Circadian Rhythm Oscillation Affects the Structural Morphology of Eyes in Juvenile Eriocheir sinensis H. Milne-Edwards, 1853 (Decapoda: Varunidae) Exposed to Alternating Dark/Light Conditions

摘要

We examined the effects of light and dark adaptation on the eyes of stage I juveniles of Eriocheir sinensis at both morphological and transcriptome levels. Electron microscopy observations of photoreceptor ultrastructure revealed large amounts of pigment particles and endoplasmic reticulum in the eyes of crabs adapted to a light environment, whereas few of these structures were found in those adapted to a dark environment. On the basis of Illumina sequencing, we obtained high-quality raw reads for light- and dark-adapted crabs. Furthermore, among the obtained genes that were differentially expressed between light and dark adaptation conditions, we found that many genes were significantly up- and/or down-regulated, respectively. We subsequently identified 35 signalling pathways associated with circadian rhythm oscillation. The majority of these signalling pathways are, however, related to cytoskeletal remodelling. These findings at the molecular level correspond to observed changes in the structural features of the eyes of juveniles of E. sinensis in response to the alternate exposure to dark and light conditions during circadian rhythm oscillation.