Gehring Walter J
Biozentrum, University of Basel, Switzerland.
Int J Dev Biol. 2002 Jan;46(1):65-73.
Mutations in the Pax 6 homologs of mammals and insects prevent eye development and targeted expression of both mammal and insect Pax 6 homologs is capable of inducing functional ectopic eyes. Supported by RNA interference experiments in planarians and nemerteans, these findings indicate that Pax 6 is a universal master control gene for eye morphogenesis. Since all metazoan eyes use rhodopsin as a photoreceptor molecule and the same master control gene for eye development, we postulate a monophyletic origin of the various eye types. The finding of well developed eyes in jellyfish which essentially lack a brain, leads us to propose that the eye as a sensory organ evolved before the brain which is an information processing organ. The finding of highly developed eyes with a lens, vitreous body, stacked membranes like a retina and shielding pigment in unicellular dinoflagellates, raises the possibility that the prototypic eyes might have been acquired from symbionts.
哺乳动物和昆虫的Pax 6同源基因发生突变会阻止眼睛发育，而哺乳动物和昆虫的Pax 6同源基因的靶向表达能够诱导功能性异位眼的形成。这些发现得到了涡虫和纽形动物中RNA干扰实验的支持，表明Pax 6是眼睛形态发生的通用主控基因。由于所有后生动物的眼睛都使用视紫红质作为光感受器分子，并且眼睛发育使用相同的主控基因，我们推测各种眼睛类型具有单系起源。在基本上没有大脑的水母中发现发育良好的眼睛，这使我们提出，眼睛作为一种感觉器官比作为信息处理器官的大脑进化得更早。在单细胞双鞭毛虫中发现了具有晶状体、玻璃体、类似视网膜的堆叠膜和屏蔽色素的高度发达的眼睛，这增加了原型眼睛可能是从共生体获得的可能性。
