Biogenic volatile organic compounds (VOCs) are a significant source of global secondary organic aerosol (SOA); however, quantifying their aerosol forming potential remains a challenge. This study ...presents smog chamber laboratory work, focusing on SOA formation via oxidation of the emissions of two dominant tree species from boreal forest area, Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies), by hydroxyl radical (OH) and ozone (O3 ). Oxidation of α-pinene was also studied as a reference system. Tetramethylethylene (TME) and 2-butanol were added to control OH and O3 levels, thereby allowing SOA formation events to be categorized as resulting from either OH-dominated or O3 -initiated chemistry. SOA mass yields from α-pinene are consistent with previous studies while the yields from the real plant emissions are generally lower than that from α-pinene, varying from 1.9% at an aerosol mass loading of 0.69 μg m-3 to 17.7% at 26.0 μg m-3 . Mass yields from oxidation of real plant emissions are subject to the interactive effects of the molecular structures of plant emissions and their reaction chemistry with OH and O3 , which lead to variations in condensable product volatility. SOA formation can be reproduced with a two-product gas-phase partitioning absorption model in spite of differences in the source of oxidant species and product volatility in the real plant emission experiments. Condensable products from OH-dominated chemistry showed a higher volatility than those from O3 -initiated systems during aerosol growth stage. Particulate phase products became less volatile via aging process which continued after input gas-phase oxidants had been completely consumed.
We applied two tandem differential mobility analyzer methods to shed light on the evolution of the nucleation- and Aitken-mode-particle compositions at a virgin boreal-forest site during nucleation ...events in varying conditions. The overall results show a clear anthropogenic influence on the nucleation- and Aitken-mode-particle compositions during the events. The SO2/MTOP and NOx/MTOP (monoterpene oxidation products) ratios best explain the variation in the nucleation mode composition during clean and pollution-affected events, suggesting also the importance of organic sulfur compounds, in addition to other sulfur, nitrogen and organic compounds, in particle formation, composition and properties. During the cleanest events, MTOP explain well the time behaviour of the 10-nm particle composition with an estimated organic fraction of over 95%.
We measured the number concentrations and size distributions of aerosol particles and air ions with a differential mobility particle sizer and air ion spectrometer, respectively, during a roadside ...campaign conducted in Kuopio (Savilahti), Finland, between 16 June and 2 July 2004. The average cluster ion (0.3–1.8 nm) concentrations were quite low (around 320 cm–3 and 280 cm–3 for negative and positive ions) during the whole period. For comparison, cluster ion concentrations in a rural SMEAR II station in Hyytiälä, southern Finland, were at the same time almost three times higher. Negative intermediate ions (1.8–7.5 nm) reached maximum concentrations of 620 cm–3 in Kuopio, while the average concentrations were in the range 60–80 cm–3 depending slightly on the wind direction. Positive intermediate ion concentrations were lower. We observed higher amounts of the intermediate ions usually during rain but also during non-rain periods indicative of short-term secondary particle formation. Large ion (7.5–40 nm) concentrations (average values of 500–800 cm–3) were 2–3 times higher in Kuopio than at the SMEAR II station. Straightforward impact of traffic was observed when the wind blew from the road: an increase in the traffic density increased concentrations of large ions.
The Second Pallas Cloud Experiment (Second PaCE) was conducted at the Pallas-Sodankylä Global Atmosphere Watch (GAW) station in northern Finland from 16 September to 6 October 2005. Measured ...parameters included aerosol number size distribution, aerosol chemical composition, aerosol hygroscopic growth factor, cloud droplet number size distribution and meteorological parameters. Air mass back trajectories were also calculated. The particulate volume and the inorganic fraction (IO) of particulate mass depended strongly on the air-mass history: central European air masses contain much more particulate matter and have higher IO than marine air masses. The hygroscopic growth factor of particles was positively correlated with the IO. Aerosol activation into cloud droplets was studied for accumulation mode particles (dp > 100 nm). The activation of these particles did not show clear dependency on the number concentration of accumulation mode particles or on IO. These two parameters were positively correlated and their effects on the particle activation could not be separated.
Marine secondary organic compounds have a huge potential to effect on ultrafine particles properties and thus climatologically important issues. However, the role of organic compounds in recently ...formed nucleation event particles is widely undetermined. In this work, organic fraction in recently formed nucleation event particles has been experimentally studied in North Atlantic coast (Mace Head, Ireland) during MAP 2006 summer campaign. The results indicate the importance of organic compounds in the nucleation and the lower end of Aitken mode particles formation and define quantitative amount of secondary organic compounds in those newly formed clean marine air particles at the coastal site.
Keywords Particle formation, marine coast, biogenic secondary organics fraction
A measurement site for aerosol-cloud interaction studies is described. The newly established measurement site at Puijo observation tower produces data from semiurban environment for climatic models ...and particle formation studies. In addition to the basic measurements, intensive yearly measurement campaigns are organized at the station. The first aerosol-cloud interaction experiment (PUCE1) took place in October–November 2006. Some results of the measurement campaing are presented and discussed.
Keywords Aerosol-cloud interaction, aerosol mass spectrometry, urban aerosols
Cysteine-rich receptor-like kinases (CRKs) are transmembrane proteins characterized by the presence of two domains of unknown function 26 (DUF26) in their ectodomain. The CRKs form one of the largest ...groups of receptor-like protein kinases in plants, but their biological functions have so far remained largely uncharacterized. We conducted a large-scale phenotyping approach of a nearly complete crk T-DNA insertion line collection showing that CRKs control important aspects of plant development and stress adaptation in response to biotic and abiotic stimuli in a non-redundant fashion. In particular, the analysis of reactive oxygen species (ROS)-related stress responses, such as regulation of the stomatal aperture, suggests that CRKs participate in ROS/redox signalling and sensing. CRKs play general and fine-tuning roles in the regulation of stomatal closure induced by microbial and abiotic cues. Despite their great number and high similarity, large-scale phenotyping identified specific functions in diverse processes for many CRKs and indicated that CRK2 and CRK5 play predominant roles in growth regulation and stress adaptation, respectively. As a whole, the CRKs contribute to specificity in ROS signalling. Individual CRKs control distinct responses in an antagonistic fashion suggesting future potential for using CRKs in genetic approaches to improve plant performance and stress tolerance.
Plant PARPs, PARGs and PARP-like Proteins Vainonen, Julia P; Shapiguzov, Alexey; Vaattovaara, Aleksia ...
Current protein & peptide science,
11/2016, Letnik:
17, Številka:
7
Journal Article
Recenzirano
Poly(ADP-ribos)ylation, originally described as a mechanism of DNA break repair, is now considered as part of a complex regulatory system involved in dynamic reorganization of chromatin structure, ...transcriptional control of gene expression and regulation of metabolism. In plants poly(ADP-ribos)ylation has received surprisingly little attention. It has been implicated in abiotic and biotic stress responses, cell cycle control and development; however, the molecular mechanisms and proteins involved are largely unknown. In this review we summarize current knowledge on plant PARP, PARG and PARP-like domain containing proteins and discuss their possible roles in plant development, immune responses, programmed cell death and stress responses in general. The genome of the model plant Arabidopsis contains three genes encoding PARP proteins, two of which have been shown to be active PARPs, and two genes encoding PARG proteins, one of which was shown to possess enzymatic activity. In addition, SROs (Similar to RCD One) represent a plant specific family of proteins containing a PARP-like domain. Although bioinformatics and biochemical data suggest that the PARP-like domain in SRO proteins does not have PARP activity, these proteins play a significant role in stress response as revealed by mutant analyses. SRO proteins interact with transcription factors involved in various stress and developmental responses and are suggested to serve as hubs in many signaling pathways. Altogether current data imply that poly(ADP-ribos)ylation plays significant regulatory role in many aspects of plant biology.
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