Laboratory of Marine Biology, Earth and Life Institute, Université catholique de Louvain, 3 Place Croix du Sud, 1348 Louvain-la-Neuve, Belgium.
Biol Lett. 2010 Oct 23;6(5):685-7. doi: 10.1098/rsbl.2010.0167. Epub 2010 Apr 21.
Bioluminescence is a common feature in the permanent darkness of the deep-sea. In fishes, light is emitted by organs containing either photogenic cells (intrinsic photophores), which are under direct nervous control, or symbiotic luminous bacteria (symbiotic photophores), whose light is controlled by secondary means such as mechanical occlusion or physiological suppression. The intrinsic photophores of the lantern shark Etmopterus spinax were recently shown as an exception to this rule since they appear to be under hormonal control. Here, we show that hormones operate what amounts to a unique light switch, by acting on a chromatophore iris, which regulates light emission by pigment translocation. This result strongly suggests that this shark's luminescence control originates from the mechanism for physiological colour change found in shallow water sharks that also involves hormonally controlled chromatophores: the lantern shark would have turned the initial shallow water crypsis mechanism into a midwater luminous camouflage, more efficient in the deep-sea environment.
生物发光在深海的永久黑暗中很常见。在鱼类中，光由包含发光细胞（内在发光器官）的器官发出，这些细胞直接受神经控制，或者由共生发光细菌（共生发光器官）发出，其光受机械遮挡或生理抑制等次要手段控制。灯笼鲨鱼 Etmopterus spinax 的内在发光器官最近被证明是该规则的一个例外，因为它们似乎受到激素的控制。在这里，我们表明，激素通过作用于虹彩色素细胞来操纵相当于独特的灯光开关，从而调节色素转移产生的光发射。这一结果强烈表明，这种鲨鱼的发光控制源于在浅水中鲨鱼中发现的生理颜色变化机制，该机制也涉及受激素控制的色素细胞：灯笼鲨鱼将最初的浅水环境伪装机制转变为中上层水域的发光伪装，在深海环境中更有效。
