IL-1α Signaling Is Critical for Leukocyte Recruitment after Pulmonary Aspergillus fumigatus Challenge

Aspergillus fumigatus is a mold that causes severe pulmonary infections. Our knowledge of how A. fumigatus growth is controlled in the respiratory tract is developing, but still limited. Alveolar macrophages, lung resident macrophages, and airway epithelial cells constitute the first lines of defense against inhaled A. fumigatus conidia. Subsequently, neutrophils and inflammatory CCR2+ monocytes are recruited to the respiratory tract to prevent fungal growth. However, the mechanism of neutrophil and macrophage recruitment to the respiratory tract after A. fumigatus exposure remains an area of ongoing investigation. Here we show that A. fumigatus pulmonary challenge induces expression of the inflammasome-dependent cytokines IL-1β and IL-18 within the first 12 hours, while IL-1α expression continually increases over at least the first 48 hours. Strikingly, Il1r1-deficient mice are highly susceptible to pulmonary A. fumigatus challenge exemplified by robust fungal proliferation in the lung parenchyma. Enhanced susceptibility of Il1r1-deficient mice correlated with defects in leukocyte recruitment and anti-fungal activity. Importantly, IL-1α rather than IL-1β was crucial for optimal leukocyte recruitment. IL-1α signaling enhanced the production of CXCL1. Moreover, CCR2+ monocytes are required for optimal early IL-1α and CXCL1 expression in the lungs, as selective depletion of these cells resulted in their diminished expression, which in turn regulated the early accumulation of neutrophils in the lung after A. fumigatus challenge. Enhancement of pulmonary neutrophil recruitment and anti-fungal activity by CXCL1 treatment could limit fungal growth in the absence of IL-1α signaling. In contrast to the role of IL-1α in neutrophil recruitment, the inflammasome and IL-1β were only essential for optimal activation of anti-fungal activity of macrophages. As such, Pycard-deficient mice are mildly susceptible to A. fumigatus infection. Taken together, our data reveal central, non-redundant roles for IL-1α and IL-1β in controlling A. fumigatus infection in the murine lung

Heat Tolerance of Kentucky Bluegrasses, Perennial Ryegrasses, and Annual Bluegrass

Use of cool-season turfgrasses in transitional environments is limited, in part, by their heat tolerance. Development of a rapid heat tolerance screening technique would be of value in determining the potential of turf•grasses for use in warmer areas. The heat tolerance of 22 Kentucky bluegrass (Poa pratensis L.) cultivars, Poa annua L., and four perennial ryegrass cultivars (Lolium perenne L.) was evaluated by exposing plants for 30 min to temperatures ranging from 41 to 49 C in single degree intervals. Ten-week-old plants, which had been grown under a low level of N fertilization and watered infrequently to maximize heat tolerance development, were sealed in plastic bags, placed in a constant temperature water bath for treatment, and then replanted. Recovery was evaluated by visually rating the plants 4 weeks after treatment or by harvesting and weighing plants 2 weeks after treatment and expressing the weight as a percentage of the weight of a non-stressed control (referred to as recovery weight). Cultivar comparisons were based on the average recovery weight over a given temperature range. Initial injury occurred at 41 to 43 C with complete kill at 47 to 49 C. Kentucky bluegrass was more heat tolerant than Poa annua L. and perennial ryegrass. Heat tolerance of the latter two species was approximately equal. The Kentucky bluegrass cultivars tested were similar in heat tolerance. Among the ryegrasses, \u27Loretta\u27 was less heat tolerant than \u27Diplomat\u27, \u27Pennfine\u27, and \u27Citation\u27. Of all the grasses, \u27Sydsport\u27 Kentucky bluegrass ranked the highest and Loretta perennial ryegrass the lowest in heat tolerance. The correlation between dilute acid extractable carbohydrate reserves and recovery weight for these five cultivars was not significant. There was a significant negative correlation between recovery weight and Fe and Al concentration

Heat Stress Effects on Protein Synthesis and Exosmosis of Cell Solutes in Three Turfgrass Species

Kentucky bluegrass (Poa pratensis L.), annual bluegrass (Poa annua L.), and perennial ryegrass (Lolium perenne L.) differ in their heat tolerance as determined by plant dry weight 2 weeks after exposure to heat stress. The status of the plants at that time depends on the degree of injury that occurs during the stress treatment and the repair or tolerance of that injury. The purpose of this research was to evaluate species differences in the degree of initial injury due to heat stress. The incorporation of radio-labeled leucine as an indicator of the net rate of protein synthesis and the efflux of cell solutes from plant tissue sections into distilled water were evaluated immediately after turfgrass shoots or tissue sections were exposed to temperatures in the range of 43 to 51 °C for 30 min. Net protein synthesis in the grasses was very heat labile. Incorporation of radio-labeled leucine declined an average of 69% in plants previously heated at 43 °C compared to plants held at 27 °C. Efflux of cell solutes from the tissue sections did not increase in plants that had been heated to 43, 45, 47, or 49 °C compared to plants held at 25 °C. No significant differences were found between the grasses for the parameters tested. Either disruption of some other physiological process or differential repair or tolerance of the heat stress injury accounted for the heat tolerance rankings of the grasses. Also, the results of this study indicate that indirect rather than direct heat injury is responsible for the behavior of the grasses stressed at the temperatures and exposure periods used in this study

Separation of Kentucky Bluegrass Cultivars Using Peroxidase Isoenzyme Banding Patterns

The peroxidase isoenzyme banding pattern of 15 Kentucky bluegrass (Poa pratensis L.) cultivars was investigated for use in identification. Isoenzymes were separated by polyacrylamide slab gel electrophoresis, stained with benzidine-H2O2, and the relative intensities of the bands evaluated with a densitometer. Cultivar separations were made on single seedling samples at the 1% level of confidence using band number, mobility, and intensity ratios. Overall variability of the procedure was evaluated using a horseradish peroxidase standard and the effects of seedling age and seedlot determined. Of the 15 cultivars, 11 could be separated individually, whereas the remaining 4 were grouped into two pairs. Band mobilities for the standard and the cultivars varied 1 to 3%, whereas intensity ratios varied 9% for the standard, and 5 to 20% for most cultivars. Neither seedlot, seedling age, nor leaf position on the same seedling affected the peroxidase isoenzyme banding pattern

Effect of P, K, and Lime on Growth, Composition, and P Absorption by Merion Kentucky Bluegrass

Information is needed concerning the effects of different soil fertility levels on the activity of turfgrass roots in that part of the soil profile sampled for routine soil tests. In Pennsylvania, a sampling depth of 5 to 7.5 cm is suggested for established turf. A study was conducted on \u27Merion\u27 Kentucky bluegrass (Poa pratensis L.) to determine relationships among lime, phosphorus, and potassium applications; soil test results; foliar growth and elemental analysis; and root activity as determined by 32P uptake from three soil depths. In the field, soil pH values were 5.8 and 7.0, P ranged from 13 to 137 ppm, and K ranged from 0.14 to 0.43 meq./100g. Liming increased the Ca content in clippings from 0.35 to 0.42%. Phosphorus treatments increased P from 0.32 to 0.44%, and K was increased from 2.00 to 2.45% by K fertilization. Clipping yield was increased by P treatments. Sod plugs from the field were used in the greenhouse to determine root activity. Agar discs containing 32P were placed at a depth of 1.3, 3.8, or 6.4 cm, and the clippings were assayed for 32P after 20 and 33 days. Shallow placement of 32P resulted in more absorption. A soil P x depth interaction was found for 32P absorption. A significant positive correlation between soil P and 32P absorption was obtained for the 1.3 cm depth, whereas a nonsignificant correlation was found for the 6.4 cm placement. Results indicated that P enhanced rooting, and the magnitude of absorption from the 1.3-cm depth exemplified the need for P near the soil surface for optimum turf establishment