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Since the mid-1950s, native pines in the San Bernardino Mountains (SBM) in southern California have shown symptoms of decline. Initial studies in 1963 showed that ozone (O3) generated in the upwind Los Angeles Basin was responsible for the injury and decline of sensitive trees. Ambient O3decreased significantly by the mid-1990s, resulting in decreased O3injury and improved tree growth. Increased growth of trees may also be attributed to elevated atmospheric nitrogen (N) deposition. Since most of the N deposition to mixed conifer forest stands in the SBM results from dry deposition of nitric acid vapor (HNO3) and ammonia (NH3), characterization of spatial and temporal distribution of these two pollutants has become essential. Although maximum daytime O3concentrations over last 40 years have significantly decreased (~3-fold), seasonal means have been reduced much less (~1.5-fold), with 2-week long means occasionally exceeding 100 ppb in the western part of the range. In the same area, significantly elevated concentrations of HNO3and NH3, up to 17.5 and 18.5 μg/m3as 2-week averages, respectively, have been determined. Elevated levels of O3and increased N deposition together with long-term drought predispose the SBM forests to massive bark beetle attacks making them susceptible to catastrophic fires.

Cette etude a ete realisee en 1989 et 1990 a Shirley Meadow dans le sud de la sierra Nevada en Californie. L'objectif consistait a evaluer les effets de l'ozone (O 3 ) sur la reponse physiologique et la croissance de semis de Pinus ponderosa Dougl. ex P. & C. Laws. (pin ponderosa). Les semis on ete exposes a trois niveaux de O 3 dans des chambres a ciel ouvert (air filtree au charbon de bois (CF), niveau ambiant de O 3 (1xO 3 ) ou deux fois le niveau ambiant de O 3 (2xO 3 ));les concentrations moyennes pour 24 h etaient respectivement de ∼20, ∼60 et ∼120 ppb. Au cours de la premiere saison de croissance, les aiguilles de l'annee chez les plants exposes a 2xO 3 ont subi des dommages plus prononces ainsi que des diminutions periodiques de la fluorescence chlorophyllienne et de la photosynthese nette, mais O 3 n'a eu aucun effet significatif sur la croissance. Au cours de la seconde saison de croissance, les aiguilles de 1 an exposees a 2xO 3 ont subi une reduction significative de leurs reponses physiologique et biochimique ainsi qu'une diminution de croissance comparativement aux plants exposes a CF et a 1xO 3 . Ces resultats laissent entrevoir la possibilite que O 3 cause une diminution insidieuse de la croissance chez les semis de pin ponderosa apres plusieurs saisons de croissance successives.

Atmospheric dry deposition to branches of Pinus contorta and P. albicaulis was measured during summer 1987 in a sub-alpine zone at Eastern Brook Lake Watershed (EBLW), eastern Sierra Nevada, California. Results are presented as deposition fluxes of NO3−, SO42−, PO43−, Cl−, F−, NH4+, Ca2+, Mg2+, Na+, K+, Zn2+, Fe3+, Mn2+, Pb2+ and H+, and compared with other locations in California and elsewhere. Deposition fluxes of anions and cations to the pine branches were low, several times lower than the values determined near the Emerald Lake Watershed (ELW), another sub-alpine location in the western Sierra Nevada. The sums of deposition fluxes of the measured cations and anions to pine surfaces were similar, in contrast to the ELW location where the sums of cation fluxes were much higher than the sums of anion fluxes. A strong positive correlation between depositions of NO3− and NH4+, as well as SO42− and Ca2+, suggested that large portions of these ions might have originated from particulate NH4NO3 and CaSO4 deposited on pine surfaces. An estimated total N dry deposition (surface deposition of NO3− and NH4+ and internal uptake of NO2 and HNO3) to the forested area of the EBLW was 29.54 eq ha−1 yr− (about 414 g H ha−1 yr−1).

Young 'Valencia' orange trees (Citrus sinensis(L) Osbeck) were grown for four years in large open-top chambers with ambient (nonfiltered) air or in outside air to determine any effects of the chambers on the air pollutant susceptibility of the trees. Long-term ozone average concentrations (12 hours, growing season) were 8% lower, and cumulative ozone dose (hourly values >0.1 microL/L) was 29% lower in ambient chambers compared to outside air. Fruit yields were much higher (>39%) for ambient chamber trees than for outside trees over three harvests, due at least partly to less fruit drop during the growing season for ambient chamber trees. Ambient chamber trees were much larger than outside trees and produced over twice as much leaf material over four years of study. Leaves on ambient chamber trees were larger and less dense than on outside trees. Leaves on ambient chamber trees were under more stress than leaves on outside trees during summer months; with lower stomatal conductances (14% average) and transpiration rates (12%), and more negative leaf water pressure potentials (28%). In contrast, leaves on ambient chamber trees had higher net photosynthetic rates (13%) and higher leaf starch concentrations prior to tree flowering (31%), than leaves on outside trees. more » While these results indicated large long-term impacts on tree growth which must be considered when using open-top chambers, they did not indicate any net effect of chambers on the air pollutant susceptibility of trees which would limit the usefulness of chamber tree data for air quality impact assessment purposes. « less

We have assessed, in 200 patients, the determinants of the reversal time of competitive neuromuscular block by anticholinesterase when alcuronium and atracurium neuromuscular block were antagonized by neostigmine 0.04 and 0.08 mg kg-1 and edrophonium 0.5 and 1.0 mg kg-1. A biexponential relationship was found between the reversal time (time from injection of anticholinesterase to a train-of-four ratio of 70%) and the degree of neuromuscular block at reversal (all groups; F ratio, P less than 0.05). Reversal time was determined by two processes: direct antagonism by the anticholinesterase and spontaneous recovery of the neuromuscular blocking agent, with the latter becoming the major determinant at profound levels of neuromuscular block (0-10% of control twitch height). Neostigmine, in the doses studied, appeared to have a higher "ceiling" of neuromuscular block which it completely antagonized, although edrophonium had a more rapid onset of action. The reversal time for alcuronium became progressively longer relative to atracurium as neuromuscular block increased because of the slower spontaneous recovery rate. Avoidance of profound neuromuscular block at the completion of surgery is required to ensure reliable antagonism of the block within 5-10 min by an anticholinesterase. Neostigmine 0.08 mg kg-1 was found to be the most effective agent in antagonizing profound neuromuscular block.

Atmospheric dry deposition of ions to branches of native Pinus contorta and Pinus monticola (natural surfaces), and nylon filters and Whatman paper filters (surrogate surfaces) were measured in the summer of 1987 in the vicinity of Emerald Lake Watershed (ELW) of the Sequoia National Park located on the western slope of the Sierra Nevada in California. Deposition fluxes of airborne NO−3, NH+4 and SO2−4 to native pines at the ELW were much higher than in the eastern Sierra Nevada, but several times lower than deposition fluxes to natural and surrogate surfaces at the highly polluted site in the San Gabriel Mountains of southern California. Deposition fluxes of NO3− and NH4+ to the natural and surrogate surfaces at the ELW were much higher than deposition of SO42−, providing the importance of N compounds in atmospheric dry deposition in this part of the western U.S. A deficit of inorganic anions in materials deposited to various surfaces indicated a possibility of substantial participation of organic acids in atmospheric dry deposition processes. Nylon and paper filters proved to be poor surrogate surfaces for the estimation of ionic dry deposition to conifer branches.

Ozone is a widespread component of polluted air. It is the cause of many adverse effects on the lung such as decreased athletic performance and exacerbation of asthma. Ozone inactivated acetylcholine esterase (AChE) both in intact washed human erythrocytes and in ghosts prepared from the erythrocytes. This is consistent (a) with the location of AChE on the outer face of the membrane and (b) with the change in structure of AChE when amino acids were oxidized. The glyceraldehyde-3-phosphate dehydrogenase (G3PDH) of intact washed erythrocytes was unaffected by ozone. However, ozone severely inactivated G3PDH of ghosts, much more severely than AChE in ghosts. This result raised questions about the relative permeability of intact erythrocytes and ghosts and also about the inherent susceptibility of the two enzymes. Inhibition of the ozone-treated erythrocyte AChE with the competitive inhibitor trimethyl-(p-aminophenyl) ammonium chloride was measured. The inhibited enzyme had a higher K(M) and slightly lower Vmax than the control. Ozone did not affect the K(M) of the uninhibited enzyme but decreased the K(M) of the inhibited enzyme. Ozone decreased the Vmax of both the inhibited and the uninhibited enzyme. The K(I) was unchanged by the treatment with ozone. This suggested that the active site of the enzyme was not affected by ozone, but other features of the protein were changed by ozone. The effects of products of lipid ozonolysis [hydrogen peroxide, nonanal, and 1-palmitoyl-2-(9-oxononanyl)-sn-3-glycerophosphorylcholine (PN1PC)] were tested on the ghost preparations. The ozonolysis products were tested at concentrations equivalent to calculated amounts that could have been produced by ozone. Hydrogen peroxide had no effect on the G3PDH and AChE. Nonanal slightly increased the permeability of the ghost membrane, as judged by the increase in rate of G3PDH in the absence of Triton X-100, but did not inhibit enzyme activity. PN1PC increased the permeability of the ghosts, as judged by the increase in rate of G3PDH in the absence of Triton X-100. There was also an increase in the activity of G3PDH in the presence of Triton X-100. AChE was not inhibited by ozone in the presence or absence of Triton X-100.

Concentrations of gaseous and particulate air pollutants, and deposition fluxes of NO 3 − , SO 4 2− , and NH 4 + ions to branches of California lilac (Ceanothus crassifolius Torr.), Coulter pine (Pine coulteri D. Don.), ponderosa pine (P. ponderosa Dougl. ex P. & C. Lawson), nylon filters, and paper filters were measured in open-top field chambers with different filtration materials and in chamberless outside plots

Desert winter annual plants: Camissonia claviformis, C. hirtella, Caulanthus cooperi, Chaneactis carphoclinia, C. stevioides, Cryptantha angustifolia, C. pterocarya, Erodium cicutarium, Festuca octoflora, Lupinus concinnus, Oenothera californica, Plantago insularis, Platystemon californica, Salvia columbariae, Thelypodium lasiophyllum, and Thysanocarpus curvipes growing on irrigated and non-irrigated plots were exposed in situ to elevated levels of ozone dispensed from an open air exposure system. Plants were exposed intermittently to a gradient of ozone of concentrations ranging between 44 and 133 ppb (nL L−1) for 35 h over a total of 216 h. Only three species were injured by ozone at the highest ozone concentrations. Leaf injury to C. claviformis—2 percent total foliar injury (TFI), C. hirtella—1 percent TFI, and Erodium cicutarium—2 percent TFI, developed at the highest ozone concentrations. Leaf injury to these species was similar on the irrigated and nonirrigated plots. Leaf water potential and stoma...

Forty-seven species of annual plants from the Mojave Desert were grown in pots and exposed in open-top field chambers located at Riverside, California to test their relative sensitivity to SO/sub 2/ and O/sub 3/. Exposures were 8 h/day for four or five days at 0, 0.05, 0.1, 0.2, 0.3 and 0.4 ppm O/sub 3/ or 0, 0.2, 0.5, 0.6, 0.8, 1.0 and 1.5 ppm SO/sub 2/. Species differed widely in their response to the pollutants. Three species, Camissonia claviformis, Camissonia hirtella and Cryptantha nevadensis, were quite sensitive to both pollutants, exhibiting leaf injury when exposed to 0.1 ppm O/sub 3/ or 0.2 ppm SO/sub 2/. Two species: Festuca octoflora and Lepidium lasiocarpum were tolerant to both pollutants, exhibiting no leaf injury with concentrations of 0.3 ppm O/sub 3/ or 1.5 ppm SO/sub 2/. The other species were intermediate in sensitivity, with O/sub 3/ sensitivity not always corresponding to SO/sub 2/ sensitivity. Total sulfur concentration analysis indicated that for 8 of 11 species tested, plants exposed to 0.2 ppm SO/sub 2/ had a higher sulfur concentration than nonexposed plants. Baileya pleniradiata and Perityle emoryi had the greatest increases in sulfur concentration for exposed versus control plants. To test for effects ofmore » the environmental and exposure system on plant sensitivity, 29 of the species exposed in the open-top chambers were grown in the ground and exposed with a modified chamberless zonal air pollution (ZAP) system to SO/sub 2/ in the Mojave Desert area near Daggett, California. Exposures were for a total of 37 h over six days to 0, 0.4, 0.8 and 1.0 ppm SO/sub 2/ with exposures only during periods with due west winds. Most of the species were not injured with any of the SO/sub 2/ exposure concentrations used with the ZAP system; only Camissonia claviformis showed injury at 0.8 ppm SO/sub 2/ and Oenothera californica exhibited injury at 1.0 ppm SO/sub 2/.« less

The response of shrubs of Larrea tridentata (DEC) Coville (creosotebush) exposed to sulphur dioxide (SO(2)) was evaluated using in situ plants of the Majove Desert. Larrea was exposed to acute levels of 0.3 to 2.0 microl litre(-1) SO(2) for periods up to 13 days using field chambers or an open-air fumigation system. Plants exposed in the spring exhibited considerable leaf injury (necrosis and defoliation) when exposed to 2.0 microl litre(-1) SO(2), and in the autumn had leaf injury when exposed to0.4microl litre(-1) SO(2). Injured plants had higher transpiration rates, less negative water pressure potentials, and/or lower photosynthetic rates than control plants. It is likely that Larrea would not be injured by the typically low SO(2) concentrations and dry environmental conditions of the Mojave Desert. However, if injury were to occur, it would be accompanied by changes in plant-water relations and photosynthesis, followed by recovery after the SO(2) stress was removed.

Tubulin has been purified from carrot suspension cells by ion-exchange chromatography and assembled into microtubules in the presence of 20 microM taxol. One-dimensional SDS-PAGE suggested that the alpha band migrated faster than the beta band (as has been established for some lower eukaryotic tubulins) and this heterology with brain tubulins was confirmed by peptide mapping. When subjected to two-dimensional gel electrophoresis, the plant tubulins could be separated into multiple alpha and beta isotypes. Immunoblotting, using monoclonal anti-tubulins, confirmed that the tubulin isotypes identified in taxol microtubules represent all of the tubulins present in homogenates of unsynchronised log-phase carrot suspension cells. All identified tubulins are therefore assembly-competent under these conditions. Plant cells can contain four different microtubule arrays, but cells arrested in G0/G1 contain only cortical microtubule arrays; such cells, however, exhibit the same tubulin profile as non-synchronised cells, thereby showing no restriction in the number of subunits during this phase of the cell cycle.