早晨一杯咖啡讓全世界睡眼惺忪、昏昏沉沉的人變成警覺,、注意力集中的思想者,。許多研究證實(shí)了咖啡因可增強(qiáng)人的記憶的功效。據(jù)一項(xiàng)新的研究報告，咖啡因似乎還能極大地影響蜜蜂對花朵氣味的長期記憶,。除了各種糖之外,，許多植物的花蜜含有像咖啡因和煙堿這樣的化合物。這些物質(zhì)在高濃度時的苦味能阻嚇食草動物,。但在低濃度時,，授粉的蜜蜂似乎更喜歡含有咖啡因的花蜜。
在一項(xiàng)刊登在國際雜志Science上的研究報告中,，Geraldine Wright及其同事發(fā)現(xiàn),，咖啡屬和柑桔屬花品種的咖啡因含量恰好可以引誘這些嗡嗡作響的授粉昆蟲。在他們的試驗(yàn)中,，研究人員訓(xùn)練蜜蜂將某種花香與一種糖的獎勵進(jìn)行關(guān)聯(lián),。在僅僅給出該種氣味時,，感受到花香氣味的蜜蜂會伸出它們的管狀口器,，仿佛是在等待某種獎勵。當(dāng)這種糖的獎勵還含有咖啡因時,，有三倍之多的蜜蜂在24小時之后還能記住該種花香,，有兩倍之多的蜜蜂會在三天之后仍記得該種花香。
文章的作者在對蜜蜂的大腦做更仔細(xì)的觀察后發(fā)現(xiàn),，咖啡因觸發(fā)了涉及嗅覺學(xué)習(xí)和記憶的神經(jīng)元膜電位改變,。該研究提示，如果咖啡因能幫助蜜蜂更好地記住某種花的特性,，那么這些授粉昆蟲就更有可能保持對這些花的專一,，而且會漠視其它的花。需要做進(jìn)一步的研究以確認(rèn)在花蜜中的這些藥物是否還有成癮的作用,。一篇《觀點(diǎn)欄目》文章重點(diǎn)介紹了這些新的發(fā)現(xiàn),。（生物谷Bioon.com）
doi:10.1126/science.1228806
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Caffeine in Floral Nectar Enhances a Pollinator's Memory of Reward
G. A. Wright1,*, D. D. Baker2, M. J. Palmer3, D. Stabler1,2, J. A. Mustard4, E. F. Power1,2, A. M. Borland2, P. C. Stevenson5,6
Plant defense compounds occur in floral nectar, but their ecological role is not well understood. We provide evidence that plant compounds pharmacologically alter pollinator behavior by enhancing their memory of reward. Honeybees rewarded with caffeine, which occurs naturally in nectar of Coffea and Citrus species, were three times as likely to remember a learned floral scent as were honeybees rewarded with sucrose alone. Caffeine potentiated responses of mushroom body neurons involved in olfactory learning and memory by acting as an adenosine receptor antagonist. Caffeine concentrations in nectar did not exceed the bees' bitter taste threshold, implying that pollinators impose selection for nectar that is pharmacologically active but not repellent. By using a drug to enhance memories of reward, plants secure pollinator fidelity and improve reproductive success
