Calreticulin (CRT), a well conserved endoplasmic reticulum‐resident protein for Ca2+‐binding, is widely expressed in multicellular eukaryotes. CRT plays a key role in many cellular processes, including Ca2+ homeostasis. To address the role of CRT underlying the Ca2+ homeostasis alternation during the mineralization cycle of the mud crab (Scylla paramamosain), we cloned the full‐length cDNA of CRT gene (SpCRT) from S. paramamosain, and its protein contains all signature domains of CRT. Tissue distribution showed the SpCRT transcript was far more abundant in hepatopancreas than in others. Meanwhile, seven moult stages of the crab were characterized by observing the third maxilliped under microscope and clear uropod images were presented. During the moult cycle, the total calcium levels in the hepatopancreas were determined using ICP‐AES. It decreased significantly at stage A and B (p < 0.05), and was relatively steady between inter‐moult C and early pre‐moult D0 (p > 0.05). It was then gradually increased thereafter by nearly 274.2% until stage E (compared with stage C) (p < 0.05). Additionally, the expression of SpCRT in the hepatopancreas was the lowest in the moult stage E and post‐moult stage A, and then it maintained at a high level in other stages. Taken together, the relative retard timing of calcium incrument corresponding to the higher expression of SpCRT may suggest CRT plays a critical role in Ca2+ storage in hepatopancreas during the moult cycle of crustaceans.
Two full-length cDNA sequences of 14-3-3 genes were isolated from the mud crab, Scylla paramamosain Estampador, 1949, using RT-PCR and RACE (rapid-amplification of cDNA ends). Sequence analysis indicates that both 14-3-3 genes contain an open reading frame of 744 bp with a deduced 247-amino-acid protein. The gene and protein sequences of Sp14-3-3 genes show 96 and 97% identity, respectively, and both Sp14-3-3 cluster together with other animal 14-3-3 proteins in phylogenetic tree analysis. Tissue specific expression analysis reveals that both Sp14-3-3 genes are ubiquitously expressed, however, their expression patterns are different from each other. Expressions of both Sp14-3-3 genes are sensitive to salinity decrease, even a 5 ppt drop from 30 ppt to 25 ppt, indicating that Sp14-3-3 genes are involved in osmoregulation. Our observations may contribute to a better understanding of the molecular and functional evolution of the 14-3-3 family in both crustaceans and (in)vertebrates as a whole.
Juvenile hormones (JHs) constitute a family of sesquiterpenoids with versatile roles in the regulation of moult, development, metamorphosis, reproductive maturation and polyphenisms in arthropods (Riddiford et al., 2010;Truman & Riddiford, 2007).JHs are well known to prevent early metamorphosis. In particular, the presence of JH during pre-ultimate juvenile stages determines that the next stage will be a juvenile, and disappearance of JH triggers metamorphosis (Jindra et al., 2013). Therefore, the accurate regulation of juvenile hormone titres is crucial for insect moulting and metamorphosis. Several forms of JH have been identified in insects, with JH III being the most common (Bergot et al., 1981).
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