Post-molt processes of cuticle formation and calcification in the Japanese mitten crab Eriocheir japonicus

Abstract

This study examines the following in the Japanese mitten crab: (1) the structure of the exoskeleton with special reference to its calcification; (2) the progression of post-molt cuticle formation and calcification. In the crab, the structure and calcification state of the exoskeleton at the molt and during the inter-molt stage were similar to those of other crustaceans. During the inter-molt, the exoskeleton consisted of four cuticle layers; the outermost epicuticle, the exocuticle, the endocuticle and the innermost membrane layer. Intense calcification was observed in the exo-and endocuticle. At the molt, the synthesis of the epi-and exocuticle was already complete, and the addition of the endocuticle began after the molt. Calcification of the exocuticle initiated soon after the molt, but there was a delay between endocuticle matrix synthesis and calcification. Histology showed that the process of calcification was similar to that in other crustaceans. However, calcium concentrations within the exoskeleton continued to increase and never reached the levels of the inter-molt stage at the end of the experiment. This suggests that the Japanese mitten crab is relatively slow to calcify compared to other crustaceans.

Effects of dietary cholesterol levels on moulting performance, lipid accumulation, ecdysteroid concentration and immune enzymes activities of juvenile Chinese mitten crabEriocheir sinensis

“…Based on the new cuticle formation and calcification (Sakamoto et al . ) in the lateral spine, the postmoult phase (Freeman et al . ) was subdivided into soft, leathery and paper shell stages.…”

“…Each ecdysis is followed by a postmoult uptake of water, then a rapid growth in body size during the short soft-skinned time (Hartnoll 1982). Based on the new cuticle formation and calcification (Sakamoto et al 2009) in the lateral spine, the postmoult phase (Freeman et al 1987) was subdivided into soft, leathery and paper shell stages. As we known, the moulting of juvenile E. sinensis principally required enough preparations of energy storage (Catacutan 2002), hormone concentration (Chang & Mykles 2011) and immune system protection (Mykles et al 2000).…”

Epidermal carbonic anhydrase activity and exoskeletal metal content during the molting cycle of the blue crab, Callinectes sapidus

“…Adapting the methods of Sakamoto et al (), metal content of the exoskeleton was quantified. Dried carapace samples from each crab were weighed, and then incubated with 50 mL of 5% nitric acid.…”

“…The three main components of crustacean exoskeleton are polysaccharides, proteins, and inorganic compounds (Vigh and Dendinger, ; Pratoomchat et al, ; Sakamoto et al, ). Chitin, the main polysaccharide present in crustacean exoskeleton, forms a matrix with proteins that is mineralized by inorganic compounds, primarily carbonate salts (Pratoomchat et al, , ).…”

The Involvement of Hemocyte Prophenoloxidase in the Shell-Hardening Process of the Blue Crab, Callinectes sapidus

“…The sclerotization occurs in the new soft and pliable cuticle immediately after ecdysis [ 13 – 15 ]. Mineralization, as the second step, incorporates calcium carbonate into the protein matrices of the cuticle in 2.5 hrs after ecdysis [ 8 , 9 , 14 , 16 – 21 ].…”