Past studies have shown that long-term exposure to black substrates led to a significant increase in the abundance of epithelial CRCN protein, and a significant decrease in response to white substrates (Wade et al.,2012). This may indicate that the amount and distribution of this
protein are critical to achieving optimal cooked colour (Wade et al.,2012). The current study used a specific CRCN antibody to discover whether the amount of CRCN protein was controlling short-term adaptive colouration responses. Results showed no relationship between the amount of CRCN protein and the colour of animals exposed to black or white substrates for 2 h (Fig. 3). Although the CRCN protein combines in a 1:1 stoichiometric relationship with free astaxanthin (
Zagalsky, 1985), the CRCN protein is not pigmented unless bound to the carotenoid. Therefore, the total abundance of the CRCN protein would not be measured by purifying and quantifying the pigmented form of the protein alone. Our study indicates that CRCN protein may be present in
prawn epithelial tissue without being bound to free Axn, in a similar way that Axn is found in the epithelial tissue in esterified form without being bound to CRCN. Combined, studies suggest that CRCN protein abundance is not directly related to external prawn colour, and is
unlikely to be the mechanism by which the increase in prawn pigmentation during two-hours exposure to black substrates is regulated. The regulation of carotenoid esterification may be a critical regulator of crustacean colour