Sensitization characteristics in allergic rhinitis and transport pathway for Artemisia pollen in northern Beijing, China.

The genus Artemisia, an important allergen related to Allergic Rhinitis (AR), is widespread in temperate regions. However, the sensitization rate of Artemisia pollen varies significantly, and the source of Artemisia pollen is not clear. Based on continuous daily airborne pollen monitoring in the summer and autumn of 2019 and 2020 in northern Beijing, the daily number of AR patient visits during the same period, and the detection of allergen serum-specific immunoglobulin E (sIgE) in some AR patients, this study discusses the sensitization rate of Artemisia pollen and its transmission pathway and possible source area. The results show that (1) Artemisia pollen is the most important airborne pollen in summer and autumn in northern Beijing, and the pollen concentration is significantly related to the daily number of AR patient visits; (2) the rate of AR patients testing positive for Artemisia pollen allergens is 32.35 %, which is the first risk allergen and is consistent with the high sensitization rate of Artemisia pollen in northern China; and (3) in addition to local sources, central and southern Inner Mongolia, southern Mongolia and northwestern China are potential source areas of Artemisia pollen within the study area. This study provides first-hand data for accurately understanding the allergenic characteristics and sources of Artemisia pollen in northern Beijing and provides a scientific basis for the prevention of AR induced by Artemisia pollen in patients in China.

Elevation-induced climate change as a dominant factor causing the late Miocene C(4) plant expansion in the Himalayan foreland.

During the late Miocene, a dramatic global expansion of C4 plant distribution occurred with broad spatial and temporal variations. Although the event is well documented, whether subsequent expansions were caused by a decreased atmospheric CO2 concentration or climate change is a contentious issue. In this study, we used an improved inverse vegetation modeling approach that accounts for the physiological responses of C3 and C4 plants to quantitatively reconstruct the paleoclimate in the Siwalik of Nepal based on pollen and carbon isotope data. We also studied the sensitivity of the C3 and C4 plants to changes in the climate and the atmospheric CO2 concentration. We suggest that the expansion of the C4 plant distribution during the late Miocene may have been primarily triggered by regional aridification and temperature increases. The expansion was unlikely caused by reduced CO2 levels alone. Our findings suggest that this abrupt ecological shift mainly resulted from climate changes related to the decreased elevation of the Himalayan foreland.