidance to prepare prescriptions for optimal water application. A study was conducted at Portageville, MO, USA, in 2016 and 2017 with the objective to compare yield and irrigation water use efficiency among three water-management treatments for cotton: rainfed, irrigated based on the USDA-ARS Irrigation Scheduling Supervisory Control And Data Acquisition (ISSCADA) system, and irrigated based on a water balance method. Sand content in the top 533 mm soil layer was estimated from apparent electrical conductivity (ECa). Yield values measured near an ECa observation were averaged to create a data set containing sand content and associated yield. Although the trend was for the rainfed treatment to have the lowest yield in both years, the yield differences among all treatments were not significant when sand content was not considered. A strong effect of sand content on cotton yield was observed in both seasons, although the slopes differed among the water management treatments in 2016. The ISSCADA system tended to have a higher irrigation water use efficiency in both seasons, but the difference was not significant in 2016 when total irrigation applications were low. The study is continuing at Portageville and other locations and the ISSCADA system is constantly being improved to better meet the needs of agricultural producers.
Network-based Responses to the Psychomotor Vigilance Task during Lapses in Adolescents after Short and Extended Sleep
Neuroimaging studies of the Psychomotor Vigilance Task (PVT) have revealed brain regions involved in attention lapses in sleep-deprived and well-rested adults. Those studies have focused on individual brain regions, rather than integrated brain networks, and have overlooked adolescence, a period of ongoing brain development and endemic short sleep. This study used functional MRI (fMRI) and a contemporary analytic approach to assess time-resolved peri-stimulus response of key brain networks when adolescents complete the PVT, and test for differences across attentive versus inattentive periods and after short sleep versus well-rested states. Healthy 14–17-year-olds underwent a within-subjects randomized protocol including 5-night spans of extended versus short sleep. PVT was performed during fMRI the morning after each sleep condition. Event-related independent component analysis (eICA) identified coactivating functional networks and corresponding time courses. Analysis of salient time course characteristics tested the effects of sleep condition, lapses, and their interaction. Seven eICA networks were identified supporting attention, executive control, motor, visual, and default-mode functions. Attention lapses, after either sleep manipulation, were accompanied by broadly increased response magnitudes post-stimulus and delayed peak responses in some networks. Well-circumscribed networks respond during the PVT in adolescents, with timing and intensity impacted by attentional lapses regardless of experimentally shortened or extended sleep.
The Effects of Total Sleep Deprivation on Cerebral Responses to Cognitive Performance
We review the findings from a study utilizing functional magnetic resonance imaging (FMRI) to examine the effects of total sleep deprivation (TSD) on verbal learning, arithmetic, and divided attention. For verbal learning and divided attention, TSD was associated with increased activation in the bilateral prefrontal cortex and parietal lobes. Increased sleepiness after TSD and lower levels of memory impairment were correlated with increased activation in specific regions of the prefrontal cortex and parietal lobes, respectively. The arithmetic task led to significantly decreased activation in the bilateral prefrontal cortex and parietal lobes. Based on this and other data, we hypothesize an adaptive cerebral response during cognitive performance following TSD with the specific pattern of adaptation depending on the specific cognitive processes performed. We discuss the need to test the hypothesis in a variety of ways.
Mutant Prolactin Receptor and Familial Hyperprolactinemia
The authors report cases of familial hyperprolactinemia due to a germline, loss-of-function mutation resulting in prolactin insensitivity. It appears to be caused by a heterozygous mutation in the prolactin receptor gene, PRLR . Prolactin, a hormone that is secreted predominantly by lactotrophs in the anterior pituitary gland, is required for the induction and maintenance of lactation in the peripartum and postpartum periods. 1 However, hyperprolactinemia unrelated to pregnancy occurs in approximately 0.1 to 0.3% of the general population 2 , 3 and may result in infertility, hypogonadism, and galactorrhea. Such nonphysiologic hyperprolactinemia is caused mainly by drugs or by tumors in the anterior pituitary gland, which are usually identifiable by means of magnetic resonance imaging (MRI). Approximately 50% of cases of nonphysiologic hyperprolactinemia are due to prolactinomas 4 ; a smaller percentage is due to lesions in . . .
Petunia hybrida CAROTENOID CLEAVAGE DIOXYGENASE7 Is Involved in the Production of Negative and Positive Branching Signals in Petunia
One of the key factors that defines plant form is the regulation of when and where branches develop. The diversity of form observed in nature results, in part, from variation in the regulation of branching between species. Two CAROTENOID CLEAVAGE DIOXYGENASE (CCD) genes, CCD7 and CCD8, are required for the production of a branch-suppressing plant hormone. Here, we report that the decreased apical dominance3 (dad3) mutant of petunia (Petunia hybrida) results from the mutation of the PhCCD7 gene and has a less severe branching phenotype than mutation of PhCCD8 (dad1). An analysis of the expression of this gene in wild-type, mutant, and grafted petunia suggests that in petunia, CCD7 and CCD8 are coordinately regulated. In contrast to observations in Arabidopsis (Arabidopsis thaliana), ccd7ccd8 double mutants in petunia show an additive phenotype. An analysis using dad3 or dad1 mutant scions grafted to wild-type rootstocks showed that when these plants produce adventitious mutant roots, branching is increased above that seen in plants where the mutant roots are removed. The results presented here indicate that mutation of either CCD7 or CCD8 in petunia results in both the loss of an inhibitor of branching and an increase in a promoter of branching.
Long-term impact of a precision agriculture system on grain crop production
Research is lacking on the long-term impacts of field-scale precision agriculture practices on grain production. Following more than a decade (1993–2003) of yield and soil mapping and water quality assessment, a multi-faceted, ‘precision agriculture system’ (PAS) was implemented from 2004 to 2014 on a 36-ha field in central Missouri. The PAS targeted management practices that address crop production and environmental issues. It included no-till, cover crops, growing winter wheat ( Triticum aestivum L.) instead of corn ( Zea mays L.) for field areas where corn was not profitable, site-specific N for wheat and corn using canopy reflectance sensing, variable-rate P, K and lime using intensively grid-sampled data, and targeting of herbicides based on weed pressure. The PAS assessment was accomplished by comparing it to the previous decade of conventional, whole-field corn-soybean ( Glycine max L.) mulch-tillage management. In the northern part of the field and compared to pre-PAS corn, relative grain yield of wheat in PAS was greatly improved and temporal yield variation was reduced on shallow topsoil, but relative grain yield was reduced on deep soil in the drainage channel. In the southern part of the field where corn remained in production, PAS did not lead to increased yield, but temporal yield variation was reduced. Across the whole field, soybean yield and temporal yield variation were only marginally influenced by PAS. Spatial yield variation of all three crops was not altered by PAS. Therefore, the greatest production advantage of a decade of precision agriculture was reduced temporal yield variation, which leads to greater yield stability and resilience to changing climate.
Varying the expression pattern of the strigolactone receptor gene DAD2 results in phenotypes distinct from both wild type and knockout mutants
The action of the petunia strigolactone (SL) hormone receptor DAD2 is dependent not only on its interaction with the PhMAX2A and PhD53A proteins, but also on its expression patterns within the plant. Previously, in a yeast-2-hybrid system, we showed that a series of a single and double amino acid mutants of DAD2 had altered interactions with these binding partners. In this study, we tested the mutants in two plant systems, Arabidopsis and petunia. Testing in Arabidopsis was enabled by creating a CRISPR-Cas9 knockout mutant of the Arabidopsis strigolactone receptor (AtD14). We produced SL receptor activity in both systems using wild type and mutant genes; however, the mutants had functions largely indistinguishable from those of the wild type. The expression of the wild type DAD2 from the CaMV 35S promoter in dad2 petunia produced plants neither quite like the dad2 mutant nor the V26 wild type. These plants had greater height and leaf size although branch number and the plant shape remained more like those of the mutant. These traits may be valuable in the context of a restricted area growing system such as controlled environment agriculture.
DWARF27 and CAROTENOID CLEAVAGE DIOXYGENASE 7 genes regulate release, germination and growth of gemma in Marchantia polymorpha
Strigolactones (SLs), a class of carotenoid-derived hormones, play a crucial role in flowering plants by regulating underground communication with symbiotic arbuscular mycorrhizal fungi (AM) and controlling shoot and root architecture. While the functions of core SL genes have been characterized in many plants, their roles in non-tracheophyte plants like liverworts require further investigation. In this study, we employed the model liverwort species Marchantia polymorpha , which lacks detectable SL production and orthologs of key SL biosynthetic genes, including CAROTENOID CLEAVAGE DIOXYGENASE 8 ( CCD8 ) and MORE AXILLARY GROWTH 1 ( MAX1 ). However, it retains some SL pathway components, including DWARF27 ( D27 ) and CCD7 . To help elucidate the function of these remaining components in M. polymorpha , knockout mutants were generated for MpD27–1 , MpD27–2 and MpCCD7 . Phenotypic comparisons of these mutants with the wild-type control revealed a novel role for these genes in regulating the release of gemmae from the gemma cup and the germination and growth of gemmae in the dark. Mpd27–1 , Mpd27–2 , and Mpccd7 mutants showed lower transcript abundance of genes involved in photosynthesis, such as EARLY LIGHT INDUCED ( ELI ), and stress responses such as LATE EMBRYOGENESIS ABUNDANT ( LEA ) but exhibited higher transcript levels of ETHYLENE RESPONSE FACTORS ( ERFs ) and SL and carotenoid related genes, such as TERPENE SYNTHASE ( TS ), CCD7 and LECITHIN-RETINAL ACYL TRANSFERASE (LRAT) . Furthermore, the mutants of M. polymorpha in the SL pathway exhibited increased contents of carotenoid. This unveils a previously unrecognized role for MpD27–1, MpD27–2 and MpCCD7 in controlling release, germination, and growth of gemmae in response to varying light conditions. These discoveries enhance our comprehension of the regulatory functions of SL biosynthesis genes in non-flowering plants.
Incidence of periorbital necrotising fasciitis in the UK population: a BOSU study
Background Periorbital necrotising fasciitis (PNF) is a devastating infection of subcutaneous soft tissue and underlying fascia causing severe morbidity and even loss of life. Few case reports of PNF exist and there are no prospective epidemiological studies. Methods A prospective observational study was undertaken using the British Ophthalmological Surveillance Unit reporting system. Questionnaires were sent to reporting ophthalmologists in the UK seeking cases of PNF over a 2-year period. Results 30 new cases were confirmed. 16 of the reported cases followed a precipitating event, 9 cases followed trauma and 3 followed surgery. β-haemolytic Streptococcus A was the causative organism identified in 76%, either alone or with concurrent infection, and antibiotic sensitivities are discussed. Systemic complications occurred in the majority of cases (66.6%), with sepsis and death occurring in 10%. Over 50% of surviving patients had subsequent morbidity, reduced acuity (<6/18) being common. Conclusion PNF is a rare, dangerous condition. This study identified an incidence of 0.24 per 1 000 000 per annum in the UK. β-haemolytic Streptococcus A is the most common causative organism. Mortality remains a potential outcome, and survivors suffer significant morbidity. Early intravenous antibiotic management with a consensus favouring penicillin and clindamycin combined with debridement.