Photoreceptors convey visual information and come in two flavours; dim-light and bright-light dedicated rod and cones. Both cell types feature highly specialized phototransduction cascades that convert photonic energy into intracellular signals. While a substantial amount of phototransduction gene ohnologs are expressed either in rods or cones, visual guanylyl cyclases (GCs) involved in the calcium (Ca²⁺) dependent feedback regulation of phototransduction are neither rod nor cone specific. The co-existence of visual GCs in both photoreceptor types suggests that specialization of these ohnologs occurred despite their overlapping expression.

中文翻译：

---

在两轮脊椎动物特异性全基因组复制后，视觉和嗅觉鸟苷酸环化酶基因的选择性基因丢失。

光感受器传达视觉信息，有两种口味；暗光和亮光专用杆和锥体。两种细胞类型都具有高度专业化的光转导级联，可将光子能量转化为细胞内信号。虽然大量的光转导基因同源物在视杆细胞或视锥细胞中表达，但参与光转导的钙 (Ca ²⁺ ) 依赖性反馈调节的视觉鸟苷酸环化酶 (GC)既不是视杆细胞也不是视锥细胞特异性。两种光感受器类型中视觉 GC 的共存表明，尽管它们的表达重叠，但这些 ohnologs 还是发生了特化。