Health effects of PM2.5 sources on children's allergic and respiratory symptoms in Fukuoka, Japan.

Exposure to fine particulate matter (PM2.5) is a potential aggravating factor for respiratory and allergic diseases. However, which PM2.5 sources are associated with such diseases remains unclear. This study aimed to investigate the association of PM2.5 sources with allergic and respiratory symptoms in schoolchildren. PM2.5 samples were collected in Fukuoka during the spring in 2014 and 2015. Asian dust was observed in 2014. Ion components, elemental components, and organic components were analyzed. Positive matrix factorization (PMF) was conducted to calculate PM2.5 concentrations from each source. Mixed logistic regression analysis with a random intercept for each schoolchild was performed to evaluate the association of components and sources with symptoms. Among 2317 schoolchildren, the mean prevalence was 28.9%, 23.6%, 11.2%, and 11.4% for lower respiratory, nasal, ocular, and skin symptoms, respectively. PMF identified the following six PM2.5 sources "Secondary sulfate and coal combustion", "Secondary nitrate", "Heavy oil combustion", "Sea salt", "Soil" and "Traffic emission". An interquartile range of PM2.5 mass was associated with nasal (Odds ratios 1.08, 95% confidence interval [1.03, 1.13]), ocular (1.10, [1.04, 1.16]), and skin symptoms (1.13, [1.06, 1.20]). Among the source factors, "Heavy oil combustion" was significantly associated with nasal symptom (1.11, [1.05, 1.18]) while "Sea salt" was associated with nasal (1.06, [1.02, 1.11]) and skin (1.073, [1.01, 1.14]) symptoms. We found "Soil", which might be affected by Asian dust, was associated with ocular (1.07, [1.03, 1.10]) and skin (1.05, [1.01, 1.08]) symptoms. Further studies in other seasons or places are needed to clarify the influence of PM2.5 sources on children's health.

Activation of a Rac GTPase by the NLR family disease resistance protein Pit plays a critical role in rice innate immunity.

The nucleotide-binding domain and leucine-rich repeat-containing (NLR) family proteins recognize pathogen-derived molecules and trigger immune responses in both plants and animals. In plants, the direct or indirect recognition of specific pathogen effectors by NLRs culminates in a hypersensitive response (HR) and the production of reactive oxygen species (ROS), key components of the plant defense response. However, the molecules activated by NLRs and how they induce immune responses are largely unknown. We found that the rice GTPase OsRac1 at the plasma membrane interacts directly with Pit, an NLR protein that confers resistance to the rice blast fungus. OsRac1 contributes to Pit-mediated ROS production as well as the HR and is required for Pit-mediated disease resistance in rice. Furthermore, the active form of Pit induces the activation of OsRac1 at the plasma membrane. Thus, OsRac1 is activated by Pit during pathogen attack and plays a critical role in Pit-mediated immunity in rice.

RACK1 functions in rice innate immunity by interacting with the Rac1 immune complex.

A small GTPase, Rac1, plays a key role in rice (Oryza sativa) innate immunity as part of a complex of regulatory proteins. Here, we used affinity column chromatography to identify rice RACK1 (for Receptor for Activated C-Kinase 1) as an interactor with Rac1. RACK1 functions in various mammalian signaling pathways and is involved in hormone signaling and development in plants. Rice contains two RACK1 genes, RACK1A and RACK1B, and the RACK1A protein interacts with the GTP form of Rac1. Rac1 positively regulates RACK1A at both the transcriptional and posttranscriptional levels. RACK1A transcription was also induced by a fungal elicitor and by abscisic acid, jasmonate, and auxin. Analysis of transgenic rice plants and cell cultures indicates that RACK1A plays a role in the production of reactive oxygen species (ROS) and in resistance against rice blast infection. Overexpression of RACK1A enhances ROS production in rice seedlings. RACK1A was shown to interact with the N terminus of NADPH oxidase, RAR1, and SGT1, key regulators of plant disease resistance. These results suggest that RACK1A functions in rice innate immunity by interacting with multiple proteins in the Rac1 immune complex.

RAR1 and HSP90 form a complex with Rac/Rop GTPase and function in innate-immune responses in rice.

A rice (Oryza sativa) Rac/Rop GTPase, Os Rac1, is involved in innate immunity, but its molecular function is largely unknown. RAR1 (for required for Mla12 resistance) and HSP90 (a heat shock protein 90 kD) are important components of R gene-mediated disease resistance, and their function is conserved in several plant species. HSP90 has also recently been shown to be important in mammalian innate immunity. However, their functions at the molecular level are not well understood. In this study, we examined the functional relationships between Os Rac1, RAR1, and HSP90. Os RAR1-RNA interference (RNAi) rice plants had impaired basal resistance to a compatible race of the blast fungus Magnaporthe grisea and the virulent bacterial blight pathogen Xanthomonas oryzae. Constitutively active Os Rac1 complemented the loss of resistance, suggesting that Os Rac1 and RAR1 are functionally linked. Coimmunoprecipitation experiments with rice cell culture extracts indicate that Rac1 forms a complex with RAR1, HSP90, and HSP70 in vivo. Studies with Os RAR1-RNAi and treatment with geldanamycin, an HSP90-specific inhibitor, showed that RAR1 and HSP90 are essential for the Rac1-mediated enhancement of pathogen-associated molecular pattern-triggered immune responses in rice cell cultures. Furthermore, the function of HSP90, but not RAR1, may be essential for their association with the Rac1 complex. Os Rac1 also regulates RAR1 expression at both the mRNA and protein levels. Together, our results indicate that Rac1, RAR1, HSP90, and HSP70 form one or more protein complexes in rice cells and suggest that these proteins play important roles in innate immunity in rice.

A sphingolipid elicitor-inducible mitogen-activated protein kinase is regulated by the small GTPase OsRac1 and heterotrimeric G-protein in rice 1[w].

Mitogen-activated protein kinase (MAPK) cascades are activated in plants during responses to pathogens or to pathogen-derived elicitors and mediate intracellular stress responses. Here, we show that a rice (Oryza sativa) MAPK, OsMAPK6, was posttranslationally activated in a cell culture by a sphingolipid elicitor. Suppression of OsMAPK6 expression by RNA interference resulted in a strong reduction of pathogen-induced Phe ammonia-lyase mRNA, whereas the mRNA level of another rice MAPK, OsMAPK5a, was highly increased. Silencing of a small GTPase, OsRac1, by RNA interference or loss-of-function mutation (d1) of the heterotrimeric G-protein alpha-subunit gene resulted in a strong reduction of the OsMAPK6 protein levels and of kinase activation by a sphingolipid elicitor. Furthermore, coimmunoprecipitation experiments with OsRac1 and OsMAPK6 proteins showed that OsMAPK6 is closely associated with the active form of OsRac1, but not with inactive forms of OsRac1. These results indicate that these two G-proteins regulate an elicitor-inducible MAPK in rice at the protein level.

Survey of volatile organic compounds found in indoor and outdoor air samples from Japan.

Indoor air quality is currently a growing concern, mainly due to the incidence of sick building syndrome and building related illness. To better understand indoor air quality in Japan, both indoor and outdoor air samples were collected from 50 residences in Iwate, Yamanashi, Shiga, Hyogo, Kochi and Fukuoka Prefectures. More than 100 volatile organic compounds (VOCs) were analyzed by thermal desorption-gas chromatography/mass spectrometry method. The most abundant class of compounds present in the indoor air samples were identified (i.e. alkanes, alkylbenzenes and terpenes). For 30% of the indoor air samples, the sum of each VOC exceeded the current provisional guideline value for total VOC (TVOC, 400 microg/m3). The major component of these samples included linear and branched-chain alkanes (possibly derived from fossil fuels), 1,4-dichlorobenzene (a moth repellent), alpha-pinene (emission from woody building materials) and limonene (probably derived from aroma products). As an unexpected result, one residence was polluted with an extremely high concentration of 1,1,1,2-tetrafluoroethane (720 microg/m3), suggesting accidental leakage from a household appliance such as a refrigerator. The results presented in this paper are important in establishing the Japanese target compound list for TVOC analysis, as well as defining the current status of indoor air quality in Japan.