The pollen record from the Takashima-oki core in Lake Biwa provides information on orbital-scale vegetation variability during MIS 6, 5, 4, and 3. Pinaceous conifers, such as Picea and Tsuga, became dominant around Lake Biwa in MIS 6. In the first half of the last interglacial, deciduous broad-leaved forests composed mainly of deciduous oaks and beech developed, whereas the development of evergreen forests was limited by cold winter due to low winter insolation. In the second half of this period, under a moderate winter climate, due to increasing winter insolation, evergreen oaks increased. Lagerstroemia trees were present throughout the entirety of the last interglacial period. Temperate conifers, such as Cryptomeria japonica, Sciadopitys verticillata, and Cupressaceae trees, were dominant during MIS 5. Cryptomeria japonica then became dominant, especially during the second half of MIS 5e, MIS 5c, and MIS 5a. During MIS 4, pinaceous conifers, such as Pinus subgenus Haploxylon, Tsuga, and Picea, increased again. Mixed forests composed of deciduous broad-leaved trees, temperate conifers, and pinaceous conifers expanded during MIS 3.

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To assess the environmental effects of genetically modified (GM) crops and to gather data to support regulations to control the co-existence of GM and non-GM crops, we studied the percentage of maize hybrids over a range of several hundred meters. In a large experimental field, we recorded the number of airborne pollen grains, the percentage of hybrids, and various meteorological factors over 3 years. Here we focus on the spatial variation in long-range hybrid percentages and the effects of weather. (1) The total rainfall from the date of first anthesis of the donor plant until the day prior to the pollen emission peak affected the number of airborne pollen grains during the peak period of pollen emission. Rainfall also had a major effect on the variation in number of airborne pollen grains with passage of day. (2) The percentage of hybrids in the recipient field decreased exponentially with distance from the donor field, but did not reach zero even at 800m from the donor field. It continued to decrease slightly, and did not become a constant even at the furthest side of the recipient field. (3) Correlations between the percentage of hybrids and meteorological factors were greater at mid range (50-200m) than at long range (200-800m). (4) The higher the wind speed, the smaller the decreasing rate in hybrid percentages in the area of the recipient field with distance from the donor field. (5) The stronger the solar radiation, the larger the decreasing rate in hybrid percentages in the area of the recipient field with distance from the donor field. Further studies are planned to model pollen emission and hybridization processes.

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Patients with pollinosis caused by Japanese cedar (Cryptomeria japonica) pollen often have additional allergy to the pollen of Hinoki (Chamaecyparis obtusa). This phenomenon is due to cross-allergenicity between Cry j 1, the allergen from C. japonica pollen, and Cha o 1, the allergen of C. obtusa pollen. In this study we have surveyed pollen of various species for signs of cross-allergenicity with the allergens Cry j 1 and Cry j 2 from C. japonica. Mature pollen grains from a range of woody dicotyledonous species were examined by the enzyme linked immunosorbent assay (ELISA) using the anti-monoclonal antibody (anti-mAb) 013 against the allergen Cry j 1, and anti-mAb T27 against the allergen Cry j 2. Anti-mAb 013 reacted with Morus bombycis pollen twice as strongly as with C. obtusa pollen; it also reacted weakly with pollen from Sambucus sieboldiana, Betula platyphylla, Mallotus japonicus and Myrica rubra. However, Anti-mAb T27 only reacted with B. platyphylla pollen. Moreover, immunocytochemical localization of Cry j 1- and Cry j 2-like proteins was examined in the pollen of these species, and showed cross-reactivity in ELISA. Anti-mAb 013 showed marked reactivity with the orbicules, exine, cytosol, and starch granules in the pollen of C. obtusa and B. platyphylla but only weak reactivity with the pollen of the other species. Anti-mAb T27 only reacted with the pollen of B. platyphylla and C. obtusa. These results suggest that as well as C. obtusa pollen, B. platyphylla pollen may have cross-allergenicity with C. japonica pollen.

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A reconstruction of the vegetation during the last 50 years for the Lake Shumarinai watershed, northern Hokkaido, Japan was carried out using pollen data from a sediment core. The average sedimentation rate was estimated as ca. 3mm year^<-1> based on Pb-210 and Cs-137 dating. Compared with other lakes in Japan the sedimentation rate is 1.5 times higher than for Lake Biwa and Lake Kizaki, and one-fourth that of Lake Suwa. In the present study, pollen accumulation rates for the last 40 years ranged between 1.7×10^4 and 2.9×10^4 grains cm^<-2> year^<-1>. Pollen assemblages were dominated by deciduous trees such as Quercus subgenus Lepidobalanus, Betula and Alnus with conifers such as Abies and Picea occurring throughout the core. These data indicate that, over the last 50 years, the vegetation of the Lake Shumarinai watershed has been similar to the current mixed forest which consists of Quercus mongolica var. grosseserrata, Betula ermanii, Alnus japonica, Abies sachalinensis and Picea glehnii.

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Progress of the Cryptomeria japonica pollen front in 2010 (Fig 1) was monitored by tracking the first day of pollen release using a Durham sampler at 103 sites, and an IS-Rotary sampler at 13 sites, distributed from Kyushu to Hokkaido. Results from the Durham sampler showed that, by late January, the pollen front had reached Nagasaki, the western region of Kyushu, and the southern areas of Kanto. Shortly after, in early to mid February, the front was observed in wider areas from Kanto, Tokai, and the southern regions of the Kii Peninsula, Shikoku, western areas of Chugoku and the whole of Kyushu. In late February, the front had reached the northern regions of Kinki, Hokuriku, the northern regions of Chubu and the southern areas of Tohoku districts. By early to mid March the front had reached central Tohoku and, late in March, it had reached northern Tohoku. The front finally arrived in the western region of Hokkaido by early April.

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