Invasive Snails Protect Their Young With Odd Poison
by Erik Stokstad 胡德良 译
Many kinds of snails are invading ecosystems all over the world, but the apple snail (Pomacea canaliculata) has a unique advantage: Almost no predators will eat its eggs. That's because the bright pink objects (pictured) are filled with a neurotoxin that scares off every predator except for red fire ants. Now, researchers have discovered that the neurotoxin, called PcPV2, is unusual for animals. First, it's a so-called AB toxin, which is used by plants and bacteria. And second, the apple snail creates it in an unprecedented way, combining a pair of molecules that resemble those belonging to the immune system of other animals. As for the embryonic snails, cocooned in a toxic egg, they are equipped with enzymes that can degrade the neurotoxin and use it for nutrition during development, researchers reported last week in PLOS ONE. No one knows how the ants survive. | 在全世界,有许多种类的蜗牛正在侵入生态系统,然而苹果螺(Pomacea canaliculata)有着奇特的优势:几乎没所有掠食者都不会吃它的卵。这是因为,其浅粉色的卵中充满了一种神经毒素,这种毒素会吓跑除红火蚁之外的所有掠食者。现在,研究人员发现这种毒素叫做PcPV2,对于动物来说是非同寻常的。首先,它是一种所谓的AB毒素,通常为植物和细菌所利用。其次,苹果螺以史无前例的方式生成这种毒素,将类似于其他动物免疫系统中的一对分子结合起来。上周,研究人员在《公共科学图书馆·综合》中报道说:对于裹在一枚毒卵中的胚胎蜗牛来说,它们拥有一种降解这种神经毒素的酶,而且在发育阶段可以将神经毒素作为营养成分加以吸收。没有人知道红火蚁食用苹果螺卵后是如何幸存下来的。 |
译自:美国《科学》杂志网站(3 June 2013, 3:40 PM)
原著:Erik Stokstad
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