ABA is a major phytohormone that regulates a broad range of plant traits and is especially important for adaptation to environmental conditions. Our understanding of the molecular basis of ABA ...responses in plants improved dramatically in 2009 and 2010, banner years for ABA research. There are three major components; PYR/PYL/ RCAR (an ABA receptor), type 2C protein phosphatase (PP2C; a negative regulator) and SNF1-related protein kinase 2 (SnRK2; a positive regulator), and they offer a double negative regulatory system, PYR/PYL/RCAR--| PP2C--| SnRK2. In the absence of ABA, PP2C inactivates SnRK2 by direct dephosphorylation. In response to environmental or developmental cues, ABA promotes the interaction of PYR/PYL/RCAR and PP2C, resulting in PP2C inhibition and SnRK2 activation. This signaling complex can work in both the nucleus and cytosol, as it has been shown that SnRK2 phosphorylates basic-domain leucine zipper (bZIP) transcription factors or membrane proteins. Several structural analyses of PYR/PYL/RCAR have provided the mechanistic basis for this 'core signaling' model, by elucidating the mechanism of ABA binding of receptors, or the 'gate-latch-lock' mechanism of interaction with PP2C in inhibiting activity. On the other hand, intercellular ABA transport had remained a major issue, as had intracellular ABA signaling. Recently, two plasma membrane-type ABC transporters were identified and shed light on the influx/efflux system of ABA, resolving how ABA is transported from cell to cell in plants. Our knowledge of ABA responses in plants has been greatly expanded from intracellular signaling to intercellular transport of ABA.
The termination of the superintense 1997/1998 El Niño was extraordinarily abrupt. The May 1998 Madden‐Julian Oscillation (MJO), a massive complex of stormy tropical clouds, is among possible ...contributors to the abrupt termination. Despite having been sensationally proposed 18 years ago, the role of the MJO remained controversial and speculative because of the difficulty of sufficiently simulating the El Niño and MJO simultaneously. An ensemble simulation series using a newly developed, fully ocean‐coupled version of a global cloud system resolving numerical model replicated the specific atmosphere and ocean conditions of May 1998 in unprecedented detail, extending the prediction skill of the MJO to 46 days. Simulation ensemble members with stronger MJO activities over the Maritime Continent experienced quicker sea surface temperature drop in the eastern Pacific, confirming that the easterly winds associated with the remote MJO accelerated ocean upwelling to abruptly terminate the El Niño.
Key Points
We developed a new, fully ocean coupled global cloud system resolving numerical model
The model replicated the atmosphere and ocean conditions of May 1998 El Niño abrupt termination in unprecedented detail
Intensity of the Madden‐Julian oscillation over the Maritime Continent was related with the sea surface cooling in the eastern Pacific
Plain Language Summary
The ocean and atmosphere conditions of a extraordinarily abrupt termination of one of the most intense El Niño event ever recorded are replicated in unprecedented detail by using our newly developed global high‐resolution atmosphere‐ocean numerical model on one of the top‐tier super‐computers. Results show that a huge envelope of stormy activity centered over the Indonesian archipelago remotely enhanced easterly winds over the eastern Pacific ocean, which drove upward motion of cold water to the surface to suddenly end the El Niño condition. The newly developed model may improve predictions of weather tendencies and tropical cyclone probabilities at the sub‐seasonal to seasonal time‐range.
In this study, we show that black carbon (BC) mass concentrations measured by different techniques are consistent and traceable. First, we present the volatilities of 13 organic compounds passed ...through a heated inlet. These data were used to quantify the interference of organic aerosols on the BC measurement techniques. The masses of the refractory particles that incandesce (m*
ref
) were used to calibrate BC mass measured by a single-particle soot photometer (SP2), which uses laser-induced incandescence. This calibration was influenced little by refractory organics and agreed well with that of fullerene soot, which indicates the consistency of the standards. We estimated the interference of pyrolyzed refractory organics on the BC measured with a filter-based absorption photometer continuous soot monitoring system (COSMOS) with a heated inlet to be small in Asia. This was also confirmed by the stable mass absorption cross section (MAC) obtained by the high correlations between BC mass concentrations measured by COSMOS (M
COSMOS
) and those measured by the thermal-optical transmittance method (M
TOT
) (
Kondo et al. 2009
). M
COSMOS
was also compared with total BC mass concentrations measured with an SP2 (M
SP2
) in Tokyo in 2009. M
COSMOS
and M
SP2
were highly correlated (r
2
= 0.97) and agreed to within about 10% on average. These results demonstrate that M
SP2
, M
COSMOS
, and M
TOT
were nearly identical. Use of the masses of incandescing refractory BC particles for calibration of BC mass concentrations determined by different techniques gave consistent results.
The sources of elemental (EC) and organic carbon (OC) aerosols in Asian outflow were investigated in the spring of 2015 in terms of radiocarbon (14C) and molecular marker analyses. The contribution ...of fossil fuel (FF) sources to carbonaceous aerosols (TC) significantly increased in polluted air masses with enhancements in the concentrations of carbon monoxide. For EC, FF sources dominated in the polluted air masses. For OC, the contributions of non-FF sources other than biomass burning (BB) were found to be significant (comparable to or higher than those of FF sources), especially in air masses with higher values of the water-soluble fraction of OC (fWSOC) and 14C concentrations (F14C). Positive correlations between fWSOC and F14C indicate that the origins of TC (mainly OC) have great impacts on the water solubility variability and the subsequent cloud formation processes of OC during transport. We found the importance of natural sources as possible origins of OC in non-polluted (i.e., background) air. This study raises the need to further investigate the source apportionment of OC, especially its natural origins, for more accurately assessing the climatic impacts of EC and OC in East Asia.
Display omitted
•Source apportionment of carbonaceous aerosols in Asian outflow in the spring of 2015 was investigated in a Japanese remote island.•Biomass burning was not dominant emission process of carbonaceous aerosols at the observation site through the observation period.•Black carbon aerosols were mostly emitted from fossil fuel (FF) sources. (~90%).•4Organic carbon (OC) aerosols were significantly affected by non-FF sources as well as FF sources.•Major portion of non-FF-derived OC was likely originated from natural sources such as ocean and land vegetation.•Mixing between polluted and background air masses in Asian outflow regulated the water-soluble fraction of OC as well as source apportionment.
Submicron organic aerosol was measured simultaneously with an Aerodyne aerosol mass spectrometer (AMS) and a particle‐into‐liquid sampler (PILS) capable of measuring water‐soluble organic carbon ...(WSOC) during the winter and summer of 2004 in Tokyo. Both techniques are being used to investigate the formation of secondary organic aerosol (SOA), and the combined data sets provide unique insights. In summer, about 80% (40–65%) of organic aerosols were oxygenated when scaled by total (carbon) mass concentration, due to high photochemical activity, leading to the active formation of SOA. In winter the fraction of oxygenated organic aerosol is reduced to 39% (total mass base) and 23% (carbon mass base). Previous AMS studies have shown that signals at m/z 44 of the AMS mass spectra of ambient aerosols are dominated by COO+, which typically originates from oxygenated organic aerosols (OOA). The signals at m/z 44 and the derived OOA mass concentrations were highly correlated with WSOC (r2 = 0.78–0.91) throughout these seasons, indicating that OOA and WSOC were very similar in their chemical characteristics. Approximately 88 ± 29% of OOA was found to be water soluble on the basis of the comparison of the WSOC concentrations with those of oxygenated organic carbon (OOC) derived from the AMS data.
Recurring transboundary haze from Indonesian wildfires in previous
decades significantly elevated particulate matter (PM) concentrations in
Southeast Asia. During that event on 10 to 31 October 2015, ...we conducted a
real-time observation of non-refractory submicron PM (NR-PM1) in
Singapore using an Aerodyne aerosol mass spectrometer. Simultaneously, we
characterized carbonaceous components and organic aerosol (OA) tracers from
fine PM (PM2.5) samples to support source apportionment of the online
measurements. The real-time analysis demonstrated that OA accounted for
approximately 80 % of NR-PM1 mass during the wildfire haze period.
Source apportionment analysis applied to the OA mass spectra using the
multilinear-engine (ME-2) approach resulted in four factors: hydrocarbon-like
OA (HOA), biomass burning OA (BBOA), peat burning OA (PBOA), and oxygenated
OA (OOA). The OOA can be considered as a surrogate of both secondary organic
aerosol (SOA) and oxidized primary organic aerosol (OPOA), while the other
factors are considered as surrogates of primary organic aerosol (POA). The
OOA accounted for approximately 50 % of the total OA mass in NR-PM1,
while POA subtypes from wildfires (BBOA and PBOA) contributed to
approximately 30 % of the total OA mass. Our findings highlight the
importance of atmospheric chemical processes, which likely include POA
oxidation and SOA formation from oxidation of gaseous precursors, to the OOA
concentration. As this research could not separately quantify the POA
oxidation and SOA formation processes, further studies should attempt to
investigate the contribution of gaseous precursor oxidation and POA aging to
the OOA formation in wildfire plumes.
We report the evolution of the mixing state of black carbon (BC) particles in urban plumes measured by an airborne single particle soot photometer. The aircraft observations were conducted over the ...ocean near the coast of Japan in March 2004. The number fraction of coated BC particles with a core diameter of 180 nm increased from 0.35 to 0.63 within 12 hours (h), namely 2.3% h−1, after being emitted from the Nagoya urban area in Japan. BC particles with a core diameter of 250 nm increased at the slower rate of 1.0% h−1. The increase in coated BC particles was associated with increases in non‐sea salt sulfate and water‐soluble organic carbon by a factor of approximately two, indicating that these compounds contributed to the coating on the BC particles. These results give direct evidence that BC particles become internally mixed on a time scale of 12 h in urban plumes.
Mass concentrations of soot (typically comprising black and elemental carbon; BC and EC, respectively) aerosols, were measured at Yokosuka city, an industrial region in Japan in the early summer of ...2014. The results of laser–induced incandescence (LII) and evolved gas analysis (EGA) techniques were compared using a single particle soot photometer (SP2) and semi-continuous elemental/organic carbon analyzer (EC/OC analyzer), respectively. We revisited the procedure of SP2 calibration with a focus on investigating the relationship between LII intensity (SLII) and refractory BC (rBC) mass per particle (mPP) for some BC-proxies in the laboratory, as well as for ambient rBC particles in order to discuss the uncertainty of the SP2. It was found that the mPP–SLII for the fullerene soot and carbon black particles agreed well within 3% and 10%, respectively, with that for ambient rBC particles. This is the first time to suggest the use of carbon black as a reference material. We also found that the mPP–SLII for the aqueous deflocculated Acheson graphite particles with the correction factor given by Baumgardner et al. (2012) was still biased by around +20% to that for ambient rBC particles. EC quantified by the semi-continuous EC/OC analyzer using a thermal-protocol similar to that of Interagency Monitoring of Protected Visual Environments (IMPROVE–like), systematically showed higher concentrations than rBC measured by the SP2. The uncertainties related to SP2 cannot fully account for this difference. This result was likely caused by the contribution of charred organic materials to EC, which can be affected significantly by thermal-protocols for the EGA. The consistency and differences between rBC and EC are discussed with regard to comparing their respective mass concentrations.
•An SP2 was compared with a semi-continuous EC/OC analyzer.•The uncertainties with regard to SP2 calibration were revisited.•Carbon black is another candidate as an SP2 calibration standard.•rBC mass was consistent with EC mass within the uncertainties related to EGA.•Differences in thermal-protocols are very important to compare rBC with EC.
We present results from the observation of fluorescent (FL) aerosols in Tokyo in the spring of 2013. Ambient aerosol particles were analyzed using a single‐particle laser‐induced fluorescence ...instrument. The fluorescent emission from a single particle excited by a pulsed UV laser (excitation wavelength of 263 nm) was detected by three photomultiplier tubes with band‐pass filters (fluorescence wavelength of 335–379, 420–500, and 500–600 nm). Fluorescence patterns from single particles were analyzed for investigating fluorophores and their sources using backward trajectory analysis, factor analysis, and a comparison with other tracer observations. The backward trajectory analysis suggested possible influences of long‐range transport from northern China in some cases. Observed supermicron FL aerosols were classified into two types: combustion‐ and dust‐type particles. The detection of combustion‐type FL aerosols, which showed temporal variations similar to nitrogen oxides and elemental carbon, implied the presence of polyaromatic hydrocarbons (PAHs) and their derivatives. Dust‐type FL aerosols, which were well correlated with the lidar‐derived dust‐aerosol optical depth near the surface (<1 km) and with mineral ions, were dominant in the supermicron size range. The number concentrations of coarse FL aerosols (≥2 µm), with which nonnegligible levels of fluorescence were recorded in all three channels, increased during Asian dust events (relative to a local dust event). It is suggested that PAHs and/or biological materials mixed with dust particles were transported from the North China Plain to the outflow region in East Asia during the observation period. Moreover, the autofluorescence measurement of airborne particles can be substantially affected by nonbiological materials in this region.
Key Points
Fluorescent (FL) aerosols were measured in Tokyo
FL aerosols in Tokyo were classified into combustion and dust types
Asian dust particles were important carriers of fluorophores
Inositol 1,4,5‐trisphosphate (IP3) plays a key role in Ca2+ signalling, which exhibits a variety of spatio‐temporal patterns that control important cell functions. Multiple subtypes of IP3 receptors ...(IP3R‐1, ‐2 and ‐3) are expressed in a tissue‐ and development‐specific manner and form heterotetrameric channels through which stored Ca2+ is released, but the physiological significance of the differential expression of IP3R subtypes is not known. We have studied the Ca2+‐signalling mechanism in genetically engineered B cells that express either a single or a combination of IP3R subtypes, and show that Ca2+‐signalling patterns depend on the IP3R subtypes, which differ significantly in their response to agonists, i.e. IP3, Ca2+ and ATP. IP3R‐2 is the most sensitive to IP3 and is required for the long lasting, regular Ca2+ oscillations that occur upon activation of B‐cell receptors. IP3R‐1 is highly sensitive to ATP and mediates less regular Ca2+ oscillations. IP3R‐3 is the least sensitive to IP3 and Ca2+, and tends to generate monophasic Ca2+ transients. Furthermore, we show for the first time functional interactions between coexpressed subtypes. Our results demonstrate that differential expression of IP3R subtypes helps to encode IP3‐mediated Ca2+ signalling.
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