大菱鲆幼鱼视网膜结构及不同光谱下视蛋白基因表达特征的研究

大菱鲆(Scophthalmus maximus)是中国重要的养殖鱼类之一, 其生活史经历不同的栖息地和光环境, 视觉器官结构及视觉功能也具有适应性发育特征和可塑性。本研究以不同发育阶段的大菱鲆幼鱼为对象, 探究了其视网膜结构变化、视蛋白基因的表达特征及其与光谱之间的关系。结果表明, 随着大菱鲆幼鱼的生长发育, 其视网膜的外核层逐渐变厚; 视锥视杆层的厚度变化不明显; 而内核层与神经节细胞层逐渐变薄。视紫红质基因rh1与视蛋白基因总表达量的比例上升, 由2月龄的57.35%上升到9月龄77.19%; 视锥蛋白基因与视蛋白基因总表达量的比例下降; 其中红视蛋白基因lws 由2月龄的4.49%下降至9月龄的0.13%。将7月龄的大菱鲆幼鱼用不同光谱处理75 d后, 其视蛋白基因的表达会随光谱环境的变化而发生改变。与全光谱相比, rh2b1、sws2、sws1在红、黄光下的表达量显著下降, 而rh2b1在蓝、绿光下表达显著上升、sws2在绿光下表达显著上升, 其他则变化不显著(P<0.05)。黄、绿、蓝及全光谱下rh2基因家族与视蛋白基因总表达量的比例最高, 而红光下基因rh1的表达量占比最高。大菱鲆幼鱼在不同阶段以及不同光谱处理下表现出了视蛋白基因表达的可塑性以适应不同水层的光谱环境。本研究为探究大菱鲆对光环境的适应机制及工厂化养殖光照调控技术的建立提供理论参考。

Development of retinal structures and opsin gene expression under different spectra in juvenile turbot

Turbot (Scophthalmus maximus) is an economically important cultured fish. Its retinal structure and light-sensing ability vary during its lifespan as it adapts to the change in its niche from the planktonic to the benthic region. In this study, we studied juvenile turbot at different developmental stages and assessed the development of retinal structures and expression of opsin genes in response to different light spectra. We observed that the outer thickness of the retinal nucleus increased as the turbot grew, whereas the thickness of rods and cones remained constant. Additionally, the inner nuclear layer and layer of ganglion cells shrank. The expression ratio of rh1 to total opsin genes increased gradually from 57.35% in two-month-old turbot to 77.19% in nine-month-old turbot. The ratio of the expression of cone opsin genes to total opsin genes decreased, particularly for lws, whose expression proportion changed from 4.49% at two months to 0.13% at nine months. Moreover, strong correlations were detected between opsin expression patterns in response to different light spectra. The expression of rh2b1, sws2, and sws1 decreased significantly in seven-month-old turbot under red and yellow light (P<0.05), whereas the expression of rh2b1 increased under blue and green light. The expression of sws2 increased only under the green light. The rh2 family of opsins dominated the expression among opsins under yellow, green, and blue light and under full spectrum light. The only dominant opsin gene after treatment with red light was rh1. Our results revealed a change in turbot opsins upon varying the light spectra, probably in coordination with its life span at different depths. Therefore, our study may provide essential genomic resources for future industrial applications in the turbot industry.