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This pollen makes allergic persons cry. Each grain is impregnated with a chemical protective shield. This is bad news for nasal mucosa.
In an evolutionary sense, conifers belong to the oldest life forms on earth. For 250 million years, they had to withstand climate change, meteorite impacts and predators such as dinosaurs, beetle larvae and fungi. A product of this struggle for survival is displayed here. These are the pollen grains of Japanese cedar (Cryptomeria japonica).
Each of them is some kind of airborne bunker. Well protected in its interior, it houses the blueprint for a new tree. The wall of the bunker consists of several acid-and-heat-resistant layers. This way, the cedar ensures that the precious cargo is not damaged during flight to the female flower.
Protected by a Chemical Shield
But on the long journey, canny enemies lurk such as fungi. They could crack and digest the bunker with its content. Therefore, the cedars have also installed a chemical shield. It consists of defense proteins that are incorporated into the wall of the pollen grain. They spoil the appetite of the fungi by blocking their digestive enzymes Thus, the attackers are paralyzed and miss out on their expected meal. For the propagation success of the cedar this is very good.
People on the other hand are suffering from the sophisticated defense strategy. The defense proteins can cause severe allergic reactions once the pollen grains land on the nasal mucosa. Although the chemicals are harmless to most of us, the immune system of allergic persons thinks it has to defend itself and sets an army of antibodies in movement. This becomes noticeable as itching in the nose, a condition known as hay fever.
The problem is, that there are a lot of Japanese cedar in Japan. They were planted in large monocultures at the behest of the government after the Second World War for the reconstruction of the country. Today, the species coveres 12 percent of the country’s area. When the cedar flower, so much of the orange coloured pollen is released into the air that the forests look as if they were on fire.
Thus, every spring about ten percent of the population of Japan suffers from hay fever. Researchers investigate the allergens in order to develop an antidote.
Currently, the focus is on the surface of the cedar pollen. It is covered with so-called Ubisch-Bodies. They are small beads that can detach from the pollen grain. Researchers suspect that they contain powerful allergens, which could be the explanation for the strong reaction of the immune system.
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