最近，科学家在同步辐射X射线成像技术的帮助下“看到”活的射炮步甲（Bombardier Beetles，Brachinini）的攻击性的分泌物过程。射炮步甲的两个腺体，分别分泌对苯二酚和过氧化氢。当遇到危险时，腹部肌肉立即收缩，并打开一个名为内腔阀的结构，使两种物质在一个含酶的小室里混合——这将发生剧烈的化学反应，生成褐色刺激性的1,4-苯醌和水，并释放大量的热，瞬间可达100摄氏度以上，水立刻沸腾，压力突然增大，可将刺激性物质由射炮步甲的腹部后方喷射出来，射向敌人。同时，当发生反应时，一种称为弹性膜的柔性结构不断膨胀，关闭了内腔阀，阻止化合物的流动。当喷射出化合物时，腔内压力下降，而阀门又将再次打开，完成新一轮的过氧化氢与对苯二酚的化学反应。
Bombardier beetles (Brachinini) use a rapid series of discrete explosions inside their
pygidial gland reaction chambers to produce a hot, pulsed, quinone-based defensive spray.
The mechanism of brachinines’ spray pulsation was explored using anatomical studies and
direct observation of explosions inside living beetles using synchrotron x-ray imaging.
Quantification of the dynamics of vapor inside the reaction chamber indicates that spray
pulsation is controlled by specialized, contiguous cuticular structures located at the
junction between the reservoir (reactant) and reaction chambers. Kinematics models
suggest passive mediation of spray pulsation by mechanical feedback from the explosion,
causing displacement of these structures.
DOI: 10.1126/science.1261166
Science 1 May 2015: Vol. 348 no. 6234 pp. 563-567
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