Does the egg capsule protect against chronic UV-B radiation? A study based on encapsulated and decapsulated embryos of cuttlefish Sepia officinalis

Although the egg capsule plays a crucial role in the embryonic development
of cephalopods, its ability to protect embryos from Ultraviolet (UV)
radiation is unknown. Our study evaluated the photoprotection mechanisms
of Sepia officinalis to UV-B radiation and estimated the ability of the
black capsule to act as a physical shield against it. Embryos with (BC)
and without capsule (WC) and juveniles were exposed to four experimental
UVB conditions for 55 days. The effects of different UVB doses were
evaluated in terms of morphological abnormalities and differences in gene
expression between each group. We observed that the development might be
severely impaired in embryos exposed to UVB without capsule protection and
these effects were time- and UVB-dose-dependent. In addition, we found
variations in gene expression levels (light-sensitive, stress response,
and DNA repair) in different tissues as a function of UVB doses. We
suggest a relationship between morphological abnormalities and the limit
of molecular regulation. These results suggest that the quantitative
differences in expression are essential for defining the survivability of
the embryo face to UVB. Thus, we demonstrated that the egg capsule could
ensure successful embryonic development of the cuttlefish S. officinalis
even at high doses of UVB.