Haygood M G, Distel D L
Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla 92093-0202.
Nature. 1993 May 13;363(6425):154-6. doi: 10.1038/363154a0.
Bioluminescent symbioses range from facultative associations to highly adapted, apparently obligate ones. The family Anomalopidae (flashlight fishes) encompasses five genera of tropical reef fishes that have large suborbital light organs. The suborder Ceratioidei (deep-sea anglerfishes) contains 11 families. In nine of these, females have a bioluminescent lure that contains bacterial symbionts. In all other fish light-organ symbioses (occurring in 10 families in 5 orders), the symbionts belong to three Photobacterium species; nonsymbiotic luminous bacteria are Vibrio species. The bacteria are extracellular and tightly packed in tubules that communicate with the exterior, releasing bacteria into the gut of the host or the surrounding sea water. The released bacteria are usually cultivable and can contribute to planktonic populations. Although anomalopids release bacteria and ceratioids have pores that would allow release, the fate of these bacteria is unknown and they cannot be cultured by standard isolation techniques. We report here phylogenetic analysis of 16S ribosomal RNA gene sequences from light organs that show that anomalopid and ceratioid symbionts are not known luminous bacteria, but are new groups related to Vibrio spp. They are characterized by host specificity, deep divergence between symbionts from different genera (anomalopids) or families (ceratioids) and, possibly, parallel divergence of hosts and symbionts.
生物发光共生关系涵盖了从兼性共生到高度适应的、显然是专性的共生关系。发光鲷科（手电筒鱼）包括五个属的热带珊瑚礁鱼类，它们具有大型眶下发光器官。角鮟亚目（深海鮟鱇鱼）包含11个科。其中九个科的雌鱼有一个含有细菌共生体的生物发光诱饵。在所有其他鱼类发光器官共生关系中（发生在5个目10个科中），共生体属于三种发光杆菌属物种；非共生发光细菌是弧菌属物种。这些细菌存在于细胞外，紧密排列在与外部相通的小管中，将细菌释放到宿主肠道或周围海水中。释放出的细菌通常可培养，并能形成浮游菌群。尽管发光鲷会释放细菌，角鮟鱇有允许细菌释放的小孔，但这些细菌的去向未知，且无法通过标准分离技术进行培养。我们在此报告对来自发光器官的16S核糖体RNA基因序列的系统发育分析，结果表明发光鲷和角鮟鱇的共生体不是已知的发光细菌，而是与弧菌属物种相关的新类群。它们的特点是具有宿主特异性，不同属（发光鲷）或科（角鮟鱇）的共生体之间有很大差异，而且宿主和共生体可能存在平行分化。
