RNA transcripts without obvious coding potential are widespread in many creatures, including the fruit fly, Drosophila melanogaster. Several noncoding RNAs have been identified within the Drosophila bithorax complex. These first appear in blastoderm stage embryos, and their expression patterns indicate that they are transcribed only from active domains of the bithorax complex. It has been suggested that these noncoding RNAs have a role in establishing active domains, perhaps by setting the state of Polycomb Response Elements A comprehensive survey across the proximal half of the bithorax complex has now revealed nine distinct noncoding RNA transcripts, including four within the Ultrabithorax transcription unit. At the blastoderm stage, the noncoding transcripts collectively span 75% of the 135 kb surveyed. Recombination-mediated cassette exchange was used to invert the promoter of one of the noncoding RNAs, a 23-kb transcript from the bxd domain of the bithorax complex. The resulting animals fail to make the normal bxd noncoding RNA and show no transcription across the bxd Polycomb Response Element in early embryos. The mutant flies look normal; the regulation of the bxd domain appears unaffected. Thus, the bxd noncoding RNA has no apparent function.
Athletic field safety is a top concern of field managers and athletic directors across all sports. Increased field usage on fields with traffic-sensitive cultivars results in reduced turf cover and therefore decreased field safety. Kentucky bluegrass (Poa pratensis L., KBG) is the most widely used cool-season turfgrass on athletic fields due to its dense turf canopy. While most KBG cultivars have strong recuperative potential, significant cultivar differences in ability to withstand athletic field traffic exist. This study was conducted to determine whether leaf epidermal cell sizes predict differences in KBG cultivar traffic tolerance. Upper epidermal cell size, lower epidermal cell size, and intercellular void space (IVS) were measured on three traffic-tolerant and three traffic-sensitive KBG cultivars from the 2011 National Turfgrass Evaluation Program KBG trial, arranged in a randomized complete block design with three replications. Transverse sections of leaf tissue were fixed in an acid/alcohol solution and embedded with paraffin prior to sectioning for imaging by light microscopy. Cell size was determined by counting cells per unit area from light microscopy images. Leaf upper and lower epidermal cell size was not a predictor of traffic tolerance. Differences were measured in IVS at the cultivar level and at the traffic-sensitive vs. traffic-tolerant grouping contrast level. Traffic-tolerant cultivars exhibited larger IVS (2823 μm 2) than traffic-sensitive cultivars (1112 μm 2). Further investigation of these leaf anatomy size theories in relation to athletic traffic tolerance should be conducted on more cultivars, including recently released commercially available genotypes.
Nitrogen source and rate effects on velvet bentgrass (Agrostis canina L.; VBG) putting greens are not well documented, particularly in the north central United States which has different conditions than areas where VBG is normally grown. Acidic soil pH is perceived as necessary for VBG; in nonacidic soils, acidifying fertilizers may provide better VBG quality than less or nonacidic fertilizers. We wanted to determine the effects of N sources representing a range of acidity and N rates (49, 146, 244 kg ha−1 yr−1) on VBG agronomic and playability characteristics when grown on alkaline soils. Fertilizer treatments were applied at 2‐wk intervals to ‘Vesper’ VBG putting greens using liquid forms of ammonium sulfate, urea, ammonium nitrate, and calcium nitrate. Separate trials were conducted on two root zones: an 80:20 sand/peat mixture (pH 7.8) and a Troxel silt loam (pH 7.0). Nitrogen source usually had negligible effects on turf characteristics, though occasionally calcium nitrate resulted in poorer quality or shoot density than other sources. Clipping yield, shoot density, and relative chlorophyll index increased, and ball roll distances decreased, as N rate increased. On sand, not even the 244 kg ha−1 yr−1 rate of N guaranteed acceptable turf quality. On silt loam, 146 kg ha−1 N yr−1 usually provided acceptable turf quality, though quality was occasionally improved at 244 kg ha−1 N yr−1 Velvet bentgrass suffered from mid‐summer stress alleviated by higher rather than lower quantities of N fertilizer.
Increased athletic field usage and growing understanding of injury prevention have sports turf managers interested in implementing management practices that will improve turfgrass traffic stress tolerance. Previous research has shown that other abiotic stressors, such as mowing/rolling, high/low temperature, and drought, result in changes to turfgrass antioxidant enzyme activity levels. This study was conducted to determine how simulated athletic traffic affects the magnitude and duration of changes in antioxidant enzyme activity of Kentucky bluegrass (Poa pratensis L.; KBG). Two levels of simulated athletic traffic (0 and 2 games week −1 ) were applied to a blend of 'True Blue HGT' KBG using a modified Baldree traffic simulator for 7 simulated traffic events (STEs) in each year coinciding with the 2018 and 2019 fall football schedule. One STE of two games wk −1 represents a high school field hosting junior varsity and varsity games each week. Experimental design was a split-plot randomized complete block with four replications. Turfgrass leaves were individually cut from sub-plots at 0, 2, 4, 8, 12, and 24 h after simulated traffic application to assay the activities of ascorbate peroxidase (APX), catalase (CAT), and superoxide dismutase (SOD). Traffic application resulted in decreased activity of APX by 30-45% in 2019, CAT by 26-28% in 2019, and SOD by 3-13% on some rating dates in 2018 and 2019. Activity of APX was lowest at 4-12 h after STE. Catalase and SOD activity was highest at 0 or 4 h after STEs in early 2019 but in late 2019 it was highest at 12 or 24 h after STEs. These results suggest that cumulative traffic stress increases the time required for antioxidant enzyme activity, directing future research to investigate timings and frequency of product application, potentially conferring protection to antioxidant enzymes.
Cassava bacterial blight disease was detected for the first time in Solomon Islands on Malaita Island. The bacterium was isolated from diseased cassava plants exhibiting typical leaf symptoms. Xanthomonas axonopodis pv. manihotis was identified using biochemical and molecular tests and confirmed as the causal agent by fulfilling Koch's postulates. This is the first record of this pathogen in the South Pacific.
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