Department of Biological Sciences, Florida Institute of Technology, 150 W. University Boulevard, Melbourne, FL, 32901, USA.
Department of Biology, Duke University, 130 Science Dr. Durham, Durham, NC, 27583, USA.
BMC Ecol. 2018 Jan 18;18(1):1. doi: 10.1186/s12898-018-0157-0.
For many fish species, retinal function changes between life history stages as part of an encoded developmental program. Retinal change is also known to exhibit plasticity because retinal form and function can be influenced by light exposure over the course of development. Aside from studies of gene expression, it remains largely unknown whether retinal plasticity can provide functional responses to short-term changes in environmental light quality. The aim of this study was to determine whether the structure and function of the fish retina can change in response to altered light intensity and spectrum-not over the course of a developmental regime, but over shorter time periods relevant to marine habitat disturbance.
The effects of light environment on sensitivity of the retina, as well as on cone photoreceptor distribution were examined in the Atlantic tarpon (Megalops atlanticus) on 2- and 4-month timescales. In a spectral experiment, juvenile M. atlanticus were placed in either 'red' or 'blue' light conditions (with near identical irradiance), and in an intensity experiment, juveniles were placed in either 'bright' or 'dim' light conditions (with near identical spectra). Analysis of the retina by electroretinography and anti-opsin immunofluorescence revealed that relative to fish held in the blue condition, those in the red condition exhibited longer-wavelength peak sensitivity and greater abundance of long-wavelength-sensitive (LWS) cone photoreceptors over time. Following pre-test dark adaption of the retina, fish held in the dim light required less irradiance to produce a standard retinal response than fish held in bright light, developing a greater sensitivity to white light over time.
The results show that structure and function of the M. atlanticus retina can rapidly adjust to changes in environmental light within a given developmental stage, and that such changes are dependent on light quality and the length of exposure. These findings suggest that the fish retina may be resilient to disturbances in environmental light, using retinal plasticity to compensate for changes in light quality over short timescales.
对于许多鱼类物种来说，视网膜功能在生命史阶段之间发生变化，这是编码发育程序的一部分。视网膜变化也表现出可塑性，因为视网膜的形态和功能可以在发育过程中受到光暴露的影响。除了基因表达研究外，人们对视网膜可塑性是否能对环境光质量的短期变化提供功能反应知之甚少。本研究旨在确定鱼类视网膜的结构和功能是否可以响应改变的光强度和光谱而发生变化——不是在发育阶段，而是在与海洋栖息地干扰相关的更短时间内。
在大西洋鲷（Megalops atlanticus）上，在 2 个月和 4 个月的时间尺度上，研究了光环境对视网膜敏感性以及视锥感光器分布的影响。在一项光谱实验中，幼年大西洋鲷被置于“红色”或“蓝色”光条件下（具有几乎相同的辐照度），在强度实验中，幼年大西洋鲷被置于“明亮”或“暗淡”光条件下（具有几乎相同的光谱）。通过视网膜电图和抗视蛋白免疫荧光分析发现，与在蓝色条件下的鱼相比，在红色条件下的鱼表现出更长波长的峰值敏感性和更长波长敏感（LWS）视锥感光器的数量随时间增加。在视网膜的预测试暗适应后，与在明亮光下的鱼相比，在暗淡光下的鱼需要更少的辐照度来产生标准的视网膜反应，随着时间的推移，对白光的敏感性增加。
结果表明，M. atlanticus 视网膜的结构和功能可以在特定发育阶段内快速适应环境光的变化，并且这种变化取决于光质量和暴露时间。这些发现表明，鱼类视网膜可能对环境光的干扰具有弹性，利用视网膜可塑性在短时间内补偿光质量的变化。
