Comparative study of collagen distribution in the dermis of the embryonic carapace of soft‐ and hard‐shelled cryptodiran turtles

Abstract

Turtles are characterized by their typical carapace, which is primarily composed of corneous beta proteins in the horny part and collagen in the dermal part. The formation of the extracellular matrix in the dermis of the carapace in a hard‐shelled and a soft‐shelled turtle has been compared. The study examines carapace development, with an emphasis on collagen accumulation, in the soft‐shelled turtle Pelodiscus sinensis and hard‐shelled turtle Trachemys scripta elegans, using comparative morphological and embryological analyses. The histological results showed that collagen deposition in the turtle carapace increased as the embryos developed. However, significant differences were observed between the two turtle species at the developmental stages examined. The microstructure of the dermis of the carapace of P. sinensis showed light and dark banding of collagen bundles, with a higher overall collagen content, whereas the carapacial matrix of T. scripta was characterized by loosely packed and thinner collagenous fiber bundles with a lower percentage of type I collagen. Overall, the formation and distribution of collagen fibrils at specific developmental stages are different between the soft‐and hard‐shelled turtles. These results indicate that the pliable epidermis of the soft‐shelled turtle is supported by a strong dermis that is regularly distributed with collagen and that it allows improved maneuvering, whereas a strong but inflexible epidermis as observed in case of hard‐shelled turtles limits movement.

CRISPR-Cas9-Mediated Mutation of Methyltransferase METTL4 Results in Embryonic Defects in Silkworm Bombyx mori

“…Moreover, these cuticular protein genes had covered almost all the cuticular protein families of RR-1, RR-2, Tweedle, CPFL, CPG, and CPH, with the exception of RR-3 [ 25 ]. Intriguingly, another group of molecular structure such as collagens were all down-regulated in mutation of BmMETTL4 ( Figure 7 C), whereas collagenase responsible for degrading native collagen were significantly up-regulated ( Figure 7 D) [ 26 , 27 ]. These analyses indicated important roles of structural proteins in the process of embryogenesis.…”

“…We also found that there were many DEGs possessing molecular structure activity, including structural molecular proteins in the extracellular matrix (ECM)-interaction pathway such as collagens, that were all generally down-regulated in BmMETTL4 mutant. Collagen can provide structural support for cell growth and proliferation, help maintain the structural integrity of the body and organs, and play a crucial role during embryonic tissue morphogenesis [ 26 ]. In silkworm, we identified 17 collagens belonging to different collagen types in the genome, of which 7 collagens were significantly repressed by depletion of BmMETTL4.…”

Texture quality, histological and extracellular matrix‐related molecular changes of the calipash of Chinese soft‐shelled turtle Pelodiscus sinensis in response to Aeromonas hydrophila challenge

“…The content of hydroxyproline was quantified using acid hydrolysis followed using a colorimetric method according to Reddy and Enwemeka (1996). The detailed procedure was described in Yang et al (2021).…”