Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221, USA.
Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221, USA.
Curr Biol. 2024 Apr 8;34(7):1569-1575.e3. doi: 10.1016/j.cub.2024.02.052. Epub 2024 Mar 20.
For eyes to maintain optimal focus, precise coordination is required between lens optics and retina position, a mechanism that in vertebrates is governed by genetics, visual feedback, and possibly intraocular pressure (IOP). While the underlying processes have been intensely studied in vertebrates, they remain elusive in arthropods, though visual feedback may be unimportant. How do arthropod eyes remain functional while undergoing substantial growth? Here, we test whether a common physiological process, osmoregulation, could regulate growth in the sophisticated camera-type eyes of the predatory larvae of Thermonectus marmoratus diving beetles. Upon molting, their eye tubes elongate in less than an hour, and osmotic pressure measurements reveal that this growth is preceded by a transient increase in hemolymph osmotic pressure. Histological evaluation of support cells that determine the lens-to-retina spacing reveals swelling rather than the addition of new cells. In addition, as expected, treating larvae with hyperosmotic media post-molt leads to far-sighted (hyperopic) eyes due to a failure of proper lengthening of the eye tube and results in impaired hunting success. This study suggests that osmoregulation could be of ubiquitous importance for properly focused eyes.
为了使眼睛保持最佳的聚焦状态，晶状体光学和视网膜位置之间需要精确的协调，这一机制在脊椎动物中受遗传、视觉反馈和眼内压（IOP）的控制。虽然脊椎动物中的这些基本过程已经被深入研究，但在节肢动物中仍然难以捉摸，尽管视觉反馈可能不重要。节肢动物的眼睛在经历大量生长的同时如何保持功能？在这里，我们测试了一个常见的生理过程，即渗透调节，是否可以调节捕食性幼虫 Thermonectus marmoratus 潜水甲虫的复杂相机型眼睛的生长。蜕皮后，它们的眼管在不到一个小时的时间内延长，渗透压测量显示，这种生长之前会短暂增加血淋巴渗透压。确定晶状体到视网膜间距的支持细胞的组织学评估显示，细胞肿胀而不是添加新细胞。此外，正如预期的那样，幼虫在蜕皮后用高渗介质处理会导致远视（远视）眼，因为眼管没有适当延长，导致狩猎成功率下降。这项研究表明，渗透调节对于保持适当聚焦的眼睛可能具有普遍重要性。
