Lyubarsky A L, Falsini B, Pennesi M E, Valentini P, Pugh E N
Department of Psychology, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6196, USA.
J Neurosci. 1999 Jan 1;19(1):442-55. doi: 10.1523/JNEUROSCI.19-01-00442.1999.
Molecular biological, histological and flicker electroretinographic results have established that mice have two cone photopigments, one peaking near 350 nm (UV-cone pigment) and a second near 510 nm [midwave (M)-cone pigment]. The goal of this investigation was to measure the action spectra and absolute sensitivities of the UV-cone- and M-cone-driven b-wave responses of C57BL/6 mice. To achieve this goal, we suppressed rod-driven signals with steady or flashed backgrounds and obtained intensity-response relations for cone-driven b-waves elicited by narrowband flashes between 340 and 600 nm. The derived cone action spectra can be described as retinal1 pigments with peaks at 355 and 508 nm. The UV peak had an absolute sensitivity of approximately 8 nV/(photon microm2) at the cornea, approximately fourfold higher than the M peak. In an attempt to isolate UV-cone-driven responses, it was discovered that an orange conditioning flash (lambda > 530 nm) completely suppressed ERG signals driven by both M pigment- and UV pigment-containing cones. Analysis showed that the orange flash could not have produced a detectable response in the UV-cone pathway were their no linkage between M pigment- and UV pigment-generated signals. Because cones containing predominantly the UV and M pigments have been shown to be located largely in separate parts of the mouse retina (), the most probable linkage is coexpression of M pigment in cones primarily expressing UV pigment. New histological evidence supports this interpretation (). Our data are consistent with an upper bound of approximately 3% coexpression of M pigment in the cones that express mostly the UV pigment.
分子生物学、组织学和闪烁视网膜电图结果表明，小鼠有两种视锥光色素，一种在350nm附近达到峰值（紫外视锥色素），另一种在510nm附近（中波（M）视锥色素）。本研究的目的是测量C57BL/6小鼠紫外视锥和M视锥驱动的b波反应的作用光谱和绝对灵敏度。为实现这一目标，我们用稳定或闪烁的背景光抑制视杆驱动信号，并获得了340至600nm窄带闪光诱发的视锥驱动b波的强度-反应关系。推导得到的视锥作用光谱可描述为峰值在355和508nm的视网膜色素。紫外峰值在角膜处的绝对灵敏度约为8nV/（光子·μm²），比M峰值高约四倍。为了分离紫外视锥驱动的反应，我们发现橙色条件闪光（波长>530nm）完全抑制了由含M色素和含紫外色素的视锥驱动的视网膜电图信号。分析表明，如果M色素和紫外色素产生的信号之间没有联系，橙色闪光在紫外视锥通路中不可能产生可检测到的反应。因为主要含有紫外和M色素的视锥细胞已被证明在很大程度上位于小鼠视网膜的不同部位（），最可能的联系是在主要表达紫外色素的视锥细胞中共表达M色素。新的组织学证据支持这一解释（）。我们的数据与在主要表达紫外色素的视锥细胞中M色素共表达上限约为3%一致。
