Expression of genes encoding Ca²⁺ exporting proteins in freshwater crayfish Procambarus clarkii during cold exposure

1.This study examined expression of two primary transmembrane Ca²⁺ export proteins (plasma membrane Ca²⁺ ATPase, (PMCA); Na⁺/Ca²⁺ exchanger, sodium/calcium exchanger (NCX)) in epithelial (antennal gland, kidney) and non-epithelial (axial abdominal muscle) tissues of the freshwater crayfish Procambarus clarkii following exposure (28 days) to 4 °C (compared with control 23 °C).2.Crayfish tissues responded to cold exposure within 5-7 days by upregulating the mRNA (determined through real-time polymerase chain reaction (PCR)) for both PMCA and NCX. After 28 days, levels were 4-5× higher in antennal gland and 2-3× higher in muscle. In situ hybridization localized the mRNA increase to the nephridial canal in antennal gland sections and to the extensor muscles in the tail. Western blotting confirmed corresponding increases in PMCA protein expression; however, expression of NCX protein was unchanged.