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Some types of airborne pollen can cause pollinosis, and several studies have been conducted on the fluctuation and prediction of their dispersal amount. In Sapporo, Betula pollen is the main cause of hay fever, as in Europe and North America, and various types of pollen other than Betula pollen are dispersed from early spring to autumn. These pollen grains vary in size and shape, and the distribution of their sources is also diverse. In this study, in order to obtain knowledge about the localized pollen dispersion trends within the same city, airborne pollen was comprehensively observed for six years at two sites, one in the center of Sapporo and the other about 10 km away near the mountain area. In addition, stellate hairs, which are airborne substances derived from plants other than pollen, were also observed. Cryptomeria pollen showed the highest correlation between the two sites among all 17 pollen groups. Betula pollen includes three species ( B. platyphylla , B. maximowicziana and B. ermanii ) that differ in dispersal time, size and distribution of source plants, but it showed a high correlation between the two sites. Although it was revealed that the trends differed depending on the pollen, it is interesting that large pine pollen with air sacs showed high correlation only in the daily fluctuations. We believe that it is useful information that a statistically high correlation was shown between the two locations in both daily and annual fluctuations of Cryptomeria and Betula pollens, which are involved in pollinosis in Japan.

Free fatty acids (FFAs) are generated by the reaction of lipases with membrane lipids. Generated polyunsaturated fatty acids (PUFAs) containing more than two double bonds have toxic effects in photosynthetic organisms. In the present study, we examined the effect of exogenous FFAs in the growth medium on the activity of photosystem II (PSII) under strong light in the cyanobacterium Synechocystis sp. PCC 6803 (Synechocystis). PUFAs but not monounsaturated fatty acids accelerated the rate of photodamage to PSII by inactivating electron transfer at the oxygen-evolving complex. Moreover, supplemented PUFAs were specifically incorporated into the sn-2 position of phosphatidylglycerol (PG), which usually contains C16 fatty acids at the sn-2 position in Synechocystis cells. The disruption of the gene for an acyl-ACP synthetase reduced the effect of PUFAs on the photoinhibition of PSII. Thus, the specific incorporation of PUFAs into PG molecules requires acyl-ACP synthetase and leads to an unstable PSII, thereby accelerating photodamage to PSII. Our results are a breakthrough into elucidating the molecular mechanism of the toxicity of PUFAs to photosynthetic organisms.